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Sample records for modeling steam sterilization

  1. 7 CFR 305.23 - Steam sterilization treatment schedules.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 5 2010-01-01 2010-01-01 false Steam sterilization treatment schedules. 305.23... Steam sterilization treatment schedules. Treatment schedule Temperature( °F) Pressure Exposure period (minutes) Directions T303-b-1 10 lbs 20 Use 28″ vacuum. Steam sterilization is not practical for treatment...

  2. Radiosterilization or sterilization by steam. Procedures for sterilization of spices

    International Nuclear Information System (INIS)

    Warmbold, J.

    1994-01-01

    The article compares two different methods for the sterilization of spices, namely radiosterilization and sterilization with steam. The first method applies ionizing radiation which can alter the chemical composition of the products. Tests have shown, however, that radiation doses up to 10 kGy will not induce the formation of carcinogenic agents in the foodstuffs, or of toxic substances, and thus are a wholesome method of preservation. Any modifications of taste, color or smell, or loss of vitamins, can be avoided by proper dose control and standard irradiation conditions. Sterilization by steam is a method achieving substantial suppression of the formation of germs, aerobic spores, yeasts, mould, and gramnegative germs, while preserving in most cases the essential oils. It may result in sensoric alterations, i.e affect the color, smell or taste, but in general the spices thus treated preserved their characteristic properties. The method is a good alternative to radiosterilization. The article adds some concluding information on mandatory labelling of irradiated food imported from third countries

  3. Steam sterilization of air turbine dental handpieces.

    Science.gov (United States)

    Edwardsson, S; Svensäter, G; Birkhed, D

    1983-12-01

    The efficacy of autoclaving high-speed dental handpieces was tested in two types of downward displacement steam sterilizers (instrument autoclaves), commonly used in the dentist's office. Eight series of experiments were performed with various sterilization schedules. Lubrication oils with or without antimicrobial agent were used in four of the series. Each handpiece was inoculated with 1 ml of a suspension containing equal amounts of saliva and spores of Bacillus stearothermophilus (approx. 10(6) spores/ml). Neither sterilization at 120-124 degrees C for 20 min nor at 134-136 degrees C for 10 min resulted in complete inactivation of the spores in series in which the instruments were tested without oil or with oil containing no antimicrobial agent. However, when the handpieces were lubricated with oil containing isopropanol and formaldehyde and the schedule 134-136 degrees C/10 min was used, no growth was observed. The results indicate that instrument autoclaves with built-in programs of 120-124 degrees C/20 min and 134-136 degrees C/10 min could have insufficient capacity to sterilize lubricated or unlubricated dental handpieces. The use of oils containing an antimicrobial agent can overcome this problem.

  4. Monitoring of steam sterilization processes in the dental office

    NARCIS (Netherlands)

    van Doornmalen, J.P.C.M.; Rietmeijer, A.G.M.; Feilzer, A.J.; Kopinga, K.

    2013-01-01

    In dental offices steam sterilization is used to prevent infection of staff and patient. The necessity of sterilization is obvious. To ensure effective sterilization processes each load has to be monitored. Based on literature and standards a state of the art concept of every load monitoring is

  5. Microbiological evaluation of the steam sterilization of assembled laparoscopic instruments

    Directory of Open Access Journals (Sweden)

    Tamara Carolina de Camargo

    Full Text Available ABSTRACT Objective: assess the safety of steam sterilization of assembled laparoscopic instruments with challenge contamination. Method: a laboratory experimental study, using as test samples trocars and laparoscopic graspers. Geobacillus stearothermophillus ATCC-7953 was used, with a microbial population of 106UFC/Filter paper substrate, removed from the biological indicator. Three of them were introduced into each instrument at the time of assembly, and sterilized at pressurized saturated steam, 134oC for 5 minutes. After sterilization, the instrument was disassembled and each filter paper substrate was inoculated in soybean casein culture and incubated at 56oC for 21 days. In case of absence of growth, they were subjected to heat shock of 80oC, for 20 minutes and re-incubated for 72 hours. Sample size: 185 graspers and 185 trocars, with 95% power. We paired the experiments with comparative negative control groups (5 graspers and 5 trocars with challenge contamination, sterilized disassembled and positive control (30 filter paper supports, unsterilized, subject to the same incubation procedures. Results: there was no microbial growth in experimental and negative control. The results of the positive control were satisfactory. Conclusion: this study provided strong scientific evidence to support the safety of steam sterilizing of the assembled laparoscopic instrument.

  6. Sterility Maintenance Assessment of Moist/Wet Material After Steam Sterilization and 30-day Storage

    OpenAIRE

    Moriya,Giovana Abrahão de Araújo; Graziano,Kazuko Uchikawa

    2010-01-01

    Moist/wet materials stored after autoclaving are considered contaminated and not recommended for use. This study evaluates the maintenance of sterility in moist/wet material after being submitted to steam sterilization and stored for a period of 30 days. Aiming to support decision-making in emergency situations, 40 surgical boxes packed in nonwoven cloth covering Spunbound, Metblouwn, Spunbound (SMS): half (the experimental group) were placed in an autoclave but the drying phase was interrupt...

  7. Release of bacteria during the purge cycles of steam-jacketed sterilizers.

    Science.gov (United States)

    Marshall, B M; Shin-Kim, H; Perlov, D; Levy, S B

    1999-01-01

    The design of the steam-jacketed sterilizer includes an exterior air-gap fixture through which purged chamber aerosols potentially could escape into the ambient environment. Studies of the purge cycle in two sterilizer models tested the potential release of a genetically marked Enterococcus faecalis, together with Bacillus stearothermophilus spores introduced as exposed cultures. Direct plate counts, broth enrichment and polymerase chain reaction analysis were used to confirm any released organisms trapped in an all-glass impinger. From the retrieval of both bacterial strains, an estimated 10(3) organisms can be released from uncontained bacterial loads of 10(11) E. faecalis and 10(7) B. stearothermophilus, even from properly functioning autoclaves. The release of an opportunistic pathogen from sterilizer purge exhausts emphasises the importance of proper sterilizer location, ventilation, containment of heavily contaminated loads, and adequate sterilizer maintenance.

  8. Sterility maintenance assessment of moist/wet material after steam sterilization and 30-day storage.

    Science.gov (United States)

    Moriya, Giovana Abrahão de Araújo; Graziano, Kazuko Uchikawa

    2010-01-01

    Moist/wet materials stored after autoclaving are considered contaminated and not recommended for use. This study evaluates the maintenance of sterility in moist/wet material after being submitted to steam sterilization and stored for a period of 30 days. Aiming to support decision-making in emergency situations, 40 surgical boxes packed in nonwoven cloth covering Spunbound, Metblouwn, Spunbound (SMS): half (the experimental group) were placed in an autoclave but the drying phase was interrupted, yielding moist/wet materials and the other half (the negative control group) underwent the complete cycle. The external parts of each surgical box were deliberately contaminated with Serratia marcescens and subsequently stored for 30 days. After this period, the boxes' contents were submitted to sterility tests and no growth was observed. The presence of moisture inside the surgical boxes did not interfere with maintaining their sterility.

  9. Criteria for determining steam sterilization cycles for lubricated and nonlubricated mechanical equipment.

    Science.gov (United States)

    Halleck, F E; Mizuba, S; Zimmer, D I; Woodrow, J

    1979-01-01

    Requirements and procedures for determining steam sterilization cycles for lubricated and nonlubricated, complex, mechanical equipment are established. Factors affecting exposure times are discussed, as are procedures and data needed to determine the penetrability of steam into mechanical equipment, and the effect of lubricating oil in impeding steam penetration to the spore. The total effects of these factors in sterilizing times are presented. Sterilizers with a prevacuum cycle, which can remove air from the equipment efficiently and replace it with saturated steam, are recommended for complex mechanical equipment.

  10. Following trends in steam sterilizer performance by quantitative monitoring of non-condensable gases.

    Science.gov (United States)

    van Wezel, R A C; van Gastel, A; de Ranitz, A; van Doornmalen Gomez Hoyos, J P C M

    2017-12-01

    Standards require a daily steam penetration test before starting production with a steam sterilizer. In many cases the results of steam penetration tests are not used for improvements or optimization of processes. This study aimed to detect whether trend analysis with an objective and quantifying steam penetration test has added value for the end-user. The databases of an objective quantifying steam penetration test, from the hospital and the manufacturer, are coupled and analysed. In this study, the databases included five steam sterilizers and approximately a four-year period. Based on the analysis, the process of the sterilizers was optimized. The results of the steam penetration tests became more stable over longer periods. This may result in lengthened periods between maintenance and validation. The analysis demonstrates that an objective, quantifying steam penetration test delivers more insights and knowledge of the functioning of the steam sterilization process. This knowledge may be used to optimize the process and reduce costs for the end-user. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  11. Radiosterilization and steam autoclaving sterilization effects on phosphite antioxidant stability

    Science.gov (United States)

    Yagoubi, N.; Boucherie, P.; Ferrier, D.

    1997-08-01

    While the radiosterilization by γ rays, is mainly employed for medical devices, this procedure is not commonly used to sterilize and decontaminate raw material and finished product used in the pharmaceutical industry. Depending on the countries, the requirements for obtaining approval to treat this class of product with γ rays may be different. Usually it is the responsibility of the manufacturer to demonstrate not only the integrity of the irradiated product, but olso its efficiency, safety and quality. Our work consists of a comparative study of the effects of γ radiotreatment at 25 kGy and steam sterilisation on phosphite antioxidant incorporated in polypropylene. The γ radiosensitivity compared with thermolability of this antioxidant was studied by reversed phase HPLC, Fourier Transform Infrared (IRFT) and Differential Scanning Calorimetry (DSC). The results obtained proved that the phosphite incorporated into the polymer and treated with the two types of sterilisation is rapidly oxidized in phosphate. Nevertheless, this oxidation is more important when using radiotreatment at 25 kGy.

  12. Microbiological evaluation of the steam sterilization of assembled laparoscopic instruments.

    Science.gov (United States)

    Camargo, Tamara Carolina de; Graziano, Kazuko Uchikawa; Almeida, Alda Graciele Claudio Dos Santos; Suzuki, Karina; Silva, Cely Barreto da; Pinto, Flávia Morais Gomes

    2016-11-21

    assess the safety of steam sterilization of assembled laparoscopic instruments with challenge contamination. a laboratory experimental study, using as test samples trocars and laparoscopic graspers. Geobacillus stearothermophillus ATCC-7953 was used, with a microbial population of 106UFC/Filter paper substrate, removed from the biological indicator. Three of them were introduced into each instrument at the time of assembly, and sterilized at pressurized saturated steam, 134oC for 5 minutes. After sterilization, the instrument was disassembled and each filter paper substrate was inoculated in soybean casein culture and incubated at 56oC for 21 days. In case of absence of growth, they were subjected to heat shock of 80oC, for 20 minutes and re-incubated for 72 hours. Sample size: 185 graspers and 185 trocars, with 95% power. We paired the experiments with comparative negative control groups (5 graspers and 5 trocars with challenge contamination, sterilized disassembled) and positive control (30 filter paper supports, unsterilized), subject to the same incubation procedures. there was no microbial growth in experimental and negative control. The results of the positive control were satisfactory. this study provided strong scientific evidence to support the safety of steam sterilizing of the assembled laparoscopic instrument. avaliar a segurança da esterilização a vapor, do instrumental laparoscópico montado com desafio da contaminação. estudo experimental laboratorial, cujo corpo de prova foram trocarte e pinça laparoscópica. Utilizou-se esporos Geobacillus stearothermophillus ATCC-7953, com população microbiana de 106UFC/suporte de papel filtro, removidos do indicador biológico. Três deles foram introduzidos no interior de cada instrumento, no momento da montagem, sendo esterilizados a vapor saturado sob pressão, 134oC por 5 minutos. Depois da esterilização, o instrumental foi desmontado, e cada suporte de papel filtro foi inoculado em meio de cultura

  13. Evaluation of steam sterilization conditions for [{sup 18}F]fludeoxyglucose

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Priscilla F.; Nascimento, Leonardo T.; Valente, Eduardo S.; Silva, Juliana B.; Silveira, Marina B.; Ferreira, Soraya Z., E-mail: somafe@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Unidade de Pesquisa e Producao de Radiofarmacos

    2011-07-01

    [{sup 18}F]Flu deoxyglucose ({sup 18}FDG) is the most commonly used radiopharmaceutical for positron emission tomography. Sterile filtration of the final product into sterile vials using 0.22 {mu}m filter membrane is usually adopted for {sup 18}FDG. However, Good Manufacturing Practice (GMP) guidelines recommend heat sterilization as the method of choice to ensure sterility of pharmaceutical preparations. The aim of this study was to essay different steam sterilization conditions in order to choose the best one for {sup 18}FDG. Three different sterilization conditions were essayed. The first one at 121 deg C for 15 minutes, the second one at 135 deg C for 3.5 minutes and the third one at 133 deg C for 2 minutes. {sup 18}FDG pH-formulation was kept around 6.0. At the end of autoclave cycles, {sup 18}FDG sterility was evaluated by direct inoculation of {sup 18}FDG in culture media and radiochemical purity was determined by TLC and HPLC. Results demonstrated that all essayed conditions were able to ensure {sup 18}FDG sterility, but caused a decrease in radiochemical purity of {sup 18}FDG. Autoclave cycle at 133 deg C for 2 minutes was the best essayed condition for {sup 18}FDG terminal sterilization, once it provided the greater radiochemical purity value and took less time. {sup 18}FDG was able to meet specifications after autoclave cycles, what supports the application of steam sterilization in routine {sup 18}FDG production, in compliance with GMP. (author)

  14. Steam sterilization costs: a guide for the central service manager.

    Science.gov (United States)

    O'Shaughnessy, K L

    1993-07-01

    The Nassau County Medical Center CS department, East Meadow, New York, was faced with a staff layoff and an increased workload. With some hard thinking and strong staff support, new processes/systems were designed to save time and money. These included outsourcing the sterilization of "easy" trays, instituting a case cart program and developing custom packs. In order to determine where savings could be had, it was first important to examine current costs. By breaking the costs of sterilization processing down into an average cost per load, a formula was developed that helped determine many additional cost comparisons for the department. For example, the cost analysis formula could be used by CS departments to determine the cost-effectiveness of off-site sterilization, to compare using disposable vs. reusable items and to determine costs for EtO sterilization and aeration.

  15. Full-cycle steam sterilization in ophthalmic surgery-the effect of wrapping instruments.

    Science.gov (United States)

    Carpel, Emmett F; Mancera, Alejandra Decanini; Rowan, Larée L; Entine, Gerald; Entine, Oliver

    2012-03-01

    To determine if wrapping instruments in conjunction with full-cycle steam sterilization affects the incidence of postoperative infection in patients undergoing ophthalmic surgery in a dedicated eye center. Retrospective, consecutive-case, comparative study. Two consecutive groups, each of approximately 19 000 ophthalmic surgical patients, were reviewed for postoperative infection. For both groups, the surgical instruments were sterilized using full-cycle, steam sterilization, with a single major difference. The instruments for the first group were sterilized with equipment located adjacent to the operating room and no wrapping of the instruments was used, whereas for the second group, the sterilization equipment was located at a central facility and the instruments were wrapped before being transported to the operating rooms. In the unwrapped sterilization group 17 presumed postoperative infections were identified, compared to 9 presumed infections in the wrapped sterilization group. Because the observed infection rates for each group were so low, this apparent difference is not statistically significant (P = .16). Similarly, differences found in the incidence of culture-positive cases of endophthalmitis (5 for unwrapped vs 3 for wrapped) were not statistically significant (P = .47). In a dedicated, high-volume eye facility, the incidence of presumed postoperative infection associated with unwrapped and wrapped full-cycle steam sterilization were shown to be identical within statistical error. This provides strong evidence that if eye surgical facilities carefully clean surgical instruments and follow the industry and manufacturer guidelines, they can, with confidence, use either of these 2 methods of sterilization. This study presents the first concrete data that corroborate the current position of The Joint Commission, American Academy of Ophthalmology (AAO) and American Society of Cataract and Refractive Surgery (ASCRS). Copyright © 2012 Elsevier Inc. All

  16. Steam sterilization and automatic dispensing of [{sup 18}F]fludeoxyglucose (FDG) for injection

    Energy Technology Data Exchange (ETDEWEB)

    Karwath, Pascal [Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany) and MC-Pharma GmbH (MCP), Bonn (Germany)]. E-mail: p.karwath@uni-bonn.de; Sartor, Johannes [MC-Pharma GmbH (MCP), Bonn (Germany); Gries, Wolfgang [MC-Pharma GmbH (MCP), Bonn (Germany); Wodarski, Christine [MC-Pharma GmbH (MCP), Bonn (Germany); Dittmar, Claus [MC-Pharma GmbH (MCP), Bonn (Germany); Biersack, Hans J. [Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany); Guhlke, Stefan [Department of Nuclear Medicine, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn (Germany) and MC-Pharma GmbH (MCP), Bonn (Germany)]. E-mail: stefan.guhlke@ukb.uni-bonn.de

    2005-04-01

    For the purpose of implementing steam sterilization of 2-[{sup 18}F]FDG (FDG) in the final container into routine production, we have validated and established a fully automated dispensing and sterilization system, thereby considerably reducing the radiation burden to the personnel. Methods: The commercially available system combines aseptic dispensing of the product solution under a miniaturized laminar flow unit with subsequent steam sterilization, realized by heating of the product in the final containers by an autoclave included in the dispensing unit, thus incorporating current pharmaceutical manufacturing standards for the production of parental radiopharmaceuticals. The efficiency of the used sterilization cycle, the stability of FDG under the conditions of sterilization and the stability of the final product towards radiolysis was investigated with respect to various pH-formulations. Results: The system was found to be fully valid for filling of vials in a laminar flow class A (US-class 100) environment and for sterilization of FDG in the final container. The pH for sterilizing FDG solutions must be slightly acidic to avoid decomposition. A pH of 5.5 appears to be optimal and gives FDG of very high radiochemical purity ({approx}99%). In addition, radiolysis of FDG in solutions of high activity concentration was significantly lower at pH 5.5 than at neutral pH. Conclusion: Terminal sterilization enables the production of FDG in full compliance with GMP-regulations even in Class C or D (US class 10,000 or 100,000) laboratories.

  17. Steam sterilization and automatic dispensing of [18F]fludeoxyglucose (FDG) for injection

    International Nuclear Information System (INIS)

    Karwath, Pascal; Sartor, Johannes; Gries, Wolfgang; Wodarski, Christine; Dittmar, Claus; Biersack, Hans J.; Guhlke, Stefan

    2005-01-01

    For the purpose of implementing steam sterilization of 2-[ 18 F]FDG (FDG) in the final container into routine production, we have validated and established a fully automated dispensing and sterilization system, thereby considerably reducing the radiation burden to the personnel. Methods: The commercially available system combines aseptic dispensing of the product solution under a miniaturized laminar flow unit with subsequent steam sterilization, realized by heating of the product in the final containers by an autoclave included in the dispensing unit, thus incorporating current pharmaceutical manufacturing standards for the production of parental radiopharmaceuticals. The efficiency of the used sterilization cycle, the stability of FDG under the conditions of sterilization and the stability of the final product towards radiolysis was investigated with respect to various pH-formulations. Results: The system was found to be fully valid for filling of vials in a laminar flow class A (US-class 100) environment and for sterilization of FDG in the final container. The pH for sterilizing FDG solutions must be slightly acidic to avoid decomposition. A pH of 5.5 appears to be optimal and gives FDG of very high radiochemical purity (∼99%). In addition, radiolysis of FDG in solutions of high activity concentration was significantly lower at pH 5.5 than at neutral pH. Conclusion: Terminal sterilization enables the production of FDG in full compliance with GMP-regulations even in Class C or D (US class 10,000 or 100,000) laboratories

  18. Reason behind wet pack after steam sterilization and its consequences: An overview from Central Sterile Supply Department of a cancer center in eastern India.

    Science.gov (United States)

    Basu, Debabrata

    Wet pack after steam sterilization process that means there are surely obtain millions of microorganisms that can breed and multiply rapidly and objects are unsterile and can never be used for further procedure. There are many reasons behind the wet pack occurrences after autoclaving like poor quality of wrapping materials, faulty valves of rigid container, faulty loading and packaging technique, poor steam quality, sterilizer malfunction and may be design related problems in CSSD sterile storage area. Cause of wet pack after steam sterilization processes may occur severe problems because of wasted time and effort, increased work load, increased cost, potentially contaminated instruments, infection risk to the patient, poor patient outcomes and delayed or cancellation of procedures. But such wet pack scenario can be avoided by various methods by using good steam (water) quality, performing periodic maintenance of the Autoclaves, avoidance of sterilizer overloading, allowing adequate post sterilization time to cool down the materials to room temperature, using good quality wrapping materials, properly maintain temperature and humidity of sterile storage area etc. Copyright © 2016 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

  19. Model of reverse steam generator

    International Nuclear Information System (INIS)

    Malasek, V.; Manek, O.; Masek, V.; Riman, J.

    1987-01-01

    The claim of Czechoslovak discovery no. 239272 is a model designed for the verification of the properties of a reverse steam generator during the penetration of water, steam-water mixture or steam into liquid metal flowing inside the heat exchange tubes. The design may primarily be used for steam generators with a built-in inter-tube structure. The model is provided with several injection devices configured in different heat exchange tubes, spaced at different distances along the model axis. The design consists in that between the pressure and the circumferential casings there are transverse partitions and that in one chamber consisting of the circumferential casings, pressure casing and two adjoining partitions there is only one passage of the injection device through the inter-tube space. (Z.M.). 1 fig

  20. Probabilistic model for sterilization of food

    International Nuclear Information System (INIS)

    Chepurko, V.V.; Malinovskij, O.V.

    1986-01-01

    The probabilistic model for radiation sterilization is proposed based on the followng suppositions: (1) initial contamination of a volume unit of the sterilized product m is described by the distribution of the probabilities q(m), (2) inactivation of the population from m of microorganisms is approximated by Bernoulli test scheme, and (3) contamination of unit of the sterilized product is independent. The possibility of approximation q(m) by Poisson distribution is demonstrated. The diagrams are presented permitting to evaluate the dose which provides the defined reliability of sterilization of food for chicken-gnotobionts

  1. Parametric study for horizontal steam generator modelling

    Energy Technology Data Exchange (ETDEWEB)

    Ovtcharova, I. [Energoproekt, Sofia (Bulgaria)

    1995-12-31

    In the presentation some of the calculated results of horizontal steam generator PGV - 440 modelling with RELAP5/Mod3 are described. Two nodalization schemes have been used with different components in the steam dome. A study of parameters variation on the steam generator work and calculated results is made in cases with separator and branch.

  2. Effects of sterilization with hydrogen peroxide gas plasma, ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints.

    Science.gov (United States)

    Gatineau, Matthieu; El-Warrak, Alexander O; Bolliger, Christian; Mourez, Michael; Berthiaume, Frederic

    2012-10-01

    To compare effects of sterilization with hydrogen peroxide gas plasma (HPGP), ethylene oxide, and steam on bioadhesive properties of nylon and polyethylene lines used for stabilization of canine stifle joints. Samples of a 36.3-kg test nylon leader line, 57.8-kg test nylon fishing line, and 2-mm ultrahigh-molecular weight polyethylene (UHMWPE) were used. In this in vitro study, samples of nylon leader line, fishing line, and UHMWPE sterilized by use of HPGP, ethylene oxide, and steam or unsterilized samples were used. Bacterial adherence on unsterilized and sterilized samples was tested with Staphylococcus epidermidis and Escherichia coli. Five samples were examined for each line type and sterilization condition, and final colony counts were obtained. Bacterial adherence was significantly affected by method of sterilization for all 3 line types. For most of the samples, bacterial adherence was similar or lower when HPGP sterilization was used, compared with results for sterilization via ethylene oxide and steam, respectively. Bacterial adherence was significantly higher for UHMWPE, compared with adherence for the nylon line, regardless of the sterilization method used. Bacterial adherence was higher for nylon fishing line than for nylon leader line for S epidermidis after ethylene oxide sterilization and for E coli after HPGP and ethylene oxide sterilization. Effects of HPGP sterilization on bioadhesive properties of nylon and polyethylene lines compared favorably with those for ethylene oxide and steam sterilization. Also, nylon line may be a more suitable material than UHMWPE for suture prostheses on the basis of bacterial adherence properties.

  3. The effect of steam sterilization on the accuracy of spring-style mechanical torque devices for dental implants

    Directory of Open Access Journals (Sweden)

    Mahshid M

    2012-07-01

    Full Text Available Minoo Mahshid,1 Aboulfazl Saboury,1 Ali Fayaz,1 Seyed Jalil Sadr,1 Friedrich Lampert,2 Maziar Mir2,31Department of Prosthodontics, Dental School, Shahid Beheshti University of Medical Sciences, Tehran, Iran; 2Department of Conservative Dentistry, Aachen RWTH Hospital, Aachen, Germany; 3Beckman Laser Institute, UCI, Irvine, CA, USABackground: Mechanical torque devices (MTDs are one of the most commonly recommended devices used to deliver optimal torque to the screw of dental implants. Recently, high variability has been reported about the accuracy of spring-style mechanical torque devices (S-S MTDs. Joint stability and survival rate of fixed implant supported prosthesis depends on the accuracy of these devices. Currently, there is limited information on the steam sterilization influence on the accuracy of MTDs. The purpose of this study was to assess the effect of steam sterilization on the accuracy (±10% of the target torque of spring-style mechanical torque devices for dental implants.Materials and methods: Fifteen new S-S MTDs and their appropriate drivers from three different manufacturers (Nobel Biocare, Straumann [ITI], and Biomet 3i [3i] were selected. Peak torque of devices (5 in each subgroup was measured before and after autoclaving using a Tohnichi torque gauge. Descriptive statistical analysis was used and a repeated-measures ANOVA with type of device as a between-subject comparison was performed to assess the difference in accuracy among the three groups of spring-style mechanical torque devices after sterilization. A Bonferroni post hoc test was used to assess pairwise comparisons.Results: Before steam sterilization, all the tested devices stayed within 10% of their target values. After 100 sterilization cycles, results didn't show any significant difference between raw and absolute error values in the Nobel Biocare and ITI devices; however the results demonstrated an increase of error values in the 3i group (P < 0.05. Raw error

  4. Effect of steam sterilization inside the turbine chambers of dental turbines.

    Science.gov (United States)

    Andersen, H K; Fiehn, N E; Larsen, T

    1999-02-01

    It has been demonstrated that contamination of the insides of high-speed dental turbines occurs and that bacteria as well as viruses may remain infectious when expelled from such turbines during subsequent use. Consequently, it has been widely recommended that a high-speed turbine be sterilized after each patient. The purpose of this study was to evaluate the effect of steam autoclaving on a high-speed dental turbine with a contaminated turbine chamber. Streptococcus salivarius and endospores of Bacillus stearothermophilus were used as test organisms to determine the effectiveness of 4 different small non-vacuum autoclaves and one vacuum autoclave. The study demonstrated different efficiencies among the small non-vacuum autoclaves, the best showing close to a 6 log reduction of the test organisms inside the turbine chamber. When cleaning and lubrication of the high-speed dental turbine was carried out before autoclaving, this level of reduction was observed for all the examined non-vacuum autoclaves. It is concluded that cleaning before sterilization is essential for safe use of high-speed dental turbines and that small non-vacuum autoclaves should be carefully evaluated before being used for the reprocessing of hollow instruments such as high-speed turbines.

  5. Investigating steam penetration using thermometric methods in dental handpieces with narrow internal lumens during sterilizing processes with non-vacuum or vacuum processes.

    Science.gov (United States)

    Winter, S; Smith, A; Lappin, D; McDonagh, G; Kirk, B

    2017-12-01

    Dental handpieces are required to be sterilized between patient use. Vacuum steam sterilization processes with fractionated pre/post-vacuum phases or unique cycles for specified medical devices are required for hollow instruments with internal lumens to assure successful air removal. Entrapped air will compromise achievement of required sterilization conditions. Many countries and professional organizations still advocate non-vacuum sterilization processes for these devices. To investigate non-vacuum downward/gravity displacement, type-N steam sterilization of dental handpieces, using thermometric methods to measure time to achieve sterilization temperature at different handpiece locations. Measurements at different positions within air turbines were undertaken with thermocouples and data loggers. Two examples of widely used UK benchtop steam sterilizers were tested: a non-vacuum benchtop sterilizer (Little Sister 3; Eschmann, Lancing, UK) and a vacuum benchtop sterilizer (Lisa; W&H, Bürmoos, Austria). Each sterilizer cycle was completed with three handpieces and each cycle in triplicate. A total of 140 measurements inside dental handpiece lumens were recorded. The non-vacuum process failed (time range: 0-150 s) to reliably achieve sterilization temperatures within the time limit specified by the international standard (15 s equilibration time). The measurement point at the base of the handpiece failed in all test runs (N = 9) to meet the standard. No failures were detected with the vacuum steam sterilization type B process with fractionated pre-vacuum and post-vacuum phases. Non-vacuum downward/gravity displacement, type-N steam sterilization processes are unreliable in achieving sterilization conditions inside dental handpieces, and the base of the handpiece is the site most likely to fail. Copyright © 2017 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

  6. THE EFFECTS OF DIFFERENT STEAM-STERILIZATION PROGRAMS ON MATERIAL PROPERTIES OF POLY(L-LACTIDE)

    NARCIS (Netherlands)

    ROZEMA, FR; BOS, RRM; BOERING, G; VANASTEN, JAAM; NIJENHUIS, AJ; PENNINGS, AJ

    1991-01-01

    As-polymerized poly(L-lactide) test rods were sterilized by seven different specially designed computer-operated autoclaving programs. As a control, common hospital sterilization was performed. In all cases, the molecular weight decreased after sterilization. A short time high-temperature

  7. Computer modeling of a convective steam superheater

    Science.gov (United States)

    Trojan, Marcin

    2015-03-01

    Superheater is for generating superheated steam from the saturated steam from the evaporator outlet. In the case of pulverized coal fired boiler, a relatively small amount of ash causes problems with ash fouling on the heating surfaces, including the superheaters. In the convection pass of the boiler, the flue gas temperature is lower and ash deposits can be loose or sintered. Ash fouling not only reduces heat transfer from the flue gas to the steam, but also is the cause of a higher pressure drop on the flue gas flow path. In the case the pressure drop is greater than the power consumed by the fan increases. If the superheater surfaces are covered with ash than the steam temperature at the outlet of the superheater stages falls, and the flow rates of the water injected into attemperator should be reduced. There is also an increase in flue gas temperature after the different stages of the superheater. Consequently, this leads to a reduction in boiler efficiency. The paper presents the results of computational fluid dynamics simulations of the first stage superheater of both the boiler OP-210M using the commercial software. The temperature distributions of the steam and flue gas along the way they flow together with temperature of the tube walls and temperature of the ash deposits will be determined. The calculated steam temperature is compared with measurement results. Knowledge of these temperatures is of great practical importance because it allows to choose the grade of steel for a given superheater stage. Using the developed model of the superheater to determine its degree of ash fouling in the on-line mode one can control the activation frequency of steam sootblowers.

  8. An Improved Steam Injection Model with the Consideration of Steam Override

    Directory of Open Access Journals (Sweden)

    He Congge

    2017-01-01

    Full Text Available The great difference in density between steam and liquid during wet steam injection always results in steam override, that is, steam gathers on the top of the pay zone. In this article, the equation for steam override coefficient was firstly established based on van Lookeren’s steam override theory and then radius of steam zone and hot fluid zone were derived according to a more realistic temperature distribution and an energy balance in the pay zone. On this basis, the equation for the reservoir heat efficiency with the consideration of steam override was developed. Next, predicted results of the new model were compared with these of another analytical model and CMG STARS (a mature commercial reservoir numerical simulator to verify the accuracy of the new mathematical model. Finally, based on the validated model, we analyzed the effects of injection rate, steam quality and reservoir thickness on the reservoir heat efficiency. The results show that the new model can be simplified to the classic model (Marx-Langenheim model under the condition of the steam override being not taken into account, which means the Marx-Langenheim model is corresponding to a special case of this new model. The new model is much closer to the actual situation compared to the Marx-Langenheim model because of considering steam override. Moreover, with the help of the new model, it is found that the reservoir heat efficiency is not much affected by injection rate and steam quality but significantly influenced by reservoir thickness, and to ensure that the reservoir can be heated effectively, the reservoir thickness should not be too small.

  9. Sterile insect technique: A model for dose optimisation for improved sterile insect quality

    International Nuclear Information System (INIS)

    Parker, A.; Mehta, K.

    2007-01-01

    The sterile insect technique (SIT) is an environment-friendly pest control technique with application in the area-wide integrated control of key pests, including the suppression or elimination of introduced populations and the exclusion of new introductions. Reproductive sterility is normally induced by ionizing radiation, a convenient and consistent method that maintains a reasonable degree of competitiveness in the released insects. The cost and effectiveness of a control program integrating the SIT depend on the balance between sterility and competitiveness, but it appears that current operational programs with an SIT component are not achieving an appropriate balance. In this paper we discuss optimization of the sterilization process and present a simple model and procedure for determining the optimum dose. (author) [es

  10. Modelling the horizontal steam generator with APROS

    Energy Technology Data Exchange (ETDEWEB)

    Ylijoki, J. [VTT Energy, Espoo (Finland); Palsinajaervi, C.; Porkholm, K. [IVO International Ltd, Vantaa (Finland)

    1995-12-31

    In this paper the capability of the five- and six-equation models of the simulation code APROS to simulate the behaviour of the horizontal steam generator is discussed. Different nodalizations are used in the modelling and the results of the stationary state runs are compared. Exactly the same nodalizations have been created for the five- and six-equation models. The main simulation results studied in this paper are void fraction and mass flow distributions in the secondary side of the steam generator. It was found that quite a large number of simulation volumes is required to simulate the distributions with a reasonable accuracy. The simulation results of the different models are presented and their validity is discussed. (orig.). 4 refs.

  11. Comparison of the effects of gamma irradiation and steam sterilization on Southern pine sapwood

    Science.gov (United States)

    Simon Curling; Jerrold E. Winandy

    2008-01-01

    Gamma irradiation is a commonly used method of sterilization of wood specimens prior to decay testing. As part of a larger series of studies, an investigation was made into the effects of gamma irradiation on flexural bending strength properties and its corresponding relationship to changes in lignin and hemicellulosic contents of wood after exposure to various dose...

  12. Crosslinked agarose encapsulated sorbents resistant to steam sterilization. Preparation and mechanical properties

    NARCIS (Netherlands)

    de Koning, H. W.; Chamuleau, R. A.; Bantjes, A.

    1984-01-01

    The application of agarose in hemoperfusion is hampered by the lack of a suitable sterilization method. A technique has been developed for the crosslinking of agarose encapsulated sorbents by the reaction with 1,3-dichloro-2-propanol (DCP) under strong alkaline conditions. A twofold molar excess of

  13. Hybrid model of steam boiler

    International Nuclear Information System (INIS)

    Rusinowski, Henryk; Stanek, Wojciech

    2010-01-01

    In the case of big energy boilers energy efficiency is usually determined with the application of the indirect method. Flue gas losses and unburnt combustible losses have a significant influence on the boiler's efficiency. To estimate these losses the knowledge of the operating parameters influence on the flue gases temperature and the content of combustible particles in the solid combustion products is necessary. A hybrid model of a boiler developed with the application of both analytical modelling and artificial intelligence is described. The analytical part of the model includes the balance equations. The empirical models express the dependence of the flue gas temperature and the mass fraction of the unburnt combustibles in solid combustion products on the operating parameters of a boiler. The empirical models have been worked out by means of neural and regression modelling.

  14. Model Predictive Control for Ethanol Steam Reformers

    OpenAIRE

    Li, Mingming

    2014-01-01

    This thesis firstly proposes a new approach of modelling an ethanol steam reformer (ESR) for producing pure hydrogen. Hydrogen has obvious benefits as an alternative for feeding the proton exchange membrane fuel cells (PEMFCs) to produce electricity. However, an important drawback is that the hydrogen distribution and storage have high cost. So the ESR is regarded as a way to overcome these difficulties. Ethanol is currently considered as a promising energy source under the res...

  15. Modelling of UO2 oxidation in steam

    International Nuclear Information System (INIS)

    Brito, A.C.; Iglesias, F.C.; Liu, Y.

    1996-01-01

    A computer model has been developed for calculating oxidation of UO 2 at high temperatures in steam oxidising conditions. Several methods to calculate the partial pressure of oxygen in the fuel and in the environment surrounding the fuel are available. The various methodologies have been compared and the best models have been compiled into a computer model which will be implemented into fuel thermal/mechanical behaviour codes such as FACTAR 2.0 (LOECI) and ELESIM/ELOCA. Calculations from the computer model have been compared to experimental results. The calculated oxidation reaction kinetics are in good agreement with the experimental data. (author)

  16. Steam condensation modelling in aerosol codes

    International Nuclear Information System (INIS)

    Dunbar, I.H.

    1986-01-01

    The principal subject of this study is the modelling of the condensation of steam into and evaporation of water from aerosol particles. These processes introduce a new type of term into the equation for the development of the aerosol particle size distribution. This new term faces the code developer with three major problems: the physical modelling of the condensation/evaporation process, the discretisation of the new term and the separate accounting for the masses of the water and of the other components. This study has considered four codes which model the condensation of steam into and its evaporation from aerosol particles: AEROSYM-M (UK), AEROSOLS/B1 (France), NAUA (Federal Republic of Germany) and CONTAIN (USA). The modelling in the codes has been addressed under three headings. These are the physical modelling of condensation, the mathematics of the discretisation of the equations, and the methods for modelling the separate behaviour of different chemical components of the aerosol. The codes are least advanced in area of solute effect modelling. At present only AEROSOLS/B1 includes the effect. The effect is greater for more concentrated solutions. Codes without the effect will be more in error (underestimating the total airborne mass) the less condensation they predict. Data are needed on the water vapour pressure above concentrated solutions of the substances of interest (especially CsOH and CsI) if the extent to which aerosols retain water under superheated conditions is to be modelled. 15 refs

  17. Influence of sterilization on the mineralization of titanium implants induced by incubation in various biological model fluids.

    Science.gov (United States)

    Serro, A P; Saramago, B

    2003-11-01

    The aim of this work was to investigate the effect of the sterilization processes on the mineralization of titanium implants induced by incubation in various biological model fluids. Titanium samples were submitted to the following sterilization processes used for implant materials: steam autoclaving, glow discharge Ar plasma treatment and gamma-irradiation. The modification of the treated surfaces was evaluated by contact angle determinations, X-ray photoelectron spectroscopy (XPS), laser profilometry and X-ray diffraction. The most significant modifications were detected on the wettability: while the samples treated with Ar plasma became highly hydrophilic (water contact angle approximately 0 degrees), gamma-irradiation and steam sterilization induced an increase in the hydrophobicity. After being sterilized, the samples were incubated for one week in three biological model fluids: Hanks' Balanced Salt Solution, Kokubo's simulated body fluid (SBF) and a fluid, designated by SBF0, with the same composition of SBF but without buffer TRIS. The level of mineralization of the incubated Ti samples, assessed by dynamic contact angle analysis, scanning electron microscopy, electron dispersive spectroscopy and XPS, indicated that the early stages of mineralization are essentially independent of the sterilization method. In contrast, the incubating fluid plays a determinant role, SBFO being the most efficient medium for biomineralization of titanium.

  18. Modifications of steam condensation model implemented in commercial solver

    Science.gov (United States)

    Sova, Libor; Jun, Gukchol; ŠÅ¥astný, Miroslav

    2017-09-01

    Nucleation theory and droplet grow theory and methods how they are incorporated into numerical solvers are crucial factors for proper wet steam modelling. Unfortunately, they are still covered by cloud of uncertainty and therefore some calibration of these models according to reliable experimental results is important for practical analyses of steam turbines. This article demonstrates how is possible to calibrate wet steam model incorporated into commercial solver ANSYS CFX.

  19. Modeling and Simulation of U-tube Steam Generator

    Science.gov (United States)

    Zhang, Mingming; Fu, Zhongguang; Li, Jinyao; Wang, Mingfei

    2018-03-01

    The U-tube natural circulation steam generator was mainly researched with modeling and simulation in this article. The research is based on simuworks system simulation software platform. By analyzing the structural characteristics and the operating principle of U-tube steam generator, there are 14 control volumes in the model, including primary side, secondary side, down channel and steam plenum, etc. The model depends completely on conservation laws, and it is applied to make some simulation tests. The results show that the model is capable of simulating properly the dynamic response of U-tube steam generator.

  20. Evaluation of rapid readout biological indicators for 132 degrees C gravity and 132 degrees C vacuum-assisted steam sterilization cycles using a new automated fluorescent reader.

    Science.gov (United States)

    Alfa, Michelle J; Olson, Nancy; DeGagne, Pat; Jackson, Michele

    2002-07-01

    The primary objective of this study was to evaluate fluorescent readout results of Attest 1291 Biological Indicators (BIs) (3M Health Care, St. Paul, MN) and Attest 1296 BI test packs (containing Attest 1292 BIs) using full and fractional cycles compared with the growth data when prolonged incubation (7 days) was included. Gravity displacement and vacuum-assisted steam sterilization cycles were evaluated. A secondary objective of this study was to evaluate the new automated rapid fluorescent reader (Attest 290 Auto Reader). The rapid readout BIs for gravity displacement and vacuum-assisted steam autoclave cycles at 132 degrees C were processed using full (4 minutes) and four fractional cycles that provided 30% to 80% positive results for growth after 24 hours of incubation (48 hours of incubation for Attest 1292 BIs from the Attest 1296 test packs). Sixty of each type of BI were tested for each cycle (300 of each BI type in total). For all full steam sterilization cycles, results of the rapid fluorescent readout and the 24-hour, 48-hour, and 7-day growth tests were negative for all Attest 1291 and 1292 BIs tested. For all fractional cycles, the 24- and 48-hour growth results for the Attest 1291 and 1292 BIs, respectively, were the same as the 7-day growth results. The fractional cycle data indicated that fluorescent rapid readout was a more sensitive indicator than growth. There were rare (0.9%) false-negative results for BIs under fractional cycle conditions and these all correlated with short fractional cycle exposure times. The fluorescent rapid readout results of the 1291 BIs and 1296 BI test packs reliably predict both 24- and 48-hour and 7-day growth. These data support the value of rapid readout BIs for sterilizer monitoring for both the vacuum-assisted and the gravity displacement steam sterilization cycles. The new automated reader requires less manipulation of the BI and makes monitoring user friendly and less prone to user errors.

  1. Effect of dry heat and steam sterilization on load-deflection characteristics of β-titanium wires: An in vitro study

    Science.gov (United States)

    Alavi, Shiva; Sinaee, Neda

    2012-01-01

    Background: Sterilization techniques could affect the characteristics of orthodontic wires. The aim of the present study was to evaluate the effect of steam and dry heat sterilization techniques on load-deflection behavior of five types of β-titanium alloy wires. Materials and Methods: The samples consisted of 30 straight lengths of five types of β-titanium alloy wires: Titanium Molybdenum Alloy (TMA) Low Friction (TMAL), TMA Low Friction Colored (HONE), Resolve (RES), BetaForce (BETA), and BETA CNA (CNA). Thirty wire segments were divided into three groups of 10. Group 1 was the control group and the group 2 samples were sterilized by dry heat in an oven (60 minutes at 160°C) and group 3 by steam in an autoclave (15 minutes at 121°C). Then all the wire samples underwent a three-point bending test in a testing machine to evaluate load-deflection properties. Data was analyzed by repeated measures ANOVA and Scheffé's test (α = 0.05). Results: The results showed that dry heat sterilization significantly increased force levels during both loading and unloading of CNA, BETA and RES and during loading of HONE (P 0.05). Conclusion: It appears dry heat sterilization increases stiffness of RES, BETA, CNA and HONE but autoclave sterilization did not have any effect on load-deflection characteristics of most of the β-titanium wires tested, indicating that clinicians who want to provide maximum safety for their patients can autoclave TMAL, RES and CNA before applying them. PMID:23559917

  2. Model for transient simulation in a PWR steam circuit

    International Nuclear Information System (INIS)

    Mello, L.A. de.

    1982-11-01

    A computer code (SURF) was developed and used to simulate pressure losses along the tubes of the main steam circuit of a PWR nuclear power plant, and the steam flow through relief and safety valves when pressure reactors its thresholds values. A thermodynamic model of turbines (high and low pressure), and its associated components are simulated too. The SURF computer code was coupled to the GEVAP computer code, complementing the simulation of a PWR nuclear power plant main steam circuit. (Author) [pt

  3. Electron beam sterilization for dishes

    International Nuclear Information System (INIS)

    Deren, Wang; Meizhen, Fang

    1995-01-01

    Modern biological science often needs various fine strike devices which are often made from non-toxic transparent plastic. The application of high temperature steam to the sterilization as a traditional methods often causes deformation and colour change. When chemicals are applied to the sterilization residure of chemical grain often causes toxicity. Only application of radiation to the sterilization can overcome this faults and carry out with sterility assurance at room temperature. In this research 1.3 MeV electron beam coming from Model JJ-2 accelerator was applied for sterilization to 96-well tissue culture plates. After clean packaging the plates were irradiated with 31.7 XGy and operational voltage 1.3 MeV and 100 μA on the PY device. Repeated tests demonstrate that the products are sterile. The output is 2 x 10 5 pieces for each year. (author)

  4. Developing a Conceptual Model of STEAM Teaching Practices

    Science.gov (United States)

    Quigley, Cassie F.; Herro, Dani; Jamil, Faiza M.

    2017-01-01

    STEAM, where the "A" represents arts and humanities, is considered a transdisciplinary learning process that has the potential to increase diverse participation in science, technology, engineering, and math (STEM) fields. However, a well-defined conceptual model that clearly articulates essential components of the STEAM approach is…

  5. Numerical modeling of secondary side thermohydraulics of horizontal steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Melikhov, V.I.; Melikhov, O.I.; Nigmatulin, B.I. [Research and Engineering Centre of LWR Nuclear Plants Safety, Moscow (Russian Federation)

    1995-12-31

    A mathematical model for the transient three-dimensional secondary side thermal hydraulics of the horizontal steam generator has been developed. The calculations of the steam generator PGV-1000 and PGV-4 nominal regimes and comparison of numerical and experimental results have been carried out. 7 refs.

  6. Modelling of a Coil Steam Generator for CSP applications

    DEFF Research Database (Denmark)

    Pelagotti, Leonardo; Sørensen, Kim; Condra, Thomas Joseph

    2014-01-01

    The project investigates a new design for a CSP plant steam generation system, the Coil Steam Generator (CSG). This system allows faster start-ups and therefore higher daily energy production from the Sun. An analytical thermodynamic simulation model of the evaporator and a mechanical analysis...

  7. Evaluation of a new rapid readout biological indicator for use in 132°C and 135°C vacuum-assisted steam sterilization cycles.

    Science.gov (United States)

    Schneider, Philip M

    2014-02-01

    Sterilization is a process that cannot be inspected or tested in a practical manner to assure that all microorganisms have been inactivated. The process must therefore be validated for all of the specific items processed or monitored on a per cycle basis. A new, faster rapid readout biological indicator (RRBI) has been developed for use in 132°C and 135°C vacuum-assisted steam sterilization cycles. The aim of this study was to evaluate the performance of this new 1-hour readout RRBI at 132°C in side-by-side testing with an existing 3-hour readout RRBI and also evaluate the performance of the new RRBI in 135°C cycles. Readout responses of 1 hour (fluorescent) and 48 hours and 7 days (growth) of the new RRBI were compared with 3-hour, 48-hour, and 7-day readouts of the 3-hour RRBI following exposures in 132°C cycles using a highly controlled test vessel, ie, a steam resistometer. Additional testing of the 1-hour RRBIs was also performed in 135°C cycles. The number and percentage of fluorescent-positive 1-hour RRBIs were virtually identical to those of the 3-hour RRBIs after 1 and 3 hours of incubation, respectively. Testing of the 1-hour RRBI in 135°C cycles paralleled the results of the testing at 132°C but with the expected shorter exposure times. The results of this study suggest that the 1-hour RRBI is equivalent to the 3-hour RRBI and would be suitable for use in monitoring dynamic air removal steam sterilization cycles at both 132°C and 135°C per recommended practice guidelines. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  8. An Improved Steam Injection Model with the Consideration of Steam Override

    OpenAIRE

    He , Congge; Mu , Longxin; Fan , Zifei; Xu , Anzhu; Zeng , Baoquan; Ji , Zhongyuan; Han , Haishui

    2017-01-01

    International audience; The great difference in density between steam and liquid during wet steam injection always results in steam override, that is, steam gathers on the top of the pay zone. In this article, the equation for steam override coefficient was firstly established based on van Lookeren’s steam override theory and then radius of steam zone and hot fluid zone were derived according to a more realistic temperature distribution and an energy balance in the pay zone. On this basis, th...

  9. Steam injection for heavy oil recovery: Modeling of wellbore heat efficiency and analysis of steam injection performance

    International Nuclear Information System (INIS)

    Gu, Hao; Cheng, Linsong; Huang, Shijun; Li, Bokai; Shen, Fei; Fang, Wenchao; Hu, Changhao

    2015-01-01

    Highlights: • A comprehensive mathematical model was established to estimate wellbore heat efficiency of steam injection wells. • A simplified approach of predicting steam pressure in wellbores was proposed. • High wellhead injection rate and wellhead steam quality can improve wellbore heat efficiency. • High wellbore heat efficiency does not necessarily mean good performance of heavy oil recovery. • Using excellent insulation materials is a good way to save water and fuels. - Abstract: The aims of this work are to present a comprehensive mathematical model for estimating wellbore heat efficiency and to analyze performance of steam injection for heavy oil recovery. In this paper, we firstly introduce steam injection process briefly. Secondly, a simplified approach of predicting steam pressure in wellbores is presented and a complete expression for steam quality is derived. More importantly, both direct and indirect methods are adopted to determine the wellbore heat efficiency. Then, the mathematical model is solved using an iterative technique. After the model is validated with measured field data, we study the effects of wellhead injection rate and wellhead steam quality on steam injection performance reflected in wellbores. Next, taking cyclic steam stimulation as an example, we analyze steam injection performance reflected in reservoirs with numerical reservoir simulation method. Finally, the significant role of improving wellbore heat efficiency in saving water and fuels is discussed in detail. The results indicate that we can improve the wellbore heat efficiency by enhancing wellhead injection rate or steam quality. However, high wellbore heat efficiency does not necessarily mean satisfactory steam injection performance reflected in reservoirs or good performance of heavy oil recovery. Moreover, the paper shows that using excellent insulation materials is a good way to save water and fuels due to enhancement of wellbore heat efficiency

  10. Numerical investigation of mass transfer in the flow path of the experimental model of the PGV-1500 steam generator's steam receiving section with two steam nozzles

    Science.gov (United States)

    Golibrodo, L. A.; Krutikov, A. A.; Nadinskii, Yu. N.; Nikolaeva, A. V.; Skibin, A. P.; Sotskov, V. V.

    2014-10-01

    The hydrodynamics of working medium in the steam volume model implemented in the experimental setup constructed at the Leipunskii Institute for Physics and Power Engineering was simulated for verifying the procedure of calculating the velocity field in the steam space of steam generators used as part of the reactor plants constructed on the basis of water-cooled water-moderated power-generating reactors (VVER). The numerical calculation was implemented in the environment of the STAR-CCM+ software system with its cross verification in the STAR-CD and ANSYS CFX software systems. The performed numerical investigation served as a basis for substantiating the selection of the computation code and parameters for constructing the computer model of the steam receiving device of the PGV-1500 steam generator experimental model, such as the quantization scheme, turbulence model, and mesh model.

  11. Modeling of steam distillation mechanism during steam injection process using artificial intelligence.

    Science.gov (United States)

    Daryasafar, Amin; Ahadi, Arash; Kharrat, Riyaz

    2014-01-01

    Steam distillation as one of the important mechanisms has a great role in oil recovery in thermal methods and so it is important to simulate this process experimentally and theoretically. In this work, the simulation of steam distillation is performed on sixteen sets of crude oil data found in the literature. Artificial intelligence (AI) tools such as artificial neural network (ANN) and also adaptive neurofuzzy interference system (ANFIS) are used in this study as effective methods to simulate the distillate recoveries of these sets of data. Thirteen sets of data were used to train the models and three sets were used to test the models. The developed models are highly compatible with respect to input oil properties and can predict the distillate yield with minimum entry. For showing the performance of the proposed models, simulation of steam distillation is also done using modified Peng-Robinson equation of state. Comparison between the calculated distillates by ANFIS and neural network models and also equation of state-based method indicates that the errors of the ANFIS model for training data and test data sets are lower than those of other methods.

  12. CANDU 6 steam generator thermalhydraulic modeling and simulation

    International Nuclear Information System (INIS)

    Zahedi, P.; Borairi, M.

    2009-01-01

    The main objective of this paper is to describe the process of accurately modeling the dynamic behavior of CANada Deuterium Uranium 6 (CANDU 6) steam generator and its control algorithm. The mathematical model of the steam generator was developed mainly through differential equations calculated from the physical properties of the components. In addition, empirical modeling techniques were utilized in order to incorporate more complex properties of steam generators. The controller design and resulting controller performance on the actual plant are both strongly dependent on the accuracy of the mathematical model used to describe the plant. During power manoeuvrings, the level control in a steam generator is complicated by the thermal reverse effects known as 'shrink and swell'. This non-linear non-minimum phase characteristic of the steam generators is most challenging to model. Based on various recent publications, the root cause of the deficiencies in model-based controller designs is the fact that the 'shrink and swell' phenomenon is not captured by the plant model. The model developed in this project captures this phenomenon and clearly presents the adverse effect of such characteristic in the performance of conventional controllers. The resulting mathematical model developed in this project is implemented in Simulink, a graphical block diagramming tool offered by MATLAB. In addition to the plant model, the complete control algorithm of the CANDU 6 steam generator is modeled in this project. This model duplicates the actual control strategy applied in the existing steam generators in order to create a realistic interaction between the plant and its control algorithm. The control model is developed in discrete-time in order to accurately simulate the output of the digital controller. The analog model of the plant is dynamically integrated with the digital control model in the Simulink environment creating a realistic presentation of the actual communication

  13. Galaxy Formation in Sterile Neutrino Dark Matter Models

    Science.gov (United States)

    Menci, N.; Grazian, A.; Lamastra, A.; Calura, F.; Castellano, M.; Santini, P.

    2018-02-01

    We investigate galaxy formation in models with dark matter (DM) constituted by sterile neutrinos. Given their large parameter space, defined by the combinations of sterile neutrino mass {m}ν and mixing parameter {\\sin }2(2θ ) with active neutrinos, we focus on models with {m}ν =7 {keV}, consistent with the tentative 3.5 keV line detected in several X-ray spectra of clusters and galaxies. We consider (1) two resonant production models with {\\sin }2(2θ )=5 × {10}-11 and {\\sin }2(2θ )=2 × {10}-10, to cover the range of mixing parameters consistent with the 3.5 keV line; (2) two scalar-decay models, representative of the two possible cases characterizing such a scenario: a freeze-in and a freeze-out case. We also consider thermal warm DM with particle mass {m}X=3 {keV}. Using a semianalytic model, we compare the predictions for the different DM scenarios with a wide set of observables. We find that comparing the predicted evolution of the stellar mass function, the abundance of satellites of Milky Way–like galaxies, and the global star formation history of galaxies with observations does not allow us to disentangle the effects of the baryonic physics from those related to the different DM models. On the other hand, the distribution of the stellar-to-halo mass ratios, the abundance of faint galaxies in the UV luminosity function at z≳ 6, and the specific star formation and age distribution of local, low-mass galaxies constitute potential probes for the DM scenarios considered. We discuss how future observations with upcoming facilities will enable us to rule out or to strongly support DM models based on sterile neutrinos.

  14. Mathematical modelling of steam generator and design of temperature regulator

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanovic, S.S. [EE Institute Nikola Tesla, Belgrade (Yugoslavia)

    1999-07-01

    The paper considers mathematical modelling of once-through power station boiler and numerical algorithm for simulation of the model. Fast and numerically stable algorithm based on the linearisation of model equations and on the simultaneous solving of differential and algebraic equations is proposed. The paper also presents the design of steam temperature regulator by using the method of projective controls. Dynamic behaviour of the system closed with optimal linear quadratic regulator is taken as the reference system. The desired proprieties of the reference system are retained and solutions for superheated steam temperature regulator are determined. (author)

  15. Phenomenological study of extended seesaw model for light sterile neutrino

    Energy Technology Data Exchange (ETDEWEB)

    Nath, Newton [Physical Research Laboratory,Navarangpura, Ahmedabad 380 009 (India); Indian Institute of Technology,Gandhinagar, Ahmedabad-382424 (India); Ghosh, Monojit [Department of Physics, Tokyo Metropolitan University,Hachioji, Tokyo 192-0397 (Japan); Goswami, Srubabati [Physical Research Laboratory,Navarangpura, Ahmedabad 380 009 (India); Gupta, Shivani [Center of Excellence for Particle Physics (CoEPP), University of Adelaide,Adelaide SA 5005 (Australia)

    2017-03-14

    We study the zero textures of the Yukawa matrices in the minimal extended type-I seesaw (MES) model which can give rise to ∼ eV scale sterile neutrinos. In this model, three right handed neutrinos and one extra singlet S are added to generate a light sterile neutrino. The light neutrino mass matrix for the active neutrinos, m{sub ν}, depends on the Dirac neutrino mass matrix (M{sub D}), Majorana neutrino mass matrix (M{sub R}) and the mass matrix (M{sub S}) coupling the right handed neutrinos and the singlet. The model predicts one of the light neutrino masses to vanish. We systematically investigate the zero textures in M{sub D} and observe that maximum five zeros in M{sub D} can lead to viable zero textures in m{sub ν}. For this study we consider four different forms for M{sub R} (one diagonal and three off diagonal) and two different forms of (M{sub S}) containing one zero. Remarkably we obtain only two allowed forms of m{sub ν} (m{sub eτ}=0 and m{sub ττ}=0) having inverted hierarchical mass spectrum. We re-analyze the phenomenological implications of these two allowed textures of m{sub ν} in the light of recent neutrino oscillation data. In the context of the MES model, we also express the low energy mass matrix, the mass of the sterile neutrino and the active-sterile mixing in terms of the parameters of the allowed Yukawa matrices. The MES model leads to some extra correlations which disallow some of the Yukawa textures obtained earlier, even though they give allowed one-zero forms of m{sub ν}. We show that the allowed textures in our study can be realized in a simple way in a model based on MES mechanism with a discrete Abelian flavor symmetry group Z{sub 8}×Z{sub 2}.

  16. Physical and statistical models for steam generator clogging diagnosis

    CERN Document Server

    Girard, Sylvain

    2014-01-01

    Clogging of steam generators in nuclear power plants is a highly sensitive issue in terms of performance and safety and this book proposes a completely novel methodology for diagnosing this phenomenon. It demonstrates real-life industrial applications of this approach to French steam generators and applies the approach to operational data gathered from French nuclear power plants. The book presents a detailed review of in situ diagnosis techniques and assesses existing methodologies for clogging diagnosis, whilst examining their limitations. It also addresses numerical modelling of the dynamic

  17. Modeling of Steam Distillation Mechanism during Steam Injection Process Using Artificial Intelligence

    Directory of Open Access Journals (Sweden)

    Amin Daryasafar

    2014-01-01

    neurofuzzy interference system (ANFIS are used in this study as effective methods to simulate the distillate recoveries of these sets of data. Thirteen sets of data were used to train the models and three sets were used to test the models. The developed models are highly compatible with respect to input oil properties and can predict the distillate yield with minimum entry. For showing the performance of the proposed models, simulation of steam distillation is also done using modified Peng-Robinson equation of state. Comparison between the calculated distillates by ANFIS and neural network models and also equation of state-based method indicates that the errors of the ANFIS model for training data and test data sets are lower than those of other methods.

  18. An improved steam generator model for the SASSYS code

    International Nuclear Information System (INIS)

    Pizzica, P.A.

    1989-01-01

    A new steam generator model has been developed for the SASSYS computer code, which analyzes accident conditions in a liquid metal cooled fast reactor. It has been incorporated into the new SASSYS balance-of-plant model but it can also function on a stand-alone basis. The steam generator can be used in a once-through mode, or a variant of the model can be used as a separate evaporator and a superheater with recirculation loop. The new model provides for an exact steady-state solution as well as the transient calculation. There was a need for a faster and more flexible model than the old steam generator model. The new model provides for more detail with its multi-mode treatment as opposed to the previous model's one node per region approach. Numerical instability problems which were the result of cell-centered spatial differencing, fully explicit time differencing, and the moving boundary treatment of the boiling crisis point in the boiling region have been reduced. This leads to an increase in speed as larger time steps can now be taken. The new model is an improvement in many respects. 2 refs., 3 figs

  19. Studying the process following small steam leaks into sodium using the counterflow steam generator model

    International Nuclear Information System (INIS)

    Kozlov, F.A.; Sergeev, G.P.; Volchkov, L.G.; Sednev, A.P.; Makarov, V.M.; Tonov, B.I.

    1982-01-01

    Peculiarities of hydrodynamic conditions arising in a defective tube of the counterflow steam generator following water leaks into the sodium have been studied using suitable models made of 12Kh18N10T and 10Kh2M steels. Data on the rate of the steam leaks spontaneous evolution and corrosive effect on the opposite wall of the tube are obtained as a function of the leak position and sizes. On the basis of the analysis of the experimental results a conclusion is drawn that two stages are distinguished during the leak spontaneous evolution. Changes in the leak sizes occur gradually and remain small during the first stage. The leak increases quickly and exceeds the initial level more than by two orders during the second stage. The results of metallographlic analysis of the tube steels carried out after the experiments confirm the earlier obtianed data on the presence of inter. granular interaction in 12Kh18N10T steel following the effect of of the water-to-sodium reaction products, and on a preferentially frontal type of 10Kh2M steel corrosion

  20. Sterilization of health care products - Chemical indicators - Part 4: Class 2 indicators as an alternative to the Bowie and Dick-type test for detection of steam penetration. 2. ed.

    International Nuclear Information System (INIS)

    2007-01-01

    This part of ISO 11140 specifies the performance of the indicator system in combination with the test load with which it is intended to be used. The test load may be presented with the indicator system already incorporated and intended for single use, or it may be intended for multiple use with a new indicator system to be inserted prior to each use. The indicator for which the performance is specified in this part of ISO 11140 is intended to indicate when steam penetration has been inadequate. The performance of the indicator specified in this part of ISO 11140 should be equivalent, but not necessarily identical, to the performance obtained in the Bowie and Dick-type test as described in ISO 11140-3. Equivalence should be regarded as providing a similar response to steam penetration with any differences being predictable and such that the necessary level of assurance of satisfactory steam penetration is provided. An indicator meeting this specification is not intended to identify which of the potential causes of poor steam penetration was responsible for the failure indicated by the test. This part of ISO 11140 specifies the performance for a Class 2 indicator to be used as an alternative to the Bowie and Dick-type test for steam sterilizers for wrapped health care goods (instruments, etc., and porous loads). The Bowie and Dick-type test is used for routine testing of steam sterilizers and validation of steam sterilization processes. An indicator complying with this part of ISO 11140 incorporates a specified material which is used as a test load. This test load may, or may not, be re-usable. This part of ISO 11140 does not specify requirements for the test load, but specifies the performance of the indicator in combination with the test load with which it is intended to be used. The indicator specified in this part of ISO 11140 is intended to identify poor steam penetration but does not necessarily indicate the cause of this poor steam penetration. This part of

  1. Measuring non-condensable gases in steam.

    Science.gov (United States)

    van Doornmalen, J P C M; Kopinga, K

    2013-11-01

    In surgery, medical devices that are used should be sterilized. To obtain surface steam sterilization conditions, not only in the sterilizer chamber itself but also in the loads to be sterilized, the amount of non-condensable gases (NCGs), for instance air, should be very low. Even rather small fractions of NCGs (below 1%) seriously hamper steam penetration in porous materials or devices with hollow channels (e.g., endoscopes). A recently developed instrument which might detect the presence of residual NCGs in a reliable and reproducible way is the 3M(TM) Electronic Test System (ETS). In this paper, a physical model is presented that describes the behavior of this instrument. This model has been validated by experiments in which known fractions of NCGs were introduced in a sterilizer chamber in which an ETS was placed. Despite several approximations made in the model, a good agreement is found between the model predictions and the experimental results. The basic principle of the ETS, measuring the heat transfer by condensation on a cooled surface, permits a very sensitive detection of NCGs in harsh environments like water vapor at high temperatures and pressures. Our model may serve to develop adapted and optimized versions of this instrument for use outside the field of sterilization, e.g., in heat exchangers based on steam condensation.

  2. Mathematical modeling of a steam generator for sensor fault detection

    International Nuclear Information System (INIS)

    Prock, J.

    1988-01-01

    A dynamic model for a nuclear power plant steam generator (vertical, preheated, U-tube recirculation-type) is formulated as a sixth-order nonlinear system. The model integrates nodal mass and energy balances for the primary water, the U-tube metal and the secondary water and steam. The downcomer flow is determined by a static balance of momentum. The mathematical system is solved using transient input data from the Philippsburg 2 (FRG) nuclear power plant. The results of the calculation are compared with actual measured values. The proposed model provides a low-cost tool for the automatic control and simulation of the steam generating process. The ''parity-space'' algorithm is used to demonstrate the applicability of the mathematical model for sensor fault detection and identification purposes. This technique provides a powerful means of generating temporal analytical redundancy between sensor signals. It demonstrates good detection rates of sensor errors using relatively few steps of scanning time and allows the reconfiguration of faulty signals. (author)

  3. Linear stability model for the once-through steam generator

    International Nuclear Information System (INIS)

    Kim, Y. S.; Kim, O. K.; Wi, M. H.; A, J. H.

    2001-01-01

    A linear stability model was developed to evaluate the stability of the once-through steam generator. Using the perturbation and Laplace transformation the governing equations were transformed to perturbed linear equations whose solutions are used to calculate pertubed pressure drop relations. An applicable algorithm for numercial analysis was adopted and draft version of a computer code named SGSTAR was developed. Using the SGSTAR a test calculation on the density wave instability has been conducted

  4. Modelling studies of horizontal steam generator PGV-1000 with Cathare

    Energy Technology Data Exchange (ETDEWEB)

    Karppinen, I. [VTT Energy, Espoo (Finland)

    1995-12-31

    To perform thermal-hydraulic studies applied to nuclear power plants equipped with VVER, a program of qualification and assessment of the CATHARE computer code is in progress at the Institute of Protection and Nuclear Safety (IPSN). In this paper studies of modelling horizontal steam generator of VVER-1000 with the CATHARE computer code are presented. Steady state results are compared with measured data from the fifth unit of Novovoronezh nuclear power plant. (orig.). 10 refs.

  5. Energy analysis in sterilization process of food

    International Nuclear Information System (INIS)

    Lee, Dong Sun; Pyun, Yu Ryang

    1986-01-01

    A procedure was developed for predicting energy consumption of batch type thermal processing of food. From mass and energy balance equations various energy usages or losses were estimated for steam sterilization of model food system in No.301-7 can (Φ74.1 x 113.0mm) at three different temperatures. Selected models were 5 % bentonite solution for conductive food and tap water for convective food. Total steam or energy consumption was higher at 110 deg C than at two other higher temperatures (121 deg C and 130 deg C). High energy consumption at low sterilization temperature was mainly due to high bleeding steam energy and convective and radiative heat losses. Thermal energy efficiency was also disscussed. (Author)

  6. An improved steam generator model for the SASSYS code

    International Nuclear Information System (INIS)

    Pizzica, P.A.

    1989-01-01

    A new steam generator model has been developed for the SASSYS computer code, which analyzes accident conditions in a liquid-metal-cooled fast reactor. It has been incorporated into the new SASSYS balance-of-plant model, but it can also function as a stand-alone model. The model provides a full solution of the steady-state condition before the transient calculation begins for given sodium and water flow rates, inlet and outlet sodium temperatures, and inlet enthalpy and region lengths on the water side

  7. Comparative effect of steam and gamma irradiation sterilization of sawdust compost on the yield, nutrient and shelf-life of Pleurotus ostreatus (Jacq. Ex.Fr) Kummer stored in two different packaging materials

    International Nuclear Information System (INIS)

    Kortei, J. N. K.

    2015-06-01

    influence of radiation on drying rate of oyster mushrooms were determined by five non- linear regression models (Lewis, Page, Henderson and Pabis, Diffussion and Wang and Singh by the estimation of R 2 , X 2 and RMSE). The total phenolic contents, flavonoids and free radical scavenging activity DPPH (2, 2' - diphenyl- 1- picrylhydrazyl) as sources of natural antioxidant of stored mushroom in polypropylene and polythene packs were determined using aqueous, ethanol and methanol extracts by Folin- Ciocalteau method. Finally, the influence of gamma irradiation on the colour characteristics were determined by the Hunter L * a* b* and Browning Index (BI) method while textural characteristics were determined mechanically by measuring Texture Hardness (kgf), Fracturability (N), Cohesiveness, Chewiness (N), Springiness (mm), Gumminess, Adhesiveness (kgf.s) and Resilience of fresh, dry and rehydrated mushrooms. The mechanical estimation to textural characters obtained were compared mean scores on 9-point Hedonic scale of sensory acceptability attributes (appearance, colour, aroma, taste, mouthfeel and overall acceptability of coded samples in two packaging containers. The survey demonstrated the popularity of drum (moist heat) technique of sterilization in Ghana. Majority (64%) of the respondents were dissatisfied with the method of sterilization of compost and spawn substrate with 36% indicated the method was alright by them. Majority (82%) of the respondents have never heard of sterilization of food or mushroom by gamma irradiation technique. Because of the high contamination rate of the steam sterilized compost and spawn substrate, the farmers indicated the need to achieve better sterilization for these starting material for mushroom cultivation. Drying was selected as the most popular preservation method as the fresh fruiting bodies have short shelf-life and P. ostreatus was found to be the most preferred mushroom followed by the termite mushroom (Termitomyces sp.). The

  8. Modelling local chemistry in PWR steam generator crevices

    International Nuclear Information System (INIS)

    The accumulation of impurities in local regions of PWR Steam Generators (SG) has resulted in the accelerated corrosion of SG materials. The chemical conditions in crevices and sludge piles is dependent on thermal hydraulic and mass transfer processes as well as the physical chemistry of the concentrated solution itself. This paper discusses the different modelling approaches which can be used to describe the concentration process and the local chemistry in these regions. The limitations of each approach and the applicability of model results to field conditions are discussed in the paper. EPRI's program in this area, including past accomplishments and the models used in the MULTEQ code are described in the paper. (author)

  9. Imitative modeling automatic system Control of steam pressure in the main steam collector with the influence on the main Servomotor steam turbine

    Science.gov (United States)

    Andriushin, A. V.; Zverkov, V. P.; Kuzishchin, V. F.; Ryzhkov, O. S.; Sabanin, V. R.

    2017-11-01

    The research and setting results of steam pressure in the main steam collector “Do itself” automatic control system (ACS) with high-speed feedback on steam pressure in the turbine regulating stage are presented. The ACS setup is performed on the simulation model of the controlled object developed for this purpose with load-dependent static and dynamic characteristics and a non-linear control algorithm with pulse control of the turbine main servomotor. A method for tuning nonlinear ACS with a numerical algorithm for multiparametric optimization and a procedure for separate dynamic adjustment of control devices in a two-loop ACS are proposed and implemented. It is shown that the nonlinear ACS adjusted with the proposed method with the regulators constant parameters ensures reliable and high-quality operation without the occurrence of oscillations in the transient processes the operating range of the turbine loads.

  10. Modelling of steam condensation in the primary flow channel of a gas-heated steam generator

    International Nuclear Information System (INIS)

    Kawamura, H.; Meister, G.

    1982-10-01

    A new simulation code has been developed for the analysis of steam ingress accidents in high temperatures reactors which evaluates the heat transfer in a steam generator headed by a mixture of helium and water steam. Special emphasis is laid on the analysis of steam condensation in the primary circuit of the steam generator. The code takes wall and bulk condensation into account. A new method is proposed to describe the entrainment of water droplets in the primary gas flow. Some typical results are given. Steam condensation in the primary channel may have a significant effect on temperature distributions. The effect on the heat transferred by the steam generator, however, is found to be not so prominent as might be expected. The reason is discussed. A simplified code will also be described, which gives results with reasonable accuracy within much shorter execution times. This code may be used as a program module in a program simulating the total primary circuit of a high temperature reactor. (orig.) [de

  11. Model predictive control for ethanol steam reformers with membrane separation

    OpenAIRE

    Serra, Maria; Ocampo-Martínez, Carlos; Li, Mingming; Llorca Piqué, Jordi

    2017-01-01

    © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This paper focuses on the dynamic modelling and the predictive control of an ethanol steam reformer (ESR) with Pdsingle bondAg membrane separation stage for the generation of pure hydrogen. Hydrogen purity necessary to feed a proton exchange membrane fuel cell (PEMFC) is required. A non-linear dynamic model of the ESR is developed together with a procedure f...

  12. Experimental characterization and modeling of an ethanol steam reformer

    DEFF Research Database (Denmark)

    Mandø, Matthias; Bovo, Mirko; Nielsen, Mads Pagh

    2006-01-01

    This work describes the characterization of an ethanol reforming system for a high temperature PEM fuel cell system. High temperature PEM fuel cells are well suited for operation on reformate gas due to the superior CO tolerance compared with low temperature PEM. Steam reforming of liquid biofuels...... (ethanol, bio-diesel etc.) represents sustainable sources of hydrogen for micro Combined Heat and Power (CHP) production as well as Auxiliary Power Units (APUs). The system was experimentally characterized and theoretically modelled using a 1-dimensional system model implemented in MATLAB...

  13. Modeling of Steam Distillation Mechanism during Steam Injection Process Using Artificial Intelligence

    OpenAIRE

    Daryasafar, Amin; Ahadi, Arash; Kharrat, Riyaz

    2014-01-01

    Steam distillation as one of the important mechanisms has a great role in oil recovery in thermal methods and so it is important to simulate this process experimentally and theoretically. In this work, the simulation of steam distillation is performed on sixteen sets of crude oil data found in the literature. Artificial intelligence (AI) tools such as artificial neural network (ANN) and also adaptive neurofuzzy interference system (ANFIS) are used in this study as effective methods to simulat...

  14. Preparatory studies for modelling steam condensation on soluble aerosols

    International Nuclear Information System (INIS)

    Dunbar, I.H.

    1988-01-01

    Of the fission products which would be released from the core of an LWR in the event of a severe accident, only the noble gases and possibly some of the iodine (depending on chemical form) are likely not to be in the form of aerosols when they reach the containment building atmosphere. Therefore in order to predict the extent of fission product retention on containment building internal structures, one needs to have a good understanding of aerosol deposition processes and of the factors which affect them. Following a severe accident in an LWR, a major component of the containment atmosphere will be steam. If the thermodynamic conditions allow condensation of this steam, this condensation is most likely to occur on the aerosol particles. A major component of the aerosol formed during the in-vessel release following a severe reactor accident will be fission product caesium. It is believed that much of this will enter the containment in the form of the hydroxide which has a great affinity for water, so particle growth due to steam condensation is likely to be a very important mechanism for retaining radioactive caesium within the containment builing. The author provides a systematic review of the basic chemical and physical issues which must be addressed if the phenomena are to be modelled accurately, and gives recommendations on how computer models of condensation onto soluble aerosols should be constructed. He proposes also to perform a systematic review of the existing literature and to perform small-scale thermodynamic experiments wherever important gaps in the data base are discovered

  15. Sterile Particles from the Flavor Gauge Model of Masses

    Czech Academy of Sciences Publication Activity Database

    Smetana, Adam

    2013-01-01

    Roč. 2013, č. 4 (2013), s. 139 ISSN 1029-8479 R&D Projects: GA MŠk LA08015 Institutional support: RVO:61389005 Keywords : dynamical mass generation * flavor gauge symmetry * right-handed neutrino condensation * sterile neutrinos * majorons Subject RIV: BE - Theoretical Physics Impact factor: 6.220, year: 2013

  16. Modelling the effects of the sterile insect technique applied to Eldana saccharina Walker in sugarcane

    Directory of Open Access Journals (Sweden)

    L Potgieter

    2012-12-01

    Full Text Available A mathematical model is formulated for the population dynamics of an Eldana saccharina Walker infestation of sugarcane under the influence of partially sterile released insects. The model describes the population growth of and interaction between normal and sterile E.saccharina moths in a temporally variable, but spatially homogeneous environment. The model consists of a deterministic system of difference equations subject to strictly positive initial data. The primary objective of this model is to determine suitable parameters in terms of which the above population growth and interaction may be quantified and according to which E.saccharina infestation levels and the associated sugarcane damage may be measured. Although many models have been formulated in the past describing the sterile insect technique, few of these models describe the technique for Lepidopteran species with more than one life stage and where F1-sterility is relevant. In addition, none of these models consider the technique when fully sterile females and partially sterile males are being released. The model formulated is also the first to describe the technique applied specifically to E.saccharina, and to consider the economic viability of applying the technique to this species. Pertinent decision support is provided to farm managers in terms of the best timing for releases, release ratios and release frequencies.

  17. Condensation of steam in horizontal pipes: model development and validation

    International Nuclear Information System (INIS)

    Szijarto, R.

    2015-01-01

    This thesis submitted to the Swiss Federal Institute of Technology ETH in Zurich presents the development and validation of a model for the condensation of steam in horizontal pipes. Condensation models were introduced and developed particularly for the application in the emergency cooling system of a Gen-III+ boiling water reactor. Such an emergency cooling system consists of slightly inclined horizontal pipes, which are immersed in a cold water tank. The pipes are connected to the reactor pressure vessel. They are responsible for a fast depressurization of the reactor core in the case of accident. Condensation in horizontal pipes was investigated with both one-dimensional system codes (RELAP5) and three-dimensional computational fluid dynamics software (ANSYS FLUENT). The performance of the RELAP5 code was not sufficient for transient condensation processes. Therefore, a mechanistic model was developed and implemented. Four models were tested on the LAOKOON facility, which analysed direct contact condensation in a horizontal duct

  18. Mathematical modeling of control system for the experimental steam generator

    Directory of Open Access Journals (Sweden)

    Podlasek Szymon

    2016-01-01

    Full Text Available A steam generator is an essential unit of each cogeneration system using steam machines. Currently one of the cheapest ways of the steam generation can be application of old steam generators came from army surplus store. They have relatively simple construction and in case of not so exploited units – quite good general conditions, and functionality of mechanical components. By contrast, electrical components and control systems (mostly based on relay automatics are definitely obsolete. It is not possible to use such units with cooperation of steam bus or with steam engines. In particular, there is no possibility for automatically adjustment of the pressure and the temperature of the generated steam supplying steam engines. Such adjustment is necessary in case of variation of a generator load. The paper is devoted to description of improvement of an exemplary unit together with construction of the measurement-control system based on a PLC. The aim was to enable for communication between the steam generator and controllers of the steam bus and steam engines in order to construction of a complete, fully autonomic and maintenance-free microcogeneration system.

  19. Modeling and simulation of a steam jaketed kettle using FIS

    International Nuclear Information System (INIS)

    Palijo, T. S.; Bhatti, I.

    2006-01-01

    Steam Jacketed Kettles are widely used in the CPI (Chemical Process Industries) for the reaction or processing purposes. The control of the temperature is related to control the rate of reaction. It is more complex to control the all parameters manually, so the controllers are required to design and operate the processes. In order to investigate theoretically the control of a process, it is necessary first to know the dynamic characteristics of the process, which is being controlled. In this paper we first analyze this complex system and its mathematical model. And then we have simulated the dynamics of this system using fuzzy logic approach. In this application Fuzzy logic based process controller has been designed for the steam-Jacketed kettle. Principal design elements used for the process controller are knowledge base, rule base, decision making logic and inference mechanism. The controller uses Fuzzy reasoning that in-fact is an inference system that derives conclusion from a set of Fuzzy IF...THEN rules, as well as known facts about the system. Simulation results obtained using FIS (Fuzzy Inference System) show that fuzzy logic based controller provided improved control of this dynamic process control system. (author)

  20. Rugged Ozone Sterilization System Model M1 (ROSS M1)

    Science.gov (United States)

    2017-07-13

    sterilization technologies on the market . Design verification and validation testing requirements were established through investigation of the predicate...evaluation of their capability as part of a larger system, the process was controlled through manual operation of valves, pumps, and controls. Figure 1...to control the process without a manual interface. The initial software iterations were written as a computer interface which would connect to the

  1. Prognostics for Steam Generator Tube Rupture using Markov Chain model

    International Nuclear Information System (INIS)

    Kim, Gibeom; Heo, Gyunyoung; Kim, Hyeonmin

    2016-01-01

    This paper will describe the prognostics method for evaluating and forecasting the ageing effect and demonstrate the procedure of prognostics for the Steam Generator Tube Rupture (SGTR) accident. Authors will propose the data-driven method so called MCMC (Markov Chain Monte Carlo) which is preferred to the physical-model method in terms of flexibility and availability. Degradation data is represented as growth of burst probability over time. Markov chain model is performed based on transition probability of state. And the state must be discrete variable. Therefore, burst probability that is continuous variable have to be changed into discrete variable to apply Markov chain model to the degradation data. The Markov chain model which is one of prognostics methods was described and the pilot demonstration for a SGTR accident was performed as a case study. The Markov chain model is strong since it is possible to be performed without physical models as long as enough data are available. However, in the case of the discrete Markov chain used in this study, there must be loss of information while the given data is discretized and assigned to the finite number of states. In this process, original information might not be reflected on prediction sufficiently. This should be noted as the limitation of discrete models. Now we will be studying on other prognostics methods such as GPM (General Path Model) which is also data-driven method as well as the particle filer which belongs to physical-model method and conducting comparison analysis

  2. Hydraulic model and steam flow numerical simulation of the Cerro Prieto geothermal field, Mexico, pipeline network

    International Nuclear Information System (INIS)

    García-Gutiérrez, A.; Hernández, A.F.; Martínez, J.I.; Ceceñas, M.; Ovando, R.; Canchola, I.

    2015-01-01

    The development of a hydraulic model and numerical simulation results of the Cerro Prieto geothermal field (CPGF) steam pipeline network are presented. Cerro Prieto is the largest water-dominant geothermal field in the world and its transportation network has 162 producing wells, connected through a network of pipelines that feeds 13 power-generating plants with an installed capacity of 720 MWe. The network is about 125 km long and has parallel high- and low-pressure networks. Prior to this study, it was suspected that steam flow stagnated or reversed from its planned direction in some segments of the network. Yet, the network complexity and extension complicated the analysis of steam transport for adequate delivery to the power plants. Thus, a hydraulic model of the steam transportation system was developed and implemented numerically using an existing simulator, which allowed the overall analysis of the network in order to quantify the pressure and energy losses as well as the steam flow direction in every part of the network. Numerical results of the high-pressure network were obtained which show that the mean relative differences between measured and simulated pressures and flowrates are less than 10%, which is considered satisfactory. Analysis of results led to the detection of areas of opportunity and to the recommendation of changes for improving steam transport. A main contribution of the present work is having simulated satisfactorily the longest (to our knowledge), and probably the most complex, steam pipeline network in the world. - Highlights: • Extensive literature review of flow models of geothermal steam gathering networks. • Hydraulic model of the Cerro Prieto geothermal field steam network. • Selection and validation of the employed pressure-drop model. • Numerical flow simulation of the world's largest geothermal steam gathering network. • Detailed network pressure drop analysis and mapping of steam flow distribution

  3. Exergetic Modelling of Oil-Fired Steam Boilers | Ohijeagbon ...

    African Journals Online (AJOL)

    The performance variables and potential for energy savings in oil-fired industrial steam boilers were studied. Operational parameters of steam boilers using low pour fuel oil (LPFO) and diesel were used to determine thermodynamic properties of material streams and exergetic parameters. Analysis of thermodynamic ...

  4. Steam Reforming of Bio-oil Model Compounds

    DEFF Research Database (Denmark)

    Trane, Rasmus; Jensen, Anker Degn; Dahl, Søren

    The steam reforming of bio-oil is a sustainable and renewable route to synthesis gas and hydrogen, where one of the main hurdles is carbon formation on the catalyst.......The steam reforming of bio-oil is a sustainable and renewable route to synthesis gas and hydrogen, where one of the main hurdles is carbon formation on the catalyst....

  5. The Wheel Model of STEAM Education Based on Traditional Korean Scientific Contents

    Science.gov (United States)

    Kim, Pyoung Won

    2016-01-01

    The Korean STEAM education pursues a convergent human resources education, but there are shortcomings associated with it due to the fact that it excludes the Humanities in its curriculum. This study embodies the accomplishments from the design and field application of the STEAM education model that has added Humanities fields (history, geography,…

  6. Computer model for predicting the effect of inherited sterility on population growth

    International Nuclear Information System (INIS)

    Carpenter, J.E.; Layton, R.C.

    1993-01-01

    A Fortran based computer program was developed to facilitate modelling different inherited sterility data sets under various paradigms. The model was designed to allow variable input for several different parameters, such as rate of increase per generation, release ratio and initial population levels, reproductive rates and sex ratios resulting from different matings, and the number of nights a female is active in mating and oviposition. The model and computer program should be valuable tools for recognizing areas in which information is lacking and for identifying the effect that different parameters can have on the efficacy of the inherited sterility method. (author). 8 refs, 4 figs

  7. Application of modeling to local chemistry in PWR steam generators

    International Nuclear Information System (INIS)

    Fauchon, C.; Millett, P.J.; Ollar, P.

    1998-01-01

    Localized corrosion of the SG tubes and other components is due to the presence of an aggressive environment in local crevices and occluded regions. In crevices and on vertical and horizontal tube surfaces, corrosion products and particulate matter can accumulate in the form of porous deposits. The SG water contains impurities at extremely low levels (ppb). Low levels of non-volatile impurities, however, can be efficiently concentrated in crevices and sludge piles by a thermal hydraulic mechanism. The temperature gradient across the SG tube coupled with local flow starvation, produces local boiling in the sludge and crevices. Since mass transfer processes are inhibited in these geometries, the residual liquid becomes enriched in many of the species present in the SG water. The resulting concentrated solutions have been shown to be aggressive and can corrode the SG materials. This corrosion may occur under various conditions which result in different types of attack such as pitting, stress corrosion cracking, wastage and denting. A major goal of EPRI's research program has been the development of models of the concentration process and the resulting chemistry. An improved understanding should eventually allow utilities to reduce or eliminate the corrosion by the appropriate manipulation of the steam generator water chemistry and or crevice conditions. The application of these models to experimental data obtained for prototypical SG tube support crevices is described in this paper. The models adequately describe the key features of the experimental data allowing extrapolations to be made to plant conditions. (author)

  8. Development and validation of a CFD-based steam reformer model

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen; Dahlqvist, Mathis; Saksager, Anders

    2006-01-01

    a detailed mechanism for the reforming reactions. Heat exchange between the flue gas and reformate streams through the reformer reactor walls was also included as a conjugate heat transfer process.  From a review of published models for the catalytic steam reforming of ethanol and preliminary predictions...... in a commercial ethanol steam reformer. The illustrations below show the measurements locations and predicted and measured temperature profiles. From detailed comparison with the measurements it was concluded that a mechanism for catalytic steam reforming of methane gives a reasonably accurate representation......Steam reforming of liquid biofuels (ethanol, bio-diesel etc.) represents a sustainable source of hydrogen for micro Combined Heat and Power (CHP) production as well as Auxiliary Power Units (APUs). In relation to the design of the steam reforming reactor several parameter are important including...

  9. MODELING AND SIMULATION PROCESS OF EXTRACTION ESSENTIAL OILS BY STEAM DISTILLATION

    OpenAIRE

    Armijo C., J.; Departamento Académico de Operaciones Unitarias, FQIQ, Universidad Nacional Mayor de San Marcos Lima, Perú; Vicuña G., E.; Departamento Académico de Análisis y Diseño de P., FQIQ, Universidad Nacional Mayor de San Marcos Lima, Perú; Romero y Otiniano, P.; Departamento Académico de Análisis y Diseño de P., FQIQ, Universidad Nacional Mayor de San Marcos Lima, Perú; Condorhuamán C., C.; Departamento Académico de Operaciones Unitarias, FQIQ, Universidad Nacional Mayor de San Marcos Lima, Perú; Hilario R., B.; Departamento Académico de Química Inorgánica, FQIQ, Universidad Nacional Mayor de San Marcos Lima, Perú

    2014-01-01

    This paper presents an investigation of the extraction of essential oils by steam distillation. The process is analyzed and a model is developed for the extraction of essential oil of eucalyptus in pilot scale with a steam flow of 5.73 g / min. According to the model Dunckhorst-Houghton, which considers the effect of axial dispersion, and the use of optimization procedures to establish the model parameters, excellent agreement was obtained between the amount of oil extracted theoretical and e...

  10. The Effect of Sterilization on Size and Shape of Fat Globules in Model Processed Cheese Samples

    Directory of Open Access Journals (Sweden)

    B. Tremlová

    2006-01-01

    Full Text Available Model cheese samples from 4 independent productions were heat sterilized (117 °C, 20 minutes after the melting process and packing with an aim to prolong their durability. The objective of the study was to assess changes in the size and shape of fat globules due to heat sterilization by using image analysis methods. The study included a selection of suitable methods of preparation mounts, taking microphotographs and making overlays for automatic processing of photographs by image analyser, ascertaining parameters to determine the size and shape of fat globules and statistical analysis of results obtained. The results of the experiment suggest that changes in shape of fat globules due to heat sterilization are not unequivocal. We found that the size of fat globules was significantly increased (p < 0.01 due to heat sterilization (117 °C, 20 min, and the shares of small fat globules (up to 500 μm2, or 100 μm2 in the samples of heat sterilized processed cheese were decreased. The results imply that the image analysis method is very useful when assessing the effect of technological process on the quality of processed cheese quality.

  11. Modeling a Helical-coil Steam Generator in RELAP5-3D for the Next Generation Nuclear Plant

    Energy Technology Data Exchange (ETDEWEB)

    Nathan V. Hoffer; Piyush Sabharwall; Nolan A. Anderson

    2011-01-01

    Options for the primary heat transport loop heat exchangers for the Next Generation Nuclear Plant are currently being evaluated. A helical-coil steam generator is one heat exchanger design under consideration. Safety is an integral part of the helical-coil steam generator evaluation. Transient analysis plays a key role in evaluation of the steam generators safety. Using RELAP5-3D to model the helical-coil steam generator, a loss of pressure in the primary side of the steam generator is simulated. This report details the development of the steam generator model, the loss of pressure transient, and the response of the steam generator primary and secondary systems to the loss of primary pressure. Back ground on High Temperature Gas-cooled reactors, steam generators, the Next Generation Nuclear Plant is provided to increase the readers understanding of the material presented.

  12. Modeling of soluble impurities distribution in the steam generator secondary water

    International Nuclear Information System (INIS)

    Matal, O.; Simo, T.; Kucak, L.; Urban, F.

    1997-01-01

    A model was developed to compute concentration of impurities in the WWER 440 steam generator (SG) secondary water along the tube bundle. Calculated values were verified by concentration values obtained from secondary water sample chemical analysis. (orig.)

  13. Modeling of soluble impurities distribution in the steam generator secondary water

    Energy Technology Data Exchange (ETDEWEB)

    Matal, O.; Simo, T. [Energovyzkum s.r.o., Brno (Switzerland); Kucak, L.; Urban, F. [Slovak Technical Univ., Bratislava (Slovakia)

    1997-12-31

    A model was developed to compute concentration of impurities in the WWER 440 steam generator (SG) secondary water along the tube bundle. Calculated values were verified by concentration values obtained from secondary water sample chemical analysis. (orig.). 2 refs.

  14. Calculation model for 16N transit time in the secondary side of steam generators

    International Nuclear Information System (INIS)

    Liu Songyu; Xu Jijun; Xu Ming

    1998-01-01

    The 16 N transit time is essential to determine the leak-rate of steam generator tubes leaks with 16 N monitoring system, which is a new technique. A model was developed for calculation 16 N transit time in the secondary side of steam generators. According to the flow characters of secondary side fluid, the transit times divide into four sectors from tube sheet to the sensor on steam line. The model assumes that 16 N is moving as vapor phase in the secondary-side. So the model for vapor velocity distribution in tube bundle is presented in detail. The 16 N transit time calculation results of this model compare with these of EDF on steam generator of Qinshan NPP

  15. Parametric model to estimate containment loads following an ex-vessel steam spike

    International Nuclear Information System (INIS)

    Lopez, R.; Hernandez, J.; Huerta, A.

    1998-01-01

    This paper describes the use of a relatively simple parametric model to estimate containment loads following an ex-vessel steam spike. The study was motivated because several PSAs have identified containment loads accompanying reactor vessel failures as a major contributor to early containment failure. The paper includes a detailed description of the simple but physically sound parametric model which was adopted to estimate containment loads following a steam spike into the reactor cavity. (author)

  16. Two-dimensional modeling of water spray cooling in superheated steam

    Directory of Open Access Journals (Sweden)

    Ebrahimian Vahid

    2008-01-01

    Full Text Available Spray cooling of the superheated steam occurs with the interaction of many complex physical processes, such as initial droplet formation, collision, coalescence, secondary break up, evaporation, turbulence generation, and modulation, as well as turbulent mixing, heat, mass and momentum transfer in a highly non-uniform two-phase environment. While it is extremely difficult to systematically study particular effects in this complex interaction in a well defined physical experiment, the interaction is well suited for numerical studies based on advanced detailed models of all the processes involved. This paper presents results of such a numerical experiment. Cooling of the superheated steam can be applied in order to decrease the temperature of superheated steam in power plants. By spraying the cooling water into the superheated steam, the temperature of the superheated steam can be controlled. In this work, water spray cooling was modeled to investigate the influences of the droplet size, injected velocity, the pressure and velocity of the superheated steam on the evaporation of the cooling water. The results show that by increasing the diameter of the droplets, the pressure and velocity of the superheated steam, the amount of evaporation of cooling water increases. .

  17. Evaluation of the Sensitivity of Two-Phase Flow Model for the Steam Separator Analysis

    International Nuclear Information System (INIS)

    Michio Murase; Masao Chaki

    2006-01-01

    Reducing of the pressure losses of steam separator systems of boiling water reactor (BWR) plants is useful to reduce the required pump head and enhance core stability design margin. The need to reduce the pressure losses of steam separator systems is especially important in BWR plants that have high power density cores and natural circulation systems. The core flow rate of a BWR plant with a natural circulation system is affected by the pressure losses of steam separator systems. In BWR plants with high power density cores, the core stability design margin is affected by these pressure losses. Generally, reducing the pressure losses of the steam separator systems leads to increased carry-under and carryover. Reducing the pressure losses while keeping the characteristics of both carry-under and carryover is desired, so many studies have been done. The steam separator of a BWR plant consists of a standpipe section, a swirl vane section and three-barrel sections. Two-phase flow of steam and water enters the steam separator through the standpipe section and reaches the swirl vane section. In the swirl vane section, the two-phase flow is given centrifugal force and is basically separated into steam and water. Therefore investigating the two-phase flow characteristics of the swirl vane section is very important. After the swirl vane section, the two-phase flow enters the barrel sections. Each barrel has a pick-off ring. The water in the barrel section is mainly removed by these pick-off rings because the water mainly flows upward as a liquid film in the barrel section due to the centrifugal force given in the swirl vane section. We researched the effect of using the drag force model of the swirling two-phase flow in analyzing a steam separator and we found that the drag force model greatly affects the results of the analysis. (authors)

  18. SOX - Towards the detection of sterile neutrinos in Borexino. Beta spectrum modeling, Monte Carlo development and sensitivity studies for the sterile neutrino search in Borexino

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Mikko

    2016-12-15

    Several experiments have reported anomalies in the neutrino sector which might be explained by the existence of a fourth (sterile) neutrino with a squared mass difference of about 1 eV{sup 2} to the other three active neutrinos. The SOX project is part of the experimental program of the Borexino experiment and seeks for a clarification of the observed anomalies. For that purpose an artificial antineutrino source ({sup 144}Ce-{sup 144}Pr) and possibly neutrino source ({sup 51}Cr) will be deployed underneath the large low background detector Borexino. The detector provides both energy and vertex resolution to observe a possible oscillation signature within the detector volume. The calculation of the antineutrino spectrum is based on existing theoretical models and was performed within this thesis. The modeling includes several sub-leading corrections particularly such as finite size of the nucleus, screening of the atomic electrons and radiative effects. Related to this work, dedicated Monte Carlo generators have been developed to simulate the inverse beta decay reaction and the (anti)neutrino elastic scattering off electrons. Based on a profile likelihood analysis, the sensitivity to the sterile neutrino search of the SOX project was evaluated. The results obtained from this analysis confirm that the currently allowed parameter regions for sterile neutrinos can be tested at 95% confidence level. Finally, an alternative concept for the sterile neutrino search is presented which is based on a cyclotron and a Beryllium target near Borexino (Borexino+IsoDAR).

  19. SOX - Towards the detection of sterile neutrinos in Borexino. Beta spectrum modeling, Monte Carlo development and sensitivity studies for the sterile neutrino search in Borexino

    International Nuclear Information System (INIS)

    Meyer, Mikko

    2016-12-01

    Several experiments have reported anomalies in the neutrino sector which might be explained by the existence of a fourth (sterile) neutrino with a squared mass difference of about 1 eV 2 to the other three active neutrinos. The SOX project is part of the experimental program of the Borexino experiment and seeks for a clarification of the observed anomalies. For that purpose an artificial antineutrino source ( 144 Ce- 144 Pr) and possibly neutrino source ( 51 Cr) will be deployed underneath the large low background detector Borexino. The detector provides both energy and vertex resolution to observe a possible oscillation signature within the detector volume. The calculation of the antineutrino spectrum is based on existing theoretical models and was performed within this thesis. The modeling includes several sub-leading corrections particularly such as finite size of the nucleus, screening of the atomic electrons and radiative effects. Related to this work, dedicated Monte Carlo generators have been developed to simulate the inverse beta decay reaction and the (anti)neutrino elastic scattering off electrons. Based on a profile likelihood analysis, the sensitivity to the sterile neutrino search of the SOX project was evaluated. The results obtained from this analysis confirm that the currently allowed parameter regions for sterile neutrinos can be tested at 95% confidence level. Finally, an alternative concept for the sterile neutrino search is presented which is based on a cyclotron and a Beryllium target near Borexino (Borexino+IsoDAR).

  20. Sterilization by gamma irradiation

    International Nuclear Information System (INIS)

    Reyes Frias, L.

    1992-01-01

    Since 1980 the National Institute of Nuclear Research counts with an Industrial Gamma Irradiator, for the sterilization of raw materials and finished products. Through several means has been promoted the use of this technology as alternative to conventional methods of sterilization as well as steam treatment and ethylene oxide. As a result of the made promotion this irradiator has come to its saturation limit being the sterilization irradiation one of the main services that National Institute of Nuclear Research offers to producer enterprises of disposable materials of medical use also of raw materials for the elaboration of cosmetic products and pharmaceuticals as well as dehydrated foods. It is presented the trend to the sterilization service by irradiation showed by the compilation data in a survey made by potential customers. (Author)

  1. Preparatory selection of sterilization regime for canned Natural Atlantic Mackerel with oil based on developed mathematical models of the process

    Directory of Open Access Journals (Sweden)

    Maslov A. A.

    2016-12-01

    Full Text Available Definition of preparatory parameters for sterilization regime of canned "Natural Atlantic Mackerel with Oil" is the aim of current study. PRSC software developed at the department of automation and computer engineering is used for preparatory selection. To determine the parameters of process model, in laboratory autoclave AVK-30M the pre-trial process of sterilization and cooling in water with backpressure of canned "Natural Atlantic Mackerel with Oil" in can N 3 has been performed. Gathering information about the temperature in the autoclave sterilization chamber and the can with product has been carried out using Ellab TrackSense PRO loggers. Due to the obtained information three transfer functions for the product model have been identified: in the least heated area of autoclave, the average heated and the most heated. In PRSC programme temporary temperature dependences in the sterilization chamber have been built using this information. The model of sterilization process of canned "Natural Atlantic Mackerel with Oil" has been received after the pre-trial process. Then in the automatic mode the sterilization regime of canned "Natural Atlantic Mackerel with Oil" has been selected using the value of actual effect close to normative sterilizing effect (5.9 conditional minutes. Furthermore, in this study step-mode sterilization of canned "Natural Atlantic Mackerel with Oil" has been selected. Utilization of step-mode sterilization with the maximum temperature equal to 125 °C in the sterilization chamber allows reduce process duration by 10 %. However, the application of this regime in practice requires additional research. Using the described approach based on the developed mathematical models of the process allows receive optimal step and variable canned food sterilization regimes with high energy efficiency and product quality.

  2. Modeling of an once through helical coil steam generator of a superheated cycle for sizing analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeon Sik; Sim, Yoon Sub; Kim, Eui Kwang [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1997-12-31

    A thermal sizing code, named as HSGSA (Helical coil Steam Generator Sizing Analyzer), for a sodium heated helical coil steam generator is developed for KALIMER (Korea Advanced LIquid MEtal Reactor) design. The theoretical modeling of the shell and tube sides is described and relevant correlations are presented. For assessment of HSGSA, a reference plant design case is compared to the calculational outputs from HSGSA simulation. 9 refs., 6 figs. (Author)

  3. A theoretical model of air and steam co-injection to prevent the downward migration of DNAPLs during steam-enhanced extraction

    Science.gov (United States)

    Kaslusky, Scott F.; Udell, Kent S.

    2002-04-01

    When steam is injected into soil containing a dense volatile non-aqueous phase liquid contaminant the DNAPL vaporized within the heated soil region condenses and accumulates ahead of the steam condensation front. If enough DNAPL accumulates, gravitational forces can overcome trapping forces allowing the liquid contaminant to flow downward. By injecting air with steam, a portion of the DNAPL vapor remains suspended in equilibrium with the air, decreasing liquid contaminant accumulation ahead of the steam condensation front, and thus reducing the possibility of downward migration. In this work, a one-dimensional theoretical model is developed to predict the injection ratio of air to steam that will prevent the accumulation of volatile DNAPLs. The contaminated region is modeled as a one-dimensional homogeneous porous medium with an initially uniform distribution of a single component contaminant. Mass and energy balances are combined to determine the injection ratio of air to steam that eliminates accumulation of the contaminant ahead of the steam condensation front, and hence reduces the possibility of downward migration. The minimum injection ratio that eliminates accumulation is defined as the optimum injection ratio. Example calculations are presented for three DNAPLs, carbon tetrachloride (CCl 4), trichloroethylene (TCE), and perchloroethylene (PCE). The optimum injection ratio of air to steam is shown to depend on the initial saturation and the volatility of the liquid contaminant. Numerical simulation results are presented to validate the model, and to illustrate downward migration for ratios less than optimum. Optimum injection ratios determined from numerical simulations are shown to be in good agreement with the theoretical model.

  4. Effect of two viscosity models on lethality estimation in sterilization of liquid canned foods.

    Science.gov (United States)

    Calderón-Alvarado, M P; Alvarado-Orozco, J M; Herrera-Hernández, E C; Martínez-González, G M; Miranda-López, R; Jiménez-Islas, H

    2016-09-01

    A numerical study on 2D natural convection in cylindrical cavities during the sterilization of liquid foods was performed. The mathematical model was established on momentum and energy balances and predicts both the heating dynamics of the slowest heating zone (SHZ) and the lethal rate achieved in homogeneous liquid canned foods. Two sophistication levels were proposed in viscosity modelling: 1) considering average viscosity and 2) using an Arrhenius-type model to include the effect of temperature on viscosity. The remaining thermodynamic properties were kept constant. The governing equations were spatially discretized via orthogonal collocation (OC) with mesh size of 25 × 25. Computational simulations were performed using proximate and thermodynamic data for carrot-orange soup, broccoli-cheddar soup, tomato puree, and cream-style corn. Flow patterns, isothermals, heating dynamics of the SHZ, and the sterilization rate achieved for the cases studied were compared for both viscosity models. The dynamics of coldest point and the lethal rate F0 in all food fluids studied were approximately equal in both cases, although the second sophistication level is closer to physical behavior. The model accuracy was compared favorably with reported sterilization time for cream-style corn packed at 303 × 406 can size, predicting 66 min versus an experimental time of 68 min at retort temperature of 121.1 ℃. © The Author(s) 2016.

  5. Gasification under CO2–Steam Mixture: Kinetic Model Study Based on Shared Active Sites

    Directory of Open Access Journals (Sweden)

    Xia Liu

    2017-11-01

    Full Text Available In this work, char gasification of two coals (i.e., Shenfu bituminous coal and Zunyi anthracite and a petroleum coke under a steam and CO2 mixture (steam/CO2 partial pressures, 0.025–0.075 MPa; total pressures, 0.100 MPa and CO2/steam chemisorption of char samples were conducted in a Thermogravimetric Analyzer (TGA. Two conventional kinetic models exhibited difficulties in exactly fitting the experimental data of char–steam–CO2 gasification. Hence, a modified model based on Langmuir–Hinshelwood model and assuming that char–CO2 and char–steam reactions partially shared active sites was proposed and had indicated high accuracy for estimating the interactions in char–steam–CO2 reaction. Moreover, it was found that two new model parameters (respectively characterized as the amount ratio of shared active sites to total active sites in char–CO2 and char–steam reactions in the modified model hardly varied with gasification conditions, and the results of chemisorption indicate that these two new model parameters mainly depended on the carbon active sites in char samples.

  6. Dynamic modeling and simulation of EBR-II steam generator system

    International Nuclear Information System (INIS)

    Berkan, R.C.; Upadhyaya, B.R.

    1989-01-01

    This paper presents a low order dynamic model of the Experimental breeder Reactor-II (EBR-II) steam generator system. The model development includes the application of energy, mass and momentum balance equations in state-space form. The model also includes a three-element controller for the drum water level control problem. The simulation results for low-level perturbations exhibit the inherently stable characteristics of the steam generator. The predictions of test transients also verify the consistency of this low order model

  7. Linear parameter-varying modeling and control of the steam temperature in a Canadian SCWR

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Peiwei, E-mail: sunpeiwei@mail.xjtu.edu.cn; Zhang, Jianmin; Su, Guanghui

    2017-03-15

    Highlights: • Nonlinearity of Canadian SCWR is analyzed based on step responses and Nyquist plots. • LPV model is derived through Jacobian linearization and curve fitting. • An output feedback H{sub ∞} controller is synthesized for the steam temperature. • The control performance is evaluated by step disturbances and wide range operation. • The controller can stabilize the system and reject the reactor power disturbance. - Abstract: The Canadian direct-cycle Supercritical Water-cooled Reactor (SCWR) is a pressure-tube type SCWR under development in Canada. The dynamics of the steam temperature have a high degree of nonlinearity and are highly sensitive to reactor power disturbances. Traditional gain scheduling control cannot theoretically guarantee stability for all operating regions. The control performance can also be deteriorated when the controllers are switched. In this paper, a linear parameter-varying (LPV) strategy is proposed to solve such problems. Jacobian linearization and curve fitting are applied to derive the LPV model, which is verified using a nonlinear dynamic model and determined to be sufficiently accurate for control studies. An output feedback H{sub ∞} controller is synthesized to stabilize the steam temperature system and reject reactor power disturbances. The LPV steam temperature controller is implemented using a nonlinear dynamic model, and step changes in the setpoints and typical load patterns are carried out in the testing process. It is demonstrated through numerical simulation that the LPV controller not only stabilizes the steam temperature under different disturbances but also efficiently rejects reactor power disturbances and suppresses the steam temperature variation at different power levels. The LPV approach is effective in solving control problems of the steam temperature in the Canadian SCWR.

  8. Linear parameter-varying modeling and control of the steam temperature in a Canadian SCWR

    International Nuclear Information System (INIS)

    Sun, Peiwei; Zhang, Jianmin; Su, Guanghui

    2017-01-01

    Highlights: • Nonlinearity of Canadian SCWR is analyzed based on step responses and Nyquist plots. • LPV model is derived through Jacobian linearization and curve fitting. • An output feedback H ∞ controller is synthesized for the steam temperature. • The control performance is evaluated by step disturbances and wide range operation. • The controller can stabilize the system and reject the reactor power disturbance. - Abstract: The Canadian direct-cycle Supercritical Water-cooled Reactor (SCWR) is a pressure-tube type SCWR under development in Canada. The dynamics of the steam temperature have a high degree of nonlinearity and are highly sensitive to reactor power disturbances. Traditional gain scheduling control cannot theoretically guarantee stability for all operating regions. The control performance can also be deteriorated when the controllers are switched. In this paper, a linear parameter-varying (LPV) strategy is proposed to solve such problems. Jacobian linearization and curve fitting are applied to derive the LPV model, which is verified using a nonlinear dynamic model and determined to be sufficiently accurate for control studies. An output feedback H ∞ controller is synthesized to stabilize the steam temperature system and reject reactor power disturbances. The LPV steam temperature controller is implemented using a nonlinear dynamic model, and step changes in the setpoints and typical load patterns are carried out in the testing process. It is demonstrated through numerical simulation that the LPV controller not only stabilizes the steam temperature under different disturbances but also efficiently rejects reactor power disturbances and suppresses the steam temperature variation at different power levels. The LPV approach is effective in solving control problems of the steam temperature in the Canadian SCWR.

  9. Spacecraft sterilization.

    Science.gov (United States)

    Kalfayan, S. H.

    1972-01-01

    Spacecraft sterilization is a vital factor in projects for the successful biological exploration of other planets. The microorganisms of major concern are the fungi and bacteria. Sterilization procedures are oriented toward the destruction of bacterial spores. Gaseous sterilants are examined, giving attention to formaldehyde, beta-propiolactone, ethylene oxide, and the chemistry of the bactericidal action of sterilants. Radiation has been seriously considered as another method for spacecraft sterilization. Dry heat sterilization is discussed together with the effects of ethylene oxide decontamination and dry heat sterilization on materials.

  10. Sterile neutrinos in cosmology

    Science.gov (United States)

    Abazajian, Kevork N.

    2017-11-01

    Sterile neutrinos are natural extensions to the standard model of particle physics in neutrino mass generation mechanisms. If they are relatively light, less than approximately 10 keV, they can alter cosmology significantly, from the early Universe to the matter and radiation energy density today. Here, we review the cosmological role such light sterile neutrinos can play from the early Universe, including production of keV-scale sterile neutrinos as dark matter candidates, and dynamics of light eV-scale sterile neutrinos during the weakly-coupled active neutrino era. We review proposed signatures of light sterile neutrinos in cosmic microwave background and large scale structure data. We also discuss keV-scale sterile neutrino dark matter decay signatures in X-ray observations, including recent candidate ∼3.5 keV X-ray line detections consistent with the decay of a ∼7 keV sterile neutrino dark matter particle.

  11. Modelling horizontal steam generator with ATHLET. Verification of different nodalization schemes and implementation of verified constitutive equations

    Energy Technology Data Exchange (ETDEWEB)

    Beliaev, J.; Trunov, N.; Tschekin, I. [OKB Gidropress (Russian Federation); Luther, W. [GRS Garching (Germany); Spolitak, S. [RNC-KI (Russian Federation)

    1995-12-31

    Currently the ATHLET code is widely applied for modelling of several Power Plants of WWER type with horizontal steam generators. A main drawback of all these applications is the insufficient verification of the models for the steam generator. This paper presents the nodalization schemes for the secondary side of the steam generator, the results of stationary calculations, and preliminary comparisons to experimental data. The consideration of circulation in the water inventory of the secondary side is proved to be necessary. (orig.). 3 refs.

  12. Exergy Analysis of a Subcritical Reheat Steam Power Plant with Regression Modeling and Optimization

    Directory of Open Access Journals (Sweden)

    MUHIB ALI RAJPER

    2016-07-01

    Full Text Available In this paper, exergy analysis of a 210 MW SPP (Steam Power Plant is performed. Firstly, the plant is modeled and validated, followed by a parametric study to show the effects of various operating parameters on the performance parameters. The net power output, energy efficiency, and exergy efficiency are taken as the performance parameters, while the condenser pressure, main steam pressure, bled steam pressures, main steam temperature, and reheat steam temperature isnominated as the operating parameters. Moreover, multiple polynomial regression models are developed to correlate each performance parameter with the operating parameters. The performance is then optimizedby using Direct-searchmethod. According to the results, the net power output, energy efficiency, and exergy efficiency are calculated as 186.5 MW, 31.37 and 30.41%, respectively under normal operating conditions as a base case. The condenser is a major contributor towards the energy loss, followed by the boiler, whereas the highest irreversibilities occur in the boiler and turbine. According to the parametric study, variation in the operating parameters greatly influences the performance parameters. The regression models have appeared to be a good estimator of the performance parameters. The optimum net power output, energy efficiency and exergy efficiency are obtained as 227.6 MW, 37.4 and 36.4, respectively, which have been calculated along with optimal values of selected operating parameters.

  13. A Steam Utility Network Model for the Evaluation of Heat Integration Retrofits – A Case Study of an Oil Refinery

    Directory of Open Access Journals (Sweden)

    Sofie Marton

    2017-12-01

    Full Text Available This paper presents a real industrial example in which the steam utility network of a refinery is modelled in order to evaluate potential Heat Integration retrofits proposed for the site. A refinery, typically, has flexibility to optimize the operating strategy for the steam system depending on the operation of the main processes. This paper presents a few examples of Heat Integration retrofit measures from a case study of a large oil refinery. In order to evaluate expected changes in fuel and electricity imports to the refinery after implementation of the proposed retrofits, a steam system model has been developed. The steam system model has been tested and validated with steady state data from three different operating scenarios and can be used to evaluate how changes to steam balances at different pressure levels would affect overall steam balances, generation of shaft power in turbines, and the consumption of fuel gas.

  14. Development and application of an entrainment model for the PWR U-tube steam generators for main steam line break analysis

    International Nuclear Information System (INIS)

    Song, Dong-Soo; Park, Young-Chan

    2004-01-01

    The purpose of this paper is to present the analyses that were performed to develop and use an entrainment model for pressurized water reactor U-tube steam generators (SG) for main steam line break (MSLB) analyses. The entrainment model was developed using the RETRAN-3D computer program, and the model was benchmarked against experimental data of moisture carryover during a simulated MSLB accident. The application methodology was also developed to incorporate into the MSLB mass and energy release calculations for Kori Unit 1. This methodology utilizes LOFTRAN and RETRAN-3D codes in an iterative sequence of cases in which the LOFTRAN nuclear steam supply system model provides boundary conditions for the RETRAN-3D broken loop steam generator model, and the RETRAN-3D model provides the entrainment data that is input back into the LOFTRAN model. FORTRAN programs were developed to facilitate the sequencing of these iterative calculations. As a result of applying the entrainment model to Kori Unit 1, the temperature calculated inside Containment during MSLB accident using the CONTEMP-LT computer program decreased by about 25degC. Consequently this entrainment model provides a significant benefit by decreasing the temperature envelop for environment qualification as well as decreasing the peak Containment pressure. (author)

  15. Internal steam reforming in solid oxide fuel cells: Status and opportunities of kinetic studies and their impact on modelling

    DEFF Research Database (Denmark)

    Mogensen, David; Grunwaldt, J.-D.; Hendriksen, Peter Vang

    2011-01-01

    of such a system require SOFC models that include accurate description of the steam reforming rate. The objective of this article is to review the reported kinetic expressions for the steam reforming reaction. Extensive work has been performed on traditional catalysts for steam reforming. Because of differences...... modeling, such expression are however lacking, but it may be viable to use measurements on industrial steam reforming catalysts instead. Nevertheless there is a further need for experimental studies on determining the exact steam reforming kinetics for SOFC anodes.......Solid oxide fuel cells (SOFC) systems with internal steam reforming have the potential to become an economically competitive technology for cogeneration power plants, exploiting its significantly higher electrical efficiency compared to existing technologies. Optimal design and operation...

  16. Seismic response analysis and test of CHASNUPP steam generator lower part model

    International Nuclear Information System (INIS)

    Han Liangbi; Xu Jinkang; Zhan Jingxian; He Yinbiao; Wang Peizhu

    1997-12-01

    The seismic response analysis and test of CHASNUPP steam generator lower part model has been performed. The lower part model consists of a tube sheet, 441 U-shaped rods (modeled on U-shaped tubes), 9 tie rods, a tube bundle wrapper, a lower shell and some position bolts between the lower shell and the wrapper. The analytical and experimental data show that the steam generator lower part model is more stiffer than pure tube bundle model. The movement of the lower part model appears in a systematic model in earthquake condition. The fundamental natural frequency of this model is higher than that of the tube bundle model and lower than that of the lower shell. The global frequency components are absolutely dominant and the local frequency components are insignificant. The experimental data are in good agreement with the results from finite element method. The effectiveness of mathematical model is verified

  17. Reversible Sterilization

    Science.gov (United States)

    Largey, Gale

    1977-01-01

    Notes that difficult questions arise concerning the use of sterilization for alleged eugenic and euthenic purposes. Thus, how reversible sterilization will be used with relation to the poor, mentally ill, mentally retarded, criminals, and minors, is questioned. (Author/AM)

  18. Sound speed models for a noncondensible gas-steam-water mixture

    International Nuclear Information System (INIS)

    Ransom, V.H.; Trapp, J.A.

    1984-01-01

    An analytical expression is derived for the homogeneous equilibrium speed of sound in a mixture of noncondensible gas, steam, and water. The expression is based on the Gibbs free energy interphase equilibrium condition for a Gibbs-Dalton mixture in contact with a pure liquid phase. Several simplified models are discussed including the homogeneous frozen model. These idealized models can be used as a reference for data comparison and also serve as a basis for empirically corrected nonhomogeneous and nonequilibrium models

  19. Performance of fluidized bed steam gasification of biomass - Modeling and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Loha, Chanchal; Chatterjee, Pradip K. [Thermal Engineering Group, Central Mechanical Engineering Research Institute, CSIR, Durgapur 713 209 (India); Chattopadhyay, Himadri [Dept. of Mechanical Engineering, Jadavpur University, Kolkata 700 032 (India)

    2011-03-15

    This paper presents the investigation of the performance from different biomasses in a fluidized bed gasifier where steam has been used as gasifying as well as fluidizing agent. An experimental setup is fabricated to study the gasification performance of rice husk, which is of special relevance to rice-producing countries like China and India. An equilibrium modeling approach is deployed to predict the gas composition which has been compared with the experimental results. Calibration of the model with appropriate modeling coefficients was necessary to achieve close resemblance with the experimental values. Further, the model is used to predict the gas compositions from other biomass and benchmarked with the performance of coal. In this study, the gasification temperature is varied from 650 C to 800 C, whereas the steam-to-biomass ratio (S/B) is varied from 0.75 to 2.00. As the gasification temperature increases, the production of H{sub 2} and CO increases but the generation of CH{sub 4} and CO{sub 2} reduces. The steam-to-biomass ratio was again found to influence the production rates. With increasing steam input, H{sub 2}, CO{sub 2} and CH{sub 4} were found to increase while CO reduces. (author)

  20. Sustainable hydrogen from bio-oil - Catalytic steam reforming of acetic acid as a model oxygenate

    NARCIS (Netherlands)

    Takanabe, Kazuhiro; Seshan, K.; Lefferts, Leon; Aika, Ken-ichi

    2004-01-01

    Steam reforming of acetic acid as a model oxygenate present in bio-oil over Pt/ZrO2 catalysts has been studied. Pt/ZrO2 catalysts are very active, completely converting acetic acid and give hydrogen yield close to thermodynamic equilibrium. The catalyst deactivated by formation of oligomers, which

  1. Sustainable hydrogen from bio-oil - Catalytic steam reforming of acetic acid as a model oxygenate

    NARCIS (Netherlands)

    Takanabe, Kazuhiro; Aika, Ken-ichi; Seshan, K.; Lefferts, Leon

    Studies were conducted with acetic acid (HAc) as model oxygenate for the design of active and stable catalysts for steam reforming of bio-oil. Pt/ZrO2 catalysts were prepared by wet impregnation technique. The Pt/ZrO2 catalysts showed high activities at initial time on stream, but lost its activity

  2. A MATHEMATICAL MODEL OF THE ROASTING CHESTNUTS PROCESS BY SUPERHEATED STEAM

    Directory of Open Access Journals (Sweden)

    A. N. Ostrikov

    2013-01-01

    Full Text Available The mathematic modeling for chestnuts roasting process by superheated steam is conducted. Diffusion and thermal diffusion coefficients are used for process description. Initial conditions and boundary conditions of the third kind for thermal conductivity and mass transfer equations are set.

  3. Modeling and simulation of an isothermal reactor for methanol steam reforming

    Directory of Open Access Journals (Sweden)

    Raphael Menechini Neto

    2014-04-01

    Full Text Available Due to growing electricity demand, cheap renewable energy sources are needed. Fuel cells are an interesting alternative for generating electricity since they use hydrogen as their main fuel and release only water and heat to the environment. Although fuel cells show great flexibility in size and operating temperature (some models even operate at low temperatures, the technology has the drawback for hydrogen transportation and storage. However, hydrogen may be produced from methanol steam reforming obtained from renewable sources such as biomass. The use of methanol as raw material in hydrogen production process by steam reforming is highly interesting owing to the fact that alcohol has the best hydrogen carbon-1 ratio (4:1 and may be processed at low temperatures and atmospheric pressures. They are features which are desirable for its use in autonomous fuel cells. Current research develops a mathematical model of an isothermal methanol steam reforming reactor and validates it against experimental data from the literature. The mathematical model was solved numerically by MATLAB® and the comparison of its predictions for different experimental conditions indicated that the developed model and the methodology for its numerical solution were adequate. Further, a preliminary analysis was undertaken on methanol steam reforming reactor project for autonomous fuel cell.

  4. Control-volume-based model of the steam-water injector flow

    Science.gov (United States)

    Kwidziński, Roman

    2010-03-01

    The paper presents equations of a mathematical model to calculate flow parameters in characteristic cross-sections in the steam-water injector. In the model, component parts of the injector (steam nozzle, water nozzle, mixing chamber, condensation wave region, diffuser) are treated as a series of connected control volumes. At first, equations for the steam nozzle and water nozzle are written and solved for known flow parameters at the injector inlet. Next, the flow properties in two-phase flow comprising mixing chamber and condensation wave region are determined from mass, momentum and energy balance equations. Then, water compression in diffuser is taken into account to evaluate the flow parameters at the injector outlet. Irreversible losses due to friction, condensation and shock wave formation are taken into account for the flow in the steam nozzle. In two-phase flow domain, thermal and mechanical nonequilibrium between vapour and liquid is modelled. For diffuser, frictional pressure loss is considered. Comparison of the model predictions with experimental data shows good agreement, with an error not exceeding 15% for discharge (outlet) pressure and 1 K for outlet temperature.

  5. Development and validation of a CFD-based steam reformer model

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen; Dahlqvist, Mathis; Saksager, Anders

    2006-01-01

    a detailed mechanism for the reforming reactions. Heat exchange between the flue gas and reformate streams through the reformer reactor walls was also included as a conjugate heat transfer process.  From a review of published models for the catalytic steam reforming of ethanol and preliminary predictions...

  6. Development and verification of a space-dependent dynamic model of a natural circulation steam generator

    International Nuclear Information System (INIS)

    Mewdell, C.G.; Harrison, W.C.; Hawley, E.H.

    1980-01-01

    This paper describes the development and verification of a Non-Linear Space-Dependent Dynamic Model of a Natural Circulation Steam Generator typical of boilers used in CANDU nuclear power stations. The model contains a detailed one-dimensional dynamic description of both the primary and secondary sides of an integral pre-heater natural circulation boiler. Two-phase flow effects on the primary side are included. The secondary side uses a drift-flux model in the boiling sections and a detailed non-equilibrium point model for the steam drum. The paper presents the essential features of the final model called BOILER-2, its solution scheme, the RD-12 loop and test boiler, the boiler steady-state and transient experiments, and the comparison of the model predictions with experimental results. (author)

  7. Thermodynamic modeling of the power plant based on the SOFC with internal steam reforming of methane

    International Nuclear Information System (INIS)

    Ivanov, Peter

    2007-01-01

    Mathematical model based on the thermodynamic modeling of gaseous mixtures is developed for SOFC with internal steam reforming of methane. Macroscopic porous-electrode theory, including non-linear kinetics and gas-phase diffusion, is used to calculate the reforming reaction and the concentration polarization. Provided the data concerning properties and costs of materials the model is fit for wide range of parametric analysis of thermodynamic cycles including SOFC

  8. Optimization of steam generator replacement with virtual reality modeling

    International Nuclear Information System (INIS)

    Kim, Jeong H.; Suh, Kune Y.

    2008-01-01

    Nuclear power plants (NPPs) have to be carefully examined and maintained up to the point of replacing major components during the overhaul period for continued operation. Most understandably the cost of maintenance and upgrading will tend to increase with the NPP power. There is thus an escalating need for developing an optimized process management method to reduce the cost involved. Albeit the steam generators (SGs) may not directly affect the expected lifespan of NPP, thousands of tubes with diameter on the order of 3 cm in the SG operating at 320degC and 16 MPa may well tend to be called Achilles' heel of the pressurized water reactors (PWRs). For instance, the SGs of Kori Nuclear Unit 1 (KNU 1) were replaced in October 1998 after 20 years of service on account of aging and potential threat to operational safety. In the same year the SG tubes of Ulchin Nuclear Units 1 and 2 were ruptured to result in leakage of the primary coolant to the secondary side. As a result their SGs are planned to be replaced in a few years. There is, however, a limit to improving the replacement process by trial and error in practice on account of the size of NPP with the ensuing complexity in process management. This paper proposes an optimization method for the SG replacement process based on the KNU 1 experience in 1998. The whole process was simulated accounting for interactions of each part in virtual reality utilizing the computer aided design solution CATIA, and the digital process management solution DELMIA. (author)

  9. About the Sterilization of Chitosan Hydrogel Nanoparticles.

    Directory of Open Access Journals (Sweden)

    Raquel Galante

    Full Text Available In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation, a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP hydrogel nanoparticles (CS-HNP, with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol. Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

  10. About the Sterilization of Chitosan Hydrogel Nanoparticles.

    Science.gov (United States)

    Galante, Raquel; Rediguieri, Carolina F; Kikuchi, Irene Satiko; Vasquez, Pablo A S; Colaço, Rogério; Serro, Ana Paula; Pinto, Terezinha J A

    2016-01-01

    In the last years, nanostructured biomaterials have raised a great interest as platforms for delivery of drugs, genes, imaging agents and for tissue engineering applications. In particular, hydrogel nanoparticles (HNP) associate the distinctive features of hydrogels (high water uptake capacity, biocompatibility) with the advantages of being possible to tailor its physicochemical properties at nano-scale to increase solubility, immunocompatibility and cellular uptake. In order to be safe, HNP for biomedical applications, such as injectable or ophthalmic formulations, must be sterile. Literature is very scarce with respect to sterilization effects on nanostructured systems, and even more in what concerns HNP. This work aims to evaluate the effect and effectiveness of different sterilization methods on chitosan (CS) hydrogel nanoparticles. In addition to conventional methods (steam autoclave and gamma irradiation), a recent ozone-based method of sterilization was also tested. A model chitosan-tripolyphosphate (TPP) hydrogel nanoparticles (CS-HNP), with a broad spectrum of possible applications was produced and sterilized in the absence and in the presence of protective sugars (glucose and mannitol). Properties like size, zeta potential, absorbance, morphology, chemical structure and cytotoxicity were evaluated. It was found that the CS-HNP degrade by autoclaving and that sugars have no protective effect. Concerning gamma irradiation, the formation of agglomerates was observed, compromising the suspension stability. However, the nanoparticles resistance increases considerably in the presence of the sugars. Ozone sterilization did not lead to significant physical adverse effects, however, slight toxicity signs were observed, contrarily to gamma irradiation where no detectable changes on cells were found. Ozonation in the presence of sugars avoided cytotoxicity. Nevertheless, some chemical alterations were observed in the nanoparticles.

  11. An Isothermal Steam Expander for an Industrial Steam Supplying System

    Directory of Open Access Journals (Sweden)

    Chen-Kuang Lin

    2015-01-01

    Full Text Available Steam is an essential medium used in the industrial process. To ensure steam quality, small and middle scale boilers are often adopted. However, because a higher steam pressure (compared to the necessary steam pressure is generated, the boiler’s steam pressure will be reduced via a pressure regulator before the steam is directed through the process. Unfortunately, pressure is somewhat wasted during the reducing process. Therefore, in order to promote energy efficiency, a pressure regulator is replaced by a steam expander. With this steam expander, the pressure will be transformed into mechanical energy and extracted during the expansion process. A new type of isothermal steam expander for an industrial steam supplying system will be presented in the paper. The isothermal steam expander will improve the energy efficiency of a traditional steam expander by replacing the isentropic process with an isothermal expansion process. With this, steam condensation will decrease, energy will increase, and steam quality will be improved. Moreover, the mathematical model of the isothermal steam expander will be established by using the Schmidt theory, the same principle used to analyze Stirling engines. Consequently, by verifying the correctness of the theoretical model for the isothermal steam expander using experimental data, a prototype of 100 c.c. isothermal steam expander is constructed.

  12. Steam Generator Analysis Tools and Modeling of Degradation Mechanisms

    International Nuclear Information System (INIS)

    Yetisir, M.; Pietralik, J.; Tapping, R.L.

    2004-01-01

    The degradation of steam generators (SGs) has a significant effect on nuclear heat transport system effectiveness and the lifetime and overall efficiency of a nuclear power plant. Hence, quantification of the effects of degradation mechanisms is an integral part of a SG degradation management strategy. Numerical analysis tools such as THIRST, a 3-dimensional (3D) thermal hydraulics code for recirculating SGs; SLUDGE, a 3D sludge prediction code; CHECWORKS a flow-accelerated corrosion prediction code for nuclear piping, PIPO-FE, a SG tube vibration code; and VIBIC and H3DMAP, 3D non-linear finite-element codes to predict SG tube fretting wear can be used to assess the impacts of various maintenance activities on SG thermal performance. These tools are also found to be invaluable at the design stage to influence the design by determining margins or by helping the designers minimize or avoid known degradation mechanisms. In this paper, the aforementioned numerical tools and their application to degradation mechanisms in CANDU recirculating SGs are described. In addition, the following degradation mechanisms are identified and their effect on SG thermal efficiency and lifetime are quantified: primary-side fouling, secondary-side fouling, fretting wear, and flow-accelerated corrosion (FAC). Primary-side tube inner diameter fouling has been a major contributor to SG thermal degradation. Using the results of thermalhydraulic analysis and field data, fouling margins are calculated. Individual effects of primary- and secondary-side fouling are separated through analyses, which allow station operators to decide what type of maintenance activity to perform and when to perform the maintenance activity. Prediction of the fretting-wear rate of tubes allows designers to decide on the number and locations of support plates and U-bend supports. The prediction of FAC rates for SG internals allows designers to select proper materials, and allows operators to adjust the SG maintenance

  13. A four-region, moving-boundary model of a once-through, helical-coil steam generator

    International Nuclear Information System (INIS)

    Abdalla, M.A.

    1994-01-01

    A dynamic model of a once-through, helical-coil steam generator is presented. The model simulates the advanced liquid metal reactor superheated cycle steam generator with a four-region, moving-boundary, draft-flux flow model. The model is described by a set of nonlinear differential equations derived from the fundamental equations of conservation of mass, energy, and momentum. Sample results of steady-state and transient calculations are presented. (author)

  14. An effective continuum damage mechanics model for creep-fatigue life assessment of a steam turbine rotor

    International Nuclear Information System (INIS)

    JianPing, Jing; Guang, Meng; Yi, Sun; SongBo, Xia

    2003-01-01

    A nonlinear Continuum Damage Mechanics model is proposed to assess the creep-fatigue life of a steam turbine rotor, in which the effects of complex multiaxial stress and the coupling of fatigue and creep are taken into account. The nonlinear evolution of damage is also considered. The model is applied to a 600 MW steam turbine under a practical start-stop operation. The results are compared with those from the linear accumulation theory that is dominant in life assessment of steam turbine rotors at present. The comparison show that the nonlinear continuum damage mechanics model describes the accumulation and development of damage better than the linear accumulation theory

  15. Theoretical-empirical model of the steam-water cycle of the power unit

    Directory of Open Access Journals (Sweden)

    Grzegorz Szapajko

    2010-06-01

    Full Text Available The diagnostics of the energy conversion systems’ operation is realised as a result of collecting, processing, evaluatingand analysing the measurement signals. The result of the analysis is the determination of the process state. It requires a usageof the thermal processes models. Construction of the analytical model with the auxiliary empirical functions built-in brings satisfyingresults. The paper presents theoretical-empirical model of the steam-water cycle. Worked out mathematical simulation model containspartial models of the turbine, the regenerative heat exchangers and the condenser. Statistical verification of the model is presented.

  16. Sterilization System

    Science.gov (United States)

    1990-01-01

    Cox Sterile Products, Inc.'s Rapid Heat Transfer Sterilizer employs a heat exchange process that induces rapid air movement; the air becomes the heat transfer medium, maintaining a uniform temperature of 375 degrees Fahrenheit. It features pushbutton controls for three timing cycles for different instrument loads, a six-minute cycle for standard unpackaged instruments, eight minutes for certain specialized dental/medical instruments and 12 minutes for packaged instruments which can then be stored in a drawer in sterile condition. System will stay at 375 degrees all day. Continuous operation is not expensive because of the sterilizer's very low power requirements.

  17. Aroma behaviour during steam cooking within a potato starch-based model matrix.

    Science.gov (United States)

    Descours, Emilie; Hambleton, Alicia; Kurek, Mia; Debeaufort, Fréderic; Voilley, Andrée; Seuvre, Anne-Marie

    2013-06-05

    To help understand the organoleptic qualities of steam cooked foods, the kinetics of aroma release during cooking in a potato starch based model matrix was studied. Behaviour of components having a major impact in potato flavour were studied using solid phase micro extraction-gas chromatography (SPME-GC). Evolution of microstructure of potato starch model-matrix during steam cooking process was analyzed using environmental scanning electron microscopy (ESEM). Both aroma compounds that are naturally present in starch matrix and those that were added were analyzed. Both the aroma compounds naturally presented and those added had different behaviour depending on their physico-chemical properties (hydrophobicity, saturation vapour pressure, molecular weight, etc.). The physical state of potato starch influences of the retention of aromatized matrix with Starch gelatinization appearing to be the major phenomenon influencing aroma release. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Computational Fluid Dynamic Model of Steam Ingestion into a Transonic Compressor

    Science.gov (United States)

    2009-06-01

    analysis of the final blade model compared to actual violin bow testing on the rotor blades with a microphone-amplifier-spectrum analyzer by O’Brien...it mimicked the physical experimental throttling technique . These boundary conditions represent the default setup for all the simulations in this...physical experiment, which showed that CFD techniques can be used to estimate the stall reduction between throttle and steam-induced stall. Though

  19. Solar tower power plant using a particle-heated steam generator: Modeling and parametric study

    Science.gov (United States)

    Krüger, Michael; Bartsch, Philipp; Pointner, Harald; Zunft, Stefan

    2016-05-01

    Within the framework of the project HiTExStor II, a system model for the entire power plant consisting of volumetric air receiver, air-sand heat exchanger, sand storage system, steam generator and water-steam cycle was implemented in software "Ebsilon Professional". As a steam generator, the two technologies fluidized bed cooler and moving bed heat exchangers were considered. Physical models for the non-conventional power plant components as air- sand heat exchanger, fluidized bed coolers and moving bed heat exchanger had to be created and implemented in the simulation environment. Using the simulation model for the power plant, the individual components and subassemblies have been designed and the operating parameters were optimized in extensive parametric studies in terms of the essential degrees of freedom. The annual net electricity output for different systems was determined in annual performance calculations at a selected location (Huelva, Spain) using the optimized values for the studied parameters. The solution with moderate regenerative feed water heating has been found the most advantageous. Furthermore, the system with moving bed heat exchanger prevails over the system with fluidized bed cooler due to a 6 % higher net electricity yield.

  20. Sterile neutrino in a minimal three-generation see-saw model

    Indian Academy of Sciences (India)

    Sterile neutrino in a minimal three-generation see-saw model. Table 1. Relevant right-handed fermion and scalar fields and their transformation properties. Here we have defined Y. I3R· (B–L)/2. SU´2µL ¢U´1µI3R ¢U´1µB L. SU´2µL ¢UY ´1µ. Le ·Lµ Lτ. Seµ. 2R ν R. (1,1/2, 1). (1,0). 1. 1 ν·R. (1,1/2, 1). (1,0). 1. 1. ντR. (1, 1/2, 1).

  1. Fate of Staphylococcus aureus in radiation sterilized model food systems simulating dairy products

    International Nuclear Information System (INIS)

    Sulebele, G.A.; Kamat, M.Y.

    1976-01-01

    Gamma irradiation was successfully employed for the development of sterile model food systems simulating dairy products such as pedha and cottage cheese which were inoculated with enterotoxigenic S.aureus S-6 and FR1-100 either individually or in association with S.epidermids and other mixed flora comprising of gram-positive, gram-negative and lactic bacteria and stored at 4 and 35 degC for 6-8 weeks. Pedha failed to support growth of S.aureus while cottage cheese favoured profuse growth of the pathogen. S.epidermidis exhibited a synergistic effect on the growth of S.aureus in cottage cheese. Baired-Parker's medium showed very poor recovery of S.aureus which necessitated the development of a new selective medium for the enumeration of staphylococci in processed foods. (author)

  2. Modelling of blowdown of steam in the pressurized PPOOLEX facility

    International Nuclear Information System (INIS)

    Paettikangas, T.; Niemi, J.; Timperi, A.

    2009-12-01

    PPOOLEX experiment WLL-04-02 on condensation of vapour is studied with CFD simulations. Wall condensation model has been adapted to an Euler-Euler multiphase model of the Fluent CFD code for this purpose. In addition, a simple direct-contact condensation model has also been included in the code. The main focus of the CFD modelling work was on modelling condensation in the drywell. The amount of condensation found in the CFD calculation was in fair agreement with the experiment. The present simulation was so short that the gas flowing into the wetwell contained significant amount of air. The mole fraction of vapour at the outlet of the vent pipe had the maximum value of about 0.3. Therefore, the noncondensable gas strongly affected the direct-contact condensation in the water pool. Much longer simulations are needed in order to study jugging and condensation oscillations. FSI calculations of the experiments were performed by using the Star-CD, ABAQUS and MpCCI codes. An approximate method that makes possible numerically stable FSI calculations for the experimental facilities was used. The method is based on linear perturbation method which necessitates small structural deformations. The calculations showed that FSI has to be taken into account for the POOLEX facility which has relatively light structures. A way for determining the pressure source for the acoustic model from pressure measured at the pool bottom was also examined. Separation of the pressure component due to wall motion from the blowdown load was attempted by conducting a Fourier analysis on the measured displacement signal. The study showed that in practise sufficiently accurate acceleration signal cannot be obtained this way because the transformed signal gets easily out of phase. A measurement system was proposed which could be used for determining the pressure fluctuations. (author)

  3. Modelling of blowdown of steam in the pressurized PPOOLEX facility

    Energy Technology Data Exchange (ETDEWEB)

    Paettikangas, T.; Niemi, J.; Timperi, A. (VTT Technical Research Centre of Finland (Finland))

    2009-12-15

    PPOOLEX experiment WLL-04-02 on condensation of vapour is studied with CFD simulations. Wall condensation model has been adapted to an Euler-Euler multiphase model of the Fluent CFD code for this purpose. In addition, a simple direct-contact condensation model has also been included in the code. The main focus of the CFD modelling work was on modelling condensation in the drywell. The amount of condensation found in the CFD calculation was in fair agreement with the experiment. The present simulation was so short that the gas flowing into the wetwell contained significant amount of air. The mole fraction of vapour at the outlet of the vent pipe had the maximum value of about 0.3. Therefore, the noncondensable gas strongly affected the direct-contact condensation in the water pool. Much longer simulations are needed in order to study jugging and condensation oscillations. FSI calculations of the experiments were performed by using the Star-CD, ABAQUS and MpCCI codes. An approximate method that makes possible numerically stable FSI calculations for the experimental facilities was used. The method is based on linear perturbation method which necessitates small structural deformations. The calculations showed that FSI has to be taken into account for the POOLEX facility which has relatively light structures. A way for determining the pressure source for the acoustic model from pressure measured at the pool bottom was also examined. Separation of the pressure component due to wall motion from the blowdown load was attempted by conducting a Fourier analysis on the measured displacement signal. The study showed that in practise sufficiently accurate acceleration signal cannot be obtained this way because the transformed signal gets easily out of phase. A measurement system was proposed which could be used for determining the pressure fluctuations. (author)

  4. CREATION OF OPTIMIZATION MODEL OF STEAM BOILER RECUPERATIVE AIR HEATER

    Directory of Open Access Journals (Sweden)

    N. B. Carnickiy

    2006-01-01

    Full Text Available The paper proposes to use a mathematical modeling as one of the ways intended to improve quality of recuperative air heater design (RAH without significant additional costs, connected with the change of design materials or fuel type. The described conceptual mathematical AHP optimization model of RAH consists of optimized and constant parameters, technical limitations and optimality criteria.The paper considers a methodology for search of design and regime parameters of an air heater which is based on the methods of multi-criteria optimization. Conclusions for expediency of the given approach usage are made in the paper.

  5. Modelling of Zircaloy-steam-oxidation under severe fuel damage conditions

    International Nuclear Information System (INIS)

    Malang, S.; Neitzel, H.J.

    1983-01-01

    Small break loss-of-coolant accidents and special transients in an LWR, in combination with loss of required safety systems, may lead to an uncovered core for an extended period of time. As a consequence, the cladding temperature could rise up to the melting point due to the decay heat, resulting in severely damaged fuel rods. During heat-up the claddings oxidize due to oxygen uptake from the steam atmosphere in the core. The modeling and assessment of the Zircaloy-steam oxidation under such conditions is important, mainly for two reasons: The oxidation of the cladding influences the temperature transients due to the exothermic heat of reaction; the amount of liquified fuel depends on the oxide layer thickness and the oxygen content of the remaining Zircaloy metal when the melting point is reached. (author)

  6. Thermohidraulic model for a typical steam generator of PWR Nuclear Power Plants

    International Nuclear Information System (INIS)

    Braga, C.V.M.

    1980-06-01

    A model of thermohidraulic simulation, for steady state, considering the secondary flow divided in two parts individually homogeneous, and with heat and mass transferences between them is developed. The quality of the two-phase mixture that is fed to the turbine is fixed and, based on this value, the feedwater pressure is determined. The recirculation ratio is intrinsically determined. Based on this model it was developed the GEVAP code, in Fortran-IV language. The model is applied to the steam generator of the Angra II nuclear power plant and the results are compared with KWU'S design parameters, being considered satisfactory. (Author) [pt

  7. Modelling of the processes of heat and mass transfer in adiabatic steam and drop flows

    International Nuclear Information System (INIS)

    Andrizhievskij, A.A.; Mikhalevich, A.A.; Nesterenko, V.B.; Trifonov, A.G.

    1983-01-01

    The mathematical models for investigating the local and integral characteristics of heat and mass transfer processes during simultaneous motion of adiabatic steam and drop flow and a flux of impurity particles are given. The mathematical model is constrUcted on the basis of one-dimensional stationary eqUations of conservation of mass, thermal energy and momentum of liquid and vapor phases. Dispersion composition of condensed moisture is described by the Nukiyama-Tanasava distribution function formed taking into account the Veber number critical value. Equations of motion and mass balance conservation for impurity particles are included into the mathematical model. These equations are considered as additional inactive phase

  8. Application of the thermal-hydraulic codes in VVER-440 steam generators modelling

    Energy Technology Data Exchange (ETDEWEB)

    Matejovic, P.; Vranca, L.; Vaclav, E. [Nuclear Power Plant Research Inst. VUJE (Slovakia)

    1995-12-31

    Performances with the CATHARE2 V1.3U and RELAP5/MOD3.0 application to the VVER-440 SG modelling during normal conditions and during transient with secondary water lowering are described. Similar recirculation model was chosen for both codes. In the CATHARE calculation, no special measures were taken with the aim to optimize artificially flow rate distribution coefficients for the junction between SG riser and steam dome. Contrary to RELAP code, the CATHARE code is able to predict reasonable the secondary swell level in nominal conditions. Both codes are able to model properly natural phase separation on the SG water level. 6 refs.

  9. An Analytical Model for Simulating Heavy-Oil Recovery by Cyclic Steam Injection Using Horizontal Wells, SUPRI TR-118

    Energy Technology Data Exchange (ETDEWEB)

    Diwan, Utpal; Kovscek, Anthony R.

    1999-08-09

    In this investigation, existing analytical models for cyclic steam injection and oil recovery are reviewed and a new model is proposed that is applicable to horizontal wells. A new flow equation is developed for oil production during cyclic steaming of horizontal wells. The model accounts for the gravity-drainage of oil along the steam-oil interface and through the steam zone. Oil viscosity, effective permeability, geometry of the heated zone, porosity, mobile oil saturation, and thermal diffusivity of the reservoir influence the flow rate of oil in the model. The change in reservoir temperature with time is also modeled, and it results in the expected decline in oil production rate during the production cycle as the reservoir cools. Wherever appropriate, correlations and incorporated to minimize data requirements. A limited comparison to numerical simulation results agrees well, indicating that essential physics are successfully captured. Cyclic steaming appears to be a systematic met hod for heating a cold reservoir provided that a relatively uniform distribution of steam is obtained along the horizontal well during injection. A sensitivity analysis shows that the process is robust over the range of expected physical parameters.

  10. Bistable flow occurrence in the 2D model of a steam turbine valve

    Science.gov (United States)

    Pavel, Procházka; Václav, Uruba

    2017-09-01

    The internal flow inside a steam turbine valve was investigated experimentally using PIV measurement. The valve model was proposed to be two-dimensional. The model was connected to the blow-down wind tunnel. The flow conditions were set by the different position of the valve plug. Several angles of the diffuser by diverse radii were investigated concerning flow separation and flow dynamics. It was found that the flow takes one of two possible bistable modes. The first regime is characterized by a massive flow separation just at the beginning of the diffuser section on the one side. The second regime is axisymmetric and the flow separation is not detected at all.

  11. Identification of Super Phenix steam generator by a simple polynomial model

    International Nuclear Information System (INIS)

    Rousseau, I.

    1981-01-01

    This note suggests a method of identification for the steam generator of the Super-Phenix fast neutron power plant for simple polynomial models. This approach is justified in the selection of the adaptive control. The identification algorithms presented will be applied to multivariable input-output behaviours. The results obtained with the representation in self-regressive form and by simple polynomial models will be compared and the effect of perturbations on the output signal will be tested, in order to select a good identification algorithm for multivariable adaptive regulation [fr

  12. Sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Kopp, J. [PRISMA Cluster of Excellence & Mainz Institute for Theoretical Physics, Johannes Gutenberg University, 55099 Mainz (Germany); Machado, P. A. N., E-mail: pedro.machado@uam.es [Departamento de Física Teórica, Universidad Autónoma de Madrid, Cantoblanco E-28049 Madrid (Spain); Instituto de Física Teórica UAM/CSIC, Calle Nicolás Cabrera 13-15, Cantoblanco E-28049 Madrid (Spain); Maltoni, M. [Instituto de Física Teórica UAM/CSIC, Calle Nicolás Cabrera 13-15, Cantoblanco E-28049 Madrid (Spain); Schwetz, T. [Institute for Nuclear Physics, Karlsruhe Institute of Technology (KIT), Postfach 3640, 76021 Karlsruhe (Germany)

    2016-06-21

    We characterize statistically the indications of a presence of one or more light sterile neutrinos from MiniBooNE and LSND data, together with the reactor and gallium anomalies, in the global context. The compatibility of the aforementioned signals with null results from solar, atmospheric, reactor, and accelerator experiments is evaluated. We conclude that a severe tension is present in the global fit, and therefore the addition of eV-scale sterile neutrinos does not satisfactorily explain the anomalies.

  13. A Bayesian approach to modeling and predicting pitting flaws in steam generator tubes

    International Nuclear Information System (INIS)

    Yuan, X.-X.; Mao, D.; Pandey, M.D.

    2009-01-01

    Steam generators in nuclear power plants have experienced varying degrees of under-deposit pitting corrosion. A probabilistic model to accurately predict pitting damage is necessary for effective life-cycle management of steam generators. This paper presents an advanced probabilistic model of pitting corrosion characterizing the inherent randomness of the pitting process and measurement uncertainties of the in-service inspection (ISI) data obtained from eddy current (EC) inspections. A Markov chain Monte Carlo simulation-based Bayesian method, enhanced by a data augmentation technique, is developed for estimating the model parameters. The proposed model is able to predict the actual pit number, the actual pit depth as well as the maximum pit depth, which is the main interest of the pitting corrosion model. The study also reveals the significance of inspection uncertainties in the modeling of pitting flaws using the ISI data: Without considering the probability-of-detection issues and measurement errors, the leakage risk resulted from the pitting corrosion would be under-estimated, despite the fact that the actual pit depth would usually be over-estimated.

  14. U-tube steam generator empirical model development and validation using neural networks

    International Nuclear Information System (INIS)

    Parlos, A.G.; Chong, K.T.; Atiya, A.

    1992-01-01

    Empirical modeling techniques that use model structures motivated from neural networks research have proven effective in identifying complex process dynamics. A recurrent multilayer perception (RMLP) network was developed as a nonlinear state-space model structure along with a static learning algorithm for estimating the parameter associated with it. The methods developed were demonstrated by identifying two submodels of a U-tube steam generator (UTSG), each valid around an operating power level. A significant drawback of this approach is the long off-line training times required for the development of even a simplified model of a UTSG. Subsequently, a dynamic gradient descent-based learning algorithm was developed as an accelerated alternative to train an RMLP network for use in empirical modeling of power plants. The two main advantages of this learning algorithm are its ability to consider past error gradient information for future use and the two forward passes associated with its implementation. The enhanced learning capabilities provided by the dynamic gradient descent-based learning algorithm were demonstrated via the case study of a simple steam boiler power plant. In this paper, the dynamic gradient descent-based learning algorithm is used for the development and validation of a complete UTSG empirical model

  15. Introduction to sterile neutrinos

    Science.gov (United States)

    Volkas, R. R.

    2002-07-01

    Model-building issues raised by the prospect of light sterile neutrinos are discussed in a pedagogical way. I first review the naive proposal that sterile neutrinos be identified with “right handed neutrinos”. A critical discussion of the simple expedient of adding three gauge singlet fermions to the usual minimal standard model matter content is followed by an examination of right handed neutrinos in extended theories. I introduce the terminology of “fully sterile” and “weakly sterile” to classify varieties usually conflated under the sterile neutrino banner. After introducing the concepts of “technical naturalness” and plain “naturalness”, the unbearable lightness of being a sterile neutrino is confronted. This problem is used to motivate mirror neutrinos, whose connection with pairwise maximal mixing is emphasised. Some brief remarks about phenomenology are made throughout. The impossibility of identifying the sole sterile neutrino of the currently favoured 2 + 2 and 3 + 1 phenomenological constructs as a lone gauge singlet fermion added to the minimal standard model is explained. Finally, I remark on the beauty and subtlety of light sterile neutrino cosmology.

  16. Predictive models for deposit accumulation and corrosion on secondary side of steam generators

    International Nuclear Information System (INIS)

    Choi, Samuel; Moroney, Velvet; Marks, Chuck; Kreider, Marc

    2012-09-01

    Experience demonstrates that deposit accumulation in steam generators (SGs) can lead to corrosion of tubes. To minimize the probability of this corrosion, utilities employ a variety of deposit control strategies. However, these processes can involve significant costs and potentially affect outage critical paths. Since there has been no model that quantifies tube degradation as a function of deposit accumulation, utilities have had to make decisions regarding deposit control strategies without a reliable quantitative basis. The objective of this study is to develop methods that utilities can use to quantify benefits of SG deposit control strategies with regard to rates of secondary-side tube corrosion. Two different methodologies are employed in this work. The first methodology is empirical and is involved an attempt to correlate degradation rates with deposit accumulation as indicated by sludge pile height. Because there has been relatively little tube degradation in currently operating steam generators, this correlation is developed using data for Alloy 600MA SG tubes. To increase the number of units that could be used for defect/deposit correlations, a method to relate the sludge pile deposit mass and the number of tubes with non-zero sludge height is developed. The second methodology is theoretical and is based on the use of calculated differences in temperature and chemistry to predict the effect of deposits on corrosion rates. Computational fluid dynamics (CFD) models are developed to simulate thermal-hydraulic conditions representative of conditions that are present within porous deposits formed at the top of tube sheet. This paper will discuss the development and application of the predictive models for deposit accumulation and corrosion on the secondary side of steam generators. (authors)

  17. Model-Free Coordinated Control for MHTGR-Based Nuclear Steam Supply Systems

    Directory of Open Access Journals (Sweden)

    Zhe Dong

    2016-01-01

    Full Text Available The modular high temperature gas-cooled reactor (MHTGR is a typical small modular reactor (SMR that offers simpler, standardized and safer modular design by being factory built, requiring smaller initial capital investment, and having a shorter construction period. Thanks to its small size, the MHTGRs could be beneficial in providing electric power to remote areas that are deficient in transmission or distribution and in generating local power for large population centers. Based on the multi-modular operation scheme, the inherent safety feature of the MHTGRs can be applicable to large nuclear plants of any desired power rating. The MHTGR-based nuclear steam supplying system (NSSS is constituted by an MHTGR, a side-by-side arranged helical-coil once-through steam generator (OTSG and some connecting pipes. Due to the side-by-side arrangement, there is a tight coupling effect between the MHTGR and OTSG. Moreover, there always exists the parameter perturbation of the NSSSs. Thus, it is meaningful to study the model-free coordinated control of MHTGR-based NSSSs for safe, stable, robust and efficient operation. In this paper, a new model-free coordinated control strategy that regulates the nuclear power, MHTGR outlet helium temperature and OTSG outlet overheated steam temperature by properly adjusting the control rod position, helium flowrate and feed-water flowrate is established for the MHTGR-based NSSSs. Sufficient conditions for the globally asymptotic closed-loop stability is given. Finally, numerical simulation results in the cases of large range power decrease and increase illustrate the satisfactory performance of this newly-developed model-free coordinated NSSS control law.

  18. Programme PROPANA: A model of the propagation of water leaks into sodium in steam generators

    International Nuclear Information System (INIS)

    Maupre, J.P.; McCrindle, K.B.

    1990-01-01

    The programme PROPANA presented in this paper is a two dimensional programme which models the propagation of water leaks in the Steam Generators of Sodium Cooled Reactors. It models the phenomena of self-evolution of leaks and the erosion and corrosion of target tubes by ''wastage'' leading to the creation of secondary defects. It includes models of leak detection and SGU depressurization. It is able to calculate the damage ia a SGU tube bundle up to the end of the depressurization for different leak scenario. In its current form it does not model the failure of tubes due to overheating which is the object of the programme MECTUB. Future developments of PROPANA include the addition of MECTUB to allow the combined effects of wastage and overheating to be modelled. 16 refs, 8 figs

  19. Probability of detection model for the non-destructive inspection of steam generator tubes of PWRs

    Science.gov (United States)

    Yusa, N.

    2017-06-01

    This study proposes a probability of detection (POD) model to discuss the capability of non-destructive testing methods for the detection of stress corrosion cracks appearing in the steam generator tubes of pressurized water reactors. Three-dimensional finite element simulations were conducted to evaluate eddy current signals due to stress corrosion cracks. The simulations consider an absolute type pancake probe and model a stress corrosion crack as a region with a certain electrical conductivity inside to account for eddy currents flowing across a flaw. The probabilistic nature of a non-destructive test is simulated by varying the electrical conductivity of the modelled stress corrosion cracking. A two-dimensional POD model, which provides the POD as a function of the depth and length of a flaw, is presented together with a conventional POD model characterizing a flaw using a single parameter. The effect of the number of the samples on the PODs is also discussed.

  20. Experimental modeling of flow-induced vibration of multi-span U-tubes in a CANDU steam generator

    International Nuclear Information System (INIS)

    Mohany, A.; Feenstra, P.; Janzen, V.P.; Richard, R.

    2009-01-01

    Flow-induced vibration of the tubes in a nuclear steam generator is a concern for designers who are trying to increase the life span of these units. The dominant excitation mechanisms are fluidelastic instability and random turbulence excitation. The outermost U-bend region of the tubes is of greatest concern because the flow is almost perpendicular to the tube axis and the unsupported span is relatively long. The support system in this region must be well designed in order to minimize fretting wear of the tubes at the support locations. Much of the previous testing was conducted on straight single-span or cantilevered tubes in cross-flow. However, the dynamic response of steam generator multi-span U-tubes with clearance supports is expected to be different. Accurate modeling of the tube dynamics is important to properly simulate the dynamic interaction of the tube and supports. This paper describes a test program that was developed to measure the dynamic response of a bundle of steam generator U-tubes with Anti-Vibration Bar (AVB) supports, subjected to Freon two-phase cross-flow. The tube bundle has similar geometrical conditions to those expected for future CANDU steam generators. Future steam generators will be larger than previous CANDU steam generators, nearly twice the heat transfer area, with significant changes in process conditions in the U-bend region, such as increased steam quality and a broader range of flow velocities. This test program was initiated at AECL to demonstrate that the tube support design for future CANDU steam generators will meet the stringent requirements associated with a 60 year design life. The main objective of the tests is to address the issue of in-plane and out-of-plane fluidelastic instability and random turbulent excitation of a U-tube bundle with Anti-Vibration Bar (AVB) supports. Details of the test rig, measurement techniques and preliminary instrumentation results are described in the paper. (author)

  1. Resonantly produced 7 keV sterile neutrino dark matter models and the properties of Milky Way satellites.

    Science.gov (United States)

    Abazajian, Kevork N

    2014-04-25

    Sterile neutrinos produced through a resonant Shi-Fuller mechanism are arguably the simplest model for a dark matter interpretation of the origin of the recent unidentified x-ray line seen toward a number of objects harboring dark matter. Here, I calculate the exact parameters required in this mechanism to produce the signal. The suppression of small-scale structure predicted by these models is consistent with Local Group and high-z galaxy count constraints. Very significantly, the parameters necessary in these models to produce the full dark matter density fulfill previously determined requirements to successfully match the Milky Way Galaxy's total satellite abundance, the satellites' radial distribution, and their mass density profile, or the "too-big-to-fail problem." I also discuss how further precision determinations of the detailed properties of the candidate sterile neutrino dark matter can probe the nature of the quark-hadron transition, which takes place during the dark matter production.

  2. Kinetic models comparison for steam gasification of coal/biomass blend chars.

    Science.gov (United States)

    Xu, Chaofen; Hu, Song; Xiang, Jun; Yang, Haiping; Sun, Lushi; Su, Sheng; Wang, Baowen; Chen, Qindong; He, Limo

    2014-11-01

    The non-isothermal thermogravimetric method (TGA) was applied to different chars produced from lignite (LN), sawdust (SD) and their blends at the different mass ratios in order to investigate their thermal reactivity under steam atmosphere. Through TGA analysis, it was determined that the most prominent interaction between sawdust and lignite occurred at the mass ratio of sawdust/lignite as 1:4, but with further dose of more sawdust into its blends with lignite, the positive interaction deteriorated due to the agglomeration and deactivation of the alkali mineral involved in sawdust at high steam gasification temperature. Through systematic comparison, it could be observed that the random pore model was the most suitable among the three gas-solid reaction models adopted in this research. Finally, rational kinetic parameters were reached from these gas-solid reaction models, which provided a basis for design and operation of the realistic system of co-gasification of lignite and sawdust in this research. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Main steam line break accident simulation of APR1400 using the model of ATLAS facility

    Science.gov (United States)

    Ekariansyah, A. S.; Deswandri; Sunaryo, Geni R.

    2018-02-01

    A main steam line break simulation for APR1400 as an advanced design of PWR has been performed using the RELAP5 code. The simulation was conducted in a model of thermal-hydraulic test facility called as ATLAS, which represents a scaled down facility of the APR1400 design. The main steam line break event is described in a open-access safety report document, in which initial conditions and assumptionsfor the analysis were utilized in performing the simulation and analysis of the selected parameter. The objective of this work was to conduct a benchmark activities by comparing the simulation results of the CESEC-III code as a conservative approach code with the results of RELAP5 as a best-estimate code. Based on the simulation results, a general similarity in the behavior of selected parameters was observed between the two codes. However the degree of accuracy still needs further research an analysis by comparing with the other best-estimate code. Uncertainties arising from the ATLAS model should be minimized by taking into account much more specific data in developing the APR1400 model.

  4. Predictions and measurements of isothermal airflow in a model once-through steam generator

    Energy Technology Data Exchange (ETDEWEB)

    Carter, H R; Promey, G J; Rush, G C

    1982-11-01

    Once-Through Steam Generators (OTSGs) are used in the Nuclear Steam Supply Systems marketed by The Babcock and Wilcox Company (B and W). To analytically predict the three-dimensional, steady-state thermohydraulic conditions in the OTSG, B and W has developed a proprietary code THEDA-1 and is working in cooperation with EPRI to develop an improved version, THEDA-2. Confident application of THEDA requires experimental verification to demonstrate that the code can accurately describe the thermohydraulic conditions in geometries characteristic of the OTSG. The first step in the THEDA verification process is the subject of this report. A full-scale, partial-section model of two OTSG spans was constructed and tested using isothermal air as the working fluid. Model local velocities and pressure profiles were measured and compared to THEDA prediction for five model configurations. Over 3000 velocity measurements were taken and the results were compared to THEDA predictions. Agreement between measured and predicted velocity data was generally better than +-12.5%.

  5. A dynamic model for the steam generator of the Fast Breeder Test Reactor

    International Nuclear Information System (INIS)

    Kumar, S.S.; Kothaandaraman, A.L.; Ravi Prasan, G.R.

    1978-11-01

    A computer code for the thermal-hydraulic dynamics of the steam generator of the Fast Breeder Test Reactor Plant has been written. This report describes the physical, mathematical and computational models used. Some results are listed which bring out the usefulness of this code as the prerequisite for the estimation of thermal stresses and determination of safe operating modes. Problems of slip and non-uniform radial distribution are neglected because of the high pressure of operation and low pressure drop. By suitable decoupling of some of the equations of the model, the computational effort is reduced to the solution of a system of linear equations or one non-linear equation. The non-linear equation is solved by the method of false position and the method of binary division. Results are listed for the perturbations in sodium temperature, sodium flow, water flow and steam pressure. The computer code is written in Fortran IV and is operational on IBM 370/155 system. (auth.)

  6. Approximating Optimal Release in a Deterministic Model for the Sterile Insect Technique

    Directory of Open Access Journals (Sweden)

    Sergio Ramirez

    2016-01-01

    Full Text Available Cost/benefit analyses are essential to support management planning and decisions before launching any pest control program. In particular, applications of the sterile insect technique (SIT are often prevented by the projected economic burden associated with rearing processes. This has had a deep impact on the technique development and its use on insects with long larval periods, as often seen in beetles. Under the assumptions of long adult timespan and multiple mating, we show how to find approximate optimal sterile release policies that minimize costs. The theoretical framework proposed considers the release of insects by pulses and finds approximate optimal release sizes through stochastic searching. The scheme is then used to compare simulated release strategies obtained for different pulse schedules and release bounds, providing a platform for evaluating the convenience of increasing sterile male release intensity or extending the period of control.

  7. Scale model test results for an inverted U-tube steam generator with comparisons to heat transfer correlations

    International Nuclear Information System (INIS)

    Boucher, T.J.

    1987-01-01

    To provide data for assessment and development of thermal-hydraulic computer codes, bottom main feedwater-line-break transient simulations were performed in a scale model (Semiscale Mod-2C) of a pressurized water reactor (PWR) with conditions typical of a PWR (15.0 MPa primary pressure, 600 K steam generator inlet plenum fluid temperatures, 6.2 MPa secondary pressure). The state-of-the-art measurements in the scale model (Type III) steam generator allow for the determination of U-tube steam generator allow for the determination of U-tube steam generator secondary component interactions, tube bundle local radial heat transfer, and tube bundle and riser vapor void fractions for steady state and transient operations. To enhance the understanding of the observed phenomena, the component interactions, local heat fluxes, local secondary convective heat transfer coefficients and local vapor void fractions are discussed for steady state, full-power and transient operations. Comparisons between the measurement-derived secondary convective heat transfer coefficients and those predicted by a number of correlations, including the Chen correlation currently used in thermal-hydraulic computer codes, show that none of the correlations adequately predict the data and points out the need for the formulation of a new correlation based on this experimental data. The unique information presented herein should be of the interest to anyone involved in modeling inverted U-tube steam generator thermal-hydraulics for forced convection boiling/vaporization heat transfer. 5 refs., 13 figs., 1 tab

  8. Exploring a nonminimal sterile neutrino model involving decay at IceCube

    Science.gov (United States)

    Moss, Z.; Moulai, M. H.; Argüelles, C. A.; Conrad, J. M.

    2018-03-01

    We study the phenomenology of neutrino decay together with neutrino oscillations in the context of eV-scale sterile neutrinos. We review the formalism of visible neutrino decay in which one of the decay products is a neutrino that potentially can be observed. We apply the formalism developed for decay to the recent sterile neutrino search performed by IceCube with TeV neutrinos. We show that for a ν4 lifetime τ4/m4≲10-16 eV-1 s , the interpretation of the high-energy IceCube analysis can be significantly changed.

  9. Model-Based Interpretation and Experimental Verification of ECT Signals of Steam Generator Tubes

    International Nuclear Information System (INIS)

    Song, Sung Jin; Kim, Young Hwan; Kim, Eui Lae; Yim, Chang Jae; Lee, Jin Ho

    2004-01-01

    Model-based inversion tools for eddy current signals have been developed by combining neural networks and finite element modeling, for quantitative flaw characterization in steam generator tubes. In the present work, interpretation of experimental eddy current signals was carried out in order to validate the developed inversion tools. A database was constructed using the synthetic flaw signals generated by the finite element model. The hybrid neural networks composed of a PNN classifier and BPNN size estimators were trained using the synthetic signals. Experimental eddy current signals were obtained from axisymmetric artificial flaws. Interpretation of flaw signals was conducted by feeding the experimental signals into the neural networks. The interpretation was excellent, which shows that the developed inversion tools would be applicable to the Interpretation of real eddy current signals

  10. Kinetic Modeling of the Release of Ethylene Oxide from Sterilized Plastic Containers and its Interaction with Monoclonal Antibodies.

    Science.gov (United States)

    Yu, Bryan Lei; Han, Jun; Hammond, Matthew; Wang, Xuemei; Zhang, Qingchun; Clausen, Andrew; Forster, Ronald; Eu, Mingda

    Ethylene oxide (ETO) is commonly used to sterilize plastic containers, but the effects of residual amounts left after sterilization on protein therapeutics are still not well understood. Here we focus primarily on the factors that influence concentrations of ETO migrating from ETO-treated plastic containers into aqueous solution. A study was designed to investigate the kinetics of this process at various temperatures, and the kinetic data could be fit with a model based on a combination of Fickean diffusion and first-order chemical reaction (to account for observed hydrolysis of ETO). The diffusion and reaction rate constants thus obtained obey Arrhenius-like temperature dependence. These results indicate that for analytical methods involving extraction into water, measurements of residual ETO in a container must account for the effects of ETO hydrolysis. Further, the effects of salt concentration and pH of the fluid in the container on accumulated ETO levels were explored. Finally, interactions of ETO with anti-streptavidin (AntiSA) Immunoglobulin G1 (IgG1) and IgG2 antibodies were studied, with ETO adducts found on all methionine residues when incubated in solutions spiked with ETO at concentrations that could be reached (based on the kinetic studies) in ETO-treated plastic vials. Overall, the likelihood of observable ETO-protein modifications upon storage in ETO-sterilized containers will depend on a complex interplay of protein properties, formulation details, storage conditions, and amount of residual ETO initially in the container. Ethylene oxide (ETO) is commonly used to sterilize plastic containers, but the effects of residual amounts left after sterilization on protein therapeutics are still not well understood. Here we describe experiments exploring the factors that influence concentrations of ETO migrating from ETO-treated plastic containers into aqueous solution over time. Additionally, interactions of ETO with model antibodies were studied, with ETO

  11. Degradation of chitosan-based materials after different sterilization treatments

    Science.gov (United States)

    San Juan, A.; Montembault, A.; Gillet, D.; Say, J. P.; Rouif, S.; Bouet, T.; Royaud, I.; David, L.

    2012-02-01

    Biopolymers have received in recent years an increasing interest for their potential applications in the field of biomedical engineering. Among the natural polymers that have been experimented, chitosan is probably the most promising in view of its exceptional biological properties. Several techniques may be employed to sterilize chitosan-based materials. The aim of our study was to compare the effect of common sterilization treatments on the degradation of chitosan-based materials in various physical states: solutions, hydrogels and solid flakes. Four sterilization methods were compared: gamma irradiation, beta irradiation, exposure to ethylene oxide and saturated water steam sterilization (autoclaving). Exposure to gamma or beta irradiation was shown to induce an important degradation of chitosan, regardless of its physical state. The chemical structure of chitosan flakes was preserved after ethylene oxide sterilization, but this technique has a limited use for materials in the dry state. Saturated water steam sterilization of chitosan solutions led to an important depolymerization. Nevertheless, steam sterilization of chitosan flakes bagged or dispersed in water was found to preserve better the molecular weight of the polymer. Hence, the sterilization of chitosan flakes dispersed in water would represent an alternative step for the preparation of sterilized chitosan solutions. Alternatively, autoclaving chitosan physical hydrogels did not significantly modify the macromolecular structure of the polymer. Thus, this method is one of the most convenient procedures for the sterilization of physical chitosan hydrogels after their preparation.

  12. Degradation of chitosan-based materials after different sterilization treatments

    International Nuclear Information System (INIS)

    San Juan, A; Montembault, A; Royaud, I; David, L; Gillet, D; Say, J P; Rouif, S; Bouet, T

    2012-01-01

    Biopolymers have received in recent years an increasing interest for their potential applications in the field of biomedical engineering. Among the natural polymers that have been experimented, chitosan is probably the most promising in view of its exceptional biological properties. Several techniques may be employed to sterilize chitosan-based materials. The aim of our study was to compare the effect of common sterilization treatments on the degradation of chitosan-based materials in various physical states: solutions, hydrogels and solid flakes. Four sterilization methods were compared: gamma irradiation, beta irradiation, exposure to ethylene oxide and saturated water steam sterilization (autoclaving). Exposure to gamma or beta irradiation was shown to induce an important degradation of chitosan, regardless of its physical state. The chemical structure of chitosan flakes was preserved after ethylene oxide sterilization, but this technique has a limited use for materials in the dry state. Saturated water steam sterilization of chitosan solutions led to an important depolymerization. Nevertheless, steam sterilization of chitosan flakes bagged or dispersed in water was found to preserve better the molecular weight of the polymer. Hence, the sterilization of chitosan flakes dispersed in water would represent an alternative step for the preparation of sterilized chitosan solutions. Alternatively, autoclaving chitosan physical hydrogels did not significantly modify the macromolecular structure of the polymer. Thus, this method is one of the most convenient procedures for the sterilization of physical chitosan hydrogels after their preparation.

  13. Steam generator comprehensive testing facility

    International Nuclear Information System (INIS)

    Chen Changbing

    1998-12-01

    The main system and equipment of a capacity of 30 MW steam generator testing rig is briefly introduced. The thermal performance of steam generator simulator has been verified with a steam generator model comprehensive testing. The application and function of the Facility are analyzed. And the effective use of the equipment of the Facility is also proposed

  14. Modeling Creep-Fatigue-Environment Interactions in Steam Turbine Rotor Materials for Advanced Ultra-supercritical Coal Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Chen [General Electric Global Research, Niskayuna, NY (United States)

    2014-04-01

    The goal of this project is to model creep-fatigue-environment interactions in steam turbine rotor materials for advanced ultra-supercritical (A-USC) coal power Alloy 282 plants, to develop and demonstrate computational algorithms for alloy property predictions, and to determine and model key mechanisms that contribute to the damages caused by creep-fatigue-environment interactions.

  15. Sterile neutrino in a minimal three-generation see-saw model

    Indian Academy of Sciences (India)

    dimensional operators can induce mixing between left- and right-handed states which explains solar, atmospheric and LSND experimental results. Keywords. Sterile; neutrino; LSND. PACS Nos 12.60.Fr; 11.30.Hv; 13.15.+g. 1. Introduction and ...

  16. Sterile neutrino in a minimal three-generation see-saw model

    Indian Academy of Sciences (India)

    We show that if we invoke e + - × 2R symmetry, one combination of right-handed neutrino states remains massless which can be interpreted as a sterile ... Author Affiliations. Biswajoy Brahmachari1 2 Sandhya Choubey3 Rabindra N Mohapatra4. Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 ...

  17. Characterisation and modelling of the microstructural and mechanical evolution of a steam turbine rotor steel

    International Nuclear Information System (INIS)

    Mayer, T.

    2012-01-01

    This dissertation deals with the effective mechanical analysis of steam turbine parts which is not only required for the reliable and safe use of newly built steam turbines, but also for the remaining life assessment of components that have been exposed to service duty over long periods of time. This Thesis aims to develop a physically motivated evolutionary constitutive model for a low-alloy bainitic 2CrMoNiWV (23CrMoNiWV8-8) steam turbine rotor steels. A comprehensive experimental characterisation is performed concerning the mechanical and microstructural evolution of 2CrMoNiWV as subjected to low cycle fatigue (LCF) deformation at elevated temperatures, at different strain rates and for various strain amplitudes. This cyclic plastic deformation causes the rearrangement of dislocations in the microstructure of the steels used for such rotor applications. Symmetric, strain controlled LCF experiments have been carried out in the Laboratory of the High Temperature Integrity Group at the Swiss Federal Laboratories for Materials Science and Technology EMPA. These include mechanical tests in the temperature range between 20 °C to 600 °C at strain rates of 0.001%/s to 1.0%/s and strain amplitudes of ±0.25% to ±1.0%. The LCF experiments reported on comprehensively characterise the temperature, strain rate and strain amplitude dependent cyclic elastic-plastic behaviour of 2CrMoNiWV. Both complete single-specimen endurance tests and interrupted multi-specimen tests have been performed. On the basis of this experimental evidence, an evolutionary formulation of the model is further developed that excellently reproduces the strain amplitude dependent mechanical evolution of 2CrMoNiWV when subjected to LCF loading at different constant strain amplitudes but equal temperature and strain rate. The simulation of benchmark experiments introducing increasing or decreasing strain amplitude steps into the LCF deformation history provide promising results. A further important

  18. Assessment of PWR Steam Generator modelling in RELAP5/MOD2. International Agreement Report

    Energy Technology Data Exchange (ETDEWEB)

    Putney, J.M.; Preece, R.J. [National Power, Leatherhead (GB). Technology and Environment Centre

    1993-06-01

    An assessment of Steam Generator (SG) modelling in the PWR thermal-hydraulic code RELAP5/MOD2 is presented. The assessment is based on a review of code assessment calculations performed in the UK and elsewhere, detailed calculations against a series of commissioning tests carried out on the Wolf Creek PWR and analytical investigations of the phenomena involved in normal and abnormal SG operation. A number of modelling deficiencies are identified and their implications for PWR safety analysis are discussed -- including methods for compensating for the deficiencies through changes to the input deck. Consideration is also given as to whether the deficiencies will still be present in the successor code RELAP5/MOD3.

  19. Assessment of PWR Steam Generator modelling in RELAP5/MOD2

    International Nuclear Information System (INIS)

    Putney, J.M.; Preece, R.J.

    1993-06-01

    An assessment of Steam Generator (SG) modelling in the PWR thermal-hydraulic code RELAP5/MOD2 is presented. The assessment is based on a review of code assessment calculations performed in the UK and elsewhere, detailed calculations against a series of commissioning tests carried out on the Wolf Creek PWR and analytical investigations of the phenomena involved in normal and abnormal SG operation. A number of modelling deficiencies are identified and their implications for PWR safety analysis are discussed -- including methods for compensating for the deficiencies through changes to the input deck. Consideration is also given as to whether the deficiencies will still be present in the successor code RELAP5/MOD3

  20. Comprehensive Modeling of U-Tube Steam Generators Using Extreme Learning Machines

    Science.gov (United States)

    Beyhan, Selami; Kavaklioglu, Kadir

    2015-10-01

    This paper proposes artificial neural network and fuzzy system-based extreme learning machines (ELM) for offline and online modeling of U-tube steam generators (UTSG). Water level of UTSG systems is predicted in a one-step-ahead fashion using nonlinear autoregressive with exogenous input (NARX) topology. Modeling data are generated using a well-known and widely accepted dynamic model reported in the literature. Model performances are analyzed with different number of neurons for the neural network and with different number of rules for the fuzzy system. UTSG models are built at different reactor power levels as well as full range that corresponds to all reactor operating powers. A quantitative comparison of the models are made using the root-mean-squared error (RMSE) and the minimum-descriptive-length (MDL) criteria. Furthermore, conventional back propagation learning-based neural and fuzzy models are also designed for comparing ELMs to classical artificial models. The advantages and disadvantages of the designed models are discussed.

  1. K-FIX(GT): A computer program for modeling the expansion phase of steam explosions within complex three dimensional cavities

    International Nuclear Information System (INIS)

    Hyder, M.L.; Farawila, Y.M.; Abdel-Khalik, S.I.; Halvorson, P.J.

    1992-05-01

    In the development of the Severe Accident Analysis Program for the Savannah River production reactors, it was recognized that certain accidents have the potential for causing damaging steam explosions. The massive SRS reactor buildings are likely to withstand any imaginable steam explosion. However, reactor components and building structures including hatches, ventilation ducts, etc., could be at risk if such an explosion occurred. No tools were available to estimate the effects of such explosions on actual structures. To meet this need, the Savannah River Laboratory contracted with the Georgia Institute of Technology Research Institute for development of a computer-based calculational tool for estimating the effects of steam explosions. The goal for this study was to develop a computer code that could be used parametrically to predict the effects of various steam explosions on their surroundings. This would be able to predict whether a steam explosion of a given magnitude would be likely to fail a particular structure. This would require, of course, that the magnitude of the explosion be specified through some combination of judgment and calculation. The requested code, identified as the K-FIX(GT) code, was developed and delivered by the contractor, along with extensive documentation. The several individual reports that constitute the documentation are each being issued as a separate WSRC report. Documentation includes several model calculations, and representation of these in graphic form. This report gives detailed instructions for the use of the code, including identification of all input parameters required

  2. Thermal radiation modeling inside a degraded reactor core in presence of steam and water droplets

    International Nuclear Information System (INIS)

    Chahlafi, Miloud

    2011-01-01

    This work aims at modelling thermal radiation in a nuclear reactor, in the course of a severe accident leading to its degradation. Because the reactor coolant is water, radiative heat transfer occurs in presence of steam and water droplets. The 3D geometry of a fuel bundle with 21 damaged rods has been characterized from γ-tomography images. The degradation of the rods has been simulated in the experimental small-scale facility PHEBUS. The homogenized radiative properties of the considered configurations with a transparent fluid phase have been completely characterized by both the extinction cumulated distribution function G ext and the scattering phase functions p. G ext strongly differs from the exponential function associated with the Beer law and p strongly depends on both the incidence and the scattering directions. By using the radiative transfer equation generalized for non Beerian porous media by Taine et al. the radiative conductivity tensor has been first determined with a transparent fluid phase, by a numerical perturbation method. Only the diagonal radial and axial components of this tensor are not equal to zero. They have been fitted by a simple law only depending on the porosity, the specific area and the wall absorptivity. In a second step, a radiative transfer equation based on three temperatures is established. This model takes into account a semi transparent fluid phase by coupling the radiative properties of fluid and solid phases. The radiative properties of water steam and droplets are calculated respectively with the CK approach and Mie theory, in typical thermal hydraulics conditions of reactor accidents. The radiative fluxes verify the Fourier law and are characterized by radiative coupled conductivity tensors associated with the temperatures of each phase. The radiative powers exchanged between phases per unit volume are also calculated from this model. (author)

  3. Sterilization of heparinized cuprophan hemodialysis membranes

    NARCIS (Netherlands)

    ten Hoopen, Hermina W.M.; Hinrichs, W.L.J.; Hinrichs, W.L.J.; Engbers, G.H.M.; Feijen, Jan

    1996-01-01

    The effects of sterilization of dry heparinized Cuprophan hemodialysis membranes by means of ethylene oxide (EtO) exposure, gamma irradiation, or steam on the anticoagulant activity and chemical characteristics of immobilized heparin and the permeability of the membrane were investigated.

  4. Steam sterilization of previously-assembled laparoscopic instruments Esterilización por vapor de los instrumentos laparoscópicos previamente armados Esterilização pelo vapor dos instrumentos laparoscópicos previamente montados

    Directory of Open Access Journals (Sweden)

    Tamara Carolina de Camargo

    2008-01-01

    Full Text Available Video-laparoscopy represents one of the greatest surgical advances in the recent past. Reprocessable laparoscopic instruments are complex devices that, if completely disassembled for sterilization, would cause problems for the surgical teams at the moment of their use in the surgery. The method of choice for the sterilization of this equipment is saturated steam under pressure. The goal of this review was to describe the state-of-the-art in the search for safe results in autoclaving the previously-assembled reprocessable laparoscopic instruments, since they are difficult to assemble at the moment of surgery. The PUBMED database was consulted, using controlled and free keywords, as well as their combinations, without time or language restrictions. The study investigating the exact issue of this research found contamination in both assembled (1/24 and disassembled (1/30 instruments, demonstrating equivalent risks. In view of the results and considering the lack of studies, a new experimental laboratory study is recommended, using a contamination challenge.El video-laparoscopía representa uno de los mayores avances en el área de la cirugía en los últimos tiempos. Los instrumentos laparoscópicos reprocesables son artículos complejos, que si son esterilizados totalmente desarmados ocasionan trastornos a los equipos quirúrgicos en el momento de su utilización en el campo operatorio. El método de elección para la esterilización de esos instrumentos es el vapor saturado bajo presión. El objetivo de esta revisión fue describir el estado del arte en búsqueda de los resultados de la seguridad en el autoclavado del instrumental laparoscópico reprocesable, previamente armado, teniendo presente las dificultades de su montaje en el momento de la cirugía. Se consultó la base de datos PUBMED, usando vocablos controlados, libres y la combinación de ambos, sin restricción de tiempo e idioma. Fueron localizados apenas dos artículos que

  5. Cold start-up condition model for heat recovery steam generators

    International Nuclear Information System (INIS)

    Sindareh-Esfahani, Peyman; Habibi-Siyahposh, Ehsan; Saffar-Avval, Majid; Ghaffari, Ali; Bakhtiari-Nejad, Firooz

    2014-01-01

    A dynamic modeling of Heat Recovery Steam Generator (HRSG) during cold start-up operation in Combined Cycle Power Plant (CCPP) is introduced. In order to characterize the essential dynamic behavior of the HRSG during cold start-up; Dynamic equations of all HRSG's components are developed based on energy and mass balances. To describe precisely the operation of HRSG; a method based on nonlinear estimated functions for thermodynamic properties is applied to estimate the model parameters. Model parameters are evaluated by a designed algorithm based on Genetic Algorithm (GA). A wide set of experimental data is used to validate HRSG model during cold start-up operation. The simulation results show the reliability and validity of the developed model for cold start-up operation. - Highlights: •Presenting a mathematical model for HRSGs cold start-up based on energy and mass balances. •A designed parameter identification algorithm based on GA is presented. •Application of experimental data in order to model and validate simulation results

  6. Interdisciplinary semantic model for managing the design of a steam-assisted gravity drainage tooling system

    Directory of Open Access Journals (Sweden)

    Michael Leitch

    2018-01-01

    Full Text Available Complex engineering systems often require extensive coordination between different expert areas in order to avoid costly design iterations and rework. Cyber-physics system (CPS engineering methods could provide valuable insights to help model these interactions and optimize the design of such systems. In this work, steam assisted gravity drainage (SAGD, a complex oil extraction process that requires deep understanding of several physical-chemical phenomena, is examined whereby the complexities and interdependencies of the system are explored. Based on an established unified feature modeling scheme, a software modeling framework is proposed to manage the design process of the production tools used for SAGD oil extraction. Applying CPS methods to unify complex phenomenon and engineering models, the proposed CPS model combines effective simulation with embedded knowledge of completion tooling design in order to optimize reservoir performance. The system design is expressed using graphical diagrams of the unified modelling language (UML convention. To demonstrate the capability of this system, a distributed research group is described, and their activities coordinated using the described CPS model.

  7. Biomass Steam Gasification with In-Situ CO2 Capture for Enriched Hydrogen Gas Production: A Reaction Kinetics Modelling Approach

    Directory of Open Access Journals (Sweden)

    Mohamed Ibrahim Abdul Mutalib

    2010-08-01

    Full Text Available Due to energy and environmental issues, hydrogen has become a more attractive clean fuel. Furthermore, there is high interest in producing hydrogen from biomass with a view to sustainability. The thermochemical process for hydrogen production, i.e. gasification, is the focus of this work. This paper discusses the mathematical modeling of hydrogen production process via biomass steam gasification with calcium oxide as sorbent in a gasifier. A modelling framework consisting of kinetics models for char gasification, methanation, Boudouard, methane reforming, water gas shift and carbonation reactions to represent the gasification and CO2 adsorption in the gasifier, is developed and implemented in MATLAB. The scope of the work includes an investigation of the influence of the temperature, steam/biomass ratio and sorbent/biomass ratio on the amount of hydrogen produced, product gas compositions and carbon conversion. The importance of different reactions involved in the process is also discussed. It is observed that hydrogen production and carbon conversion increase with increasing temperature and steam/biomass ratio. The model predicts a maximum hydrogen mole fraction in the product gas of 0.81 occurring at 950 K, steam/biomass ratio of 3.0 and sorbent/biomass ratio of 1.0. In addition, at sorbent/biomass ratio of 1.52, purity of H2 can be increased to 0.98 mole fraction with all CO2 present in the system adsorbed.

  8. Modelling Aedes aegypti mosquito control via transgenic and sterile insect techniques: Endemics and emerging outbreaks

    KAUST Repository

    Seirin Lee, S.

    2013-08-01

    The invasion of pest insects often changes or destroys a native ecosystem, and can result in food shortages and disease endemics. Issues such as the environmental effects of chemical control methods, the economic burden of maintaining control strategies and the risk of pest resistance still remain, and mosquito-borne diseases such as malaria and dengue fever prevail in many countries, infecting over 100 million worldwide in 2010. One environmentally friendly method for mosquito control is the Sterile Insect Technique (SIT). This species-specific method of insect control relies on the mass rearing, sterilization and release of large numbers of sterile insects. An alternative transgenic method is the Release of Insects carrying a Dominant Lethal (RIDL). Our objective is to consider contrasting control strategies for two invasive scenarios via SIT and RIDL: an endemic case and an emerging outbreak. We investigate how the release rate and size of release region influence both the potential for control success and the resources needed to achieve it, under a range of conditions and control strategies, and we discuss advantageous strategies with respect to reducing the release resources and strategy costs (in terms of control mosquito numbers) required to achieve complete eradication of wild-type mosquitoes. © 2013 Elsevier Ltd.

  9. Steam drums

    International Nuclear Information System (INIS)

    Crowder, R.

    1978-01-01

    Steam drums are described that are suitable for use in steam generating heavy water reactor power stations. They receive a steam/water mixture via riser headers from the reactor core and provide by means of separators and driers steam with typically 0.5% moisture content for driving turbines. The drums are constructed as prestressed concrete pressure vessels in which the failure of one or a few of the prestressing elements does not significantly affect the overall strength of the structure. The concrete also acts as a radiation shield. (U.K.)

  10. Slow Steaming in Maritime Transportation: Fundamentals, Trade-offs, and Decision Models

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.; Kontovas, Christos A.

    2015-01-01

    Slow steaming is being practised in many sectors of the shipping industry. It is induced principally by depressed shipping markets and/or high fuel prices. In recent years the environmental dimension of slow steaming has also become important, as ship emissions are directly proportional to fuel b...

  11. Coalescence model of two collinear cracks existing in steam generator tubes

    International Nuclear Information System (INIS)

    Moon, S.-I.; Chang, Y.-S.; Kim, Y.-J.; Park, Y.-W.; Song, M.-H.; Choi, Y.-H.; Lee, J.-H.

    2005-01-01

    The 40% of wall thickness criterion has been used as a plugging rule of steam generator tubes but it can be applicable just to a single-cracked tubes. In the previous studies preformed by the authors, a total of 10 local failure prediction models were introduced to estimate the coalescence load of two adjacent collinear through-wall cracks existing in thin plates, and the reaction force model and plastic zone contact model were selected as optimum models among them. The objective of this study is to verify the applicability of the proposed optimum local failure prediction models to the tubes with two collinear through-wall cracks. For this, a series of plastic collapse tests and finite element analyses were carried out using the tubes containing two collinear through-wall cracks. It has been shown that the proposed optimum failure models can predict the local failure behavior of two collinear through-wall cracks existing in tubes well. And a coalescence evaluation diagram was developed which can be used to determine whether the adjacent cracks detected by NED coalsece or not. (authors)

  12. 99mTc-ciprofloxacin imaging in infectious and sterile inflammation in rat model

    International Nuclear Information System (INIS)

    Shin, Jung Woo; Ryu, Jin Sook; Oh, Seung Jun; Choen, Jun Hong; Moon, Dae Hyuk; Lee, Hee Kyung

    1999-01-01

    99m Tc-Ciprofloxacin is a potentially specific agent for bacterial infection. The aim of this study was to find out whether 99m Tc-Ciprofloxacin accumulation can differentiate bacterial infectious inflammation from nonbacterial sterile inflammation. 99m Tc-Ciprofloxacin was synthesized with 99m Tc 20 mCi, ciprofloxacine 2 mg, formamidine sulphinic acid 1 mg, and 15 sec heating in microwave. For induction of infectious or sterile inflammation in SD rats, 2 x 10 8 of S. aureus in 0.2ml (group1, n=9) or 0.2 ml of terpentine oil (group 2, n=10) were injected to thigh muscle. Three days later, 99m Tc-Ciprofloxacin images were obtained at 4 hrs after iv injection of 37MBq of 99m Tc-Ciprofloxacin. Immediately after imaging, rats were sacrificed and dissected to obtain %ID/g of normal organs and inflammatory lesions. For histopathologic evaluation, tissue specimens from the inflammatory lesions were obtained. The induction of infection/inflammation produced marked swelling of thighs in both groups. 99m Tc-Ciprofloxacin imaging of both groups showed increased uptake, but target to background uptake ratio in group 1 was significantly higher than group 2 (3.70±0.5 vs 2.18±0.3, p 99m Tc-Ciprofloxacin in liver, slpeen, kidney were 6.1±0.45, 5.1±0.42, 3.42±0.2%ID/g, respectively, and inflammatory lesion in group 1 and group 2 were 0.42±0.09 and 0.24±0.02%ID/g, respectively. Both lesion to normal muscle activity ratio and lesion to blood activity ratio of 99m Tc-Ciprofloxacin in group 1 were significantly higher than group 2 (5.29±2.3 vs 1.69±0.2, 1.45±0.47 vs 0.93±0.2, p 99m Tc-Ciprofloxacin uptake is significantly higher in bacterial infectious inflammation than sterile inflammation. However, further studies and cautious clinical application are needed for differentiating infectious from sterile inflammation using 99m Tc-Ciprofloxacin imaging, because there is still significant degree of 99m Tc-Ciprofloxacin accumulation in sterile inflammation

  13. The development and application of overheating failure model of FBR steam generator tubes. 2

    International Nuclear Information System (INIS)

    Miyake, Osamu; Hamada, Hirotsugu; Tanabe, Hiromi

    2001-11-01

    The JNC technical report 'The Development and Application of Overheating Failure Model of FBR Steam Generator Tubes' summarized the assessment method and its application for the overheating tube failure in an event of sodium-water reaction accident of fast breeder reactor's steam generators (SGs). This report describes the following items studied after the publication of the above technical report. 1. On the basis of the SWAT-3 experimental data, realistic local heating conditions (reaction zone temperature and related heat transfer conditions) for the sodium-water reaction were proposed. New correlations are cosine-shaped temperature profiles with 1,170 C maximum for the 100% and 40% Monju operating conditions, and those with 1,110 C maximum for the 10% condition. 2. For the cooling effects inside of target tubes, LWR's studies of critical heat flux (CHF) and post-CHF heat transfer correlations have been examined and considered in the assessment. The revised assessment adopts the Katto's correlation for CHF, and the Condie-Bengston IV correlation for post-CHF. 3. Other additional examination for the assessment includes treatments of the whole heating effect (other than the local reaction zone) due to the sodium-water reaction, and the temperature-dependent thermal properties of the heat transfer tube material (2.25Cr-1Mo steel). The revised overheating tube failure assessment method has been applied to the Monju SG studies. It is revealed consequently that no tube failure occurs in 100%, 40%, and 10% operating conditions when an initial leak is detected by the cover gas pressure detection system. The assessment for the SG system improved for the detection and blowdown systems shows even better safety margins against the overheating tube failure. (author)

  14. Modeling and simulation of a packed bed reactor for hydrogen by methanol steam reforming

    International Nuclear Information System (INIS)

    Aboudheir, A.; Idem, R.

    2004-01-01

    'Full text:' The performance of a catalytic packed bed tubular reactor for hydrogen production depends on mass transport characteristics and temperature distribution in the reactor. To accurately predict this performance, a rigorous numerical model has been developed based on coupled mass, energy, and momentum balance equations in cylindrical coordinates. This comprehensive model takes into account the variations of the concentration and temperature in both the axial and radial directions as well as the pressure drop along the packed reactor. Also, experimental measurements for hydrogen production were collected using a manganese-promoted co-precipitated Cu-Al catalyst for methanol-steam reforming in a micro-reactor having 10 mm i.d. and 460 mm overall length. The operating temperature ranged from 443 to 523 K and the space-time ranged from 0.1 to 2.5 kg cat h/kmol CH3OH. The simulation results were found to be in close agreement with the experimental data over the various operating conditions. This confirms the validity of both the numerical model of this work and our previous published kinetics models for this reaction system. In addition, the model formulation is applicable to handle reactions, not only for the microreactor presented in this work, but also, for other laboratory size and industrial scale processes for hydrogen production by hydrocarbon reformation. (author)

  15. Study and modelling of an industrial plant for hydrogen production by High Temperature Steam Electrolysis

    International Nuclear Information System (INIS)

    Bertier, L.

    2012-01-01

    HTSE field (High Temperature Steam Electrolysis) is moving from the research phase to development phase. It's now necessary to prove and to possibly improve the technology competitiveness. Therefore we need a tool able to allow communication between hydrogen producers and electrolysis cell stack designers. Designers seek where their efforts have to focus, for example by searching what are the operating best conditions for HTSE (voltage, temperature). On the contrary, the producer wants to choose the most suitable stack for its needs and under the best conditions: hydrogen has to be produced at the lowest price. Two main constraints have been identified to reach this objective: the tool has to be inserted into a process simulation software and needs to be representative of the cell and stack used technology. These constraints are antagonistic. Making an object model in a process simulation usually involves a highly simplified representation of it. To meet these constraints, we have built a model chain starting from the electrode models and leading to a representative model of the HTSE technology used process. Work and added value of this thesis mainly concern a global and local energy optimization approach. Our model allows at each scale an appropriate analysis of the main phenomena occurring in each object and a quantification of the energy and economic impacts of the technology used. This approach leads to a tool able to achieve the technical and economic optimization of a HTSE production unit. (author) [fr

  16. Steam 80 steam generator instrumentation

    International Nuclear Information System (INIS)

    Carson, W.H.; Harris, H.H.

    1980-01-01

    This paper describes two special instrumentation packages in an integral economizer (preheater) steam generator of one of the first System 80 plants scheduled to go into commercial operation. The purpose of the instrumentation is to obtain accurate operating information from regions of the secondary side of the steam generator inaccessible to normal plant instrumentation. In addition to verification of the System 80 steam generator design predictions, the data obtained will assist in verification of steam generator thermal/hydraulic computer codes developed for generic use in the industry

  17. Phenomenological modeling of eddy current signals with a view to characterizing steam generator tube flaws

    International Nuclear Information System (INIS)

    La, R.

    1997-01-01

    This work deals with the eddy current non-destructive test ing. Its long-term goal is to design an 'inverse model' for evaluating the geometry an d the dimensions of steam generator tube flaws from eddy current signals. The approach we adopted requires the preliminary knowledge of a 'forward model' that estimates the eddy current signal knowing the geometry and the dimensions of the flaws. A quasi-exhaustive study of the existing forward models showed their inadequacy to solve the inverse problem. Hence, we proposed to build a general forward model, appropriate to the inversion. Using a parametric approach, this model is phenomenological, i.e. it is based on observations made from results of a finite element code. For each position of the coil, the proposed forward model fist discretized the eddy current distribution into 'tubes of current'. A parametric description of the shape of these tubes is given according the system constituted of the coil and the tubes of current as a 'multi-transformer', their current signal, can then be deduced. The model was validated in the case of an axisymmetric configuration. Comparisons with both analytical and numerical models showed very good agreements. Then, the proposed model was applied to a three-dimensional configuration. Comparisons with experimental results are sufficiently conclusive to validate the approach to the construction of the phenomenological model. However, before envisaging the inverse problem, the computation time, still too long, ought to be reduced and the parametric description needs to be generalized to other three-dimensional configurations. (author)

  18. Stochastic modeling of inspection uncertainties and applications to pitting flaws in steam generator tubes

    International Nuclear Information System (INIS)

    Mao, D.; Yuan, X.-X.; Pandey, M.D.

    2009-01-01

    Steam generators (SG) are a major pressure retaining component of great safety significance in nuclear power plants. Due to various manufacturing, operation and maintenance activities, as well as material interaction with the surrounding chemical environment, the SG tubes have been subject to a number of degradation modes. Among them, the under-deposit pitting corrosion at outside surfaces of the SG tubes just on top of the tubesheet support plates has had a serious impact on the integrity of the SG tubes. This paper presents an advanced probabilistic model of pitting corrosion characterizing the inherent randomness of the pitting process and measurement uncertainties of the in-service inspection (ISI) data obtained from eddy current (EC) inspections. A Bayesian method based on Markov Chain Monte Carlo (MCMC) simulation is developed for estimating the model parameters. The proposed model is able to predict the actual pit number, the actual pit depth as well as the maximum pit depth, which is the main interest of the pitting corrosion model. (author)

  19. Numerical comparison between a reference and simplified two-phase flow models as applied to steam generator dynamics

    International Nuclear Information System (INIS)

    Dupont, J.-F.; Sarlos, G.; Le Febve, D.M.; Suter, P.

    1980-01-01

    An important issue in two-phase flow dynamics modelling remains to know how and how much as well as for what kind of dynamical conditions a computer model can be simplified to save computing time while keeping enough accuracy. In order to get insight in this issue, numerical experiments have been performed to compare computed results of a reference model with those of various simplified models. These comparisons are devoted to the transient behaviour of a steam generator of counter flow type with liquid sodium as primary heating fluid. The investigated transients are induced by rapid or slow variations (steps and ramps) of the boundary conditions, i.e. steam pressure, feedwater flow rate, inlet temperatures, etc. This paper presents a review of results and conclusions. Numerical rules are given on the validity of the investigated simplifications, which should facilitate the selection of an adequate model for a given dynamical situation. (author)

  20. Steam condenser

    International Nuclear Information System (INIS)

    Masuda, Fujio

    1980-01-01

    Purpose: To enable safe steam condensation by providing steam condensation blades at the end of a pipe. Constitution: When high temperature high pressure steam flows into a vent pipe having an opening under water in a pool or an exhaust pipe or the like for a main steam eacape safety valve, non-condensable gas filled beforehand in the steam exhaust pipe is compressed, and discharged into the water in the pool. The non-condensable gas thus discharged from the steam exhaust pipe is introduced into the interior of the hollow steam condensing blades, is then suitably expanded, and thereafter exhausted from a number of exhaust holes into the water in the pool. In this manner, the non-condensable gas thus discharged is not directly introduced into the water in the pool, but is suitable expanded in the space of the steam condensing blades to suppress extreme over-compression and over-expansion of the gas so as to prevent unstable pressure vibration. (Yoshihara, H.)

  1. Priming of innate antimycobacterial immunity by heat-killedListeria monocytogenesinduces sterilizing response in the adult zebrafish tuberculosis model.

    Science.gov (United States)

    Luukinen, Hanna; Hammarén, Milka Marjut; Vanha-Aho, Leena-Maija; Svorjova, Aleksandra; Kantanen, Laura; Järvinen, Sampsa; Luukinen, Bruno Vincent; Dufour, Eric; Rämet, Mika; Hytönen, Vesa Pekka; Parikka, Mataleena

    2018-01-29

    Mycobacterium tuberculosis remains one of the most problematic infectious agents, owing to its highly developed mechanisms to evade host immune responses combined with the increasing emergence of antibiotic resistance. Host-directed therapies aiming to optimize immune responses to improve bacterial eradication or to limit excessive inflammation are a new strategy for the treatment of tuberculosis. In this study, we have established a zebrafish- Mycobacterium marinum natural host-pathogen model system to study induced protective immune responses in mycobacterial infection. We show that priming adult zebrafish with heat-killed Listeria monocytogenes (HKLm) at 1 day prior to M. marinum infection leads to significantly decreased mycobacterial loads in the infected zebrafish. Using rag1 -/- fish, we show that the protective immunity conferred by HKLm priming can be induced through innate immunity alone. At 24 h post-infection, HKLm priming leads to a significant increase in the expression levels of macrophage-expressed gene 1 ( mpeg1 ), tumor necrosis factor α ( tnfa ) and nitric oxide synthase 2b ( nos2b ), whereas superoxide dismutase 2 ( sod2 ) expression is downregulated, implying that HKLm priming increases the number of macrophages and boosts intracellular killing mechanisms. The protective effects of HKLm are abolished when the injected material is pretreated with nucleases or proteinase K. Importantly, HKLm priming significantly increases the frequency of clearance of M. marinum infection by evoking sterilizing immunity (25 vs 3.7%, P =0.0021). In this study, immune priming is successfully used to induce sterilizing immunity against mycobacterial infection. This model provides a promising new platform for elucidating the mechanisms underlying sterilizing immunity and to develop host-directed treatment or prevention strategies against tuberculosis.This article has an associated First Person interview with the first author of the paper. © 2018. Published by

  2. Study and modelling of the escalation phase of a steam explosion

    International Nuclear Information System (INIS)

    Leclerc, Eric

    2000-01-01

    In Severe Accident studies for PWR, large amount of molten corium may be poured into water. There is then a risk of Steam Explosion. After the premixing sequence in which the melt is more or less dispersed into water, a fine fragmentation process may start which can lead to an escalation. Such an event is generally triggered by the destabilization of the vapour film surrounding the hot melt droplets. In this thesis, an attempt to describe all the successive processes leading to this fine fragmentation is presented. First a critical analysis of previous models is performed, allowing to propose a new sequence of events. As in the previous models, the film destabilization leads to the growth of cold liquids peaks induced by Rayleigh Taylor instability. As these peaks have a smaller density than the drop, they do not penetrate into the hot drop. At the cold liquid-hot liquid contacts, transient heat transfer leads to the explosive boiling of a small amount of coolant. The generated local pressurization deform the hot melt interface. This can produce fine fragments from the filaments issued from the melt. Some of them may reach the vapour-coolant interface where intense and rapid vaporization occurs. A large bubble then develops and a new fragmentation sequence may again appear at the bubble collapse. The present model is support by experimental results. (author) [fr

  3. Thermalizing Sterile Neutrino Dark Matter

    Science.gov (United States)

    Hansen, Rasmus S. L.; Vogl, Stefan

    2017-12-01

    Sterile neutrinos produced through oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. We analyze the impact of new interactions on the evolution of keV sterile neutrino dark matter in the early Universe. Based on general considerations we find a mechanism which thermalizes the sterile neutrinos after an initial production by oscillations. The thermalization of sterile neutrinos is accompanied by dark entropy production which increases the yield of dark matter and leads to a lower characteristic momentum. This resolves the growing tensions with structure formation and x-ray observations and even revives simple nonresonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy and entropy conservation describes the mechanism well.

  4. Thermalizing Sterile Neutrino Dark Matter.

    Science.gov (United States)

    Hansen, Rasmus S L; Vogl, Stefan

    2017-12-22

    Sterile neutrinos produced through oscillations are a well motivated dark matter candidate, but recent constraints from observations have ruled out most of the parameter space. We analyze the impact of new interactions on the evolution of keV sterile neutrino dark matter in the early Universe. Based on general considerations we find a mechanism which thermalizes the sterile neutrinos after an initial production by oscillations. The thermalization of sterile neutrinos is accompanied by dark entropy production which increases the yield of dark matter and leads to a lower characteristic momentum. This resolves the growing tensions with structure formation and x-ray observations and even revives simple nonresonant production as a viable way to produce sterile neutrino dark matter. We investigate the parameters required for the realization of the thermalization mechanism in a representative model and find that a simple estimate based on energy and entropy conservation describes the mechanism well.

  5. Numerical discretization analysis of a HTR steam generator model for the thermal-hydraulics code trace

    Directory of Open Access Journals (Sweden)

    Esch Markus

    2014-01-01

    Full Text Available For future high temperature reactor projects, e. g., for electricity production or nuclear process heat applications, the steam generator is a crucial component. A typical design is a helical coil steam generator consisting of several tubes connected in parallel forming cylinders of different diameters. This type of steam generator was a significant component used at the thorium high temperature reactor. In the work presented the temperature profile is being analyzed by the nodal thermal hydraulics code TRACE for the thorium high temperature reactor steam generator. The influence of the nodalization is being investigated within the scope of this study and compared to experimental results from the past. The results of the standard TRACE code are compared to results using a modified Nusselt number for the primary side. The implemented heat transfer correlation was developed within the past German HTR program. This study shows that both TRACE versions are stable and provides a discussion of the nodalization requirements.

  6. Modelling and exergoeconomic-environmental analysis of combined cycle power generation system using flameless burner for steam generation

    International Nuclear Information System (INIS)

    Hosseini, Seyed Ehsan; Barzegaravval, Hasan; Ganjehkaviri, Abdolsaeid; Wahid, Mazlan Abdul; Mohd Jaafar, M.N.

    2017-01-01

    Highlights: • Using flameless burner as a supplementary firing system after gas turbine is modeled. • Thermodynamic, economic and environmental analyses of this model are performed. • Efficiency of the plant increases about 6% and CO 2 emission decreases up to 5.63% in this design. • Available exergy for work production in both gas cycle and steam cycle increases in this model. - Abstract: To have an optimum condition for the performance of a combined cycle power generation, using supplementary firing system after gas turbine was investigated by various researchers. Since the temperature of turbine exhaust is higher than auto-ignition temperature of the fuel in optimum condition, using flameless burner is modelled in this paper. Flameless burner is installed between gas turbine cycle and Rankine cycle of a combined cycle power plant which one end is connected to the outlet of gas turbine (as primary combustion oxidizer) and the other end opened to the heat recovery steam generator. Then, the exergoeconomic-environmental analysis of the proposed model is evaluated. Results demonstrate that efficiency of the combined cycle power plant increases about 6% and CO 2 emission reduces up to 5.63% in this proposed model. It is found that the variation in the cost is less than 1% due to the fact that a cost constraint is implemented to be equal or lower than the design point cost. Moreover, exergy of flow gases increases in all points except in heat recovery steam generator. Hence, available exergy for work production in both gas cycle and steam cycle will increase in new model.

  7. The role of CFD combustion modelling in hydrogen safety management – VI: Validation for slow deflagration in homogeneous hydrogen-air-steam experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cutrono Rakhimov, A., E-mail: cutrono@nrg.eu [Nuclear Research and Consultancy Group (NRG), Westerduinweg 3, 1755 ZG Petten (Netherlands); Visser, D.C., E-mail: visser@nrg.eu [Nuclear Research and Consultancy Group (NRG), Westerduinweg 3, 1755 ZG Petten (Netherlands); Holler, T., E-mail: tadej.holler@ijs.si [Jožef Stefan Institute (JSI), Jamova cesta 39, 1000 Ljubljana (Slovenia); Komen, E.M.J., E-mail: komen@nrg.eu [Nuclear Research and Consultancy Group (NRG), Westerduinweg 3, 1755 ZG Petten (Netherlands)

    2017-01-15

    Highlights: • Deflagration of hydrogen-air-steam homogeneous mixtures is modeled in a medium-scale containment. • Adaptive mesh refinement is applied on flame front positions. • Steam effect influence on combustion modeling capabilities is investigated. • Mean pressure rise is predicted with 18% under-prediction when steam is involved. • Peak pressure is evaluated with 5% accuracy when steam is involved. - Abstract: Large quantities of hydrogen can be generated during a severe accident in a water-cooled nuclear reactor. When released in the containment, the hydrogen can create a potential deflagration risk. The dynamic pressure loads resulting from hydrogen combustion can be detrimental to the structural integrity of the reactor. Therefore, accurate prediction of these pressure loads is an important safety issue. In previous papers, we validated a Computational Fluid Dynamics (CFD) based method to determine the pressure loads from a fast deflagration. The combustion model applied in the CFD method is based on the Turbulent Flame Speed Closure (TFC). In our last paper, we presented the extension of this combustion model, Extended Turbulent Flame Speed Closure (ETFC), and its validation against hydrogen deflagration experiments in the slow deflagration regime. During a severe accident, cooling water will enter the containment as steam. Therefore, the effect of steam on hydrogen deflagration is important to capture in a CFD model. The primary objectives of the present paper are to further validate the TFC and ETFC combustion models, and investigate their capability to predict the effect of steam. The peak pressures, the trends of the flame velocity, and the pressure rise with an increase in the initial steam dilution are captured reasonably well by both combustion models. In addition, the ETFC model appeared to be more robust to mesh resolution changes. The mean pressure rise is evaluated with 18% under-prediction and the peak pressure is evaluated with 5

  8. Current systems of sterilization in the Philippines in both government and private hospitals

    International Nuclear Information System (INIS)

    Lim, L.E.

    1996-01-01

    In the Philippines, there are 1,700 registered hospitals, both private and government. There are 80,000 beds. The systems of sterilization are mainly using steam or to use ethylene oxide sterilization. Gamma ray sterilization is purely on experimental basis and very limited scale for industrial products. The author will trace the history of sterilization, practised since a century ago and trace back to the present system of sterilization. The principles applied, precautions and limitations or advantages of the different systems will be discussed particularly steam sterilization and ethylene oxide. Other forms of sterilization either chemical or physical will be discussed in passing. Experience in gamma ray sterilization in Japan and Australia will be presented when available data are obtained, to encourage local investors to engage in such venture. Philippines has been left behind by our neighbors. (author)

  9. Modeling of the steam hydrolysis in a two-step process for hydrogen production by solar concentrated energy

    Science.gov (United States)

    Valle-Hernández, Julio; Romero-Paredes, Hernando; Pacheco-Reyes, Alejandro

    2017-06-01

    In this paper the simulation of the steam hydrolysis for hydrogen production through the decomposition of cerium oxide is presented. The thermochemical cycle for hydrogen production consists of the endothermic reduction of CeO2 to lower-valence cerium oxide, at high temperature, where concentrated solar energy is used as a source of heat; and of the subsequent steam hydrolysis of the resulting cerium oxide to produce hydrogen. The modeling of endothermic reduction step was presented at the Solar Paces 2015. This work shows the modeling of the exothermic step; the hydrolysis of the cerium oxide (III) to form H2 and the corresponding initial cerium oxide made at lower temperature inside the solar reactor. For this model, three sections of the pipe where the reaction occurs were considered; the steam water inlet, the porous medium and the hydrogen outlet produced. The mathematical model describes the fluid mechanics; mass and energy transfer occurring therein inside the tungsten pipe. Thermochemical process model was simulated in CFD. The results show a temperature distribution in the solar reaction pipe and allow obtaining the fluid dynamics and the heat transfer within the pipe. This work is part of the project "Solar Fuels and Industrial Processes" from the Mexican Center for Innovation in Solar Energy (CEMIE-Sol).

  10. A Differential-Algebraic Model for the Once-Through Steam Generator of MHTGR-Based Multimodular Nuclear Plants

    Directory of Open Access Journals (Sweden)

    Zhe Dong

    2015-01-01

    Full Text Available Small modular reactors (SMRs are those fission reactors whose electrical output power is no more than 300 MWe. SMRs usually have the inherent safety feature that can be applicable to power plants of any desired power rating by applying the multimodular operation scheme. Due to its strong inherent safety feature, the modular high temperature gas-cooled reactor (MHTGR, which uses helium as coolant and graphite as moderator and structural material, is a typical SMR for building the next generation of nuclear plants (NGNPs. The once-through steam generator (OTSG is the basis of realizing the multimodular scheme, and modeling of the OTSG is meaningful to study the dynamic behavior of the multimodular plants and to design the operation and control strategy. In this paper, based upon the conservation laws of mass, energy, and momentum, a new differential-algebraic model for the OTSGs of the MHTGR-based multimodular nuclear plants is given. This newly-built model can describe the dynamic behavior of the OTSG in both the cases of providing superheated steam and generating saturated steam. Numerical simulation results show the feasibility and satisfactory performance of this model. Moreover, this model has been applied to develop the real-time simulation software for the operation and regulation features of the world first underconstructed MHTGR-based commercial nuclear plant—HTR-PM.

  11. The development and application of overheating failure model of FBR steam generator tubes. 3

    International Nuclear Information System (INIS)

    Miyake, Osamu; Hamada, Hirotsugu; Tanabe, Hiromi; Wada, Yusaku; Miyakawa, Akira; Okabe, Ayao; Nakai, Ryodai; Hiroi, Hiroshi

    2002-03-01

    The model has been developed for the assessment of the overheating tube failure in an event of sodium-water reaction accident of fast breeder reactor's steam generators (SGs). The model has been applied to the Monju SG studies. Major results obtained in the studies are as follows: 1. To evaluate the structural integrity of tube material, the strength standard for 2. 25Cr-1Mo steel was established taking account of time dependent effect based on the high temperature (700-1200degC) creep data. This standard has been validated with the tube rupture simulation test data. 2. The conditions for overheating by the high temperature reaction were determined by use of the SWAT-3 experimental data. The realistic local heating conditions (reaction zone temperature and related heat transfer conditions) for the sodium-water reaction were proposed as the cosine-shaped temperature profile. 3. For the cooling effects inside of target tubes, LWR's studies of critical heat flux (CHF) and post-CHF heat transfer correlations have been examined and considered in the model. 4. The model has been validated with experimental data obtained by SWAT-3 and LLTR. The results were satisfactory with conservatism. The PFR superheater leak event in 1987 was studied, and the cause of event and the effectiveness of the improvement after the leak event could be identified by the analysis. 5. The model has been applied to the Monju SG studies. It is revealed consequently that no tube failure occurs in 100%, 40%, and 10% water flow operating conditions when an initial leak is detected by the cover gas pressure detection system. (author)

  12. Modeling condensation on a finned tube and bundles for steam in the presence of non condensable gases

    International Nuclear Information System (INIS)

    Gambhir, U.R.; Borgohain, A.; Lingade, B.M.; Maheshwari, N.K.; Vijayan, P.K.

    2015-01-01

    Finned tube condensers can be used in advanced nuclear reactor designs as passive containment cooling systems during normal operation and accidental conditions to improve nuclear safety. For proper design of such a system, a theoretical model COFT (Condensation On Finned Tube) capable of predicting heat transfer due to condensation of steam on horizontal finned tube and tube bundles has been developed in this paper. The total thermal resistance from bulk steam and gas mixture to cooling media has been formulated. Experimental conditions concerned with smooth tubes, finned tubes, and tube bundles in the presence of noncondensables have been simulated by this model. Comparison of COFT predictions with available experimental data shows its acceptable accuracy in a wide range of conditions. Also degradation of heat transfer coefficient between finned and smooth tube bundles are compared. (author)

  13. Steam Turbines

    Science.gov (United States)

    1981-01-01

    Turbonetics Energy, Inc.'s steam turbines are used as power generating systems in the oil and gas, chemical, pharmaceuticals, metals and mining, and pulp and paper industries. The Turbonetics line benefited from use of NASA research data on radial inflow steam turbines and from company contact with personnel of Lewis Research Center, also use of Lewis-developed computer programs to determine performance characteristics of turbines.

  14. Thermoeconomic Modeling and Parametric Study of Hybrid Solid Oxide Fuel Cell â Gas Turbine â Steam Turbine Power Plants Ranging from 1.5 MWe to 10 MWe

    OpenAIRE

    Arsalis, Alexandros

    2007-01-01

    Detailed thermodynamic, kinetic, geometric, and cost models are developed, implemented, and validated for the synthesis/design and operational analysis of hybrid solid oxide fuel cell (SOFC) â gas turbine (GT) â steam turbine (ST) systems ranging in size from 1.5 MWe to 10 MWe. The fuel cell model used in this thesis is based on a tubular Siemens-Westinghouse-type SOFC, which is integrated with a gas turbine and a heat recovery steam generator (HRSG) integrated in turn with a steam turbi...

  15. Towards H2-rich gas production from unmixed steam reforming of methane: Thermodynamic modeling

    Science.gov (United States)

    Lima da Silva, Aline; Müller, Iduvirges Lourdes

    2011-10-01

    In this work, the Gibbs energy minimization method is applied to investigate the unmixed steam reforming (USR) of methane to generate hydrogen for fuel cell application. The USR process is an advanced reforming technology that relies on the use of separate air and fuel/steam feeds to create a cyclic process. Under air flow (first half of the cycle), a bed of Ni-based material is oxidized, providing the heat necessary for the steam reforming that occurs subsequently during fuel/steam feed stage (second half of the cycle). In the presence of CaO sorbent, high purity hydrogen can be produced in a single reactor. In the first part of this work, it is demonstrated that thermodynamic predictions are consistent with experimental results from USR isothermal tests under fuel/steam feed. From this, it is also verified that the reacted NiO to CH4 (NiOreacted/CH4) molar ratio is a very important parameter that affects the product gas composition and decreases with time. At the end of fuel/steam flow, the reforming reaction is the most important chemical mechanism, with H2 production reaching ∼75 mol%. On the other hand, at the beginning of fuel/steam feed stage, NiO reduction reactions dominate the equilibrium system, resulting in high CO2 selectivity, negative steam conversion and low concentrations of H2. In the second part of this paper, the effect of NiOreacted/CH4 molar ratio on the product gas composition and enthalpy change during fuel flow is investigated at different temperatures for inlet H2O/CH4 molar ratios in the range of 1.2-4, considering the USR process operated with and without CaO sorbent. During fuel/steam feed stage, the energy demand increases as time passes, because endothermic reforming reaction becomes increasingly important as this stage nears its end. Thus, the duration of the second half of the cycle is limited by the conditions under which auto-thermal operation can be achieved. In absence of CaO, H2 at concentrations of approximately 73 mol% can

  16. Sterile neutrino anarchy

    Science.gov (United States)

    Heeck, Julian; Rodejohann, Werner

    2013-02-01

    Lepton mixing, which requires physics beyond the Standard Model, is surprisingly compatible with a minimal, symmetryless and unbiased approach, called anarchy. This contrasts with highly involved flavor symmetry models. On the other hand, hints for light sterile neutrinos have emerged from a variety of independent experiments and observations. If confirmed, their existence would represent a groundbreaking discovery, calling for a theoretical interpretation. We discuss anarchy in the two-neutrino eV-scale seesaw framework. The distributions of mixing angles and masses according to anarchy are in agreement with global fits for the active and sterile neutrino parameters. Our minimal and economical scenario predicts the absence of neutrinoless double beta decay and one vanishing neutrino mass, and can therefore be tested in future experiments.

  17. Effects of electric current upon catalytic steam reforming of biomass gasification tar model compounds to syngas

    International Nuclear Information System (INIS)

    Tao, Jun; Lu, Qiang; Dong, Changqing; Du, Xiaoze; Dahlquist, Erik

    2015-01-01

    Highlights: • ECR technique was proposed to convert biomass gasification tar model compounds. • Electric current enhanced the reforming efficiency remarkably. • The highest toluene conversion reached 99.9%. • Ni–CeO 2 /γ-Al 2 O 3 exhibited good stability during the ECR performance. - Abstract: Electrochemical catalytic reforming (ECR) technique, known as electric current enhanced catalytic reforming technique, was proposed to convert the biomass gasification tar into syngas. In this study, Ni–CeO 2 /γ-Al 2 O 3 catalyst was prepared, and toluene was employed as the major feedstock for ECR experiments using a fixed-bed lab-scale setup where thermal electrons could be generated and provided to the catalyst. Several factors, including the electric current intensity, reaction temperature and steam/carbon (S/C) ratio, were investigated to reveal their effects on the conversion of toluene as well as the composition of the gas products. Moreover, toluene, two other tar model compounds (benzene and 1-methylnaphthalene) and real tar (tar-containing wastewater) were subjected to the long period catalytic stability tests. All the used catalysts were analyzed to determine their carbon contents. The results indicated that the presence of electric current enhanced the catalytic performance remarkably. The toluene conversion reached 99.9% under the electric current of 4 A, catalytic temperature of 800 °C and S/C ratio of 3. Stable conversion performances of benzene, 1-methylnaphthalene and tar-containing wastewater were also observed in the ECR process. H 2 and CO were the major gas products, while CO 2 and CH 4 were the minor ones. Due to the promising capability, the ECR technique deserves further investigation and application for efficient tar conversion

  18. Scaled physical model studies of the steam drive process. First annual report, September 1977-September 1978

    Energy Technology Data Exchange (ETDEWEB)

    Doscher, T M

    1980-12-01

    Scaling laws of the heat transport mechanism in steam displacement processes are developed based upon an integral energy balance equation. Unlike the differential approach adopted by previous workers, the above scaling laws do not necessitate the use of any empirical correction factor as has been done in previous scaling calculations. The results provide a complete and consistent scale-down of the energy transport behavior, which is the critical mechanism for the success of a steam injection process. In the course of the study, the scaling problems associated with relative permeability and capillary pressure are also discussed. A method which has often been used in scaling nonthermal displacement processes is applied to reduce errors due to scaling in relative permeability. Both dimensional and inspectional analyses are applied to illustrate their use in steam processes. Scale-up laws appeared in the literature and those used in this study are compared and numerical examples are given.

  19. Modelling of WWER-1000 steam generators by REALP5/MOD3.2 code

    Energy Technology Data Exchange (ETDEWEB)

    D`Auria, F.; Galassi, G.M. [Univ. of Pisa (Italy); Frogheri, M. [Univ. of Genova (Italy)

    1997-12-31

    The presentation summarises the results of best estimate calculations carried out with reference to the WWER-1000 Nuclear Power Plant, utilizing a qualified nodalization set-up for the Relap5/Mod3.2 code. The nodalization development has been based on the data of the Kozloduy Bulgarian Plant. The geometry of the steam generator imposed drastic changes in noding philosophy with respect to what is suitable for the U-tubes steam generators. For the secondary side a symmetry axis was chosen to separate (in the nodalization) the hot and the cold sides of the tubes. In this way the secondary side of the steam generators was divided into three zones: (a) the hot zone including the hot collector and the hot l/2 parts of the tubes; (b) the cold zone including the cold collector and the cold 1/2 parts of the tubes; (c) the downcomer region, where down flow is assumed. As a consequence of above in the primary side more nodes are placed on the hot side of the tubes. Steady state and transient qualification has been achieved, considering the criteria proposed at the University of Pisa, utilizing plant transient data from the Kozloduy and the Ukrainian Zaporosche Plants. The results of the application of the qualified WWER-1000 Relap5/Mod3.2 nodalization to various transients including large break LOCA, small break LOCA and steam generator tube rupture, together with a sensitivity analysis on the steam generators, are reported in the presentation. Emphasis is given to the prediction of the steam generators performances. 23 refs.

  20. Multipurpose expert-robot system model for control, diagnosis, maintenance, and repairs at the steam generators of the NPP

    International Nuclear Information System (INIS)

    Popa, I.

    1994-01-01

    The paper presents the model concept for a multipurpose expert-robot system for control, diagnosis, forecast, maintenance, and repairs at the steam generators of CANDU type nuclear power plants. The system has two separate parts: the expert system and the robot (manipulator) system. These parts compose a hierarchic structure with the expert system on the upper level. The expert system has a blackboard architecture, to which tree interfaces with the robot system, with the control system of the NPP and with the methods and techniques of control, maintenance and repairs system of the steam generator are added. Due to complex nature of its activities the expert-robot system model combines the deterministic type reasons with probabilistic, fuzzy, and neural-networks type ones. The information that enter the expert system comes from the robot system, from process, from user, and human expert. The information that enter robot system comes from the expert system, from the human operator (when connected) and from process. Control maintenance and repair operations take place by means of the robot system that can be monitored either directly by the expert system or by the human operator who follows its activity. All these activities are performed in parallel with the adequate information of the expert system directly, by the human operator, about the status parameters and, possibly, operating parameters of the steam generator components. The expert-robot system can work independently, but it can be connected and integrated in the control system of NPP, to take over and develop some of its functions. The activities concerning diagnosis and characterization of the state of steam generator components subsequent to control, as well as the forecast of their future behavior, are performed by means of the expert system. Due to these characteristics the expert-robot system can be used successfully in personnel training activities. (Author)

  1. Regenerative superheated steam turbine cycles

    Science.gov (United States)

    Fuller, L. C.; Stovall, T. K.

    1980-01-01

    PRESTO computer program was developed to analyze performance of wide range of steam turbine cycles with special attention given to regenerative superheated steam turbine cycles. It can be used to model standard turbine cycles, including such features as process steam extraction, induction and feedwater heating by external sources, peaking, and high back pressure. Expansion line efficiencies, exhaust loss, leakages, mechanical losses, and generator losses are used to calculate cycle heat rate and generator output. Program provides power engineer with flexible aid for design and analysis of steam turbine systems.

  2. Interval Female Sterilization.

    Science.gov (United States)

    Stuart, Gretchen S; Ramesh, Shanthi S

    2018-01-01

    Female sterilization is relied on by nearly one in three women aged 35-44 years in the United States. Sterilization procedures are among the most common procedures that obstetrician-gynecologists perform. The most frequent sterilization procedures include postpartum tubal ligation, laparoscopic tubal disruption or salpingectomy, and hysteroscopic tubal occlusion. The informed consent process for sterilization is crucial and requires shared decision-making between the patient and the health care provider. Counseling should include the specific risks and benefits of the specific surgical approaches. Additionally, women should be counseled on the alternatives to sterilization, including intrauterine contraceptives and subdermal contraceptive implants. Complications, including unplanned pregnancy after successful female sterilization, are rare. The objectives of this Clinical Expert Series are to describe the epidemiology of female sterilization, access to postpartum sterilization, advances in interval sterilization techniques, and clinical considerations in caring for women requesting sterilization.

  3. Steam explosion studies review

    International Nuclear Information System (INIS)

    Hwang, Moon Kyu; Kim, Hee Dong

    1999-03-01

    When a cold liquid is brought into contact with a molten material with a temperature significantly higher than the liquid boiling point, an explosive interaction due to sudden fragmentation of the melt and rapid evaporation of the liquid may take place. This phenomenon is referred to as a steam explosion or vapor explosion. Depending upon the amount of the melt and the liquid involved, the mechanical energy released during a vapor explosion can be large enough to cause serious destruction. In hypothetical severe accidents which involve fuel melt down, subsequent interactions between the molten fuel and coolant may cause steam explosion. This process has been studied by many investigators in an effort to assess the likelihood of containment failure which leads to large scale release of radioactive materials to the environment. In an effort to understand the phenomenology of steam explosion, extensive studies has been performed so far. The report presents both experimental and analytical studies on steam explosion. As for the experimental studies, both small scale tests which involve usually less than 20 g of high temperature melt and medium/large scale tests which more than 1 kg of melt is used are reviewed. For the modelling part of steam explosions, mechanistic modelling as well as thermodynamic modelling is reviewed. (author)

  4. Signature of heavy sterile neutrinos at CEPC

    Science.gov (United States)

    Liao, Wei; Wu, Xiao-Hong

    2018-03-01

    We study the production of heavy sterile neutrino N , e+e-→N ν (ν ¯), at the Circular Electron Positron Collider (CEPC) and its l j j signal in its decay to three charged fermions. We study background events for this process which are mainly events coming from W pair production. We study the production of a single heavy sterile neutrino and the sensitivity of CEPC to the mixing of the sterile neutrino with active neutrinos. We study the production of two degenerate heavy sterile neutrinos in a low energy seesaw model by taking into account the constraints on mixings of sterile neutrinos from the neutrinoless double β decay experiment and the masses and mixings of active neutrinos. We show that CEPC under proposal has a good sensitivity to the mixing of sterile neutrinos with active neutrinos for a mass of a sterile neutrino around 100 GeV.

  5. Sustainable hydrogen from bio-oil - Steam reforming of acetic acid as a model oxygenate

    NARCIS (Netherlands)

    Takanabe, K.; Aika, Ken-ichi; Seshan, Kulathuiyer; Lefferts, Leonardus

    2004-01-01

    Steam reforming of acetic acid over Pt/ZrO2 catalysts has been investigated. Pt/ZrO2 catalysts are very active, completely converting acetic acid, and give a hydrogen yield close to thermodynamic equilibrium. The catalyst deactivated by formation of oligomers which block the active sites. The

  6. Steam sterilisation's energy and water footprint.

    Science.gov (United States)

    McGain, Forbes; Moore, Graham; Black, Jim

    2017-03-01

    Objective The aim of the present study was to quantify hospital steam steriliser resource consumption to provide baseline environmental data and identify possible efficiency gains. We sought to find the amount of steriliser electricity and water used for active cycles and for idling (standby), and the relationship between the electricity and water consumption and the mass and type of items sterilised. Methods We logged a hospital steam steriliser's electricity and water meters every 5min for up to 1 year. We obtained details of all active cycles (standard 134°C and accessory or 'test' cycles), recording item masses and types. Relationships were investigated for both the weight and type of items sterilised with electricity and water consumption. Results Over 304 days there were 2173 active cycles, including 1343 standard 134°C cycles that had an average load mass of 21.2kg, with 32% of cycles water used was 1243495L (79%). Standby used 21457kWh (40%) electricity and 329200L (21%) water. Total electricity and water consumption per mass sterilised was 1.9kWhkg -1 and 58Lkg -1 , respectively. The linear regression model predicting electricity use was: kWh=15.7+ 0.14×mass (in kg; R 2 =0.58, Pwater and item type were poor. Electricity and water use fell from 3kWhkg -1 and 200Lkg -1 , respectively, for 5-kg loads to 0.5kWhkg -1 and 20Lkg -1 , respectively, for 40-kg loads. Conclusions Considerable electricity and water use occurred during standby, load mass was only moderately predictive of electricity consumption and light loads were common yet inefficient. The findings of the present study are a baseline for steam sterilisation's environmental footprint and identify areas to improve efficiencies. What is known about the topic? There is increasing interest in the environmental effects of healthcare. Life cycle assessment ('cradle to grave') provides a scientific method of analysing environmental effects. Although data of the effects of steam sterilisation are integral

  7. Neutrinos in a Sterile Throat

    CERN Document Server

    Gripaios, Ben Matthew

    2007-01-01

    We consider field-theoretic models of a warped extra dimension with multiple throats, in which fermions that are singlets of the Standard Model gauge group propagate in a separate throat from the Standard Model fields, which we call the sterile throat. The singlets mix with Standard Model fields via interactions localized on the UV brane that connects the two throats. This leads to three, light, mostly-active, Majorana neutrinos via a higher-dimensional see-saw mechanism, together with Kaluza-Klein towers of mostly-sterile neutrinos, whose scale is set by the warp factor in the sterile throat and can be very low if the throat is deep. We suggest that a model of this kind may explain all the neutrino data, reconciling the LSND result with astrophysical constraints.

  8. MECHANISTIC KINETIC MODELS FOR STEAM REFORMING OF CONCENTRATED CRUDE ETHANOL ON NI/AL2O3 CATALYST

    Directory of Open Access Journals (Sweden)

    O. A. OLAFADEHAN

    2015-05-01

    Full Text Available Mechanistic kinetic models were postulated for the catalytic steam reforming of concentrated crude ethanol on a Ni-based commercial catalyst at atmosphere pressure in the temperature range of 673-863 K, and at different catalyst weight to the crude ethanol molar flow rate ratio (in the range 0.9645-9.6451 kg catalyst h/kg mole crude ethanol in a stainless steel packed bed tubular microreactor. The models were based on Langmuir-Hinshelwood-Hougen-Watson (LHHW and Eley-Rideal (ER mechanisms. The optimization routine of Nelder-Mead simplex algorithm was used to estimate the inherent kinetic parameters in the proposed models. The selection of the best kinetic model amongst the rival kinetic models was based on physicochemical, statistical and thermodynamic scrutinies. The rate determining step for the steam reforming of concentrated crude ethanol on Ni/Al2O3 catalyst was found to be surface reaction between chemisorbed CH3O and O when hydrogen and oxygen were adsorbed as monomolecular species on the catalyst surface. Excellent agreement was obtained between the experimental rate of reaction and conversion of crude ethanol, and the simulated results, with ADD% being ±0.46.

  9. 3D model of steam generator of nuclear power plant Krsko

    International Nuclear Information System (INIS)

    Ravnikar, I.; Petelin, S.

    1995-01-01

    The Westinghouse Electric Corporation D4 steam generator design was analyzed from a thermal-hydraulic point of view using the 3D PHOENICS computer code. Void fraction, velocity and enthalpy distributions were obtained in the U-tube riser. The boundary conditions of primary side were provided by SMUP 1D code. The calculations were carried out for present operating conditions of nuclear power plant Krsko. (author)

  10. Electron electric dipole moment in mirror fermion model with electroweak scale non-sterile right-handed neutrinos

    Science.gov (United States)

    Chang, Chia-Feng; Hung, P. Q.; Nugroho, Chrisna Setyo; Tran, Van Que; Yuan, Tzu-Chiang

    2018-03-01

    The electric dipole moment of the electron is studied in detail in an extended mirror fermion model with the following unique features of (a) right-handed neutrinos are non-sterile and have masses at the electroweak scale, and (b) a horizontal symmetry of the tetrahedral group is used in the lepton and scalar sectors. We study the constraint on the parameter space of the model imposed by the latest ACME experimental limit on electron electric dipole moment. Other low energy experimental observables such as the anomalous magnetic dipole moment of the muon, charged lepton flavor violating processes like muon decays into electron plus photon and muon-to-electron conversion in titanium, gold and lead are also considered in our analysis for comparison. In addition to the well-known CP violating Dirac and Majorana phases in the neutrino mixing matrix, the dependence of additional phases of the new Yukawa couplings in the model is studied in detail for all these low energy observables.

  11. Seeking sterile neutrinos in Finslerian cosmology

    Science.gov (United States)

    Wang, Deng; Meng, Xin-He

    2017-11-01

    For the first time, to search for sterile neutrinos in the framework of Finler geometry, we constrain four cosmological models using the most stringent constraint we can provide so far. We find that the Finslerian massless sterile neutrino model can, respectively, give a better cosmological fit to data and alleviate the current H_0 tension more effectively than the other three models. For the Finslerian massless sterile neutrino model, we obtain the constraint N_eff=3.237^{+0.092}_{-0.185}, which is consistent with Δ N_eff > 0 at the 1.03σ confidence level (CL). This gives a very weak hint of massless sterile neutrinos and may imply the non-existence of massless sterile neutrinos in the Finslerian cosmological setting. For the Finslerian massive sterile neutrino model, we obtain the constraints N_eff=3.143^{+0.064}_{-0.066}, which favors Δ N_eff > 0 at the 1.47σ CL, and m_{ν , sterile}^eff sterile neutrinos are also non-existent in the Finslerian scenarios. Consequently, one may conclude that the sterile neutrinos are possibly non-existent in the Finslerian universe. Our results are compatible with the recent results of the neutrino oscillation experiments implemented by the Daya Bay and MINOS collaborations and the cosmic ray one carried out by the IceCube collaboration.

  12. Hybrid plasma-catalytic steam reforming of toluene as a biomass tar model compound over Ni/Al₂O₃ catalysts

    OpenAIRE

    Liu, SY; Mei, DH; Nahil, MA; Gadkari, S; Gu, S; Williams, PT; Tu, X

    2017-01-01

    In this study, plasma-catalytic steam reforming of toluene as a biomass tar model compound was carried out in a coaxial dielectric barrier discharge (DBD) plasma reactor. The effect of Ni/Al2O3 catalysts with different nickel loadings (5–20 wt%) on the plasma-catalytic gas cleaning process was evaluated in terms of toluene conversion, gas yield, by-products formation and energy efficiency of the plasma-catalytic process. Compared to the plasma reaction without a catalyst, the combination of D...

  13. A Novel Hybrid Approach for Numerical Modeling of the Nucleating Flow in Laval Nozzle and Transonic Steam Turbine Blades

    Directory of Open Access Journals (Sweden)

    Edris Yousefi Rad

    2017-08-01

    Full Text Available In the present research, considering the importance of desirable steam turbine design, improvement of numerical modeling of steam two-phase flows in convergent and divergent channels and the blades of transonic steam turbines has been targeted. The first novelty of this research is the innovative use of combined Convective Upstream Pressure Splitting (CUSP and scalar methods to update the flow properties at each calculation point. In other words, each property (density, temperature, pressure and velocity at each calculation point can be computed from either the CUSP or scalar method, depending on the least deviation criterion. For this reason this innovative method is named “hybrid method”. The next novelty of this research is the use of an inverse method alongside the proposed hybrid method to find the amount of the important parameter z in the CUSP method, which is herein referred to as “CUSP’s convergence parameter”. Using a relatively simple computational grid, firstly, five cases with similar conditions to those of the main cases under study in this research with available experimental data were used to obtain the value of z by the Levenberg-Marquardt inverse method. With this innovation, first, an optimum value of z = 2.667 was obtained using the inverse method and then directly used for the main cases considered in the research. Given that the aim is to investigate the two-dimensional, steady state, inviscid and adiabatic modeling of steam nucleating flows in three different nozzle and turbine blade geometries, flow simulation was performed using a relatively simple mesh and the innovative proposed hybrid method (scalar + CUSP, with the desired value of z = 2.667 . A comparison between the results of the hybrid modeling of the three main cases with experimental data showed a very good agreement, even within shock zones, including the condensation shock region, revealing the efficiency of this numerical modeling method innovation

  14. Experimental bounds on sterile neutrino mixing angles

    CERN Document Server

    Ruchayskiy, Oleg

    2012-01-01

    We derive bounds on the mixing between the left-chiral ("active") and the right-chiral ("sterile") neutrinos, provided from the combination of neutrino oscillation data and direct experimental searches for sterile neutrinos. We demonstrate that the mixing of sterile neutrinos with any flavour can be significantly suppressed, provided that the angle theta_13 is non-zero. This means that the lower bounds on sterile neutrino lifetime, coming from the negative results of direct experimental searches can be relaxed (by as much as the order of magnitude at some masses). We also demonstrate that the results of the negative searches of sterile neutrinos with PS191 and CHARM experiments are not applicable directly to the see-saw models. The reinterpretation of these results provides up to the order of magnitude stronger bounds on sterile neutrino lifetime than previously discussed in the literature. We discuss the implications of our results for the Neutrino Minimal Standard Model (the NuMSM).

  15. An analytical formulation of thermodynamic properties of dry and metastable steam suitable for computational fluid dynamics modelling of steam turbine flows

    Czech Academy of Sciences Publication Activity Database

    Hrubý, Jan; Pátek, Jaroslav; Duška, Michal

    2014-01-01

    Roč. 228, č. 2 (2014), s. 120-128 ISSN 0957-6509 R&D Projects: GA AV ČR IAA200760905; GA ČR(CZ) GAP101/11/1593; GA MŠk LG13056 Institutional support: RVO:61388998 Keywords : metastable steam * thermodynamic properties * computational fluid dynamics Subject RIV: BJ - Thermodynamics Impact factor: 0.645, year: 2014 http://pia.sagepub.com/content/228/2. toc

  16. Loss of feed flow, steam generator tube rupture and steam line break thermohydraulic experiments

    Energy Technology Data Exchange (ETDEWEB)

    Mendler, O J; Takeuchi, K; Young, M Y

    1986-10-01

    The Westinghouse Model Boiler No. 2 (MB-2) steam generator test model at the Engineering Test Facility in Tampa, Florida, was reinstrumented and modified for performing a series of tests simulating steam generator accident transients. The transients simulated were: loss of feed flow, steam generator tube rupture, and steam line break events. This document presents a description of (1) the model boiler and the associated test facility, (2) the tests performed, and (3) the analyses of the test results.

  17. Loss of feed flow, steam generator tube rupture and steam line break thermohydraulic experiments

    International Nuclear Information System (INIS)

    Mendler, O.J.; Takeuchi, K.; Young, M.Y.

    1986-10-01

    The Westinghouse Model Boiler No. 2 (MB-2) steam generator test model at the Engineering Test Facility in Tampa, Florida, was reinstrumented and modified for performing a series of tests simulating steam generator accident transients. The transients simulated were: loss of feed flow, steam generator tube rupture, and steam line break events. This document presents a description of (1) the model boiler and the associated test facility, (2) the tests performed, and (3) the analyses of the test results

  18. A flowsheet model of a coal-fired MHD/steam combined electricity generating cycle, using the access computer model

    International Nuclear Information System (INIS)

    Davison, J.E.; Eldershaw, C.E.

    1992-01-01

    This document forms the final report on a study of a coal-fired magnetohydrodynamic (MHD)/steam electric power generation system carried out by British Coal Corporation for the Commission of the European Communities. The study objective was to provide mass and energy balances and overall plant efficiency predictions for MHD to assist the Commission in their evaluation of advanced power generation technologies. In early 1990 the British Coal Corporation completed a study for the Commission in which a computer flowsheet modelling package was used to predict the performance of a conceptual air blown MHD plant. Since that study was carried out increasing emphasis has been placed on the possible need to reduce CO 2 emissions to counter the so-called greenhouse effect. Air blown MHD could greatly reduce CO 2 emissions per KWh by virtue of its high thermal efficiency. However, if even greater reductions in CO 2 emissions were required the CO 2 produced by coal combustion may have to be disposed of, for example into the deep ocean or underground caverns. To achieve this at minimum cost a concentrated CO 2 flue gas would be required. This could be achieved in an MHD plant by using a mixture of high purity oxygen and recycled CO 2 flue gas in the combustor. To assess this plant concept the European Commission awarded British Coal a contract to produce performance predictions using the access computer program

  19. AMPTRACT: an algebraic model for computing pressure tube circumferential and steam temperature transients under stratified channel coolant conditions

    International Nuclear Information System (INIS)

    Gulshani, P.; So, C.B.

    1986-10-01

    In a number of postulated accident scenarios in a CANDU reactor, some of the horizontal fuel channels are predicted to experience periods of stratified channel coolant condition which can lead to a circumferential temperature gradient around the pressure tube. To study pressure tube strain and integrity under stratified flow channel conditions, it is, necessary to determine the pressure tube circumferential temperature distribution. This paper presents an algebraic model, called AMPTRACT (Algebraic Model for Pressure Tube TRAnsient Circumferential Temperature), developed to give the transient temperature distribution in a closed form. AMPTRACT models the following modes of heat transfer: radiation from the outermost elements to the pressure tube and from the pressure to calandria tube, convection between the fuel elements and the pressure tube and superheated steam, and circumferential conduction from the exposed to submerged part of the pressure tube. An iterative procedure is used to solve the mass and energy equations in closed form for axial steam and fuel-sheath transient temperature distributions. The one-dimensional conduction equation is then solved to obtain the pressure tube circumferential transient temperature distribution in a cosine series expansion. In the limit of large times and in the absence of convection and radiation to the calandria tube, the predicted pressure tube temperature distribution reduces identically to a parabolic profile. In this limit, however, radiation cannot be ignored because the temperatures are generally high. Convection and radiation tend to flatten the parabolic distribution

  20. ISO radiation sterilization standards

    International Nuclear Information System (INIS)

    Lambert, Byron J.; Hansen, Joyce M.

    1998-01-01

    This presentation provides an overview of the current status of the ISO radiation sterilization standards. The ISO standards are voluntary standards which detail both the validation and routine control of the sterilization process. ISO 11137 was approved in 1994 and published in 1995. When reviewing the standard you will note that less than 20% of the standard is devoted to requirements and the remainder is guidance on how to comply with the requirements. Future standards developments in radiation sterilization are being focused on providing additional guidance. The guidance that is currently provided in informative annexes of ISO 11137 includes: device/packaging materials, dose setting methods, and dosimeters and dose measurement, currently, there are four Technical Reports being developed to provide additional guidance: 1. AAMI Draft TIR, 'Radiation Sterilization Material Qualification' 2. ISO TR 13409-1996, 'Sterilization of health care products - Radiation sterilization - Substantiation of 25 kGy as a sterilization dose for small or infrequent production batches' 3. ISO Draft TR, 'Sterilization of health care products - Radiation sterilization Selection of a sterilization dose for a single production batch' 4. ISO Draft TR, 'Sterilization of health care products - Radiation sterilization-Product Families, Plans for Sampling and Frequency of Dose Audits'

  1. Birth planning and sterilization in China.

    Science.gov (United States)

    Short, S E; Linmao, M; Wentao, Y

    2000-11-01

    Sterilization is the most prevalent method of contraception in China. Approximately half of all women of reproductive age report that they or their husbands are sterilized. Using data from the China Health and Nutrition Survey we describe patterns of sterilization in eight Chinese provinces. With a discrete-time event history model we investigate the link between characteristics of local birth planning policy and the risk of sterilization. After controlling for parity, the risk of sterilization is highest in communities where birth planning policy is least strong as measured by exceptions to the one-child policy. These results suggest that couples with more flexibility in family building may have less control over contraceptive method use. Other factors affecting the risk of sterilization are a woman's age, parity, and whether or not she has a son. Our results emphasize the importance of taking into account multiple dimensions of reproductive behaviour when assessing one-child policy changes.

  2. Mechanisms of the Innate Defense Regulator Peptide-1002 Anti-Inflammatory Activity in a Sterile Inflammation Mouse Model.

    Science.gov (United States)

    Wu, Bing Catherine; Lee, Amy Huei-Yi; Hancock, Robert E W

    2017-11-15

    Innate defense regulator (IDR) peptide-1002 is a synthetic host defense peptide derivative with strong anti-inflammatory properties. Extending previous data, IDR-1002 suppressed in vitro inflammatory responses in RAW 264.7 murine monocyte/macrophage cells challenged with the TLR4 agonist LPS and TLR2 agonists lipoteichoic acid and zymosan. To investigate the anti-inflammatory mechanisms of IDR-1002 in vivo, the PMA-induced mouse ear inflammation model was used. Topical IDR-1002 treatment successfully dampened PMA-induced ear edema, proinflammatory cytokine production, reactive oxygen and nitrogen species release, and neutrophil recruitment in the ears of CD1 mice. Advanced RNA transcriptomic analysis on the mouse ear transcriptome revealed that IDR-1002 reduced sterile inflammation by suppressing the expression of transmembrane G protein-coupled receptors (class A/1 rhodopsin-like), including receptors for chemokines, PGs, histamine, platelet activating factor, and anaphylatoxin. IDR-1002 also dampened the IFN-γ response and repressed the IFN regulatory factor 8-regulated network that controls central inflammatory pathways. This study demonstrates that IDR-1002 exhibits strong in vitro and in vivo anti-inflammatory activities, informs the underlying anti-inflammatory mechanisms, and reveals its potential as a novel therapeutic for inflammatory diseases. Copyright © 2017 by The American Association of Immunologists, Inc.

  3. Reliability of laparoscopic compared with hysteroscopic sterilization at 1 year: a decision analysis.

    Science.gov (United States)

    Gariepy, Aileen M; Creinin, Mitchell D; Schwarz, Eleanor B; Smith, Kenneth J

    2011-08-01

    To estimate the probability of successful sterilization after an hysteroscopic or laparoscopic sterilization procedure. An evidence-based clinical decision analysis using a Markov model was performed to estimate the probability of a successful sterilization procedure using laparoscopic sterilization, hysteroscopic sterilization in the operating room, and hysteroscopic sterilization in the office. Procedure and follow-up testing probabilities for the model were estimated from published sources. In the base case analysis, the proportion of women having a successful sterilization procedure on the first attempt is 99% for laparoscopic sterilization, 88% for hysteroscopic sterilization in the operating room, and 87% for hysteroscopic sterilization in the office. The probability of having a successful sterilization procedure within 1 year is 99% with laparoscopic sterilization, 95% for hysteroscopic sterilization in the operating room, and 94% for hysteroscopic sterilization in the office. These estimates for hysteroscopic success include approximately 6% of women who attempt hysteroscopically but are ultimately sterilized laparoscopically. Approximately 5% of women who have a failed hysteroscopic attempt decline further sterilization attempts. Women choosing laparoscopic sterilization are more likely than those choosing hysteroscopic sterilization to have a successful sterilization procedure within 1 year. However, the risk of failed sterilization and subsequent pregnancy must be considered when choosing a method of sterilization.

  4. Cytotoxicity of poly(96L/4D-lactide) : the influence of degradation and sterilization

    NARCIS (Netherlands)

    Cordewener, FW; Joziasse, CAP; Schmitz, JP; Bos, RRM; Rozema, FR; Pennings, AJ

    2000-01-01

    The cytotoxicity of poly(96L/4D-lactide) (PLA96), and of its accumulated degradation products, was investigated following different sterilization methods and pre-determined heat-accelerated degradation intervals. PLA96 samples sterilized by either steam, ethylene oxide, or gamma irradiation were

  5. Genomic networks of hybrid sterility.

    Directory of Open Access Journals (Sweden)

    Leslie M Turner

    2014-02-01

    Full Text Available Hybrid dysfunction, a common feature of reproductive barriers between species, is often caused by negative epistasis between loci ("Dobzhansky-Muller incompatibilities". The nature and complexity of hybrid incompatibilities remain poorly understood because identifying interacting loci that affect complex phenotypes is difficult. With subspecies in the early stages of speciation, an array of genetic tools, and detailed knowledge of reproductive biology, house mice (Mus musculus provide a model system for dissecting hybrid incompatibilities. Male hybrids between M. musculus subspecies often show reduced fertility. Previous studies identified loci and several X chromosome-autosome interactions that contribute to sterility. To characterize the genetic basis of hybrid sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL. Many trans eQTL cluster into eleven 'hotspots,' seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL-but not cis eQTL-were substantially lower when mapping was restricted to a 'fertile' subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. The integrated mapping approach we employed is

  6. Model-based ECT signal interpretation and experimental verification for the quantitative flaw characterization in steam generator tubes

    International Nuclear Information System (INIS)

    Song, Sung Jin; Kim, Young Hwan; Kim, Eui Lae; Chung, Tae Eon; Yim, Chang Jae

    2002-01-01

    The model-based inversion tools for eddy current signals have been developed by the novel combination of neural networks and finite element modeling for quantitative flaw characterization in steam generator tubes. In the present work, interpretation of experimental eddy current signals was carried out in order to validate the developed inversion tools. A database was constructed using the synthetic flaw signals generated by the finite element modeling. The hybrid neural networks of a PNN classifier and BPNN size estimators were trained using the synthetic signals. Experimental eddy current signals were obtained from axisymmetric artificial flaws. Interpretations of flaws were carried out by feeding experimental signals into the neural networks. The results of interpretations were excellent, so that the developed inversion tools would be applicable to the interpretation of experimental eddy current signals.

  7. Biosorptive uptake of arsenic(V) by steam activated carbon from mung bean husk: equilibrium, kinetics, thermodynamics and modeling

    Science.gov (United States)

    Mondal, Sandip; Aikat, Kaustav; Halder, Gopinath

    2017-12-01

    The present investigation emphasizes on the biosorptive removal of toxic pentavalent arsenic from water using steam activated carbon prepared from mung bean husk (SAC-MBH). Characterization of the synthesized sorbent was done using different instrumental techniques, i.e., SEM, BET and point of zero charge. Sorptive uptake of As(V) over steam activated MBH as a function of pH (3-9), agitation speed (40-200 rpm), dosage (50-1000 mg) and temperature (298-313 K) was studied by batch process at arsenic concentration of 2 mg L-1. Lower pH increases the arsenic removal over the pH range of 3-9. Among three adsorption isotherm models examined, Langmuir model was observed to show superior results over Freundlich model. The mean sorption energy (E) estimated by Dubinin-Radushkevich model suggested that the process of adsorption was chemisorption. Thermodynamic parameters confer that the sorption process was spontaneous, exothermic and feasible in nature. The pseudo-second-order rate kinetics of arsenic gave better correlation coefficients as compared to pseudo-first-order kinetics equation. Three process parameters, viz. adsorbent dosage, agitation speed and pH were opted for optimizing As(V) elimination using central composite design matrix of response surface methodology (RSM). The identical design setup was used for artificial neural network (ANN) for comparing its prediction capability with RSM towards As(V) removal. Maximum arsenic removal was observed to be 98.75% at sorbent dosage 0.75 gm L-1, pH 3.0, agitation speed 160 rpm and temperature 308 K. The study concluded that SAC-MBH could be a competent adsorbent for As(V) removal and ANN model was better in arsenic removal predictability results than RSM model.

  8. Steam generator thermal-hydraulics

    International Nuclear Information System (INIS)

    Inch, W.W.; Scott, D.A.; Carver, M.B.

    1980-01-01

    This paper discusses a code for detailed numerical modelling of steam generator thermal-hydraulics, and describes related experimental programs designed to promote in-depth understanding of three-dimensional two-phase flow. (auth)

  9. Coupled Model of Heat and Mass Balance for Droplet Growth in Wet Steam Non-Equilibrium Homogeneous Condensation Flow

    Directory of Open Access Journals (Sweden)

    Xu Han

    2017-12-01

    Full Text Available Because of the complexity of wet steam two-phase condensation flow, many problems remain to be solved. The important part of condensation theory—the calculation of the water droplet growth model in the transition zone—is not ideal; thus, it is necessary to develop a water droplet growth model with full-scale range. On the basis of the heat and mass transfer equilibrium in droplet growth, a coupled model of heat and mass balance for droplet growth is proposed. To verify the accuracy of this model, the differences and applicable ranges of various models were analysed using the experimental data of Peters and Meyer and two widely used models. In the free molecular flow region, the heat and mass balance model coincides with the Young low-pressure correction model. In the transition region, the heat and mass balance model agrees well with the experimental values of Peters and Meyer. In the continuous flow region, the heat and mass balance model coincides with the Gyarmathy model. Therefore, the heat and mass balance model can be used to accurately describe the growth process of water droplets in the arbitrary range of Knudsen numbers.

  10. Doppler method leak detection for LMFBR steam generators. Pt. 1. Experimental results of bubble detection using small models

    International Nuclear Information System (INIS)

    Kumagai, Hiromichi

    1999-01-01

    To prevent the expansion of the tube damage and to maintain structural integrity in the steam generators (SGs) of fast breeder reactors (FBRs), it is necessary to detect precisely and immediately the leakage of water from heat transfer tubes. Therefore, an active acoustic method was developed. Previous studies have revealed that in practical steam generators the active acoustic method can detect bubbles of 10 l/s within 10 seconds. To prevent the expansion of damage to neighboring tubes, it is necessary to detect smaller leakages of water from the heat transfer tubes. The Doppler method is designed to detect small leakages and to find the source of the leak before damage spreads to neighboring tubes. To evaluate the relationship between the detection sensitivity of the Doppler method and the bubble volume and bubble size, the structural shapes and bubble flow conditions were investigated experimentally, using a small structural model. The results show that the Doppler method can detect the bubbles under bubble flow conditions, and it is sensitive enough to detect small leakages within a short time. The doppler method thus has strong potential for the detection of water leakage in SGs. (author)

  11. Current experience and a new modeling on water hammer due to steam condensation in PWR secondary system

    International Nuclear Information System (INIS)

    Kawanishi, K.; Kasahara, J.; Ueno, T.; Suzuta, T.

    1998-01-01

    There have been possibilities to occur water hammer in pipelines of turbine system for nuclear or fossil fuel power plants. According to the NUREG report, approximately 150 events have been reported since 1969, we also have an experience recently. Water hammer occurs due to sudden steam condensation with pressure pulse. This kind of pressure pulses has been made by alternative producing and condensing of steam slug in the pipe and its frequency relates subcooling and pipe structures. This paper presents our current experience on water hammer with some experimental studies. The present experiment has been performed to obtain the data base for evaluating the pressure pulses. The test pipe was horizontal tubes with dead end connected to vertical tube which simulating drain line in PWR secondary system. The main results are shown as follows; Magnitude of pressure pulse depends drain velocity and initial subcooling. Pipe structure effects on the frequency and continual time of water hammer phenomenon. A new modeling for quantitative explanation of the phenomena is also presented

  12. The effect of the number of condensed phases modeled on aerosol behavior during an induced steam generator tube rupture sequence

    International Nuclear Information System (INIS)

    Bixler, N.E.; Schaperow, J.H.

    1998-06-01

    VICTORIA is a mechanistic computer code designed to analyze fission product behavior within a nuclear reactor coolant system (RCS) during a severe accident. It provides detailed predictions of the release of radioactive and nonradioactive materials from the reactor core and transport and deposition of these materials within the RCS. A recently completed independent peer review of VICTORIA, while confirming the overall adequacy of the code, recommended a number of modeling improvements. One of these recommendations, to model three rather than a single condensed phase, is the focus of the work reported here. The recommendation has been implemented as an option so that either a single or three condensed phases can be treated. Both options have been employed in the study of fission product behavior during an induced steam generator tube rupture sequence. Differences in deposition patterns and mechanisms predicted using these two options are discussed

  13. Gamma-Irradiated Sterile Cornea for Use in Corneal Transplants in a Rabbit Model.

    Science.gov (United States)

    Yoshida, Junko; Heflin, Thomas; Zambrano, Andrea; Pan, Qing; Meng, Huan; Wang, Jiangxia; Stark, Walter J; Daoud, Yassine J

    2015-01-01

    Gamma irradiated corneas in which the donor keratocytes and endothelial cells are eliminated are effective as corneal lamellar and glaucoma patch grafts. In addition, gamma irradiation causes collagen cross inking, which stiffens collagen fibrils. This study evaluated gamma irradiated corneas for use in corneal transplantations in a rabbit model comparing graft clarity, corneal neovascularization, and edema. Penetrating keratoplasty was performed on rabbits using four types of corneal grafts: Fresh cornea with endothelium, gamma irradiated cornea, cryopreserved cornea, and fresh cornea without endothelium. Slit lamp examination was performed at postoperative week (POW) one, two, and four. Corneal clarity, edema, and vascularization were graded. Confocal microscopy and histopathological evaluation were performed. A P cornea with endothelium compared to the other three groups (P cornea scored better than the cryopreserved and fresh cornea without endothelium groups in clarity (0.9 vs. 1.5 and 2.6, respectively), and edema (0.6 vs. 0.8 and 2.0, respectively). The gamma irradiated corneas, cryopreserved corneas and the fresh corneas without endothelium, developed haze and edema after POW 2. Gamma irradiated cornea remained statistically significantly clearer than cryopreserved and fresh cornea without endothelium during the observation period (P cornea. Gamma irradiated corneas remained clearer and thinner than the cryopreserved cornea and fresh cornea without endothelium. However, this outcome is transient. Gamma irradiated corneas are useful for lamellar and patch grafts, but cannot be used for penetrating keratoplasty.

  14. Advanced technologies on steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Sakata, Kaoru; Nakamura, Yuuki [Mitsubishi Heavy Industry Co., Takasago (Japan); Nakamori, Nobuo; Mizutani, Toshiyuki; Uwagawa, Seiichi; Saito, Itaru [Mitsubishi Heavy Industry Co., Kobe (Japan); Matsuoka, Tsuyoshi [Mitsubishi Heavy Industry Co., Yokohama (Japan)

    1997-12-31

    The thermal-hydraulic tests for a horizontal steam generator of a next-generation PWR (New PWR-21) were performed. The purpose of these tests is to understand the thermal-hydraulic behavior in the secondary side of horizontal steam generator during the plant normal operation. A test was carried out with cross section slice model simulated the straight tube region. In this paper, the results of the test is reported, and the effect of the horizontal steam generator internals on the thermalhydraulic behavior of the secondary side and the circulation characteristics of the secondary side are discussed. (orig.). 3 refs.

  15. An homogeneous model of steam generator to simulate operational transiento and accidents in PWR nuclear power plants

    International Nuclear Information System (INIS)

    Souza, A.L. de.

    1981-07-01

    GEVAP - A digital computer code was developed to simulate the thermodynamic transient behaviour of steam generators. The steam generator is divided in heating sections. In each section, the conservation equations of mass and energy are integrated numerically, using a predictor-corrector method. As good reslts where obtained, as compared to transients simulated using more detainled codes, it is concluded that GEVAP can be included as the steam generator module of a more complete systems simulation code for PWR's. (E.G.) [pt

  16. Sterile neutrino constraints from cosmology

    DEFF Research Database (Denmark)

    Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.

    2012-01-01

    The presence of light particles beyond the standard model's three neutrino species can profoundly impact the physics of decoupling and primordial nucleosynthesis. I review the observational signatures of extra light species, present constraints from recent data, and discuss the implications of po...... of possible sterile neutrinos with O(eV)-masses for cosmology....

  17. 2D heat and mass transfer modeling of methane steam reforming for hydrogen production in a compact reformer

    International Nuclear Information System (INIS)

    Ni Meng

    2013-01-01

    Highlights: ► A heat and mass transfer model is developed for a compact reformer. ► Hydrogen production from methane steam reforming is simulated. ► Increasing temperature greatly increases the reaction rates at the inlet. ► Temperature in the downstream is increased at higher rate of heat supply. ► Larger permeability enhances gas flow and reaction rates in the catalyst layer. - Abstract: Compact reformers (CRs) are promising devices for efficient fuel processing. In CRs, a thin solid plate is sandwiched between two catalyst layers to enable efficient heat transfer from combustion duct to the reforming duct for fuel processing. In this study, a 2D heat and mass transfer model is developed to investigate the fundamental transport phenomenon and chemical reaction kinetics in a CR for hydrogen production by methane steam reforming (MSR). Both MSR reaction and water gas shift reaction (WGSR) are considered in the numerical model. Parametric simulations are performed to examine the effects of various structural/operating parameters, such as pore size, permeability, gas velocity, temperature, and rate of heat supply on the reformer performance. It is found that the reaction rates of MSR and WGSR are the highest at the inlet but decrease significantly along the reformer. Increasing the operating temperature raises the reaction rates at the inlet but shows very small influence in the downstream. For comparison, increasing the rate of heat supply raises the reaction rates in the downstream due to increased temperature. A high gas velocity and permeability facilitates gas transport in the porous structure thus enhances reaction rates in the downstream of the reformer.

  18. Energy efficiency analysis of steam ejector and electric vacuum pump for a turbine condenser air extraction system based on supervised machine learning modelling

    International Nuclear Information System (INIS)

    Strušnik, Dušan; Marčič, Milan; Golob, Marjan; Hribernik, Aleš; Živić, Marija; Avsec, Jurij

    2016-01-01

    Highlights: • Steam ejector pump and electric liquid ring vacuum pump are analysed and modelled. • A supervised machine learning models by using real process data are applied. • The equation of ejector pumped mass flow from steam turbine condenser was solved. • The loss of specific energy capable of work in a SEPS or LRVP component was analysed. • The economic efficiency analysis per different coal heating values was made. - Abstract: This paper compares the vapour ejector and electric vacuum pump power consumptions with machine learning algorithms by using real process data and presents some novelty guideline for the selection of an appropriate condenser vacuum pump system of a steam turbine power plant. The machine learning algorithms are made by using the supervised machine learning methods such as artificial neural network model and local linear neuro-fuzzy models. The proposed non-linear models are designed by using a wide range of real process operation data sets from the CHP system in the thermal power plant. The novelty guideline for the selection of an appropriate condenser vacuum pumps system is expressed in the comparative analysis of the energy consumption and use of specific energy capable of work. Furthermore, the novelty is expressed in the economic efficiency analysis of the investment taking into consideration the operating costs of the vacuum pump systems and may serve as basic guidelines for the selection of an appropriate condenser vacuum pump system of a steam turbine.

  19. Mathematical modelling of stress-deformation state of the steam generator collector (WWER-type) under pressure loading during fracture mechanics calculations

    International Nuclear Information System (INIS)

    Zaitsev, M.; Lyssakov, V.

    1993-01-01

    This paper describes a steam generator collector (WWER-type) designed as part of a Russian reactor power station. The collector is a thick cylindrical shell with a constant inner diameter of 850 mm and a height of 4,970 mm. The wall thickness varies from 78 to 163 mm. In the thicker section, a series of holes allows connection of steam generator heat exchanging tubes. Because of design considerations, the tubes are not symmetrically located about the circumference of the collector. This paper presents a model of the stress concentrations resulting from this design feature for a device operating at a nominal pressure of 16 MPa. 4 refs., 8 figs

  20. CAREM-25 Steam Generator Stability Analysis

    International Nuclear Information System (INIS)

    Rabiti, A.; Delmastro, D.

    2003-01-01

    In this work the stability of a once-through CAREM-25 steam generator is analyzed.A fix nodes numerical model, that allows the modelling of the liquid, two-phase and superheated steam zones, is implemented.This model was checked against a mobile finite elements model under saturated steam conditions at the channel exit and a good agreement was obtained.Finally the stability of a CAREM steam generator is studied and the range of in let restrictions that a assure the system stability is analyzed

  1. A synthesis of ten years' tests on scale models of LMFBR steam generators at the CGVS facility

    International Nuclear Information System (INIS)

    Fontaine, J.P.; Quinet, J.L.

    1982-01-01

    Electricite de France has built a high power sodium heated steam generator (SG) facility (CGVS), capable of reproducing all possible operating conditions, to study the behaviour of scale-models of industrial apparatuses. The main findings of the experiments were as follows: - heat exchange surfaces remained perfectly leak proof; - hydrogen detection in the sodium and argon constitute additional systems for monitoring the impermeability to leaks of a SG with a free sodium surface; - extrapolation of the findings to the SUPER PHENIX SG shows that water leaking at a rate of 100 mg/s would induce in ten minutes a 50% rise of the signal produced by the hydrogen monitoring device in the sodium; - acoustic method can detect leaks of the order of one g/s in a 45 MW SG sited in an industrial environment

  2. [Regret of female sterilization].

    Science.gov (United States)

    Öhman, Malin Charlotta; Andersen, Lars Franch

    2015-11-16

    Regret of sterilization is inversely correlated to age at the time of sterilization. The minimum age for legal sterilization in Denmark has recently been lowered to 18 years. In Denmark surgical refertilization has almost completely been replaced by in vitro fertilization (IVF). In recent literature pregnancy results after surgical refertilization are easily comparable to IVF. Refertilization may in some cases be advantageous to IVF treatment. Women requesting reversal of sterilization should be offered individualized evaluation and differentiated treatment. It is recommended that surgical refertilization is performed at very few centres.

  3. TOPFLOW-experiments, development and validation of CFD models for steam-water flows with phase transfer. Final report

    International Nuclear Information System (INIS)

    Lucas, D.; Beyer, M.; Krepper, E.

    2011-11-01

    The aim of the project was the qualification of CFD codes for steam-water flows with phase transfer. While CFD methods for single-phase flows are already widely used for industrial applications, a corresponding use for two-phase flows is only at the beginning due to the complex structure of the interface and the related interactions between the phases. For the further development and validation of appropriate closure models, experimental data with high spatial and temporal resolution are required. Such data were obtained at the TOPFLOW test facility of HZDR by combination of experiments at realistic parameters for the nuclear reactor safety (large scales, high pressures and temperatures) with innovative measuring techniques. The wire-mesh sensor technology, which provides detailed information on the structure of the interface, was applied in adiabatic air-water experiments as well as in condensation and pressure relief experiments in a large DN200 pipe. As the result of the project, extensive databases with high quality are available. The technology for the fast X-ray tomography, which allows measurements without influencing the flow, was further developed and successfully applied in a first test series. High-resolution data were also obtained from experiments in a model of the hot leg of a pressurized water reactor for different flow situations, including counter-current flow limitation. For the corresponding steam-water experiments conducted at pressures of up to 5 MPa, the newly developed pressure tank technology was successfully used for the first time. For the qualification of CFD codes for two-phase flows the Inhomogeneous MUSIG model was extended in co.operation with ANSYS to consider phase transfer and validated on the basis of the above mentioned TOPFLOW experiments. In addition, improvements were achieved e.g. for turbulence modelling in bubbly flows and simulations were done to validate models for bubble forces and bubble coalescence and breakup. A

  4. Sterile Neutrino Search with MINOS

    Energy Technology Data Exchange (ETDEWEB)

    Devan, Alena V. [College of William and Mary, Williamsburg, VA (United States)

    2015-08-01

    MINOS, Main Injector Neutrino Oscillation Search, is a long-baseline neutrino oscillation experiment in the NuMI muon neutrino beam at the Fermi National Accelerator Laboratory in Batavia, IL. It consists of two detectors, a near detector positioned 1 km from the source of the beam and a far detector 734 km away in Minnesota. MINOS is primarily designed to observe muon neutrino disappearance resulting from three flavor oscillations. The Standard Model of Particle Physics predicts that neutrinos oscillate between three active flavors as they propagate through space. This means that a muon-type neutrino has a certain probability to later interact as a different type of neutrino. In the standard picture, the neutrino oscillation probabilities depend only on three neutrino flavors and two mass splittings, Δm2. An anomaly was observed by the LSND and MiniBooNE experiments that suggests the existence of a fourth, sterile neutrino flavor that does not interact through any of the known Standard Model interactions. Oscillations into a theoretical sterile flavor may be observed by a deficit in neutral current interactions in the MINOS detectors. A distortion in the charged current energy spectrum might also be visible if oscillations into the sterile flavor are driven by a large mass-squared difference, ms2 ~ 1 eV2. The results of the 2013 sterile neutrino search are presented here.

  5. Simulation of biomass-steam gasification in fluidized bed reactors: Model setup, comparisons and preliminary predictions.

    Science.gov (United States)

    Yan, Linbo; Lim, C Jim; Yue, Guangxi; He, Boshu; Grace, John R

    2016-12-01

    A user-defined solver integrating the solid-gas surface reactions and the multi-phase particle-in-cell (MP-PIC) approach is built based on the OpenFOAM software. The solver is tested against experiments. Then, biomass-steam gasification in a dual fluidized bed (DFB) gasifier is preliminarily predicted. It is found that the predictions agree well with the experimental results. The bed material circulation loop in the DFB can form automatically and the bed height is about 1m. The voidage gradually increases along the height of the bed zone in the bubbling fluidized bed (BFB) of the DFB. The U-bend and cyclone can separate the syngas in the BFB and the flue gas in the circulating fluidized bed. The concentration of the gasification products is relatively higher in the conical transition section, and the dry and nitrogen-free syngas at the BFB outlet is predicted to be composed of 55% H 2 , 20% CO, 20% CO 2 and 5% CH 4 . Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Modelling the Turbocharger Cut Off Application Due to Slow Steaming Operation 12RTA96C-B Engine

    Directory of Open Access Journals (Sweden)

    Karsten Wehner

    2017-09-01

    Full Text Available Out of the total operational costs of a ship, fuel costs account for by far the highest proportion. In view of the global economic situation and the rising oil prices, shipowners and charterers are looking for solutions to cut costs by reducing fuel consumption. Low load operation, also well-known as “slow steaming”, represents the currently most effective and popular measure to cut fuel costs and, in consequence, the total operational costs for increased competitiveness in the market. Low load operation is possible and there is an increasing trend to operate in these very low engine load ranges. As the engines were not designed for this operational condition, various retrofit modifications to the engine can compensate for this. By using low load operation, the reduction of the RPM gives problems when sailing at low speed.  A turbocharger (TC compresses inlet air to a high pressure and after cooling this compressed air it results in higher mass of air in the cylinder. But when running at a low power load this air reaches temperatures that are too low for an optimal combustion process. One of the solution comes from the company Wärtsilä. They install so called “low steam engine kits”. When this kit is installed it allows the engine operators to cut off one turbocharger of the engine, this result’s in a higher RPM for the operating turbochargers. When the remaining TC’s have a higher RPM their efficiency improves and gives the engine more air for combustion.The goal of this Bachelor thesis is to make a calculation modelling and prove that by switching off one or more turbocharger on the system will improve the efficiency in slow steaming operation. Beside that, this thesis is aims to estimated the performance of the engine in both operation condition.

  7. Proposed Philippine radiation-sterilization plant, and a survey of market potential

    International Nuclear Information System (INIS)

    Singson, C.C.; Ibe, L.D.

    1975-01-01

    The paper deals with a study to assess the market potential of radiation sterilization in the Philippines. A market survey conducted with the technical assistance of an IAEA expert from India shows that most of the pharmaceutical industries engaged in the manufacture of medical products unanimously agree that there is an urgent need for a centralized radiation sterilization plant to meet the demands of sterilization of most of their products and packaging materials. The authorities of the government and some of the private hospitals surveyed are also very keen for the establishment of a sterilization facility since most modern medical products and devices are made of heat-sensitive thermoplastics which cannot be heat or steam sterilized. Availability of sterile products will help improve the public health standards of the population. The scope of the utilization of a radiation-sterilization facility in Diliman Quezon City is also discussed. (author)

  8. A theoretical critical heat flux model for low-pressure, low-mass-flux, and low-steam quality conditions

    International Nuclear Information System (INIS)

    Weihsiao Ho; Kuanchywan Tu; Baushei Pei; Chinjang Chang

    1993-01-01

    The critical heat flux (CHF) is the maximum heat flux just before a boiling crisis; its importance as a measurement of nuclear reactor power capability design as well as in the safety of reactors has been recognized. With emphasis on CHF behavior under subcooled and low-quality (i.e., 2 ·s), an improved model that uses the sublayer dry out theory has been developed. Based on experimental observations of CHF, the model assumes that CHF under such conditions is of the departure from nucleate boiling type. Based on the postulation that CHF is triggered by Helmholtz instability in the sublayer steam-liquid system, the model was developed by a simple energy balance of liquid sublayer evaporation as the vapor blanket tends to disturb the balance between the buoyancy force and the drag force exerted upon it. The model is compared with the well-known Biasi et al. correlation as well as the Atomic Energy of Canada Limited lookup table against 102 uniformly heated round tube CHF data and 34 nonuniformly heated round tube CHF data. The comparison shows that the model provides better accuracy and a reasonable agreement between the predicted values and experimental CHF data

  9. Modeling of asphaltene precipitation due to steam and n-alkane co-injection in the ES-SAGD process

    Energy Technology Data Exchange (ETDEWEB)

    Badamchizadeh, A.; Kohse, Bruce F.; Kumar, A. [Computer Modelling Group Ltd (Canada)

    2011-07-01

    This paper provides an insight into the SAGD process in general, and the formation of asphaltene participates in the hybrid ES-SAGD process in particular. The objective of this work was to build an EoS model able to calculate the physical and chemical properties of the bitumen and n-alkane mixture, develop a model to quantify asphaltene participates in bitumen due to n-alkane injection, and investigate their effect on the ES-SAGD process. Athabasca bitumen properties identified under various test conditions and from the results of previous efforts, mainly the SimDist experimental data, were illustrated. These data were used to develop the EoS model, which in turn was used to generate the STARS thermal simulator. Overall, the EoS model was successfully developed and hence was able to predict bitumen and n-heptane properties. Moreover, asphaltene deposition in the ES-SAGD process was modeled in the thermal simulator its effect in causing oil blockage and restrictions in the steam chamber over a long run of the process was demonstrated.

  10. Modular ionizing sterilizer (MIS)

    International Nuclear Information System (INIS)

    Freijo, Jose L.

    1999-01-01

    A transportable device designed to sterilize medical material and wastes by gamma irradiation is described. The sterilizer is formed by three modules: one of the modules contains the gamma source and can be removed to transport and transfer the source, the other modules are designed to introduce and draw out the materials to be irradiated

  11. Safety and efficacy of hysteroscopic sterilization compared with laparoscopic sterilization: an observational cohort study.

    Science.gov (United States)

    Mao, Jialin; Pfeifer, Samantha; Schlegel, Peter; Sedrakyan, Art

    2015-10-13

    To compare the safety and efficacy of hysteroscopic sterilization with the "Essure" device with laparoscopic sterilization in a large, all-inclusive, state cohort. Population based cohort study. Outpatient interventional setting in New York State. Women undergoing interval sterilization procedure, including hysteroscopic sterilization with Essure device and laparoscopic surgery, between 2005 and 2013. Safety events within 30 days of procedures; unintended pregnancies and reoperations within one year of procedures. Mixed model accounting for hospital clustering was used to compare 30 day and 1 year outcomes, adjusting for patient characteristics and other confounders. Time to reoperation was evaluated using frailty model for time to event analysis. We identified 8048 patients undergoing hysteroscopic sterilization and 44,278 undergoing laparoscopic sterilization between 2005 and 2013 in New York State. There was a significant increase in the use of hysteroscopic procedures during this period, while use of laparoscopic sterilization decreased. Patients undergoing hysteroscopic sterilization were older than those undergoing laparoscopic sterilization and were more likely to have a history of pelvic inflammatory disease (10.3% v 7.2%, Psterilization was not associated with a higher risk of unintended pregnancy (odds ratio 0.84 (95% CI 0.63 to 1.12)) but was associated with a substantially increased risk of reoperation (odds ratio 10.16 (7.47 to 13.81)) compared with laparoscopic sterilization. Patients undergoing hysteroscopic sterilization have a similar risk of unintended pregnancy but a more than 10-fold higher risk of undergoing reoperation compared with patients undergoing laparoscopic sterilization. Benefits and risks of both procedures should be discussed with patients for informed decisions making. © Mao et al 2015.

  12. Experimental study of the zirconium alloy oxidation under high pressure of steam and modelling of the mechanisms

    International Nuclear Information System (INIS)

    Dali, Yacoub

    2007-01-01

    The corrosion of the cladding materials used for the fuel rods is one of the limiting factor of their lifetime in light water reactors. In this field, the aim of the nuclear industry is today to increase the time and the number of cycles and to submit the claddings in zirconium alloys to higher corrosive conditions. In this way, new alloys devoted to replace the standard Zircaloy-4, for instance Nb containing alloys, have been recently developed and licensed and show better corrosion resistance. A better understanding of the corrosion mechanisms of the zirconium alloys is necessary to predict the corrosion behaviour of these materials. In this work, the oxidation rate of model alloys of two metallurgic families has been studied in steam in a pressure range between 100 milli-bars and 100 bars. The Zircaloy type alloys contain as alloying elements oxygen and/or tin and/or iron and chromium. For the Zr-Nb family, three niobium contents have been studied, respectively 0.2, 0.4 and 1 weight percent of niobium. Our objectives were to understand the variations of the reactivity between the low pressure and the high pressure range, in quantifying the dependency of the corrosion rate with the steam pressure and the alloying element concentrations. The segregation process of the niobium at the surface has also been studied on the Zr-Nb alloys. During this work, a magnetic suspension thermo-balance has been developed and used to follow in-situ the corrosion rate at high pressure of water vapour. The oxide layers have been characterized by many techniques, macro and micro-photo-electrochemistry, XRD, FEG-SEM, XPS, HR-TEM and SIMS. For the Zircaloy type alloys, we have confirmed the major role of the intermetallic precipitates Zr(Fe,Cr) 2 on the corrosion resistance. Unlike the standard Zircaloy-4, for which the oxidation rate does not depend on the pressure of the water vapour and is thus limited by the vacancy diffusion in the oxide layer, we have shown that the rate of the

  13. Steam Digest 2002

    Energy Technology Data Exchange (ETDEWEB)

    2003-11-01

    Steam Digest 2002 is a collection of articles published in the last year on steam system efficiency. DOE directly or indirectly facilitated the publication of the articles through it's BestPractices Steam effort. Steam Digest 2002 provides a variety of operational, design, marketing, and program and program assessment observations. Plant managers, engineers, and other plant operations personnel can refer to the information to improve industrial steam system management, efficiency, and performance.

  14. Seeking sterile neutrinos in Finslerian cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Deng [Nankai University, Theoretical Physics Division, Chern Institute of Mathematics, Tianjin (China); Meng, Xin-He [Nankai University, Department of Physics, Tianjin (China)

    2017-11-15

    For the first time, to search for sterile neutrinos in the framework of Finler geometry, we constrain four cosmological models using the most stringent constraint we can provide so far. We find that the Finslerian massless sterile neutrino model can, respectively, give a better cosmological fit to data and alleviate the current H{sub 0} tension more effectively than the other three models. For the Finslerian massless sterile neutrino model, we obtain the constraint N{sub eff} = 3.237{sup +0.092}{sub -0.185}, which is consistent with ΔN{sub eff} > 0 at the 1.03σ confidence level (CL). This gives a very weak hint of massless sterile neutrinos and may imply the non-existence of massless sterile neutrinos in the Finslerian cosmological setting. For the Finslerian massive sterile neutrino model, we obtain the constraints N{sub eff} = 3.143{sup +0.064}{sub -0.066}, which favors ΔN{sub eff} > 0 at the 1.47σ CL, and m{sub ν,sterile}{sup eff} < 0.121 eV at the 2σ CL which is much tighter than the Planck results. This very tight restriction appears to indicate the massive sterile neutrinos are also non-existent in the Finslerian scenarios. Consequently, one may conclude that the sterile neutrinos are possibly non-existent in the Finslerian universe. Our results are compatible with the recent results of the neutrino oscillation experiments implemented by the Daya Bay and MINOS collaborations and the cosmic ray one carried out by the IceCube collaboration. (orig.)

  15. Development of tube rupture evaluation code for FBR steam generator (II). Modification of heat transfer model in sodium side

    International Nuclear Information System (INIS)

    Hamada, H.; Kurihara, A.

    2003-05-01

    The thermal effect of sodium-water reaction jet on neighboring heat transfer tubes was examined to rationally evaluate the structural integrity of the tube for overheating rupture under a water leak in an FBR steam generator. Then, the development of new heat transfer model and the application analysis were carried out. Main results in this paper are as follows. (1) The evaluation method of heat flux and heat transfer coefficient (HTC) on the tube exposed to reaction jet was developed. By using the method, it was confirmed that the heat flux could be realistically evaluated in comparison with the previous method. (2) The HTC between reaction jet and the tube was theoretically examined in the two-phase flow model, and new heat transfer model considering the effect of fluid temperature and cover gas pressure was developed. By applying the model, a tentative experimental correlation was conservatively obtained by using SWAT-1R test data. (3) The new model was incorporated to the Tube Rupture Evaluation Code (TRUE), and the conservatism of the model was confirmed by using sodium-water reaction data such as the SWAT-3 tests. (4) In the application analysis of the PFR large leak event, there was no significant difference of calculation results between the new model and previous one; the importance of depressurization in the tube was confirmed. (5) In the application analysis of the Monju evaporator, it was confirmed that the calculation result in the previous model would be more conservative than that in the new one and that the maximum cumulative damage of 25% could be reduced in the new model. (author)

  16. Status Report on the High-Temperature Steam Electrolysis Plant Model Developed in the Modelica Framework (FY17)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jong Suk [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bragg-Sitton, Shannon M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boardman, Richard D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-08-29

    This report has been prepared as part of an effort to design and build a modeling and simulation (M&S) framework to assess the economic viability of a nuclear-renewable hybrid energy system (N-R HES). In order to facilitate dynamic M&S of such an integrated system, research groups in multiple national laboratories have been developing various subsystems as dynamic physics-based components using the Modelica programming language. In fiscal year 2015 (FY15), Idaho National Laboratory (INL) performed a dynamic analysis of two region-specific N-R HES configurations, including the gas-to-liquid (natural gas to Fischer-Tropsch synthetic fuel) and brackish water reverse osmosis desalination plants as industrial processes. In FY16, INL developed two additional subsystems in the Modelica framework: (1) a high-temperature steam electrolysis (HTSE) plant as a high priority industrial plant to be integrated with a light water reactor (LWR) within an N-R HES and (2) a gas turbine power plant as a secondary energy supply. In FY17, five new components (i.e., a feedwater pump, a multi-stage compression system, a sweep-gas turbine, flow control valves, and pressure control valves) have been incorporated into the HTSE system proposed in FY16, aiming to better realistically characterize all key components of concern. Special attention has been given to the controller settings based on process models (i.e., direct synthesis method), aiming to improve process dynamics and controllability. A dynamic performance analysis of the improved LWR/HTSE integration case was carried out to evaluate the technical feasibility (load-following capability) and safety of such a system operating under highly variable conditions requiring flexible output. The analysis (evaluated in terms of the step response) clearly shows that the FY17 model resulted in superior output responses with much smaller settling times and less oscillatory behavior in response to disturbances in the electric load than those

  17. Optimal design of marine steam turbine

    International Nuclear Information System (INIS)

    Liu Chengyang; Yan Changqi; Wang Jianjun

    2012-01-01

    The marine steam turbine is one of the key equipment in marine power plant, and it tends to using high power steam turbine, which makes the steam turbine to be heavier and larger, it causes difficulties to the design and arrangement of the steam turbine, and the marine maneuverability is seriously influenced. Therefore, it is necessary to apply optimization techniques to the design of the steam turbine in order to achieve the minimum weight or volume by means of finding the optimum combination of design parameters. The math model of the marine steam turbine design calculation was established. The sensitivities of condenser pressure, power ratio of HP turbine with LP turbine, and the ratio of diameter with height at the end stage of LP turbine, which influence the weight of the marine steam turbine, were analyzed. The optimal design of the marine steam turbine, aiming at the weight minimization while satisfying the structure and performance constraints, was carried out with the hybrid particle swarm optimization algorithm. The results show that, steam turbine weight is reduced by 3.13% with the optimization scheme. Finally, the optimization results were analyzed, and the steam turbine optimization design direction was indicated. (authors)

  18. Thermal-hydraulics in recirculating steam generators

    International Nuclear Information System (INIS)

    Carver, M.B.; Carlucci, L.N.; Inch, W.W.R.

    1981-04-01

    This manual describes the THIRST code and its use in computing three-dimensional two-phase flow and heat transfer in a steam generator under steady state operation. The manual is intended primarily to facilitate the application of the code to the analysis of steam generators typical of CANDU nuclear stations. Application to other steam generator designs is also discussed. Details of the assumptions used to formulate the model and to implement the numerical solution are also included

  19. Digital implementation, simulation and tests in MATLAB of the models of Steam line, the turbines, the pressure regulator of a BWR type nucleo electric power plant

    International Nuclear Information System (INIS)

    Lopez R, A.

    2004-01-01

    In this phase of the project they were carried out exhaustive tests to the models of the steam lines, turbines and pressure regulator of a BWR type nucleo electric central for to verify that their tendencies and behaviors are it more real possible. For it, it was necessary to also analyze the transfer functions of the different components along the steam line until the power generator. Such models define alone the dominant poles of the system, what is not limitation to reproduce a wide range of anticipated transitoriness of a power station operation. In the same manner, it was integrated and proved the integrated model form with the models of feeding water of the SUN-RAH, simulating the nuclear reactor starting from predetermined entrances of the prospective values of the vessel. Also it was coupled with the graphic interface developed with the libraries DirectX implementing a specific monitoring panel for this system. (Author)

  20. Phenology, sterility and inheritance of two environment genic male sterile (EGMS) lines for hybrid rice

    NARCIS (Netherlands)

    El-Namaky, R.; Oort, van P.A.J.

    2017-01-01

    Background: There is still limited quantitative understanding of how environmental factors affect sterility of Environment-conditioned genic male sterility (EGMS) lines. A model was developed for this purpose and tested based on experimental data from Ndiaye (Senegal) in 2013-2015. For the two

  1. [Sterilization and eugenics].

    Science.gov (United States)

    Shasha, Shaul M

    2011-04-01

    The term "eugenics" was coined by Francis Galton in 1883 and was defined as the science of the improvement of the human race by better breeding. "Positive eugenics" referred to methods of encouraging the "most fit" to reproduce more often, while "negative eugenics" was related to ways of discouraging or preventing the "less fit" from reproducing by birth control and sterilization. Many western countries adopted eugenics programs including Britain, Canada, Norway, Australia, Switzerland and others. In Sweden more then 62,000 "unfits" were forcibly sterilized. Many states in the U.S.A. had adopted marriage laws with eugenics criteria including forced sterilization. Approximately 64,000 individuals were sterilized. Eugenics considerations also lay behind the adoption of the Immigration Restriction Act of 1924. The Largest plan on eugenics was adopted by the Nazi regime in Germany. Hundreds of thousands of people, who were viewed as being "unfit", were forcibly sterilized by different methods: Surgical sterilization or castration with severe complications and high mortality rates. X-ray irradiation. The method was suggested by Brack, and tested by Schuman using prisoners in Block No. 10 in Auschwitz and Birkenau. Experiments were also performed by Brack on prisoners using the "window method". "Klauberg method"--injection of irritating materials into the uterus. Experiments were conducted using the plant Caladium Seguinum which was believed to have sterilization and castration properties.

  2. Catalytic Steam Reforming of Toluene as a Model Compound of Biomass Gasification Tar Using Ni-CeO2/SBA-15 Catalysts

    Directory of Open Access Journals (Sweden)

    Erik Dahlquist

    2013-07-01

    Full Text Available Nickel supported on SBA-15 doped with CeO2 catalysts (Ni-CeO2/SBA-15 was prepared, and used for steam reforming of toluene which was selected as a model compound of biomass gasification tar. A fixed-bed lab-scale set was designed and employed to evaluate the catalytic performances of the Ni-CeO2/SBA-15 catalysts. Experiments were performed to reveal the effects of several factors on the toluene conversion and product gas composition, including the reaction temperature, steam/carbon (S/C ratio, and CeO2 loading content. Moreover, the catalysts were subjected to analysis of their carbon contents after the steam reforming experiments, as well as to test the catalytic stability over a long experimental period. The results indicated that the Ni-CeO2/SBA-15 catalysts exhibited promising capabilities on the toluene conversion, anti-coke deposition and catalytic stability. The toluene conversion reached as high as 98.9% at steam reforming temperature of 850 °C and S/C ratio of 3 using the Ni-CeO2(3wt%/SBA-15 catalyst. Negligible coke formation was detected on the used catalyst. The gaseous products mainly consisted of H2 and CO, together with a little CO2 and CH4.

  3. Modelling of a steam reformer for fuel cell CHP systems considering intra- and extra-particulate transport phenomena; Modellierung eines Dampfreformers fuer stationaere Brennstoffzellen unter Beruecksichtigung von intra- und extrapartikulaeren Transportphaenomene

    Energy Technology Data Exchange (ETDEWEB)

    Nitzsche, J. [DBI-Gastechnologisches Institut, Freiberg (Germany)

    2009-07-01

    The modelling of methane steam-reforming fixed bed reactors requires detailed knowledge of limiting heat and mass transfer processes at the catalyst particle. Their influence is checked by a single particle model and the results are used to create an exact two-dimensional model of a reformer tube. This model allows for the implementation of an intensive significance analysis, which gives a better understanding of the process and provides for proper dimensioning of steam reformers. (orig.)

  4. Steam atmosphere drying exhaust steam recompression system

    Science.gov (United States)

    Becker, F.E.; Smolensky, L.A.; Doyle, E.F.; DiBella, F.A.

    1994-03-08

    This invention relates to a heated steam atmosphere drying system comprising dryer in combination with an exhaust recompression system which is extremely energy efficient and eliminates dangers known to air dryers. The system uses superheated steam as the drying medium, which recirculates through the system where its heat of evaporation and heat of compression is recovered, thereby providing a constant source of heat to the drying chamber. The dryer has inlets whereby feedstock and superheated steam are fed therein. High heat transfer and drying rates are achieved by intimate contact of the superheated steam with the particles being dried. The dryer comprises a vessel which enables the feedstock and steam to enter and recirculate together. When the feedstock becomes dry it will exit the dryer with the steam and become separated from the steam through the use of a curvilinear louver separator (CLS). The CLS enables removal of fine and ultrafine particles from the dryer. Water vapor separated from the particles in the CLS as superheated steam, may then be recovered and recirculated as steam through the use of a compressor to either directly or indirectly heat the dryer, and a heat exchanger or a heater to directly provide heat to the dryer. This system not only provides a very efficient heat transfer system but results in a minimum carry-over of ultrafine particles thereby eliminating any explosive hazard. 17 figures.

  5. Signatures of extra dimensional sterile neutrinos

    Directory of Open Access Journals (Sweden)

    Werner Rodejohann

    2014-10-01

    Full Text Available We study a large extra dimension model with active and sterile Dirac neutrinos. The sterile neutrino masses stem from compactification of an extra dimension with radius R and are chosen to have masses around eV or keV, in order to explain short-baseline anomalies or act as warm dark matter candidates. We study the effect of the sterile neutrino Kaluza–Klein tower in short-baseline oscillation experiments and in the beta spectrum as measurable by KATRIN-like experiments.

  6. Sterilization by Laparoscopy

    Science.gov (United States)

    ... If pregnancy does occur, the risk of an ectopic pregnancy is higher than in women who did not ... pregnant. Also, the risk of problems, such as ectopic pregnancy, is increased. What are some alternatives to sterilization? ...

  7. Sterilization of space hardware.

    Science.gov (United States)

    Pflug, I. J.

    1971-01-01

    Discussion of various techniques of sterilization of space flight hardware using either destructive heating or the action of chemicals. Factors considered in the dry-heat destruction of microorganisms include the effects of microbial water content, temperature, the physicochemical properties of the microorganism and adjacent support, and nature of the surrounding gas atmosphere. Dry-heat destruction rates of microorganisms on the surface, between mated surface areas, or buried in the solid material of space vehicle hardware are reviewed, along with alternative dry-heat sterilization cycles, thermodynamic considerations, and considerations of final sterilization-process design. Discussed sterilization chemicals include ethylene oxide, formaldehyde, methyl bromide, dimethyl sulfoxide, peracetic acid, and beta-propiolactone.

  8. Contraception Update: Sterilization.

    Science.gov (United States)

    Antell, Karen; Deshmukh, Prium; Brown, Elizabeth J

    2017-11-01

    Female sterilization procedures include postpartum partial salpingectomy via cesarean or minilaparotomy incision, interval laparoscopic procedures, or hysteroscopic placement of microinserts. Rates of failure and serious complications are low and comparable among the various methods. A hysteroscopic procedure requires a 3-month confirmatory hysterosalpingogram before it is considered effective for contraception. Hysteroscopic sterilization has been shown to be associated with a higher reoperation rate than laparoscopic procedures. For male sterilization, vasectomy is a noninvasive and highly effective method. Vasectomy is an outpatient procedure performed under local anesthesia. The procedure requires confirmation of azoospermia with a semen analysis 8 to 16 weeks after the procedure. Patients who are considering sterilization should be counseled about all the available options and the permanent nature of such procedures. Written permission from the American Academy of Family Physicians is required for reproduction of this material in whole or in part in any form or medium.

  9. Auditing radiation sterilization facilities

    Science.gov (United States)

    Beck, Jeffrey A.

    The diversity of radiation sterilization systems available today places renewed emphasis on the need for thorough Quality Assurance audits of these facilities. Evaluating compliance with Good Manufacturing Practices is an obvious requirement, but an effective audit must also evaluate installation and performance qualification programs (validation_, and process control and monitoring procedures in detail. The present paper describes general standards that radiation sterilization operations should meet in each of these key areas, and provides basic guidance for conducting QA audits of these facilities.

  10. [Sterilization: necessity or genocide?].

    Science.gov (United States)

    Muraro, R M

    1991-01-01

    densities in the world but are highly developed. On the other hand Bolivia and Peru are underdeveloped but have very low population densities. Brazil has 1 of the lowest population densities in the world at 14 inhabitants per sq km. Rural- urban migration in the past few decades has transferred a hugh contingent of rural dwellers to the outskirts of the large and medium sized cities. Brazil's perverse economic model that concentrates income, focuses on exports, and encourages latifundia, and not population density, is responsible for urban growth. A truly efficient demographic policy would seek a transformation of the economic model. Another myth is that environmental damage is caused by poverty and rapid population growth. The most polluting countries of the world are the most developed and richest. Population movements in Latin American countries with mass sterilization programs should divert the funds to programs improving the status of women, who could then control their own fertility.

  11. Steam reforming of biomass gasification tar using benzene as a model compound over various Ni supported metal oxide catalysts.

    Science.gov (United States)

    Park, Hyun Ju; Park, Sung Hoon; Sohn, Jung Min; Park, Junhong; Jeon, Jong-Ki; Kim, Seung-Soo; Park, Young-Kwon

    2010-01-01

    The steam reforming of benzene as a model compound of biomass gasification tar was carried out over various Ni/metal oxide catalysts. The effects of the support, temperature, Ni-precursor, Ni loading and reaction time were examined, and their catalytic performance was compared with that of a commercial Ni catalyst. Among the Ni/metal oxide catalysts used, 15 wt% Ni/CeO(2)(75%)-ZrO(2)(25%) showed the highest catalytic performance owing to its greater redox characteristics and increased surface area, irrespective of the reaction temperature. The catalytic activity of 15 wt% Ni/CeO(2)(75%)-ZrO(2)(25%) was higher than that of the commercial Ni catalyst. Moreover, the catalyst activity was retained due to its excellent resistance to coke deposition even after 5h. The Ni-precursor played a critical role in the catalytic activity. With the exception of nickel nitrate, all the Ni-precursors (chloride and sulfate) caused deactivation of the catalyst.

  12. A cell-to-cell Markovian model for the reliability of a digital control system of a steam generator

    International Nuclear Information System (INIS)

    Gomes, Ian B.; Melo, Paulo F.F. Frutuoso e; Saldanha, Pedro L.C.

    2013-01-01

    With the shift of technology from analog to digital systems, due to the obsolescence of the older analog systems and the functional advantages of the digital ones, existing nuclear power plants have begun to replace their systems, while newer plants use digital systems from the beginning of their construction. However, the process of risk-informed analysis for digital systems has not been satisfactorily developed yet. Traditional methods, such as fault trees, have limitations, while dynamic methods are still in the tests stage and may be difficult to be applied to a real size probabilistic safety assessment (PSA) model. The objective of this paper is to study and obtain a better comprehension of the Markov/CCMT method, a method that combines the traditional Markovian methodology with the cell-to-cell mapping technique for representing the possible failure events that can be originated in the dynamic interactions between the instrumentation and control system and the controlled process, and among the various components of the digital system. The study consists of the simulation of a digital water level control system of the steam generator of a PWR plant. From this simulation, a Failure Modes and Effects Analysis (FMEA) was made and the information obtained was used to calculate the system reliability, using the Markov/CCMT methodology. The results show that the method is capable of identifying the most probable causes for a possible failure of the digital system. (author)

  13. Syngas suitability for solid oxide fuel cells applications produced via biomass steam gasification process: Experimental and modeling analysis

    Science.gov (United States)

    Pieratti, Elisa; Baratieri, Marco; Ceschini, Sergio; Tognana, Lorenzo; Baggio, Paolo

    The technologies and the processes for the use of biomass as an energy source are not always environmental friendly. It is worth to develop approaches aimed at a more sustainable exploitation of biomass, avoiding whenever possible direct combustion and rather pursuing fuel upgrade paths, also considering direct conversion to electricity through fuel cells. In this context, it is of particular interest the development of the biomass gasification technology for synthesis gas (i.e., syngas) production, and the utilization of the obtained gas in fuel cells systems, in order to generate energy from renewable resources. Among the different kind of fuel cells, SOFCs (solid oxide fuel cells), which can be fed with different type of fuels, seem to be also suitable for this type of gaseous fuel. In this work, the syngas composition produced by means of a continuous biomass steam gasifier (fixed bed) has been characterized. The hydrogen concentration in the syngas is around 60%. The system is equipped with a catalytic filter for syngas purification and some preliminary tests coupling the system with a SOFCs stack are shown. The data on the syngas composition and temperature profile measured during the experimental activity have been used to calibrate a 2-dimensional thermodynamic equilibrium model.

  14. Measurement of flow by-passing and turbulent mixing in a model of a fast-reactor steam generator

    International Nuclear Information System (INIS)

    Little, A.J.; Fallows, T.; Central Electricity Generating Board, Leatherhead

    1989-01-01

    A description is given of measurements of edge by-pass velocities and turbulent mixing in a model of a fast reactor steam generator. The velocity measurements were carried out using a DANTEC triple-split fibre probe which allowed both the speed and flow angle of a velocity vector to be measured in a plane normal to the axis of the probe. The measurements revealed the presence of reverse flows in the by-pass and adjacent in-bank channels downstream of a grid plate. The magnitude of the by-pass flow was reduced considerably by the insertion of a kicker grid at the mid point between grid plates. Turbulent mixing measurements revealed that circumferential mixing in channels near the by-pass channel was up to 5 times greater than the radial mixing. The level of radial mixing at the edge of the bank was similar to that measured near the centre of the bank. A method of transposing mass diffusion measurements in air to thermal diffusivities of sodium is discussed. (orig.)

  15. Probability of pregnancy after sterilization: a comparison of hysteroscopic versus laparoscopic sterilization.

    Science.gov (United States)

    Gariepy, Aileen M; Creinin, Mitchell D; Smith, Kenneth J; Xu, Xiao

    2014-08-01

    To compare the expected probability of pregnancy after hysteroscopic versus laparoscopic sterilization based on available data using decision analysis. We developed an evidence-based Markov model to estimate the probability of pregnancy over 10 years after three different female sterilization procedures: hysteroscopic, laparoscopic silicone rubber band application and laparoscopic bipolar coagulation. Parameter estimates for procedure success, probability of completing follow-up testing and risk of pregnancy after different sterilization procedures were obtained from published sources. In the base case analysis at all points in time after the sterilization procedure, the initial and cumulative risk of pregnancy after sterilization is higher in women opting for hysteroscopic than either laparoscopic band or bipolar sterilization. The expected pregnancy rates per 1000 women at 1 year are 57, 7 and 3 for hysteroscopic sterilization, laparoscopic silicone rubber band application and laparoscopic bipolar coagulation, respectively. At 10 years, the cumulative pregnancy rates per 1000 women are 96, 24 and 30, respectively. Sensitivity analyses suggest that the three procedures would have an equivalent pregnancy risk of approximately 80 per 1000 women at 10 years if the probability of successful laparoscopic (band or bipolar) sterilization drops below 90% and successful coil placement on first hysteroscopic attempt increases to 98% or if the probability of undergoing a hysterosalpingogram increases to 100%. Based on available data, the expected population risk of pregnancy is higher after hysteroscopic than laparoscopic sterilization. Consistent with existing contraceptive classification, future characterization of hysteroscopic sterilization should distinguish "perfect" and "typical" use failure rates. Pregnancy probability at 1 year and over 10 years is expected to be higher in women having hysteroscopic as compared to laparoscopic sterilization. Copyright © 2014

  16. Colorimetric Models Used for Establishing the Optimal Dose for Sterilizing the Sea Buck thorn (Hippophae rhamnoides) Leaves Powder with Ionizing Radiation

    International Nuclear Information System (INIS)

    Minea, R.; Popescu, M.I.; Dumitrascu, M.; Sima, E.; Mitru, E.; Manea, St.; Mazilu, S.

    2009-01-01

    The current work intends to promote the development of the methods for establishing the degree of sterilization with ionizing radiations of the herbs in order to use them for obtaining food supplements, but also to obtaining medicines and cosmetic products. Obtaining the raw material, Sea Buckthorn (Hippophae rhamnoides) leaves, at a high level of sterilization without influencing the quality of active principles, is a desideratum of the economic agents in the area. The employed colorimetric methods have practically no impact on the studied herbs and, in the same time, they provide complex information on the effect of the ionizing radiations. The colorimetric methods allow to develop some models to be used both in the indirect evaluation of the microbial charge, before and after the treatment with ionizing radiations and for establishing the optimal necessary dose. The trials were made on Sea Buckthorn (Hippophae rhamnoides) leaves powder supplied by S.C. HOFIGAL EXPORT-IMPORT S.A. from Bucharest. The validation of the obtained colorimetric model was made through some spectrometric setups from the UV-Vis area, on the contents in: polyphenol carboxylic acids, flavones derivates, redox enzymes of superoxide dismutase type, and in the antioxidant activity

  17. Radiation sterilization of medical devices

    International Nuclear Information System (INIS)

    Kaluska, I.; Stuglik, Z.

    1996-01-01

    Overview of sterilization methods of medical devices has been given, with the special stress put on radiation sterilization. A typical validation program for radiation sterilization has been shown and also a comparison of European and ISO standards concerning radiation sterilization has been discussed. (author). 13 refs, 1 fig., 2 tabs

  18. Steam Digest 2001

    Energy Technology Data Exchange (ETDEWEB)

    2002-01-01

    Steam Digest 2001 chronicles BestPractices Program's contributions to the industrial trade press for 2001, and presents articles that cover technical, financial and managerial aspects of steam optimization.

  19. Hysteroscopic Tubal Sterilization

    Science.gov (United States)

    McMartin, K

    2013-01-01

    Background Hysteroscopic tubal sterilization is a minimally invasive alternative to laparoscopic tubal ligation for women who want permanent contraception. The procedures involves non-surgical placement of permanent microinserts into both fallopian tubes. Patients must use alternative contraception for at least 3 months postprocedure until tubal occlusion is confirmed. Compared to tubal ligation, potential advantages of the hysteroscopic procedure are that it can be performed in 10 minutes in an office setting without the use of general or even local anesthesia. Objective The objective of this analysis was to determine the effectiveness and safety of hysteroscopic tubal sterilization compared with tubal ligation for permanent female sterilization. Data Sources A standard systematic literature search was conducted for studies published from January 1, 2008, until December 11, 2012. Review Methods Observational studies, randomized controlled trials (RCTs), systematic reviews and meta-analyses with 1 month or more of follow-up were examined. Outcomes included failure/pregnancy rates, adverse events, and patient satisfaction. Results No RCTs were identified. Two systematic reviews covered 22 observational studies of hysteroscopic sterilization. Only 1 (N = 93) of these 22 studies compared hysteroscopic sterilization to laparoscopic tubal ligation. Two other noncomparative case series not included in the systematic reviews were also identified. In the absence of comparative studies, data on tubal ligation were derived for this analysis from the CREST study, a large, multicentre, prospective, noncomparative observational study in the United States (GRADE low). Overall, hysteroscopic sterilization is associated with lower pregnancy rates and lower complication rates compared to tubal ligation. No deaths have been reported for hysteroscopic sterilization. Limitations A lack of long-term follow-up for hysteroscopic sterilization and a paucity of studies that directly

  20. Steam plant: Steam turbines for combined cycles

    Science.gov (United States)

    Schrieken, J.

    Parameters affecting steam turbines design are discussed and it is concluded that steam turbines for combined cycles are suitable for: powers between 1 and 250 MW; driving a generator, via a gearbox if necessary; drive through of powers which can be up to three times their own power; and ground level installation with up, side, or axial exhaust for condensing turbine applications. Parameters affecting the steam turbine performance are discussed: inlet conditions and flows, sliding inlet conditions, reheat cycles, fired and unfired heat recovery steam generators, cogeneration systems, and combined cycle for process steam supply. Aerodynamic design aspects of steam turbines for combined cycles are discussed. It is concluded that steam turbines for combined cycles have a large range of special requirements. Some typical aspects are: large exhaust annular areas and special exhaust arrangements for condensing steam turbines, drive through of the power of the gas turbines, high influence on the total cycle performance optimization, and a wide variety of extraction systems for cogeneration.

  1. Sterilization: A Review and Update.

    Science.gov (United States)

    Moss, Chailee; Isley, Michelle M

    2015-12-01

    Sterilization is a frequently used method of contraception. Female sterilization is performed 3 times more frequently than male sterilization, and it can be performed immediately postpartum or as an interval procedure. Methods include mechanical occlusion, coagulation, or tubal excision. Female sterilization can be performed using an abdominal approach, or via laparoscopy or hysteroscopy. When an abdominal approach or laparoscopy is used, sterilization occurs immediately. When hysteroscopy is used, tubal occlusion occurs over time, and additional testing is needed to confirm tubal occlusion. Comprehensive counseling about sterilization should include discussion about male sterilization (vasectomy) and long-acting reversible contraceptive methods. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Effects of Secondary Circuit Modeling on Results of Pressurized Water Reactor Main Steam Line Break Benchmark Calculations with New Coupled Code TRAB-3D/SMABRE

    International Nuclear Information System (INIS)

    Daavittila, Antti; Haemaelaeinen, Anitta; Kyrki-Rajamaeki, Riitta

    2003-01-01

    All of the three exercises of the Organization for Economic Cooperation and Development/Nuclear Regulatory Commission pressurized water reactor main steam line break (PWR MSLB) benchmark were calculated at VTT, the Technical Research Centre of Finland. For the first exercise, the plant simulation with point-kinetic neutronics, the thermal-hydraulics code SMABRE was used. The second exercise was calculated with the three-dimensional reactor dynamics code TRAB-3D, and the third exercise with the combination TRAB-3D/SMABRE. VTT has over ten years' experience of coupling neutronic and thermal-hydraulic codes, but this benchmark was the first time these two codes, both developed at VTT, were coupled together. The coupled code system is fast and efficient; the total computation time of the 100-s transient in the third exercise was 16 min on a modern UNIX workstation. The results of all the exercises are similar to those of the other participants. In order to demonstrate the effect of secondary circuit modeling on the results, three different cases were calculated. In case 1 there is no phase separation in the steam lines and no flow reversal in the aspirator. In case 2 the flow reversal in the aspirator is allowed, but there is no phase separation in the steam lines. Finally, in case 3 the drift-flux model is used for the phase separation in the steam lines, but the aspirator flow reversal is not allowed. With these two modeling variations, it is possible to cover a remarkably broad range of results. The maximum power level reached after the reactor trip varies from 534 to 904 MW, the range of the time of the power maximum being close to 30 s. Compared to the total calculated transient time of 100 s, the effect of the secondary side modeling is extremely important

  3. Steam generator leak detection using acoustic method

    International Nuclear Information System (INIS)

    Goluchko, V.V.; Sokolov, B.M.; Bulanov, A.N.

    1982-05-01

    The main requirements to meet by a device for leak detection in sodium - water steam generators are determined. The potentialities of instrumentation designed based on the developed requirements have been tested using a model of a 550 kw steam generator [fr

  4. LMR steam generator blowdown with RETRAN

    International Nuclear Information System (INIS)

    Wei, T.Y.C.

    1985-01-01

    One of the transients being considered in the FSAR Chapter 15 analyses of anticipated LMR transients is the fast blowdown of a steam generator upon inadvertent actuation of the liquid metal/water reaction mitigation system. For the blowdown analysis, a stand-alone steam generator model for the IFR plant was constructed using RETRAN

  5. Steam Digest: Volume IV

    Energy Technology Data Exchange (ETDEWEB)

    2004-07-01

    This edition of the Steam Digest is a compendium of 2003 articles on the technical and financial benefits of steam efficiency, presented by the stakeholders of the U.S. Department of Energy's BestPractices Steam effort.

  6. Steam Digest Volume IV

    Energy Technology Data Exchange (ETDEWEB)

    None

    2004-07-01

    This edition of the Steam Digest is a compendium of 2003 articles on the technical and financial benefits of steam efficiency, presented by the stakeholders of the U.S. Department of Energy's BestPractices Steam effort.

  7. Modeling and 3D-simulation of hydrogen production via methanol steam reforming in copper-coated channels of a mini reformer

    Science.gov (United States)

    Sari, Ataallah; Sabziani, Javad

    2017-06-01

    Modeling and CFD simulation of a three-dimensional microreactor includes thirteen structured parallel channels is performed to study the hydrogen production via methanol steam reforming reaction over a Cu/ZnO/Al2O3 catalyst. The well-known Langmuir-Hinshelwood macro kinetic rate expressions reported by Peppley and coworkers [49] are considered to model the methanol steam reforming reactions. The effects of inlet steam to methanol ratio, pre-heat temperature, channels geometry and size, and the level of external heat flux on the hydrogen quality and quantity (i.e., hydrogen flow rate and CO concentration) are investigated. Moreover, the possibility of reducing the CO concentration by passing the reactor effluent through a water gas shift channel placed in series with the methanol reformer is studied. Afterwards, the simulation results are compared with the experimental data reported in the literature considering two different approaches of mixture-averaged and Maxwell-Stefan formulations to evaluate the diffusive flux of mass. The results indicate that the predictions of the Maxwell-Stefan model is in better agreement with experimental data than mixture-averaged one, especially at the lower feed flow rates.

  8. Gas-Cooled Reactor Programs annual progress report for period ending December 31, 1973. [HTGR fuel reprocessing, fuel fabrication, fuel irradiation, core materials, and fission product distribution; GCFR fuel irradiation and steam generator modeling

    Energy Technology Data Exchange (ETDEWEB)

    Kasten, P.R.; Coobs, J.H.; Lotts, A.L.

    1976-04-01

    Progress is summarized in studies relating to HTGR fuel reprocessing, refabrication, and recycle; HTGR fuel materials development and performance testing; HTGR PCRV development; HTGR materials investigations; HTGR fuel chemistry; HTGR safety studies; and GCFR irradiation experiments and steam generator modeling.

  9. Estimation of effects of photosynthesis response functions on rice yields and seasonal variation of CO2 fixation using a photosynthesis-sterility type of crop yield model

    International Nuclear Information System (INIS)

    Kaneko, D.; Moriwaki, Y.

    2008-01-01

    This study presents a crop production model improvement: the previously adopted Michaelis-Menten (MM) type photosynthesis response function (fsub(rad-MM)) was replaced with a Prioul-Chartier (PC) type function (fsub(rad-PC)). The authors' analysis reflects concerns regarding the background effect of global warming, under simultaneous conditions of high air temperature and strong solar radiation. The MM type function fsub(rad-MM) can give excessive values leading to an overestimate of photosynthesis rate (PSN) and grain yield for paddy-rice. The MM model is applicable to many plants whose (PSN) increases concomitant with increased insolation: wheat, maize, soybean, etc. For paddy rice, the PSN apparently shows a maximum PSN. This paper proves that the MM model overestimated the PSN for paddy rice for sufficient solar radiation: the PSN using the PC model yields 10% lower values. However, the unit crop production index (CPIsub(U)) is almost independent of the MM and PC models because of respective standardization of both PSN and crop production index using average PSNsub(0) and CPIsub(0). The authors improved the estimation method using a photosynthesis-and-sterility based crop situation index (CSIsub(E)) to produce a crop yield index (CYIsub(E)), which is used to estimate rice yields in place of the crop situation index (CSI); the CSI gives a percentage of rice yields compared to normal annual production. The model calculates PSN including biomass effects, low-temperature sterility, and high-temperature injury by incorporating insolation, effective air temperature, the normalized difference vegetation index (NDVI), and effects of temperature on photosynthesis. Based on routine observation data, the method enables automated crop-production monitoring in remote regions without special observations. This method can quantify grain production early to raise an alarm in Southeast Asian countries, which must confront climate fluctuation through this era of global

  10. Cosmological and astrophysical implications of sterile neutrinos

    Science.gov (United States)

    Petraki, Kalliopi

    The discovery of neutrino masses suggests that the Standard Model should be supplemented with new gauge-singlet fermions, often called sterile neutrinos. The interplay among the new couplings introduced in the Standard Model can accommodate the neutrino oscillation data for a variety of choices: the new particles can be extremely heavy and practically unobservable, or they can be light, in which case they can solve several long-standing puzzles. It has been shown, for example, that sterile neutrinos in some range of masses can account for dark matter, their emission from a supernova can explain pulsar kicks, arid their decays can play an important role in the formation of the first stars. Though indirect, these clues indicate that sterile neutrinos can be the minimal solution to a variety of unsolved problems. This emphasizes the importance of investigating further the consequences of these new degrees of freedom for cosmology and astrophysics. In this dissertation, I explore the possible role of sterile neutrinos of different mass scales in some cosmological and astrophysical phenomena. A minimal extension of the Higgs sector of the Standard Model, with a gauge- singlet boson coupled to sterile neutrinos, can provide a consistent framework for the theory of neutrino masses, and can produce a relic population of keV sterile neutrinos via decays of the singlet Higgs. The latter can account for the dark matter of the universe. The mechanism operates around the electroweak scale, and has interesting consequences for the electroweak phase transition. Relic sterile neutrinos produced via decays at the electroweak scale constitute colder dark matter than those produced via other previously suggested mechanisms. The primordial thermal content of dark matter has important implications for the formation of cosmic structures, such as clusters and galaxies. The assessment of the relevant properties suggests that sterile neutrinos produced at the electroweak scale are a

  11. Model tests of a once-through steam generator for land-blocker assessment and THEDA code verification. Final report

    International Nuclear Information System (INIS)

    Carter, H.R.; Childerson, M.T.; Moskal, T.E.

    1983-06-01

    The Babcock and Wilcox Company (B and W) operating Once-Through Steam Generators (OTSGs) have experienced leaking tubes in a region adjacent to the untubed inspection lane. The tube leaks have been attributed to an environmentally-assisted fatigue mechanism with moisture transported up the inspection lane being a major factor in the tube-failure process. B and W has developed a hardware modification (lane blockers) to mitigate the detrimental effects of inspection lane moisture. A 30-tube Laboratory Once-through Steam Generator (Designated OTSGC) was designed, fabricated, and tested. Tests were performed with and without five flat-plate lane blockers installed on tube-support plates (TSPs) 10, 11, 12, 13, and 14. The test results were utilized to determine the effectiveness of lane blockers for eliminating moisture transport to the upper tubesheet in the inspection lanes and to benchmark the predictive capabilities of a three-dimensional steam-generator computer code, THEDA

  12. Voluntary sterilization in Britain.

    Science.gov (United States)

    Jackson, L N

    1968-01-01

    Only recently has the value and importance of sterilization as an effective method of birth control come to be widely recognized in Britian. Credit for this recognition is largely due to the initiative of Dr. C. P. Blacker, chairman of the Simon Population Trust. The Trust's sterilization project was conceived by him and, heralded by an article in The Lancet on 30 April 1966, was launched at a press conference in London in May of that year. Since then the Project has gone from strength to strength. It first function was to make known how voluntary sterilization can help to solve or prevent family problems and to facilitate its practice in Britian. The project has also been concerned to correct the erroneous belief, still held by a dwindling number of medical and law persons, that sterilization is against the law. A prerequisite was to enlist cooperative surgeons all over the country, whose names are now being sent on request to family doctors wishing to refer men for sterilization. The project is concerned mainly with male, rather than female, sterilization. The reason for this is that, when the relative simplicity of vasectomy as compared with tubal ligation is explained to them most couples choose vasectomy. Information about sterilization is supplied not only to applicants but also to university and hospital authorities, surgeons, health and welfare workers, family planning clinics. Forms of consent are provided for the couple concerned, and a follow-up inquiry is being conducted on a substantial scale among men who have been sterilized through the agency of the Project. Though this inquiry is far from complete, replies so far received indicate almost universal satisfaction with the results of the operation. Indeed, with the fear of unwanted pregnancies removed, many couples report that marital harmony is increased. It is known that at least 2000 men have already been sterilized through the mediation of this Project and, as family doctors become increasingly

  13. Status on the Component Models Developed in the Modelica Framework: High-Temperature Steam Electrolysis Plant & Gas Turbine Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Suk Kim, Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); McKellar, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bragg-Sitton, Shannon M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boardman, Richard D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-10-01

    This report has been prepared as part of an effort to design and build a modeling and simulation (M&S) framework to assess the economic viability of a nuclear-renewable hybrid energy system (N-R HES). In order to facilitate dynamic M&S of such an integrated system, research groups in multiple national laboratories have been developing various subsystems as dynamic physics-based components using the Modelica programming language. In fiscal year (FY) 2015, Idaho National Laboratory (INL) performed a dynamic analysis of two region-specific N-R HES configurations, including the gas-to-liquid (natural gas to Fischer-Tropsch synthetic fuel) and brackish water reverse osmosis desalination plants as industrial processes. In FY 2016, INL has developed two additional subsystems in the Modelica framework: a high-temperature steam electrolysis (HTSE) plant and a gas turbine power plant (GTPP). HTSE has been proposed as a high priority industrial process to be integrated with a light water reactor (LWR) in an N-R HES. This integrated energy system would be capable of dynamically apportioning thermal and electrical energy (1) to provide responsive generation to the power grid and (2) to produce alternative industrial products (i.e., hydrogen and oxygen) without generating any greenhouse gases. A dynamic performance analysis of the LWR/HTSE integration case was carried out to evaluate the technical feasibility (load-following capability) and safety of such a system operating under highly variable conditions requiring flexible output. To support the dynamic analysis, the detailed dynamic model and control design of the HTSE process, which employs solid oxide electrolysis cells, have been developed to predict the process behavior over a large range of operating conditions. As first-generation N-R HES technology will be based on LWRs, which provide thermal energy at a relatively low temperature, complementary temperature-boosting technology was suggested for integration with the

  14. An expert system for modelling operators' behaviour in control of a steam generator

    International Nuclear Information System (INIS)

    Cacciabue, P.C.; Guida, G.; Pace, A.

    1987-01-01

    Modelling the mental processes of an operator in charge of controlling a complex industrial plant is a challenging issue currently tackled by several research projects both in the area of artificial intelligence and cognitive psychology. Progress in this field could greatly contribute not only to a deeper understanding of operator's behaviour, but also to the design of intelligent operator support systems. In this paper the authors report the preliminary results of an experimental research effort devoted to model the behaviour of a plant operator by means of Knowledge-based techniques. The main standpoints of their work is that the cognitive processes underlying operator's behaviour can be of three main different types, according to the actual situation where the operator works. In normal situations, or during training sessions, the operator is free to develop deep reasoning, using knowledge about plant structure and function and relying on the first physical principles that govern its behaviour

  15. VERA-CS Modeling and Simulation of PWR Main Steam Line Break Core Response to DNB

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K [ORNL; Sung, Yixing [Westinghouse Electric Company, Cranberry Township; Kucukboyaci, Vefa [Westinghouse Electric Company, Cranberry Township; Xu, Yiban [Westinghouse Electric Company, Cranberry Township; Cao, Liping [Westinghouse Electric Company, Cranberry Township

    2016-01-01

    The Virtual Environment for Reactor Applications core simulator (VERA-CS) being developed by the Consortium for the Advanced Simulation of Light Water Reactors (CASL) includes coupled neutronics, thermal-hydraulics, and fuel temperature components with an isotopic depletion capability. The neutronics capability employed is based on MPACT, a three-dimensional (3-D) whole core transport code. The thermal-hydraulics and fuel temperature models are provided by the COBRA-TF (CTF) subchannel code. As part of the CASL development program, the VERA-CS (MPACT/CTF) code system was applied to model and simulate reactor core response with respect to departure from nucleate boiling ratio (DNBR) at the limiting time step of a postulated pressurized water reactor (PWR) main steamline break (MSLB) event initiated at the hot zero power (HZP), either with offsite power available and the reactor coolant pumps in operation (high-flow case) or without offsite power where the reactor core is cooled through natural circulation (low-flow case). The VERA-CS simulation was based on core boundary conditions from the RETRAN-02 system transient calculations and STAR-CCM+ computational fluid dynamics (CFD) core inlet distribution calculations. The evaluation indicated that the VERA-CS code system is capable of modeling and simulating quasi-steady state reactor core response under the steamline break (SLB) accident condition, the results are insensitive to uncertainties in the inlet flow distributions from the CFD simulations, and the high-flow case is more DNB limiting than the low-flow case.

  16. Two-phase flow dynamics in a model steam generator under vertical acceleration oscillation field

    International Nuclear Information System (INIS)

    Ishida, T.; Teshima, N.; Sakurai, S.

    1992-01-01

    The influence of periodically varying acceleration on hydrodynamic response has been studied experimentally using an experimental rig which models a marine reactor subject to vertical motion. The effect on the primary loop is small, but the effect on the secondary loop is large. The variables of the secondary loop, such as circulation flow rate and water level, oscillate with acceleration. The variation of gains in frequency response is analysed. The variations of flow in the secondary loop and in the downcome water level, increase in proportion to the acceleration. The effect of the flow resistance in the secondary loop on the two-phase flow dynamics is clarified. (7 figures) (Author)

  17. Sterility Maintenance Assessment of Moist/Wet Material After Steam Sterilization and 30-day Storage Evaluación de la manutención de la esterilidad de materiales húmedos/mojados después de esterilizados con vapor y almacenados por 30 días Avaliação da manutenção da esterilidade de materiais úmidos/molhados após a esterilização por vapor e armazenamento por 30 dias

    Directory of Open Access Journals (Sweden)

    Giovana Abrahão de Araújo Moriya

    2010-08-01

    Full Text Available Moist/wet materials stored after autoclaving are considered contaminated and not recommended for use. This study evaluates the maintenance of sterility in moist/wet material after being submitted to steam sterilization and stored for a period of 30 days. Aiming to support decision-making in emergency situations, 40 surgical boxes packed in nonwoven cloth covering Spunbound, Metblouwn, Spunbound (SMS: half (the experimental group were placed in an autoclave but the drying phase was interrupted, yielding moist/wet materials and the other half (the negative control group underwent the complete cycle. The external parts of each surgical box were deliberately contaminated with Serratia marcescens and subsequently stored for 30 days. After this period, the boxes' contents were submitted to sterility tests and no growth was observed. The presence of moisture inside the surgical boxes did not interfere with maintaining their sterility.Se consideran como contaminados los objetos mojados/húmedos almacenados después de ser esterilizados en autoclave, no siendo recomendados para uso. El objetivo del estudio fue evaluar la manutención de la esterilidad de los materiales mojados/húmedos después de sometidos al proceso de esterilización por vapor y almacenados por un intervalo de 30 días. Con la finalidad de auxiliar en la toma de decisiones en situaciones de emergencia, fueron preparadas 40 cajas quirúrgicas embaladas en SMS, siendo la mitad (experimental sometidas a un proceso de esterilización en autoclave, con fase de secado interrumpida, liberando material mojado/húmedo y otras 20 (control con el ciclo completo. Las partes externas de cada caja fueron intencionalmente contaminadas con Serratia marcescens y posteriormente almacenadas por 30 días. Después ese período, los contenidos de las cajas fueron sometidos a pruebas de esterilidad, acusando ausencia total de crecimiento. La presencia de humedad dentro de las cajas no interfirió en la

  18. Bactericidal activity does not predict sterilizing activity: the case of rifapentine in the murine model of Mycobacterium ulcerans disease.

    Directory of Open Access Journals (Sweden)

    Deepak V Almeida

    Full Text Available Since 2004, treatment of Mycobacterium ulcerans disease, or Buruli ulcer, has shifted from surgery to daily treatment with streptomycin (STR + rifampin (RIF for 8 weeks. For shortening treatment duration, we tested the potential of daily rifapentine (RPT, a long-acting rifamycin derivative, as a substitute for RIF.BALB/c mice were infected with M. ulcerans in the right hind footpad and treated either daily (7/7 with STR+RIF or five days/week (5/7 with STR+RIF or STR+RPT for 4 weeks, beginning 28 days after infection when CFU counts were 4.88±0.51. The relative efficacy of the drug treatments was compared by footpad CFU counts during treatment and median time to footpad swelling after treatment cessation as measure of sterilizing activity. All drug treatments were bactericidal. After 1 week of treatment, the decline in CFU counts was significantly greater in treated mice but not different between the three treated groups. After 2 weeks of treatment, the decline in CFU was greater in mice treated with STR+RPT 5/7 than in mice treated with STR+RIF 7/7 and STR+RIF 5/7. After 3 and 4 weeks of treatment, CFU counts were nil in mice treated with STR+RPT and reduced by more than 3 and 4 logs in mice treated with STR+RIF 5/7 and STR+RIF 7/7, respectively. In sharp contrast to the bactericidal activity, the sterilizing activity was not different between all drug regimens although it was in proportion to the treatment duration.The better bactericidal activity of daily STR+RIF and especially of STR+RPT did not translate into better prevention of relapse, possibly because relapse-freecure after treatment of Buruli ulcer is more related to the reversal of mycolactone-induced local immunodeficiency by drug treatment rather than to the bactericidal potency of drugs.

  19. Audits of radiation sterilization facilities

    International Nuclear Information System (INIS)

    Kelkar, Prabhakar M.

    2001-01-01

    Johnson and Johnson is the world leader in sterilization science and technology. A special group of scientists and technologists are engaged in the development of new methods of sterilization, worldwide monitoring of sterilization processes, equipment and approvals for all types of sterilization processes. Kilmer Conference in the alternate year for the benefit of all those involved in improvement in sterilization science is held. Cobalt-60 gamma radiation for sterilization of medical products on commercial scale is used. This kind of mammoth task can only be achieved through systematic method of planning, auditing, expert review and approval of facilities

  20. Steam distillation extraction kinetics regression models to predict essential oil yield, composition, and bioactivity of chamomile oil

    Science.gov (United States)

    Chamomile (Matricaria chamomilla L.) is one of the most widely spread and used medicinal and essential oil crop in the world. Chamomile essential oil is extracted via steam distillation of the inflorescences (flowers). In this study, distillation time (DT) was found to be a crucial determinant of yi...

  1. Experimental and modeling study of high performance direct carbon solid oxide fuel cell with in situ catalytic steam-carbon gasification reaction

    Science.gov (United States)

    Xu, Haoran; Chen, Bin; Zhang, Houcheng; Tan, Peng; Yang, Guangming; Irvine, John T. S.; Ni, Meng

    2018-04-01

    In this paper, 2D models for direct carbon solid oxide fuel cells (DC-SOFCs) with in situ catalytic steam-carbon gasification reaction are developed. The simulation results are found to be in good agreement with experimental data. The performance of DC-SOFCs with and without catalyst are compared at different operating potential, anode inlet gas flow rate and operating temperature. It is found that adding suitable catalyst can significantly speed up the in situ steam-carbon gasification reaction and improve the performance of DC-SOFC with H2O as gasification agent. The potential of syngas and electricity co-generation from the fuel cell is also evaluated, where the composition of H2 and CO in syngas can be adjusted by controlling the anode inlet gas flow rate. In addition, the performance DC-SOFCs and the percentage of fuel in the outlet gas are both increased with increasing operating temperature. At a reduced temperature (below 800 °C), good performance of DC-SOFC can still be obtained with in-situ catalytic carbon gasification by steam. The results of this study form a solid foundation to understand the important effect of catalyst and related operating conditions on H2O-assisted DC-SOFCs.

  2. Influence of sterilization on mechanical properties and fatigue resistance of nickel-titanium rotary endodontic instruments.

    Science.gov (United States)

    Viana, A C D; Gonzalez, B M; Buono, V T L; Bahia, M G A

    2006-09-01

    To evaluate the effect of repeated sterilization cycles in dry oven or autoclave, on the mechanical behaviour and fatigue resistance of rotary endodontic Ni-Ti instruments. New Ni-Ti instruments were subjected to five consecutive sterilization cycles in a dry oven or steam autoclave. Microhardness was measured in the nonmachined parts of the shanks of instruments using a Vickers indenter. Specimens of Ni-Ti wires were submitted to the same sterilization protocol and tensile tested until rupture. A group of instruments were fatigued to one half of their average fatigue life and then sterilized. New and sterilized instruments were fatigue tested until rupture. anova tests at alpha = 0.05 were used for statistical analysis. Sterilization procedures resulted in no significant changes in Vickers microhardness, nor in the parameters describing the mechanical behaviour of the wires. However, the number of cycles to failure was statistically higher for all instruments after dry heat or autoclave sterilization cycles. In the instruments previously fatigued to one half of their fatigue life, autoclave sterilization gave rise to an increase of 39% in the remaining number of cycles to failure. Changes in the mechanical properties of Ni-Ti endodontic instruments after five cycles of commonly used sterilization procedures were insignificant. The sterilization procedures are safe as they produced a significant increase in the fatigue resistance of the instruments.

  3. Sterile Neutrinos in Cold Climates

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Benjamin J.P. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2015-09-01

    Measurements of neutrino oscillations at short baselines contain an intriguing set of experimental anomalies that may be suggestive of new physics such as the existence of sterile neutrinos. This three-part thesis presents research directed towards understanding these anomalies and searching for sterile neutrino oscillations. Part I contains a theoretical discussion of neutrino coherence properties. The open-quantum-system picture of neutrino beams, which allows a rigorous prediction of coherence distances for accelerator neutrinos, is presented. Validity of the standard treatment of active and sterile neutrino oscillations at short baselines is verified, and non-standard coherence loss effects at longer baselines are predicted. Part II concerns liquid argon detector development for the MicroBooNE experiment, which will search for short-baseline oscillations in the Booster Neutrino Beam at Fermilab. Topics include characterization and installation of the MicroBooNE optical system; test-stand measurements of liquid argon optical properties with dissolved impurities; optimization of wavelength-shifting coatings for liquid argon scintillation light detection; testing and deployment of high-voltage surge arrestors to protect TPC field cages; and software development for optical and TPC simulation and reconstruction. Part III presents a search for sterile neutrinos using the IceCube neutrino telescope, which has collected a large sample of atmospheric-neutrino-induced events in the 1-10 TeV energy range. Sterile neutrinos would modify the detected neutrino flux shape via MSW-resonant oscillations. Following a careful treatment of systematic uncertainties in the sample, no evidence for MSW-resonant oscillations is observed, and exclusion limits on 3+1 model parameter space are derived. Under the mixing assumptions made, the 90% confidence level exclusion limit extends to sin224 ≤ 0.02 at m2 ~ 0.3 eV2, and the LSND and Mini

  4. Steam generator tube denting simulation testing

    International Nuclear Information System (INIS)

    Battaglia, P.J.; Singley, W.J.

    1978-02-01

    Tube denting has been reported in steam generators in a number of commercial nuclear power plants in recent years. In order to aid in understanding of the mechanism leading to tube denting in the steam generators, a Bettis laboratory test program was initiated to attempt to reproduce tube denting and to investigate the effects of chemistry, design, and temperature. The results of the tests indicate that denting can be reproduced in the small model steam generator test apparatus devised for this testing. Denting was observed under carbon steel support plates in seawater-contaminated secondary water in a test with hydrazine-ammonia chemistry and a primary water inlet temperature of 590 0 F and in a test with hydrazine-morpholine chemistry and a primary water inlet temperature of 545 0 F. The parameters of these two tests simulate conditions in a typical commercial steam generator and the Shippingport Atomic Power Station steam generators, respectively

  5. Effectiveness of various sterilization methods of contaminated post-fitted molar band

    Directory of Open Access Journals (Sweden)

    Anggia Tridianti

    2013-06-01

    Full Text Available Background: Molar band as anchoring device may be contaminated during the fitting process. Thus, decontamination process is essential to prevent cross-infection between patients. Purpose: The objective of this research was to determine the amount of bacteria in molar band post-fitted on the patient teeth, after previously undergone pre-sterilization using alcohol and ultrasonic cleaning bath followed by sterilization using dry heat oven and steam autoclave, in order to find the best method in decontamination of post-fitted molar band. Methods: Four molar bands which already fitted on one patient then divided evenly into two groups. The first group was pre-sterilized using alcohol. One of the bands then sterilized using dry heat oven, while the other one was sterilized using steam autoclave. The second group was pre-sterilized using ultrasonic cleaning bath. One band from this group then sterilized using dry heat oven and the other was sterilized using steam autoclave. The next step was to immerse all the bands in a phosphate-buffered saline solution. Using micropipette, the solution was retrieved and dropped upon a petri dish containing Brain Heart Infusion broth. The dish was then stored in an incubator for 24 hours, prior to counting the number of bacteria existed. The same methods were used to the rest of the patients, with total 128 molar bands from 32 patients. Results: There was a profound difference in numbers of bacteria found between those methods of sterilization. However, there was a non significant difference between the two groups which were at the alcohol-steam autoclave group and at the ultrasonic cleaning bath-steam autoclave group. Conclusion: This study showed that steam autoclave is better than for sterilizing molar band, as it left the minimal amount of bacteria in post-fitted molar band.Latar belakang: Molar band merupakan suatu alat penjangkaran yang dapat mengalami kontaminasi selama proses fitting band, sehingga perlu

  6. Heat sterilization of wood

    Science.gov (United States)

    Xiping Wang

    2010-01-01

    Two important questions should be considered in heat sterilizing solid wood materials: First, what temperature–time regime is required to kill a particular pest? Second, how much time is required to heat the center of any wood configuration to the kill temperature? The entomology research on the first question has facilitated the development of international standards...

  7. MINOS Sterile Neutrino Search

    Energy Technology Data Exchange (ETDEWEB)

    Koskinen, David Jason [Univ. College London, Bloomsbury (United Kingdom)

    2009-02-01

    The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline accelerator neutrino experiment designed to measure properties of neutrino oscillation. Using a high intensity muon neutrino beam, produced by the Neutrinos at Main Injector (NuMI) complex at Fermilab, MINOS makes two measurements of neutrino interactions. The first measurement is made using the Near Detector situated at Fermilab and the second is made using the Far Detector located in the Soudan Underground laboratory in northern Minnesota. The primary goal of MINOS is to verify, and measure the properties of, neutrino oscillation between the two detectors using the v μ→ Vτ transition. A complementary measurement can be made to search for the existence of sterile neutrinos; an oft theorized, but experimentally unvalidated particle. The following thesis will show the results of a sterile neutrino search using MINOS RunI and RunII data totaling ~2.5 x 1020 protons on target. Due to the theoretical nature of sterile neutrinos, complete formalism that covers transition probabilities for the three known active states with the addition of a sterile state is also presented.

  8. Sterilization of Native Americans

    Science.gov (United States)

    Dillingham, Brint

    1977-01-01

    The U.S. State Department's Agency for International Development (AID) is spending more than $143 million this year for population control measures in over 70 nations around the world and it is estimated that as much as $10 million was spent in one year for surgical sterilization procedures. (JC)

  9. Reliability of Laparoscopic Compared With Hysteroscopic Sterilization at One Year: A Decision Analysis

    Science.gov (United States)

    Gariepy, Aileen M.; Creinin, Mitchell D.; Schwarz, Eleanor B.; Smith, Kenneth J.

    2011-01-01

    OBJECTIVE To estimate the probability of successful sterilization after hysteroscopic or laparoscopic sterilization procedure. METHODS An evidence-based clinical decision analysis using a Markov model was performed to estimate the probability of a successful sterilization procedure using laparoscopic sterilization, hysteroscopic sterilization in the operating room, and hysteroscopic sterilization in the office. Procedure and follow-up testing probabilities for the model were estimated from published sources. RESULTS In the base case analysis, the proportion of women having a successful sterilization procedure on first attempt is 99% for laparoscopic, 88% for hysteroscopic in the operating room and 87% for hysteroscopic in the office. The probability of having a successful sterilization procedure within one year is 99% with laparoscopic, 95% for hysteroscopic in the operating room, and 94% for hysteroscopic in the office. These estimates for hysteroscopic success include approximately 6% of women who attempt hysteroscopically but are ultimately sterilized laparoscopically. Approximately 5% of women who have a failed hysteroscopic attempt decline further sterilization attempts. CONCLUSIONS Women choosing laparoscopic sterilization are more likely than those choosing hysteroscopic sterilization to have a successful sterilization procedure within one year. However, the risk of failed sterilization and subsequent pregnancy must be considered when choosing a method of sterilization. PMID:21775842

  10. Use of Lagrangian transport models and Sterilized High Volume Sampling to pinpoint the source region of Kawasaki disease and determine the etiologic agent

    Science.gov (United States)

    Curcoll Masanes, Roger; Rodó, Xavier; Anton, Jordi; Ballester, Joan; Jornet, Albert; Nofuentes, Manel; Sanchez-Manubens, Judith; Morguí, Josep-Anton

    2015-04-01

    Kawasaki disease (KD) is an acute, coronary artery vasculitis of young children, and still a medical mystery after more than 40 years. A former study [Rodó et al. 2011] demonstrated that certain patterns of winds in the troposphere above the earth's surface flowing from Asia were associated with the times of the annual peak in KD cases and with days having anomalously high numbers of KD patients. In a later study [Rodó et al. 2014], we used residence times from an Air Transport Model to pinpoint the source region for KD. Simulations were generated from locations spanning Japan from days with either high or low KD incidence. In order to cope with stationarity of synoptic situations, only trajectories for the winter months, when there is the maximum in KD cases, were considered. Trajectories traced back in time 10 days for each dataset and location were generated using the flexible particle Lagrangian dispersion model (FLEXPART Version 8.23 [Stohl et al. 2005]) run in backward mode. The particles modeled were air tracers, with 10,000 particles used on each model run. The model output used was residence time, with an output grid of 0.5° latitude × longitude and a time resolution of 3 h. The data input used for the FLEXPART model was gridded atmospheric wind velocity from the European Center for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim at 1°). Aggregates of winter period back-trajectories were calculated for three different regions of Japan. A common source of wind air masses was located for periods with High Kawasaki disease. Knowing the trajectories of winds from the air transport models, a sampling methodology was developed in order to capture the possible etiological agent or other tracers that could have been released together. This methodology is based on the sterilized filtering of high volumes of the transported air at medium tropospheric levels by aircraft sampling and a later analyze these filters with adequate techniques. High purity

  11. Obstetric Outcomes After Failed Hysteroscopic and Laparoscopic Sterilization Procedures.

    Science.gov (United States)

    Brandi, Kristyn; Morgan, Jake R; Paasche-Orlow, Michael K; Perkins, Rebecca B; White, Katharine OʼConnell

    2018-02-01

    To compare obstetric outcomes after failed hysteroscopic and laparoscopic sterilization. This retrospective cohort study examined pregnancy outcomes including live birth, preterm birth, stillbirth, spontaneous abortion, therapeutic abortion, ectopic pregnancies, and gestational trophoblastic disease using a commercial claims administrative database for the years 2007-2013. We used a Z-test to compare pregnancy outcomes per 100 person-years based on type of sterilization. Cox proportional hazard models controlled for patient age, geographic region, urbanicity, comorbidities, and insurance type. We evaluated 997 pregnancy outcomes among 817 women from a total of 70,115 women with a history of either hysteroscopic sterilization (n=387 pregnancies/27,724 cases) or laparoscopic sterilization (n=610 pregnancies/42,391 cases). Women undergoing hysteroscopic sterilization were slightly older than, but otherwise similar to, women undergoing laparoscopic sterilization. The most common outcome was live birth, which was more likely after hysteroscopic sterilization compared with laparoscopic sterilization (adjusted hazard ratio 1.32, 95% CI 1.09-1.60). The rate of spontaneous abortion was not statistically significantly different between the two groups. Therapeutic abortion occurred more often after hysteroscopic sterilization (adjusted hazard ratio 1.49, 95% CI 1.10-2.01), whereas ectopic pregnancies occurred less often (adjusted hazard ratio 0.12, 95% CI 0.05-0.29) compared with laparoscopic sterilization. Hysteroscopic sterilization is associated with higher rates of live birth and lower rates of ectopic pregnancy compared with laparoscopic sterilization. Spontaneous abortion and preterm birth rates were similar in both groups. These data do not support an adverse effect of hysteroscopic sterilization on subsequent pregnancy outcomes.

  12. Modelling and simulation of the steam line, the high and low pressure turbines and the pressure regulator for the SUN-RAH nucleo electric university simulator

    International Nuclear Information System (INIS)

    Lopez R, A.

    2003-01-01

    In the following article the development of a simulator that allows to represent the dynamics of the following systems: steam line, nozzle, vapor separator, reheater, high pressure turbine, low pressure turbine, power generator and the pressure regulator of a nucleo electric power station. We start from the supposition that this plant will be modeled from a nuclear reactor type BWR (Boiling Water Reactor), using models of reduced order that represent the more important dynamic variables of the physical processes that happen along the steam line until the one generator. To be able to carry out the simulation in real time the Mat lab mathematical modeling software is used, as well as the specific simulation tool Simulink. It is necessary to point out that the platform on which the one is executed the simulator is the Windows operating system, to allow the intuitive use that only this operating system offers. The above-mentioned obeys to that the objective of the simulator it is to help the user to understand some of the dynamic phenomena that are present in the systems of a nuclear plant, and to provide a tool of analysis and measurement of variables to predict the desirable behavior of the same ones. The model of a pressure controller for the steam lines, the high pressure turbine and the low pressure turbine is also presented that it will be the one in charge of regulating the demand of the system according to the characteristics and critic restrictions of safety and control, assigned according to those wanted parameters of performance of this system inside the nucleo electric plant. This simulator is totally well defined and it is part of the University student nucleo electric simulator with Boiling Water Reactor (SUN-RAH), an integral project and of greater capacity. (Author)

  13. Steam torch plasma modelling

    Czech Academy of Sciences Publication Activity Database

    Jeništa, Jiří

    2017-01-01

    Roč. 37, č. 3 (2017), s. 653-687 ISSN 0272-4324 R&D Projects: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : Arc * Evaporation * Mass flow rate * Water-vortex stabilization * Net emission coefficients * Partial characteristics * Local thermodynamic equilibrium Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.355, year: 2016 http://link.springer.com/article/10.1007/s11090-017-9789-7

  14. Spectro colorimetric and GC-MS Models, Used to Determine the Changes in the Natural Compounds of the Sea Buck thorn Leaves Sterilized with Ionizing Radiations

    International Nuclear Information System (INIS)

    Minea, R.; Popescu, M.I.; Sima, E.; Dumitrascu, M.; Culea, M.; Manea, St.; Mazilu, E.

    2009-01-01

    Spectro colorimetric and GC-MS methods were developed for the quantitative and quality analyze of the fatty acid methyl esters (FAME) and of some natural compounds extracted from the Sea Buckthorn (Hippophae rhamnoides) leaves sterilized by treating them with accelerated electron beams, generated by a linear accelerator. The spectro colorimetric models describe and easy controls the color as it relies on the psycho physics of the color perception and on the simple colorimetric models. Hunter Lab, CIELAB, CIELCH simple colorimetric models are used in developing complex colorimetric models and for the calculation of simple colorimetric models expressed as the total color difference between a sample and a witness, ΔΕ * , ΔΕ C MC, ΔΕ * D IN99, ΔΕ * C IE2000. They provide qualitative data on the deterioration of the active compounds by irradiation. If they are validated by GC-MS methods, they can also provide quantitative data on the radioinduced changes caused to the Sea Buckthorn leaves. The developed GC-MS methods allow the validation of the spectro colorimetric methods for the quantitative and qualitative evaluation of the radioinduced changes in the Sea Buckthorn leaves, reducing both the analyze times and the analyze cost, respectively the random errors of the procedures for extraction and derivation applied to samples preparation

  15. Steam gasification of wood biomass in a fluidized biocatalytic system bed gasifier: A model development and validation using experiment and Boubaker Polynomials Expansion Scheme BPES

    Directory of Open Access Journals (Sweden)

    Luigi Vecchione

    2015-07-01

    Full Text Available One of the most important issues in biomass biocatalytic gasification is the correct prediction of gasification products, with particular attention to the Topping Atmosphere Residues (TARs. In this work, performedwithin the European 7FP UNIfHY project, we develops and validate experimentally a model which is able of predicting the outputs,including TARs, of a steam-fluidized bed biomass gasifier. Pine wood was chosen as biomass feedstock: the products obtained in pyrolysis tests are the relevant model input. Hydrodynamics and chemical properties of the reacting system are considered: the hydrodynamic approach is based on the two phase theory of fluidization, meanwhile the chemical model is based on the kinetic equations for the heterogeneous and homogenous reactions. The derived differentials equations for the gasifier at steady state were implemented MATLAB. Solution was consecutively carried out using the Boubaker Polynomials Expansion Scheme by varying steam/biomass ratio (0.5-1 and operating temperature (750-850°C.The comparison between models and experimental results showed that the model is able of predicting gas mole fractions and production rate including most of the representative TARs compounds

  16. Characteristics of steam jet impingement on annulus

    International Nuclear Information System (INIS)

    Yoon, Sang H.; Kim, Won J.; Suh, Kune Y.; Song, Chul H.

    2004-01-01

    The steam jet impingement occurs when the steam through the cold leg from the steam generator strikes the inner reactor barrel during the reflood phase of a loss-of-coolant accident (LOCA), which is a characteristic behavior for the APR1400 (Advanced Power Reactor 1400 MWe). In the cold leg break LOCA, the steam and water flows in the downcomer are truly multidimensional. The azimuthal velocity distribution of the steam flow has an important bearing on the thermal hydraulic phenomena such as the emergency coolant water direct bypass, sweepout, steam condensation, and so forth. The investigation of jet flow is required to determine the steam path and momentum reduction rate after the impingement. For the observation of the steam behavior near the break, the computational fluid dynamic (CFD) analysis has been carried out using CFX5.6. The flow visualization and analysis demonstrate the velocity profiles of the steam flow in the annulus region for the same boundary conditions. Pursuant to the CFD results, the micro-Pitot tubes were positioned at varying angles, and corrected for their sensitivity. The experiments were carried out to directly measure the pressure differential and to visualize the flow utilizing a smoke injection method. Results from this study are slated to be applied to MARS, which is a thermal hydraulic system code for the best-estimate analysis. The current one- or two-dimensional analysis in MARS was known to distort the local flow behavior. To enhance prediction capability of MARS, it is necessary to inspect the steam path in the break flow and mechanically simulate the momentum variation. The present experimental and analytical results can locally be applied to developing the engineering models of specific and essential phenomena. (author)

  17. Unsteady coupling effects of wet steam in steam turbines flows

    International Nuclear Information System (INIS)

    Blondel, Frederic

    2014-01-01

    In addition to conventional turbomachinery problems, both the behavior and performances of steam turbines are highly dependent on the vapour thermodynamic state and the presence of a liquid phase. EDF, the main French electricity producer, is interested in further developing its' modelling capabilities and expertise in this area to allow for operational studies and long-term planning. This PhD thesis explores the modelling of wetness formation and growth in a steam turbine and an analysis of the coupling between the liquid phase and the main flow unsteadiness. To this end, the work in this thesis took the following approach. Wetness was accounted for using a homogeneous model coupled with transport equations to take into account the effects of non-equilibrium phenomena, such as the growth of the liquid phase and nucleation. The real gas attributes of the problem demanded adapted numerical methods. Before their implementation in the 3D elsA solver, the accuracy of the chosen models was tested using a developed one-dimensional nozzle code. In this manner, various condensation models were considered, including both poly-dispersed and monodispersed behaviours of the steam. Finally, unsteady coupling effects were observed from several perspectives (1D, 1D - 3D, 3D), demonstrating the ability of the method of moments to sustain unsteady phenomena which were not apparent in a simple monodispersed model. (author)

  18. Validation of CTF Droplet Entrainment and Annular/Mist Closure Models using Riso Steam/Water Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wysocki, Aaron J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-02-01

    This report summarizes the work done to validate the droplet entrainment and de-entrainment models as well as two-phase closure models in the CTF code by comparison with experimental data obtained at Riso National Laboratory. The Riso data included a series of over 250 steam/water experiments that were performed in both tube and annulus geometries over a range of various pressures and outlet qualities. Experimental conditions were set so that the majority of cases were in the annular/mist ow regime. Measurements included liquid lm ow rate, droplet ow rate, lm thickness, and two-phase pressure drop. CTF was used to model 180 of the tubular geometry cases, matching experimental geometry, outlet pressure, and outlet ow quality to experimental values. CTF results were compared to the experimental data at the outlet of the test section in terms of vapor and entrained liquid ow fractions, pressure drop per unit length, and liquid lm thickness. The entire process of generating CTF input decks, running cases, extracting data, and generating comparison plots was scripted using Python and Matplotlib for a completely automated validation process. All test cases and scripting tools have been committed to the COBRA-TF master repository and selected cases have been added to the continuous testing system to serve as regression tests. The dierences between the CTF- and experimentally-calculated ow fraction values were con- sistent with previous calculations by Wurtz, who applied the same entrainment correlation to the same data. It has been found that CTF's entrainment/de-entrainment predictive capability in the annular/mist ow regime for this particular facility is comparable to the licensed industry code, COBRAG. While lm and droplet predictions are generally good, it has been found that accuracy is diminished at lower ow qualities. This nding is consistent with the noted deciencies in the Wurtz entrainment model employed by CTF. The CTF predicted two-phase pressure drop in

  19. Dark matter relic abundance and light sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Yi-Lei [Center for High Energy Physics,Peking University, Beijing 100871 (China); Zhu, Shou-hua [Center for High Energy Physics,Peking University, Beijing 100871 (China); Institute of Theoretical Physics & State Key Laboratory of Nuclear Physics and Technology,Peking University, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,Beijing 100871 (China)

    2017-01-09

    In this paper, we calculate the relic abundance of the dark matter particles when they can annihilate into sterile neutrinos with the mass ≲100 GeV in a simple model. Unlike the usual standard calculations, the sterile neutrino may fall out of the thermal equilibrium with the thermal bath before the dark matter freezes out. In such a case, if the Yukawa coupling y{sub N} between the Higgs and the sterile neutrino is small, this process gives rise to a larger Ω{sub DM}h{sup 2} so we need a larger coupling between the dark matter and the sterile neutrino for a correct relic abundance.

  20. Sterile neutrino searches via displaced vertices at LHCb

    Science.gov (United States)

    Antusch, Stefan; Cazzato, Eros; Fischer, Oliver

    2017-11-01

    We explore the sensitivity of displaced vertex searches at LHCb for testing sterile neutrino extensions of the Standard Model towards explaining the observed neutrino masses. We derive estimates for the constraints on sterile neutrino parameters from a recently published displaced vertex search at LHCb based on run 1 data. They yield the currently most stringent limit on active-sterile neutrino mixing in the sterile neutrino mass range between 4.5 GeV and 10 GeV. Furthermore, we present forecasts for the sensitivities that could be obtained from the run 2 data and also for the high-luminosity phase of the LHC.

  1. Steam generator tube integrity program

    International Nuclear Information System (INIS)

    Diercks, D.R.; Shack, W.J.

    1996-01-01

    The degradation of steam generator tubes in pressurized water nuclear reactors continues to be a serious problem, and the US Nuclear Regulatory Commission (NRC) is developing a performance-based rule and regulatory guide for steam generator tube integrity. To support the evaluation of industry-proposed implementation of these performance-based criteria, the NRC is sponsoring a new research program at Argonne National Laboratory on steam generator tubing degradation. The objective of the new program is to provide the necessary experimental data and predictive correlations and models that will permit the NRC to independently evaluate the integrity of steam generator tubes. The technical work in the program is divided into four tasks, (1) assessment of inspection reliability, (2) research on in-service inspection technology, (3) research on degradation modes and integrity, and (4) development of methodology and technical assessments for current and emerging regulatory issues. The objectives of and planned research activities under each of these four tasks are described here. (orig.)

  2. 21 CFR 880.6850 - Sterilization wrap.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Sterilization wrap. 880.6850 Section 880.6850 Food... § 880.6850 Sterilization wrap. (a) Identification. A sterilization wrap (pack, sterilization wrapper... sterilized by a health care provider. It is intended to allow sterilization of the enclosed medical device...

  3. Abortion and sterilization.

    Science.gov (United States)

    Steele, S J

    1970-01-01

    This discusses activities current in England under the abortion law of April 1968. In England and Wales in 1969 there were 54,013 recorded abortions and 15 related deaths. Since then both the number of deaths and the number of abortions have been increasing. This abortion increase is partly attributed to the adverse publicity regarding the pill which has caused many women to give up oral contraceptives. Complications have included incomplete removal of the products of conception, sepsis, hemorrhage, and perforation of the uterus. There have been wide variation in interpretations of the law by different hospitals and staffs. Sterilization operations are being done in increasing number for both men and women. Carefully worded consent forms are now in use to insure patient understanding and consent. Psychological changes may follow sterilization, but are relatively uncommon. Physicians should do all possible to help women avoid unwanted pregnancies and thereby reduce the demand for termination.

  4. Evaluation of the effects of fragmented steam exposure cycles on the survival of bacterial spores.

    Science.gov (United States)

    Shirtz, J T; Soli, T C; Allen, W E; Stellwag, E J; McConnell, T J

    1999-01-01

    The purpose of this study was to examine the population and resistance characteristics of bacterial spores which have been exposed to an abbreviated steam sterilization cycle. The philosophy of many pharmaceutical manufacturers is to require a second complete terminal sterilization cycle in the event of an unplanned interruption during the terminal sterilization of a production batch. The impact of abbreviated steam sterilization cycles was examined for their effect on the survivability and resistance of bacterial spores following an inadequate sterilization cycle. Steam sterilization cycles of two minutes and four minutes were performed on separate groups of Biological Indicator spore strips. These groups were then held at room temperature and re-exposed to a range of sterilization conditions after 24, 48, and 72 hours, i.e., start cycle, abort, hold, start cycle, abort. Spore survivor curves were calculated and resistance estimations were determined. The results of the study indicated that the log level of the surviving spores remained fairly constant, but variability within groups increased as sterilization time increased. The resistance of these surviving spores, as measured by D value, also remained relatively constant throughout the holding period. Abbreviated cycles were similarly conducted on ampules containing a spore suspension, and the spore populations and moist heat resistances were determined over time. Contrary to the spore strip, the population of the subject ampules was less stable showing a gradual decline over the same observation period. The study also included a comparison of the surviving population of short and long fragmented cycles. The results of this study demonstrate that a second complete sterilization cycle is unnecessary to assure the absence of living matter in the sterilized units.

  5. [Assessment of decontamination processes: cleaning, disinfection and sterilization in dental practice in Poland in the years 2011-2012].

    Science.gov (United States)

    Röhm-Rodowald, Ewa; Jakimiak, Bozenna; Chojecka, Agnieszka; Zmuda-Baranowska, Magdalena; Kanclerski, Krzysztof

    2012-01-01

    Effective decontamination of instruments is a key element of infection control and the provision of high quality in dental care. The aim of the study was to evaluate the efficiency of decontamination procedures including cleaning, disinfection and sterilization of re-usable instruments in dental practices in Poland. The efficiency of disinfection and sterilization processes have been evaluated on the results of the questionnaires. The following information were taken into account: setting where disinfection and sterilization had been performed, preparation of dental equipment for sterilization (disinfection, washing and cleaning, packaging), the types of autoclaves and used types of sterilization cycles, routine monitoring and documentation of sterilization processes, treatment of handpieces and the frequency of surface decontamination. Data were collected from 43 dental practices (35 dental offices and 8 clinics). Disinfection and cleaning processes were performed manually in 63% of dental offices and ultrasonic baths were used in 53% of settings. Washer disinfectors were used in 23% of dental practices: in every researched clinic and in a few dental offices. All sterilization processes were performed in steam autoclaves, mainly in small steam sterilizers (81%). Dental handpieces were sterilized in 72% of practices, but only 33% of them performed sterilization in recommended cycle B. Sterilization processes were monitored with chemical indicators in 33% of practices. Biological monitoring of the processes was carried out at different intervals. Incorrect documentation of instruments and surfaces decontamination was recorded in several settings. There is still a need for improvement of decontamination processes in dental practice in Poland. Areas for improvement include: replacement of manual cleaning and disinfection processes with automatic processes, sterilization of dental handpieces after each patient, monitoring of a sterilization process with chemical and

  6. Genetically conditioned male sterility

    International Nuclear Information System (INIS)

    Gottschalk, W.

    1976-01-01

    A survey is given of two different types of genetically controlled male sterility in higher plants. 'Functional' male sterility is due to the action of mutated genes causing a misdifferentiation of the growing points in different specific ways. Under the influence of the genes of this group either the stamens or the archespore tissues are not differentiated. In other mutants functionable male germ cells are produced but cannot be used for fertilizing the egg cells because the anthers remain closed or anthers and stigma become spatially separated from each other. Other genes of the group are responsible for the transformation of stamens into carpels, i.e. for a change of the hermaphrodite flower into a unisexually female one. A second type of male sterility is due to the action of ms genes influencing the course of micro-sporogenesis directly. They cause the breakdown of this process in a specific meiotic stage characteristic for each gene of the group. This breakdown is introduced by the degeneration of PMCs, microspores, or pollen grains preventing the production of male germ cells. The female sex organs remain uninfluenced. (author)

  7. Carbon partitioning as validation methods for crop yields and CO2 sequestration monitoring in Asia using a photosynthetic-sterility model

    Science.gov (United States)

    Kaneko, Daijiro; Yang, Peng; Kumakura, Toshiro

    2010-10-01

    Sustainability of world crop production and food security has become uncertain. The authors have developed an environmental research system called Remote Sensing Environmental Monitor (RSEM) for treating carbon sequestration by vegetation, grain production, desertification of Eurasian grassland, and CDM afforestation/ reforestation to a background of climate change and economic growth in rising Asian nations. The RSEM system involves vegetation photosynthesis and crop yield models for grains, including land-use classification, stomatal evaluation by surface energy fluxes, and daily monitoring for early warning. This paper presents a validation method for RSEM based on carbon partitioning in plants, focusing in particular on the effects of area sizes used in crop production statistics on carbon fixation and on sterility-based corrections to accumulated carbon sequestration values simulated using the RSEM photosynthesis model. The carbonhydrate in grains has the same chemical formula as cellulose in grain plants. The method proposed by partitioning the fixed carbon in harvested grains was used to investigate estimates of the amounts of carbon fixed, using the satellite-based RSEM model.

  8. Safety Picks up "STEAM"

    Science.gov (United States)

    Roy, Ken

    2016-01-01

    This column shares safety information for the classroom. STEAM subjects--science, technology, engineering, art, and mathematics--are essential for fostering students' 21st-century skills. STEAM promotes critical-thinking skills, including analysis, assessment, categorization, classification, interpretation, justification, and prediction, and are…

  9. STEAM by Design

    Science.gov (United States)

    Keane, Linda; Keane, Mark

    2016-01-01

    We live in a designed world. STEAM by Design presents a transdisciplinary approach to learning that challenges young minds with the task of making a better world. Learning today, like life, is dynamic, connected and engaging. STEAM (Science, Technology, Environment, Engineering, Art, and Math) teaching and learning integrates information in…

  10. Steampunk: Full Steam Ahead

    Science.gov (United States)

    Campbell, Heather M.

    2010-01-01

    Steam-powered machines, anachronistic technology, clockwork automatons, gas-filled airships, tentacled monsters, fob watches, and top hats--these are all elements of steampunk. Steampunk is both speculative fiction that imagines technology evolved from steam-powered cogs and gears--instead of from electricity and computers--and a movement that…

  11. Revisiting cosmological bounds on sterile neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, Aaron C. [Institute for Particle Physics Phenomenology (IPPP), Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Martínez, Enrique Fernández [Departamento and Instituto de Física Teórica (IFT), UAM/CSIC, Universidad Autonoma de Madrid, C/ Nicolás Cabrera 13-15, E-28049 Cantoblanco, Madrid (Spain); Hernández, Pilar; Mena, Olga [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de València, Apartado de Correos 22085, E-46071 Valencia (Spain); Lattanzi, Massimiliano, E-mail: aaron.vincent@durham.ac.uk, E-mail: enrique.fernandez-martinez@uam.es, E-mail: m.pilar.hernandez@uv.es, E-mail: omena@ific.uv.es, E-mail: lattanzi@fe.infn.it [Dipartimento di Fisica e Science della Terra, Università di Ferrara and INFN, sezione di Ferrara, Polo Scientifico e Tecnologico, Edificio C Via Saragat, 1, I-44122 Ferrara (Italy)

    2015-04-01

    We employ state-of-the art cosmological observables including supernova surveys and BAO information to provide constraints on the mass and mixing angle of a non-resonantly produced sterile neutrino species, showing that cosmology can effectively rule out sterile neutrinos which decay between BBN and the present day. The decoupling of an additional heavy neutrino species can modify the time dependence of the Universe's expansion between BBN and recombination and, in extreme cases, lead to an additional matter-dominated period; while this could naively lead to a younger Universe with a larger Hubble parameter, it could later be compensated by the extra radiation expected in the form of neutrinos from sterile decay. However, recombination-era observables including the Cosmic Microwave Background (CMB), the shift parameter R{sub CMB} and the sound horizon r{sub s} from Baryon Acoustic Oscillations (BAO) severely constrain this scenario. We self-consistently include the full time-evolution of the coupled sterile neutrino and standard model sectors in an MCMC, showing that if decay occurs after BBN, the sterile neutrino is essentially bounded by the constraint sin{sup 2}θ ∼< 0.026 (m{sub s}/eV){sup −2}.

  12. Steam generator life management

    International Nuclear Information System (INIS)

    Tapping, R.L.; Nickerson, J.; Spekkens, P.; Maruska, C.

    1998-01-01

    Steam generators are a critical component of a nuclear power reactor, and can contribute significantly to station unavailability, as has been amply demonstrated in Pressurized Water Reactors (PWRs). CANDU steam generators are not immune to steam generator degradation, and the variety of CANDU steam generator designs and tube materials has led to some unexpected challenges. However, aggressive remedial actions, and careful proactive maintenance activities, have led to a decrease in steam generator-related station unavailability of Canadian CANDUs. AECL and the CANDU utilities have defined programs that will enable existing or new steam generators to operate effectively for 40 years. Research and development work covers corrosion and mechanical degradation of tube bundles and internals, chemistry, thermal hydraulics, fouling, inspection and cleaning, as well as provision for specially tool development for specific problem solving. A major driving force is development of CANDU-specific fitness-for-service guidelines, including appropriate inspection and monitoring technology to measure steam generator condition. Longer-range work focuses on development of intelligent on-line monitoring for the feedwater system and steam generator. New designs have reduced risk of corrosion and fouling, are more easily inspected and cleaned, and are less susceptible to mechanical damage. The Canadian CANDU utilities have developed programs for remedial actions to combat degradation of performance (Gentilly-2, Point Lepreau, Bruce A/B, Pickering A/B), and have developed strategic plans to ensure that good future operation is ensured. This report shows how recent advances in cleaning technology are integrated into a life management strategy, discusses downcomer flow measurement as a means of monitoring steam generator condition, and describes recent advances in hideout return as a life management tool. The research and development program, as well as operating experience, has identified

  13. Gene, protein and network of male sterility in rice

    Directory of Open Access Journals (Sweden)

    Wang eKun

    2013-04-01

    Full Text Available Rice is one of the most important model crop plants whose heterosis has been well exploited in commercial hybrid seed production via a variety of types of male sterile lines. Hybrid rice cultivation area is steadily expanding around the world, especially in Southern Asia. Characterization of genes and proteins related to male sterility aims to understand how and why the male sterility occurs, and which proteins are the key players for microspores abortion. Recently, a series of genes and proteins related to cytoplasmic male sterility, photoperiod sensitive male sterility, self-incompatibility and other types of microspores deterioration have been characterized through genetics or proteomics. Especially the latter, offers us a powerful and high throughput approach to discern the novel proteins involving in male-sterile pathways which may help us to breed artificial male-sterile system. This represents an alternative tool to meet the critical challenge of further development of hybrid rice. In this paper, we reviewed the recent developments in our understanding of male sterility in rice hybrid production across gene, protein and integrated network levels, and also, present a perspective on the engineering of male sterile lines for hybrid rice production.

  14. Some approaches to numerical modelling of a phenomenon observed during steam generator tube rupture in the reactor with liquid metal coolant

    Directory of Open Access Journals (Sweden)

    Usov Eduard V.

    2017-01-01

    Full Text Available The presented paper contains a description of approaches to simulate processes, observed during leakage in the steam generator of the reactor with liquid metal coolant. These approaches have been implemented in thermal hydraulic code HYDRA-IBRAE/LM. To calculate motion of gas bubbles in liquid metal flow and heat transfer of gas bubbles with metal, different relations are used in HYDRA-IBRAE/LM code. The code contains models of chemical interaction between water and sodium for modelling of tube rupture in sodium cooled fast reactors, Modelling of the experiments has been made using HYDRA-IBRAE/LM code. The results of the modelling with determined main factors are presented in the article.

  15. A contribution to the modelling of steam reformers for natural gas fuelled fuel cell heating systems; Ein Beitrag zur Modellierung von Dampfreformern fuer erdgasbetriebene Brennstoffzellenheizgeraete

    Energy Technology Data Exchange (ETDEWEB)

    Nietzsche, Joerg

    2010-10-29

    The author attempted to verify the assumptions and simplifications of common mathematical models of small-scale steam reformers. The emphasis was on the derivation of important model parameters on the basis of easily identifiable catalyst, fluid and reactor characteristics. An easily validated 2D model of a reformer tube is then used for a wide sensitivity analysis and a comparative investigation of various reactor types. [German] Die Motivation dieser Arbeit liegt in der Ueberpruefung der bislang in mathematischen Modellen von kleintechnischen Dampfreformern getroffenen Annahmen und Vereinfachungen, mit speziellem Augenmerk auf die Aufklaerung der Herkunft wichtiger Modellparameter anhand von leicht bestimmbaren Katalysator-, Fluid- und Reaktoreigenschaften. Ein leicht zu validierendes, zweidimensionales Modell eines Reformerrohres soll im Anschluss fuer eine breit angelegte Sensitivitaetsanalyse und eine vergleichende Untersuchung verschiedener Reaktortypen dienen.

  16. Simulation of main steam and feedwater system of full scope simulator for Qinshan 300 MW Nuclear Power Unit

    International Nuclear Information System (INIS)

    Zhao Xiaoyu

    1996-01-01

    The simulation of main steam and feedwater system is the most important and maximal part in secondary circuit model, including all of main steam and feedwater's thermal-hydraulic properties, except heat-exchange of secondary side of steam generator. It simulates main steam header, steam power in each stage of turbine, moisture separator-reheater, deaerator, condenser, high pressure and low pressure heater, auxiliary feedwater and main steam bypass in full scope

  17. Deletion of mammalian sterile 20-like kinase 1 attenuates neuronal loss and improves locomotor function in a mouse model of spinal cord trauma.

    Science.gov (United States)

    Wang, Pan-Feng; Xu, Da-Yuan; Zhang, Yuntong; Liu, Xiao-Bin; Xia, Yan; Zhou, Pan-Yu; Fu, Qing-Ge; Xu, Shuo-Gui

    2017-07-01

    Neuronal cell death following spinal cord injury (SCI) is an important contributor to neurological deficits. The purpose of our work was to delineate the function of mammalian sterile 20-like kinase 1 (Mst1), a pro-apoptotic kinase and key mediator of apoptotic signaling, in the pathogenesis of an experimental mouse model of SCI. Male mice received a mid-thoracic spinal contusion injury, and it was found that phosphorylation of Mst1 at the injured site was enhanced significantly following SCI. Furthermore, when compared to the wild-type controls, Mst1-deficient mice displayed improved locomotor function by increased Basso mouse scale score. Deletion of Mst1 in mice attenuated loss of motor neurons and suppressed microglial and glial activation following SCI. Deletion of Mst1 in mice reduced apoptosis via suppressing cytochrome c release and caspase-3 activation following SCI. Deletion of Mst1 attenuated mitochondrial dysfunction and increased ATP formation following SCI. Deletion of Mst1 in mice inhibited local inflammation following SCI, evidenced by reduced activities of myeloperoxidase and protein levels of TNF-α, IL-1β, and IL-6. In conclusion, the present study demonstrated that deletion of Mst1 attenuated neuronal loss and improved locomotor function in a mouse model of SCI, via preserving mitochondrial function, attenuating mitochondria-mediated apoptotic pathway, and suppressing inflammation, at least in part.

  18. [Cost management: the implementation of the activity-based costing method in sterile processing department].

    Science.gov (United States)

    Jericó, Marli de Carvalho; Castilho, Valéria

    2010-09-01

    This exploratory case study was performed aiming at implementing the Activity-based Costing (ABC) method in a sterile processing department (SPD) of a major teaching hospital. Data collection was performed throughout 2006. Documentary research techniques and non participant closed observation were used. The ABC implementation allowed for learning the activity-based costing of both the chemical and physical disinfection cycle/load: (dollar 9.95) and (dollar 12.63), respectively; as well as the cost for sterilization by steam under pressure (autoclave) (dollar 31.37) and low temperature steam and gaseous formaldehyde sterilization (LTSF) (dollar 255.28). The information provided by the ABC method has optimized the overall understanding of the cost driver process and provided the foundation for assessing performance and improvement in the SPD processes.

  19. Thermal fatigue damage evaluation of a PWR NPP steam generator injection nozzle model subjected to thermal stratification phenomenon

    International Nuclear Information System (INIS)

    Leite da Silva, Luiz; Rodrigues Mansur, Tanius; Cimini Junior, Carlos Alberto

    2011-01-01

    Thermal stratification phenomenon with the same thermodynamic steam generator (SG) injection nozzle parameters was simulated. After 41 experiments, the experimental section was dismantled; cut and specimens were made of its material. Other specimens were made of the preserved pipe material. By comparing their fatigue tests results, the pipe material damage was evaluated. The water temperature layers and also the outside pipe wall temperatures were measured at the same level. Strains outside the pipe in 7 positions were measured. The experimental section develops thermal stratified flows, stresses and strains caused enlargement of material grain size and reduction in fatigue life.

  20. Minimize corrosion degradation of steam generator tube materials

    International Nuclear Information System (INIS)

    Lu, Y.

    2006-01-01

    As part of a coordinated program, AECL is developing a set of tools to aid with the prediction and management of steam generator performance. Although stress corrosion cracking (of Alloy 800) has not been detected in any operating steam generator, for life management it is necessary to develop mechanistic models to predict the conditions under which stress corrosion cracking is plausible. Experimental data suggest that all steam generator tube materials are susceptible to corrosion degradation under some specific off-specification conditions. The tolerance to the chemistry upset for each steam generator tube alloy is different. Electrochemical corrosion behaviors of major steam generator tube alloys were studied under the plausible aggressive crevice chemistry conditions. The potential hazardous conditions leading to steam generator tube degradation and the conditions, which can minimize steam generator tube degradation have been determined. Recommended electrochemical corrosion potential/pH zones were defined for all major steam generator tube materials, including Alloys 600, 800, 690 and 400, under CANDU steam generator operating and startup conditions. Stress corrosion cracking tests and accelerated corrosion tests were carried out to verify and revise the recommended electrochemical corrosion potential/pH zones. Based on this information, utilities can prevent steam generator material degradation surprises by appropriate steam generator water chemistry management and increase the reliability of nuclear power generating stations. (author)

  1. Ukraine Steam Partnership

    Energy Technology Data Exchange (ETDEWEB)

    Gurvinder Singh

    2000-02-15

    The Ukraine Steam Partnership program is designed to implement energy efficiency improvements in industrial steam systems. These improvements are to be made by the private plants and local government departments responsible for generation and delivery of energy to end-users. One of the activities planned under this program was to provide a two-day training workshop on industrial steam systems focusing on energy efficiency issues related to the generation, distribution, and consumption of steam. The workshop was geared towards plant managers, who are not only technically oriented, but are also key decision makers in their respective companies. The Agency for Rational Energy Use and Ecology (ARENA-ECO), a non-governmental, not-for-profit organization founded to promote energy efficiency and environmental protection in Ukraine, in conjunction with the Alliance staff in Kiev sent out invitations to potential participants in all the regions of Ukraine. The purpose of this report is the describe the proceedings from the workshop and provide recommendations from the workshop's roundtable discussion. The workshop was broken down into two main areas: (1) Energy efficient boiler house steam generation; and Energy efficient steam distribution and consumption. The workshop also covered the following topics: (1) Ukrainian boilers; (2) Water treatment systems; (3) A profile of UKRESCO (Ukrainian Energy Services Company); (4) Turbine expanders and electricity generation; (5) Enterprise energy audit basics; and (6) Experience of steam use in Donetsk oblast.

  2. Evaluation of different sterilization and disinfection methods on commercially made preformed crowns.

    Science.gov (United States)

    Yilmaz, Y; Guler, C

    2008-12-01

    The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM). Preformed crowns (NuSmile Primary Anterior Crown (NSC), Kinder Krowns (KK), Pedo Pearls (PP) and polycarbonate crowns (PC)) were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group); steam autoclaving at 134 degrees C (30 psi) for 4 min (G2); steam autoclaving at 134 degrees C (30 psi) for 12 min (G3); steam autoclaving at 121 degrees C (15 psi) for 30 min (G4); and ultrasonication in a bath containing 4% Lysetol AF for 5 min at room temperature (chemical disinfection) (G5). Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05) crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients.

  3. Steam generator tube failures

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  4. Steam generator tube failures

    International Nuclear Information System (INIS)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service

  5. Solar steam nanobubbles.

    Science.gov (United States)

    Polman, Albert

    2013-01-22

    Silica-gold core-shell nanoparticles that are immersed in water act as efficient nanoscale generators of steam when illuminated with sunlight. In their paper in this issue of ACS Nano, Halas, Nordlander, and co-workers demonstrate this intriguing phenomenon that results from the nucleation of steam at the surface of individual nanoparticles that are heated by the sun. The same effect is also used to demonstrate distillation of ethanol. The solar steam nanobubble generation phenomenon results from the complex interplay of many different phenomena that occur at the nanoscale, and can find a broad range of applications.

  6. In-flight cLFV conversion: {e-μ }, {e-τ } and {μ -τ } in minimal extensions of the standard model with sterile fermions

    Science.gov (United States)

    Abada, A.; De Romeri, V.; Orloff, J.; Teixeira, A. M.

    2017-05-01

    We revisit charged lepton flavour in-flight conversions, in which a beam of electrons or muons is directed onto a fixed target, e + N → μ +N, e + N → τ +N and μ + N → τ +N, focusing on elastic interactions with a nucleus N. After a general discussion of this observable, we carry a full phenomenological analysis in the framework of minimal Standard Model extensions via sterile neutrinos, with a strong emphasis on the rôle of the increasingly more stringent constraints arising from other (low-energy) charged lepton flavour-violation observables. Despite the potential interest of this observable, in particular in the light of certain upcoming facilities with the capability of very intense lepton beams, our study suggests that due to current bounds on three-body decays (ℓ _i → 3 ℓ _j) and μ -e conversion in nuclei, the expected number of conversions in such a minimal framework is dramatically reduced. An experimental observation of such a conversion would thus signal the presence of another source of flavour violation, possibly at tree level.

  7. Validation of radiation sterilization process

    International Nuclear Information System (INIS)

    Kaluska, I.

    2007-01-01

    The standards for quality management systems recognize that, for certain processes used in manufacturing, the effectiveness of the process cannot be fully verified by subsequent inspection and testing of the product. Sterilization is an example of such a process. For this reason, sterilization processes are validated for use, the performance of sterilization process is monitored routinely and the equipment is maintained according to ISO 13 485. Different aspects of this norm are presented

  8. Sterilization in the United States

    Science.gov (United States)

    Bartz, Deborah; Greenberg, James A

    2008-01-01

    Unintended pregnancies are expensive for patients and for society in terms of medical costs, the cost of caring for more children, and the cost to personal and professional goals. Sterilization is the most common contraceptive method utilized by couples in the United States. Given technological advances over the past few decades, male and female surgical sterilization has become a safe, convenient, easy, and highly effective birth control method for the long term. This article reviews current male and female sterilization options. PMID:18701927

  9. Sterilizing insects with ionizing radiation

    International Nuclear Information System (INIS)

    Bakri, A.; Mehta, K.; Lance, D.R.

    2005-01-01

    Exposure to ionizing radiation is currently the method of choice for rendering insects reproductively sterile for area-wide integrated pest management (AW-IPM) programmes that integrate the sterile insect technique (SIT). Gamma radiation from isotopic sources (cobalt-60 or caesium-137) is most often used, but high-energy electrons and X-rays are other practical options. Insect irradiation is safe and reliable when established safety and quality-assurance guidelines are followed. The key processing parameter is absorbed dose, which must be tightly controlled to ensure that treated insects are sufficiently sterile in their reproductive cells and yet able to compete for mates with wild insects. To that end, accurate dosimetry (measurement of absorbed dose) is critical. Irradiation data generated since the 1950s, covering over 300 arthropod species, indicate that the dose needed for sterilization of arthropods varies from less than 5 Gy for blaberid cockroaches to 300 Gy or more for some arctiid and pyralid moths. Factors such as oxygen level, and insect age and stage during irradiation, and many others, influence both the absorbed dose required for sterilization and the viability of irradiated insects. Consideration of these factors in the design of irradiation protocols can help to find a balance between the sterility and competitiveness of insects produced for programmes that release sterile insects. Many programmes apply 'precautionary' radiation doses to increase the security margin of sterilization, but this overdosing often lowers competitiveness to the point where the overall induced sterility in the wild population is reduced significantly. (author)

  10. Quality assurance of sterilized products: verification of a model relating frequency of contaminated items and increasing radiation dose

    International Nuclear Information System (INIS)

    Khan, A.A.; Tallentire, A.; Dwyer, J.

    1977-01-01

    Values of the γ-radiation resistance parameters (k and n of the 'multi-hit' expression) for Bacillus pumilus E601 spores and Serratia marcescens cells have been determined and the constancy of values for a given test condition demonstrated. These organisms, differing by a factor of about 50 in k value, have been included in a laboratory test system for use in verification of a model describing the dependence of the proportion of contaminated items in a population of items on radiation dose. The proportions of contaminated units of the test system at various γ-radiation doses have been measured for different initial numbers and types of organisms present in units either singly or together. Using the model, the probabilities of contaminated units for corresponding sets of conditions have been evaluated together with associated variances. Measured proportions and predicted probabilities agree well, showing that the model holds in a laboratory contrived situation. (author)

  11. Steam generator tube vibration study

    International Nuclear Information System (INIS)

    Enderlin, W.I.

    1986-01-01

    Chemical cleaning has been proposed to remove magnetite buildup in some pressurized water reactor steam generators. The US Nuclear Regulatory Commission (NRC) has expressed concern that such cleaning would combine with the tube denting caused by magnetite formation to enlarge tube/tube support plate clearances, increasing the level of flow-induced vibrations that could lead to unacceptably high tube wear and failure rates. In support of NRC, the Pacific Northwest Laboratory investigated whether such increased clearances would exacerbate tube fretting wear. Using a full-length scale model of a steam generator tube bundle, flow tests were conducted at an instrumented location through clearances representing as-built and post-cleaned tube conditions. Test results indicated little potential for increased tube wear as a result of chemical cleaning, under normal operating conditions at tube support locations similar to that tested

  12. Effect of the sterilization method on the properties of Bombyx mori silk fibroin films

    Energy Technology Data Exchange (ETDEWEB)

    George, Karina A. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059 (Australia); Shadforth, Audra M.A. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Chirila, Traian V., E-mail: traian.chirila@qei.org.au [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, 4072 (Australia); Faculty of Health Sciences, University of Queensland, Herston, Queensland 4006 (Australia); Faculty of Science and Engineering, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Laurent, Matthieu J. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Ecole Superieure d' Ingenieurs de Luminy (ESIL), Universite de la Mediterranee Aix-Marseille II, Luminy case 925 13288, Marseille, Cedex 09 (France); Stephenson, Sally-Anne [Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Queensland 4059 (Australia); Faculty of Health, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Edwards, Grant A. [Australian Institute of Bioengineering and Nanotechnology, University of Queensland, St Lucia, 4072 (Australia); Madden, Peter W. [Queensland Eye Institute, 41 Annerley Road, South Brisbane, Queensland 4101 (Australia); Faculty of Health Sciences, University of Queensland, Herston, Queensland 4006 (Australia); and others

    2013-03-01

    We have compared the effects of different sterilization techniques on the properties of Bombyx mori silk fibroin thin films with the view to subsequent use for corneal tissue engineering. The transparency, tensile properties, corneal epithelial cell attachment and degradation of the films were used to evaluate the suitability of certain sterilization techniques including gamma-irradiation (in air or nitrogen), steam treatment and immersion in aqueous ethanol. The investigations showed that gamma-irradiation, performed either in air or in a nitrogen atmosphere, did not significantly alter the properties of films. The films sterilized by gamma-irradiation or by immersion in ethanol had a transparency greater than 98% and tensile properties comparable to human cornea and amniotic membrane, the materials of choice in the reconstruction of ocular surface. Although steam-sterilization produced stronger, stiffer films, they were less transparent, and cell attachment was affected by the variable topography of these films. It was concluded that gamma-irradiation should be considered to be the most suitable method for the sterilization of silk fibroin films, however, the treatment with ethanol is also an acceptable method. - Highlights: Black-Right-Pointing-Pointer The effects of four methods of sterilization on the properties of silk fibroin films were investigated. Black-Right-Pointing-Pointer Steam treatment leads to stiffer films but to lower transparency and variable surface topography. Black-Right-Pointing-Pointer Degradation of fibroin is enhanced in the films that were gamma-irradiated. Black-Right-Pointing-Pointer The effects on mechanical properties are explained through changes in both primary and secondary structure of fibroin. Black-Right-Pointing-Pointer Gamma-irradiation and immersion in aqueous ethanol are suggested as preferred methods of sterilization.

  13. Light Sterile Neutrinos from Large Extra Dimensions

    OpenAIRE

    Ma, Ernest; Rajasekaran, G.; Sarkar, Utpal

    2000-01-01

    An experimentally verifiable Higgs-triplet model of neutrino masses from large extra dimensions was recently proposed. We extend it to accomodate a light sterile neutrino which also mixes with the three active neutrinos. A previously proposed phenomenological model of four neutrinos (\\underline {the only viable such model now left}, in view of the latest atmospheric and solar neutrino-oscillation data) is specifically realized.

  14. Compact solar autoclave based on steam generation using broadband light-harvesting nanoparticles.

    Science.gov (United States)

    Neumann, Oara; Feronti, Curtis; Neumann, Albert D; Dong, Anjie; Schell, Kevin; Lu, Benjamin; Kim, Eric; Quinn, Mary; Thompson, Shea; Grady, Nathaniel; Nordlander, Peter; Oden, Maria; Halas, Naomi J

    2013-07-16

    The lack of readily available sterilization processes for medicine and dentistry practices in the developing world is a major risk factor for the propagation of disease. Modern medical facilities in the developed world often use autoclave systems to sterilize medical instruments and equipment and process waste that could contain harmful contagions. Here, we show the use of broadband light-absorbing nanoparticles as solar photothermal heaters, which generate high-temperature steam for a standalone, efficient solar autoclave useful for sanitation of instruments or materials in resource-limited, remote locations. Sterilization was verified using a standard Geobacillus stearothermophilus-based biological indicator.

  15. French steam generator

    International Nuclear Information System (INIS)

    Remond, A.

    1986-01-01

    After recalling the potential damage mode of tubes of steam generator, the author recalls the safety criteria used in France. The improvements and the process of damage prejudice and reparation for tubular bundle are presented [fr

  16. Steam cleaning device

    International Nuclear Information System (INIS)

    Karaki, Mikio; Muraoka, Shoichi.

    1985-01-01

    Purpose: To clean complicated and long objects to be cleaned having a structure like that of nuclear reactor fuel assembly. Constitution: Steams are blown from the bottom of a fuel assembly and soon condensated initially at the bottom of a vertical water tank due to water filled therein. Then, since water in the tank is warmed nearly to the saturation temperature, purified water is supplied from a injection device below to the injection device above the water tank on every device. In this way, since purified water is sprayed successively from below to above and steams are condensated in each of the places, the entire fuel assembly elongated in the vertical direction can be cleaned completely. Water in the reservoir goes upward like the steam flow and is drained together with the eliminated contaminations through an overflow pipe. After the cleaning has been completed, a main steam valve is closed and the drain valve is opened to drain water. (Kawakami, Y.)

  17. The effects of inbreeding and heat stress on male sterility in Drosophila melanogaster

    DEFF Research Database (Denmark)

    Pedersen, Louise Dybdahl; Pedersen, Asger Roer; Bijlsma, Kuke

    2011-01-01

    in benign and stressful environments using Drosophila melanogaster as a model organism. Male sterility was compared in 21 inbred lines and five non-inbred control lines at 25.0 and 29.0 °C. The effect of inbreeding on sterility was significant only at 29.0 °C. This stress-induced increase in sterility...

  18. Modeling Cyclic Fatigue Hysteresis Loops of 2D Woven Ceramic Matrix Composites at Elevated Temperatures in Steam

    Directory of Open Access Journals (Sweden)

    Longbiao Li

    2016-05-01

    Full Text Available In this paper, the cyclic fatigue hysteresis loops of 2D woven SiC/SiC ceramic matrix composites (CMCs at elevated temperatures in steam have been investigated. The interface slip between fibers and the matrix existing in matrix cracking modes 3 and 5, in which matrix cracking and interface debonding occurred in longitudinal yarns, is considered as the major reason for hysteresis loops of 2D woven CMCs. The hysteresis loops of 2D SiC/SiC composites corresponding to different peak stresses, test conditions, and loading frequencies have been predicted using the present analysis. The damage parameter, i.e., the proportion of matrix cracking mode 3 in the entire matrix cracking modes of the composite, and the hysteresis dissipated energy increase with increasing fatigue peak stress. With increasing cycle number, the interface shear stress in the longitudinal yarns decreases, leading to transition of interface slip types of matrix cracking modes 3 and 5.

  19. Model studies of bubble size distribution and sound propagation at microleaks in sodium-heated steam generators

    International Nuclear Information System (INIS)

    Uhlmann, G.

    1979-01-01

    The reaction zone of a small water leak in a sodium-heated steam generator (microleak) has been simulated by jet gassing or argon in water. The bubble diameter distribution in the bubble flow has been measured using a photoelectric method. The bubble size distribution obtained can be approached by an exponential distribution. For this case, phase velocity and sound damping have been calculated in the two-phase mixture. In the case of small ratios of sound frequency to the expected value of bubble resonance frequency, the frequency-independent sound velocity of the homogeneous mixture is obtained as a function of the gas volume fraction. In the case of very high frequencies, the sound velocity of the pure liquid is obtained for any gas volume fractions. In the whole range investigated damping is strongly dependent on the frequency. (author)

  20. Study on Near Distributed Dynamic Model of a Multifountain-and-multiconfluent Network System of Steam Main-pipeline and Parallel Coursing Units

    Science.gov (United States)

    Lei, Pan; Jiong, Shen

    2007-06-01

    According to the deficiency of the prior modeling methods on main-pipeline system, the paper advances a near distributed modeling way based on subsection, combination and delamination for parallel coursing units and main-pipeline system to fully show its distributed dynamics by an easy-simulated mode of expression. Firstly, a principle is established to plot out the main-pipeline into some short pipe-sections between each pair of fountain/confluent points. Secondly, a near distributed decoupling transfer function matrix model without steady error for each pipe-section is built by rationally approximate deduction and then joined with the dynamic models of the fountain/confluent at the two ends of the pipe-section to form the near distributed model of each subsection. Finally, a smooth arithmetic is adopted to joint all the conterminous subsections into a whole system model. The modeling method above decreases the dimension of matter space and integrates more influence factors on the system dynamic characteristics into the built model, such as pipe length, diameter and the thermodynamics of working fluid, so it more particularly reflects the distributed dynamic characteristics of a multifountain-and-multiconfluent network system of steam main-pipeline and parallel coursing units than before, and can act well as the simulated research object for advanced main-pipeline system control arithmetic and distributed control technology or even validates them. Some simulation experiments have been done and produced good results to prove the validity of the modeling method.

  1. Sterilization of Extracted Human Teeth.

    Science.gov (United States)

    Pantera, Eugene A., Jr.; Schuster, George S.

    1990-01-01

    At present, there is no specific recommendation for sterilization of extracted human teeth used in dental technique courses. The purpose of this study was to determine whether autoclaving would be effective in the sterilization of extracted teeth without compromising the characteristics that make their use in clinical simulations desirable. (MLW)

  2. Future development LMFBR-steam generators SNR2

    International Nuclear Information System (INIS)

    Essebaggers, J.; Pors, J.G.

    1975-01-01

    The development work for steam generators for large LMFBR plants by Neratoom will be reviewed consisting of: 1. Development engineering information. 2. Concept select studies followed by conceptual designs of selected models. 3. Development manufacturing techniques. 4. Detail design of a prototype unit. 5. Testing of sub-constructions for prototype steam generators. In this presentation item 1 and 2 above will be high lighted, identifying the development work for the SNR-2 steam generators on short term basis. (author)

  3. Conditional sterility in plants

    Science.gov (United States)

    Meagher, Richard B.; McKinney, Elizabeth; Kim, Tehryung

    2010-02-23

    The present disclosure provides methods, recombinant DNA molecules, recombinant host cells containing the DNA molecules, and transgenic plant cells, plant tissue and plants which contain and express at least one antisense or interference RNA specific for a thiamine biosynthetic coding sequence or a thiamine binding protein or a thiamine-degrading protein, wherein the RNA or thiamine binding protein is expressed under the regulatory control of a transcription regulatory sequence which directs expression in male and/or female reproductive tissue. These transgenic plants are conditionally sterile; i.e., they are fertile only in the presence of exogenous thiamine. Such plants are especially appropriate for use in the seed industry or in the environment, for example, for use in revegetation of contaminated soils or phytoremediation, especially when those transgenic plants also contain and express one or more chimeric genes which confer resistance to contaminants.

  4. The Sterile Insect Technique

    International Nuclear Information System (INIS)

    Kiragu, J.

    2006-01-01

    Insect pests have caused an increasing problem in agriculture and human health through crop losses and disease transmission to man and livestock. Intervention to ensure food security and human health has relied on Integrated Pest Management (IPM) strategies to keep the pests population below economic injury levels. IPM integrate a variety of methods, but there has been over-reliance on chemical control following the discovery of insecticidal properties of DDT. It is now realized that, maintaining pest populations at controlled levels is unsustainable and eradication options is now being considered. Although the Sterile Insect Technique(SIT) could be used for insect suppression, it is gaining favour in the elimination (eradication) of the target pest population through Areawide-based IPM (Author)

  5. Ethylene Oxide Gaseous Sterilization

    Science.gov (United States)

    Ernst, Robert R.; Shull, James J.

    1962-01-01

    The duration of the equilibration period between admission of water vapor and subsequent introduction of gaseous ethylene oxide to an evacuated sterilizer chamber was studied with respect to its effect on the inactivation of spores of Bacillus subtilis var. niger under simulated practical conditions. Introduction of a water-adsorbing cotton barrier between the spores and an incoming gas mixture of water vapor and ethylene oxide caused a marked increase in the observed thermochemical death time of the spore populations. This effect was negated by admission of water vapor one or more minutes prior to introduction of ethylene oxide gas. Increases in temperature and relative humidity of the system promoted passage of water vapor through the cotton barriers and diminished their effect. PMID:13890660

  6. Sterile Endophthalmitis after Intravitreal Injections

    Directory of Open Access Journals (Sweden)

    Joaquín Marticorena

    2012-01-01

    Full Text Available Sterile endophthalmitis appears as an infrequent complication of intravitreal injections and seems to develop mainly in the context of the off-label use of drugs that have not been conceived for intravitreous administration. The aetiology of sterile endophthalmitis, independently of the administered drug, remains uncertain and a multifactorial origin cannot be discarded. Sterile inflammation secondary both to intravitreal triamcinolone acetonide and to intravitreal bevacizumab share many characteristics such as the acute and painless vision loss present in the big majority of the cases. Dense vitreous opacity is a common factor, while anterior segment inflammation appears to be mild to moderate. In eyes with sterile endophthalmitis, visual acuity improves progressively as the intraocular inflammation reduces without any specific treatment. If by any chance the ophthalmologist is not convinced by the sterile origin of the inflammation, this complication must be treated as an acute endophthalmitis because of the devastating visual prognosis of this intraocular infection in the absence of therapy.

  7. Electrolytic silver ion cell sterilizes water supply

    Science.gov (United States)

    Albright, C. F.; Gillerman, J. B.

    1968-01-01

    Electrolytic water sterilizer controls microbial contamination in manned spacecraft. Individual sterilizer cells are self-contained and require no external power or control. The sterilizer generates silver ions which do not impart an unpleasant taste to water.

  8. Iran eases limits on sterilization.

    Science.gov (United States)

    Roudi, N

    1991-03-01

    The government of Iran announced in November 1990, in an abrupt reversal of previous policies, the legislation of sterilization and its provision free-of-charge upon request, as well as the distribution of other contraceptive gratis. At the time of the Islamic Revolution in 1979 the government adopted a pronatalist policy, family planning programs were interrupted, legal ages of marriage were lowered, and barriers against polygamy were loosened. Iran had a 3.5% growth rate in 1990 and a total fertility rate of 6.3 lifetime births/woman. After the end of the war between Iran and Iraq in 1988, the population explosion became an obstacle to reconstruction. In 1950, the population numbered 14.2 million; by 1970 it had doubled to 28.4 million. In 1990, the country had 54.6 million people. According to a 1990 UN assessment the population will soar to 100 million by 2020. Over 8 million live in Tehran where overcrowding, traffic congestion, air pollution, and high living costs are the norm. the 1989 National Birth Control Policy Summary adopted targets to reduce the average number of lifetime births per woman to 4 children and natural growth rate to 2.3% by 2011, and to provide family planning to 24% of reproductive-age women whereby 1 million conceptions would be prevented. Indirect measures to curb fertility include raising literacy promoting the education of girls, improving the status and health conditions of women, and reducing maternal and child mortality. A media campaign has started to encourage a small family model. The low legal, social, educational, and employment status of women poses obstacles to this plan, however, the revision of laws that conflict with these goals has been urged. In other Islamic countries such as Turkey, Tunisia, Indonesia, Pakistan, and Bangladesh, female sterilization is legal. Abortion in Iran remains banned except for saving the life of the mother.

  9. Thermoeconomic and environmental analyses of a low water consumption combined steam power plant and refrigeration chillers – Part 1: Energy and economic modelling and analysis

    International Nuclear Information System (INIS)

    Ifaei, Pouya; Rashidi, Jouan; Yoo, ChangKyoo

    2016-01-01

    Highlights: • Proposing two energy systems by combining refrigeration chillers and power plants. • Model-based comparison of the systems through energy and economic standpoints. • Reducing total annual costs of the base system up to 4.7% by process integration. • Decreasing the water loss in wet cooling towers by up to 18% in the proposed system. • Suggesting a water-fuel economic management strategy based on parametric analysis. - Abstract: Two novel configurations are proposed to replace the conventional Rankine cycle based steam power plants (SPP) with natural draft wet cooling towers (NDWCT) as cooling units. Closed feedwater heater unit of the base SPP-NDWCT system is eliminated in order to combine a vapor compression refrigeration (VCR) and an absorption heat pump (ABHP) with the base SPP-NDWCT system. Both VCR-SPP-NDWCT and ABHP-SPP-NDWCT systems are integrated to decrease the NDWCT load which could result in water losses decrease. In part one of the presented two-part paper, model-based energy and economic analyses are performed to compare systems performance and applicability. The temperature difference at pinch point and temperature difference between the hot and cold sides of the heat exchangers which were used for systems integration in VCR-SPP-NDWCT, and the absorber pressure and temperature in ABHP-SPP-NDWCT system are studied using parametric analysis procedure. A water-fuel management strategy is also introduced for the ABHP-SPP-NDWCT system according to the influence of the absorber pressure changes on system water and fuel consumption. In part 2, environmental and thermoeconomic analyses are performed to complete a comprehensive study on designing steam power plants. The results of part 1 showed that water losses and total annual costs decreased by 1–18% and 0–4.7% for the ABHP-SPP-NDWCT system but increased by 11% and 60% for the VCR-SPP-NDWCT system, respectively.

  10. Reactor modeling to simulate catalytic partial oxidation and steam reforming of methane. Comparison of temperature profiles and strategies for hot spot minimization

    Energy Technology Data Exchange (ETDEWEB)

    Barrio, V.L.; Cambra, J.F.; Arias, P.L.; Gueemez, M.B. [School of Engineering (UPV/EHU), c/Alameda Urquijo s/n, 48013 Bilbao (Spain); Schaub, G.; Rohde, M. [Engler-Bunte-Institut, Universitaet Karlsruhe, Engler-Bunte-Ring 1, 76131 Karlsruhe (Germany); Rabe, S.; Vogel, F. [Paul Scherrer Institute, Laboratory for Energy and Materials Cycles, CH-5232 Villigen PSI (Switzerland)

    2007-07-15

    Catalytic partial oxidation (CPO) reactions of methane in the presence of steam (low temperature CPO, LTCPO) over a noble metal catalyst were investigated. A quasi-homogeneous one-dimensional model was developed in order to model a lab-scale fixed-bed reactor to produce syngas. These model calculations can contribute to the optimization of the process with respect to the formation of important hot spots ({delta} T{>=}130 ). These useful data can enable the model development in order to study the influence of the space velocity, product composition and other variables. Furthermore, a feed splitting study was performed. In the heat balance an overall heat transport term was included to account for small heat losses/gains along the reactor. The agreement between simulations and the degree of detail in the model is appropriate for the amount and kind of experimental data available. Thus, this model can also assist in a pilot reactor design, materials and further scale-up. (author)

  11. Steam-injected gas turbine analysis: steam rates

    Science.gov (United States)

    Rice, I. G.

    1995-04-01

    This paper presents an analysis of steam rates in steam-injected gas turbines (simple and reheat). In considering a gas turbine of this type, the steam-injection flow is separated from the main gas stream for analysis. Dalton's and Avogadro's laws of partial pressure and gas mixtures are applied. Results obtained provide for the accurate determination of heat input, gas expansion based on partial pressures, and heat-rejection steam-enthalpy points.

  12. Validation of Effective Models for Simulation of Thermal Stratification and Mixing Induced by Steam Injection into a Large Pool of Water

    Directory of Open Access Journals (Sweden)

    Hua Li

    2014-01-01

    Full Text Available The Effective Heat Source (EHS and Effective Momentum Source (EMS models have been proposed to predict the development of thermal stratification and mixing during a steam injection into a large pool of water. These effective models are implemented in GOTHIC software and validated against the POOLEX STB-20 and STB-21 tests and the PPOOLEX MIX-01 test. First, the EHS model is validated against STB-20 test which shows the development of thermal stratification. Different numerical schemes and grid resolutions have been tested. A 48×114 grid with second order scheme is sufficient to capture the vertical temperature distribution in the pool. Next, the EHS and EMS models are validated against STB-21 test. Effective momentum is estimated based on the water level oscillations in the blowdown pipe. An effective momentum selected within the experimental measurement uncertainty can reproduce the mixing details. Finally, the EHS-EMS models are validated against MIX-01 test which has improved space and time resolution of temperature measurements inside the blowdown pipe. Excellent agreement in averaged pool temperature and water level in the pool between the experiment and simulation has been achieved. The development of thermal stratification in the pool is also well captured in the simulation as well as the thermal behavior of the pool during the mixing phase.

  13. Influence of feedwater and blowdown systems on the mineral distribution in WWER steam generators

    International Nuclear Information System (INIS)

    Pappx, L.

    1994-01-01

    After modification of Dukovany NPP steam generator feedwater system, the increased concentration of minerals was measured in the cold leg of modified steam generator. Some modifications were performed on operating WWER 1000 steam generators with aim to optimize the water chemistry in the collectors area. Since the distribution of minerals can substantially affect on corrosion processes in steam generators, VITKOVICE, as a producer of WWER steam generators, has focused this attention on the optimizing of these systems. To predict the mineral distribution on the secondary side of steam generators for considered feedwater/blowdown systems, the simple model of flow distribution in the secondary side of SG was developed. (Author)

  14. Optimization of perforated distribution plate in steam generator PGV-1000MKO using CFD

    International Nuclear Information System (INIS)

    Volkov, V.Yu.; Golibrodo, L.A.; Krutikov, A.A.; Kudryavtsev, O.V.; Lakhov, D.A.; Nadinskij, Yu.N.; Nikolaeva, A.V.; Skibin, A.P.; Sotskov, V.V.

    2015-01-01

    Design of steam distribution perforated sheet SDPS for PGV-1000MKO was optimized using CFD methods, and guidelines for choosing the design of SDPS perforation were provided. Computational studies for optimized design of SDPS were performed for several characteristic variants of the mass water level in the steam generator and the distribution of the steam load. Recommendations for commissioning tests procedure for the SG were given on the basis of the research results. Processes in the PGV-1000MKO version with the collector equipped with ten steam nozzles were modeled. A comparison of technical parameters of the design with a single steam nozzle and with ten steam nozzles was performed [ru

  15. Optical wet steam monitor

    Science.gov (United States)

    Maxey, L.C.; Simpson, M.L.

    1995-01-17

    A wet steam monitor determines steam particle size by using laser doppler velocimeter (LDV) device to produce backscatter light. The backscatter light signal is processed with a spectrum analyzer to produce a visibility waveform in the frequency domain. The visibility waveform includes a primary peak and a plurality of sidebands. The bandwidth of at least the primary frequency peak is correlated to particle size by either visually comparing the bandwidth to those of known particle sizes, or by digitizing the waveform and comparing the waveforms electronically. 4 figures.

  16. Steam generator sludge removal apparatus

    International Nuclear Information System (INIS)

    Schafer, B.W.; Werner, C.E.; Klahn, F.C.

    1992-01-01

    The present invention relates to equipment for cleaning steam generators and in particular to a high pressure fluid lance for cleaning sludge off the steam generator tubes away from an open tube lane. 6 figs

  17. Food irradiation and sterilization

    International Nuclear Information System (INIS)

    Josephson, E.S.

    1981-01-01

    Radiation sterilization of food (radappertization) requires exposing food in sealed containers to ionizing radiation at absorbed doses high enough (25 to 70 kGy) to kill all organisms of food spoilage and public health significance. Radappertization is analogous to thermal canning in achieving shelf stability (long term storage without refrigeration). Except for dry products in which autolysis is negligible, the radappertization process also requires that the food be heated to an internal temperature of 70 to 80 0 C (bacon to 53 0 C) to inactivate autolytic enzymes which catalyze spoilage during storage without refrigeration. To minimize the occurrence of irradiation induced off-flavors and odors, undesirable color changes, and textural and nutritional losses from exposure to the high doses required for radappertization, the foods are vacuum sealed and irradiated frozen (-40 0 C to -20 0 C). Radappertized foods have the characteristic of fresh foods prepared for eating. Radappertization can substitute in whole or in part for some chemical food additives such as ethylene oxide and nitrites which are either toxic, carcinogenic, mutagenic, or teratogenic. After 27 years of testing for 'wholesomeness' (safety for consumption) of radappertized foods, no confirmed evidence has been obtained of any adverse effects of radappertization on the 'wholesomeness' characteristics of these foods. (author)

  18. Food irradiation and sterilization

    Science.gov (United States)

    Josephson, Edward S.

    Radiation sterilization of food (radappertization) requires exposing food in sealed containers to ionizing radiation at absorbed doses high enough (25-70 kGy) to kill all organisms of food spoilage and public health significance. Radappertization is analogous to thermal canning is achieving shelf stability (long term storage without refrigeration). Except for dry products in which autolysis is negligible, the radappertization process also requires that the food be heated to an internal temperature of 70-80°C (bacon to 53°C) to inactivate autolytic enzymes which catalyze spoilage during storage without refrigeration. To minimize the occurence of irradiation induced off-flavors and odors, undesirable color changes, and textural and nutritional losses from exposure to the high doses required for radappertization, the foods are vacuum sealed and irradiated frozen (-40°C to -20°C). Radappertozed foods have the characteristic of fresh foods prepared for eating. Radappertization can substitute in whole or in part for some chemical food additives such as ethylene oxide and nitrites which are either toxic, carcinogenic, mutagenic, or teratogenic. After 27 years of testing for "wholesomeness" (safety for consumption) of radappertized foods, no confirmed evidence has been obtained of any adverse effecys of radappertization on the "wholesomeness" characteristics of these foods.

  19. Hydrogen production from cheese whey by catalytic steam reforming: Preliminary study using lactose as a model compound

    International Nuclear Information System (INIS)

    Remón, J.; Laseca, M.; García, L.; Arauzo, J.

    2016-01-01

    Highlights: • Steam reforming of lactose: a promising strategy for cheese whey management. • Thermodynamic and experimental analyses of the effect of the operating conditions. • Reaction pathway showing the formation of the most important gas and liquid products. • Technical/energetic assessment: H 2 rich gas, C-free liquid and neutral energy process. - Abstract: Cheese whey is a yellowish liquid by-product of the cheese making process. Owing to its high BOD and COD values, this feedstock should not be directly discharged into the environment without appropriate treatment. Before dealing with real cheese whey, this work addresses the production of a rich hydrogen gas from lactose (the largest organic constituent of this waste) by catalytic steam reforming. This reforming process has been theoretically and experimentally studied. The theoretical study examines the effect of the temperature (300–600 °C), lactose concentration (1–10 wt.%) and N 2 (0–80 cm 3 STP/min) and liquid flow (0.1–0.5 mL/min) rates on the thermodynamic composition of the gas. The results show that the temperature and lactose concentration exerted the greatest influence on the thermodynamics. The experimental study, conducted in a fixed bed reactor using a Ni-based catalyst, considers the effect of the temperature (300–600 °C), lactose concentration (1–10 wt.%) and spatial time (4–16 g catalyst min/g lactose) on the global lactose conversion, product distribution on a carbon basis (gas, liquid and solid) and the compositions of the gas and liquid phases. Complete lactose conversion was achieved under all the experimental conditions. The carbon converted into gas, liquid and solid was 2–97%, 0–66% and 0–94%, respectively. The gas phase was made up of a mixture of H 2 (0–70 vol.%), CO 2 (20–70 vol.%), CO (2–34 vol.%) and CH 4 (0–3 vol.%). The liquid phase consisted of a mixture of aldehydes, ketones, carboxylic acids, sugars, furans, alcohols and phenols

  20. Function analysis of steam isolation valves

    International Nuclear Information System (INIS)

    Persson, R.; Kilpi, K.; Noro, H.; Siikonen, T.; Sjoeberg, A.; Wallen, G.; Aakesson, H.

    1981-01-01

    Function analysis of system-medium-operated steam isolation valves has been the objective of the Swedish-Finnish IVLS project, the results of which are presented in this report. Theoretical models were to be verified against available experimental data, to some extent from the HDR blowdown experiments, which are part of a German reactor safety program. Finnish hydraulic measurements on a valve model (scale 1:2.15) have been performed to give complementary data. The analysis work has covered the thermal-hydraulic behaviour of steam isolation valves as well as phenomena related to structural mechanics. Work performed under contract with the Swedish Nuclear Power Inspectorate. (Author)

  1. Function analysis of steam isolation valves

    International Nuclear Information System (INIS)

    Persson, R.; Sjoeberg, A.; Aakesson, H.; Kilpi, K.; Noro, H.; Siikonen, T.; Wallen, G.

    1981-01-01

    Function analysis of system-medium-operated steam isolation valves has been the objective of the Swedish-Finnish IVLS project, the results of which are presented in this report. Theoretical models were to be verified against available experimental data, to some extent from the HDR blowdown experiments, which are part of a German reactor safety program. Finnish hydraulic measurements on a valve model (scale 1:2.15) have been performed to give complementary data. The analysis work has covered the thermal-hydraulic behaviour of steam isolation valves as well as phenomena related to structural mechanics. (Auth.)

  2. Steam microturbines in distributed cogeneration

    CERN Document Server

    Kicinski, Jan

    2014-01-01

    This book presents the most recent trends and concepts in power engineering, especially with regard to prosumer and civic energy generation. In so doing, it draws widely on his experience gained during the development of steam microturbines for use in small combined heat and power stations based on the organic Rankine cycle (CHP-ORC). Major issues concerning the dynamic properties of mechanical systems, in particular rotating systems, are discussed, and the results obtained when using unconventional bearing systems, presented. Modeling and analysis of radial-flow and axial-flow microturbines a

  3. Steam generators - problems and prognosis

    International Nuclear Information System (INIS)

    Tapping, R.L.

    1997-05-01

    Steam-generator problems, largely a consequence of corrosion and fouling, have resulted in increased inspection requirements and more regulatory attention to steam-generator integrity. In addition, utilities have had to develop steam-generator life-management strategies, including cleaning and replacement, to achieve design life. This paper summarizes the pertinent data to 1993/1994, and presents an overview of current steam-generator management practices. (author)

  4. Documentation requirements for radiation sterilization

    DEFF Research Database (Denmark)

    Miller, A.

    1995-01-01

    Several standards are recently approved or are under development by the standard organizations ISO and CEN in the field of radiation sterilization. Particularly in Europe these standards define new requirements on some issues and on other issues they emphasize the necessary documentation for appr......Several standards are recently approved or are under development by the standard organizations ISO and CEN in the field of radiation sterilization. Particularly in Europe these standards define new requirements on some issues and on other issues they emphasize the necessary documentation...... for approval of radiation sterilized products. The impact of these standards on the radiation sterilization is discussed, with special attention given to a few special issues, mainly traceability and uncertainty of measurement results....

  5. Sterile pyuria: a forgotten entity

    OpenAIRE

    Goonewardene, Sanchia; Persad, Raj

    2015-01-01

    Sterile pyuria is a common entity. Yet there are no guidelines to address this issue. We have conducted a systematic review over 20 years and reviewed the results. Guidelines for assessment, diagnosis and management are developed based on these results.

  6. Sterile pyuria: a forgotten entity.

    Science.gov (United States)

    Goonewardene, Sanchia; Persad, Raj

    2015-10-01

    Sterile pyuria is a common entity. Yet there are no guidelines to address this issue. We have conducted a systematic review over 20 years and reviewed the results. Guidelines for assessment, diagnosis and management are developed based on these results.

  7. Teachers' Perceptions and Practices of STEAM Education in South Korea

    Science.gov (United States)

    Park, HyunJu; Byun, Soo-yong; Sim, Jaeho; Han, Hyesook; Baek, Yoon Su

    2016-01-01

    This study examined teachers' perceptions and practices of science, technology, engineering, arts, and mathematics (STEAM) education in South Korea, drawing on a survey of teachers in STEAM model schools. Results showed that the majority of Korean teachers, especially experienced teachers and male teachers, had a positive view on the role of STEAM…

  8. Maximal oil recovery by simultaneous condensation of alkane and steam

    NARCIS (Netherlands)

    Bruining, J.; Marchesin, D.

    2007-01-01

    This paper deals with the application of steam to enhance the recovery from petroleum reservoirs. We formulate a mathematical and numerical model that simulates coinjection of volatile oil with steam into a porous rock in a one-dimensional setting. We utilize the mathematical theory of conservation

  9. Sterility assurance of medical products

    International Nuclear Information System (INIS)

    Dierksheide, W.C.

    1977-01-01

    The present methods of regulating medical devices under the Food, Drug and Cosmetic Act in the United States of America are outlined. Reference is made to the position of drugs sterilized by irradiation. Surgical sutures and surgical dressings are regulated as drugs. Some details are given of proposed changes in the Act. The subject is further discussed under the headings: sterility assurance, and biocompatibility. (U.K.)

  10. Food packaging and radiation sterilization

    International Nuclear Information System (INIS)

    Kawamura, Yoko

    1998-01-01

    Radiation sterilization has several merits that it is a positively effective sterilization method, it can be used to sterilize low heat-resistant containers and high gas barrier films, and there is no possibility of residual chemicals being left in the packages. It has been commercially used in 'Bag in a Box' and some food containers. The γ ray and an electron beam are commonly used in radiation sterilization. The γ ray can sterilize large size containers and containers with complex shapes or sealed containers due to its strong transmission capability. However, since the equipment tends to be large and expensive, it is generally used in off production lines. On the other hand, it is possible to install and electron beam system on food production lines since the food can be processed in a short time due to its high beam coefficient and its ease of maintenance, even though an electron beam has limited usage such as sterilizing relatively thin materials and surface sterilization due to the weak transmission. A typical sterilization dose is approximately 10-30 kGy. Direct effects impacting packaging materials, particularly plastics, include scission of polymer links, cross-linkage between polymers, and generating radiolysis products such as hydrogen, methane, aliphatic hydrocarbons, etc. Furthermore, under the existence of oxygen, the oxygen radicals generated by the radiation will oxidize and peroxidize polymer chains and will generate alcohol and carbonyl groups, which shear polymer links, and generate oxygen containing low molecular compounds. As a result, degradation of physical strength such as elongation and seal strength, generating foreign odor, and an increase in global migration values shown in an elution test are sometimes evident. The food packages have different shapes, materials, additives, number of microorganisms and purpose. Therefor the effects of radiation, the optimum dose and so on must be investigated on the individual package. (J.P.N.)

  11. An Industrial Steam Distillation

    Science.gov (United States)

    Potter, Frederick S.; Schuerch, Conrad

    1975-01-01

    Describes an undergraduate chemistry experiment which demonstrates the use of codistillation for the separation of substances of low volatility from nonvolatiles. Pine gum is separated into turpentine and rosin by means of codistillation with steam at temperatures above 100 degrees centigrade. (MLH)

  12. Radiation sterilization of skin allograft

    Science.gov (United States)

    Kairiyama, E.; Horak, C.; Spinosa, M.; Pachado, J.; Schwint, O.

    2009-07-01

    In the treatment of burns or accidental loss of skin, cadaveric skin allografts provide an alternative to temporarily cover a wounded area. The skin bank facility is indispensable for burn care. The first human skin bank was established in Argentina in 1989; later, 3 more banks were established. A careful donor selection is carried out according to the national regulation in order to prevent transmissible diseases. As cadaveric human skin is naturally highly contaminated, a final sterilization is necessary to reach a sterility assurance level (SAL) of 10 -6. The sterilization dose for 106 batches of processed human skin was determined on the basis of the Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control (2004) and ISO 11137-2 (2006). They ranged from 17.6 to 33.4 kGy for bioburdens of >10-162.700 CFU/100 cm 2. The presence of Gram negative bacteria was checked for each produced batch. From the analysis of the experimental results, it was observed that the bioburden range was very wide and consequently the estimated sterilization doses too. If this is the case, the determination of a tissue-specific dose per production batch is necessary to achieve a specified requirement of SAL. Otherwise if the dose of 25 kGy is preselected, a standardized method for substantiation of this dose should be done to confirm the radiation sterilization process.

  13. Radiation sterilization of skin allograft

    International Nuclear Information System (INIS)

    Kairiyama, E.; Horak, C.; Spinosa, M.; Pachado, J.; Schwint, O.

    2009-01-01

    In the treatment of burns or accidental loss of skin, cadaveric skin allografts provide an alternative to temporarily cover a wounded area. The skin bank facility is indispensable for burn care. The first human skin bank was established in Argentina in 1989; later, 3 more banks were established. A careful donor selection is carried out according to the national regulation in order to prevent transmissible diseases. As cadaveric human skin is naturally highly contaminated, a final sterilization is necessary to reach a sterility assurance level (SAL) of 10 -6 . The sterilization dose for 106 batches of processed human skin was determined on the basis of the Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control (2004) and ISO 11137-2 (2006). They ranged from 17.6 to 33.4 kGy for bioburdens of >10-162.700 CFU/100 cm 2 . The presence of Gram negative bacteria was checked for each produced batch. From the analysis of the experimental results, it was observed that the bioburden range was very wide and consequently the estimated sterilization doses too. If this is the case, the determination of a tissue-specific dose per production batch is necessary to achieve a specified requirement of SAL. Otherwise if the dose of 25 kGy is preselected, a standardized method for substantiation of this dose should be done to confirm the radiation sterilization process.

  14. Radiation sterilization of buckwheat flour

    International Nuclear Information System (INIS)

    Ito, Hitoshi; Ishigaki, Isao; Muramatsu, Nobuyuki; Oohinata, Hiroshi; Ohara, Tadahiko; Oh-ike, Terui; Matsuhashi, Tetsujiro.

    1989-01-01

    For buckwheat noodle in which taste is important and its main material, buckwheat flour, the ordinary sterilization by heating or ozone cannot be applied. The number of the bacteria sticking to buckwheat flour is much more as compared with that of wheat flour, and is 10 5 -10 7 per 1 g. The effective countermeasures are not yet found. Also noxious insects are apt to infect buckwheat flour. It has been known that radiation is effective for the sterilization of flavorings. In this study, the microorganism contamination of buckwheat flour and sterilization dose, the change of taste and properties after irradiation, and the capability of storage were examined, and the results are reported. The bacteria in buckwheat flour were mostly Erwinia which forms yellow colonies, and is plant-parasitic bacteria having sugar fermentation function, and also some Enterobacer, Klebsiella and Aspergillus were found. When gamma ray was irradiated on buckwheat flour, it was sterilized to less than 10 3 per 1 g bacteria at the dose of 5 kGy, and microorganisms were almost sterilized at 10 kGy. With the electron beam of 3 MeV, the effect of sterilization somewhat decreased. The noodle-making property of irradiated buckwheat flour, and the taste and storage capability of the noodle of irradiated flour were tested. (K.I.)

  15. Sterile Neutrino Search in the NOvA Far Detector

    Energy Technology Data Exchange (ETDEWEB)

    Edayath, Sijith [Cochin U.; Aurisano, Adam [Cincinnati U.; Sousa, Alexandre [Cincinnati U.; Davies, Gavin [Indiana U.; Suter, Louise [Fermilab; Yang, Shaokai [Cincinnati U.

    2017-10-03

    The majority of neutrino oscillation experiments have obtained evidence for neutrino oscillations that are compatible with the three-flavor model. Explaining anomalous results from short-baseline experiments, such as LSND and MiniBooNE, in terms of neutrino oscillations requires the existence of sterile neutrinos. The search for sterile neutrino mixing conducted in NOvA uses a long baseline of 810 km between Near Detector (ND) at Fermilab and Far Detector (FD) in Minnesota. The signal for sterile neutrino oscillations is a deficit of neutral-current neutrino interactions at the FD with respect to the ND prediction. In this document, We will present the analysis improvements that we are implementing for future NC sterile neutrino searches with NOvA. These include: improved modelling of our detector response; the inclusion of NC 2p2h interaction modelling; implementing a better energy reconstruction techniques; and including possible oscillation due to sterile neutrinos in the ND . This improvements enable us to do a simultaneous ND-FD shape fit of the NC energy spectrum covering a wider sterile mass range than previous analyses.

  16. Steam line break analysis in CAREM-25 reactor

    International Nuclear Information System (INIS)

    Zanocco, Pablo; Gimenez, Marcelo O.; Vertullo, Alicia; Schlamp, Miguel A.; Garcia, Alicia E.

    2000-01-01

    The main objective of this report is to analyze the reactor response during a steam line break postulated accident with RELAP5, a plant code using a separated flow model. The steam line break caused a rapid blowdown of the secondary coolant increasing the heat removal in the steam generator. As a consequence and due to reactor features the core power is also increased. As maximum removed power in the secondary side is highly dependant on the total water volume evaporated during the accident a detailed model of feed water and outlet steam pipes is provided. Different cases are analyzed with and without feedwater system and considering the fail or success of the First Shutdown System. In all the sequences the DNBR and CPR remain above the minimum safety values established by design. Further calculations concerning depressurization ramps and steam generator feed water pumps response during depressurization are advised. (author)

  17. Stability study in one step steam generators

    International Nuclear Information System (INIS)

    Abbate, P.

    1990-01-01

    The TWO program is presented developed for the behaviour limit calculation stable in one step steam generators for the case of Density Waves phenomenom. The program is based on a nodal model which, using Laplace transformation equations, allows to study the system's transfer functions and foresee the beginning of the unstable behaviour. This program has been satisfactorily validated against channels data uniformly heated in the range from 4.0 to 6.0 Mpa. Results on the CAREM reactor's steam generator analysis are presented. (Author) [es

  18. Fourth international seminar on horizontal steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Tuomisto, H. [ed.] [IVO Group, Vantaa (Finland); Purhonen, H. [ed.] [VTT, Espoo (Finland); Kouhia, V. [ed.] [Lappeenranta Univ. of Technology (Finland)

    1997-12-31

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries.

  19. Fourth international seminar on horizontal steam generators

    International Nuclear Information System (INIS)

    Tuomisto, H.; Purhonen, H.; Kouhia, V.

    1997-01-01

    The general objective of the International Seminars of Horizontal Steam Generator Modelling has been the improvement in understanding of realistic thermal hydraulic behaviour of the generators when performing safety analyses for VVER reactors. The main topics presented in the fourth seminar were: thermal hydraulic experiments and analyses, primary collector integrity, feedwater distributor replacement, management of primary-to-secondary leakage accidents and new developments in the VVER safety technology. The number of participants, representing designers and manufacturers of the horizontal steam generators, plant operators, engineering companies, research organizations, universities and regulatory authorities, was 70 from 10 countries

  20. Bridging the Gap: From Model Surfaces to Nanoparticle Analogs for Selective Oxidation and Steam Reforming of Methanol and Selective Hydrogenation Catalysis

    Science.gov (United States)

    Boucher, Matthew B.

    Most industrial catalysts are very complex, comprising of non-uniform materials with varying structures, impurities, and interaction between the active metal and supporting substrate. A large portion of the ongoing research in heterogeneous catalysis focuses on understanding structure-function relationships in catalytic materials. In parallel, there is a large area of surface science research focused on studying model catalytic systems for which structural parameters can be tuned and measured with high precision. It is commonly argued, however, that these systems are oversimplified, and that observations made in model systems do not translate to robust catalysts operating in practical environments; this discontinuity is often referred to as a "gap." The focus of this thesis is to explore the mutual benefits of surface science and catalysis, or "bridge the gap," by studying two catalytic systems in both ultra-high vacuum (UHV) and near ambient-environments. The first reaction is the catalytic steam reforming of methanol (SRM) to hydrogen and carbon dioxide. The SRM reaction is a promising route for on-demand hydrogen production. For this catalytic system, the central hypothesis in this thesis is that a balance between redox capability and weak binding of reaction intermediates is necessary for high SRM activity and selectivity to carbon dioxide. As such, a new catalyst for the SRM reaction is developed which incorporates very small amounts of gold (liquid-phase, stirred-tank batch reactor under a hydrogen head pressure of approximately 7 bar. Palladium alloyed into the surface of otherwise inactive copper nanoparticles shows a marked improvement in selectivity when compared to monometallic palladium catalysts with the same metal loading. This effect is attributed hydrogen spillover onto the copper surface. In summary, the development of new, highly active and selective catalysts for the methanol steam reforming reaction and for the partial hydrogenation of alkynes

  1. The applicability of CFD to simulate and study the mixing process and the thermo-hydraulic consequences of a main steam line break in PWR model

    Directory of Open Access Journals (Sweden)

    Farkas Istvan

    2017-01-01

    Full Text Available This paper focuses on the validation and applicability of CFD to simulate and analyze the thermo-hydraulic consequences of a main steam line break. Extensive validation data come from experiments performed using the Rossendorf coolant mixing model facility. For the calculation, the range of 9 to 12 million hexahe¬dral cells was constructed to capture all details in the interrogation domain in the system. The analysis was performed by running a time-dependent calculation, Detailed analyses were made at different cross-sections in the system to evaluate not only the value of the maximum and minimum temperature, but also the loca¬tion and the time at which it occurs during the transient which is considered to be indicator for the quality of mixing in the system. CFD and experimental results were qualitatively compared; mixing in the cold legs with emergency core cooling systems was overestimated. This could be explained by the sensitivity to the bound¬ary conditions. In the downcomer, the experiments displayed higher mixing: by our assumption this related to the dense measurement grid (they were not modelled. The temperature distribution in the core inlet plane agreed with the measurement results. Minor deviations were seen in the quantitative comparisons: the maximum temperature difference was 2ºC.

  2. Program for parameter studies of steam generators

    International Nuclear Information System (INIS)

    Mathisen, R.P.

    1982-11-01

    R2-GEN is a computer code for stationary thermal parameter studies of steam generators. The geometry and data are valid for Ringhals-2 generators. Subroutines and relevant calculations are included. The program is based on a heterogeneous flow model and some applications on tubes with varying contamination are presented. (G.B.)

  3. Sterilization in Finland: from eugenics to contraception.

    Science.gov (United States)

    Hemminki, E; Rasimus, A; Forssas, E

    1997-12-01

    The purpose of this paper was to describe the transition of sterilization in Finland from an eugenic tool to a contraceptive. Historical data were drawn from earlier reports in Finnish. Numbers of and reasons for sterilizations since 1950 were collected from nationwide sterilization statistics. Prevalence, characteristics of sterilized women, and women's satisfaction with sterilizations were studied from a 1994 nationwide survey (74% response rate). Logistic regression was used for adjustments. In the first half of the 20th century, eugenic ideology had influence in Finland as in other parts of Europe, and the 1935 and 1950 sterilization laws had an eugenic spirit. Regardless of this, the numbers of eugenic sterilizations remained low, and in practice, family planning was the main reason for sterilization. Nonetheless, prior to 1970 not all sterilizations were freely chosen, because sterilizations were sometimes used as a precondition for abortion. Female sterilizations showed remarkable fluctuation over time. Male sterilizations have been rare. The reasons stipulated by the law did not explain the numbers of sterilizations. In a 1994 survey, 9% of Finnish women reported they were using sterilization as their current contraceptive method (n = 189). Compared to women using other contraceptive methods, sterilized women were older, had had more births and pregnancies, and came from lower social classes. Sterilized women were satisfied with their sterilization, but there were women (8.5%) who regretted it. In conclusion, sterilizations have been and are likely to continue to be an important family planning method in Finland. The extreme gender ratio suggests a need for promoting male sterilizations, and women's expressed regrets suggest consideration of a higher age limit.

  4. Radiation: A means of sterilization

    International Nuclear Information System (INIS)

    Mukherjee, R.N.

    1975-01-01

    The sterilization of medical products by ionizing radiation is a well-established industrial process in a number of technologically advanced countries. It is indeed encouraging to note the rate of growth experienced during the past fifteen years. Starting with the first commercial plant in the early sixties in the USA there are to date more than sixty large facilities of this kind located in USA, Canada, Australia and the countries of Europe including USSR. The geographical distribution of these sterilization plants is rather unbalanced. In this respect Europe is far ahead of the other continents of the world, with about 65% of all sterilization plants, followed by North and South America with 17%, Asia with 8%, Australia and New Zealand with 9% and Africa with only 1%. During the last 10 years the IAEA has actively contributed to the development of radiation sterilization practices and technology in the Member States, with particular emphasis on the developing countries. Such promotional efforts have been made by (a) supporting co-ordinated research to accumulate relevant technical information, (b) organizing scientific meetings and training courses, (c) providing technical expertise in the form of fellowships and expert services, (d) providing technical assistance to conduct market surveys and economic feasibility assessment, (e) scientific publications, including technical manuals and proceedings reports, and (f) assistance in the formulation of an international 'Code of Practice' for standardization of the manufacturing practices for radiation sterilized medical products to meet the specified requirements of the various national Pharmacopoeias and of the international consumer market

  5. Sterilization of mentally retarded persons.

    Science.gov (United States)

    Van der Merwe, J V; Roux, J P

    1987-08-01

    South Africa's Abortion and Sterilization Act No 2 (1975) authorizes sterilization for severely retarded women provided the procedure is performed in a state hospital, certified by 2 medical practitioners (1 a psychiatrist), and the parent or guardian gives informed consent. Since 1975, 152 sterilizations (140 female, 12 male) have been performed under the provisions of this Act at Pretoria's H F Verwoerd Hospital. 92% of the patients were under 20 years of age. The majority were classified as profoundly or severely retarded (74) or moderately severely retarded (68). There were 20 patients with Down's syndrome and 22 with cerebral palsy. Hysterectomy was the method of choice in the 109 women in whom menstrual hygiene was a pertinent factor; the remaining 31 women were sterilized by tubal ligation. 98% of the parents or guardians of hysterectomy acceptors surveyed were satisfied with their decision and its outcome. Several indicated their daughter was more calm, cooperative, productive, and less irritable once relieved of her menstrual periods. A multidisciplinary team approach to the decision making process and the individualization of each case are essential to protect the rights of the mentally retarded. Factors such as the psychological trauma likely to result from pregnancy and childbirth, an inability to use contraception, and unsuitability to rear a child must be demonstrated. To ensure that legislation pertaining to the sterilization of the mentally retarded does not lead to abuse, inputs from the mental health professions are required.

  6. Effect of Different Sterilization Methods on the Extracted Oil from Oil Palm Fruit

    International Nuclear Information System (INIS)

    Hasimah Kasmin; Hasimah Kasmin; Roila Awang; Azwan Mat Lazim

    2015-01-01

    Sterilization is important process during the processing of oil palm fruits in order to produce crude palm oil (CPO). This process can be carried out using steam (conventional method), dry heating or wet heating method. In this study, the effectiveness of the dry heating and wet heating method for sterilization and solvent extraction were carried out. The sterilization time of these two methods were varied at 30, 60 and 90 min in order to determine their effectiveness on the oil extraction and their quality. Results showed that, at 30 min of sterilization, the wet heating produced a higher percentage of oil extraction compared to the conventional and dry heating, with average of 27.65 %, 19.01 % and 20.21 % respectively. In comparison with the conventional method, both sterilization methods gave better FFA and DOBI results. This can be seen where the average of free fatty acid (FFA) content for proposed sterilization method was between 0.37 % to 0.93 % while, average deterioration of bleach ability index (DOBI) was from 4.89 to 6.12. The average carotene content was in agreement with the conventional method at a range of 644.64 ppm to 764.80 ppm. (author)

  7. Active acoustic leak detection for LMFBR steam generator. Pt. 5. Experiment for detection of bubbles using the SG full sector model

    International Nuclear Information System (INIS)

    Kumagai, Hiromichi

    1997-01-01

    In order to prevent the expansion of tube damages and to maintain structural safety in steam generators (SG) of fast breeder reactors (FBR), it is necessary to detect precisely and immediately the leakage of water from tubes of heat exchangers. Therefore, an active acoustic method, which detects the sound attenuation due to bubbles generated in the sodium-water reactions, it being developed. In this paper, the attenuation characteristics of sound attenuated by bubbles and influence of background noise are investigated experimentally by using an SG full sector model (diameter ratio about 1/1, height ratio about 1/7) simulating the actual SG. As an experimental result, the received sound attenuation for ten seconds was more than 10 dB from air bubble injection when injected bubble of 10 l/s (equivalence water leak rate about 10 g/s). The attenuation of sound are least affected by bubble injection position of heat exchanger tube bunch department. And the time was about 25 seconds till the sound attenuation became 10 dB in case of quantity of air bubble 1 l/s (equivalent water leak rate about 1 g/s). It is clarified that the background noise hardly influenced water leak detection performance as a result of having examined influence of background noise. (author)

  8. A model of the operator cognitive behaviors during the steam generator tube rupture accident at a nuclear power plant

    International Nuclear Information System (INIS)

    Mun, J. H.; Kang, C. S.

    1996-01-01

    An integrated framework of modeling the human operator cognitive behavior during nuclear power plant accident scenarios is presented. It incorporates both plant and operator models. The basic structure of the operator model is similar to that of existing cognitive models, however, this model differs from those existing ones largely in two aspects. First, using frame and membership function, the pattern matching behavior, which is identified as the dominant cognitive process of operators responding to an accident sequence, is explicitly implemented in this model. Second, the non-task-related human cognitive activities like effects of stress and cognitive biases such as confirmation bias and availability bias, are also considered. A computer code, OPEC is assembled to simulate this framework and is actually applied to an SGTR sequence, and the resultant simulated behaviors of operator are obtained. 28 refs., 4 figs., 6 tabs. (author)

  9. Steam generator management program

    International Nuclear Information System (INIS)

    Cho, Nam Cheoul; Kim, Moo Soo; Lee, Kwang Woo

    2003-01-01

    Recently, the common concern of nuclear power industry in the development of technology mitigating and preventing the aging of steam generator tubes prevails, because the trends of steam generator flaws at Uljin unit no. 1,2 and KSNP impose a burden on the operation of nuclear power plant. While the regulatory agency is demanding the establishment of the advanced general performance maintenance system, the steam generator management program adapting advanced technology is being developed which may comply with EPRI PWR SG guidelines based on NEI 97-06. General guidelines including all the maintenance aspects consist of the tube integrity assessment criteria, repair limit, allowable leakage level, water chemistry will be composed in order to obtain the approval of regulatory agency and be applied to nuclear power plant early 2005. This presentation is to introduce maintenance state including SG tube degradation and main contents of advanced SG management program being developed, and furthermore update present and future plan, and estimate the alternation after the completion

  10. What is geothermal steam worth?

    International Nuclear Information System (INIS)

    Thorhallsson, S.; Ragnarsson, A.

    1992-01-01

    Geothermal steam is obtained from high-temperature boreholes, either directly from the reservoir or by flashing. The value of geothermal steam is similar to that of steam produced in boilers and lies in its ability to do work in heat engines such as turbines and to supply heat for a wide range of uses. In isolated cases the steam can be used as a source of chemicals, for example the production of carbon dioxide. Once the saturated steam has been separated from the water, it can be transported without further treatment to the end user. There are several constraints on its use set by the temperature of the reservoir and the chemical composition of the reservoir fluid. These constraints are described (temperature of steam, scaling in water phase, gas content of steam, well output) as are the methods that have been adopted to utilize this source of energy successfully. Steam can only be transported over relatively short distances (a few km) and thus has to be used close to the source. Examples are given of the pressure drop and sizing of steam mains for pipelines. The path of the steam from the reservoir to the end user is traced and typical cost figures given for each part of the system. The production cost of geothermal steam is estimated and its sensitivity to site-specific conditions discussed. Optimum energy recovery and efficiency is important as is optimizing costs. The paper will treat the steam supply system as a whole, from the reservoir to the end user, and give examples of how the site-specific conditions and system design have an influence on what geothermal steam is worth from the technical and economic points of view

  11. Mushrooms as Efficient Solar Steam-Generation Devices.

    Science.gov (United States)

    Xu, Ning; Hu, Xiaozhen; Xu, Weichao; Li, Xiuqiang; Zhou, Lin; Zhu, Shining; Zhu, Jia

    2017-07-01

    Solar steam generation is emerging as a promising technology, for its potential in harvesting solar energy for various applications such as desalination and sterilization. Recent studies have reported a variety of artificial structures that are designed and fabricated to improve energy conversion efficiencies by enhancing solar absorption, heat localization, water supply, and vapor transportation. Mushrooms, as a kind of living organism, are surprisingly found to be efficient solar steam-generation devices for the first time. Natural and carbonized mushrooms can achieve ≈62% and ≈78% conversion efficiencies under 1 sun illumination, respectively. It is found that this capability of high solar steam generation is attributed to the unique natural structure of mushroom, umbrella-shaped black pileus, porous context, and fibrous stipe with a small cross section. These features not only provide efficient light absorption, water supply, and vapor escape, but also suppress three components of heat losses at the same time. These findings not only reveal the hidden talent of mushrooms as low-cost materials for solar steam generation, but also provide inspiration for the future development of high-performance solar thermal conversion devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Hiding an elephant: heavy sterile neutrino with large mixing angle does not contradict cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Bezrukov, F. [The University of Manchester, School of Physics and Astronomy, Oxford Road, Manchester M13 9PL (United Kingdom); Chudaykin, A.; Gorbunov, D., E-mail: Fedor.Bezrukov@manchester.ac.uk, E-mail: chudy@ms2.inr.ac.ru, E-mail: gorby@ms2.inr.ac.ru [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation)

    2017-06-01

    We study a model of a keV-scale sterile neutrino with a relatively large mixing with the Standard Model sector. Usual considerations predict active generation of such particles in the early Universe, which leads to constraints from the total Dark Matter density and absence of X-ray signal from sterile neutrino decay. These bounds together may deem any attempt of creation of the keV scale sterile neutrino in the laboratory unfeasible. We argue that for models with a hidden sector coupled to the sterile neutrino these bounds can be evaded, opening new perspectives for the direct studies at neutrino experiments such as Troitsk ν-mass and KATRIN. We estimate the generation of sterile neutrinos in scenarios with the hidden sector dynamics keeping the sterile neutrinos either massless or superheavy in the early Universe. In both cases the generation by oscillations from active neutrinos in plasma is suppressed.

  13. Optimal design of vertical natural circulation steam generator weight

    International Nuclear Information System (INIS)

    Qin Huimin; Yan Changqi; Wang Jianjun; Wang Meng; He Shijing

    2011-01-01

    The steam generator is one of the key equipment in the PWR nuclear power plant, which has relative large weight and dimension, nowadays, it tends to using high capacity steam generators, which makes the steam generators to be heavier and larger, and it causes difficulties to the transport and arrangement of steam generators. Therefore, it is necessary to apply optimization techniques to the design of the steam generator in order to achieve the minimum weight or Janume by means of finding the optimum combination of design parameters while satisfying the heat exchange requirements and safety constraints. In this work, the evaluation model and corresponding codes of a vertical natural circulation steam generator were established, and based on the sensitivity analysis of thermohydraulic parameters and structural parameters which influence steam generator weight, the optimal design of steam generator, taking the net weight as objective, was carried out using a complex-genetic algorithm. The optimal results indicate that the net weight of optimum design is 17.16%, less than original design. The result shows an obvious effect which proves the possibility of optimization and can provide reference for real engineering design. (authors)

  14. Wet steam wetness measurement in a 10 MW steam turbine

    Directory of Open Access Journals (Sweden)

    Kolovratník Michal

    2014-03-01

    Full Text Available The aim of this paper is to introduce a new design of the extinction probes developed for wet steam wetness measurement in steam turbines. This new generation of small sized extinction probes was developed at CTU in Prague. A data processing technique is presented together with yielded examples of the wetness distribution along the last blade of a 10MW steam turbine. The experimental measurement was done in cooperation with Doosan Škoda Power s.r.o.

  15. The mathematical model structural-parametric synthesis of working processes in an oxygen-methane steam generator with flow swirl

    Science.gov (United States)

    Timoshinova, T. S.; Shmatov, D. P.; Kretinin, A. V.; Drozdov, I. G.

    2017-11-01

    While formulating a mathematical model of the flow and interaction between oxygen-methane fuel combustion products with tangentially swirled ballast water injected in the end of the combustion chamber in CAE product Fluent, which integrated into the ANSYS Workbench platform, the problem of structural-parametric synthesis is solved for structure optimization of the model. Equations are selected from the catalogue of Fluent physical models. Also optimization helps to find “regime” model parameters that determine the specific implementation of the model inside the synthesized structure. As a result, such solutions which were developed during creation of a numerical algorithm, as the choice of a turbulence model and the state equation, the methods for determining the thermodynamic thermophysical characteristics of combustion products, the choice of the radiation model, the choice of the resistance law for drops, the choice of the expression which allows to evaluate swirling flows lateral force, determination of the turbulent dispersion strength, choice of the mass exchange law, etc. Fields of temperature, pressure, velocity and volume fraction of phases were obtained at different ballast water mass flows. Dependence of wall temperature from mass flow of ballast water is constructed, that allows us to compare results of the experiment and mathematical modeling.

  16. Steam Turbine Control Valve Stiction Effect on Power System Stability

    International Nuclear Information System (INIS)

    Halimi, B.

    2010-01-01

    One of the most important problems in power system dynamic stability is low frequency oscillations. This kind of oscillation has significant effects on the stability and security of the power system. In some previous papers, a fact was introduced that a steam pressure continuous fluctuation in turbine steam inlet pipeline may lead to a kind of low frequency oscillation of power systems. Generally, in a power generation plant, steam turbine system composes of some main components, i.e. a boiler or steam generator, stop valves, control valves and turbines that are connected by piping. In the conventional system, the turbine system is composed with a lot of stop and control valves. The steam is provided by a boiler or steam generator. In an abnormal case, the stop valve shuts of the steal flow to the turbine. The steam flow to the turbine is regulated by controlling the control valves. The control valves are provided to regulate the flow of steam to the turbine for starting, increasing or decreasing the power, and also maintaining speed control with the turbine governor system. Unfortunately, the control valve has inherent static friction (stiction) nonlinearity characteristics. Industrial surveys indicated that about 20-30% of all control loops oscillate due to valve problem caused by this nonlinear characteristic. In this paper, steam turbine control valve stiction effect on power system oscillation is presented. To analyze the stiction characteristic effect, firstly a model of control valve and its stiction characteristic are derived by using Newton's laws. A complete tandem steam prime mover, including a speed governing system, a four-stage steam turbine, and a shaft with up to for masses is adopted to analyze the performance of the steam turbine. The governor system consists of some important parts, i.e. a proportional controller, speed relay, control valve with its stiction characteristic, and stem lift position of control valve controller. The steam turbine has

  17. Gamma-Ray Sterilization of Mars Analog Rocks and Minerals

    Science.gov (United States)

    Allen, C. C.

    1998-01-01

    Samples of rock and soil, collected by robotic spacecraft on Mars, will be returned to terrestrial laboratories early in the next century. Plans call for the samples to be placed immediately in biological containment and tested for signs of present or past life and biological hazard. It is recommended that "controlled distribution of unsterilized materials from Mars should occur only if rigorous analyses determine that the materials do not constitute a biological hazard. If any portion of the sample is removed from containment prior to completion of these analyses it should first be sterilized." While sterilization of Mars samples may not be required, an acceptable method must be available before the samples are returned to Earth. Various techniques are routinely used to sterilize biological samples. These include dry heating to temperatures of 150C or higher, heating in the presence of steam, exposure to poisonous gases such as formaldehyde and propiolactone, exposure to H2O2 vapor or plasma, exposure to ultraviolet light, and exposure to gamma radiation. The appropriate technique depends on the physical characteristics of the sample and the desired results. Gamma radiation is routinely used to inactivate viruses and destroy bacteria in medical research. The most commercial sterilizers use Cobalt 60, which emits gamma photons with energies of 1. 173 and 1. 332 MeV. Absorbed doses of approximately 106 rad (104 gamma ray is equal to 104 ergs/gm) are sufficient to destroy most bacteria. The current study is designed to investigate the effects of lethal doses of Cobalt 60 gamma radiation on geologic materials analogous to the first samples to be returned from Mars. The goals are (1) to determine the gamma ray dose required to kill microorganisms within geologic samples, and (2) to determine the effects of lethal doses of gamma radiation on the physical and chemical properties of the samples.

  18. Radiation sterilization of hydrocortisone acetate

    International Nuclear Information System (INIS)

    Charef, A.; Boussaha, A.

    1989-09-01

    The feasibility of using high energy ionizing radiation for the sterilization of hydrocortisone acetate was investigated. Hydrocortisone acetate in the form of powder was exposed to different dose levels of gamma radiation using a Cobalt-60 source. The irradiated samples were examined by various physico-chemical techniques in order to detect possible radiolysis products. It was of interest to know if one could insure sterility and retain biological properties of the drug by suitable choice of radiation dose. The results showed that a 10 KGy radiation dose causes no change in the physico-chemical properties of the drug and is sufficient to obtain contaminant-free product

  19. Removal of NAPLs from the unsaturated zone using steam: prevention of downward migration by injecting mixtures of steam and air

    DEFF Research Database (Denmark)

    Schmidt, R.; Gudbjerg, Jacob; Sonnenborg, Torben Obel

    2002-01-01

    injection technology is presented, where a mixture of steam and air was injected. In twodimensional experiments with unsaturated porous medium contaminated with nonaqueous phase liquids, it was demonstrated how injection of pure steam lead to severe downward migration. Similar experiments, where steam......Steam injection for remediation of porous media contaminated by nonaqueous phase liquids has been shown to be a potentially efficient technology. There is, however, concern that the technique may lead to downward migration of separate phase contaminant. In this work, a modification of the steam...... and air were injected simultaneously, resulted in practically no downward migration and still rapid cleanup was achieved. The processes responsible for the prevention of downward migration when injecting steam–air mixtures were analyzed using a nonisothermal multiphase flow and transport model. Hereby...

  20. Steam generators, turbines, and condensers. Volume six

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Volume six covers steam generators (How steam is generated, steam generation in a PWR, vertical U-tube steam generators, once-through steam generators, how much steam do steam generators make?), turbines (basic turbine principles, impulse turbines, reaction turbines, turbine stages, turbine arrangements, turbine steam flow, steam admission to turbines, turbine seals and supports, turbine oil system, generators), and condensers (need for condensers, basic condenser principles, condenser arrangements, heat transfer in condensers, air removal from condensers, circulating water system, heat loss to the circulating water system, factors affecting condenser performance, condenser auxiliaries)

  1. Steam turbines for the future

    International Nuclear Information System (INIS)

    Trassl, W.

    1988-01-01

    Approximately 75% of the electrical energy produced in the world is generated in power plants with steam turbines (fossil and nuclear). Although gas turbines are increasingly applied in combined cycle power plants, not much will change in this matter in the future. As far as the steam parameters and the maximum unit output are concerned, a certain consolidation was noted during the past decades. The standard of development and mathematical penetration of the various steam turbine components is very high today and is applied in the entire field: For saturated steam turbines in nuclear power plants and for steam turbines without reheat, with reheat and with double reheat in fossil-fired power plants and for steam turbines with and without reheat in combined cycle power plants. (orig.) [de

  2. IGA/SCC propagation rate measurements on alloy 600 steam generator tubing using a side stream model boiler

    International Nuclear Information System (INIS)

    Takamatsu, H.; Matsueda, K.; Matsunaga, T.; Kitera, T.; Arioka, K.; Tsuruta, T.; Okamoto, S.

    1993-01-01

    IGA/SCC crack propagation rate measurements using various types of IGA/SCC predefected ALloy 600 tubing were tested in model boilers, a side stream model boiler at Ohi Unit 1 and similar model boilers in the laboratory. Types of IGA/SCC predefects introduced from the outside of the tubing were as follows. (1) Actual IGA/SCC predefect introduced by high temperature caustic environments; (2) Longitudinal predefect by electrodischarge machining (EDM) method, and then crack tip fatigue was introduced to serve as the marker on the fractured surface (EDM slit + fatigue). IGA/SCC crack propagation rate was measured after the destructive examination by Cr concentration profile on fracture surface for (1), and observation of intergranular fractured surface propagated from the marked fatigue was employed for (2) and (3) after the model boiler tests. As for the water chemistry conditions, mainly AVT (high N 2 H 4 ) + boric acid (5-10ppm as B in SGs) treatment for both model boilers, and some of the tests for the model boiler in the laboratory employed AVT (high N 2 H 4 ) without boric acid. The results of IGA/SCC crack propagation rate measurements were compared with each other, and the three methods employed showed a good coincidence with the rate of ca. 1 x 10 -5 mm/Hr for AVT (high N 2 H 4 ) + boric acid treatment condition, in the case that crack tip boron intensity (B/O value by IMMA analysis) of more than 1 was observed

  3. Dynamic and control of a once through steam generator

    International Nuclear Information System (INIS)

    Gomes, Arivaldo Vicente

    1979-01-01

    This paper presents a non linear distributed parameter model for the dynamics and feedback control of a large countercurrent heat exchanger used as a once through steam generator for a breeder reactor power plant. A convergent, implicit method has been developed to solve simultaneously the equations of conservation of mass, momentum and energy. The model, applicable to heat exchanger systems in general, has been used specifically to study the performance of a once-through steam generator with respect to its load following ability and stability of throttle steam temperature and pressure. (author)

  4. Potential unintended pregnancies averted and cost savings associated with a revised Medicaid sterilization policy.

    Science.gov (United States)

    Borrero, Sonya; Zite, Nikki; Potter, Joseph E; Trussell, James; Smith, Kenneth

    2013-12-01

    Medicaid sterilization policy, which includes a mandatory 30-day waiting period between consent and the sterilization procedure, poses significant logistical barriers for many women who desire publicly funded sterilization. Our goal was to estimate the number of unintended pregnancies and the associated costs resulting from unfulfilled sterilization requests due to Medicaid policy barriers. We constructed a cost-effectiveness model from the health care payer perspective to determine the incremental cost over a 1-year time horizon of the current Medicaid sterilization policy compared to a hypothetical, revised policy in which women who desire a postpartum sterilization would face significantly reduced barriers. Probability estimates for potential outcomes in the model were based on published sources; costs of Medicaid-funded sterilizations and Medicaid-covered births were based on data from the Medicaid Statistical Information System and The Guttmacher Institute, respectively. With the implementation of a revised Medicaid sterilization policy, we estimated that the number of fulfilled sterilization requests would increase by 45%, from 53.3% of all women having their sterilization requests fulfilled to 77.5%. Annually, this increase could potentially lead to over 29,000 unintended pregnancies averted and $215 million saved. A revised Medicaid sterilization policy could potentially honor women's reproductive decisions, reduce the number of unintended pregnancies and save a significant amount of public funds. Compared to the current federal Medicaid sterilization policy, a hypothetical, revised policy that reduces logistical barriers for women who desire publicly funded, postpartum sterilization could potentially avert over 29,000 unintended pregnancies annually and therefore lead to cost savings of $215 million each year. © 2013.

  5. Association of Hysteroscopic vs Laparoscopic Sterilization With Procedural, Gynecological, and Medical Outcomes.

    Science.gov (United States)

    Bouillon, Kim; Bertrand, Marion; Bader, Georges; Lucot, Jean-Philippe; Dray-Spira, Rosemary; Zureik, Mahmoud

    2018-01-23

    Safety of hysteroscopic sterilization has been recently questioned following reports of general symptoms such as allergy, tiredness, and depression in addition to associated gynecological results such as pelvic pain, perforation of fallopian tubes or uterus, and unwanted pregnancy. To compare the risk of reported adverse events between hysteroscopic and laparoscopic sterilization. French nationwide cohort study using the national hospital discharge database linked to the health insurance claims database. Women aged 30 to 54 years receiving a first hysteroscopic or laparoscopic sterilization between 2010 and 2014 were included and were followed up through December 2015. Hysteroscopic sterilization vs laparoscopic sterilization. Risks of procedural complications (surgical and medical) and of gynecological (sterilization failure that includes salpingectomy, second sterilization procedure, or pregnancy; pregnancy; reoperation) and medical outcomes (all types of allergy; autoimmune diseases; thyroid disorder; use of analgesics, antimigraines, antidepressants, benzodiazepines; outpatient visits; sickness absence; suicide attempts; death) that occurred within 1 and 3 years after sterilization were compared using inverse probability of treatment-weighted Cox models. Of the 105 357 women included (95.5% of eligible participants; mean age, 41.3 years [SD, 3.7 years]), 71 303 (67.7% ) underwent hysteroscopic sterilization, and 34 054 (32.3%) underwent laparoscopic sterilization. During the hospitalization for sterilization, risk of surgical complications for hysteroscopic sterilization was lower: 0.13% for hysteroscopic sterilization vs 0.78% for laparoscopic sterilization (adjusted risk difference [RD], -0.64; 95% CI, -0.67 to -0.60) and was lower for medical complications: 0.06% vs 0.11% (adjusted RD, -0.05; 95% CI, -0.08 to -0.01). During the first year after sterilization, 4.83% of women who underwent hysteroscopic sterilization had a higher risk of sterilization

  6. Sterile Neutrino Searches in MINOS and MINOS+ Experiments

    International Nuclear Information System (INIS)

    Huang, Junting

    2015-01-01

    This dissertation presents the searches on sterile neutrinos using the data collected in MINOS+ Experiment from September 2013 to September 2014, and the full data set of MINOS Experiment collected from 2005 to 2012. Anomalies in short baseline experiments, such as LSND and MiniBooNE, showed hints of sterile neutrinos, a type of neutrino that does not interact with the Standard Model particles. In this work, two models are considered: 3+1 and large extra dimension (LED). In the 3+1 model, one sterile neutrino state is added into the standard oscillation scheme consisting of three known active neutrino states v e , v μ and v τ . In the LED model, sterile neutrinos arise as Kaluza-Klein (KK) states due to assumed large extra dimensions. Mixing between sterile and active neutrino states may modify the oscillation patterns observed in the MINOS detectors. Both searches yield null results. For 3+1, a combined fit of MINOS and MINOS+ data gives a stronger limit on θ 24 in the range of 10 -2 eV 2 < Δm 43 2 < 1 eV 2 than previous experiments. For LED, with the complete MINOS data set, the size of extra dimensions is constrained to be smaller than ~ 0.35 μm at 90% C.L. in the limit of a vanishing lightest neutrino mass.

  7. Sterile Neutrino Searches in MINOS and MINOS+ Experiments

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Junting [Univ. of Texas, Austin, TX (United States)

    2015-05-01

    This dissertation presents the searches on sterile neutrinos using the data collected in MINOS+ Experiment from September 2013 to September 2014, and the full data set of MINOS Experiment collected from 2005 to 2012. Anomalies in short baseline experiments, such as LSND and MiniBooNE, showed hints of sterile neutrinos, a type of neutrino that does not interact with the Standard Model particles. In this work, two models are considered: 3+1 and large extra dimension (LED). In the 3+1 model, one sterile neutrino state is added into the standard oscillation scheme consisting of three known active neutrino states ve, vμ and vτ. In the LED model, sterile neutrinos arise as Kaluza-Klein (KK) states due to assumed large extra dimensions. Mixing between sterile and active neutrino states may modify the oscillation patterns observed in the MINOS detectors. Both searches yield null results. For 3+1, a combined fit of MINOS and MINOS+ data gives a stronger limit on θ24 in the range of 10-2 eV2 < Δm412 < 1 eV2 than previous experiments. For LED, with the complete MINOS data set, the size of extra dimensions is constrained to be smaller than ~ 0.35 μm at 90% C.L. in the limit of a vanishing lightest neutrino mass.

  8. Transgenic technologies to induce sterility

    Directory of Open Access Journals (Sweden)

    Wimmer Ernst A

    2009-11-01

    Full Text Available Abstract The last few years have witnessed a considerable expansion in the number of tools available to perform molecular and genetic studies on the genome of Anopheles mosquitoes, the vectors of human malaria. As a consequence, knowledge of aspects of the biology of mosquitoes, such as immunity, reproduction and behaviour, that are relevant to their ability to transmit disease is rapidly increasing, and could be translated into concrete benefits for malaria control strategies. Amongst the most important scientific advances, the development of transgenic technologies for Anopheles mosquitoes provides a crucial opportunity to improve current vector control measures or design novel ones. In particular, the use of genetic modification of the mosquito genome could provide for a more effective deployment of the sterile insect technique (SIT against vector populations in the field. Currently, SIT relies on the release of radiation sterilized males, which compete with wild males for mating with wild females. The induction of sterility in males through the genetic manipulation of the mosquito genome, already achieved in a number of other insect species, could eliminate the need for radiation and increase the efficiency of SIT-based strategies. This paper provides an overview of the mechanisms already in use for inducing sterility by transgenesis in Drosophila and other insects, and speculates on possible ways to apply similar approaches to Anopheles mosquitoes.

  9. Establishment of a sterilization dose

    International Nuclear Information System (INIS)

    Kaluska, I.

    2007-01-01

    Factors that impact on product bioburden (population of diable microorganisms on or in product and/or sterile barrier system) are: Raw materials, components, product design and size, manufacturing process, manufacturing equipment, manufacturing environment and manufacturing location. Presented lecture describes all these factors in details

  10. Sterilization In Protective Trade Policies

    OpenAIRE

    寺崎, 克志; Katsushi, Terasaki; 経営学部経営学科

    2007-01-01

    Under a government budget constraint export subsidies automatically sterilize distortions caused by import tariffs, i.e., without the cost of the trade policy implementation the policy mix of export subsidies and import tariffs with budget constraint makes the economy effective.

  11. On calculation of a steam-water flow in a geothermal well

    Science.gov (United States)

    Shulyupin, A. N.; Chermoshentseva, A. A.

    2013-08-01

    Approaches to calculation of a steam-water flow in a geothermal well are considered. For hydraulic applications, a WELL-4 model of a steam-water well is developed. Data obtained using this model are compared with experimental data and also with calculations by similar models including the well-known HOLA model. The capacity of the A-2 well in the Mutnovskoe flash-steam field (Kamchatka half-island, Russia) after planned reconstruction is predicted.

  12. Analysis of fast reactor steam generator performance

    International Nuclear Information System (INIS)

    Hulme, G.; Curzon, A.F.

    1992-01-01

    A computer model for the prediction of flow and temperature fields within a fast reactor steam generator unit is described. The model combines a commercially available computational fluid dynamics (CFD) solver (PHOENICS) with a steam-tube calculation and provides solutions for the fully coupled flow and temperature fields on both the shell side and the tube side. The model includes the inlet and outlet headers and the bottom end stagnant zone. It also accounts for the effects of support grids and edge-gaps. Two and three dimensional and transient calculations have been performed for both straight tube and J-tube units. Examples of the application of the model are presented. (7 figures) (Author)

  13. Physical model of lean suppression pressure oscillation phenomena: steam condensation in the light water reactor pressure suppression system (PSS)

    International Nuclear Information System (INIS)

    McCauley, E.W.; Holman, G.S.; Aust, E.; Schwan, H.; Vollbrandt, J.

    1980-01-01

    Using the results of large scale multivent tests conducted by GKSS, a physical model of chugging is developed. The unique combination of accurate digital data and cinematic data has provided the derivation of a detailed, quantified correlation between the dynamic physical variables and the associated two-phase thermo-hydraulic phenomena occurring during lean suppression (chugging) phases of the loss-of-coolant accident in a boiling water reactor pressure suppression system

  14. Development and evaluation of the NSSS model with four steam lines for the LVNP using the SCDAPSIM code

    International Nuclear Information System (INIS)

    Salazar C, J.H.; Nunez C, A.; Camargo C, R.

    2005-01-01

    The present work shows the pattern of the NSSS considering the four main vapor lines as well as their evaluation. The pattern was developed by the National Commission of Nuclear Security and Safeguards (CNSNS) and it has as main objective to account with a model of the Laguna Verde Nuclear power plant (CNLV) for the simulation and analysis of transitory events where are involved some of main vapor lines, or some relief valves and safety (SRV's). The model was evaluated with data of the CNLV. In 1996 the Federal Commission of Electricity (CFE) request to the CNSNS permission to operate the Unit 2 until the first recharge, having the main vapor line 'B' isolated and operating with a level of power corresponding to a flow of total vapor of 85% of the nominal one (of 1931 MWt). The obtained values were compared with the obtained registrations of the CNLV in order to evaluate the model. Those results show relative errors inferior to 3% among the CNLV reported value and the one calculated by the SCDAPSIM code. (Author)

  15. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1984-10-01

    A review of the performance of steam generator tubes in 116 water-cooled nuclear power reactors showed that tubes were plugged at 54 (46 percent) of the reactors. The number of tubes removed from service decreased from 4 692 (0.30 percent) in 1981 to 3 222 (0.20 percent) in 1982. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that have used only volatile treatment, with or without condensate demineralization

  16. Radiation sterilization: an industrial process

    International Nuclear Information System (INIS)

    Ley, F.J.

    1975-01-01

    A new dimension has been added to the use of radiation in the medical field with the introduction of radiation as a sterilizing agent. Its use in diagnosis through radioactive tracers or X-rays and in therapy administered with the most sophisticated of electrical machines or radioisotope units, is familiar in the hospital world, being well established therein. In contrast, the application of radiation sterilization is in industry where the installation of large radiation sources is already commonplace in many countries. The beginnings in the early 1950's centered on the Van de Graaff machine and linear accelerators and the pioneering efforts of Ethicon Inc. here in the United States must be recognized. However, although sterilization with electron beams is still current practice in a number of plants, the use of gamma rays from cobalt-60 is preferred. The first steps in this direction were taken by the U.K.A.E.A. which, in common with similar organizations elsewhere, was attempting to exploit the tremendous potential for cobalt-60 production arising through the rapid construction of nuclear reactors. The first full-scale commercial gamma plant was commissioned in the U.K. in 1960. It reached a loading of 500,000 curies before its demolition after twelve years of operation. The process gained rapid acceptance within industry and approval by health authorities because it provided a ''cold'' sterilization method combining the property of lethal effect with penetration. Its immediate impact occurred in the introduction of disposable products making it possible, for example, to use heat-labile plastics and new packaging materials and package designs. Certainly, the technique has proved complementary to sterilization methods based on heat and to the use of chemical agents, in particular ethylene oxide gas

  17. Influence of feedwater and blowdown systems on the mineral distribution in WWER steam generators

    International Nuclear Information System (INIS)

    Papp, L.

    1995-01-01

    After modification of Dukovany NPP steam generator (SG) feedwater system, the increased concentration of minerals was measured in the cold leg of modified SG. Some modifications were performed on operating WWER 1000 steam generators with aim to optimize the water chemistry in the collectors area. Since the distribution of minerals can substantially affect on corrosion processes in steam generators, VITKOVICE, as a producer of WWER steam generators has focused the attention to the optimizing of these systems. To predict the mineral distribution on the secondary side of steam generators for considered feedwater/blowdown systems, the simple model of the flow distribution in the secondary side of SG was developed

  18. Influence of feedwater and blowdown systems on the mineral distribution in WWER steam generators

    Energy Technology Data Exchange (ETDEWEB)

    Papp, L. [Inst. of Material Engineering, Ostrava (Switzerland)

    1995-12-31

    After modification of Dukovany NPP steam generator (SG) feedwater system, the increased concentration of minerals was measured in the cold leg of modified SG. Some modifications were performed on operating WWER 1000 steam generators with aim to optimize the water chemistry in the collectors area. Since the distribution of minerals can substantially affect on corrosion processes in steam generators, VITKOVICE, as a producer of WWER steam generators has focused the attention to the optimizing of these systems. To predict the mineral distribution on the secondary side of steam generators for considered feedwater/blowdown systems, the simple model of the flow distribution in the secondary side of SG was developed.

  19. The effect of tubal sterilization with the Pomeroy technique and bipolar electrocauterization on the ovarian reserve and serum anti-Müllerian hormone levels in a rat model.

    Science.gov (United States)

    Kaya, Cihan; Turgut, Hürriyet; Cengiz, Hüseyin; Turan, Ayşenur; Ekin, Murat; Yaşar, Levent

    2015-02-01

    To investigate the effects of tubal sterilization techniques on the ovarian reserve and serum anti-Müllerian hormone (AMH) levels in rats. Wistar Hannover rats (n=21) were assigned to the following 3 groups (7 rats/group): Pomeroy technique, bipolar electrocauterization, and control. Pre- and postoperative serum AMH levels, ovarian damage and ovarian follicle counts were assessed. Total ovarian damage was higher in the electrocauterization group than in the Pomeroy (p=0.008) and control (pPomeroy group than in the electrocauterization (p=0.023) and control (p=0.003) groups. The electrocauterization group had a greater decrease in postoperative serum AMH levels than the Pomeroy and control groups (p=0.031). Bipolar electrocauterization may have a negative effect on the ovarian structure and ovarian reserve compared to the Pomeroy technique. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  20. Steam-Generator Integrity Program/Steam-Generator Group Project

    International Nuclear Information System (INIS)

    1982-10-01

    The Steam Generator Integrity Program (SGIP) is a comprehensive effort addressing issues of nondestructive test (NDT) reliability, inservice inspection (ISI) requirements, and tube plugging criteria for PWR steam generators. In addition, the program has interactive research tasks relating primary side decontamination, secondary side cleaning, and proposed repair techniques to nondestructive inspectability and primary system integrity. The program has acquired a service degraded PWR steam generator for research purposes. This past year a research facility, the Steam Generator Examination Facility (SGEF), specifically designed for nondestructive and destructive examination tasks of the SGIP was completed. The Surry generator previously transported to the Hanford Reservation was then inserted into the SGEF. Nondestructive characterization of the generator from both primary and secondary sides has been initiated. Decontamination of the channelhead cold leg side was conducted. Radioactive field maps were established in the steam generator, at the generator surface and in the SGEF

  1. 45 CFR 96.73 - Sterilization.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Sterilization. 96.73 Section 96.73 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION BLOCK GRANTS Social Services Block Grants § 96.73 Sterilization. If a State authorizes sterilization as a family planning service, it must comply...

  2. Reversal of sterilization by microsurgical technique.

    Science.gov (United States)

    Gaspari, A L; Ortensi, A; Parlangeli, V; Pellizzari, G; Setti, C; Lania, M

    1988-01-01

    Tubal sterilization techniques that spare the fimbriae and cause the least amount of tubal destruction offer the best chance for reversal of sterilization. Patients seeking reversal of sterilization should be carefully selected. Surgical technique and equipment are important factors in reversal procedures; microsurgical techniques are shown to be more effective than macroscopic techniques.

  3. Steam generator materials

    International Nuclear Information System (INIS)

    Kim, Joung Soo; Han, J. H.; Kim, H. P.; Lim, Y. S.; Lee, D. H.; Suh, J. H.; Hwang, S. S.; Hur, D. H.; Kim, D. J.; Kim, Y. H.

    2002-05-01

    In order to keep the nuclear power plant(NPP)s safe and increase their operating efficiency, axial stress corrosion cracking(SCC)(IGA/IGSCC, PWSCC, PbSCC) test techniques were developed and SCC property data of the archive steam generator tubing materials having been used in nuclear power plants operating in Korea were produced. The data obtained in this study were data-based, which will be used to clarify the damage mechanisms, to operate the plants safely, and to increase the lifetime of the tubing. In addition, the basic technologies for the improvement of the SCC property of the tubing materials, for new SCC inhibition, for damaged tube repair, and for manufacturing processes of the tubing were developed. In the 1 phase of this long term research, basic SCC test data obtained from the archive steam generator tubing materials used in NPPs operating in Korea were established. These basic technologies developed in the 1 phase will be used in developing process optimization during the 2 phase in order to develop application technologies to the field nuclear power plants

  4. On the gasification of biomass in a steam-oxygen blown CFB gasifier with the focus on gas quality upgrading : Technology background, experiments and mathematical modeling

    NARCIS (Netherlands)

    Siedlecki, M.

    2011-01-01

    This work presents and discusses the results of the research on the gasification of biomass in an atmospheric circulating fluidized bed, with a mixture of steam and oxygen as fluidization / gasification medium. The main objectives of this research were to investigate and improve the gasification

  5. A nodalization study of steam separator in real time simulation

    International Nuclear Information System (INIS)

    Horugshyang, Lein; Luh, R.T.J.; Zen-Yow, Wang

    1999-01-01

    The motive of this paper is to investigate the influence of steam separator nodalization on reactor thermohydraulics in terms of stability and level response. Three different nodalizations of steam separator are studied by using THEATRE and REMARK Code in a BWR simulator. The first nodalization is the traditional one with two nodes for steam separator. In this nodalization, the steam separation is modeled in the outer node, i.e., upper downcomer. Separated steam enters the Steen dome node and the liquid goes to the feedwater node. The second nodalization is similar to the first one with the steam separation modeled in the inner node. There is one additional junction connecting steam dome node and the inner node. The liquid fallback junction connects the inner node and feedwater node. The third nodalization is a combination of the former two with an integrated node for steam separator. Boundary conditions in this study are provided by a simplified feedwater and main steam driver. For comparison purpose, three tests including full power steady state initialisation, recirculation pumps runback and reactor scram are conducted. Major parameters such as reactor pressure, reactor level, void fractions, neutronic power and junction flows are recorded for analysis. Test results clearly show that the first nodalization is stable for steady state initialisation. However it has too responsive level performance in core flow reduction transients. The second nodalization is the closest representation of real plant structure, but not the performance. Test results show that an instability occurs in the separator region for both steady state initialisation and transients. This instability is caused by an unbalanced momentum in the dual loop configuration. The magnitude of the oscillation reduces as the power decreases. No superiority to the other nodalizations is shown in the test results. The third nodalization shows both stability and responsiveness in the tests. (author)

  6. Genetic optimization of steam multi-turbines system

    International Nuclear Information System (INIS)

    Olszewski, Pawel

    2014-01-01

    Optimization analysis of partially loaded cogeneration, multiple-stages steam turbines system was numerically investigated by using own-developed code (C++). The system can be controlled by following variables: fresh steam temperature, pressure, and flow rates through all stages in steam turbines. Five various strategies, four thermodynamics and one economical, which quantify system operation, were defined and discussed as an optimization functions. Mathematical model of steam turbines calculates steam properties according to the formulation proposed by the International Association for the Properties of Water and Steam. Genetic algorithm GENOCOP was implemented as a solving engine for non–linear problem with handling constrains. Using formulated methodology, example solution for partially loaded system, composed of five steam turbines (30 input variables) with different characteristics, was obtained for five strategies. The genetic algorithm found multiple solutions (various input parameters sets) giving similar overall results. In real application it allows for appropriate scheduling of machine operation that would affect equable time load of every system compounds. Also based on these results three strategies where chosen as the most complex: the first thermodynamic law energy and exergy efficiency maximization and total equivalent energy minimization. These strategies can be successfully used in optimization of real cogeneration applications. - Highlights: • Genetic optimization model for a set of five various steam turbines was presented. • Four various thermodynamic optimization strategies were proposed and discussed. • Operational parameters (steam pressure, temperature, flow) influence was examined. • Genetic algorithm generated optimal solutions giving the best estimators values. • It has been found that similar energy effect can be obtained for various inputs

  7. Microwave Sterilization and Depyrogenation System

    Science.gov (United States)

    Akse, James R.; Dahl, Roger W.; Wheeler, Richard R., Jr.

    2009-01-01

    A fully functional, microgravity-compatible microwave sterilization and depyrogenation system (MSDS) prototype was developed that is capable of producing medical-grade water (MGW) without expendable supplies, using NASA potable water that currently is available aboard the International Space Station (ISS) and will be available for Lunar and planetary missions in the future. The microwave- based, continuous MSDS efficiently couples microwaves to a single-phase, pressurized, flowing water stream that is rapidly heated above 150 C. Under these conditions, water is rapidly sterilized. Endotoxins, significant biological toxins that originate from the cell walls of gram-negative bacteria and which represent another defining MGW requirement, are also deactivated (i.e., depyrogenated) albeit more slowly, with such deactivation representing a more difficult challenge than sterilization. Several innovations culminated in the successful MSDS prototype design. The most significant is the antenna-directed microwave heating of a water stream flowing through a microwave sterilization chamber (MSC). Novel antenna designs were developed to increase microwave transmission efficiency. These improvements resulted in greater than 95-percent absorption of incident microwaves. In addition, incorporation of recuperative heat exchangers (RHxs) in the design reduced the microwave power required to heat a water stream flowing at 15 mL/min to 170 C to only 50 W. Further improvements in energy efficiency involved the employment of a second antenna to redirect reflected microwaves back into the MSC, eliminating the need for a water load and simplifying MSDS design. A quick connect (QC) is another innovation that can be sterilized and depyrogenated at temperature, and then cooled using a unique flow design, allowing collection of MGW at atmospheric pressure and 80 C. The final innovation was the use of in-line mixers incorporated in the flow path to disrupt laminar flow and increase contact time

  8. Prediction and modeling of the two-dimensional separation characteristic of a steam generator at a nuclear power station with VVER-1000 reactors

    Science.gov (United States)

    Parchevsky, V. M.; Guryanova, V. V.

    2017-01-01

    A computational and experimental procedure for construction of the two-dimensional separation curve (TDSC) for a horizontal steam generator (SG) at a nuclear power station (NPS) with VVER-reactors. In contrast to the conventional one-dimensional curve describing the wetness of saturated steam generated in SG as a function of the boiler water level at one, usually rated, load, TDSC is a function of two variables, which are the level and the load of SGB that enables TDSC to be used for wetness control in a wide load range. The procedure is based on two types of experimental data obtained during rated load operation: the nonuniformity factor of the steam load at the outlet from the submerged perforated sheet (SPS) and the dependence of the mass water level in the vicinity of the "hot" header on the water level the "cold" end of SG. The TDSC prediction procedure is presented in the form of an algorithm using SG characteristics, such as steam load and water level as the input and giving the calculated steam wetness at the output. The zoneby-zone calculation method is used. The result is presented in an analytical form (as an empirical correlation) suitable for uploading into controllers or other controls. The predicted TDSC can be used during real-time operation for implementation of different wetness control scenarios (for example, if the effectiveness is a priority, then the minimum water level, minimum wetness, and maximum turbine efficiency should be maintained; if safety is a priority, then the maximum level at the allowable wetness and the maximum water inventory should be kept), for operation of NPS in controlling the frequency and power in a power system, at the design phase (as a part of the simulation complex for verification of design solutions), during construction and erection (in developing software for personnel training simulators), during commissioning tests (to reduce the duration and labor-intensity of experimental activities), and for training.

  9. Heat exchanger with steam overheating

    International Nuclear Information System (INIS)

    Manek, O.; Motejl, V.; Quitta, R.; Schlinger, S.

    1975-01-01

    A heat exchanger incorporating steam superheating is proposed suitable for nuclear power plants having heat transfer surfaces housed in the pressure vessel. The heat exchanger is characterized by the fact that on the primary side the steam overheating surface is parallel to the afterheating and evaporating surfaces. The parallel heat transfer surfaces, afterheating and evaporating surfaces are connected to a common tube plate. The superheated steam outlet is formed by the central tube, the saturated steam by-pass channel is formed by a concentric tube. The steam superheating surface is formed by a cluster of U-tubes. Spatial U-tubes form the afterheating and the evaporating surfaces outside of the superheating surface. (Oy)

  10. Steam generator reliability improvement project

    International Nuclear Information System (INIS)

    Blomgren, J.C.; Green, S.J.

    1987-01-01

    Upon successful completion of its research and development technology transfer program, the Electric Power Research Institute's Steam Generator Owners Group (SGOG II) will disband in December 1986 and be replaced in January 1987 by a successor project, the Steam Generator Reliability Project (SGRP). The new project, funded in the EPRI base program, will continue the emphasis on reliability and life extension that was carried forward by SGOG II. The objectives of SGOG II have been met. Causes and remedies have been identified for tubing corrosion problems, such as stress corrosion cracking and pitting, and steam generator technology has been improved in areas such as tube wear prediction and nondestructive evaluation (NDE). These actions have led to improved reliability of steam generators. Now the owners want to continue with a centrally managed program that builds on what has been learned. The goal is to continue to improve steam generator reliability and solve small problems before they become large problems

  11. Steam generator reliability improvement project

    International Nuclear Information System (INIS)

    Blomgren, J.C.; Green, S.J.

    1987-01-01

    Upon successful completion of its research and development technology transfer program, the Electric Power Research Institute's (EPRI's) Steam Generator Owners Group (SGOG II) will disband in December 1986, and be replaced in January 1987, by a successor project, the Steam Generator Reliability Project (SGRP). The new project, funded in the EPRI base program, will continue to emphasize reliability and life extension, which were carried forward by SGOG II. The objectives of SGOG II have been met. Causes and remedies have been identified for tubing corrosion problems such as stress corrosion cracking and pitting, and steam generator technology has been improved in areas such as tube wear prediction and nondestructive evaluation. These actions have led to improved reliability of steam generators. Now the owners want to continue with a centrally managed program that builds on what has been learned. The goal is to continue to improve steam generator reliability and to solve small problems before they become large problems

  12. Modelagem de um reator integral aplicado na reação de reforma a vapor de metano = Modeling of integral reactor applied methane steam reforming

    Directory of Open Access Journals (Sweden)

    Giane Gonçalves

    2007-07-01

    Full Text Available Freqüentemente, a validação de modelos matemáticos aplicados a reatores industriais esbarra na dificuldade de obtenção de medidas experimentais confiáveis. Uma maneira de contornar esta limitação corresponde à implantação de uma unidade em escala de bancada devidamente instrumentada, na qual são obtidos dados experimentais emcondições controladas. Neste contexto, foram efetuados ensaios em um reator integral de reforma a vapor de metano em escala de bancada, em diversas condições experimentais. As medidas de temperatura no leito foram efetuadas por meio de um termopar multiponto em seis posições axiais distintas, enquanto a composição do efluente do reator foi determinada por cromatografia gasosa. Estes dados experimentais foram comparados com as previsões de um modelo pseudo-homogêneo, unidimensional e dinâmico. Os resultados indicam que o modelo é adequado, sendo que tanto a atividade catalítica como a conversão são sensíveis à temperatura operacional, enquanto a temperatura do leito é praticamente insensível à vazão nas condições experimentais exploradas.Frequently, the validation of applied mathematical models of industrial reactors dash into the difficulty of obtaining reliable experimental data. A way to overcome this limitation is the proper use and operation or a in bench scale, experimental setup from whichexperimental data can be obtained in controlled conditions. In this context, experiments were carried out in an integral reactor of steam reform, in different experimental conditions. Thermocouples were placed along the catalyst bed to allow for temperature monitoring in six equally spaced and distinct positions of the reactor, the composition of the effluent of the reactor was determined by gas chromatography. These experimental data were compared with the theoretical results of a pseudo-homogeneous one-dimensional,dynamic mathematical model. The results indicate that the model can successfully

  13. Steam generators of PWRs and plan of replacing steam generators

    International Nuclear Information System (INIS)

    Dodo, Takashi; Matsushita, Kiyohiko.

    1995-01-01

    Also in Japan, the plan of replacing steam generators which are one of most important equipments of PWRs is being advanced. In this report, the whole circumstances of the plan of replacing steam generators, such as the background that necessitated the replacement, the concrete plan of the replacement, the results of the replacement in foreign countries and others, are described in general. The function of steam generators is to form a part of the pressure boundary for confining reactor primary coolant, and to generate steam by the heat exchange between primary and secondary coolants. The basic structure is a shell and tube type heat exchanger having vertically installed, inverse U shape tubes, in which primary coolant flows. In Japan as of December, 1994, 22 PWR plants of 18,186 million kW output were in operation. The management of steam generators and the background of their replacement due to the fear of public about heating tube leak, the enormous cost of the inspection and repair, the restriction of power system operation and others are explained. As for the steam generators of Takahama No. 2, Oi No. 1 and Genkai No. 1 plants, the application for the replacement was made, and the breakdown of a tube occurred in Mihama No. 2 plant. The replacement of steam generators in Japan and foreign countries is reported. (K.I.)

  14. Sterility of the uterine cavity

    DEFF Research Database (Denmark)

    Møller, Birger R.; Kristiansen, Frank V.; Thorsen, Poul

    1995-01-01

    In a prospective open study the sterility of the uterine cavity was evaluated in 99 women admitted for hysterectomy. The indications for hysterectomy were in most cases persistent irregular vaginal bleeding and fibromyomas of the uterus. Samples for both aerobic and anaerobic bacteria, Chlamydia ...... which may play a causative role in endometritis. The results indicate that inflammation of the uterine cavity should be evaluated by hysteroscopic examination before hysterectomy is undertaken in patients with persistent irregular vaginal bleeding. Udgivelsesdato: 1995-Mar...

  15. Catalytic steam reforming of bio-oil

    DEFF Research Database (Denmark)

    Trane, R.; Dahl, S.; Skjøth-Rasmussen, M.S.

    2012-01-01

    Hydrogen and synthesis gas can be produced in an environmentally friendly and sustainable way through steam reforming (SR) of bio-oil and this review presents the state-of-the-art of SR of bio-oil and model compounds hereof. The possible reactions, which can occur in the SR process and the influe......Hydrogen and synthesis gas can be produced in an environmentally friendly and sustainable way through steam reforming (SR) of bio-oil and this review presents the state-of-the-art of SR of bio-oil and model compounds hereof. The possible reactions, which can occur in the SR process...... and the influence of operating conditions will be presented along with the catalysts and processes investigated in the literature.Several catalytic systems with Ni, Ru, or Rh can achieve good performance with respect to initial conversion and yield of hydrogen, but the main problem is that the catalysts...

  16. Integration of torrefaction with steam power plant

    Energy Technology Data Exchange (ETDEWEB)

    Zakri, B.; Saari, J.; Sermyagina, E.; Vakkilainen, E.

    2013-09-01

    Torrefaction is one of the pretreatment technologies to enhance the fuel characteristics of biomass. The efficient and continuous operation of a torrefaction reactor, in the commercial scale, demands a secure biomass supply, in addition to adequate source of heat. Biorefinery plants or biomass-fuelled steam power plants have the potential to integrate with the torrefaction reactor to exchange heat and mass, using available infrastructure and energy sources. The technical feasibility of this integration is examined in this study. A new model for the torrefaction process is introduced and verified by the available experimental data. The torrefaction model is then integrated in different steam power plants to simulate possible mass and energy exchange between the reactor and the plants. The performance of the integrated plant is investigated for different configurations and the results are compared. (orig.)

  17. Biosorptive uptake of ibuprofen by steam activated biochar derived from mung bean husk: Equilibrium, kinetics, thermodynamics, modeling and eco-toxicological studies.

    Science.gov (United States)

    Mondal, Sandip; Bobde, Kiran; Aikat, Kaustav; Halder, Gopinath

    2016-11-01

    The present study explores the use of steam activated mung bean husk biochar (SA-MBHB) as a potential sorbent for the removal of non-steroidal and anti-inflammatory drug ibuprofen from aqueous solution. SA-MBHB was characterized by SEM, FTIR, BET, TGA, point of zero charge (pHPZC) and UV-Vis spectrophotometer. The relation between removal percentages of ibuprofen and parameters such as adsorbent dose (0.05 g-250 g), contact time (5 min-210 min), pH (2-10), speed of agitation (40-280 rpm), temperature (293-308 K) and initial ibuprofen concentration (5-100 ppm) was investigated and optimized by a series of batch sorption experiments. The optimized conditions achieved were: adsorbent dose 0.1 g/L, agitation speed 200 rpm, pH 2, initial ibuprofen concentration 20 mg L(-1), equilibrium time 120 min and temperature 20 °C for more than 99% adsorptive removal of ibuprofen. The equilibrium adsorption data were well fitted into the Langmuir isotherm model while kinetic data suggested the removal process to follow pseudo second order reaction. The adsorption phenomena were optimized and simulated by using response surface methodology (RSM) and artificial neural network (ANN). Effect of process variables viz. dose, agitation speed and pH on the sorbed amount of IBP was studied through a 2(3) full factorial central composite design (CCD). The comparative analysis was done for ibuprofen removal by constructing ANN model training using same experimental matrix of CCD. The growth of Scenedesmus abundans was also observed to be affected by the IBP solution whereas the biochar treated with IBP solution did not significantly affect the growth of the Scenedesmus abundans. The results revealed that SA-MBHB could be a cost-effective, efficient and non-hazardous adsorbent for the removal of ibuprofen from aqueous solution. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. MINET validation study using steam generator test data

    International Nuclear Information System (INIS)

    Van Tuyle, G.J.; Guppy, J.G.

    1984-01-01

    Three steam generator transient test cases that were simulated using the MINET computer code are described, with computed results compared against experimental data. The MINET calculations closely agreed with the experiment for both the once-through and the U-tube steam generator test cases. The effort is part of an ongoing effort to validate the MINET computer code for thermal-hydraulic plant systems transient analysis, and strongly supports the validity of the MINET models

  19. Steam generator accident protection

    International Nuclear Information System (INIS)

    Matal, O.; Martoch, J.

    1986-01-01

    The outbreak of an accident in separate heat exchange unit of a steam generator (all the heat exchange units being connected to an alkali metal circuit) will activate a stop valve and a relief valve. The two valves are placed at the input and output pipes of the damaged unit. The same valves will also close after a very short time the inflow of metal into the disturbed heat exchange unit and this will immediately, without any pressure shock, pipe the metal into an equalizer tank; they will also close the outflow of metal which together with the reaction products will be piped into the discharge tank. At the same time the stop valves on the feed water pipe are closed. The whole equipment shows excellent coordination and has standby elements which are put into operation when any of the elements fail. The failed unit is thus safely separated from the other units and may be independently repaired. (J.B.)

  20. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1983-08-01

    A review of the performance of steam generator tubes in 110 water-cooled nuclear power reactors showed that tubes were plugged at 46 (42 percent) of the reactors. The number of tubes removed from service increased from 1900 (0.14 percent) in 1980 to 4692 (0.30 percent) in 1981. The leading causes of tube failures were stress corrosion cracking from the primary side, stress corrosion cracking (or intergranular attack) from the secondary side and pitting corrosion. The lowest incidence of corrosion-induced defects from the secondary side occurred in reactors that used all-volatile treatment since start-up. At one reactor a large number of degraded tubes were repaired by sleeving which is expected to become an important method of tube repair in the future

  1. Steam generator tube performance

    International Nuclear Information System (INIS)

    Tatone, O.S.; Pathania, R.S.

    1982-04-01

    The performance of steam generator tubes in water-cooled nuclear power reactors has been reviewed for 1980. Tube defects occurred at 38% of the 97 reactors surveyed. This is a marginal improvement over 1979 when defects occurred at 41% of the reactors. The number of failed tubes was also lower, 0.14% of the tubes in service in 1980 compared with 0.20% of those in service in 1979. Analysis of the causes of these failures indicates that stress corrosion cracking was the leading failure mechanism. Reactors that used all-volatile treatment of secondary water, with or without full-flow condensate demineralization since start-up showed the lowest incidence of corrosion-related defects

  2. Condensation of the steam in the horizontal steam line during cold water flooding

    International Nuclear Information System (INIS)

    Strubelj, L.; Tiselj, I.

    2006-01-01

    Direct contact condensation and condensation induced water-hammer in a horizontal pipe was experimentally investigated at PMK-2 test facility of the Hungarian Atomic Energy Research Institute KFKI. The experiment is preformed in the horizontal section of the steam line of the PMK-2 integral test facility. As liquid water floods the horizontal part of the pipeline, the counter current horizontally stratified flow is being observed. During the flooding of the steam line, the vapour-liquid interface area increases and therefore the vapour condensation rate and the vapour velocity also increase. Similar phenomena can occur in the cold/hot leg of the primary loop of PWR nuclear power plant during loss of coolant accident, when emergency core cooling system is activated. Water level at one cross-section and four local void fraction and temperature at the top of steam line was measured and compared with simulation. Condensed steam increases the water temperature that is why the local temperature measurements are the most important information, from which condensation rate can be estimated, since mass of condensed steam was not measured. Free surface simulation of the experiment with thermal phase change model is presented. Surface renewal concept with small eddies is used for calculation of heat transfer coefficient. With surface renewal theory we did not get results similar to experiment, that is why heat transfer coefficient was increased by factor 20. In simulation with heat transfer coefficient calculated with surface renewal concept bubble entrapment is due to reflection of the wave from the end of the pipe. When heat transfer coefficient is increased, condensation rate and steam velocity are also increased, bubble entrapment is due to Kelvin-Helmholtz instability of the free surface, and the results become similar to the measurements. (author)

  3. Closing in on resonantly produced sterile neutrino dark matter

    Science.gov (United States)

    Cherry, John F.; Horiuchi, Shunsaku

    2017-04-01

    We perform an exhaustive scan of the allowed resonant production regime for sterile neutrino dark matter in order to improve constraints for dark matter structures which arise from the nonthermal sterile neutrino energy spectra. Small-scale structure constraints are particularly sensitive to large lepton asymmetries/small mixing angles which result in relatively warmer sterile neutrino momentum distributions. We revisit Milky Way galaxy subhalo count constraints and combine them with recent searches for x-ray emission from sterile neutrino decays. Together, they rule out models outside the mass range 7.0 keV ≤mνs≤36 keV and lepton asymmetries smaller than 15 ×10-6 per unit entropy density at 95% confidence interval or greater. We also find that, while a portion of the parameter space remains unconstrained, the combination of subhalo counts and x-ray data indicates the candidate 3.55 keV x-ray line signal potentially originating from a 7.1 keV sterile neutrino decay to be disfavored at 93% confidence interval.

  4. CANDU steam generator life management

    Energy Technology Data Exchange (ETDEWEB)

    Tapping, R.L. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Nickerson, J. [Atomic Energy of Canada Limited, Mississauga, Ontario (Canada); Spekkens, P.; Maruska, C. [Ontario Hydro, Toronto, Ontario (Canada)

    1998-01-01

    Steam generators are a critical component of a nuclear power reactor, and can contribute significantly to station unavailability, as has been amply demonstrated in Pressurized Water Reactors (PWRs). CANDU steam generators are not immune to steam generator degradation, and the variety of CANDU steam generator designs and tube materials has led to some unexpected challenges. However, aggressive remedial actions, and careful proactive maintenance activities, have led to a decrease in steam generator-related station unavailability of Canadian CANDUs. AECL and the CANDUutilities have defined programs that will enable existing or new steam generators to operate effectively for 40 years. Research and development work covers corrosion and mechanical degradation of tube bundles and internals, chemistry, thermalhydraulics, fouling, inspection and cleaning, as well as provision for specially tool development for specific problem solving. A major driving force is development of CANDU-specific fitness-for-service guidelines, including appropriate inspection and monitoring technology to measure steam generator condition. Longer-range work focuses on development of intelligent on-line monitoring for the feedwater system and steam generator. New designs have reduced risk of corrosion and fouling, are more easily inspected and cleaned, and are less susceptible to mechanical damage. The Canadian CANDU utilities have developed programs for remedial actions to combat degradation of performance (Gentilly-2, Point Lepreau, Bruce A/B, Pickering A/B), and have developed strategic plans to ensure that good future operation is ensured. The research and development program, as well as operating experience, has identified where improvements in operating practices and/or designs can be made in order to ensure steam generator design life at an acceptable capacity factory. (author)

  5. Thermodynamic properties of dissociated steam

    Science.gov (United States)

    Aminov, R. Z.; Gudym, A. A.

    2017-11-01

    In connection with the development of hydrogen technologies and the generation of dissociated steam as a result of the oxidation of hydrogen in an oxygen environment, it became necessary to determine the calorific parameters of dissociated steam. In the existing tables, the caloric parameters of dissociated steam are presented at a reference temperature of 0 K. By contrast, the authors have developed tables of dissociated steam using a reference temperature of 0°C, within the pressure range 0.01–20.0 MPa and the temperature range 1250–4000 K, along with a system of equations for the industrial calculation of the properties of dissociated steam within the temperature range 1250–2300 K and pressure range 0.01–10.0 MPa, followed by a temperature range of 2200–3600 K. During the dissociation of steam, a mixture of eight components are formed including hydrogen H, oxygen O, radicals OH and HO2, molecules of hydrogen H2, oxygen O2, steam H2O, and hydrogen peroxide H2O2. All existing tables of the properties of dissociated steam are based on a mixture of six components: H2, O2, OH, H, O, and H2O. For evaluate whether this is an oversimplification, the composition of the mixture comprising all eight components was calculated, taking into account additional chemical reactions for the formation of HO2 and H2O2. At a pressure of 0.01 MPa, the maximum mole fraction of HO2 was 2.8·10‑5 at a temperature of 3000 K, and at a pressure of 10 MPa, the maximum mole fraction was 5·10‑5 at a temperature of 4000 K. The mole fraction of H2O2 was much lower. Thus at temperatures up to 3000 K, calculations of the properties of dissociated steam are restricted to six components.

  6. CANDU steam generator life management

    International Nuclear Information System (INIS)

    Tapping, R.L.; Nickerson, J.; Spekkens, P.; Maruska, C.

    1998-01-01

    Steam generators are a critical component of a nuclear power reactor, and can contribute significantly to station unavailability, as has been amply demonstrated in Pressurized Water Reactors (PWRs). CANDU steam generators are not immune to steam generator degradation, and the variety of CANDU steam generator designs and tube materials has led to some unexpected challenges. However, aggressive remedial actions, and careful proactive maintenance activities, have led to a decrease in steam generator-related station unavailability of Canadian CANDUs. AECL and the CANDU utilities have defined programs that will enable existing or new steam generators to operate effectively for 40 years. Research and development work covers corrosion and mechanical degradation of tube bundles and internals, chemistry, thermalhydraulics, fouling, inspection and cleaning, as well as provision for specially tool development for specific problem solving. A major driving force is development of CANDU-specific fitness-for-service guidelines, including appropriate inspection and monitoring technology to measure steam generator condition. Longer-range work focuses on development of intelligent on-line monitoring for the feedwater system and steam generator. New designs have reduced risk of corrosion and fouling, are more easily inspected and cleaned, and are less susceptible to mechanical damage. The Canadian CANDU utilities have developed programs for remedial actions to combat degradation of performance (Gentilly-2, Point Lepreau, Bruce A/B, Pickering A/B), and have developed strategic plans to ensure that good future operation is ensured. The research and development program, as well as operating experience, has identified where improvements in operating practices and/or designs can be made in order to ensure steam generator design life at an acceptable capacity factory. (author)

  7. Sterile neutrino portal to Dark Matter II: exact dark symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Escudero, Miguel; Rius, Nuria [Universidad de Valencia-CSIC, Departamento de Fisica Teorica and IFIC, C/Catedratico Jose Beltran, 2, 46980, Paterna (Spain); Sanz, Veronica [University of Sussex, Department of Physics and Astronomy, Brighton (United Kingdom)

    2017-06-15

    We analyze a simple extension of the standard model (SM) with a dark sector composed of a scalar and a fermion, both singlets under the SM gauge group but charged under a dark sector symmetry group. Sterile neutrinos, which are singlets under both groups, mediate the interactions between the dark sector and the SM particles, and generate masses for the active neutrinos via the seesaw mechanism. We explore the parameter space region where the observed Dark Matter relic abundance is determined by the annihilation into sterile neutrinos, both for fermion and scalar Dark Matter particles. The scalar Dark Matter case provides an interesting alternative to the usual Higgs portal scenario. We also study the constraints from direct Dark Matter searches and the prospects for indirect detection via sterile neutrino decays to leptons, which may be able to rule out Dark Matter masses below and around 100 GeV. (orig.)

  8. Displaced vertex searches for sterile neutrinos at future lepton colliders

    Energy Technology Data Exchange (ETDEWEB)

    Antusch, Stefan [Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel (Switzerland); Max-Planck-Institut für Physik (Werner-Heisenberg-Institut),Föhringer Ring 6, D-80805 München (Germany); Cazzato, Eros; Fischer, Oliver [Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel (Switzerland)

    2016-12-02

    We investigate the sensitivity of future lepton colliders to displaced vertices from the decays of long-lived heavy (almost sterile) neutrinos with electroweak scale masses and detectable time of flight. As future lepton colliders we consider the FCC-ee, the CEPC, and the ILC, searching at the Z-pole and at the center-of-mass energies of 240, 350 and 500 GeV. For a realistic discussion of the detector response to the displaced vertex signal and the Standard Model background we consider the ILC’s Silicon Detector (SiD) as benchmark for the future lepton collider detectors. We find that displaced vertices constitute a powerful search channel for sterile neutrinos, sensitive to squared active-sterile mixing angles as small as 10{sup −11}.

  9. Experimental and theoretical investigations on safety of the SNR - straight-tube design steam generator with sodium-water reactions

    International Nuclear Information System (INIS)

    Dumm, K.; Sauermann, F.; Schnitker, W.; Welter, A.

    A number of large sodium-water reaction tests has been performed in a steam generator model in order to verify the layout criteria of the SNR straight-tube design steam generators under accident conditions. The experimental setup is described. The test results and their applicability to the SNR steam generators are given and discussed. (U.S.)

  10. Steam reformer with catalytic combustor

    Science.gov (United States)

    Voecks, Gerald E. (Inventor)

    1990-01-01

    A steam reformer is disclosed having an annular steam reforming catalyst bed formed by concentric cylinders and having a catalytic combustor located at the center of the innermost cylinder. Fuel is fed into the interior of the catalytic combustor and air is directed at the top of the combustor, creating a catalytic reaction which provides sufficient heat so as to maintain the catalytic reaction in the steam reforming catalyst bed. Alternatively, air is fed into the interior of the catalytic combustor and a fuel mixture is directed at the top. The catalytic combustor provides enhanced radiant and convective heat transfer to the reformer catalyst bed.

  11. Wet-steam erosion of steam turbine disks and shafts

    International Nuclear Information System (INIS)

    Averkina, N. V.; Zheleznyak, I. V.; Kachuriner, Yu. Ya.; Nosovitskii, I. A.; Orlik, V. G.; Shishkin, V. I.

    2011-01-01

    A study of wet-steam erosion of the disks and the rotor bosses or housings of turbines in thermal and nuclear power plants shows that the rate of wear does not depend on the diagrammed degree of moisture, but is determined by moisture condensing on the surfaces of the diaphragms and steam inlet components. Renovating the diaphragm seals as an assembly with condensate removal provides a manifold reduction in the erosion.

  12. Plasma Sterilization: New Epoch in Medical Textiles

    Science.gov (United States)

    Senthilkumar, P.; Arun, N.; Vigneswaran, C.

    2015-04-01

    Clothing is perceived to be second skin to the human body since it is in close contact with the human skin most of the times. In hospitals, use of textile materials in different forms and sterilization of these materials is an essential requirement for preventing spread of germs. The need for appropriate disinfection and sterilization techniques is of paramount importance. There has been a continuous demand for novel sterilization techniques appropriate for use on various textile materials as the existing sterilization techniques suffer from various technical and economical drawbacks. Plasma sterilization is the alternative method, which is friendlier and more effective on the wide spectrum of prokaryotic and eukaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species. Plasma exposure can kill micro-organisms on a surface in addition to removing adsorbed monolayer of surface contaminants. Advantages of plasma surface treatment are removal of contaminants from the surface, change in the surface energy and sterilization of the surface. Plasma sterilization aims to kill and/or remove all micro-organisms which may cause infection of humans or animals, or which can cause spoilage of foods or other goods. This review paper emphasizes necessity for sterilization, essentials of sterilization, mechanism of plasma sterilization and the parameters influencing it.

  13. Women plan condom use after sterilization.

    Science.gov (United States)

    1998-12-01

    Sexual sterilization is highly effective in preventing pregnancy, but it does not protect against sexually transmitted diseases (STDs). People who accept sterilization as their method of family planning therefore need to be encouraged to protect themselves against HIV/AIDS and STDs even after they have been sterilized. Since women return less often to family planning providers following their sterilization procedure, they need to be advised to protect themselves against HIV and STDs before the sterilization is performed. 42% of the 2782 women who underwent tubal sterilizations at the Baylor College of Medicine in Houston during 1991-96 indicated their intention in a cross-sectional study to use condoms after sterilization. 20% of all respondents, aged 18-51 years, had a known risk factor for HIV, and almost 25% reported regular condom use for contraception or disease protection during the 3 months before sterilization. Planned condom use increased from 32% in 1991 to 51% in 1996, irrespective of age, marital status, or ethnic background. Of the 646 women who used condoms before being sterilized, almost half indicated no plans to do so after the procedure. The following factors were associated with condom use: relatively younger age, black ethnicity, unmarried status, history of previous STD, no steady partner, having a higher number of previous sex partners, past use of condoms to prevent disease transmission, and lack of partner involvement in the decision to undergo sterilization.

  14. Regret following female sterilization in Slovenia.

    Science.gov (United States)

    Becner, Anja; Turkanović, Anela Bečić; But, Igor

    2015-07-01

    To estimate the regret rate and risk factors for regret among women who have undergone sterilization. A retrospective study was conducted among all women who underwent a sterilization procedure at the University Medical Center Maribor, Maribor, Slovenia, in 2008-2012. Identified women were contacted and asked to complete an online questionnaire assessing regret and symptoms associated with depression. Among 714 identified women, 308 (43.1%) completed the questionnaire. Four (1.3%) participants reported regret, and 9 (2.9%) reported that they would not opt for sterilization again, all of whom had post-sterilization problems. Such problems were significantly associated with participants reporting that they would not opt for sterilization again (P=0.003). Additionally, women who would not choose sterilization again had significantly higher scores on the depressive scale used than did those who would undergo sterilization again (P=0.028). Few women report regret after tubal sterilization in Slovenia. However, an additional consultation on post-sterilization problems and depressive disorder before sterilization might minimize the risk of regret. Copyright © 2015 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

  15. Improvement of the MSG code for the MONJU evaporators. Additional function of reverse flow calculation on water/steam model and animation for post processing

    International Nuclear Information System (INIS)

    Toda, Shin-ichi; Yoshikawa, Shinji; Oketani, Kazuhiro

    2003-05-01

    The improved version of the MSG code (Multi-dimensional Thermal-hydraulic Analysis Code for Steam Generators) has been released. It has been carried out to improve based on the original version in order to calculate reverse flow on water/steam side, and to animate the post-processing data. To calculate reverse flow locally, modification to set pressure at each divided node point of water/steam region in the helical-coil heat transfer tubes has been carried out. And the matrix solver has been also improved to treat a problem within practical calculation time against increasing the pressure points. In this case pressure and enthalpy have to be calculated simultaneously, however, it was found out that using the block-Jacobean method make a diagonal-dominant matrix, and solve the matrix efficiently with a relaxation method. As the result of calculations of a steady-state condition and a transient of SG blow down with manual trip operation, the improvement on calculation function of the MSG code was confirmed. And an animation function of temperature contour in the sodium shell side as a post processing has been added. Since the animation is very effective to understand thermal-hydraulic behavior on the sodium shell side of the SG, especially in case of transient condition, the analysis and evaluation of the calculation results will be enabled to be more quickly and effectively. (author)

  16. Hydraulic model of the steam-lines network of the Cerro Prieto, B.C., geothermal field; Modelo hidraulico de la red de vaporductos del campo geotermico de Cerro Prieto, B.C.

    Energy Technology Data Exchange (ETDEWEB)

    Salaices, E; Garcia, A; Martinez J I; Ovando, R; Cecenas, M; Hernandez A F [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)]. E-mail: salaices@iie.org.mx; Canchola, I; Mora, O; Miranda, C; Herandez, M; Lopez, S; Murillo, I [Comision Federal de Electricidad, B.C (Mexico)

    2007-01-15

    The steam-line network of the Cerro Prieto geothermal field is composed of 184 wells, and 162 of the wells are integrated and connected by pipes. Thirteen power units, with an installed electrical capacity of 720 MW, are fed by that network. The network length is 120 km, including pipes of several diameters with branches and interconnections. The extension and complexity of the steam-line system make it difficult to analyze the transport and supply of steam to the power plants. For that it was necessary to have a tool capable of analyzing the system and the performance of the network as a whole, as well as the direction and flow volumes in each part of the system. In this paper, a hydraulic model of the Cerro Prieto steam-line network is presented. The model can determine the performance of the whole network by quantifying the pressure drops, flows and heat losses of the components. The model analyses the consequences of changes in operating conditions, steam production, maintenance activities and design (such as the integration of new wells). The model was developed using PIPEPHASE 9.0, a numeric simulator of multi-phase flow in steady state with heat transfer. It is used to model systems and pipe networks for steam- and condensate-transport. [Spanish] La red de vaporductos del campo geotermico de Cerro Prieto esta compuesta por un conjunto de 184 pozos, de los cuales 162 son pozos integrados, interconectados entre si a traves de una red de tuberias. Por medio de esta red se alimentan 13 unidades generadoras de electricidad con una capacidad total instalada de 720 MWe. La red tiene una longitud aproximada de 120 kilometros y esta compuesta por tuberias de diferentes diametros, ramales, interconexiones, etc. La complejidad y extension del sistema de vaporductos hace muy dificil el analisis del transporte y suministro de vapor a las plantas generadoras. Lo anterior creo la necesidad de contar con una herramienta que ayudara en el analisis del sistema con el fin de

  17. Steam explosion simulation code JASMINE v.3 user's guide

    International Nuclear Information System (INIS)

    Moriyama, Kiyofumi; Maruyama, Yu; Nakamura, Hideo

    2008-07-01

    A steam explosion occurs when hot liquid contacts with cold volatile liquid. In this phenomenon, fine fragmentation of the hot liquid causes extremely rapid heat transfer from the hot liquid to the cold volatile liquid, and explosive vaporization, bringing shock waves and destructive forces. The steam explosion due to the contact of the molten core material and coolant water during severe accidents of light water reactors has been regarded as a potential threat to the integrity of the containment vessel. We developed a mechanistic steam explosion simulation code, JASMINE, that is applicable to plant scale assessment of the steam explosion loads. This document, as a manual for users of JASMINE code, describes the models, numerical solution methods, and also some verification and example calculations, as well as practical instructions for input preparation and usage of the code. (author)

  18. Efficient steam generation by inexpensive narrow gap evaporation device for solar applications.

    Science.gov (United States)

    Morciano, Matteo; Fasano, Matteo; Salomov, Uktam; Ventola, Luigi; Chiavazzo, Eliodoro; Asinari, Pietro

    2017-09-20

    Technologies for solar steam generation with high performance can help solving critical societal issues such as water desalination or sterilization, especially in developing countries. Very recently, we have witnessed a rapidly growing interest in the scientific community proposing sunlight absorbers for direct conversion of liquid water into steam. While those solutions can possibly be of interest from the perspective of the involved novel materials, in this study we intend to demonstrate that efficient steam generation by solar source is mainly due to a combination of efficient solar absorption, capillary water feeding and narrow gap evaporation process, which can also be achieved through common materials. To this end, we report both numerical and experimental evidence that advanced nano-structured materials are not strictly necessary for performing sunlight driven water-to-vapor conversion at high efficiency (i.e. ≥85%) and relatively low optical concentration (≈10 suns). Coherently with the principles of frugal innovation, those results unveil that solar steam generation for desalination or sterilization purposes may be efficiently obtained by a clever selection and assembly of widespread and inexpensive materials.

  19. Thermomechanical Model and Bursting Tests to Evaluate the Risk of Swelling and Bursting of Modified 9Cr-1Mo Steel Steam Generator Tubes during a Sodium-Water Reaction Accident

    Directory of Open Access Journals (Sweden)

    C. Bertrand

    2014-01-01

    Full Text Available The MECTUB code was developed to evaluate the risk of swelling and bursting of Steam Generator (SG tubes. This code deals with the physic of intermediate steam-water leaks into sodium which induce a Sodium-Water Reaction (SWR. It is based on a one-dimensional calculation to describe the thermomechanical behavior of tubes under a high internal pressure and a fast external overheating. The mechanical model of MECTUB is strongly correlated with the kind of the material of the SG tubes. It has been developed and validated by using experiments performed on the alloy 800. A change to tubes made of Modified 9Cr-1Mo steel requires more knowledge of Modified 9Cr-1Mo steel behavior which influences the bursting time at high temperatures (up to 1200°C. Studies have been initiated to adapt the mechanical model and to qualify it for this material. The first part of this paper focuses on the mechanical law modelling (elasticity, plasticity, and creep for Modified 9Cr-1Mo steel and on overheating thermal data. In a second part, the results of bursting tests performed on Modified 9Cr-1Mo tubes in the SQUAT facility of CEA are used to validate the mechanical model of MECTUB for the Modified 9Cr-1Mo material.

  20. submitter Prospects of Sterile Neutrino Search with the FCC-ee

    CERN Document Server

    Bay Nielsen, Sissel

    A proposed future circular e + e − collider, the FCC-ee, is suggested to search for sterile neutrinos. The Neutrino Minimal Standard Model, νMSM, is a model of sterile neutrinos, that accommodates explanations for several phenomena of physics beyond the Standard Model. This thesis presents an overview of the theoretical motivation for νMSM, an outline of the experimental conditions at the FCC-ee, and a review of previous accelerator bounds for sterile neutrinos. Two studies of sterile neutrinos with masses at the electroweak scale are introduced, an analysis of long lived sterile neutrinos, and an analysis of short lived sterile neutrinos. Both analyses include background studies and sensitivity estimates for the FCC-ee detector. The study of long lived sterile neutrinos is based on a search for detectable displaced vertices with 1012 Z decays, obtaining a search reach on the mixing angle |θ| 2 as small as 10−11. The study of short lived sterile neutrinos is a Monte Carlo study with a cut-based analysi...