Radiosterilization and steam autoclaving sterilization effects on phosphite antioxidant stability

International Nuclear Information System (INIS)

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

1997-01-01

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. (orig.)

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.

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.

Improved Sterilization of Sensitive Biomaterials with Supercritical Carbon Dioxide at Low Temperature.

Directory of Open Access Journals (Sweden)

Anne Bernhardt

Full Text Available The development of bio-resorbable implant materials is rapidly going on. Sterilization of those materials is inevitable to assure the hygienic requirements for critical medical devices according to the medical device directive (MDD, 93/42/EG. Biopolymer-containing biomaterials are often highly sensitive towards classical sterilization procedures like steam, ethylene oxide treatment or gamma irradiation. Supercritical CO₂ (scCO₂ treatment is a promising strategy for the terminal sterilization of sensitive biomaterials at low temperature. In combination with low amounts of additives scCO₂ treatment effectively inactivates microorganisms including bacterial spores. We established a scCO₂ sterilization procedure under addition of 0.25% water, 0.15% hydrogen peroxide and 0.5% acetic anhydride. The procedure was successfully tested for the inactivation of a wide panel of microorganisms including endospores of different bacterial species, vegetative cells of gram positive and negative bacteria including mycobacteria, fungi including yeast, and bacteriophages. For robust testing of the sterilization effect with regard to later application of implant materials sterilization all microorganisms were embedded in alginate/agarose cylinders that were used as Process Challenge Devices (PCD. These PCD served as surrogate models for bioresorbable 3D scaffolds. Furthermore, the impact of scCO₂ sterilization on mechanical properties of polysaccharide-based hydrogels and collagen-based scaffolds was analyzed. The procedure was shown to be less compromising on mechanical and rheological properties compared to established low-temperature sterilization methods like gamma irradiation and ethylene oxide exposure as well as conventional steam sterilization. Cytocompatibility of alginate gels and scaffolds from mineralized collagen was compared after sterilization with ethylene oxide, gamma irradiation, steam sterilization and scCO₂ treatment. Human

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

Cleaning, disinfection and sterilization of surface prion contamination.

Science.gov (United States)

McDonnell, G; Dehen, C; Perrin, A; Thomas, V; Igel-Egalon, A; Burke, P A; Deslys, J P; Comoy, E

2013-12-01

Prion contamination is a risk during device reprocessing, being difficult to remove and inactivate. Little is known of the combined effects of cleaning, disinfection and sterilization during a typical reprocessing cycle in clinical practice. To investigate the combination of cleaning, disinfection and/or sterilization on reducing the risk of surface prion contamination. In vivo test methods were used to study the impact of cleaning alone and cleaning combined with thermal disinfection and high- or low-temperature sterilization processes. A standardized test method, based on contamination of stainless steel wires with high titres of scrapie-infected brain homogenates, was used to determine infectivity reduction. Traditional chemical methods of surface decontamination against prions were confirmed to be effective, but extended steam sterilization was more variable. Steam sterilization alone reduced the risk of prion contamination under normal or extended exposure conditions, but did show significant variation. Thermal disinfection had no impact in these studies. Cleaning with certain defined formulations in combination with steam sterilization can be an effective prion decontamination process, in particular with alkaline formulations. Low-temperature, gaseous hydrogen peroxide sterilization was also confirmed to reduce infectivity in the presence and absence of cleaning. Prion decontamination is affected by the full reprocessing cycle used on contaminated surfaces. The correct use of defined cleaning, disinfection and sterilization methods as tested in this report in the scrapie infectivity assay can provide a standard precaution against prion contamination. Copyright © 2013 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Sterilization of heparinized cuprophan hemodialysis membranes

OpenAIRE

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. Sterilization did not result in a release of heparin or heparin fragments from heparinized Cuprophan. Sterilization of heparinized Cuprophan by means of EtO exposure and gamma irradiation induced a slight, i...

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)

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)

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.

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

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

The Effect of Two Different Sterilization Methods on The Surface Topography and Microbial Contamination of Different Types of Endodontic Files

International Nuclear Information System (INIS)

Yousri, H.R.M.

2014-01-01

Sterilization is an integral part of the dental field. Sterilization should be used for instruments, surgical gloves and other items that come in direct contact with the blood stream or normally sterile tissues. Because sterilization is a process, not a single event, all components must be carried out correctly for sterilization to occur. To be effective, sterilization requires time, contact, temperature and with steam sterilization, high pressure. The effectiveness of any method of sterilization is also dependent upon four other factors: The type of microorganism present, the number of microorganisms present, the amount and type of organic material that protects the microorganisms and the number of cracks and crevices on an instrument that might harbor microorganisms. The most commonly used and standard methods of sterilization is the steam under pressure method using the autoclaves. However, it's not free from drawbacks; where it is not suitable for the heat sensitive equipment's such as the plastics, rubber. Also repeated autoclaving can cause pitting and dulling of cutting edges of instruments which might affect their clinical performance. Another alternative method of sterilization is by gamma rays which have been introduced for the sterilization of heat sensitive equipment's. Therefore conducting a study to investigate the effect of repeated sterilization cycles by either steam under pressure or gamma radiation on the surface topography of root canal enlarging instruments was thought to be valuable. The null hypothesis tested is that there is no difference in the effect of repeated sterilization by either steam under pressure or gamma radiation on the surface topography of root canal enlarging instruments

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.

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.

Production of a sterile species via active-sterile mixing: An exactly solvable model

Science.gov (United States)

Boyanovsky, D.

2007-11-01

The production of a sterile species via active-sterile mixing in a thermal medium is studied in an exactly solvable model. The exact time evolution of the sterile distribution function is determined by the dispersion relations and damping rates Γ1,2 for the quasiparticle modes. These depend on γ˜=Γaa/2ΔE, with Γaa the interaction rate of the active species in absence of mixing and ΔE the oscillation frequency in the medium without damping. γ˜≪1, γ˜≫1 describe the weak and strong damping limits, respectively. For γ˜≪1, Γ1=Γaacos⁡2θm; Γ2=Γaasin⁡2θm where θm is the mixing angle in the medium and the sterile distribution function does not obey a simple rate equation. For γ˜≫1, Γ1=Γaa and Γ2=Γaasin⁡22θm/4γ˜2, is the sterile production rate. In this regime sterile production is suppressed and the oscillation frequency vanishes at an Mikheyev-Smirnov-Wolfenstein (MSW) resonance, with a breakdown of adiabaticity. These are consequences of quantum Zeno suppression. For active neutrinos with standard model interactions the strong damping limit is only available near an MSW resonance if sin⁡2θ≪αw with θ the vacuum mixing angle. The full set of quantum kinetic equations for sterile production for arbitrary γ˜ are obtained from the quantum master equation. Cosmological resonant sterile neutrino production is quantum Zeno suppressed relieving potential uncertainties associated with the QCD phase transition.

Sterilization processes. Meeting the demands of today's health care technology.

Science.gov (United States)

Crow, S

1993-09-01

Universal Precautions dictate sterilization for all invasive equipment that break the blood barrier; however, current methods of sterilization, such as steam and ethylene oxide gas (ETO), are not compatible with many of the delicate, heat-sensitive surgical instruments used in modern health care. In addition, traditional sterilization methods are often too time consuming for practical use in the operating room. Clearly, new sterilization processes need to be developed. In this article, the criteria modern sterilization processes must meet and how some manufacturers plan to meet this challenge are discussed. In addition, the pros and cons of using peracetic acid (the newest sterilization process currently available) are examined.

Influence of different sterilization processes on the properties of commercial poly(lactic acid)

International Nuclear Information System (INIS)

Savaris, M.; Santos, V. dos; Brandalise, R.N.

2016-01-01

This study aims at analyzing the modifications in the morphological, physical, chemical and thermal properties of commercial poly(lactic acid) (PLA) films after exposure to five different sterilization processes. Films were obtained by compression molding, hygienized and sterilized by ethylene oxide (SEtO), hydrogen peroxide plasma (SH 2 O 2 ), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLA SEtO , PLA SH2O2 , PLA SEB and PLA SGR exhibited thermal and physical changes after being submitted to sterilization processes. PLA SSS showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH 2 O 2 , SEB and EGR can be applied for the sterilization of PLA films and the SSS process is not recommended in view of the data obtained and test conditions reported in this study for PLA films. - Highlights: • PLA was subjected to five different sterilization process. • All sterilization processes do not changed the hydrophilicity of PLA. • Morphological, chemical, physical and thermal changes were observed for the PLA SSS . • The sterilization by saturated steam is not recommended to sterilize PLA.

Dynamic modelling of nuclear steam generators

International Nuclear Information System (INIS)

Kerlin, T.W.; Katz, E.M.; Freels, J.; Thakkar, J.

1980-01-01

Moving boundary, nodal models with dynamic energy balances, dynamic mass balances, quasi-static momentum balances, and an equivalent single channel approach have been developed for steam generators used in nuclear power plants. The model for the U-tube recirculation type steam generator is described and comparisons are made of responses from models of different complexity; non-linear versus linear, high-order versus low order, detailed modeling of the control system versus a simple control assumption. The results of dynamic tests on nuclear power systems show that when this steam generator model is included in a system simulation there is good agreement with actual plant performance. (author)

Three-dimensional modeling of nuclear steam generator

International Nuclear Information System (INIS)

Bogdan, Z.; Afgan, N.

1985-01-01

In this paper mathematical model for steady-state simulation of thermodynamic and hydraulic behaviour of U-tube nuclear steam generator is described. The model predicts three-dimensional distribution of temperatures, pressures, steam qualities and velocities in the steam generator secondary loop. In this analysis homogeneous two phase flow model is utilized. Foe purpose of the computer implementation of the mathematical model, a special flow distribution code NUGEN was developed. Calculations are performed with the input data and geometrical characteristics related to the D-4 (westinghouse) model of U-tube nuclear steam generator built in Krsko, operating under 100% load conditions. Results are shown in diagrams giving spatial distribution of pertinent variables in the secondary loop. (author)

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

Influence of different sterilization processes on the properties of commercial poly(lactic acid)

Energy Technology Data Exchange (ETDEWEB)

Savaris, M.; Santos, V. dos, E-mail: vsantos2@ucs.br; Brandalise, R.N.

2016-12-01

This study aims at analyzing the modifications in the morphological, physical, chemical and thermal properties of commercial poly(lactic acid) (PLA) films after exposure to five different sterilization processes. Films were obtained by compression molding, hygienized and sterilized by ethylene oxide (SEtO), hydrogen peroxide plasma (SH{sub 2}O{sub 2}), saturated steam (SSS), electron beam radiation (SEB) and gamma radiation (SGR). The samples of PLA{sub SEtO}, PLA{sub SH2O2}, PLA{sub SEB} and PLA{sub SGR} exhibited thermal and physical changes after being submitted to sterilization processes. PLA{sub SSS} showed morphological, chemical, thermal and physical changes. It is concluded that processes by SEtO, SH{sub 2}O{sub 2}, SEB and EGR can be applied for the sterilization of PLA films and the SSS process is not recommended in view of the data obtained and test conditions reported in this study for PLA films. - Highlights: • PLA was subjected to five different sterilization process. • All sterilization processes do not changed the hydrophilicity of PLA. • Morphological, chemical, physical and thermal changes were observed for the PLA{sub SSS}. • The sterilization by saturated steam is not recommended to sterilize PLA.

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.

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.

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

International Nuclear Information System (INIS)

George, Karina A.; Shadforth, Audra M.A.; Chirila, Traian V.; Laurent, Matthieu J.; Stephenson, Sally-Anne; Edwards, Grant A.; Madden, Peter W.

2013-01-01

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: ► The effects of four methods of sterilization on the properties of silk fibroin films were investigated. ► Steam treatment leads to stiffer films but to lower transparency and variable surface topography. ► Degradation of fibroin is enhanced in the films that were gamma-irradiated. ► The effects on mechanical properties are explained through changes in both primary and secondary structure of fibroin. ► Gamma-irradiation and immersion in aqueous ethanol are suggested as preferred methods of sterilization.

[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.

A three-dimensional laboratory steam injection model allowing in situ saturation measurements. [Comparing steam injection and steam foam injection with nitrogen and without nitrogen

Energy Technology Data Exchange (ETDEWEB)

Demiral, B.M.R.; Pettit, P.A.; Castanier, L.M.; Brigham, W.E.

1992-08-01

The CT imaging technique together with temperature and pressure measurements were used to follow the steam propagation during steam and steam foam injection experiments in a three dimensional laboratory steam injection model. The advantages and disadvantages of different geometries were examined to find out which could best represent radial and gravity override flows and also fit the dimensions of the scanning field of the CT scanner. During experiments, steam was injected continuously at a constant rate into the water saturated model and CT scans were taken at six different cross sections of the model. Pressure and temperature data were collected with time at three different levels in the model. During steam injection experiments, the saturations obtained by CT matched well with the temperature data. That is, the steam override as observed by temperature data was also clearly seen on the CT pictures. During the runs where foam was present, the saturation distributions obtained from CT pictures showed a piston like displacement. However, the temperature distributions were different depending on the type of steam foam process used. The results clearly show that the pressure/temperature data alone are not sufficient to study steam foam in the presence of non-condensible gas.

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

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.

Parametric study for horizontal steam generator modelling

Energy Technology Data Exchange (ETDEWEB)

Ovtcharova, I [Energoproekt, Sofia (Bulgaria)

1996-12-31

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.

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.

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.

Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

International Nuclear Information System (INIS)

Liu, X.L.; Zhou, W.R.; Wu, Y.H.; Cheng, Y.; Zheng, Y.F.

2013-01-01

The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process

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.

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

Science.gov (United States)

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. PMID:24883365

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)

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.

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

Confirming Sterility of an Autoclaved Infected Femoral Component for Use in an Articulated Antibiotic Knee Spacer: A Pilot Study.

Science.gov (United States)

Lyons, Steven T; Wright, Coy A; Krute, Christina N; Rivera, Frances E; Carroll, Ronan K; Shaw, Lindsey N

2016-01-01

Antibiotic spacer designs have proven effective at eradicating infection during a two-stage revision arthroplasty. Temporary reuse of the steam-sterilized femoral component and a new all poly tibia component has been described as an effective articulating antibiotic spacer, but sterility concerns persist. Six explanted cobalt chrome femurs from patients with grossly infected TKA's and six stock femurs inoculated with different bacterial species were confirmed to be bacteria-free after autoclaving under a standard gravity-displacement cycle. The effect of steam sterilization on cobalt chrome fragments contaminated with MRSA biofilm was analyzed microscopically to quantify remaining biofilm. The autoclave significantly reduced the biofilm burden on the cobalt chrome fragments. This study confirmed sterility of the femur after a standard gravity-displacement cycle (132°C, 27 PSIG, 10 minutes). Copyright © 2016 Elsevier Inc. All rights reserved.

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...

A mathematical model of steam-drum dynamics

International Nuclear Information System (INIS)

Moeck, E.O.; Hinds, H.W.

1976-12-01

Mathematical equations describing the dynamic behaviour of pressure, water mass, etc. in a steam drum are derived from basic principles. The resultant model includes such effects as steam superheating and water subcooling as well as spontaneous flashing of liquid and condensation of vapour. Experimental data from a pressurizer are adequately predicted by the model. The pressure rise following a turbine trip can be predicted by the isentropic-compression model but not by the thermodynamic-equilibrium model. The equations are individually linearized and implemented on an analog computer in such a way that their non-linear behaviour is retained for small-perturbation studies. (author)

Performance Modelling of Steam Turbine Performance using Fuzzy ...

African Journals Online (AJOL)

Performance Modelling of Steam Turbine Performance using Fuzzy Logic ... AFRICAN JOURNALS ONLINE (AJOL) · Journals · Advanced Search · USING AJOL · RESOURCES. Journal of Applied Sciences and Environmental Management ... A Fuzzy Inference System for predicting the performance of steam turbine

Mirror model for sterile neutrinos

International Nuclear Information System (INIS)

Berezinsky, Veniamin; Narayan, Mohan; Vissani, Francesco

2003-01-01

Sterile neutrinos are studied as subdominant contribution to solar neutrino physics. The mirror-matter neutrinos are considered as sterile neutrinos. We use the symmetric mirror model with gravitational communication between mirror and visible sectors. This communication term provides mixing between visible and mirror neutrinos with the basic scale μ=v EW 2 /M Pl =2.5x10 -6 eV, where v EW =174 GeV is the vacuum expectation value of the standard electroweak group and M Pl is the Planckian mass. It is demonstrated that each mass eigenstate of active neutrinos splits into two states separated by small Δm 2 . Unsuppressed oscillations between active and sterile neutrinos (ν a ↔ν s ) occur only in transitions between each of these close pairs ('windows'). These oscillations are characterized by very small Δm 2 and can suppress the flux and distort spectrum of pp-neutrinos in detectable way. The other observable effect is anomalous seasonal variation of neutrino flux, which appears in LMA solution. The considered subdominant neutrino oscillations ν a ↔ν s can reveal itself as big effects in observations of supernova neutrinos and high-energy (HE) neutrinos. In the case of HE neutrinos they can provide a very large diffuse flux of active neutrinos unconstrained by the e-m cascade upper limit

Development and validation of a CFD-based steam reformer model

DEFF Research Database (Denmark)

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

2006-01-01

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...... for expensive prototypes. This paper presents an advanced Computational Fluid Dynamics based model of a steam reformer. The model was implemented in the commercial CFD code Fluent through the User Defined Functions interface. The model accounts for the flue gas flow as well as the reformate flow including...... 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...

A three-dimensional laboratory steam injection model allowing in situ saturation measurements

Energy Technology Data Exchange (ETDEWEB)

Demiral, B.M.R.; Pettit, P.A.; Castanier, L.M.; Brigham, W.E.

1992-08-01

The CT imaging technique together with temperature and pressure measurements were used to follow the steam propagation during steam and steam foam injection experiments in a three dimensional laboratory steam injection model. The advantages and disadvantages of different geometries were examined to find out which could best represent radial and gravity override flows and also fit the dimensions of the scanning field of the CT scanner. During experiments, steam was injected continuously at a constant rate into the water saturated model and CT scans were taken at six different cross sections of the model. Pressure and temperature data were collected with time at three different levels in the model. During steam injection experiments, the saturations obtained by CT matched well with the temperature data. That is, the steam override as observed by temperature data was also clearly seen on the CT pictures. During the runs where foam was present, the saturation distributions obtained from CT pictures showed a piston like displacement. However, the temperature distributions were different depending on the type of steam foam process used. The results clearly show that the pressure/temperature data alone are not sufficient to study steam foam in the presence of non-condensible gas.

Model studies of the vertical steam generator thermal-hydraulic characteristics

International Nuclear Information System (INIS)

Desyatun, V.F.; Moskvichev, V.F.; Ulasov, V.M.; Morozov, V.G.; Burkov, V.K.; Grebennikov, V.N.

1984-01-01

Results of investigations conducted to clarify the calculation technique and to test the workability of the main elements and units of the PGV-250 vertical steam generator of saturated steam are considered. The steam generating capacity of the plant is 1486 t/h, thermal power is 792 MW. Steam generation follows a multiple circulation scheme. The heat surface comprises 330-shields. The investigations are carried out with a model which reproduces all the main elements of the steam generator xcluding the economizer section. The flow rates of feed water, generated steam and coolant of the first circuit as well as temperature, pressure and humidity of the generated steam past the separator are determined. The average heat transfer factors of the heat surface are calculated on the base of the data obtained and a conclusion is drawn on the correctness of the thermohydraulic calculation technique used in development of the PGV-250 steam generator design. Temperature pulsations and heat surface steaming are not observed. The steam humidity at the outlet and steam capture into sinking tubes are within permissible values

Mathematical models for the use of sterile insects

International Nuclear Information System (INIS)

Barclay, H.J.

2005-01-01

This chapter begins with a consideration of simple population models. The sterility formulation proposed by Knipling is then included into the population models, and these are elaborated in systematic fashion to include the major biological factors that will affect the success of the sterile insect technique (SIT) control programme. These factors include residual fertility, differential competitive ability of wild and sterilized males, mating patterns, immigration, and various combinations of these features. Also examined are density-dependence, age structure, population aggregation, biotic interactions with other species, and then integration of the SIT with other control methods. It was found that combinations of factors are synergistic: combinations of detrimental factors such as residual fertility and inferior competitive ability put severe limits on the probable success of the control programme, while combinations of control methods are much more likely to succeed than single control methods. This is because each control method needs only to account for a smaller proportion of the total mortality when combined with other methods than when acting alone. (author)

Two-fluid model with droplet size distribution for condensing steam flows

International Nuclear Information System (INIS)

Wróblewski, Włodzimierz; Dykas, Sławomir

2016-01-01

The process of energy conversion in the low pressure part of steam turbines may be improved using new and more accurate numerical models. The paper presents a description of a model intended for the condensing steam flow modelling. The model uses a standard condensation model. A physical and a numerical model of the mono- and polydispersed wet-steam flow are presented. The proposed two-fluid model solves separate flow governing equations for the compressible, inviscid vapour and liquid phase. The method of moments with a prescribed function is used for the reconstruction of the water droplet size distribution. The described model is presented for the liquid phase evolution in the flow through the de Laval nozzle. - Highlights: • Computational Fluid Dynamics. • Steam condensation in transonic flows through the Laval nozzles. • In-house CFD code – two-phase flow, two-fluid monodispersed and polydispersed model.

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.

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.

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.

2013-01-01

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. PMID:23836642

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.

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)

1996-12-31

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.

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. .

A model predictive controller for the water level of nuclear steam generators

International Nuclear Information System (INIS)

Na, Man Gyun

2001-01-01

In this work, the model predictive control method was applied to a linear model and a nonlinear model of steam generators. The parameters of a linear model for steam generators are very different according to the power levels. The model predictive controller was designed for the linear steam generator model at a fixed power level. The proposed controller designed at the fixed power level showed good performance for any other power levels by changing only the input-weighting factor. As the input-weighting factor usually increases, its relative stability does so. The stem generator has some nonlinear characteristics. Therefore, the proposed algorithm has been implemented for a nonlinear model of the nuclear steam generator to verify its real performance and also, showed good performance. (author)

Testing sterile neutrino extensions of the Standard Model at future lepton colliders

Science.gov (United States)

Antusch, Stefan; Fischer, Oliver

2015-05-01

Extending the Standard Model (SM) with sterile ("right-handed") neutrinos is one of the best motivated ways to account for the observed neutrino masses. We discuss the expected sensitivity of future lepton collider experiments for probing such extensions. An interesting testable scenario is given by "symmetry protected seesaw models", which theoretically allow for sterile neutrino masses around the electroweak scale with up to order one mixings with the light (SM) neutrinos. In addition to indirect tests, e.g. via electroweak precision observables, sterile neutrinos with masses around the electroweak scale can also be probed by direct searches, e.g. via sterile neutrino decays at the Z pole, deviations from the SM cross section for four lepton final states at and beyond the WW threshold and via Higgs boson decays. We study the present bounds on sterile neutrino properties from LEP and LHC as well as the expected sensitivities of possible future lepton colliders such as ILC, CEPC and FCC-ee (TLEP).

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.

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...

The Evaluation of Steam Generator Level Measurement Model for OPR1000 Using RETRAN-3D

International Nuclear Information System (INIS)

Doo Yong Lee; Soon Joon Hong; Byung Chul Lee; Heok Soon Lim

2006-01-01

Steam generator level measurement is important factor for plant transient analyses using best estimate thermal hydraulic computer codes since the value of steam generator level is used for steam generator level control system and plant protection system. Because steam generator is in the saturation condition which includes steam and liquid together and is the place that heat exchange occurs from primary side to secondary side, computer codes are hard to calculate steam generator level realistically without appropriate level measurement model. In this paper, we prepare the steam generator models using RETRAN-3D that include geometry models, full range feedwater control system and five types of steam generator level measurement model. Five types of steam generator level measurement model consist of level measurement model using elevation difference in downcomer, 1D level measurement model using fluid mass, 1D level measurement model using fluid volume, 2D level measurement model using power and fluid mass, and 2D level measurement model using power and fluid volume. And we perform the evaluation of the capability of each steam generator level measurement model by simulating the real plant transient condition, the title is 'Reactor Trip by The Failure of The Deaerator Level Control Card of Ulchin Unit 3'. The comparison results between real plant data and RETRAN-3D analyses for each steam generator level measurement model show that 2D level measurement model using power and fluid mass or fluid volume has more realistic prediction capability compared with other level measurement models. (authors)

Linear Dynamics Model for Steam Cooled Fast Power Reactors

Energy Technology Data Exchange (ETDEWEB)

Vollmer, H

1968-04-15

A linear analytical dynamic model is developed for steam cooled fast power reactors. All main components of such a plant are investigated on a general though relatively simple basis. The model is distributed in those parts concerning the core but lumped as to the external plant components. Coolant is considered as compressible and treated by the actual steam law. Combined use of analogue and digital computer seems most attractive.

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

[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

Econometric simulation model of the US market for steam coal

Energy Technology Data Exchange (ETDEWEB)

Labys, W C; Paik, S; Liebenthal, A M

1979-01-01

An econometric investigation of the historical structure of the U.S. market for steam coal was made to forecast demand, supply, inventory, and price behavior. The structure of the steam coal market is examined and a corresponding theoretical model developed. Consideration is given to alternative simulation models based on various combinations of hypotheses about demand and supply. Results from the models are presented and interpreted. 19 references.

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.

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.

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

Steam generator and circulator model for the HELAP code

International Nuclear Information System (INIS)

Ludewig, H.

1975-07-01

An outline is presented of the work carried out in the 1974 fiscal year on the GCFBR safety research project consisting of the development of improved steam generator and circulator (steam turbine driven helium compressor) models which will eventually be inserted in the HELAP (1) code. Furthermore, a code was developed which will be used to generate steady state input for the primary and secondary sides of the steam generator. The following conclusions and suggestions for further work are made: (1) The steam-generator and circulator model are consistent with the volume and junction layout used in HELAP, (2) with minor changes these models, when incorporated in HELAP, could be used to simulate a direct cycle plant, (3) an explicit control valve model is still to be developed and would be very desirable to control the flow to the turbine during a transient (initially this flow will be controlled by using the existing check valve model); (4) the friction factor in the laminar flow region is computed inaccurately, this might cause significant errors in loss-of-flow accidents; and (5) it is felt that HELAP will still use a large amount of computer time and will thus be limited to design basis accidents without scram or loss of flow transients with and without scram. Finally it may also be used as a test bed for the development of prototype component models which would be incorporated in a more sophisticated system code, developed specifically for GCFBR's

Steam generators clogging diagnosis through physical and statistical modelling

International Nuclear Information System (INIS)

Girard, S.

2012-01-01

Steam generators are massive heat exchangers feeding the turbines of pressurised water nuclear power plants. Internal parts of steam generators foul up with iron oxides which gradually close some holes aimed for the passing of the fluid. This phenomenon called clogging causes safety issues and means to assess it are needed to optimise the maintenance strategy. The approach investigated in this thesis is the analysis of steam generators dynamic behaviour during power transients with a mono dimensional physical model. Two improvements to the model have been implemented. One was taking into account flows orthogonal to the modelling axis, the other was introducing a slip between phases accounting for velocity difference between liquid water and steam. These two elements increased the model's degrees of freedom and improved the adequacy of the simulation to plant data. A new calibration and validation methodology has been proposed to assess the robustness of the model. The initial inverse problem was ill posed: different clogging spatial configurations can produce identical responses. The relative importance of clogging, depending on its localisation, has been estimated by sensitivity analysis with the Sobol' method. The dimension of the model functional output had been previously reduced by principal components analysis. Finally, the input dimension has been reduced by a technique called sliced inverse regression. Based on this new framework, a new diagnosis methodology, more robust and better understood than the existing one, has been proposed. (author)

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.

Pest persistence and eradication conditions in a deterministic model for sterile insect release.

Science.gov (United States)

Gordillo, Luis F

2015-01-01

The release of sterile insects is an environment friendly pest control method used in integrated pest management programmes. Difference or differential equations based on Knipling's model often provide satisfactory qualitative descriptions of pest populations subject to sterile release at relatively high densities with large mating encounter rates, but fail otherwise. In this paper, I derive and explore numerically deterministic population models that include sterile release together with scarce mating encounters in the particular case of species with long lifespan and multiple matings. The differential equations account separately the effects of mating failure due to sterile male release and the frequency of mating encounters. When insects spatial spread is incorporated through diffusion terms, computations reveal the possibility of steady pest persistence in finite size patches. In the presence of density dependence regulation, it is observed that sterile release might contribute to induce sudden suppression of the pest population.

Treatment of clinical solid waste using a steam autoclave as a possible alternative technology to incineration.

Science.gov (United States)

Hossain, Md Sohrab; Balakrishnan, Venugopal; Rahman, Nik Norulaini Nik Ab; Sarker, Md Zaidul Islam; Kadir, Mohd Omar Ab

2012-03-01

A steam autoclave was used to sterilize bacteria in clinical solid waste in order to determine an alternative to incineration technology in clinical solid waste management. The influence of contact time (0, 5, 15, 30 and 60 min) and temperature (111 °C, 121 °C and 131 °C) at automated saturated steam pressure was investigated. Results showed that with increasing contact time and temperature, the number of surviving bacteria decreased. The optimum experimental conditions as measured by degree of inactivation of bacteria were 121 °C for 15 minutes (min) for Gram negative bacteria, 121 °C and 131 °C for 60 and 30 min for Gram positive bacteria, respectively. The re-growth of bacteria in sterilized waste was also evaluated in the present study. It was found that bacterial re-growth started two days after the inactivation. The present study recommends that the steam autoclave cannot be considered as an alternative technology to incineration in clinical solid waste management.

Treatment of Clinical Solid Waste Using a Steam Autoclave as a Possible Alternative Technology to Incineration

Science.gov (United States)

Hossain, Md. Sohrab; Balakrishnan, Venugopal; Rahman, Nik Norulaini Nik Ab; Sarker, Md. Zaidul Islam; Kadir, Mohd Omar Ab

2012-01-01

A steam autoclave was used to sterilize bacteria in clinical solid waste in order to determine an alternative to incineration technology in clinical solid waste management. The influence of contact time (0, 5, 15, 30 and 60 min) and temperature (111 °C, 121 °C and 131 °C) at automated saturated steam pressure was investigated. Results showed that with increasing contact time and temperature, the number of surviving bacteria decreased. The optimum experimental conditions as measured by degree of inactivation of bacteria were 121 °C for 15 minutes (min) for Gram negative bacteria, 121 °C and 131 °C for 60 and 30 min for Gram positive bacteria, respectively. The re-growth of bacteria in sterilized waste was also evaluated in the present study. It was found that bacterial re-growth started two days after the inactivation. The present study recommends that the steam autoclave cannot be considered as an alternative technology to incineration in clinical solid waste management. PMID:22690168

Parametrization of Seesaw Models and Light Sterile Neutrinos

CERN Document Server

Blennow, Mattias

2011-01-01

The recent recomputation of the neutrino fluxes from nuclear reactors relaxes the tension between the LSND and MiniBooNE anomalies and disappearance data when interpreted in terms of sterile neutrino oscillations. The simplest extension of the Standard Model with such fermion singlets is the addition of right-handed sterile neutrinos with small Majorana masses. Even when introducing three right-handed neutrinos, this scenario has less free parameters than the 3+2 scenarios studied in the literature. This begs the question whether the best fit regions obtained can be reproduced by this simplest extension of the Standard Model. In order to address this question, we devise an exact parametrization of Standard Model extensions with right-handed neutrinos. Apart from the usual 3x3 neutrino mixing matrix and the 3 masses of the lightest neutrinos, the extra degrees of freedom are encoded in another 3x3 unitary matrix and 3 additional mixing angles. The parametrization includes all the correlations among masses and ...

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)

Support vector regression model based predictive control of water level of U-tube steam generators

Energy Technology Data Exchange (ETDEWEB)

Kavaklioglu, Kadir, E-mail: kadir.kavaklioglu@pau.edu.tr

2014-10-15

Highlights: • Water level of U-tube steam generators was controlled in a model predictive fashion. • Models for steam generator water level were built using support vector regression. • Cost function minimization for future optimal controls was performed by using the steepest descent method. • The results indicated the feasibility of the proposed method. - Abstract: A predictive control algorithm using support vector regression based models was proposed for controlling the water level of U-tube steam generators of pressurized water reactors. Steam generator data were obtained using a transfer function model of U-tube steam generators. Support vector regression based models were built using a time series type model structure for five different operating powers. Feedwater flow controls were calculated by minimizing a cost function that includes the level error, the feedwater change and the mismatch between feedwater and steam flow rates. Proposed algorithm was applied for a scenario consisting of a level setpoint change and a steam flow disturbance. The results showed that steam generator level can be controlled at all powers effectively by the proposed method.

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

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.

Five-component propagation model for steam explosion analysis

International Nuclear Information System (INIS)

Yang, Y.; Moriyama, Kiyofumi; Park, H.S.; Maruyama, Yu; Sugimoto, Jun

1999-01-01

A five-field simulation code JASMINE-pro has been developed at JAERI for the calculation of the propagation and explosion phase of steam explosions. The basic equations and the constitutive relationships specifically utilized in the propagation models in the code are introduced in this paper. Some calculations simulating the KROTOS 1D and 2D steam explosion experiments are also stated in the paper to show the present capability of the code. (author)

Phenomenological study of extended seesaw model for light sterile neutrino

International Nuclear Information System (INIS)

Nath, Newton; Ghosh, Monojit; Goswami, Srubabati; Gupta, Shivani

2017-01-01

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 ν , depends on the Dirac neutrino mass matrix (M D ), Majorana neutrino mass matrix (M R ) and the mass matrix (M 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 D and observe that maximum five zeros in M D can lead to viable zero textures in m ν . For this study we consider four different forms for M R (one diagonal and three off diagonal) and two different forms of (M S ) containing one zero. Remarkably we obtain only two allowed forms of m ν (m eτ =0 and m ττ =0) having inverted hierarchical mass spectrum. We re-analyze the phenomenological implications of these two allowed textures of m 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 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 8 ×Z 2 .

Effects of Sterilization Cycles on PEEK for Medical Device Application

Science.gov (United States)

Yap, Wai Teng; Foo, Soo Leong; Lee, Teck Kheng

2018-01-01

The effects of the sterilization process have been studied on medical grade thermoplastic polyetheretherketone (PEEK). For a reusable medical device, material reliability is an important parameter to decide its lifetime, as it will be subjected to the continuous steam sterilization process. A spring nature, clip component was selected out of a newly designed medical device (patented) to perform this reliability study. This clip component was sterilized for a predetermined number of cycles (2, 4, 6, 8, 10, 20…100) at 121 °C for 30 min. A significant decrease of ~20% in the compression force of the spring was observed after 30 cycles, and a ~6% decrease in the lateral dimension of the clip was observed after 50 cycles. No further significant change in the compression force or dimension was observed for the subsequent sterilization cycles. Vickers hardness and differential scanning calorimetry (DSC) techniques were used to characterize the effects of sterilization. DSC results exhibited no significant change in the degree of cure and melting behavior of PEEK before and after the sterilization. Hardness measurement exhibited an increase of ~49% in hardness after just 20 cycles. When an unsterilized sample was heated for repetitive cycles without the presence of moisture (121 °C, 10 and 20 cycles), only ~7% of the maximum change in hardness was observed. PMID:29466289

Effects of Sterilization Cycles on PEEK for Medical Device Application.

Science.gov (United States)

Kumar, Amit; Yap, Wai Teng; Foo, Soo Leong; Lee, Teck Kheng

2018-02-21

The effects of the sterilization process have been studied on medical grade thermoplastic polyetheretherketone (PEEK). For a reusable medical device, material reliability is an important parameter to decide its lifetime, as it will be subjected to the continuous steam sterilization process. A spring nature, clip component was selected out of a newly designed medical device (patented) to perform this reliability study. This clip component was sterilized for a predetermined number of cycles (2, 4, 6, 8, 10, 20…100) at 121 °C for 30 min. A significant decrease of ~20% in the compression force of the spring was observed after 30 cycles, and a ~6% decrease in the lateral dimension of the clip was observed after 50 cycles. No further significant change in the compression force or dimension was observed for the subsequent sterilization cycles. Vickers hardness and differential scanning calorimetry (DSC) techniques were used to characterize the effects of sterilization. DSC results exhibited no significant change in the degree of cure and melting behavior of PEEK before and after the sterilization. Hardness measurement exhibited an increase of ~49% in hardness after just 20 cycles. When an unsterilized sample was heated for repetitive cycles without the presence of moisture (121 °C, 10 and 20 cycles), only ~7% of the maximum change in hardness was observed.

Mechanisms Underlying Mammalian Hybrid Sterility in Two Feline Interspecies Models.

Science.gov (United States)

Davis, Brian W; Seabury, Christopher M; Brashear, Wesley A; Li, Gang; Roelke-Parker, Melody; Murphy, William J

2015-10-01

The phenomenon of male sterility in interspecies hybrids has been observed for over a century, however, few genes influencing this recurrent phenotype have been identified. Genetic investigations have been primarily limited to a small number of model organisms, thus limiting our understanding of the underlying molecular basis of this well-documented "rule of speciation." We utilized two interspecies hybrid cat breeds in a genome-wide association study employing the Illumina 63 K single-nucleotide polymorphism array. Collectively, we identified eight autosomal genes/gene regions underlying associations with hybrid male sterility (HMS) involved in the function of the blood-testis barrier, gamete structural development, and transcriptional regulation. We also identified several candidate hybrid sterility regions on the X chromosome, with most residing in close proximity to complex duplicated regions. Differential gene expression analyses revealed significant chromosome-wide upregulation of X chromosome transcripts in testes of sterile hybrids, which were enriched for genes involved in chromatin regulation of gene expression. Our expression results parallel those reported in Mus hybrids, supporting the "Large X-Effect" in mammalian HMS and the potential epigenetic basis for this phenomenon. These results support the value of the interspecies feline model as a powerful tool for comparison to rodent models of HMS, demonstrating unique aspects and potential commonalities that underpin mammalian reproductive isolation. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Production-log base model for carbonate permeability distribution and steam flood optimization

Energy Technology Data Exchange (ETDEWEB)

Ahamed, S.F.; Choudhry, M.A.; Abdulbaqi, J.B. [Kuwait Gulf Oil Co. (Kuwait)

2008-10-15

This paper presented a model for the effective management of primary and thermal oil recovery operations in the Wafra Field in Kuwait, where a small huff and puff project was carried out in 1998 to determine if steam injection was a feasible recovery option for the field. The Eocene heavy oil reservoirs of the Wafra Field are carbonate rock admixtures with gypsum and anhydrite. They are the shallowest of the field's productive horizons and exhibit a high degree of fluid flow heterogeneity. The assessment of vertical and lateral permeability variation is a key factor for success of the reservoir development plan. Steam injection began in 2006 in a small scale test (SST) to determine if the innovative technology could produce steam from effluent water and to test the viability of steam injection in carbonate reservoirs. Following the success of the SST, a large scale pilot (LSP) is schedule to start in 2009. It can be used for completion strategies of injectors and producers in steam injection. The model showed that the productivity of the Eocene wells could be correlated with common available logs to develop a log based-permeability model. A series of cross plots for the perforated intervals of high and low productivity wells were constructed to develop a relationship between well productivity and location of log parameters on the plots. A relationship between rock quality, productivity and conventional log parameters was established. It was concluded that the vertical permeability and interwell continuity in the Eocene wells can be used to optimize new well placement for horizontal and vertical infill drilling. The model is also an effective tool to predict the steam injectivity profile to understand the anomalies related to temperature-depth distribution. The model can be used to improve the efficiency of formation heating by optimizing the steam flood process and steam pattern well completion. 16 refs.

Learning control for batch thermal sterilization of canned foods.

Science.gov (United States)

Syafiie, S; Tadeo, F; Villafin, M; Alonso, A A

2011-01-01

A control technique based on Reinforcement Learning is proposed for the thermal sterilization of canned foods. The proposed controller has the objective of ensuring a given degree of sterilization during Heating (by providing a minimum temperature inside the cans during a given time) and then a smooth Cooling, avoiding sudden pressure variations. For this, three automatic control valves are manipulated by the controller: a valve that regulates the admission of steam during Heating, and a valve that regulate the admission of air, together with a bleeder valve, during Cooling. As dynamical models of this kind of processes are too complex and involve many uncertainties, controllers based on learning are proposed. Thus, based on the control objectives and the constraints on input and output variables, the proposed controllers learn the most adequate control actions by looking up a certain matrix that contains the state-action mapping, starting from a preselected state-action space. This state-action matrix is constantly updated based on the performance obtained with the applied control actions. Experimental results at laboratory scale show the advantages of the proposed technique for this kind of processes. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

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.

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)

1996-12-31

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.

Thermal sterilization of heat-sensitive products using high-temperature short-time sterilization.

Science.gov (United States)

Mann, A; Kiefer, M; Leuenberger, H

2001-03-01

High-temperature short-time (HTST) sterilization with a continuous-flow sterilizer, developed for this study, was evaluated. The evaluation was performed with respect to (a) the chemical degradation of two heat-sensitive drugs in HTST range (140-160 degrees C) and (b) the microbiological effect of HTST sterilization. Degradation kinetics of two heat-sensitive drugs showed that a high peak temperature sterilization process resulted in less chemical degradation for the same microbiological effect than a low peak temperature process. Both drugs investigated could be sterilized with acceptable degradation at HTST conditions. For the evaluation of the microbiological effect, Bacillus stearothermophilus ATCC 7953 spores were used as indicator bacteria. Indicator spore kinetics (D(T), z value, k, and E(a)), were determined in the HTST range. A comparison between the Bigelow model (z value concept) and the Arrhenius model, used to describe the temperature coefficient of the microbial inactivation, demonstrated that the Bigelow model is more accurate in prediction of D(T) values in the HTST range. The temperature coefficient decreased with increasing temperature. The influence of Ca(2+) ions and pH value on the heat resistance of the indicator spores, which is known under typical sterilization conditions, did not change under HTST conditions.

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)

Peracetic Acid: A Practical Agent for Sterilizing Heat-Labile Polymeric Tissue-Engineering Scaffolds

Science.gov (United States)

Yoganarasimha, Suyog; Trahan, William R.; Best, Al M.; Bowlin, Gary L.; Kitten, Todd O.; Moon, Peter C.

2014-01-01

Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000 ppm or above sterilized electrospun scaffolds in 15 min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000 ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering. PMID:24341350

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)

Response of the steam generator VVER 1000 to a steam line break

International Nuclear Information System (INIS)

Novotny, J.; Novotny, J. Jr.

2003-01-01

Dynamic effects of a steam line break in the weld of the steam pipe and the steam collector on the steam generator system are analyzed. Modelling of a steam line break may concern two cases. The steam line without a restraint and the steam line protected by a whip restraint with viscous elements applied at the postulated break cross-section. The second case is considered. Programme SYSTUS offers a special element the stiffness and viscous damping coefficients of which may be defined as dependent on the relative displacement and velocity of its nodes respectively. A circumferential crack is simulated by a sudden decrease of longitudinal and lateral stiffness coefficients of these special SYSTUS elements to zero. The computation has shown that one can simulate the pipe to behave like completely broken during a time interval of 0,0001 s or less. These elements are used to model the whip restraint with viscous elements and viscous dampers of the GERB type as well. In the case of a whip restraint model the stiffness coefficient-displacement relation and damping coefficient - velocity relation are chosen to fit the given characteristics of the restraint. The special SYSTUS elements are used to constitute Maxwell elements modelling the elasto-plastic and viscous properties of the GERB dampers applied to the steam generator. It has been ascertained that a steam line break at the postulated weld crack between the steam pipe and the steam generator collector cannot endanger the integrity of the system even in a case of the absence of a whip restraint effect. (author)

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

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}.

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.

Fretting wear damage of steam generator tubes and its prediction modeling

International Nuclear Information System (INIS)

Che Honglong; Lei Mingkai

2013-01-01

The steam generator is the key equipment used for the energy transition in nuclear power plant. Since the high-temperature and high-pressure fluid flows with high speed, the steam generator tubes will be excited and vibrate, leading to the tremendous fretting wear problem on the tubes, sometimes even leading to tube cracking. This paper introduces typical fretting wear cases, the result of corresponding simulation wear experiment and damage mechanism which combining mechanical wear and erosion-corrosion. Work rate model could give a reasonable life prediction about the steam generator tube, and this predictive model has been used in nuclear power plant safety assessment. (authors)

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

Removal of semivolatiles from soils by steam stripping. 1. A local equilibrium model

International Nuclear Information System (INIS)

Wilson, D.J.; Clarke, A.N.

1992-01-01

A mathematical model for the in-situ steam stripping of volatile and semivolatile organics from contaminated vadose zone soils at hazardous waste sites is developed. A single steam injection well is modeled. The model assumes that the pneumatic permeability of the soil is spatially constant and isotropic, that the adsorption isotherm of the contaminant is linear, and that the local equilibrium approximation is adequate. The model is used to explore the streamlines and transit times of the injected steam as well as the effects of injection well depth and contaminant distribution on the time required for remediation

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

Science.gov (United States)

Mao, Jialin; Pfeifer, Samantha; Schlegel, Peter

2015-01-01

Objective To compare the safety and efficacy of hysteroscopic sterilization with the “Essure” device with laparoscopic sterilization in a large, all-inclusive, state cohort. Design Population based cohort study. Settings Outpatient interventional setting in New York State. Participants Women undergoing interval sterilization procedure, including hysteroscopic sterilization with Essure device and laparoscopic surgery, between 2005 and 2013. Main outcomes measures 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. Results 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%, P<0.01), major abdominal surgery (9.4% v 7.9%, P<0.01), and cesarean section (23.2% v 15.4%, P<0.01). At one year after surgery, hysteroscopic sterilization 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. Conclusions 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

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.)

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)

The effect of steam separataor efficiency on transient following a steam line break

International Nuclear Information System (INIS)

Choi, J.H.; Ohn, M.Y.; Lee, N.H.; Hwang, S.T.; Lee, S.K.

1996-01-01

Detailed thermalhydraulic simulations for CANDU 6 steam line break inside containment are performed to predict the response of the primary and secondary circuits. The analysis is performed using the thermalhydraulic computer code, CATHENA, with a coupled primary and secondary circuit model. A two-loop representation of the primary and secondary circuits is modelled. The secondary circuit model includes the feedwater line from the deaerator storage tank, multi-node steam generators and the steam line up to the turbine. Two cases were carried out using different assumptions for the efficiency of the steam separators. Case 1 assumes the efficiency of the steam separators becomes zero when the water level in the steam drum increases to the elevation of primary cyclones, or the outlet flow from the steam generator becomes higher than 150 % of normal flow. Case 2 assumes the efficiency becomes zero only when the water level in the steam drum reaches the elevation of primary cyclones. The simulation results show that system responses are sensitive to the assumption for the efficiency of the steam separators and case 1 gives higher discharge energy. Fuel cooling is assured, since primary circuit is cooled down sufficiently by the steam generators for both cases. (author)

Sterile Neutrinos, Dark Matter, and Pulsar Velocities in Models with a Higgs Singlet

International Nuclear Information System (INIS)

Kusenko, Alexander

2006-01-01

We identify the range of parameters for which the sterile neutrinos can simultaneously explain the cosmological dark matter and the observed velocities of pulsars. To satisfy all cosmological bounds, the relic sterile neutrinos must be produced sufficiently cold. This is possible in a class of models with a gauge-singlet Higgs boson coupled to the neutrinos. Sterile dark matter can be detected by the x-ray telescopes. The presence of the singlet in the Higgs sector can be tested at the CERN Large Hadron Collider

Seabrook simulator model upgrade: Implementation and validation of two-phase, nonequilibrium RCS and steam generator models

International Nuclear Information System (INIS)

Kao, S.

1990-01-01

A number of deficiencies in the original RCS and steam generator models on the Seabrook simulator were found to give unrealistic results under some off-normal and accident conditions. These deficiencies are attributed to the simplistic assumptions used in the original models, such as the homogeneous, equilibrium equations used in the pressurizer and steam generator models, and the single-phase flow model used in the RCS thermal-hydraulic model. To improve the fidelity of the simulator, efforts have been made to upgrade the RCS and steam generator models to include two-phase, nonequilibrium features. In the new RCS model, the following major assumptions are used to derive the finite difference form of the conservation equations: a donor-cell differencing scheme is adopted to allow flow reversal; a single pressure is used to evaluate properties; a single mass flow rate is assumed in each loop; enthalpy is assumed to vary linearly within each control volume; a homogeneous flow is assumed under two-phase conditions. The pressurizer is divided into a vapor region and a liquid region, each of which is represented by a set of mass and energy conservation equations. Interfacial mass and energy exchange mechanisms (condensation and flashing), thermal interactions between the vessel and fluids, and thermal nonequilibrium between the phases are included in the pressurizer model. The steam generator is divided into the vapor dome, riser, and downcomer regions. The assumptions applied are similar to those of the RCS and pressurizer models. A momentum model is incorporated to calculate the recirculation flow and simulate the downcomer level shrink/swell phenomenon. The new RCS and steam generator models are validated by comparing the simulator calculations against sister plant data and FSAR vendor analysis. The results show the new models give realistic and reliable calculations under off-normal and accident conditions

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.

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

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.

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

Dynamic model of YGN 3 and 4 steam generators for natural circulation mode

International Nuclear Information System (INIS)

Sohn, Jong Joo

1995-02-01

A dynamic model for the secondary side of Yonggwang nuclear power plant units 3 and 4 (YGN 3 and 4) steam generator model is developed to improve the accuracy of the present performance analysis code. The new model is based on the one-dimensional three region model to predict the local quality and void fraction distribution along the U-tube length. The local quality concept is used instead of the Wilson bubble rise correlation to simulate the steam generators in the natural circulation mode. The new model can be applicable to the plants in the power operation modes such as load maneuvering transients in which the steam generator internal flow is maintained in the natural circulation mode. To validate the new model, the code predictions are compared with the actual plant data measured for the selected load maneuvering tests performed during the YGN units 3 power ascension test period. The results from the improved model show better agreement with the plant data than those from the present code. Especially, the new model's capability of accurately simulating the steam generator water level behavior during the fast transients such as a large load rejection event is demonstrated

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

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.

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

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

Science.gov (United States)

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

2017-12-01

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 EGMS lines tested here, it was not clear if one or more recessive gene(s) were causing male sterility. This was tested by studying sterility segregation of the F2 populations. Daylength (photoperiod) and minimum temperatures during the period from panicle initiation to flowering had significant effects on male sterility. Results clearly showed that only one recessive gene was involved in causing male sterility. The model was applied to determine the set of sowing dates of two different EGMS lines such that both would flower at the same time the pollen would be completely sterile. In the same time the local popular variety (Sahel 108, the male pollen donor) being sufficiently fertile to produce the hybrid seeds. The model was applied to investigate the viability of the two line breeding system in the same location with climate change (+2oC) and in two other potential locations: in M'Be in Ivory Coast and in the Nile delta in Egypt. Apart from giving new insights in the relation between environment and EGMS, this study shows that these insights can be used to assess safe sowing windows and assess the suitability of sterility and fertility period of different environments for a two line hybrid rice production system.

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.

Penggunaan Analisis Regresi Linear Berganda untuk Mendapatkan Model Prediksi Respon Asam Lemak Bebas dan Dobi Hasil Rebusan Tandan Buah Segar Sawit

Directory of Open Access Journals (Sweden)

Pandu Imam

2017-10-01

Full Text Available Target of this research are : ( 1 Knowing physical result of steaming of Fresh Fruit Bunch; ( 2 Knowing the chemical of result of steaming of Fresh Fruit Bunch; ( 3 Finding model of prediction respon result of sterilization of Fresh Fruit Bunch ( 4 Determining time depth of steaming most precise to condition of raw material ( FFB to be sterilization. This research done at PT.Bio Nusantara Teknologi Bengkulu, by using horizontal type sterilizer. Research method the used  experiment which is  direct to be done at factory.  Multiple regression analysis to analyse data obtained, to the investigation of influence of free variable to variable of respon representing indicator efficacy of sterilization operation. Result of research indicate that treatment of variation : heavy classification of bunches,  fruit maturity and time depth steaming to have an effect on to respon result of sterilization perceived. Model of Prediction of met steaming respon as follows : Y1(Evaporation % = 5,18 - 0,042 X1- 0,012 X2+0,082 X3 ; Y2 ( Fruit lose, g=1629,96+8,14X1 - 3,22 X2 - 10,22 X3 ; Y3(Throughput apart mesokarp, g / men = - 0,748 - 0,297 X1 + 0,111 X2 + 0,336 X3 ; Y4 (percent heavy of mesokarp = 60,12 - 0,044 X1 + 0,018 X2 - 0,103 X3 ; Y5 ( Amount of kernel break = - 1,515 - 0,06 X1+ 0,035 X2 + 0,115 X3 ; Y6 ( FFA = - 0,655 + 0,011 X1 + 0,029 X2 + 0,032 X3 and  Y7 ( DOBI = 5,205 - 0,001 X1 + 0,01 X2 - 0,024 X3. Time depth steaming correct to braise small FFB, unrippe = 95 minute with score assess 7; Small FFB, mature = 95 minute with score assess 6; Small FFB over  mature = 90 minute with score assess 6. Time depth steaming correct for big FFB, unrippe = 100 minute with wight assess 6; Big FFB mature = 80 minute with score assess 5 and for big FFB, over mature = 95 minute with score assess 6.

Model and control scheme for recirculation mode direct steam generation parabolic trough solar power plants

International Nuclear Information System (INIS)

Guo, Su; Liu, Deyou; Chen, Xingying; Chu, Yinghao; Xu, Chang; Liu, Qunming; Zhou, Ling

2017-01-01

Highlights: •A nonlinear dynamic model of recirculation DSG parabolic trough is developed. •Collector row, water separator and spray attemperator are modeled, respectively. •The dynamic behaviors of the collector field are simulated and analyzed. •Transfer functions of water level and outlet fluid temperature are derived. •Multi-model switching generalized predictive control strategy is developed. -- Abstract: This work describes and evaluates a new nonlinear dynamic model, and a new generalized predictive control scheme for a collector field of direct steam generation parabolic troughs in recirculation mode. Modeling the dynamic behaviors of collector fields is essential to design, testing and validation of automatic control systems for direct steam generation parabolic troughs. However, the behaviors of two-phase heat transfer fluids impose challenges to simulating and developing process control schemes. In this work, a new nonlinear dynamic model is proposed, based on the nonlinear distributed parameter and the nonlinear lumped parameter methods. The proposed model is used to simulate and analyze the dynamic behaviors of the entire collector field for recirculation mode direct steam generation parabolic troughs under different weather conditions, without excessive computational costs. Based on the proposed model, transfer functions for both the water level of the separator and outlet steam temperatures are derived, and a new multi-model switching generalized predictive control scheme is developed for simulated control of the plant behaviors for a wide region of operational conditions. The proposed control scheme achieves excellent control performance and robustness for systems with long delay, large inertia and time-varying parameters, and efficiently solves the model mismatching problem in direct steam generation parabolic troughs. The performances of the model and control scheme are validated with design data from the project of Integration of Direct

Validation of the efficacy of a solar-thermal powered autoclave system for off-grid medical instrument wet sterilization.

Science.gov (United States)

Kaseman, Tremayne; Boubour, Jean; Schuler, Douglas A

2012-10-01

This work describes the efficacy of a solar-thermal powered autoclave used for the wet sterilization of medical instruments in off-grid settings where electrical power is not readily available. Twenty-seven trials of the solar-thermal powered system were run using an unmodified non-electric autoclave loaded with a simulated bundle of medical instruments and biological test agents. Results showed that in 100% of the trials the autoclave achieved temperatures in excess of 121°C for 30 minutes, indicator tape displayed visible reactions to steam sterilization, and biological tests showed that microbial agents had been eliminated, in compliance with the Centers for Disease Control and Prevention requirements for efficacious wet sterilization.

Computerized operating cost model for industrial steam generation

Energy Technology Data Exchange (ETDEWEB)

Powers, T.D.

1983-02-01

Pending EPA regulations, establishing revised emission levels for industrial boilers are perceived to have an effect on the relative costs of steam production technologies. To aid in the comparison of competitive boiler technologies, the Steam Cost Code was developed which provides levelized steam costs reflecting the effects of a number of key steam cost parameters. The Steam Cost Code is a user interactive FORTRAN program designed to operate on a VAX computer system. The program requires the user to input a number of variables describing the design characteristics, capital costs, and operating conditions for a specific boiler system. Part of the input to the Steam Cost Code is the capital cost of the steam production system. The capital cost is obtained from a program called INDCEPT, developed by Oak Ridge National Laboratory under Department of Energy, Morgantown Energy Technology Center sponsorship.

Sterilization of health care products - Radiation. Part 2: Establishing the sterilization dose

International Nuclear Information System (INIS)

2006-01-01

This part of ISO 11137 describes methods that may be used to establish the sterilization dose in accordance with one of the two approaches specified in 8.2 of ISO 11137-1:2006. The methods used in these approaches are: a) dose setting to obtain a product-specific dose; b) dose substantiation to verify a preselected dose of 25 kGy or 15 kGy. The basis of the dose setting methods described in this part of ISO 11137 (Methods 1 and 2) owe much to the ideas first propounded by Tallentire (Tallentire, 1973 [17]; Tallentire, Dwyer and Ley, 1971 [18]; Tallentire and Khan, 1978 [19]). Subsequently, standardized protocols were developed (Davis et al., 1981 [8]; Davis, Strawderman and Whitby, 1984 [9]) which formed the basis of the dose setting methods detailed in the AAMI Recommended Practice for Sterilization by Gamma Radiation (AAMI 1984, 1991 [4], [6]). Methods 1 and 2 and the associated sterilization dose audit procedures use data derived from the inactivation of the microbial population in its natural state on product. The methods are based on a probability model for the inactivation of microbial populations. The probability model, as applied to bioburden made up of a mixture of various microbial species, assumes that each such species has its own unique D 10 value. In the model, the probability that an item will possess a surviving microorganism after exposure to a given dose of radiation is defined in terms of the initial number of microorganisms on the item prior to irradiation and the D 10 values of the microorganisms. The methods involve performance of tests of sterility on product items that have received doses of radiation lower than the sterilization dose. The outcome of these tests is used to predict the dose needed to achieve a predetermined sterility assurance level, SAL. Methods 1 and 2 may also be used to substantiate 25 kGy if, on performing a dose setting exercise, the derived sterilization dose for an SAL of 10 -6 is u ≤25 kGy. The basis of the method

Modeling and dynamic simulation of U-tube steam generator

International Nuclear Information System (INIS)

Cui Zhenghua; Jia Dounan; Chen Xuejun; Yu Erjun

1992-01-01

An accurate and simple dynamic mathematical model of U-tube steam generator is presented. It is solved by Adams method and Gear method respectively. The results of this model are in good agreements with that of Kerlin's model which has been validated by the tests. And the two calculating methods are compared

Reionization in sterile neutrino cosmologies

Science.gov (United States)

Bose, Sownak; Frenk, Carlos S.; Hou, Jun; Lacey, Cedric G.; Lovell, Mark R.

2016-12-01

We investigate the process of reionization in a model in which the dark matter is a warm elementary particle such as a sterile neutrino. We focus on models that are consistent with the dark matter decay interpretation of the recently detected line at 3.5 keV in the X-ray spectra of galaxies and clusters. In warm dark matter models, the primordial spectrum of density perturbations has a cut-off on the scale of dwarf galaxies. Structure formation therefore begins later than in the standard cold dark matter (CDM) model and very few objects form below the cut-off mass scale. To calculate the number of ionizing photons, we use the Durham semi-analytic model of galaxy formation, GALFORM. We find that even the most extreme 7 keV sterile neutrino we consider is able to reionize the Universe early enough to be compatible with the bounds on the epoch of reionization from Planck. This, perhaps surprising, result arises from the rapid build-up of high redshift galaxies in the sterile neutrino models which is also reflected in a faster evolution of their far-UV luminosity function between 10 > z > 7 than in CDM. The dominant sources of ionizing photons are systematically more massive in the sterile neutrino models than in CDM. As a consistency check on the models, we calculate the present-day luminosity function of satellites of Milky Way-like galaxies. When the satellites recently discovered in the Dark Energy Survey are taken into account, strong constraints are placed on viable sterile neutrino models.

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)

French steam generator design developments

International Nuclear Information System (INIS)

Ginier, R.; Campan, J.L.; Pontier, M.; Leridon, A.; Remond, A.; Castello, G.; Holcblat, A.; Paurobally, H.

1986-01-01

From the outset of the French nuclear power program, a significant R and D effort has been invested in improvement of the design and operation of Pressurized Water Reactors including a special committment to improving steam generators. The steam generator enhancement program has spawned a wide variety of specific R and D resources, e.g., low temperature hydraulic models for investigation of areas with single-phase flow, and freon-filled models for simulation of areas of steam generators experiencing two-phase flow (tube bundles and moisture separators). For the moisture separators, a large scale research program using freon-filled models and highly sophisticated instrumentation was used. Tests at reactor sites during startup of both 900 MWe and 1300 MWe have been used to validate the assumptions made on the basis of loop tests. These tests also demonstrated the validity of using freon to simulate two-phase flow conditions. The wealth of knowledge accumulated by the steam generator R and D program has been used to develop a new design of steam generators for the N4 plants. The current R and D effort is aimed at qualifying the N4 steam generator model and developing more comprehensive models. One prong of the R and D effort is the Megeve program. Megeve is a 25 MW steam generator which simulates operating conditions of the N4 model. The other prong is Clotaire, a freon-filled steam generator model which will be used to qualify thermal/hydraulic design codes used for multidimensional calculations for design of tube bundles

Postpartum Sterilization

Science.gov (United States)

f AQ FREQUENTLY ASKED QUESTIONS FAQ052 CONTRACEPTION Postpartum Sterilization • What is sterilization? • What is postpartum sterilization? • How is postpartum sterilization performed? • What kind of anesthesia is used for postpartum sterilization? • How ...

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.

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,…

Feasibility Study on Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation

International Nuclear Information System (INIS)

Jung, Inha

2013-12-01

This report on the 'Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation' is belonged to the final report on the preliminary study of the first subject in 2013 for civilian project. This was complimented on the responsible of the Korea Atomic Energy Research Institute for 1 st of June 2013 to 30 th of November 2013. We are going to make sterilization the badge using the gamma ray and supplying the oxygen by nano-bubble oxygen rich water for cultivating the Matsutake Mushroom, instead of the conventional process of sterilization of the badge by hot steam over 120 .deg. C consuming over 8 hours and expensive ventilation system for supplying the fresh air for delivering the oxygen

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)

Modeling of steam generator in nuclear power plant using neural network ensemble

International Nuclear Information System (INIS)

Lee, S. K.; Lee, E. C.; Jang, J. W.

2003-01-01

Neural network is now being used in modeling the steam generator is known to be difficult due to the reverse dynamics. However, Neural network is prone to the problem of overfitting. This paper investigates the use of neural network combining methods to model steam generator water level and compares with single neural network. The results show that neural network ensemble is effective tool which can offer improved generalization, lower dependence of the training set and reduced training time

Mathematical Modeling of Ultra-Superheated Steam Gasification

Science.gov (United States)

Xin, Fen

Pure steam gasification has been of interest in hydrogen production, but with the challenge of supplying heat for endothermic reactions. Traditional solutions included either combusting feedstocks at the price of decreasing carbon conversion ratio, or using costly heating apparatus. Therefore, a distributed gasifier with an Ultra-Superheated-Steam (USS) generator was invented, satisfying the heat requirement and avoiding carbon combustion in steam gasification. This project developed the first version of the Ultra-Superheated-Steam-Fluidization-Model (USSFM V1.0) for the USS gasifier. A stand-alone equilibrium combustion model was firstly developed to calculate the USS mixture, which was the input to the USSFM V1.0. Model development of the USSFM V1.0 included assumptions, governing equations, boundary conditions, supporting equations and iterative schemes of guessed values. There were three nested loops in the dense bed and one loop in the freeboard. The USSFM V1.0 included one main routine and twenty-four subroutines. The USSFM V1.0 was validated with experimental data from the Enercon USS gasifier. The calculated USS mixture had a trace of oxygen, validating the initial expectation of creating an oxygen-free environment in the gasifier. Simulations showed that the USS mixture could satisfy the gasification heat requirement without partial carbon combustion. The USSFM V1.0 had good predictions on the H2% in all tests, and on other variables at a level of the lower oxygen feed. Provided with higher oxygen feed, the USSFM V1.0 simulated hotter temperatures, higher CO% and lower CO2%. Errors were explained by assumptions of equilibrium combustion, adiabatic reactors, reaction kinetics, etc. By investigating specific modeling data, gas-particle convective heat transfers were found to be critical in energy balance equations of both emulsion gas and particles, while bubble size controlled both the mass and energy balance equations of bubble gas. Parametric study

Hysteroscopic Sterilization

Science.gov (United States)

... sterilization? Sterilization is a permanent form of birth control. What is tubal sterilization? Sterilization procedures for women are ... is quicker than from other types of sterilization. What are the risks of ... on for birth control. • There is a risk of injury to the ...

Effects of sterilization treatments on bulk and surface properties of nanocomposite biomaterials.

Science.gov (United States)

Ahmed, Maqsood; Punshon, Geoffrey; Darbyshire, Arnold; Seifalian, Alexander M

2013-10-01

With the continuous and expanding use of implantable biomaterials in a clinical setting, this study aims to elucidate the influence of sterilization techniques on the material surface and bulk properties of two polyurethane nanocomposite biomaterials. Both solid samples and porous membranes of nondegradable polyhedral oligomeric silsesquioxane poly(carbonate-urea) urethane (POSS-PCU) and a biodegradable poly(caprolactone-urea) urethane (POSS-PCL) were examined. Sterilization techniques included conventional steam sterilization (autoclaving), gamma irradiation, and disinfection via incubating with ethanol (EtOH) for 10 min or 24 h. After treatment, the samples were examined using gel permeation chromatography (GPC), attenuated total reflectance Fourier transform infrared spectroscopy, and tensiometry. Cytotoxicity was evaluated through the culture of endothelial progenitor cells and the efficacy of sterilization method was determined by incubating each sample in tryptone soya broth and fluid thioglycollate medium for cultivation of microorganisms. Although EtOH did not affect the material properties in any form, the samples were found to be nonsterile with microbial growth detected on each of the samples. Gamma irradiation was not only effective in sterilizing both POSS-PCU and POSS-PCL but also led to minor material degradation and displayed a cytotoxic effect on the cultured cells. Autoclaving was found to be the optimal sterilization technique for both solid and porous membranes of the nondegradable POSS-PCU samples as it was successful in sterilizing the samples, displayed no cytotoxic side effects and did not degrade the material. However, the biodegradable POSS-PCL was not able to withstand the harsh environment during autoclaving, resulting in it losing all structural integrity. Copyright © 2013 Wiley Periodicals, Inc., a Wiley Company.

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

Dynamic Modeling of Steam Condenser and Design of PI Controller Based on Grey Wolf Optimizer

OpenAIRE

Shu-Xia Li; Jie-Sheng Wang

2015-01-01

Shell-and-tube condenser is a heat exchanger for cooling steam with high temperature and pressure, which is one of the main kinds of heat exchange equipment in thermal, nuclear, and marine power plant. Based on the lumped parameter modeling method, the dynamic mathematical model of the simplified steam condenser is established. Then, the pressure PI control system of steam condenser based on the Matlab/Simulink simulation platform is designed. In order to obtain better performance, a new meta...

Analysis of a carcinogen, 4,4'-methylenedianiline, from thermosetting polyurethane during sterilization.

Science.gov (United States)

Shintani, H; Nakamura, A

1989-01-01

Polyurethane (PU) is widely used in medical devices such as potting material in artificial dialysis devices, plasma separators, etc. Gamma-ray irradiation is frequently used for the sterilization of such devices. This paper reports that a carcinogen, 4,4'-methylenedianiline (MDA, p,p'-diaminodiphenylmethane), is produced from medical thermosetting PU by gamma-ray irradiation. Gamma-ray irradiated PU was immersed in methanol or equine serum. The serum was treated with a mixture of 5N HCIO4:acetonitrile (1:10) in order to deproteinate and recover MDA. It was found that MDA is formed from thermosetting PU at around a few ppm in the original sample. The production of MDA increased with increasing irradiation dose. The MDA amount formed was related to the irradiation dose by a second order equation. Results of methanol and serum extraction were similar. Pressurized steam (autoclave) sterilization in place of gamma-ray sterilization was also examined. MDA production was not found in autoclave sterilization procedures. Gel permeation chromatography (GPC) of methanol or N,N-dimethylformamide (DMF) extract of irradiated PU showed that the PU oligomers eluted. Time course of methanol extract of irradiated PU was detected at 245.5 nm. This showed an exponential decline regardless of doses of irradiation.

Analysis of a carcinogen, 4,4'-methylenedianiline, from thermosetting polyurethane during sterilization

International Nuclear Information System (INIS)

Shintani, H.; Nakamura, A.

1989-01-01

Polyurethane (PU) is widely used in medical devices such as potting material in artificial dialysis devices, plasma separators, etc. Gamma-ray irradiation is frequently used for the sterilization of such devices. This paper reports that a carcinogen, 4,4'-methylenedianiline (MDA, p,p'-diaminodiphenylmethane), is produced from medical thermosetting PU by gamma-ray irradiation. Gamma-ray irradiated PU was immersed in methanol or equine serum. The serum was treated with a mixture of 5N HCIO4:acetonitrile (1:10) in order to deproteinate and recover MDA. It was found that MDA is formed from thermosetting PU at around a few ppm in the original sample. The production of MDA increased with increasing irradiation dose. The MDA amount formed was related to the irradiation dose by a second order equation. Results of methanol and serum extraction were similar. Pressurized steam (autoclave) sterilization in place of gamma-ray sterilization was also examined. MDA production was not found in autoclave sterilization procedures. Gel permeation chromatography (GPC) of methanol or N,N-dimethylformamide (DMF) extract of irradiated PU showed that the PU oligomers eluted. Time course of methanol extract of irradiated PU was detected at 245.5 nm. This showed an exponential decline regardless of doses of irradiation

U-tube steam generator modelling: application to level control and comparison with plant data

International Nuclear Information System (INIS)

Gautier, A.; Petetrot, J.F.; Roulet, A.; Ruiz, P.; Zwingelstein, G.

1979-01-01

A nonlinear multinode digital model of a recirculating U-tube steam generator is first described. Comparison between the model and Fessenheim and Bugey tests results on power step and full load rejection is given. These transients are of special interest because they provide information on the boiler high frequency response and also insights into steam generator non linear behaviour. An example of steam generator modelling as applied to control system design is then presented. This example demonstrates major improvement of control loop performance at low load following implementation of a non linear gain which allows more efficient control of large perturbations. Results of testing on the Bugey 4 plant are also indicated

Condensation of steam

International Nuclear Information System (INIS)

Prisyazhniuk, V.A.

2002-01-01

An equation for nucleation kinetics in steam condensation has been derived, the equation taking into account the concurrent and independent functioning of two nucleation mechanisms: the homogeneous one and the heterogeneous one. The equation is a most general-purpose one and includes all the previously known condensation models as special cases. It is shown how the equation can be used in analyzing the process of steam condensation in the condenser of an industrial steam-turbine plant, and in working out new ways of raising the efficiency of the condenser, as well as of the steam-turbine plant as a whole. (orig.)

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.

Modeling and optimization of a utility system containing multiple extractions steam turbines

International Nuclear Information System (INIS)

Luo, Xianglong; Zhang, Bingjian; Chen, Ying; Mo, Songping

2011-01-01

Complex turbines with multiple controlled and/or uncontrolled extractions are popularly used in the processing industry and cogeneration plants to provide steam of different levels, electric power, and driving power. To characterize thermodynamic behavior under varying conditions, nonlinear mathematical models are developed based on energy balance, thermodynamic principles, and semi-empirical equations. First, the complex turbine is decomposed into several simple turbines from the controlled extraction stages and modeled in series. THM (The turbine hardware model) developing concept is applied to predict the isentropic efficiency of the decomposed simple turbines. Stodola's formulation is also used to simulate the uncontrolled extraction steam parameters. The thermodynamic properties of steam and water are regressed through linearization or piece-wise linearization. Second, comparison between the simulated results using the proposed model and the data in the working condition diagram provided by the manufacturer is conducted over a wide range of operations. The simulation results yield small deviation from the data in the working condition diagram where the maximum modeling error is 0.87% among the compared seven operation conditions. Last, the optimization model of a utility system containing multiple extraction turbines is established and a detailed case is analyzed. Compared with the conventional operation strategy, a maximum of 5.47% of the total operation cost is saved using the proposed optimization model. -- Highlights: → We develop a complete simulation model for steam turbine with multiple extractions. → We test the simulation model using the performance data of commercial turbines. → The simulation error of electric power generation is no more than 0.87%. → We establish a utility system operational optimization model. → The optimal industrial operation scheme featured with 5.47% of cost saving.

Local two-phase modeling of the water-steam flows occurring in steam generators

International Nuclear Information System (INIS)

Denefle, Romain

2013-01-01

The present study is related to the need of modeling the two-phase flows occurring in a steam generator (liquid at inlet and vapour at outlet). The choice is made to investigate a hybrid modeling of the flow, considering the gas phase as two separated fields, each one being modeled with different closure laws. In so doing, the small and spherical bubbles are modeled through a dispersed approach within the two-fluid model, and the distorted bubbles are simulated with an interface locating method. The main outcome is about the implementation, the verification and the validation of the model dedicated to the large and distorted bubbles, as well as the coupling of the two approaches for the gas, allowing the presentation of demonstration calculations using the so-called hybrid approach. (author)

Trends in sterilization since the introduction of Essure hysteroscopic sterilization.

Science.gov (United States)

Shavell, Valerie I; Abdallah, Mazen E; Shade, George H; Diamond, Michael P; Berman, Jay M

2009-01-01

To investigate trends in sterilization in women at the Detroit Medical Center, Michigan (DMC), since the introduction of Essure hysteroscopic sterilization. Retrospective study (Canadian Task Force classification II-2). Outpatient surgery center and university teaching hospitals. Women who underwent interval sterilization procedures at the DMC (Hutzel Women's Hospital, Sinai-Grace Hospital, and the Berry Center) and postpartum sterilization procedures at Hutzel Women's Hospital between January 1, 2002, and December 31, 2007. Permanent sterilization procedures including minilaparotomy tubal ligation, laparoscopic sterilization, Essure hysteroscopic sterilization, and postpartum tubal ligation performed at the time of cesarean section or after vaginal delivery. In all, 5509 permanent sterilization procedures were performed in the 6 years between January 1, 2002, and December 31, 2007, at the DMC facilities analyzed: 2484 interval sterilization procedures at Hutzel Women's Hospital, Sinai-Grace Hospital, and the Berry Center, and 3025 postpartum tubal ligations at Hutzel Women's Hospital. From 2002 through 2007, the decrease in laparoscopic sterilizations from 97.9% to 48.5% of all interval sterilization procedures corresponded significantly with the increase in Essure hysteroscopic sterilizations from 0.0% to 51.3% (p Essure hysteroscopic sterilizations increased significantly from 0.0% to 51.3% of all procedures. Since the approval of Essure hysteroscopic sterilization in November 2002, this minimally invasive method of hysteroscopic sterilization has increased in popularity at the DMC.

Mathematical modeling of control system for the experimental steam generator

Science.gov (United States)

Podlasek, Szymon; Lalik, Krzysztof; Filipowicz, Mariusz; Sornek, Krzysztof; Kupski, Robert; Raś, Anita

2016-03-01

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.

Feasibility Study on Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation

Energy Technology Data Exchange (ETDEWEB)

Jung, Inha

2013-12-15

This report on the 'Sterilization of Badge using Radiation and Cultivation by Nano-bubble Water for Matsutake Mushroom Cultivation' is belonged to the final report on the preliminary study of the first subject in 2013 for civilian project. This was complimented on the responsible of the Korea Atomic Energy Research Institute for 1{sup st} of June 2013 to 30{sup th} of November 2013. We are going to make sterilization the badge using the gamma ray and supplying the oxygen by nano-bubble oxygen rich water for cultivating the Matsutake Mushroom, instead of the conventional process of sterilization of the badge by hot steam over 120 .deg. C consuming over 8 hours and expensive ventilation system for supplying the fresh air for delivering the oxygen.

A two-fluid two-phase model for thermal-hydraulic analysis of a U-tube steam generator

International Nuclear Information System (INIS)

Hung, Huanjen; Chieng, Chingchang; Pei, Baushei; Wang, Songfeng

1993-01-01

The Advanced Thermal-Hydraulic Analysis Code for Nuclear Steam Generators (ATHANS) was developed on the basis of the THERMIT-UTSG computer code for U-tube steam generators. The main features of the ATHANS model are as follows: (a) the equations are solved in cylindrical coordinates, (b) the number and the arrangement of the control volumes inside the steam generator can be chosen by the user, (c) the virtual mass effect is incorporated, and (d) the conjugate gradient squared method is employed to accelerate and improve the numerical convergence. The performance of the model is successfully validated by comparison with the test data from a Westinghouse model F steam generator at the Maanshan nuclear power plant. Better agreement with the test data can be obtained by a finer grid system using a cylindrical coordinate system and the virtual mass effect. With these advanced features, ATHANS provides the basic framework for further studies on the problems of steam generators, such as analyses of secondary-side corrosion and tube ruptures

Dark-matter sterile neutrinos in models with a gauge singlet in the Higgs sector

International Nuclear Information System (INIS)

Petraki, Kalliopi; Kusenko, Alexander

2008-01-01

Sterile neutrino with mass of several keV can be the cosmological dark matter, can explain the observed velocities of pulsars, and can play an important role in the formation of the first stars. We describe the production of sterile neutrinos in a model with an extended Higgs sector, in which the Majorana mass term is generated by the vacuum expectation value of a gauge-singlet Higgs boson. In this model the relic abundance of sterile neutrinos does not necessarily depend on their mixing angles, the free-streaming length can be much smaller than in the case of warm dark matter produced by neutrino oscillations, and, therefore, some of the previously quoted bounds do not apply. The presence of the gauge singlet in the Higgs sector has important implications for the electroweak phase transition, baryogenesis, and the upcoming experiments at the Large Hadron Collider and a Linear Collider.

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

Theoretical-experimental modelling of the momentum equation for PWR reactor steam generators

International Nuclear Information System (INIS)

Rodrigues, L.A.H.

1994-01-01

A mathematical model in steady-state conditions of the momentum equation at the secondary side of a vertical U-tube steam generator with recirculation is presented. The U-tube test section was the 150 bar - Circuito Termoidraulico Experimental - CTE-150. This facility is a Experimental Thermal-hydraulic Circuit and operates at the same conditions (pressure and temperature) of a typical PWR reactor. A comparison between the Homogeneous and Separate Flow models was done. those models were verified and compared with experimental data for several operational conditions. The results show that the model fits very well the experimental data and seems to be appropriate to study water recirculation of a steam generator secondary side. (author)

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.

Analysis of experimental characteristics of multistage steam-jet electors of steam turbines

Science.gov (United States)

Aronson, K. E.; Ryabchikov, A. Yu.; Brodov, Yu. M.; Brezgin, D. V.; Zhelonkin, N. V.; Murmanskii, I. B.

2017-02-01

A series of questions for specification of physical gas dynamics model in flow range of steam-jet unit and ejector computation methodology, as well as functioning peculiarities of intercoolers, was formulated based on analysis of experimental characteristics of multistage team-jet steam turbines. It was established that coefficient defining position of critical cross-section of injected flow depends on characteristics of the "sound tube" zone. Speed of injected flow within this tube may exceed that of sound, and pressure jumps in work-steam decrease at the same time. Characteristics of the "sound tube" define optimal axial sizes of the ejector. According to measurement results, the part of steam condensing in the first-stage coolant constitutes 70-80% of steam amount supplied into coolant and is almost independent of air content in steam. Coolant efficiency depends on steam pressure defined by operation of steam-jet unit of ejector of the next stage after coolant of steam-jet stage, temperature, and condensing water flow. As a rule, steam entering content of steam-air mixture supplied to coolant is overheated with respect to saturation temperature of steam in the mixture. This should be taken into account during coolant computation. Long-term operation causes changes in roughness of walls of the ejector's mixing chamber. The influence of change of wall roughness on ejector characteristic is similar to the influence of reverse pressure of the steam-jet stage. Until some roughness value, injection coefficient of the ejector stage operating in superlimiting regime hardly changed. After reaching critical roughness, the ejector switches to prelimiting operating regime.

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.

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.

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.

Phenomenological modelling of steam explosions

International Nuclear Information System (INIS)

Corradini, M.L.; Drumheller, D.S.

1980-01-01

During a hypothetical core meltdown accident, an important safety issue to be addressed is the potential for steam explosions. This paper presents analysis and modelling of experimental results. There are four observations that can be drawn from the analysis: (1) vapor explosions are suppressed by noncondensible gases generated by fuel oxidation, by high ambient pressure, and by high water temperatures; (2) these effects appear to be trigger-related in that an explosion can again be induced in some cases by increasing the trigger magnitude; (3) direct fuel liquid-coolant liquid contact can explain small scale fuel fragmentation; (4) heat transfer during the expansion phase of the explosion can reduce the work potential

Freeze-in production of sterile neutrino dark matter in U(1){sub B−L} model

Energy Technology Data Exchange (ETDEWEB)

Biswas, Anirban; Gupta, Aritra [Harish-Chandra Research Institute,Chhatnag Road, Jhunsi, Allahabad 211 019 (India)

2016-09-27

With the advent of new and more sensitive direct detection experiments, scope for a thermal WIMP explanation of dark matter (DM) has become extremely constricted. The non-observation of thermal WIMP in these experiments has put a strong upper bound on WIMP-nucleon scattering cross section and within a few years it is likely to overlap with the coherent neutrino-nucleon cross section. Hence in all probability, DM may have some non-thermal origin. In this work we explore in detail this possibility of a non-thermal sterile neutrino DM within the framework of U(1){sub B−L} model. The U(1){sub B−L} model on the other hand is a well-motivated and minimal way of extending the standard model so that it can explain the neutrino masses via Type-I see-saw mechanism. We have shown, besides explaining the neutrino mass, it can also accommodate a non-thermal sterile neutrino DM with correct relic density. In contrast with the existing literature, we have found that W{sup ±} decay can also be a dominant production mode of the sterile neutrino DM. To obtain the comoving number density of dark matter, we have solved here a coupled set of Boltzmann equations considering all possible decay as well as annihilation production modes of the sterile neutrino dark matter. The framework developed here though has been done for a U(1){sub B−L} model, can be applied quite generally for any models with an extra neutral gauge boson and a fermionic non-thermal dark matter.

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...

Modeling and field studies of fouling in once-through steam generators

International Nuclear Information System (INIS)

Thompson, R.; Gaudreau, T.

1995-01-01

Efforts of the past 10 years to minimize fouling of the Crystal River-3 once-through steam generators are reviewed. The major focus has been on improving at-temperature pH control in the secondary cycle. Various concentrations of different pH control agents were tested in the field for hundreds of days to determine their effect on steam generator fouling. High concentrations of morpholine (50--100 ppm) in the feedwater were found to apparently produce de-fouling of the steam generators without an associated decrease in feedwater iron concentration as compared to that at lower levels of morpholine. Computer modeling of the pH(t) within the OTSG for the various chemistries tested indicates that the pH can change significantly with elevation within the steam generator by varying the pH control agent or its concentration. It is postulated that these variations in pH may change the surface charge of the tubes, tube support plates, and/or corrosion product particles in solution, to favor either deposition or repulsion of the particles, and thereby producing conditions that either favor fouling or de-fouling of the OTSG. Crystal River-3 experience indicates that corrosion product deposition and release processes inside the steam generator can be chemically manipulated to favor release, and thereby maximize plant performance, and delay or avoid costly hydraulic or chemical cleanings

Two dimensional numerical model for steam--water flow in a sudden contraction

International Nuclear Information System (INIS)

Crowe, C.T.; Choi, H.N.

1976-01-01

A computational model developed for two-dimensional dispersed two-phase flows is applied to steam--water flow in a sudden contraction. The calculational scheme utilizes the cellular approach in which each cell is regarded as a control volume and the droplets are regarded as sources of mass, momentum and energy to the conveying (steam) phase. The predictions show how droplets channel in the entry region and affect the velocity and pressure distributions along the duct

Particle deposition modeling in the secondary side of a steam generator bundle model

Energy Technology Data Exchange (ETDEWEB)

Mukin, Roman, E-mail: roman.mukin@psi.ch; Dehbi, Abdel, E-mail: abdel.dehbi@psi.ch

2016-04-01

A steam generator (SG) tube rupture (SGTR) model is studied in this paper. This model based on a experimental facility called Aerosol Trapping In a Steam Generator (ARTIST), which is a model of a scaled steam generator tube bundle consisting of 270 tubes and a guillotine tube to address aerosol deposition phenomena on two different scales: near the tube break, where the gas velocities and turbulence are very intensive, and far away from the break, where the flow velocities are three orders of magnitude lower. Owing to complexity of the flow, 3D simulations with highly resolved computational mesh near the break were done. First, the flow inside an isolated tube with a guillotine tube break has been studied in the framework of Reynolds Averaged Navier Stokes (RANS) approach. The next part is devoted to the simulation of an inclined gas jet entering the SG tube bundle via the guillotine tube breach with more advanced CFD tools. In particular, Detached Eddy Simulation (DES) and RANS are applied to tackle the wide range of flow scales. Flow field velocity comparison showed that DES results are reproducing wavy structure of the flow field in far field from the break observed in experiment. Particle transport and deposition is modelled by Lagrangian continuous random walk (CRW) model, which has been developed and validated previously. It is found that the DES combined with the CRW to supply fluctuating velocity components predicts deposition rates that are generally within the scatter of the measured data. Monodisperse, spherical SiO{sub 2} particles with AMMD = 1.4 μm were used as aerosol particles in simulations. To be economically feasible, the computations were made with the open source CFD code OpenFOAM. Comparison of the calculated flow with the experimental axial velocity distribution data at different vertical levels has been performed.

Effects of sterile neutrino and extra-dimension on big bang nucleosynthesis

Science.gov (United States)

Jang, Dukjae; Kusakabe, Motohiko; Cheoun, Myung-Ki

2018-04-01

We study effects of the sterile neutrino in the five-dimensional universe on the big bang nucleosynthesis (BBN). Since the five-dimensional universe model leads to an additional term in the Friedmann equation and the energy density of the sterile neutrino increases the total energy density, this model can affect the primordial abundance via changing the cosmic expansion rate. The energy density of the sterile neutrino can be determined by a rate equation for production of the sterile neutrino. We show that not only the mixing angle and the mass of the sterile neutrino, but also a resonant effect in the oscillation between sterile and active neutrinos is important to determine a relic abundance of the sterile neutrino. In this study, we also investigate how the sterile neutrino in extra-dimensional model can affect the BBN, and constrain the parameters related to the above properties of the sterile neutrino by using the observational primordial abundances of light elements.

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.

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

Modeling, Simulation and Optimization of Hydrogen Production Process from Glycerol using Steam Reforming

International Nuclear Information System (INIS)

Park, Jeongpil; Cho, Sunghyun; Kim, Tae-Ok; Shin, Dongil; Lee, Seunghwan; Moon, Dong Ju

2014-01-01

For improved sustainability of the biorefinery industry, biorefinery-byproduct glycerol is being investigated as an alternate source for hydrogen production. This research designs and optimizes a hydrogen-production process for small hydrogen stations using steam reforming of purified glycerol as the main reaction, replacing existing processes relying on steam methane reforming. Modeling, simulation and optimization using a commercial process simulator are performed for the proposed hydrogen production process from glycerol. The mixture of glycerol and steam are used for making syngas in the reforming process. Then hydrogen are produced from carbon monoxide and steam through the water-gas shift reaction. Finally, hydrogen is separated from carbon dioxide using PSA. This study shows higher yield than former U.S.. DOE and Linde studies. Economic evaluations are performed for optimal planning of constructing domestic hydrogen energy infrastructure based on the proposed glycerol-based hydrogen station

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...

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)

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.

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....

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).

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 ("1"4"4Ce-"1"4"4Pr) and possibly neutrino source ("5"1Cr) 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).

[Assessment of disinfection and sterilization processes in dental practice as an important factors in prevention of infections].

Science.gov (United States)

Podgórska, Marta; Jakimiak, Bozenna; Röhm-Rodowald, Ewa; Chojecka, Agnieszka

2009-01-01

The dental health-care settings is an environment where disease transmission occurs easily. Prevention of cross infection is therefore a crucial aspect of dental practice and dental clinic stuffmust adopt certain basic routines while practicing. Infections may be transmitted in the dental operatory through direct contact with blood, oral fluids or other secretions; via indirect contact with contaminated instruments, equipment or environmental surfaces; or by contact with airborne contaminants present in either droplet splatter or aerosols of oral and respiratory fluids. Strategies to prevent dental patient infections have focused on disinfection and sterilization. This study evaluates basic routines in prevention of cross-infection in the dentistry. The sample comprised 100 dentists, who completed questionnaires. Based on inquires the conditions for disinfection and sterilization of medical devices were assessed. The following issues were taken into consideration: the way of disinfection and preparation of the disinfectants, the localization of disinfection, preparing to disinfection, washing and packing of dental devices, the frequency of disinfection, methods of sterilization and the monitoring system, type of sterilizers and the available cycles. The dental practices are well equiped to proceed the steam sterilization, but 33% of dentists don't know the available cycles in their autoclaves. Only 35% of them made sterilization process protocols. Very common are three failures of instruments disinfections: multiple use of disinfectant, adding of disinfectant, adding new instruments. There is still need for improvement in disinfection and sterilization in dental practice, especially including: monitoring and documentation of sterilization process, proper use of disinfectants according to manufactures instructions, frequent disinfection of surfaces which contact with patients. Dental stuff should take part in advanced training courses about disinfection and

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.

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)

1996-12-31

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.

Radiation sterilization

International Nuclear Information System (INIS)

Jacobs, G.P.

1989-01-01

In view of the application of ionizing radiation to sterilize pharmaceutical products, and the particular advantages of using this mode of sterilization for powders for injection, which cannot be sterilized by more conventional methods, it is important to recognise the possibility of modification of radiation response of bacteria when in close contact with various drug powders. For this study, bacterial spores, which lend themselves to dessication, and which can be dried onto an inert powder matrix, were chosen as the test system. The results of this work indicate that the additives tested have a modest protective effect on the spores. However, when considering a bacterial inactivation for sterilization purposes of between six and ten orders of magnitude, that is, a desired sterility assurance level of an expected maximum probability of a product item being non-sterile of 10 -6 , then the slight protective effect observed in this study approaches insignificance

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

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

DEFF Research Database (Denmark)

Psaraftis, Harilaos N.; Kontovas, Christos A.

2015-01-01

burned. The purpose of this chapter is to examine the practice of slow steaming from various angles. In that context, a taxonomy of models is presented, some fundamentals are outlined, the main trade-offs are analysed, and some decision models are presented. Some examples are finally presented so...

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.

Digital simulation for nuclear once-through steam generators

International Nuclear Information System (INIS)

Chen, A.T.

1976-01-01

Mathematical models for calculating the dynamic response of the Oconee type once through steam generator (OTSG) and the integral economizer once through steam generator (IEOTSG) was developed and presented in this dissertation. Linear and nonlinear models of both steam generator types were formulated using the state variable, lumped parameter approach. Transient and frequency responses of system parameters were calculated for various perturbations from both the primary coolant side and the secondary side. Transients of key parameters, including primary outlet temperature, superheated steam outlet temperature, boiling length/subcooled length and steam pressure, were generated, compared and discussed for both steam generator types. Frequency responses of delta P/sub s//deltaT/sub pin/ of the linear OTSG model were validated by using the dynamic testing results obtained at the Oconee I nuclear power station. A sensitivity analysis in both the time and the frequency domains was performed. It was concluded that the mathematical and computer models developed in this dissertation for both the OTSG and the IEOTSG are suitable for overall plant performance evaluation and steam generator related component/system design analysis for nuclear plants using either type of steam generator

Steam generator tube rupture (SGTR) scenarios

International Nuclear Information System (INIS)

Auvinen, A.; Jokiniemi, J.K.; Laehde, A.; Routamo, T.; Lundstroem, P.; Tuomisto, H.; Dienstbier, J.; Guentay, S.; Suckow, D.; Dehbi, A.; Slootman, M.; Herranz, L.; Peyres, V.; Polo, J.

2005-01-01

The steam generator tube rupture (SGTR) scenarios project was carried out in the EU 5th framework programme in the field of nuclear safety during years 2000-2002. The first objective of the project was to generate a comprehensive database on fission product retention in a steam generator. The second objective was to verify and develop predictive models to support accident management interventions in steam generator tube rupture sequences, which either directly lead to severe accident conditions or are induced by other sequences leading to severe accidents. The models developed for fission product retention were to be included in severe accident codes. In addition, it was shown that existing models for turbulent deposition, which is the dominating deposition mechanism in dry conditions and at high flow rates, contain large uncertainties. The results of the project are applicable to various pressurised water reactors, including vertical steam generators (western PWR) and horizontal steam generators (VVER)

Sterile neutrinos as dark matter

International Nuclear Information System (INIS)

Dodelson, S.; Widrow, L.M.

1994-01-01

The simplest model that can accommodate a viable nonbaryonic dark matter candidate is the standard electroweak theory with the addition of right-handed (sterile) neutrinos. We consider a single generation of neutrinos with a Dirac mass μ and a Majorana mass M for the right-handed component. If M much-gt μ (standard hot dark matter corresponds to M=0), then sterile neutrinos are produced via oscillations in the early Universe with energy density independent of M. However, M is crucial in determining the large scale structure of the Universe; for M∼100 eV, sterile neutrinos make an excellent warm dark matter candidate

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

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 ...

Sterile neutrino

International Nuclear Information System (INIS)

Anon.

2007-01-01

Paper deals with the information on the occurrence of the fields of the sterile neutrinos (the righthanded ones) mixed with the normal neutrinos (the lefthanded ones). Both the Max Plank Radioastronomy Institute and the Los Angeles University assumes that the occurrence of the keV mass sterile neutrinos may explain the dark matter nature, the fast rotation of the observed pulsars and the reionization processes. The issues associated with the possibility to record the sterile neutrinos were analyzed in the course of the Sterile Neutrinos in Astrophysics and Cosmology Workshop (Crans Montana, March 2006 [ru

Rapid Generation of Superheated Steam Using a Water-containing Porous Material

Science.gov (United States)

Mori, Shoji; Okuyama, Kunito

Heat treatment by superheated steam has been utilized in several industrial fields including sterilization, desiccation, and cooking. In particular, cooking by superheated steam is receiving increased attention because it has advantages of reducing the salt and fat contents in foods as well as suppressing the oxidation of vitamin C and fat. In this application, quick startup and cut-off responses are required. Most electrically energized steam generators require a relatively long time to generate superheated steam due to the large heat capacities of the water in container and of the heater. Zhao and Liao (2002) introduced a novel process for rapid vaporization of subcooled liquid, in which a low-thermal-conductivity porous wick containing water is heated by a downward-facing grooved heating block in contact with the upper surface of the wick structure. They showed that saturated steam is generated within approximately 30 seconds from room-temperature water at a heat flux 41.2 kW⁄m2. In order to quickly generate superheated steam of approximately 300°C, which is required for cooking, the heat capacity of the heater should be as small as possible and the imposed heat flux should be so high enough that the porous wick is able to dry out in the vicinity of the contact with the heater and that the resulting heater temperature becomes much higher than the saturation temperature. The present paper proposes a simple structured generator to quickly produce superheated steam. Only a fine wire heater is contacted spirally on the inside wall in a hollow porous material. The start-up, cut-off responses and the rate of energy conversion for input power are investigated experimentally. Superheated steam of 300°C is produced in approximately 19 seconds from room-temperature water for an input power of 300 W. The maximum rate of energy conversion in the steady state is approximately 0.9.

Gamma-sterilization

International Nuclear Information System (INIS)

Lindgren, E.

1974-01-01

The author makes a survey of his experience in sterilization and sterility control of medical products. At present three different methods are used, steamsterilization, gassterilizing and gammasterilizing. The investments and costs for gamma radiation is presented and a comparison of the costs for gamma- and gassterilization including sterility control is made. (M.S.)

Model business plan for a sterile insect production facility

International Nuclear Information System (INIS)

2008-01-01

For over 50 years the sterile insect technique (SIT) is a pest control strategy which has been used for eradication, and more recently for suppression, containment and prevention, of unwanted insect pest populations. Examples of successful applications of SIT, almost always applied in conjunction with other control methods in an area-wide integrated approach, are available from around the world. The development and application of SIT has relied overwhelmingly on public or donor initiative and funding throughout its history, although the private sector has always been involved as participants, cooperators or partners in funding. The demand for SIT, and therefore the market for sterile insects, has increased in recent years. This increase coincides with the introduction of new pests through the expansion of global trade and, at the same time, widespread pressure to find alternatives to pesticides. Recent improvements in the technology supporting SIT facilitate its application and suggest lower costs can be achieved. The conditions are therefore met for a greater commercialization of the technique to bring it in line with other pest control approaches that are fully integrated into a market approach. Several challenges arise, however, in pursuing sterile insect production as a commercial venture, ranging from intellectual property protection to pricing of the product. Routine insurance requirements, for instance, are complicated by the biological aspects of the business. This report is aimed at facilitating private sector involvement in the production of sterile insects for use in pest control. It provides guidelines and tools to support the development of specific business plans for a new SIT venture. By providing an international perspective on such issues as initial capital costs and recurring operational expenditures for a sterile insect facility, it may be used to evaluate the feasibility of proceeding with the construction or expansion of a sterile insect

Numerical Analysis on Transient of Steam-gas Pressurizer

International Nuclear Information System (INIS)

Kim, Jong-Won; Lee, Yeon-Gun; Park, Goon-Cherl

2008-01-01

In nuclear reactors, various pressurizers are adopted to satisfy their characteristics and uses. The additional active systems such as heater, pressurizer cooler, spray and insulator are essential for a steam or a gas pressurizer. With a steam-gas pressurizer, additional systems are not required due to the use of steam and non-condensable gas as pressure-buffering materials. The steam-gas pressurizer in integrated small reactors experiences very complicated thermal-hydraulic phenomena. To ensure the integrity of this pressurizer type, the analysis on the transient behavior of the steam-gas pressure is indispensable. For this purpose, the steam-gas pressurizer model is introduced to predict the accurate system pressure. The proposed model includes bulk flashing, rainout, inter-region heat and mass transfer and wall condensation with non-condensable gas. However, the ideal gas law is not applied because of significant interaction at high pressure between steam and non-condensable gas. The results obtained from this proposed model agree with those from pressurizer tests. (authors)

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.)

The relative nutritive value of irradiated spray-dried blood powder and heat-sterilized blood meal as measured in combination with whey protein

International Nuclear Information System (INIS)

Downes, T.E.H.; Nourse, L.D.; Siebrits, F.K.; Hastings, J.W.

1987-01-01

A method of processing blood meal in which nutritive value of the protein is preserved is described, since appreciable losses occur in the nutritive value of the protein when prepared by heat sterilization with drying at atmospheric pressure in steam jacketed vessels. Blood was spray dried and irradiated at an intensity of 10 kGy. Collectively the heat of spray drying and irradiation was effective in killing both the virus plaque-forming units and the bacteria, thus producing a commercially acceptable sterile product of higher nutritive value. The relative nutritive values (RNV) of 50:50 protein were 0,56 for whey protein concentrate plus heat-sterilized blood meal and 0.90 for whey protein concentrate plus irradiated spray-dried blood powder. Whey protein concentrate used as a control has a RNV of 1,0

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

Evaluation of plugging criteria on steam generator tubes and coalescence model of collinear axial through-wall cracks

International Nuclear Information System (INIS)

Lee, Jin Ho; Park, Youn Won; Song, Myung Ho; Kim, Young Jin; Moon, Seong In

2000-01-01

In a nuclear power plant, steam generator tubes cover a major portion of the primary pressure-retaining boundary. Thus very conservative approaches have been taken in the light of steam generator tube integrity. According to the present criteria, tubes wall-thinned in excess 40% should be plugged whatever causes are. However, many analytical and experimental results have shown that no safety problems exist even with thickness reductions greater than 40%. The present criterion was developed about twenty years ago when wear and pitting were dominant causes for steam generator tube degradation. And it is based on tubes with single cracks regardless of the fact that the appearance of multiple cracks is more common in general. The objective of this study is to review the conservatism of the present plugging criteria of steam generator tubes and to propose a new coalescence model for two adjacent through-wall cracks existing in steam generator tubes. Using the existing failure models and experimental results, we reviewed the conservatism of the present plugging criteria. In order to verify the usefulness of the proposed new coalescence model, we performed finite element analysis and some parametric studies. Then, we developed a coalescence evaluation diagram

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.

Pressure-assisted thermal sterilization of soup

Science.gov (United States)

Shibeshi, Kidane; Farid, Mohammed M.

2010-12-01

The overall efficiency of an existing scale-up pressure-assisted thermal sterilization (PATS) unit was investigated with regards to inactivation of Geobacillus stearothermophilus spores suspended in pumpkin soup. The PATS unit is a double pipe heat exchanger in which the soup is pumped into its inner high pressure tube and constrained by two high pressure valves, while steam is continuously passed through the annular region to heat the content. The technology is based on pressure generation by thermal expansion of the liquid in an enclosure. In this work, the addition of an air line to push the treated liquid food out of the existing PATS unit has improved the overall quality of the treated samples, as evidenced by achieving higher log reduction of the spores. Compared with thermal processing, the application of PATS shows the potential for lowering the thermal treatment temperature, offering improved food quality.

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)

Thermoelastic steam turbine rotor control based on neural network

Science.gov (United States)

Rzadkowski, Romuald; Dominiczak, Krzysztof; Radulski, Wojciech; Szczepanik, R.

2015-12-01

Considered here are Nonlinear Auto-Regressive neural networks with eXogenous inputs (NARX) as a mathematical model of a steam turbine rotor for controlling steam turbine stress on-line. In order to obtain neural networks that locate critical stress and temperature points in the steam turbine during transient states, an FE rotor model was built. This model was used to train the neural networks on the basis of steam turbine transient operating data. The training included nonlinearity related to steam turbine expansion, heat exchange and rotor material properties during transients. Simultaneous neural networks are algorithms which can be implemented on PLC controllers. This allows for the application neural networks to control steam turbine stress in industrial power plants.

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.

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)

1998-12-31

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.

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'

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.

Predicting steam generator crevice chemistry

International Nuclear Information System (INIS)

Burton, G.; Strati, G.

2006-01-01

'Full text:' Corrosion of steam cycle components produces insoluble material, mostly iron oxides, that are transported to the steam generator (SG) via the feedwater and deposited on internal surfaces such as the tubes, tube support plates and the tubesheet. The build up of these corrosion products over time can lead to regions of restricted flow with water chemistry that may be significantly different, and potentially more corrosive to SG tube material, than the bulk steam generator water chemistry. The aim of the present work is to predict SG crevice chemistry using experimentation and modelling as part of AECL's overall strategy for steam generator life management. Hideout-return experiments are performed under CANDU steam generator conditions to assess the accumulation of impurities in hideout, and return from, model crevices. The results are used to validate the ChemSolv model that predicts steam generator crevice impurity concentrations, and high temperature pH, based on process parameters (e.g., heat flux, primary side temperature) and blowdown water chemistry. The model has been incorporated into ChemAND, AECL's system health monitoring software for chemistry monitoring, analysis and diagnostics that has been installed at two domestic and one international CANDU station. ChemAND provides the station chemists with the only method to predict SG crevice chemistry. In one recent application, the software has been used to evaluate the crevice chemistry based on the elevated, but balanced, SG bulk water impurity concentrations present during reactor startup, in order to reduce hold times. The present paper will describe recent hideout-return experiments that are used for the validation of the ChemSolv model, station experience using the software, and improvements to predict the crevice electrochemical potential that will permit station staff to ensure that the SG tubes are in the 'safe operating zone' predicted by Lu (AECL). (author)

Analysis and modeling of flow blockage-induced steam explosion events in the High-Flux Isotope Reactor

International Nuclear Information System (INIS)

Taleyarkhan, R.P.; Georgevich, V.; Lestor, C.W.; Gat, U.; Lepard, B.L.; Cook, D.H.; Freels, J.; Chang, S.J.; Luttrell, C.; Gwaltney, R.C.; Kirkpatrick, J.

1993-01-01

This paper provides a perspective overview of the analysis and modeling work done to evaluate the threat from steam explosion loads in the High-Flux Isotope Reactor during flow blockage events. The overall workscope included modeling and analysis of core melt initiation, melt propagation, bounding and best-estimate steam explosion energetics, vessel failure from fracture, bolts failure from exceedance of elastic limits, and finally, missile evolution and transport. Aluminum ignition was neglected. Evaluations indicated that a thermally driven steam explosion with more than 65 MJ of energy insertion in the core region over several miliseconds would be needed to cause a sufficiently energetic missile with a capacity to cause early confinement failure. This amounts to about 65% of the HFIR core mass melting and participating in a steam explosion. Conservative melt propagation analyses have indicated that at most only 24% of the HFIR core mass could melt during flow blockage events under full-power conditions. Therefore, it is judged that the HFIR vessel and top head structure will be able to withstand loads generated from thermally driven steam explosions initiated by any credible flow blockage event. A substantial margin to safety was demonstrated

Dark radiation sterile neutrino candidates after Planck data

Energy Technology Data Exchange (ETDEWEB)

Valentino, Eleonora Di; Melchiorri, Alessandro [Physics Department and INFN, Università di Roma ' ' La Sapienza' ' , Ple Aldo Moro 2, 00185, Rome (Italy); Mena, Olga, E-mail: eleonora.divalentino@roma1.infn.it, E-mail: alessandro.melchiorri@roma1.infn.it, E-mail: omena@ific.uv.es [IFIC, Universidad de Valencia-CSIC, 46071, Valencia (Spain)

2013-11-01

Recent Cosmic Microwave Background (CMB) results from the Planck satellite, combined with previous CMB data and Hubble constant measurements from the Hubble Space Telescope, provide a constraint on the effective number of relativistic degrees of freedom 3.62{sup +0.50}{sub −0.48} at 95% CL. New Planck data provide a unique opportunity to place limits on models containing relativistic species at the decoupling epoch. We present here the bounds on sterile neutrino models combining Planck data with galaxy clustering information. Assuming N{sub eff} active plus sterile massive neutrino species, in the case of a Planck+WP+HighL+HST analysis we find m{sub ν,} {sub sterile}{sup eff} < 0.36 eV and 3.14 < N{sub eff} < 4.15 at 95% CL, while using Planck+WP+HighL data in combination with the full shape of the galaxy power spectrum from the Baryon Oscillation Spectroscopic Survey BOSS Data Relase 9 measurements, we find that 3.30 < N{sub eff} < 4.43 and m{sub ν,} {sub sterile}{sup eff} < 0.33 eV both at 95% CL with the three active neutrinos having the minimum mass allowed in the normal hierarchy scheme, i.e. ∑m{sub ν} ∼ 0.06 eV. These values compromise the viability of the (3+2) massive sterile neutrino models for the parameter region indicated by global fits of neutrino oscillation data. Within the (3+1) massive sterile neutrino scenario, we find m{sub ν,} {sub sterile}{sup eff} < 0.34 eV at 95% CL. While the existence of one extra sterile massive neutrino state is compatible with current oscillation data, the values for the sterile neutrino mass preferred by oscillation analyses are significantly higher than the current cosmological bound. We review as well the bounds on extended dark sectors with additional light species based on the latest Planck CMB observations.

Analysis and modeling of flow-blockage-induced steam explosion events in the high-flux isotope reactor

International Nuclear Information System (INIS)

Taleyarkhan, R.P.; Georgevich, V.; Nestor, C.W.; Gat, U.; Lepard, B.L.; Cook, D.H.; Freels, J.; Chang, S.J.; Luttrell, C.; Gwaltney, R.C.

1994-01-01

This article provides a perspective overview of the analysis and modeling work done to evaluate the threat from steam explosion loads in the High-Flux Isotope Reactor (HFIR) during flow blockage events. The overall work scope included modeling and analysis of core-melt initiation, melt propagation, bounding and best-estimate steam explosion energetics, vessel failure from fracture, bolts failure from exceedance of elastic limits, and, finally, missile evolution and transport. Aluminum ignition was neglected. Evaluations indicated that a thermally driven steam explosion with more than 65 MJ of energy insertion in the core region over several milliseconds would be needed to cause a sufficiently energetic missile with a capacity to cause early confinement failure. This amounts to about 65% of the HFIR core mass melting and participating in a steam explosion. Conservative melt propagation analyses have indicated that at most only 24% of the HFIR core mass could melt during flow blockage events under full-power conditions. 19 refs., 11 figs

What do you mean you can't sterilize it? The reusable medical device matrix.

Science.gov (United States)

Stephens, Anne; Assang, AnnMarie

2010-12-01

begins with proper cleaning and processing of the surgical instruments. Surgical site infections can increase the length of stay and the cost of the patients' hospitalization, as well as increased risk, morbidity and even mortality. 1 Today's patients are far more informed than they were in the past. They can gather information from the internet as well as from television, radio, and print media. This knowledge empowers the patient to expect that their healthcare providers are practicing due diligence. It is the ethical duty and responsibility of nurses to provide safe, competent care while protecting the rights of the patient and being accountable to the professional governing bodies. In other words, we are advocates for both our patients and the healthcare system.2 Using both new and innovative instruments in the OR was, in the past, as simple as a surgeon requesting an instrument, the perioperative nurse ordering the instrument and CPD processing it for use in the OR. That is no longer the case. With a wide range of more complex instrumentation and an increasing focus on sterilization strategies, healthcare facilities have had to adopt a more rigorous approach. There are many challenges in the world of sterile processing. A common one, faced on a regular basis, is the provision of vague, inaccurate reprocessing recommendations from the medical device manufacturer. Canadian centres are not able to meet European standards for reprocessing. European cycles, often referred to as "Fractionated Steam Cycles", are different than the pre-vacuum steam cycles run in Canada.

Steam consumption minimization model in a multiple evaporation effect in a sugar plant

International Nuclear Information System (INIS)

Villada, Fernando; Valencia, Jaime A; Moreno, German; Murillo, J. Joaquin

1992-01-01

In this work, a mathematical model to minimize the steam consumption in a multiple effect evaporation system is shown. The model is based in the dynamic programming technique and the results are tested in a Colombian sugar mill

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)

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.

Development of a surrogate model for analysis of ex-vessel steam explosion in Nordic type BWRs

Energy Technology Data Exchange (ETDEWEB)

Grishchenko, Dmitry, E-mail: dmitry@safety.sci.kth.se; Basso, Simone, E-mail: simoneb@kth.se; Kudinov, Pavel, E-mail: pavel@safety.sci.kth.se

2016-12-15

Highlights: • Severe accident. • Steam explosion. • Surrogate model. • Sensitivity study. • Artificial neural networks. - Abstract: Severe accident mitigation strategy adopted in Nordic type Boiling Water Reactors (BWRs) employs ex-vessel core melt cooling in a deep pool of water below reactor vessel. Energetic fuel–coolant interaction (steam explosion) can occur during molten core release into water. Dynamic loads can threaten containment integrity increasing the risk of fission products release to the environment. Comprehensive uncertainty analysis is necessary in order to assess the risks. Computational costs of the existing fuel–coolant interaction (FCI) codes is often prohibitive for addressing the uncertainties, including the effect of stochastic triggering time. This paper discusses development of a computationally efficient surrogate model (SM) for prediction of statistical characteristics of steam explosion impulses in Nordic BWRs. The TEXAS-V code was used as the Full Model (FM) for the calculation of explosion impulses. The surrogate model was developed using artificial neural networks (ANNs) and the database of FM solutions. Statistical analysis was employed in order to treat chaotic response of steam explosion impulse to variations in the triggering time. Details of the FM and SM implementation and their verification are discussed in the paper.

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)

Modelling and verification of once-through subcritical heat recovery steam generator

International Nuclear Information System (INIS)

Lee, Chae Soo; Choi, Young Jun; Kim, Hyun Gee; Yang, Ok Chul; Chong Chae Hon

2004-01-01

The once-through heat recovery steam generator is ideally matched to very high temperature and pressure, well into the supercritical range. Moreover this type of boiler is structurally simpler than drum type boiler. In drum type boiler, each tube play a well-defined role: water preheating, vaporization, superheating. Empirical equations are available to predict the average heat transfer coefficient for each regime. For once-through heat recovery steam generator, this is no more the case and mathematical models have to be adapted to account for the disappearance of drum type economizer, boiler, superheater. General equations have to be used for each tube of boiler, and actual heat transfer condition in each tube has to be identified

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.

Electric dipole moments of charged leptons with sterile fermions

International Nuclear Information System (INIS)

Abada, Asmaa; Toma, Takashi

2016-01-01

We address the impact of sterile fermions on charged lepton electric dipole moments. Any experimental signal of these observables calls for scenarios of physics beyond the Standard Model providing new sources of CP violation. In this work, we consider a minimal extension of the Standard Model via the addition of sterile fermions which mix with active neutrinos and we derive the corresponding analytical expressions for the electric dipole moments of charged leptons at two-loop order. Our study reveals that, in order to have a non-vanishing contribution in this framework, the minimal extension necessitates the addition of at least 2 sterile fermion states to the Standard Model field content. Our conclusion is that sterile neutrinos can give significant contributions to the charged lepton electric dipole moments, some of them lying within present and future experimental sensitivity if the masses of the non-degenerate sterile states are both above the electroweak scale. The Majorana nature of neutrinos is also important in order to allow for significative contributions to the charged lepton electric dipole moments. In our analysis we impose all available experimental and observational constraints on sterile neutrinos and we further discuss the prospect of probing this scenario at low and high energy experiments.

Electric dipole moments of charged leptons with sterile fermions

Energy Technology Data Exchange (ETDEWEB)

Abada, Asmaa; Toma, Takashi [Laboratoire de Physique Théorique, CNRS, University Paris-Sud, Université Paris-Saclay, 91405 Orsay (France)

2016-02-26

We address the impact of sterile fermions on charged lepton electric dipole moments. Any experimental signal of these observables calls for scenarios of physics beyond the Standard Model providing new sources of CP violation. In this work, we consider a minimal extension of the Standard Model via the addition of sterile fermions which mix with active neutrinos and we derive the corresponding analytical expressions for the electric dipole moments of charged leptons at two-loop order. Our study reveals that, in order to have a non-vanishing contribution in this framework, the minimal extension necessitates the addition of at least 2 sterile fermion states to the Standard Model field content. Our conclusion is that sterile neutrinos can give significant contributions to the charged lepton electric dipole moments, some of them lying within present and future experimental sensitivity if the masses of the non-degenerate sterile states are both above the electroweak scale. The Majorana nature of neutrinos is also important in order to allow for significative contributions to the charged lepton electric dipole moments. In our analysis we impose all available experimental and observational constraints on sterile neutrinos and we further discuss the prospect of probing this scenario at low and high energy experiments.

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.

Numerical simulation in steam injection process by a mechanistic approach

Energy Technology Data Exchange (ETDEWEB)

De Souza, J.C.Jr.; Campos, W.; Lopes, D.; Moura, L.S.S. [Petrobras, Rio de Janeiro (Brazil)

2008-10-15

Steam injection is a common thermal recovery method used in very viscous oil reservoirs. The method involves the injection of heat to reduce viscosity and mobilize oil. A steam generation and injection system consists primarily of a steam source, distribution lines, injection wells and a discarding tank. In order to optimize injection and improve the oil recovery factor, one must determine the parameters of steam flow such as pressure, temperature and steam quality. This study focused on developing a unified mathematical model by means of a mechanistic approach for two-phase steam flow in pipelines and wells. The hydrodynamic and heat transfer mechanistic model was implemented in a computer simulator to model the parameters of steam injection while trying to avoid the use of empirical correlations. A marching algorithm was used to determine the distribution of pressure and temperature along the pipelines and wellbores. The mathematical model for steam flow in injection systems, developed by a mechanistic approach (VapMec) performed well when the simulated values of pressures and temperatures were compared with the values measured during field tests. The newly developed VapMec model was incorporated in the LinVap-3 simulator that constitutes an engineering supporting tool for steam injection wells operated by Petrobras. 23 refs., 7 tabs., 6 figs.

Dynamic Modeling of Steam Condenser and Design of PI Controller Based on Grey Wolf Optimizer

Directory of Open Access Journals (Sweden)

Shu-Xia Li

2015-01-01

Full Text Available Shell-and-tube condenser is a heat exchanger for cooling steam with high temperature and pressure, which is one of the main kinds of heat exchange equipment in thermal, nuclear, and marine power plant. Based on the lumped parameter modeling method, the dynamic mathematical model of the simplified steam condenser is established. Then, the pressure PI control system of steam condenser based on the Matlab/Simulink simulation platform is designed. In order to obtain better performance, a new metaheuristic intelligent algorithm, grey wolf optimizer (GWO, is used to realize the fine-tuning of PI controller parameters. On the other hand, the Z-N engineering tuning method, genetic algorithm, and particle swarm algorithm are adopted for tuning PI controller parameters and compared with GWO algorithm. Simulation results show that GWO algorithm has better control performance than other four algorithms.

Sterile Neutrino Search with MINOS

International Nuclear Information System (INIS)

Devan, Alena V.

2015-01-01

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, Δm 2 . 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, Δm s 2 ~ 1 eV 2 . The results of the 2013 sterile neutrino search are presented here.

Computational Fluid Dynamics Modeling of Steam Condensation on Nuclear Containment Wall Surfaces Based on Semiempirical Generalized Correlations

Directory of Open Access Journals (Sweden)

Pavan K. Sharma

2012-01-01

Full Text Available In water-cooled nuclear power reactors, significant quantities of steam and hydrogen could be produced within the primary containment following the postulated design basis accidents (DBA or beyond design basis accidents (BDBA. For accurate calculation of the temperature/pressure rise and hydrogen transport calculation in nuclear reactor containment due to such scenarios, wall condensation heat transfer coefficient (HTC is used. In the present work, the adaptation of a commercial CFD code with the implementation of models for steam condensation on wall surfaces in presence of noncondensable gases is explained. Steam condensation has been modeled using the empirical average HTC, which was originally developed to be used for “lumped-parameter” (volume-averaged modeling of steam condensation in the presence of noncondensable gases. The present paper suggests a generalized HTC based on curve fitting of most of the reported semiempirical condensation models, which are valid for specific wall conditions. The present methodology has been validated against limited reported experimental data from the COPAIN experimental facility. This is the first step towards the CFD-based generalized analysis procedure for condensation modeling applicable for containment wall surfaces that is being evolved further for specific wall surfaces within the multicompartment containment atmosphere.

Steam generator tube integrity program

International Nuclear Information System (INIS)

Dierks, D.R.; Shack, W.J.; Muscara, J.

1996-01-01

A new research program on steam generator tubing degradation is being sponsored by the U.S. Nuclear Regulatory Commission (NRC) at Argonne National Laboratory. This program is intended to support a performance-based steam generator tube integrity rule. Critical areas addressed by the program include evaluation of the processes used for the in-service inspection of steam generator tubes and recommendations for improving the reliability and accuracy of inspections; validation and improvement of correlations for evaluating integrity and leakage of degraded steam generator tubes, and validation and improvement of correlations and models for predicting degradation in steam generator tubes as aging occurs. The studies will focus on mill-annealed Alloy 600 tubing, however, tests will also be performed on replacement materials such as thermally-treated Alloy 600 or 690. An overview of the technical work planned for the program is given

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

Sterilization of instruments in solar ovens

Energy Technology Data Exchange (ETDEWEB)

Fjendbo Joergensen, A. [Odense Univ. Hospital, Dept. of Infectious Diseases, Odense (Denmark); Noehr, K. [Odense Technical College, Dept. of Metal, Odense (Denmark); Boisen, F. [The Danish Veterinary and Food Administration Funen, Dept. of Microbiology, Odense (Denmark)

2000-07-01

The sterilization of instruments in rural health clinics in less developed countries is an increasing problem because chemical methods can no longer be recommended and wood fuel is becoming more and more scarce. Thus, it seemed obvious to try to utilize solar energy for sterilization purposes. A solar oven was designed and manufactured using local materials and simple tools. The solar oven was tested by physical, chemical, and microbiological methods. A mathematical model for the sterilization effect was developed and programmed into a microprocessor that was connected to a thermocouple. The microprocessor switches on a green light when the sterilization is completed. After successful testing, the oven was built into the west-facing wall of a rural health clinic and used daily for sterilization. The oven was able to generate temperatures above 180 deg. C. On all days with direct sunlight the oven fulfilled the international recommendations for hot air sterilization because no growth could be detected from any of the test bacteria spores. The chemical indicators Brownes tubes types 3 and 5 also changed colours. The solar oven was easy to use for the clinic staff, but during the seasons with low sun position (in Tanzania, December and June) it was difficult to achieve a high enough temperature for sterilization. Therefore, if the method is to be used throughout the year the oven must be moved to collect the sun's rays from several directions, or the clinic must have more than one solar oven facing in different directions. We conclude that the solar oven is a realistic method for sterilization of instruments. (au)

Genomic networks of hybrid sterility.

Science.gov (United States)

Turner, Leslie M; White, Michael A; Tautz, Diethard; Payseur, Bret A

2014-02-01

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 applicable in a broad

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.

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.

Radiation sterilization of livestock feeds

International Nuclear Information System (INIS)

Kawashima, Koji

1984-01-01

The radiation sterilization of livestock feeds is not much used presently because the process is not known well, and the cost is relatively high. However, its effect of sterilization is absolute, the radiation-sterilized feeds are safe in both nutrition and toxicity, and do not affect the appetite of livestocks, and the radiation energy required is small. In the future, as in the sterilization of medical supplies, feed radiation sterilization plants should be established, to stabilize livestock industry and to contribute to the health control of experimental animals. The following matters are described: radiation, comparison between radiation sterilization and other sterilization methods, the practice of feed radiation sterilization, the adverse effects of radiation sterilization, economic aspect, and the situation of feed radiation sterilization in various countries. (Mori, K.)

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 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 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.

The genetics of hybrid male sterility between the allopatric species pair Drosophila persimilis and D. pseudoobscura bogotana: dominant sterility alleles in collinear autosomal regions.

Science.gov (United States)

Chang, Audrey S; Noor, Mohamed A F

2007-05-01

F(1) hybrid male sterility is thought to result from interactions between loci on the X chromosome and dominant-acting loci on the autosomes. While X-linked loci that contribute to hybrid male sterility have been precisely localized in many animal taxa, their dominant autosomal interactors have been more difficult to localize precisely and/or have been shown to be of relatively smaller effect. Here, we identified and mapped at least four dominant autosomal factors contributing to hybrid male sterility in the allopatric species pair Drosophila persimilis and D. pseudoobscura bogotana. Using these results, we tested predictions of reduced recombination models of speciation. Consistent with these models, three of the four QTL associated with hybrid male sterility occur in collinear (uninverted) regions of these genomes. Furthermore, these QTL do not contribute significantly to hybrid male sterility in crosses between the sympatric species D. persimilis and D. pseudoobscura pseudoobscura. The autosomal loci identified in this study provide the basis for introgression mapping and, ultimately, for molecular cloning of interacting genes that contribute to F(1) hybrid sterility.

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

A spatial model with pulsed releases to compare strategies for the sterile insect technique applied to the mosquito Aedes aegypti.

Science.gov (United States)

Oléron Evans, Thomas P; Bishop, Steven R

2014-08-01

We present a simple mathematical model to replicate the key features of the sterile insect technique (SIT) for controlling pest species, with particular reference to the mosquito Aedes aegypti, the main vector of dengue fever. The model differs from the majority of those studied previously in that it is simultaneously spatially explicit and involves pulsed, rather than continuous, sterile insect releases. The spatially uniform equilibria of the model are identified and analysed. Simulations are performed to analyse the impact of varying the number of release sites, the interval between pulsed releases and the overall volume of sterile insect releases on the effectiveness of SIT programmes. Results show that, given a fixed volume of available sterile insects, increasing the number of release sites and the frequency of releases increases the effectiveness of SIT programmes. It is also observed that programmes may become completely ineffective if the interval between pulsed releases is greater that a certain threshold value and that, beyond a certain point, increasing the overall volume of sterile insects released does not improve the effectiveness of SIT. It is also noted that insect dispersal drives a rapid recolonisation of areas in which the species has been eradicated and we argue that understanding the density dependent mortality of released insects is necessary to develop efficient, cost-effective SIT programmes. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Inherited sterility in insects

International Nuclear Information System (INIS)

Carpenter, J.E.; Marec, F.; Bloem, S.

2005-01-01

The unique genetic phenomena responsible for inherited sterility (IS) in Lepidoptera and some other arthropods, as compared with full sterility, provide advantages for pest control. Lepidopteran females are usually more sensitive to radiation than males of the same species. This allows the radiation dose to be adjusted to suit programme requirements. When partially sterile males mate with wild females, the radiation-induced deleterious effects are inherited by the F 1 generation. As a result, egg hatch is reduced and the resulting offspring are both highly sterile and predominately male. Compared with the high radiation required to achieve full sterility in Lepidoptera, the lower dose of radiation used to induce F 1 sterility increases the quality and competitiveness of the released insects as measured by improved dispersal after release, increased mating ability, and superior sperm competition. F 1 sterile progeny produced in the field enhance the efficacy of released partially sterile males, and improve compatibility with other pest control strategies. In addition, F 1 sterile progeny can be used to increase the production of natural enemies, and to study the potential host and geographical ranges of exotic lepidopteran pests. (author)

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)

Steam turbine cycle

International Nuclear Information System (INIS)

Okuzumi, Naoaki.

1994-01-01

In a steam turbine cycle, steams exhausted from the turbine are extracted, and they are connected to a steam sucking pipe of a steam injector, and a discharge pipe of the steam injector is connected to an inlet of a water turbine. High pressure discharge water is obtained from low pressure steams by utilizing a pressurizing performance of the steam injector and the water turbine is rotated by the high pressure water to generate electric power. This recover and reutilize discharged heat of the steam turbine effectively, thereby enabling to improve heat efficiency of the steam turbine cycle. (T.M.)

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.

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.)

Sterilization of health care products - Chemical indicators - Part 5: Class 2 indicators for Bowie and Dick-type air removal tests. 2. ed.

International Nuclear Information System (INIS)

2007-01-01

The air removal test is used to evaluate the efficacy of air removal during the pre-vacuum phase of a prevacuum sterilization cycle or during the pulsing stage of positive pulsing cycles if non-condensable gases were present in the steam. Retention of air due to an inefficient air removal stage or the presence of an air leak or non-condensable gases during the air removal stage are circumstances which can lead to failure of the test. This part of ISO 11140 describes the requirements for Class 2 indicators for Bowie and Dick-type air removal test sheets and packs. For a description of the classes of chemical indicators, see ISO 11140-1. The difference between the steam penetration test (ISO 11140-3 and ISO 11140-4) and the air removal test (ISO 11140-5) is described in the chemical indicator guidance document (ISO 15882). This part of ISO 11140 specifies the requirements for Class 2 indicators for Bowie and Dick-type air removal tests used to evaluate the effectiveness of air removal during the pre-vacuum phase of pre-vacuum steam sterilization cycles. Additionally, this part of ISO 11140 includes test methods and equipment used to meet these performance requirements. The paper provides information on scope, normative references, terms and definitions, general requirements, indicator system, its format and performance, indicator, its format and performance, packaging and labelling, quality assurance and sampling conditioning. 7 annexes report on the determination of the degree of contrast between the colour of the substrate and the indicator agent, the method of determining uniform colour change on exposure to saturated steam, the method of determining indicator colour change on exposure to dry heat, the method of determining transfer of indicator agent to standard test pack, standard test pack, the method of determining non-uniform colour change on exposure to a standard fault condition, and the steam exposure apparatus. Finally a bibliography is provided

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.

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, m_s² ~ 1 eV². The results of the 2013 sterile neutrino search are presented here.

A Receding Horizon Controller for the Steam Generator Water Level

International Nuclear Information System (INIS)

Na, Man Gyun; Lee, Yoon Joon

2003-01-01

In this work, the receding horizon control method was used to control the water level of nuclear steam generators and applied to two linear models and also a nonlinear model of steam generators. A receding horizon control method is to solve an optimization problem for finite future steps at current time and to implement the first optimal control input as the current control input. The procedure is then repeated at each subsequent instant. The dynamics of steam generators is very different according to power levels. The receding horizon controller is designed by using a reduced linear steam generator model fixed over a certain power range and applied to a Westinghouse-type (U-tube recirculating type) nuclear steam generator. The proposed controller designed at a fixed power level shows good performance for any other power level within this power range. The steam generator shows actually nonlinear characteristics. Therefore, the proposed algorithm is implemented for a nonlinear model of the nuclear steam generator to verify its real performance and also shows good responses

Transient population dynamics of mosquitoes during sterile male releases: modelling mating behaviour and perturbations of life history parameters.

Directory of Open Access Journals (Sweden)

Christopher M Stone

Full Text Available The release of genetically-modified or sterile male mosquitoes offers a promising form of mosquito-transmitted pathogen control, but the insights derived from our understanding of male mosquito behaviour have not fully been incorporated into the design of such genetic control or sterile-male release methods. The importance of aspects of male life history and mating behaviour for sterile-male release programmes were investigated by projecting a stage-structured matrix model over time. An elasticity analysis of transient dynamics during sterile-male releases was performed to provide insight on which vector control methods are likely to be most synergistic. The results suggest that high mating competitiveness and mortality costs of released males are required before the sterile-release method becomes ineffective. Additionally, if released males suffer a mortality cost, older males should be released due to their increased mating capacity. If released males are of a homogenous size and size-assortative mating occurs in nature, this can lead to an increase in the abundance of large females and reduce the efficacy of the population-suppression effort. At a high level of size-assortative mating, the disease transmission potential of the vector population increases due to male releases, arguing for the release of a heterogeneously-sized male population. The female population was most sensitive to perturbations of density-dependent components of larval mortality and female survivorship and fecundity. These findings suggest source reduction might be a particularly effective complement to mosquito control based on the sterile insect technique (SIT. In order for SIT to realize its potential as a key component of an integrated vector-management strategy to control mosquito-transmitted pathogens, programme design of sterile-male release programmes must account for the ecology, behaviour and life history of mosquitoes. The model used here takes a step in this

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

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

[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.

Modeling and simulation of once-through steam generator of casing pipes

International Nuclear Information System (INIS)

Niu Guanglin; Fu Mingyu; Yan Changqi; Nan Jingfu

2009-01-01

Adynamic model about the double casing pipes structure of double-face heat transfer is accepted in new type once-through steam generator (OTSG) is established. The model,which can be applied to any steady and dynamic conditions of OSTG in different flowing and heat transferring characteristic,is developed. It provides the bases for the design and operation of control system, analysis and treatment of abnormal conditions and faults, and development of operation rules. (authors)

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

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

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.

Sterile neutrinos with eV masses in cosmology — How disfavoured exactly?

International Nuclear Information System (INIS)

Hamann, Jan; Hannestad, Steen; Raffelt, Georg G.; Wong, Yvonne Y.Y.

2011-01-01

We study cosmological models that contain sterile neutrinos with eV-range masses as suggested by reactor and short-baseline oscillation data. We confront these models with both precision cosmological data (probing the CMB decoupling epoch) and light-element abundances (probing the BBN epoch). In the minimal ΛCDM model, such sterile neutrinos are strongly disfavoured by current data because they contribute too much hot dark matter. However, if the cosmological framework is extended to include also additional relativistic degrees of freedom beyond the three standard neutrinos and the putative sterile neutrinos, then the hot dark matter constraint on the sterile states is considerably relaxed. A further improvement is achieved by allowing a dark energy equation of state parameter w e degeneracy. Any model containing eV-mass sterile neutrinos implies also strong modifications of other cosmological parameters. Notably, the inferred cold dark matter density can shift up by 20–75% relative to the standard ΛCDM value

Modeling local chemistry in PWR steam generator crevices

International Nuclear Information System (INIS)

Millett, P.J.

1997-01-01

Over the past two decades steam generator corrosion damage has been a major cost impact to PWR owners. Crevices and occluded regions create thermal-hydraulic conditions where aggressive impurities can become highly concentrated, promoting localized corrosion of the tubing and support structure materials. The type of corrosion varies depending on the local conditions, with stress corrosion cracking being the phenomenon of most current concern. A major goal of the EPRI research in this area has been to develop models of the concentration process and resulting crevice chemistry conditions. These models may then be used to predict crevice chemistry based on knowledge of bulk chemistry, thereby allowing the operator to control corrosion damage. Rigorous deterministic models have not yet been developed; however, empirical approaches have shown promise and are reflected in current versions of the industry-developed secondary water chemistry guidelines

Condensate polisher application for PWR steam generator corrosion control

International Nuclear Information System (INIS)

Sawochka, S.G.; Leibovitz, J.; Siegwarth, D.P.; Pearl, W.L.

1981-01-01

The evolution of corrosion attack modes particularly in recirculating U-tube PWR steam generators has dictated a thorough review of the advantages and disadvantages of condensate polishing. Analytical modeling techniques to qualitatively predict crevice chemistry variations resulting from steam generator bulk water variations have allowed valuable insights to be developed. Modeling results complemented by steam generator and laboratory corrosion data will be employed to set condensate demineralizer effluent specifications consistent with control of steam generator corrosion. Laboratory and plant studies are being performed to demonstrate achievability of necessary effluent specifications. (author)

Reversibility of female sterilization.

Science.gov (United States)

Siegler, A M; Hulka, J; Peretz, A

1985-04-01

The discussion considers the current status of reversibility of sterilization in the US and describes clinical and experimental efforts for developing techniques designed for reversibility. It focuses on regret following sterilization, reversal potential of current sterilization techniques, patient selection, current reversal techniques, results of sterilization procedures, experimental approaches to reversal of current techniques of sterilization, and sterilization procedures devised for reversibility, in humans and in animals. Request is the 1st stage of reversal, but a request for sterilization reversal (SR) does not always mean regret for a decision made at the time. Frequently it is a wish to restore fertility because life circumstances have changed after a sterilization that was ppropriate at the time it was performed. Schwyhart and Kutner reviewed 22 studies published between 1949-69 in which they found that the percentage of patients regretting the procedure ranged from 1.3-15%. Requests for reversal remain low in most countries, but if sterilization becomes a more popular method of contraception, requests will also increase. The ideal operation considered as a reversaible method of sterilization should include an easy, reliable outpatient method of tubal occlusion with miniml risk or patient discomfort that subsequently could be reversed without the need for a major surgical intervention. Endoscopic methods have progressed toward the 1st objective. A recent search of the literature uncovered few series of SR of more than 50 cases. The 767 operations found were analyzed with regard to pregnancy outcome. The precent of live births varied from 74-78.8%, and the occurance of tubal pregnancies ranged from 1.7-6.5%. All of the confounding variables in patient selection and small numbers of reported procedures preclude any conclusion about the different techniques or the number of operations that give a surgeon a level of expertise. Few authors classify their

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.

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)

1998-12-31

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.

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}.

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

Radiation sterilization of medical products

International Nuclear Information System (INIS)

Khurshid, S.J.; Hussain, A.M.

1989-01-01

Radiation sterilization is the best method of sterilization, essentially for single use medical and surgical products. Pakistan has established a commercial gamma irradiation plant for this purpose. This article overviews the advantages and benefits of radiation sterilization to stimulate the interest of industrialists and the users in this technology. This technology can give a better medical care in the country and the growing demand can only be met by bulk sterilization. The radiation sterilized medical products can also compete well with the products sterilized by other methods in the international market, gamma sterilization is accepted internationally and if adopted it can boost our export of medical products. (author)

Effect of steam pretreatment on oil palm empty fruit bunch for the production of sugars

International Nuclear Information System (INIS)

Shamsudin, Saleha; Md Shah, Umi Kalsom; Zainudin, Huzairi; Abd-Aziz, Suraini; Mustapa Kamal, Siti Mazlina; Shirai, Yoshihito; Hassan, Mohd Ali

2012-01-01

Lignocellulose into fuel ethanol is the most feasible conversion route strategy in terms of sustainability. Oil palm empty fruit bunch (EFB) generated from palm oil production is a huge source of cellulosic material and represents a cheap renewable feedstock which awaits further commercial exploitation. The purpose of this study was to investigate the feasibility of using steam at 0.28 MPa and 140 °C generated from the palm oil mill boiler as a pretreatment to enhance the digestibility of EFB for sugars production. The effects of steam pretreatment or autohydrolysis on chemical composition changes, polysaccharide conversion, sugar production and morphology alterations of four different types of EFB namely fresh EFB (EFB1), sterilized EFB (EFB2), shredded EFB (EFB3) and ground EFB (EFB4) were evaluated. In this study, the effects of steam pretreatment showed major alterations in the morphology of EFB as observed under the scanning electron microscope. Steam pretreated EFB2 was found to have the highest total conversion of 30% to sugars with 209 g kg −1 EFB. This production was 10.5 fold higher than for EFB1 and 1.6 fold and 1.7 fold higher than EFB3 and EFB4, respectively. The results suggested that pretreatment of EFB by autohydrolysis using steam from the mill boiler could be considered as being a suitable pretreatment process for the production of sugars. These sugars can be utilized as potential substrates for the production of various products such as fuel ethanol. -- Highlights: ► We investigate the feasibility of steam pretreatment to enhance digestibility of EFB. ► Steam pretreatment increased sugars to 3.4 fold and caused major alteration in EFB morphology under SEM. ► Autohydrolysis which does not require the addition of chemicals is an attractive pretreatment approach to EFB.

Completion of a simulation model for calculation of static and dynamic behaviour of steam generators and its use for a pilot steam generator

Energy Technology Data Exchange (ETDEWEB)

Seybold, M

1979-07-20

In the present paper, first of all the model concept reported in detail by Schittke is applied to the steady-state predictive calculation of an arbitrarily nested steam generator based on the design data and empirical values on heat discharge and heat transfer. The dynamics of the system are precalculated on the basis of the known steady-state behaviour and with the construction data, that is without experimental identification, according to the Schittke concept. The object for the calculation is a steam generator with once-through forced flow (VDE) which was put at the disposal of the Institute for Process Engineering and Steamboiler Studies. Data for the computer programs were taken only from the construction documents (geometries, nesting etc.) or from design data (thermic parameters). Parallel with the program preparation and the calculation measurements on the experimental plant were planned, adaptations and tests were carried out. The correctness of precalculating a steam generator could then be checked with the experimental plant and by comparison with the results of the measurements.

CATHENA analysis of CANDU 6 steam generators for steam main break at a remote location

Energy Technology Data Exchange (ETDEWEB)

Liu, T. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

2009-07-01

CATHENA (Canadian Algorithm for THErmalhydraulic Network Analysis) is a nonequilibrium, two-phase, two fluid network analysis code that has been in use for over two decades by various groups in Canada and around the world. It is the primary Thermalhydraulics network analysis tool used by Atomic Energy Canada Ltd. (AECL) in the design, safety and licensing analysis of power and research reactors as well as test facilities. In the thermalhydraulic model, the liquid and vapor phases may have different pressures, velocities, and temperatures. The objective of the present paper is to present the detailed modeling of a CANDU 6 Steam Generator (SG) using the transient, thermalhydraulics network code CATHENA. The model represents the secondary side, primary side and the main steam system including the main steam line up to the assumed break location. The present model is designed such that the transient pressure drops across Tube Support Plates (TSP) could be extracted. The resistances of degraded/fouled TSPs were modeled by using the increased/reduced flow area of the TSPs. CATHENA then calculates the flow resistance in two-phase flow based on the area contraction/expansion at the TSPs. Three sets of simulations were performed; one with the degraded steam generator data provided by the utility users, and the other two with waterlanced (cleaned with high pressure water jet) TSPs. One run assumed the flow area increased by 25 percent, the other run assumed the flow area increased by 50 percent. on the hot side of the SG. No significant changes in the break discharge rates were observed between the runs. However, the steam generator downcomer flow for the waterlanced case did not reverse during the blowdown as was calculated for the degraded case. As expected, the pressure drop across the TSPs was decreased in the waterlanced cases comparing with degraded cases. The CATHENA simulation provides estimates of the velocity, density, and quality in the tube bundle as well as

Steam turbine installations

International Nuclear Information System (INIS)

Bainbridge, A.

1976-01-01

The object of the arrangement described is to enable raising steam for driving steam turbines in a way suited to operating with liquid metals, such as Na, as heat transfer medium. A preheated water feed, in heat transfer relationship with the liquid metals, is passed through evaporator and superheater stages, and the superheated steam is supplied to the highest pressure stage of the steam turbine arrangement. Steam extracted intermediate the evaporator and superheater stages is employed to provide reheat for the lower pressure stage of the steam turbine. Only a major portion of the preheated water feed may be evaporated and this portion separated and supplied to the superheater stage. The feature of 'steam to steam' reheat avoids a second liquid metal heat transfer and hence represents a simplification. It also reduces the hazard associated with possible steam-liquid metal contact. (U.K.)

Modified Baryonic Dynamics: two-component cosmological simulations with light sterile neutrinos

Energy Technology Data Exchange (ETDEWEB)

Angus, G.W.; Gentile, G. [Department of Physics and Astrophysics, Vrije Universiteit Brussel, Pleinlaan 2, Brussels, 1050 Belgium (Belgium); Diaferio, A. [Dipartimento di Fisica, Università di Torino, Via P. Giuria 1, Torino, I-10125 Italy (Italy); Famaey, B. [Observatoire astronomique de Strasbourg, CNRS UMR 7550, Université de Strasbourg, 11 rue de l' Université, Strasbourg, F-67000 France (France); Heyden, K.J. van der, E-mail: garry.angus@vub.ac.be, E-mail: diaferio@ph.unito.it, E-mail: benoit.famaey@astro.unistra.fr, E-mail: gianfranco.gentile@ugent.be, E-mail: heyden@ast.uct.ac.za [Astrophysics, Cosmology and Gravity Centre, Dept. of Astronomy, University of Cape Town, Private Bag X3, Rondebosch, 7701 South Africa (South Africa)

2014-10-01

In this article we continue to test cosmological models centred on Modified Newtonian Dynamics (MOND) with light sterile neutrinos, which could in principle be a way to solve the fine-tuning problems of the standard model on galaxy scales while preserving successful predictions on larger scales. Due to previous failures of the simple MOND cosmological model, here we test a speculative model where the modified gravitational field is produced only by the baryons and the sterile neutrinos produce a purely Newtonian field (hence Modified Baryonic Dynamics). We use two-component cosmological simulations to separate the baryonic N-body particles from the sterile neutrino ones. The premise is to attenuate the over-production of massive galaxy cluster halos which were prevalent in the original MOND plus light sterile neutrinos scenario. Theoretical issues with such a formulation notwithstanding, the Modified Baryonic Dynamics model fails to produce the correct amplitude for the galaxy cluster mass function for any reasonable value of the primordial power spectrum normalisation.

Methods of sterilization and monitoring of sterilization across selected dental practices in karachi, pakistan

International Nuclear Information System (INIS)

Ahmed, H.

2015-01-01

To assess methods of sterilization in dental practices in Karachi and secondly to investigate methods of monitoring sterilization in dental practices in Karachi, Pakistan. Study Design: Cross-sectional, descriptive study. Place and Duration of Study: Dental colleges, hospitals and private clinics of Karachi, Pakistan, from January to March 2013. Methodology: A total of 251 questionnaires were obtained. Descriptive statistics were computed and differences between groups were assessed through chi-square test using Statistical Package for the Social Sciences (SPSS) version 16.0. P-value < 0.05 was taken as statistically significant. Results: Autoclave, used by 155 (61.8%) dentists was the most common method of sterilization followed by more than one method, 65 (25.9%); dry heat, 24 (9.6%); and cold sterilization, 7 (2.8%). Majority of dentists, 126 (50.1%), never monitored sterilization and those who did monitored mostly monthly. Statistically significant difference was found amongst the three groups of dentists monitoring sterilization (p=0.09) and methods of sterilization (p < 0.01). Conclusion: Statistically significant difference was found in infection control practices of specialists, postgraduate trainees and general dentists regarding method of monitoring sterilization with majority of dentists never monitoring sterilization. (author)

Radiosterilization and gas sterilization

International Nuclear Information System (INIS)

Schultz, H.A.; Gruenewald, T.

1987-01-01

The book presents a survey of the principles of cold sterilization by radiation or gas, and also of the problems involved. The reader who has to do with sterilization of some kind or other, as e.g. sterilization of medicaments, medical supplies, medical device, drugs, grafts, or food, will find comprehensive information on the various available methods and their effects, as well as on monitoring procedures and techniques, together with proposals for efficient documentation and validation of partial sterilization processes. The introduction summarizes the potentials of sterilization by radiation, and the subsequent by radiation, and the subsequent chapters explain the specific applicabilities of radiosterilization along with the most important criteria for evaluating the sterilizing efficiency. The information on the legal situation and requirements takes into account the second amendment of the Medical Preparations Act. With 38 figs., 14 tabs [de

A White Paper on keV sterile neutrino Dark Matter

Energy Technology Data Exchange (ETDEWEB)

Adhikari, R. [Centre for Theoretical Physics, Jamia Millia Islamia (Central University), New Delhi-110025 (India); Agostini, M. [Gran Sasso Science Institute (INFN), L' Aquila (Italy); Ky, N. Anh [Institute of physics, Vietnam academy of science and technology, 10 Dao Tan, Ba Dinh, Hanoi (Viet Nam); Araki, T. [Department of physics, Saitama University, Shimo-Okubo 255, 338-8570 Saitama Sakura-ku (Japan); Archidiacono, M. [Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Bahr, M. [University of California, Santa Barbara (United States); Baur, J. [Commissariat à l' énergie atomique et aux énergies alternatives, Centre de Saclay, DSM/IRFU, 91191 Gif-sur-Yvette (France); Behrens, J. [Westfälische Wilhelms Universität Münster, Institut für Kernphysik, Wilhelm Klemm-Str.9, D-48149 Münster (Germany); Bezrukov, F. [University of Connecticut (United States); Dev, P.S. Bhupal [Consortium for Fundamental Physics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Borah, D. [Department of Physics, Indian Institute of Technology Guwahati, Assam-781039 (India); Boyarsky, A. [Universiteit Leiden - Instituut Lorentz for Theoretical Physics, P.O. Box 9506, NL-2300 RA Leiden, Netherlands (Netherlands); De Gouvea, A. [Northwestern University (United States); Pires, C.A. de S. [Departamento de Física, UFPB, Caixa Postal 5008, 58051-970, João Pessoa, PB (Brazil); De Vega, H.J. [CNRS LPTHE UPMC Univ P. et M. Curie Paris VI (France); and others

2017-01-01

We present a comprehensive review of keV-scale sterile neutrino Dark Matter, collecting views and insights from all disciplines involved—cosmology, astrophysics, nuclear, and particle physics—in each case viewed from both theoretical and experimental/observational perspectives. After reviewing the role of active neutrinos in particle physics, astrophysics, and cosmology, we focus on sterile neutrinos in the context of the Dark Matter puzzle. Here, we first review the physics motivation for sterile neutrino Dark Matter, based on challenges and tensions in purely cold Dark Matter scenarios. We then round out the discussion by critically summarizing all known constraints on sterile neutrino Dark Matter arising from astrophysical observations, laboratory experiments, and theoretical considerations. In this context, we provide a balanced discourse on the possibly positive signal from X-ray observations. Another focus of the paper concerns the construction of particle physics models, aiming to explain how sterile neutrinos of keV-scale masses could arise in concrete settings beyond the Standard Model of elementary particle physics. The paper ends with an extensive review of current and future astrophysical and laboratory searches, highlighting new ideas and their experimental challenges, as well as future perspectives for the discovery of sterile neutrinos.

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.

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)

1998-12-31

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)

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)

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)

Steam Line Break Analysis in CAREM-25 Reactor

International Nuclear Information System (INIS)

Zanocco, Pablo; Gimenez, Marcelo; Vertullo, Alicia; Garcia, A; Schlamp, Miguel

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

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

Esterilização em Ortodontia: eficácia do esterilizador com esferas de vidro Sterilization in Orthodontics: effectiveness of glass bead sterilizers

Directory of Open Access Journals (Sweden)

Sônia Rodrigues Dutra

2008-08-01

Full Text Available OBJETIVO: avaliar a efetividade do esterilizador com esferas de vidro Steri® 350, quanto ao controle de infecção das partes ativas dos alicates ortodônticos. METODOLOGIA: foram utilizados nove alicates ortodônticos, previamente esterilizados em autoclave à temperatura de 121ºC, durante 20 minutos. Posteriormente, as partes ativas dos alicates foram contaminadas com Bacillus stearothermophilus. Logo após, as pontas dos alicates foram colocadas no Steri® 350, durante os períodos de 3, 5, 10, 15, 20, 30 e 40 segundos, em temperatura de 255ºC, para avaliar a eficácia da esterilização. RESULTADOS E CONCLUSÕES: o esterilizador com esferas de vidro mostrou-se eficaz no controle do crescimento de Bacillus stearothermophilus nas partes ativas dos alicates ortodônticos, a partir de 10 segundos de exposição à temperatura de 255ºC.AIM: The aim of this research was to evaluate the efficiency of Steri® 350glass bead sterilizer, on the infection control of the active part of the orthodontic pliers. METHODS: Nine orthodontic pliers were sterilized in the steam autoclave at 121ºC in 20 minutes and subsequently the active part of each plier was dipped in a culture for Bacillus stearothermophilus. Later, the active part of each plier was putted into the Steri® 350 in the following periods: 3, 5, 10, 15, 20, 30, and 40 seconds at 255ºC to evaluate the efficiency of this method in the infection control. RESULTS AND CONCLUSIONS: This sterilization method has been effective to control the presence of Bacillus stearothermophilus on the active part of orthodontic pliers at 255ºC in 10 seconds.

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).

Male and female sterility in Zambia

Directory of Open Access Journals (Sweden)

Athena Pantazis

2014-02-01

Full Text Available Background: Population measures of sterility are traditionally constructed for women, despite fertility and sterility being conditions of the couple. Estimates of male sterility provide insight into population-level sterility, and complement estimates based solely on women. Objective: This study seeks to estimate male sterility for the Gwembe Tonga of Zambia using male birth histories collected by the Gwembe Tonga Research Project from 1957 to 1995, while providing context by estimating female sterility for the Gwembe Tonga, as well as female sterility in all of Zambia, from Zambian DHS data (1992, 1997, 2001-02, and 2007. Methods: Sterility is measured using the Larson-Menken subsequently infertile indicator. Estimates are produced using discrete time event history analysis. Results: The odds of sterility were higher for women than men, though women's odds of sterility were only 1.5 times that of men's in the middle reproductive years. The odds of sterility increased steadily with age for both men and women, and across all datasets. However, women's sterility increased much more sharply with age than men's did, and women's odds of sterility were higher than men's at all reproductive ages.

Gene, protein, and network of male sterility in rice

OpenAIRE

Wang, Kun; Peng, Xiaojue; Ji, Yanxiao; Yang, Pingfang; Zhu, Yingguo; Li, Shaoqing

2013-01-01

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 prot...

Study on thermal-hydraulic behavior in supersonic steam injector

International Nuclear Information System (INIS)

Abe, Yutaka; Fukuichi, Akira; Kawamoto, Yujiro; Iwaki, Chikako; Narabayashi, Tadashi; Mori, Michitsugu; Ohmori, Shuichi

2007-01-01

Supersonic steam injector is the one of the most possible devices aiming at simplifying system and improving the safety and the credibility for next-generation nuclear reactor systems. The supersonic steam injector has dual functions of a passive jet pump without rotating machine and a compact and high efficiency heat exchanger, because it is operated by the direct contact condensation between supersonic steam and subcooled water jet. It is necessary to clarify the flow behavior in the supersonic steam injector which is governed by the complicated turbulent flow with a great shear stress of supersonic steam. However, in previous study, there is little study about the turbulent heat transfer and flow behavior under such a great shear stress at the gas-liquid interface. In the present study, turbulent flow behavior including the effect of the interface between water jet and supersonic steam is developed based on the eddy viscosity model. Radial velocity distributions and the turbulent heat transfer are calculated with the model. The calculation results are compared with the experimental results done with the transparent steam injector. (author)

Production of a sterile species: Quantum kinetics

Science.gov (United States)

Boyanovsky, D.; Ho, C. M.

2007-10-01

Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is τdec=2/Γaa, but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: Γ1=Γaacos⁡2θm; Γ2=Γaasin⁡2θm where Γaa is the interaction rate of the active species in the absence of mixing and θm the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the “polarization vector” and show their equivalence to those obtained from the quantum master equation and effective action.

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.

Modelling studies of horizontal steam generator PGV-1000 with Cathare

Energy Technology Data Exchange (ETDEWEB)

Karppinen, I [VTT Energy, Espoo (Finland)

1996-12-31

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.

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

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

Thermo-hydraulic stability study of a steam generator

International Nuclear Information System (INIS)

Magni, M C; Marcel, C P; Delmastro, D F

2012-01-01

In this work a mathematical model developed to investigate the thermalhydraulic stability of a helically coiled steam generator is presented. Such a steam generator is prone to experiment density wave oscillations. The model is therefore used to analyze the stability of the CAREM-25 reactor steam generators. The model is linear, numerically non-diffusive and nodal. In addition, it is able to represent non-uniform heat transfer fluxes between the primary and secondary coolant circuits. By using this model the marginal stability condition is found by varying the inlet friction coefficient for different conditions. The results are then compared with those obtained with a different model for which a simple uniform heat flux profiled is assumed. It is found that with such simplification the density waves instability mechanism is overestimated in a wide range of operating powers. For very low powers, in the contrary, the so-called uniform model underestimates the stabilizing inlet friction and therefore it gives non-conservative results. With the use of the more realistic non-uniform power profile model, it was possible to determine that, for a CAREM-25 steam generator, the most stable conditions is found at 60MW when the reactor operates at nominal pressure. Moreover, it is found that at high power levels the stability performance is dominated by the two-phase friction component while at low power levels the friction component originated in the over heated steam region prevail (author)

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

Experimental investigations of heat exchange and hydrodynamics on models of a VG-400 steam generator tube bundle made up of small diameter helicoils

International Nuclear Information System (INIS)

Golovko, V.F; Ivaskov, N.A.; Obukhov, P.I.; Pospelov, V.N.; Sergeev, A.I.

1988-01-01

Features of HTGR steam generators having heat exchange surface made up of small diameter helicoils are discussed in the paper. A general approach to optimization of thermohydraulic characteristics BΓW-400 steam generator design backed by calculation and experiment are given. Main results of steam generator assembly's model aerodynamic test are presented. Data of thermohydraulic tests of a single tube model in a helium heated test rig are discussed. (author)

Study on sensory test of irradiated spices

International Nuclear Information System (INIS)

Chiba, Etsuko; Iizuka, Tomoko; Ichikawa, Mariko; Kobayashi, Yasuhiko; Ukai, Mitsuko; Kikuchi, Masahiro

2016-01-01

For the spices used in curry dishes and the spices used except for curry dishes, the effects of irradiation sterilization and conventional superheated-steam sterilization were compared with sensory test. As for spices, superheated-steam sterilization reduces aroma and changes color tone compared with irradiation sterilization. Even with cooked curry, radiologically sterilized products were stronger in 'flavor before sample tasting' or 'spicy taste during sample tasting' with statistically significant difference compared with superheated-steam sterilized products. As for the comparison with spices themselves, red pepper and white/black pepper tended to be stronger in taste and pungent taste than radiologically sterilized products. In addition, superheated-steam sterilized products of red hot pepper and turmeric were very different in color from untreated products, while radiologically sterilized products showed a little difference. When comparing color and flavor in a 2D map, it was found at a glance that the radiologically sterilized product was close to the untreated product. Thia map can easily convince the merit of irradiation sterilization, and it was found to be effective for promoting risk communication. In the case of white pepper, the radiologically sterilized product showed more strong pungent than the superheated-steam sterilized product with statistically significant difference. However, not only the strength difference but also qualitative difference was perceived in flavor. (A.O.)

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.

Steam reforming of different biomass tar model compounds over Ni/Al_2O_3 catalysts

International Nuclear Information System (INIS)

Artetxe, Maite; Alvarez, Jon; Nahil, Mohamad A.; Olazar, Martin; Williams, Paul T.

2017-01-01

Highlights: • Order of reactivity: anisole > furfural > indene > phenol > toluene > methyl naphthalene. • Higher coke deposition for oxygenates (1.5–2.8%) than for aromatics (0.5–0.8%). • Amorphous coke is deposited for oxygenates and filamentous carbon for aromatics. • Ni content of 20 wt.% shows the higher conversion (90%) and H_2 potential (63%). - Abstract: This work focuses on the removal of the tar derived from biomass gasification by catalytic steam reforming on Ni/Al_2O_3 catalysts. Different tar model compounds (phenol, toluene, methyl naphthalene, indene, anisole and furfural) were individually steam reformed (after dissolving each one in methanol), as well as a mixture of all of them, at 700 °C under a steam/carbon (S/C) ratio of 3 and 60 min on stream. The highest conversions and H_2 potential were attained for anisole and furfural, while methyl naphthalene presented the lowest reactivity. Nevertheless, the higher reactivity of oxygenates compared to aromatic hydrocarbons promoted carbon deposition on the catalyst (in the 1.5–2.8 wt.% range). When the concentration of methanol is decreased in the feedstock and that of toluene or anisole is increased, the selectivity to CO is favoured in the gaseous products, thus increasing coke deposition on the catalyst and decreasing catalyst activity for the steam reforming reaction. Moreover, an increase in Ni loading in the catalyst from 5 to 20% enhances carbon conversion and H_2 formation in the steam reforming of a mixture of all the model compounds studied, but these values decrease for a Ni content of 40%. Coke formation also increased by increasing Ni loading, attaining its maximum value for 40% Ni (6.5 wt.%).

Transient analysis of a U-tube natural circulation steam generator

Energy Technology Data Exchange (ETDEWEB)

Gaikwad, A J; Kumar, Rajesh; Bhadra, Anu; Chakraborty, G; Venkat Raj, V [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai (India)

1994-06-01

A computer code has been developed, for transient thermal-hydraulic analysis of proposed 500 MWe PHWR steam generator. The transient behaviour of a nuclear power plant is very much dependent on the steam generator performance, as it provides a thermal linkage between the primary and secondary systems. Study of dynamics of steam generator is essential for over all power plant dynamics as well as design of control systems for steam generator. A mathematical model has been developed for the simulation of thermal-hydraulic phenomena in a U tube natural circulation steam generator. Fluid model is based on one dimensional, nonlinear, single fluid conservation equations of mass, momentum, energy and equation of state. This model includes coupled two phase flow heat transfer and natural circulation. The model accounts for both compressibility and thermal expansion effects. The process simulation and results obtained for transients such as step change in load and total loss of feed water are presented. (author). 5 refs., 7 figs.

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.

Design of a partial inter-tube lancing system actuated by hydraulic power for type F model steam generator in nuclear power plant

International Nuclear Information System (INIS)

Kim, S. T.; Jeong, W. T.

2008-01-01

The sludge grown up in steam generators of nuclear power plants shortens the life-cycle of steam generators and reduces the output of power plants. So KHNP(Korea Hydro and Nuclear Power), the only nuclear power utility in Korea, removes it periodically using a steam generator lancing system during the outage of plants for an overhaul. KEPRI(Korea Electric Power Research Institute) has developed lancing systems with high pressured water nozzle for steam generators of nuclear power plants since 2001. In this paper, the design of a partial inter-tube lancing system for model F type steam generators will be described. The system is actuated without a DC motor inner steam generators because the motors in a steam generator make a trouble from high intensity of radioactivity as a break down

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)

PMK-2. Experimental study on steam generator behaviour

Energy Technology Data Exchange (ETDEWEB)

Ezsoel, G.; Szabados, L.; Trosztel, I. [KFKI Atomic Energy Research Inst., Budabest (Hungary)

1995-12-31

The PMK-2 is a full pressure scaled-down model of the Paks Nuclear Power Plant, with a 1:2070 scaling ratio for the volume and power. It has a steam generator model which is a vertical section of the horizontal steam generator. The model has hot and cold collectors similarly to the steam generators of the plant. The heat transfer tubes are horizontal tubes. There are 82 rows of tubes and the elevations, as well as the heat transfer surface distribution is the same as in the plant. The elevation of the feed water supply is similar to that of the plant. To study the temperature distribution in both the primary and the secondary side several thermocouples are built in, in addition to the overall instrumentation of the loop which has again a high number of measurement channels. Paper gives a description and results of SPE-4, with special respect to the steam generator behaviour in both steady state and transient conditions. Axial distribution of coolant and feedwater temperatures are given for the primary and the secondary side of hot and cold collectors and the temperature distribution in the centre of steam generator. (orig.).

PMK-2. Experimental study on steam generator behaviour

Energy Technology Data Exchange (ETDEWEB)

Ezsoel, G; Szabados, L; Trosztel, I [KFKI Atomic Energy Research Inst., Budabest (Hungary)

1996-12-31

The PMK-2 is a full pressure scaled-down model of the Paks Nuclear Power Plant, with a 1:2070 scaling ratio for the volume and power. It has a steam generator model which is a vertical section of the horizontal steam generator. The model has hot and cold collectors similarly to the steam generators of the plant. The heat transfer tubes are horizontal tubes. There are 82 rows of tubes and the elevations, as well as the heat transfer surface distribution is the same as in the plant. The elevation of the feed water supply is similar to that of the plant. To study the temperature distribution in both the primary and the secondary side several thermocouples are built in, in addition to the overall instrumentation of the loop which has again a high number of measurement channels. Paper gives a description and results of SPE-4, with special respect to the steam generator behaviour in both steady state and transient conditions. Axial distribution of coolant and feedwater temperatures are given for the primary and the secondary side of hot and cold collectors and the temperature distribution in the centre of steam generator. (orig.).

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

Observance of Sterilization Protocol Guideline Procedures of Critical Instruments for Preventing Iatrogenic Transmission of Creutzfeldt-Jakob Disease in Dental Practice in France, 2017

Directory of Open Access Journals (Sweden)

Denis Bourgeois

2018-04-01

Full Text Available Effective sterilization of reusable instruments contaminated by Creutzfeldt–Jakob disease in dental care is a crucial issue for public health. The present cross-sectional study investigated how the recommended procedures for sterilization were implemented by French dental practices in real-world settings. A sample of dental practices was selected in the French Rhône-Alpes region. Data were collected by a self-questionnaire in 2016. Sterilization procedures (n = 33 were classified into 4 groups: (1 Pre-sterilization cleaning of reusable instruments; (2 Biological verification of sterilization cycles—Monitoring steam sterilization procedures; (3 Autoclave performance and practitioner knowledge of autoclave use; (4 Monitoring and documentation of sterilization procedures—Tracking and tracing the instrumentation. Answers were provided per procedure, along with the global implementation of procedures within a group (over 80% correctly performed. Then it was verified how adherence to procedure groups varied with the size of the dental practice and the proportion of dental assistants within the team. Among the 179 questionnaires available for the analyses, adherence to the recommended procedures of sterilization noticeably varied between practices, from 20.7% to 82.6%. The median percentages of procedures correctly implemented per practice were 58.1%, 50.9%, 69.2% and 58.2%, in Groups 1, 2, 3 and 4, respectively (corresponding percentages for performing over 80% of the procedures in the group: 23.4%, 6.6%, 46.6% and 38.6%. Dental practices ≥ 3 dental units performed significantly better (>80% procedures of Groups 2 and 4 (p = 0.01 and p = 0.002, respectively, while no other significant associations emerged. As a rule, practices complied poorly with the recommended procedures, despite partially improved results in bigger practices. Specific training regarding sterilization procedures and a better understanding of the reasons leading to their

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.)

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.

Mathematical modelling of a steam boiler room to research thermal efficiency

International Nuclear Information System (INIS)

Bujak, J.

2008-01-01

This paper introduces a mathematical model of a boiler room to research its thermal efficiency. The model is regarded as an open thermodynamic system exchanging mass, energy, and heat with the atmosphere. On those grounds, the energy and energy balance were calculated. Here I show several possibilities concerning how this model may be applied. Test results of the coefficient of thermal efficiency were compared to a real object, i.e. a steam boiler room of the Provincial Hospital in Wloclawek (Poland). The tests were carried out for 18 months. The results obtained in the boiler room were used for verification of the mathematical model

Dimensional analysis of small-scale steam explosion experiments

International Nuclear Information System (INIS)

Huh, K.; Corradini, M.L.

1986-01-01

Dimensional analysis applied to Nelson's small-scale steam explosion experiments to determine the qualitative effect of each relevant parameter for triggering a steam explosion. According to experimental results, the liquid entrapment model seems to be a consistent explanation for the steam explosion triggering mechanism. The three-dimensional oscillatory wave motion of the vapor/liquid interface is analyzed to determine the necessary conditions for local condensation and production of a coolant microjet to be entrapped in fuel. It is proposed that different contact modes between fuel and coolant may involve different initiation mechanisms of steam explosions

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.

Prospects of radiation sterilization of medical devices

International Nuclear Information System (INIS)

Hosobuchi, Kazunari

1992-01-01

Since radiation sterilization was first introduced in the United States in 1956 in the field of disposable medical devices, it has become an indispensable technique for sterilization because of the following reasons: (1) introduction into dialyzers, (2) introduction in medical device makers, (3) development of disposable medical devices associated with developing both high molecular chemistry and cool sterilization, (4) rationality of sterilization process, and (5) problems of sterilization with ethylene oxide gas. To promote the further development of radiation sterilization, the following items are considered necessary: (1) an increase in the number of facilities for radiation sterilization, (2) recommendation of the international standardization of sterilization method, (3) decrease in radiation doses associated with sterilization, (4) development of electron accelerators and bremsstrahlung equipments for radiation sources, and (5) simplification of sterilization process management. Factors precluding the development of radiation sterilization are: (1) development of other methods than radiation sterilization, (2) development of technique for sterile products, (3) high facility cost, (4) high irradiation cost, (5) benefits and limits of sterilization markets, and (6) influences of materials. (N.K.)

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)

Droplet rotation model apply in steam uniform flow and gravitational field

International Nuclear Information System (INIS)

Zhang Jinyi; Bo Hanliang; Sun Yuliang; Wang Dazhong

2012-01-01

The mechanism droplet movement behavior and the qualitative description of droplet trajectory in the steam uniform flow field in the gravitational field were researched with droplet rotation model. According to the mechanism of gravitational field and uniform flow fields, the effects on droplets movement were analyzed and the importance of lift forces was also discussed. Finally, a general trajectory and mechanism of the droplets movement was derived which lays the groundwork for the qualitative analysis of the single-drop model and could be general enough to be used in many applications. (authors)

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

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).

An expert system for steam generator maintenance

International Nuclear Information System (INIS)

Remond, A.

1988-01-01

The tube bundles in PWR steam generators are, by far, the major source of problems whether they are due to primary and secondary side corrosion mechanisms or to tube vibration-induced wear at tube support locations. Because of differences in SG operating, materials, and fabrication processes, the damage may differ from steam generator to steam generator. MPGV, an expert system for steam generator maintenance uses all steam generator data containing data on materials, fabrication processes, inservice inspection, and water chemistry. It has access to operational data for individual steam generators and contains models of possible degradation mechanisms. The objectives of the system are: · Diagnosing the most probable degradation mechanism or mechanisms by reviewing the entire steam generator history. · Identifying the tubes most exposed to future damage and evaluating the urgency of repair by simulating the probable development of the problem in time. · Establishing the appropriate preventive actions such as repair, inspection or other measures and establishing an action schedule. The system is intended for utilities either for individual plants before each inspection outage or any time an incident occurs or for a set of plants through a central MPGV center. (author)

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.

Impact of sterile neutrinos on nuclear-assisted cLFV processes

Energy Technology Data Exchange (ETDEWEB)

Abada, A. [Laboratoire de Physique Théorique, CNRS,University Paris-Sud, Université Paris-Saclay, 91405 Orsay (France); Romeri, V. De; Teixeira, A.M. [Laboratoire de Physique Corpusculaire, CNRS/IN2P3 - UMR 6533,Campus des Cézeaux, 24 Av. des Landais, F-63177 Aubière Cedex (France)

2016-02-12

We discuss charged lepton flavour violating processes occurring in the presence of muonic atoms, such as muon-electron conversion in nuclei CR(μ−e, N), the (Coulomb enhanced) decay of muonic atoms into a pair of electrons BR(μ{sup −}e{sup −}→e{sup −}e{sup −}, N), as well as Muonium conversion and decay, Mu− (Mu)-bar and Mu→e{sup +}e{sup −}. Any experimental signal of these observables calls for scenarios of physics beyond the Standard Model. In this work, we consider minimal extensions of the Standard Model via the addition of sterile fermions, providing the corresponding complete analytical expressions for all the considered observables. We first consider an “ad hoc” extension with a single sterile fermion state, and investigate its impact on the above observables. Two well motivated mechanisms of neutrino mass generation are then considered: the Inverse Seesaw embedded into the Standard Model, and the νMSM. Our study reveals that, depending on their mass range and on the active-sterile mixing angles, sterile neutrinos can give significant contributions to the above mentioned observables, some of them even lying within present and future sensitivity of dedicated cLFV experiments. We complete the analysis by confronting our results to other (direct and indirect) searches for sterile fermions.

Research on simulation of supercritical steam turbine system in large thermal power station

Science.gov (United States)

Zhou, Qiongyang

2018-04-01

In order to improve the stability and safety of supercritical steam turbine system operation in large thermal power station, the body of the steam turbine is modeled in this paper. And in accordance with the hierarchical modeling idea, the steam turbine body model, condensing system model, deaeration system model and regenerative system model are combined to build a simulation model of steam turbine system according to the connection relationship of each subsystem of steam turbine. Finally, the correctness of the model is verified by design and operation data of the 600MW supercritical unit. The results show that the maximum simulation error of the model is 2.15%, which meets the requirements of the engineering. This research provides a platform for the research on the variable operating conditions of the turbine system, and lays a foundation for the construction of the whole plant model of the thermal power plant.

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.

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.

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)

Application of Integrated Neural Network Method to Fault Diagnosis of Nuclear Steam Generator

International Nuclear Information System (INIS)

Zhou Gang; Yang Li

2009-01-01

A new fault diagnosis method based on integrated neural networks for nuclear steam generator (SG) was proposed in view of the shortcoming of the conventional fault monitoring and diagnosis method. In the method, two neural networks (ANNs) were employed for the fault diagnosis of steam generator. A neural network, which was used for predicting the values of steam generator operation parameters, was taken as the dynamics model of steam generator. The principle of fault monitoring method using the neural network model is to detect the deviations between process signals measured from an operating steam generator and corresponding output signals from the neural network model of steam generator. When the deviation exceeds the limit set in advance, the abnormal event is thought to occur. The other neural network as a fault classifier conducts the fault classification of steam generator. So, the fault types of steam generator are given by the fault classifier. The clear information on steam generator faults was obtained by fusing the monitoring and diagnosis results of two neural networks. The simulation results indicate that employing integrated neural networks can improve the capacity of fault monitoring and diagnosis for the steam generator. (authors)

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)

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...

Passive system with steam-water injector for emergency supply of NPP steam generators

International Nuclear Information System (INIS)

Il'chenko, A.G.; Strakhov, A.N.; Magnitskij, D.N.

2009-01-01

The calculation results of reliability indicators of emergency power supply system and emergency feed-water supply system of serial WWER-1000 unit are presented. To ensure safe water supply to steam generators during station blackout it was suggested using additional passive emergency feed-water system with a steam-water injector working on steam generators dump steam. Calculated analysis of steam-water injector operating capacity was conducted at variable parameters of steam at the entrance to injector, corresponding to various moments of time from the beginning of steam-and-water damping [ru

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)

Cost-effectiveness analysis comparing the essure tubal sterilization procedure and laparoscopic tubal sterilization.

Science.gov (United States)

Thiel, John A; Carson, George D

2008-07-01

To analyze the financial implications of establishing a hysteroscopic sterilization program using the Essure micro-insert tubal sterilization system in an ambulatory clinic. A retrospective cohort study (Canadian Task Force classification Type II-2), in an ambulatory women's health clinic in a tertiary hospital, of 108 women undergoing Essure coil insertion between 2005 and 2006, and 104 women undergoing laparoscopic tubal sterilization for permanent sterilization between 2001 and 2004. The Essure procedures used a 4 mm single channel operative hysteroscope and conscious sedation (fentanyl and midazolam); the laparoscopic tubal sterilizations were completed under general anaesthesia with a 7 mm laparoscope and either bipolar cautery or Filshie clips. Costs associated with the procedure, follow-up, and management of any complications (including nursing, hospital charges, equipment, and disposables) were tabulated. The Essure coils were successfully placed on the first attempt in 103 of 108 women (95%). Three patients required a second attempt to complete placement and two patients required laparoscopic tubal sterilization after an unsuccessful Essure. All 104 laparoscopic tubals were completed on the first attempt with no complications reported. The total cost for the 108 Essure procedures, including follow-up evaluation, was $138,996 or $1287 per case. The total cost associated with the 104 laparoscopic tubal sterilization procedures was $148,227 or $1398 per case. The incremental cost-effectiveness ratio was $111. The Essure procedure in an ambulatory setting resulted in a statistically significant cost saving of $111 per sterilization procedure. Carrying out the Essure procedure in an ambulatory setting frees space in the operating room for other types of cases, improving access to care for more patients.

Thermal hydraulic studies in steam generator test facility

International Nuclear Information System (INIS)

Vinod, V.; Suresh Kumar, V.A.; Noushad, I.B.; Ellappan, T.R.; Rajan, K.K.; Rajan, M.; Vaidyanathan, G.

2005-01-01

Full text of publication follows: A 500 MWe fast breeder reactor is being constructed at Kalpakkam, India. This is a sodium cooled reactor with two primary and two secondary sodium loops with total 8 steam generators. The typical advantage of fast breeder plants is the high operating temperature of steam cycles and the high plant efficiency. To produce this high pressure and high temperature steam, once through straight tube vertical sodium heated steam generators are used. The steam is generated from the heat produced in the reactor core and being transported through primary and secondary sodium circuits. The steam generator is a 25 m high middle supported steam generator with expansion bend and 23 m heat transfer length. Steam Generator Test Facility (SGTF) constructed at Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam aims at performing various tests on a 5.5 MWt steam generator. This vertically simulated test article is similar in all respects to the proposed 157 MWt steam generator module for the Prototype Fast Breeder Reactor (PFBR), with reduced number of tubes. Heat transfer performance tests are done with this 19 tube steam generator at various load conditions. Sodium circuit for the SGTF is equipped with oil fired heater as heat source and centrifugal sodium pump, to pump sodium at 105 m 3 /hr flow rate. Other typical components like sodium to air heat exchanger, sodium purification system and hydrogen leak detection system is also present in the sodium circuit. High pressure steam produced in the steam generator is dumped in a condenser and recycled. Important tests planned in SGTF are the heat transfer performance test, stability test, endurance test and performance test of steam generator under various transients. The controlled operation of steam generator will be studied with possible control schemes. A steady state simulation of the steam generator is done with a mathematical model. This paper gives the details of heat transfer

Sterile Neutrinos in Cold Climates

International Nuclear Information System (INIS)

Jones, Benjamin J.P.

2015-01-01

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 sin 2 2θ 24 ≤ 0.02 at m 2 ~ 0.3 eV 2 , and the LSND and MiniBooNE allowed regions are excluded at

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.)

Genome-wide dissection of hybrid sterility in Drosophila confirms a polygenic threshold architecture.

Science.gov (United States)

Morán, Tomás; Fontdevila, Antonio

2014-01-01

To date, different studies about the genetic basis of hybrid male sterility (HMS), a postzygotic reproductive barrier thoroughly investigated using Drosophila species, have demonstrated that no single major gene can produce hybrid sterility without the cooperation of several genetic factors. Early work using hybrids between Drosophila koepferae (Dk) and Drosophila buzzatii (Db) was consistent with the idea that HMS requires the cooperation of several genetic factors, supporting a polygenic threshold (PT) model. Here we present a genome-wide mapping strategy to test the PT model, analyzing serially backcrossed fertile and sterile males in which the Dk genome was introgressed into the Db background. We identified 32 Dk-specific markers significantly associated with hybrid sterility. Our results demonstrate 1) a strong correlation between the number of segregated sterility markers and males' degree of sterility, 2) the exchangeability among markers, 3) their tendency to cluster into low-recombining chromosomal regions, and 4) the requirement for a minimum number (threshold) of markers to elicit sterility. Although our findings do not contradict a role for occasional major hybrid-sterility genes, they conform more to the view that HMS primarily evolves by the cumulative action of many interacting genes of minor effect in a complex PT architecture.

Materials choices for the advanced LWR steam generators

International Nuclear Information System (INIS)

Paine, J.P.N.; Shoemaker, C.E.; McIlree, A.R.

1987-01-01

Current light water reactor (LWR) steam generators have been affected by a variety of corrosion and mechanical damage degradation mechanisms. Included are wear caused by tube vibration, intergranular corrosion, pitting, and thinning or wastage of the steam generator tubing and accelerated corrosion of carbon steel supports (denting). The Electric Power Research Institute (EPRI) and the Steam Generator Owners Groups (I, II) have sponsored laboratory and field studies to provide ameliorative actions for the majority of the damage forms experienced to date. Some of the current corrosion mechanisms are aggravated or caused by unique materials choices or materials interactions. New materials have been proposed and at least partially qualified for use in replacement model steam generators, including an advanced LWR design. In so far as possible, the materials choices for the advanced LWR steam generator avoid the corrosion pitfalls seemingly inherent in the current designs. The EPRI Steam Generator Project staff has recommended materials and design choices for a new steam generator. Based on these recommendations we believe that the advanced LWR steam generators will be much less affected by corrosion and mechanical damage mechanisms than are now experienced

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

Effect of heat transfer tube leak on dynamic characteristic of steam generator

International Nuclear Information System (INIS)

Sun Baozhi; Shi Jianxin; Li Na; Zheng Lusong; Liu Shanghua; Lei Yu

2015-01-01

Taking the steam generator of Daya Bay Nuclear Power Station as the research object, one-dimensional dynamic model of the steam generator based on drift flux theory and leak model of heat transfer tube were established. Steady simulation of steam generator under different conditions was carried out. Based on verifying the drift flux model and leak model of heat transfer tube, the effect of leak location and flow rate under different conditions on steam generator's key parameters was studied. The results show that the drift flux model and leak model can reflect the law of key parameter change accurately such as vapor mass fraction and steam pressure under different leak cases. The variation of the parameters is most apparent when the leak is at the entrance of boiling section and vapor mass fraction varies from 0.261 to 0.163 when leakage accounts for 5% of coolant flow rate. The successful prediction of the effect of heat transfer tube leak on dynamic characteristics of the steam generator based on drift flux theory supplies some references for monitoring and taking precautionary measures to prevent heat transfer tube leak accident. (authors)

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)

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.

Searching for sterile neutrinos in dynamical dark energy cosmologies

Science.gov (United States)

Feng, Lu; Zhang, Jing-Fei; Zhang, Xin

2018-05-01

We investigate how the dark energy properties change the cosmological limits on sterile neutrino parameters by using recent cosmological observations. We consider the simplest dynamical dark energy models, the wCDM model and the holographic dark energy (HDE) model, to make an analysis. The cosmological observations used in this work include the Planck 2015 CMB temperature and polarization data, the baryon acoustic oscillation data, the type Ia supernova data, the Hubble constant direct measurement data, and the Planck CMB lensing data. We find that, m v,terile ff energy properties could significantly influence the constraint limits of sterile neutrino parameters.

Axion-assisted production of sterile neutrino dark matter

Energy Technology Data Exchange (ETDEWEB)

Berlin, Asher; Hooper, Dan

2017-04-12

Sterile neutrinos can be generated in the early universe through oscillations with active neutrinos and represent a popular and well-studied candidate for our universe's dark matter. Stringent constraints from X-ray and gamma-ray line searches, however, have excluded the simplest of such models. In this letter, we propose a novel alternative to the standard scenario in which the mixing angle between the sterile and active neutrinos is a dynamical quantity, induced through interactions with a light axion-like field. As the energy density of the axion-like particles is diluted by Hubble expansion, the degree of mixing is reduced at late times, suppressing the decay rate and easily alleviating any tension with X-ray or gamma-ray constraints. We present a simple model which illustrates the phenomenology of this scenario, and also describe a framework in which the QCD axion is responsible for the production of sterile neutrinos in the early universe.

Remodeling of ACL Allografts is Inhibited by Peracetic Acid Sterilization

Science.gov (United States)

Gonnermann, Johannes; Kamp, Julia; Przybilla, Dorothea; Pruss, Axel

2008-01-01

Sterilization of allografts for anterior cruciate ligament (ACL) reconstruction has become an important prerequisite to prevent disease transmission. However, current sterilization techniques impair the biological or mechanical properties of such treated grafts. Peracetic acid (PAA) has been successfully used to sterilize bone allografts without these disadvantages and does not impair the mechanical properties of soft tissue grafts in vitro. We asked whether PAA sterilization would influence recellularization, restoration of crimp length and pattern, and revascularization of ACL grafts during early healing. We used an in vivo sheep model for open ACL reconstruction. We also correlated the histologic findings with the restoration of anteroposterior stability and structural properties during load-to-failure testing. PAA slowed remodeling activity at 6 and 12 weeks compared to nonsterilized allografts and autografts. The mechanical properties of PAA grafts were also reduced compared to these control groups at both time points. We conclude PAA sterilization currently should not be used to sterilize soft tissue grafts typically used in ACL reconstruction. PMID:18491201

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)

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)

Three-Dimensional Modeling of a Steam-Line Break in a Boiling Water Reactor

International Nuclear Information System (INIS)

Tinoco, Hernan

2002-01-01

Because of weld problems, the core grids of Units 1 and 2 at the Forsmark nuclear power plant have been replaced by grids of a new design, consisting of a single machined piece without welds. The qualifying structural analysis has been carried out considering dynamic loads, which implies that even loss-of-coolant accidents have to be included. Therefore, a detailed time description of the loads acting on the different internal parts of the reactor is needed. To achieve sufficient space and time resolution, a computational fluid dynamics (CFD) analysis was considered to be a viable alternative.A CFD analysis of a steam-line break in the boiling water reactor of Unit 2 is the subject of this work. The study is based on the assumption that the timescale of the transient analysis is smaller than the relaxation time of the water-steam system. Therefore, a simulation of only the upper, steam part of the reactor with no two-phase effects (flashing) is feasible.The results obtained display a rather complex behavior of the decompression process, forcing the analysis of the pressure field to be accomplished through animation. In contrast, the computed instantaneous forces over different internal parts oscillate regularly and are approximately twice the forces estimated in the past by simpler methods, with frequencies of 30 to 40 Hz; top amplitudes of ∼1.64 MN; and relatively low damping, ∼25% after 0.5 s.According to the present results, this type of modeling is physically meaningful for simulation timescales smaller than the water-steam relaxation time, i.e., ∼0.5 s at reactor conditions. At larger times, a two-phase model is necessary to describe the decompression process since two-phase effects are dominant. The results have not yet been validated with experiments, but validation computations will be run in the future for comparison with results of the Marviken tests

Eugenics and Involuntary Sterilization: 1907-2015.

Science.gov (United States)

Reilly, Philip R

2015-01-01

In England during the late nineteenth century, intellectuals, especially Francis Galton, called for a variety of eugenic policies aimed at ensuring the health of the human species. In the United States, members of the Progressive movement embraced eugenic ideas, especially immigration restriction and sterilization. Indiana enacted the first eugenic sterilization law in 1907, and the US Supreme Court upheld such laws in 1927. State programs targeted institutionalized, mentally disabled women. Beginning in the late 1930s, proponents rationalized involuntary sterilization as protecting vulnerable women from unwanted pregnancy. By World War II, programs in the United States had sterilized approximately 60,000 persons. After the horrific revelations concerning Nazi eugenics (German Hereditary Health Courts approved at least 400,000 sterilization operations in less than a decade), eugenic sterilization programs in the United States declined rapidly. Simplistic eugenic thinking has faded, but coerced sterilization remains widespread, especially in China and India. In many parts of the world, involuntary sterilization is still intermittently used against minority groups.

Analytical model of impurity concentration during steam generation in permeable porous structures

International Nuclear Information System (INIS)

Polonskii, V.S.; Orlov, A.V.

1993-01-01

A model is proposed to describe the mass transfer of impurities during steam generation on a surface covered by porous deposits of corrosion products. The model is based on replacement of the actual structure of the deposits by a system of cylindrical fluid and vapor channels in which the flow of vapor and a liquid film is described by the Navier-Stokes equations. The driving force in the process is assumed to be the difference in the Laplacian pressures due to surface tension on the front and back sides of elongated vapor bubbles. Calculations performed for the operating conditions of the drums of the steam generators of nuclear power plants with water-moderated water-cooled reactors show that the mass transfer rate is extremely low in the gaps in cold drums and that the concentration of aggressive impurities deep within these channels may reach two or more orders of magnitude-thus leading to rapid corrosion. Almost complete vaporization occurs in the capillary channels of hot drums with deposits, which probably precludes corrosion in the channel depths. However, corrosion damage remains a possibility at the entrance to the channels (on the side of the second loop)

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

HTGR steam generator development

International Nuclear Information System (INIS)

Schuetzenduebel, W.G.; Hunt, P.S.; Weber, M.

1976-01-01

More than 40 gas-cooled reactor plants have produced in excess of 400 reactor years of operating experience which have proved a reasonably high rate of gas-cooled reactor steam generator availability. The steam generators used in these reactors include single U-tube and straight-tube steam generators as well as meander type and helically wound or involute tube steam generators. It appears that modern reactors are being equipped with helically wound steam generators of the once-through type as the end product of steam generator evolution in gas-cooled reactor plants. This paper provides a general overview of gas-cooled reactor steam generator evolution and operating experience and shows how design criteria and constraints, research and development, and experience data are factored into the design/development of modern helically wound tube steam generators for the present generation of gas-cooled reactors

Effects of steam autoclave treatment on Geobacillus stearothermophilus spores.

Science.gov (United States)

Huesca-Espitia, L C; Suvira, M; Rosenbeck, K; Korza, G; Setlow, B; Li, W; Wang, S; Li, Y-Q; Setlow, P

2016-11-01

To determine the mechanism of autoclave killing of Geobacillus stearothermophilus spores used in biological indicators (BIs) for steam autoclave sterilization, and rates of loss of spore viability and a spore enzyme used in BIs. Spore viability, dipicolinic acid (DPA) release, nucleic acid staining, α-glucosidase activity, protein structure and mutagenesis were measured during autoclaving of G. stearothermophilus spores. Loss of DPA and increases in spore core nucleic acid staining were slower than loss of spore viability. Spore core α-glucosidase was also lost more slowly than spore viability, although soluble α-glucosidase in spore preparations was lost more rapidly. However, spores exposed to an effective autoclave sterilization lost all viability and α-glucosidase activity. Apparently killed autoclaved spores were not recovered by artificial germination in supportive media, much spore protein was denatured during autoclaving, and partially killed autoclave-treated spore preparations did not acquire mutations. These results indicate that autoclave-killed spores cannot be revived, spore killing by autoclaving is likely by protein damage, and spore core α-glucosidase activity is lost more slowly than spore viability. This work provides insight into the mechanism of autoclave killing of spores of an organism used in BIs, and that a spore enzyme in a BI is more stable to autoclaving than spore viability. © 2016 The Society for Applied Microbiology.

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)

Analysis of the Instability Phenomena Caused by Steam in High-Pressure Turbines

Directory of Open Access Journals (Sweden)

Paolo Pennacchi

2011-01-01

Full Text Available Instability phenomena in steam turbines may happen as a consequence of certain characteristics of the steam flow as well as of the mechanical and geometrical properties of the seals. This phenomenon can be modeled and the raise of the steam flow and pressure causes the increase of the cross coupled coefficients used to model the seal stiffness. As a consequence, the eigenvalues and eigenmodes of the mathematical model of the machine change. The real part of the eigenvalue associated with the first flexural normal mode of the turbine shaft may become positive causing the conditions for unstable vibrations. The original contribution of the paper is the application of a model-based analysis of the dynamic behavior of a large power unit, affected by steam-whirl instability phenomena. The model proposed by the authors allows studying successfully the experimental case. The threshold level of the steam flow that causes instability conditions is analyzed and used to define the stability margin of the power unit.

The chemical kinetics of the reactions of lithium with steam-air mixtures

International Nuclear Information System (INIS)

Barnett, D.S.; Kazimi, M.S.

1989-04-01

This work involved the experimental and analytical determination of the consequences of lithium fires in the presence of steam. Experiments were performed to characterize the chemical reactions of lithium with steam-nitrogen and steam-air mixtures. Models were introduced in the LITFIRE code to describe lithium fires in the presence of steam inside the containment building and plasma chamber of a hypothetical fusion reactor. The code was also equipped with the capability to determine the effects of decay heat and lithium fire on the temperature response of the reactor first wall in the event of a coolant disturbance. Forty-two kinetics experiments were performed in which a stream of steam-nitrogen or steam-air was passed over and reacted with approximately three grams of lithium heated to a predetermined temperature. The lithium reaction rates with the constituent gases were measured and characterized for a wide range of lithium temperatures and gas compositions. Experiments were performed with steam molar concentrations of 5, 15 and 30% and lithium temperatures ranging from 400 to 1100 degree C, inclusive. The LITFIRE code was modified to enable it to model the interactions of lithium with steam-air atmospheres. Results of the reaction kinetics experiments were used in the reaction model, and the heat transfer model was expanded to allow it to handle condensible atmospheres. Three groups of accidents were investigated: a spill on the containment building floor, a spill inside the reactor plasma chamber, and a spill inside the plasma chamber with steam injection to the containment building simulating a steam line break. The results were compared to dry air cases under the same conditions. 23 refs., 66 figs., 18 tabs

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...

Procedure for generating steam and steam generator for operating said procedure

International Nuclear Information System (INIS)

Chlique, Bernard.

1975-01-01

This invention concerns the generation of steam by bringing the water to be vaporised into indirect thermal exchange relation with the heating steam which condenses when passing in series, along alternate routes, through bundles of tubes immersed in a vaporising chamber. A number of steam generators working on this principle already exist. The purpose of the invention is to modify the operating method of these steam generators by means of a special disposition making it possible to build a compact unit including an additional bundle of tubes heated by the condensates collected at the outlet of each bundle through which the heating steam passes [fr

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

Development of a steam generator lancing system

International Nuclear Information System (INIS)

Jeong, Woo-Tae; Kim, Seok-Tae; Hong, Sung-Yull

2006-01-01

It is recommended to clean steam generators of nuclear power plants during plant outages. Under normal operations, sludge is created and constantly accumulates in the steam generators. The constituents of this sludge are different depending on each power plant characteristics. The sludge of the Kori Unit 1 steam generator, for example, was found to be composed of 93% ferrous oxide, 3% carbon and 1% of silica oxide and nickel oxide each. The research to develop a lancing system that would remove sludge deposits from the tubesheet of a steam generator was started in 1998 by the Korea Electric Power Research Institute (KEPRI) of the Korea Electric Power Corporation (KEPCO). The first commercial domestic lancing system in Korea, and KALANS-I Lancing System, was completed in 2000 for Kori Unit 1 for cleaning the tubesheet of its Westinghouse Delta-60 steam generator. Thereafter, the success of the development and site implementation of the KALANS-I lancing system for YGN Units 1 and 2 and Ulchin Units 3 and 4 was also realized in 2004 for sludge removal at those sites. The upper bundle cleaning system for Westinghouse model F steam generators is now under development

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)

Pain Associated With Hysteroscopic Sterilization

Science.gov (United States)

Levy, Jenna; Childers, Meredith E.

2007-01-01

Background and Objectives: The safety and efficacy of female hysteroscopic sterilization using the Essure system has been well documented. Given the marked differences in the execution of hysteroscopic and laparoscopic sterilization, the objective of this study was to assess the experience of pain postprocedure between the 2. Secondary end-points included postoperative pain medication, time to return to normal activities, postprocedure bleeding, and patient satisfaction. Methods: Twenty cases each of laparoscopic sterilization (LS) and hysteroscopic sterilization (HS) were performed. Patients were surveyed regarding their experience of pain immediately postoperatively, 1 week, and 4 weeks post-procedure. Results: The average pain score immediately postprocedure was significantly lower among HS patients than among LS patients (t=−8.17, P<.0001). One-week post-procedure, none of the patients in the HS group reported any pain, while the average pain score among the LS patients was 2.65 (t =−9.67, P<.0001). Four weeks post-procedure, women in the HS group continued to report no pain, 35% of the LS group continued to report some pain (t=−3.04, P=.004). Conclusions: Hysteroscopic sterilization offers a minimally invasive, less painful, equally efficacious modality for sterilization than laparoscopic sterilization and should be available to all women seeking permanent birth control. PMID:17651558

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.

Steam generator tube rupture simulation using extended finite element method

Energy Technology Data Exchange (ETDEWEB)

Mohanty, Subhasish, E-mail: smohanty@anl.gov; Majumdar, Saurin; Natesan, Ken

2016-08-15

Highlights: • Extended finite element method used for modeling the steam generator tube rupture. • Crack propagation is modeled in an arbitrary solution dependent path. • The FE model is used for estimating the rupture pressure of steam generator tubes. • Crack coalescence modeling is also demonstrated. • The method can be used for crack modeling of tubes under severe accident condition. - Abstract: A steam generator (SG) is an important component of any pressurized water reactor. Steam generator tubes represent a primary pressure boundary whose integrity is vital to the safe operation of the reactor. SG tubes may rupture due to propagation of a crack created by mechanisms such as stress corrosion cracking, fatigue, etc. It is thus important to estimate the rupture pressures of cracked tubes for structural integrity evaluation of SGs. The objective of the present paper is to demonstrate the use of extended finite element method capability of commercially available ABAQUS software, to model SG tubes with preexisting flaws and to estimate their rupture pressures. For the purpose, elastic–plastic finite element models were developed for different SG tubes made from Alloy 600 material. The simulation results were compared with experimental results available from the steam generator tube integrity program (SGTIP) sponsored by the United States Nuclear Regulatory Commission (NRC) and conducted at Argonne National Laboratory (ANL). A reasonable correlation was found between extended finite element model results and experimental results.

Steam generator tube rupture simulation using extended finite element method

International Nuclear Information System (INIS)

Mohanty, Subhasish; Majumdar, Saurin; Natesan, Ken

2016-01-01

Highlights: • Extended finite element method used for modeling the steam generator tube rupture. • Crack propagation is modeled in an arbitrary solution dependent path. • The FE model is used for estimating the rupture pressure of steam generator tubes. • Crack coalescence modeling is also demonstrated. • The method can be used for crack modeling of tubes under severe accident condition. - Abstract: A steam generator (SG) is an important component of any pressurized water reactor. Steam generator tubes represent a primary pressure boundary whose integrity is vital to the safe operation of the reactor. SG tubes may rupture due to propagation of a crack created by mechanisms such as stress corrosion cracking, fatigue, etc. It is thus important to estimate the rupture pressures of cracked tubes for structural integrity evaluation of SGs. The objective of the present paper is to demonstrate the use of extended finite element method capability of commercially available ABAQUS software, to model SG tubes with preexisting flaws and to estimate their rupture pressures. For the purpose, elastic–plastic finite element models were developed for different SG tubes made from Alloy 600 material. The simulation results were compared with experimental results available from the steam generator tube integrity program (SGTIP) sponsored by the United States Nuclear Regulatory Commission (NRC) and conducted at Argonne National Laboratory (ANL). A reasonable correlation was found between extended finite element model results and experimental results.

Multifactorial modelling of high-temperature treatment of timber in the saturated water steam medium

Science.gov (United States)

Prosvirnikov, D. B.; Safin, R. G.; Ziatdinova, D. F.; Timerbaev, N. F.; Lashkov, V. A.

2016-04-01

The paper analyses experimental data obtained in studies of high-temperature treatment of softwood and hardwood in an environment of saturated water steam. Data were processed in the Curve Expert software for the purpose of statistical modelling of processes and phenomena occurring during this process. The multifactorial modelling resulted in the empirical dependences, allowing determining the main parameters of this type of hydrothermal treatment with high accuracy.

Two different modelling methods of the saturated steam turbine load rejection

International Nuclear Information System (INIS)

Negreanu, Gabriel-Paul; Oprea, Ion

1999-01-01

One of the most difficult operation regimes of a steam turbine is the load rejection. It happens usually when the main switchgear of the unit closes unexpectedly due to some external or internal causes. In this moment, the rotor balance collapses: the motor momentum is positive, the resistant momentum is zero and the rotation velocity increases rapidly. When this process occurs, the over-speed protection should activate the emergency stop valves and the control and intercept valves in order to stop the steam admission into the turbine. The paper presents two differential approaches of the fluid dynamic processes from the flow sections of the saturated steam turbine of the NPP, where the laws of mass and energy conservation are applied. In this manner, the 'power and speed versus time' diagrams can be drawn. The main parameters of such technical problem are the closure low of the valves, the large volume of internal cavities, the huge inertial momentum of the rotor and especially the moisture of the steam that evaporates when the pressure decreases and generates an extra power in the turbine. (authors)

Searches for light sterile neutrinos with multitrack displaced vertices

Science.gov (United States)

Cottin, Giovanna; Helo, Juan Carlos; Hirsch, Martin

2018-03-01

We study discovery prospects for long-lived sterile neutrinos at the LHC with multitrack displaced vertices, with masses below the electroweak scale. We reinterpret current displaced vertex searches making use of publicly available, parametrized selection efficiencies for modeling the detector response to displaced vertices. We focus on the production of right-handed WR bosons and neutrinos N in a left-right symmetric model, and find poor sensitivity. After proposing a different trigger strategy (considering the prompt lepton accompanying the neutrino displaced vertex) and optimized cuts in the invariant mass and track multiplicity of the vertex, we find that the LHC with √{s }=13 TeV and 300 fb-1 is able to probe sterile neutrino masses between 10 GeV right-handed gauge boson mass of 2 TeV work joins other efforts in motivating dedicated experimental searches to target this low sterile neutrino mass region.

Thermo hydrodynamical analyses of steam generator of nuclear power plant

International Nuclear Information System (INIS)

Petelin, S.; Gregoric, M.

1984-01-01

SMUP computer code for stationary model of a U-tube steam generator of a PWR nuclear power plant was developed. feed water flow can enter through main and auxiliary path. The computer code is based on the one dimensional mathematical model. Among the results that give an insight into physical processes along the tubes of steam generator are distribution of temperatures, water qualities, heat transfer rates. Parametric analysis permits conclusion on advantage of each design solution regarding heat transfer effects and safety of steam generator. (author)

The not-so-sterile 4th neutrino: constraints on new gauge interactions from neutrino oscillation experiments

Science.gov (United States)

Kopp, Joachim; Welter, Johannes

2014-12-01

Sterile neutrino models with new gauge interactions in the sterile sector are phenomenologically interesting since they can lead to novel effects in neutrino oscillation experiments, in cosmology and in dark matter detectors, possibly even explaining some of the observed anomalies in these experiments. Here, we use data from neutrino oscillation experiments, in particular from MiniBooNE, MINOS and solar neutrino experiments, to constrain such models. We focus in particular on the case where the sterile sector gauge boson A ' couples also to Standard Model particles (for instance to the baryon number current) and thus induces a large Mikheyev-Smirnov-Wolfenstein potential. For eV-scale sterile neutrinos, we obtain strong constraints especially from MINOS, which restricts the strength of the new interaction to be less than ˜ 10 times that of the Standard Model weak interaction unless active-sterile neutrino mixing is very small (sin2 θ 24 ≲ 10-3). This rules out gauge forces large enough to affect short-baseline experiments like MiniBooNE and it imposes nontrivial constraints on signals from sterile neutrino scattering in dark matter experiments.

Steam separator-superheater with drawing of a fraction of the dried steam

International Nuclear Information System (INIS)

Bessouat, Roger; Marjollet, Jacques.

1976-01-01

This invention concerns a vertical separator-superheater of the steam from a high pressure expansion turbine before it is admitted to an expansion turbine at a lower pressure, by heat exchange with steam under a greater pressure, and drawing of a fraction of the dried steam before it is superheated. Such drawing off is necessary in the heat exchange systems of light water nuclear reactors. Its purpose is to provide a separator-superheater that provides an even flow of non superheated steam and a regular distribution of the steam to be superheated to the various superheating bundles, with a significantly uniform temperature of the casing, thereby preventing thermal stresses and ensuring a minimal pressure drop. The vertical separator-superheater of the invention is divided into several vertical sections comprising as from the central area, a separation area of the steam entrained water and a superheater area and at least one other vertical section with only a separation area of the steam entrained water [fr

HTCC - a heat transfer model for gas-steam mixtures

International Nuclear Information System (INIS)

Papadimitriou, P.

1983-01-01

The mathematical model HTCC (Heat Transfer Coefficient in Containment) has been developed for RALOC after a loss-of-coolant accident in order to determine the local heat transfer coefficients for transfer between the containment atmosphere and the walls of the reactor building. The model considers the current values of room and wall temperature, the concentration of steam and non-condensible gases, geometry data and those of fluid dynamics together with thermodynamic parameters and from these determines the heat transfer mechanisms due to convection, radiation and condensation. The HTCC is implemented in the RALOC program. Comparative analyses of computed temperature profiles, for HEDL Standard problems A and B on hydrogen distribution, and of computed temperature profiles determined during the heat-up phase in the CSE-A5 experiment show a good agreement with experimental data. (orig.) [de

Flow Instabilities and Main Steam Line Vibrations in a Pressurized Water Reactor

International Nuclear Information System (INIS)

Henriksson, Mats; Westin, Johan; Granhall, Tord; Andersson, Lars; Bjerke, Lars-Erik

2002-01-01

Severe vibrational problems occurred in the main steam system of a PWR nuclear power plant, about 18 months after a steam generator replacement had been carried out. The magnitude of the vibrations reached levels at which the operators had to reduce power in order to stay within the operating limits imposed by the nuclear inspectorate. To solve the problem the following analyses methods were employed: - Testing the influence on vibration level from different modes of plant operation; - Analyses of plant measurement data; - Calculations of: hydraulic behaviour of the system, structural dynamic behaviour of the system, flow at the steam generator outlet. Scale model testing of the steam generator outlet region. Hydraulic flow disturbances in the main steam system were measured using pressure and strain gauges, which made it possible to track individual pressure pulses propagating through the main steam system. Analyses showed that the pressure pulses causing the vibration originated from the vicinity of the steam generator outlet. By using computer codes for network fluid flow analyses the pressure pulses found in the measurement traces could be generated in calculations. Careful studies of the flow at the steam generator outlet region, using model testing in a 1:3 scale model as well as transient 3D CFD calculations, gave clear indications that flow separation occurred at the steam generator outlet nozzle and at the first bend. Finally, by substituting the outlet nozzle for a different design with a multi-port nozzle, the steam line vibration problem has been solved. (authors)

Male gametophytic sterility. 1 - Gametic sterilities and deletions in petunia

Energy Technology Data Exchange (ETDEWEB)

Cornu, A.; Maizonnier, D. (Station d' Amelioration des Plantes de l' I.N.R.A., Dijon (France))

1982-01-01

Terminal deletions induced by ionizing radiations in Petunia are not sexually transmitted. Cytogenetic study of plants with a heterozygous deletion and their progenies shows that this lack of transmission is accompanied by a gametic semi-sterility due to the fact that gametes carrying the deleted chromosome are not viable. The interest of such a male sterility with a gametophytic determinism for the study of sporophyte-gametophyte relationships is underlined.

Study on the characteristics of the supersonic steam injector

International Nuclear Information System (INIS)

Abe, Yutaka; Shibayama, Shunsuke

2014-01-01

Steam injector is a passive jet pump which operates without power source or rotating machinery and it has high heat transfer performance due to the direct-contact condensation of supersonic steam flow onto subcooled water jet. It has been considered to be applied to the passive safety system for the next-generation nuclear power plants. The objective of the present study is to clarify operating mechanisms of the steam injector and to determine the operating ranges. In this study, temperature and velocity distribution in the mixing nozzle as well as flow directional pressure distribution were measured. In addition, flow structure in whole of the injector was observed with high-speed video camera. It was confirmed that there were unsteady interfacial behavior in mixing nozzle which enhanced heat transfer between steam flow and water jet with calculation of heat transfer coefficient. Discharge pressure at diffuser was also estimated with a one-dimensional model proposed previously. Furthermore, it was clarified that steam flow did not condense completely in mixing nozzle and it was two-phase flow in throat and diffuser, which seemed to induce shock wave. From those results, several discussions and suggestions to develop a physical model which predicts the steam injectors operating characteristics are described in this paper

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....

Influence of recycling ratio on steam generator thermal recycling

International Nuclear Information System (INIS)

Bassel, W.S.; Rodrigues, V.G.

1989-01-01

A mathematical model was developed to simulate thermal performance of steam generator. The simulation was done with 3 control volumes. The coupled non-linear algebric equations, where the heat transfer was calculated with logarithmic meam temperature difference, was solved by iterative method. The developed model is suitable for calculation the parameters which effect the performance of steam generator. (author) [pt

Gamma-ray irradiation, autoclave and ethylene oxide sterilization to thermosetting polyurethane: sterilization to polyurethane

International Nuclear Information System (INIS)

Hirata, Noriko; Matsumoto, Ken-Ichi; Inishita, Takashi; Takenaka, Yoshinori; Suma, Yasunori; Shintani, Hideharu; National Inst. of Health Sciences, Tokyo

1995-01-01

Thermosetting polyurethane (PU) is widely used in a large variety of medical devices. 4,4'-methylenedianiline (MDA) was produced from PU by sterilization and it was studied for the relationship between urethane components or polymer characteristics and formation of MDA upon sterilization, using the commercially available dialyzers fabricated with different combination of isocyanate and polyol. We confirmed that the molecular-weight of polyol influenced the production of MDA upon sterilization. (author)

Sterile neutrinos in light of recent cosmological and oscillation data: a multi-flavor scheme approach

International Nuclear Information System (INIS)

Melchiorri, Alessandro; Mena, Olga; Sorel, Michel; Palomares-Ruiz, Sergio; Pascoli, Silvia; Slosar, Anze

2009-01-01

Light sterile neutrinos might mix with the active ones and be copiously produced in the early Universe. In the present paper, a detailed multi-flavor analysis of sterile neutrino production is performed. Making some justified approximations allows us to consider not only neutrino interactions with the primeval medium and neutrino coherence breaking effects, but also oscillation effects arising from the presence of three light (mostly-active) neutrino states mixed with two heavier (mostly-sterile) states. First, we emphasize the underlying physics via an analytical description of sterile neutrino abundances that is valid for cases with small mixing between active and sterile neutrinos. Then, we study in detail the phenomenology of (3+2) sterile neutrino models in light of short-baseline oscillation data, including the LSND and MiniBooNE results. Finally, by using the information provided by this analysis, we obtain the expected sterile neutrino cosmological abundances and then contrast them with the most recent available data from Cosmic Microwave Background and Large Scale Structure observations. We conclude that (3+2) models are significantly more disfavored by the internal inconsistencies between sterile neutrino interpretations of appearance and disappearance short-baseline data themselves, rather than by the used cosmological data

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 sin²2θ₂₄ ≤ 0.02 at m² ~ 0.3 eV², and the LSND and Mini

Materials Surfaces and sterility

Energy Technology Data Exchange (ETDEWEB)

Schmidt, R.

2001-04-01

A question of great interest in sterile and clean room technology is how can we devise a standard for the guarantee of sterility? Sterility is of widespread importance: it gives the life-time of our daily milk or yogurt, dominates the nature of food packing, and determines the feasibility of the miniaturization of biotechnology plants. All these phenomena are based on the principle of bioadhesion. Bioadhesion is also the basis of the biomimetic material technologies, like the attachment of selected protein layers that can be used for nanomasking. (orig.)

The testing of a steam-water separating device used for vertical steam generators

International Nuclear Information System (INIS)

Ding Xunshen; Cui Baoyuan; Xue Yunkui; Liu Shixun

1989-01-01

The air-water screening tests of a steam-water separating device used for vertical steam generators at low pressure are introduced. The article puts emphasis on the qualification test of the steam-water separating device at hot conditions in a high temperature and pressure water test rig. The performance of the comprehensive test of the steam-water separating device indicates that the humidity of the steam at the drier exit is much less than the specified amount of 0.25%

Packaging materials for plasma sterilization with the flowing afterglow of an N{sub 2}-O{sub 2} discharge: damage assessment and inactivation efficiency of enclosed bacterial spores

Energy Technology Data Exchange (ETDEWEB)

Levif, P; Moisan, M; Soum-Glaude, A [Groupe de Physique des Plasmas, Universite de Montreal, CP 6128, Succursale Centre-Ville, Montreal H3C 3J7, Quebec (Canada); Seguin, J; Barbeau, J, E-mail: michel.moisan@umontreal.ca [Faculte de Medecine Dentaire, Laboratoire de Controle des Infections, Universite de Montreal, CP 6128, Montreal H3C 3J7, Quebec (Canada)

2011-10-12

In conventional sterilization methods (steam, ozone, gaseous chemicals), after their proper cleaning, medical devices are wrapped/enclosed in adequate packaging materials, then closed/sealed before initiating the sterilization process: these packaging materials thus need to be porous. Gaseous plasma sterilization being still under development, evaluation and comparison of packaging materials have not yet been reported in the literature. To this end, we have subjected various porous packagings used with conventional sterilization systems to the N{sub 2}-O{sub 2} flowing afterglow and also a non-porous one to evaluate and compare their characteristics towards the inactivation of B. atrophaeus endospores deposited on a Petri dish and enclosed in such packagings. Because the sterilization process with the N{sub 2}-O{sub 2} discharge afterglow is conducted under reduced-pressure conditions, non-porous pouches can be sealed only after returning to atmospheric pressure. All the tests were therefore conducted with one end of the packaging freely opened, post-sealing being required. The features of these packaging materials, namely mass loss, resistance, toxicity to human cells as well as some characteristics specific to the plasma method used such as ultraviolet transparency, were examined before and after exposure to the flowing afterglow. All of our results show that the non-porous packaging considered is much more suitable than the conventionally used porous ones as far as ensuring an efficient and low-damage sterilization process with an N{sub 2}-O{sub 2} plasma-afterglow is concerned.

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.

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)

1996-12-31

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.

Strategies for steam

International Nuclear Information System (INIS)

Hennagir, T.

1996-01-01

This article is a review of worldwide developments in the steam turbine and heat recovery steam generator markets. The Far East is driving the market in HRSGs, while China is driving the market in orders placed for steam turbine prime movers. The efforts of several major suppliers are discussed, with brief technical details being provided for several projects

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)

Dynamic analysis of CHASNUPP steam generator structure during shipping

International Nuclear Information System (INIS)

Han Liangbi; Xu Jinkang; Zhou Meiwu; He Yinbiao

1998-07-01

The dynamic analysis of CHASNUPP steam generator during shipping is described, including the simplified mathematical model, acceleration power spectrum of ocean wave induced random vibration, the dynamic analysis of steam generator structure under random loading, the applied computer code and calculated results

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)

Heat transfer characteristics of horizontal steam generators under natural circulation conditions

International Nuclear Information System (INIS)

Hyvaerinen, J.

1996-01-01

This paper deals with the heat transfer characteristics of horizontal steam generators, particularly under natural circulation (decay heat removal) conditions on the primary side. Special emphasis is on the inherent features of horizontal steam generator behaviour. A mathematical model of the horizontal steam generator primary side is developed and qualitative results are obtained analytically. A computer code, called HSG, is developed to solve the model numerically, and its predictions are compared with experimental data. The code is employed to obtain for VVER 440 steam generators quantitative results concerning the dependence of primary-to-secondary heat transfer efficiency on the primary side flow rate, temperature and secondary level. It turns out that the depletion of the secondary inventory leads to an inherent limitation of the decay energy removal in VVER steam generators. The limitation arises as a consequence of the steam generator tube bundle geometry. As an example, it is shown that the grace period associated with pressurizer safety valve opening during a station black-out is 2 1/2-3 hours instead of the 5-6 hours reported in several earlier studies. (However, the change in core heat-up timing is much less-about 1 h at most.) The heat transfer limitation explains the fact that, in the Greifswald VVER 440 station black-out accident in 1975, the steam generators never boiled dry. In addition, the stability of single-phase natural circulation is discussed and insights on the modelling of horizontal steam generators with general-purpose thermal-hydraulic system codes are also presented. (orig.)

Modeling steam pressure under martian lava flows

Science.gov (United States)

Dundas, Colin M.; Keszthelyi, Laszlo P.

2013-01-01

Rootless cones on Mars are a valuable indicator of past interactions between lava and water. However, the details of the lava–water interactions are not fully understood, limiting the ability to use these features to infer new information about past water on Mars. We have developed a model for the pressurization of a dry layer of porous regolith by melting and boiling ground ice in the shallow subsurface. This model builds on previous models of lava cooling and melting of subsurface ice. We find that for reasonable regolith properties and ice depths of decimeters, explosive pressures can be reached. However, the energy stored within such lags is insufficient to excavate thick flows unless they draw steam from a broader region than the local eruption site. These results indicate that lag pressurization can drive rootless cone formation under favorable circumstances, but in other instances molten fuel–coolant interactions are probably required. We use the model results to consider a range of scenarios for rootless cone formation in Athabasca Valles. Pressure buildup by melting and boiling ice under a desiccated lag is possible in some locations, consistent with the expected distribution of ice implanted from atmospheric water vapor. However, it is uncertain whether such ice has existed in the vicinity of Athabasca Valles in recent history. Plausible alternative sources include surface snow or an aqueous flood shortly before the emplacement of the lava flow.

Fragmentation of low-melting metals by collapsing steam bubbles

International Nuclear Information System (INIS)

Benz, R.

1979-08-01

When a hot melt meets a vaporable liquid of lower temperature, explosive vaporisation of the cooler liquid may be the result. This is called a steam explosion if a substantial amount of thermal energy is converted into mechanical energy. One important step in understanding about steam explosions is to explain the surface increase of the hot melt. There are several competing fragmentation hypotheses, but so far there has been no model to describe fragmentation criteria as well as the time curve of surface increase on the basis of physical processes. An overall model is now given for one of the possible fragmentation mechanisms, i.e. the division of the melt by collapsing steam bubbles. The model estimates the surface increase of the melt on the basis of heavy supercooled boiling, the heat transfer connected with it, the transfer of mechanical energy during steam bubble collapse, and the solidification of the melt. The results of the calculations have shown that basic experimental observations, e.g. time and extent of fragmentation, are well presented in the model with regard to their order of magnitude. The model presents a qualitatively correct description of the effects of important influencing factors, e.g. supercooling of the coolant or initial temperature of the melt. (orig.) [de

Steam CFD simulation of injection in suppression pool

International Nuclear Information System (INIS)

Naveen Samad, A.M.; Ghosh, Sumana

2015-01-01

Boiling water reactor (BWR) is one of the common types of electricity generating nuclear reactor. Suppression pool system is a major component of the BWR which has to be designed efficiently for the safe operations. During some accidents like Loss of Coolant Accident (LOCA) large amount of steam are injected to the pressure suppression system resulting in increase in temperature of the pool and thereby increasing the pressure. The present work discuss about the Computational Fluid Dynamics (CFD) simulation of steam injected to the wet well of BWR through the blow down pipes and there by investigating the hydrodynamic and thermal characteristics of the system. The simulations were carried out for three different steam injection velocities. The numerical simulations were performed with ANSYS FLUENT using multiphase 3D Volume of Fluid (VOF) model and k-ε model was adopted for modelling turbulence flow. (author)

The economics of race and eugenic sterilization in North Carolina: 1958-1968.

Science.gov (United States)

Price, Gregory N; Darity, William A

2010-07-01

Theoretical justifications for state-sanctioned sterilization of individuals provided by Irving Fisher rationalized its racialization on grounds that certain non-white racial groups, particularly blacks due to their dysgenic biological and behavioral traits, retarded economic growth and should be bred out of existence. Fisher's rationale suggests that national or state level eugenic policies that sterilized the so-called biological and genetically unfit could have been racist in both design and effect by disproportionately targeting black Americans. We empirically explore this with data on eugenic sterilizations in the State of North Carolina between 1958 and 1968. Count data parameter estimates from a cross-county population allocation model of sterilization reveal that the probability of non-institutional and total sterilizations increased with a county's black population share-an effect not found for any other racial group in the population. Our results suggest that in North Carolina, eugenic sterilization policies were racially biased and genocidal. 2010 Elsevier B.V. All rights reserved.

Sterile neutrinos and indirect dark matter searches in IceCube

Science.gov (United States)

Argüelles, Carlos A.; Kopp, Joachim

2012-07-01

If light sterile neutrinos exist and mix with the active neutrino flavors, this mixing will affect the propagation of high-energy neutrinos from dark matter annihilation in the Sun. In particular, new Mikheyev-Smirnov-Wolfenstein resonances can occur, leading to almost complete conversion of some active neutrino flavors into sterile states. We demonstrate how this can weaken IceCube limits on neutrino capture and annihilation in the Sun and how potential future conflicts between IceCube constraints and direct detection or collider data might be resolved by invoking sterile neutrinos. We also point out that, if the dark matter-nucleon scattering cross section and the allowed annihilation channels are precisely measured in direct detection and collider experiments in the future, IceCube can be used to constrain sterile neutrino models using neutrinos from the dark matter annihilation.

Thermodynamic performance analysis and algorithm model of multi-pressure heat recovery steam generators (HRSG) based on heat exchangers layout