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Sample records for enriched gadolinia burnable

  1. A feasibility study for the application of enriched gadolinia burnable absorber rods in nuclear core design

    International Nuclear Information System (INIS)

    Lee, Chung Chan; Zee, Sung Quun; Kim, Kang Seog; Song, Jae Seung

    2000-12-01

    An analysis model using MICBURN-3/CASMO-3 is established for the enriched gadolinia burnable absorber rods. A homogenized cross section editing code, PROLOG, is modified so that it can handle such a fuel assembly that includes two different types of gadolinia rods. Study shows that Gd-155 and Gd-157 are almost same in suppressing the excess reactivity and it is recommended to enrich both odd number isotopes, Gd-155 and Gd-157. It is estimated that the cycle length increases by 2 days if enriched gadolinia rods are used in the commercial nuclear power plant such as YGN-3 of which the cycle length is assumed 2 years. For the advanced integral reactor SMART in which ultra long cycle length and soluble boron-free operation concept is applied, natural gadolinia burnable absorber rods fail to control the excess reactivity. On the other hand, enriched gadolinia rods are successful in controling the excess reactivity. To minimize power peakings, various placements of gadolinia rods are tested. Also initial reactivity holddown and gadolinia burnout time are parametrized with respect to the number of gadolinia rods and gadolinia weight fractions

  2. A study on the nuclear characteristics of enriched gadolinia burnable absorber rods; the first year (2000) report

    International Nuclear Information System (INIS)

    Zee, Sung Quun; Lee, C.C.; Song, J. S.; Cho, B. O.; Joo, H. G.; Park, S. Y.; Kim, H. Y.; Cho, J. Y.; Kim, K. S.

    2001-04-01

    An analysis model using MICBURN-3/CASMO-3 is established for the enriched gadolinia burnable absorber rods. A homogenized cross section editing code, PROLOG, is modified so that it can handle such a fuel assembly that includes two different types of gadolinia rods. Study shows that Gd-155 and Gd-157 are almost same in suppressing the excess reactivity and it is recommended to enrich both odd number isotopes, Gd-155 and Gd-157. It is estimated that the cycle length increases by 2 days if enriched gadolinia rods are used in the commercial nuclear power plant such as YGN-3 of which the cycle length is assumed 2 years. For the advanced integral reactor SMART in which ultra long cycle length and soluble boron-free operation concept is applied, natural gadolinia burnable absorber rods fail to control the excess reactivity. On the other hand, enriched gadolinia rods are successful in controling the excess reactivity. To minimize power peakings, various placements of gadolinia rods are tested. Also initial reactivity holddown and gadolinia burnout time are parametrized with respect to the number of gadolinia rods and gadolinia weight fractions

  3. PWR fuel of high enrichment with erbia and enriched gadolinia

    International Nuclear Information System (INIS)

    Bejmer, Klaes-Håkan; Malm, Christian

    2011-01-01

    Today standard PWR fuel is licensed for operation up to 65-70 MWd/kgU, which in most cases corresponds to an enrichment of more than 5 w/o "2"3"5U. Due to criticality safety reason of storage and transportation, only fuel up to 5 w/o "2"3"5U enrichment is so far used. New fuel storage installations and transportation casks are necessary investments before the reactivity level of the fresh fuel can be significantly increased. These investments and corresponding licensing work takes time, and in the meantime a solution that requires burnable poisons in all pellets of the fresh high-enriched fuel might be used. By using very small amounts of burnable absorber in every pellet the initial reactivity can be reduced to today's levels. This study presents core calculations with fuel assemblies enriched to almost 6 w/o "2"3"5U mixed with a small amount of erbia. Some of the assemblies also contain gadolinia. The results are compared to a reference case containing assemblies with 4.95 w/o "2"3"5U without erbia, utilizing only gadolinia as burnable poison. The comparison shows that the number of fresh fuel assemblies can be reduced by 21% (which increases the batch burnup by 24%) by utilizing the erbia fuel concept. However, increased cost of uranium due to higher enrichment is not fully compensated for by the cost gain due to the reduction of the number assemblies. Hence, the fuel cycle cost becomes slightly higher for the high enrichment erbia case than for the reference case. (author)

  4. Experience in the use of low concentration gadolinia as a PWR fuel burnable absorber

    International Nuclear Information System (INIS)

    Mildrum, C.M.; Segovia, M.A.

    2001-01-01

    A description is provided of the low concentration gad design being used in the Spanish 3-loop 17 x 17 fueled PWR's. This design uses a relatively small number of high concentration gadolinia fuel rods (6 and 8 w/o Gd 2 O 3 ) with a large number of low concentration gad rods (2 w/o Gd 2 O 3 ). The 2 w/o gad rods substitute, in part, the high concentration gad rods, thereby helping reduce the end of cycle reactivity penalty from the residual absorption in the gadolinium. The low concentration gad design is advantageous for long cycles (18+ months) and plant up-rating scenarios in that the soluble boron concentration increases that would otherwise result for these situations are avoided. These boron concentration increases could have potentially adverse effects on the plant, since the moderator temperature coefficient (MTC) is made less negative, the effectiveness of the boron shutdown safety systems is reduced, and the safety margins are eroded for some accidents, such as for boron dilution events. These increases in the boron concentration would also require the plant to operate at higher lithium (Li) concentrations in the coolant in order to maintain the pH level at the desired value. Operation at the higher Li concentrations is undesirable because of the concerns over the potential impact on the fuel assembly material performance (e.g., crud and corrosion). This paper also reviews the APA (Alpha/Phoenix-P/ANC) nuclear design code system performance for the low concentration gad design. The design system performance for the reload cores that have or are employing this design has been completely satisfactory. The performance and accuracy of the nuclear design methodology is found to be as good for this design as for the reload cores that use exclusively high gad concentrations, or those that use WABA's - the discrete burnable absorber (BA) used prior to its substitution for gadolinium. (authors)

  5. Gadolinia experience and design for PWR fuel cycles

    International Nuclear Information System (INIS)

    Stephenson, L. C.

    2000-01-01

    The purpose of this paper is to describe Siemens Power Corporation's (SPC) current experience with the burnable absorber gadolinia in PWR fuel assemblies, including optimized features of SPC's PWR gadolinia designs, and comparisons with other burnable absorbers. Siemens is the world leader in PWR gadolinia experience. More than 5,900 Siemens PWR gadolinia-bearing fuel assemblies have been irradiated. The use of gadolinia-bearing fuel provides significant flexibility in fuel cycle designs, allows for low radial leakage fuel management and extended operating cycles, and reduces BOC (beginning-of-cycle) soluble boron concentrations. The optimized use of an integral burnable neutron absorber is a design feature which provides improved economic performance for PWR fuel assemblies. This paper includes a comparison between three different types of integral burnable absorbers: gadolinia, Zirconium diboride and erbia. Fuel cycle design studies performed by Siemens have shown that the enrichment requirements for 18-24 month fuel cycles utilizing gadolinia or zirconium diboride integral fuel burnable absorbers can be approximately the same. Although a typical gadolinia residual penalty for a cycle design of this length is as low as 0.02-0.03 wt% U-235, the design flexibility of gadolinia allows for very aggressive low-leakage core loading plans which reduces the enrichment requirements for gadolinia-bearing fuel. SPC has optimized its use of gadolinia in PWR fuel cycles. Typically, low (2-4) weight percent Gd 2 O 3 is used for beginning to middle of cycle reactivity hold down as well as soluble boron concentration holddown at BOC. Higher concentrations of Gd 2 O 3 , such as 6 and 8 wt%, are used to control power peaking in assemblies later in the cycle. SPC has developed core strategies that maximize the use of lower gadolinia concentrations which significantly reduces the gadolinia residual reactivity penalty. This optimization includes minimizing the number of rods with

  6. Critical experiments on minimal-content gadolinia for above-5wt% enrichment fuels in Toshiba NCA

    International Nuclear Information System (INIS)

    Kikuchi, Tsukasa; Watanabe, Shouichi; Yoshioka, Kenichi; Mitsuhashi, Ishi; Kumanomido, Hironori; Sugahara, Satoshi; Hiraiwa, Kouji

    2009-01-01

    A concept of 'minimal-content gadolinia' with a content of less than several hundred ppm mixed in the 'above-5wt% enrichment UO 2 fuel' for super high burnup is proposed for ensuring the criticality safety in the UO 2 fuel fabrication facility for light water reactors (LWRs) without increase in investment cost. Required gadolinia contents calculated were from 53 to 305 ppm for enrichments of UO 2 powders for boiling water reactor (BWR) fuel from 6 to 10 wt%. It is expected that the minimal-content gadolinia yields an acceptable reactivity suppression at the beginning of operating cycle and no reactivity penalty at the end of operating cycle due to no residual gadolinium. A series of critical experiments were carried out in the Toshiba Nuclear Critical Assembly (NCA). Reactivity effects of the gadolinia were measured to clarify the nuclear characteristics, and the measured values and the calculated values agreed within 5%. (author)

  7. Experience in the use of low concentration gadolinia as a PWR fuel burnable absorber

    International Nuclear Information System (INIS)

    Mildrum, C.M.; Segovia, M.A.

    2001-01-01

    A description is provided of the low concentration gad design being used in the Spanish 3-loop 17 x 17 fueled PWR's. This design uses a relatively small number of high concentration gadolinia fuel rods (6 and 8 w/o Gd2O3) with a large number of low concentration gad rods (2 w/o Gd2O3). The 2 w/o gad rods substitute, in part, the high concentration gad rods, thereby helping reduce the end of cycle reactivity penalty from the residual absorption in the gadolinium. The low concentration gad design is advantageous for long cycles (more than 18 months) and plant up-rating scenarios in that the soluble boron concentration increases that would otherwise result for these situations are avoided. These boron concentration increases could have potentially adverse effects on the plant, since the moderator temperature coefficient (MTC) is made less negative, the effectiveness of the boron shutdown safety systems is reduced, and the safety margins are eroded for some accidents, such as for boron dilution events. This paper also reviews the APA nuclear design code system performance for the low concentration gad design. (author)

  8. Modification of Japanese first nuclear ship reactor for a regional energy supply system using gadolinia as a burnable poison

    International Nuclear Information System (INIS)

    Sato, Kotaro; Shimazu, Yoichiro; Narabayashi, Tadashi; Tsuji, Masashi

    2009-01-01

    In our laboratory, a small regional energy supply system which uses a small nuclear reactor has been studied for a long time. This system could supply not only heat but also electricity. Heat could be used for hot-water supply, a heating system of a house, melting snow and so on. In this point, this system seems to be useful for the places like northern part of Japan where it snows in winter. This reactor is based on Nuclear Ship Mutsu which was developed as the first nuclear ship of Japan about 40 years ago. It has several advantages for a small reactor. For example, its moderator temperature coefficient is always to be deeply negative because boric acid solution is not used in moderator and coolant. This can lead to a self-controlled operation without control rod maneuvering for load change. But some modifications have been performed in order to satisfy requirements such as (1) longer core life without refueling and reshuffling, (2) reactivity adjustment for load change without control rods or soluble boron, (3) simpler operations for load changes and (4) ultimate safety with sufficient passive capability. In our previous study, we confirmed the core based on Mutsu core had longer core life (about 10 years) using high uranium enrichment fuel (more than 5wt%) and current 17x17 fuel assemblies. We also confirmed excess reactivity during the cycle could be suppressed using combination of erbium oxide (Er 2 O 3 ) and gadolinium oxide (Gd 2 O 3 ) as burnable poisons. Er 2 O 3 has advantages such that criticality safety can be kept even if uranium enrichment is more than 5wt% and burnup characteristics of the core can be gradual. But at this time there are 2 problems to apply for the core using Er 2 O 3 in Japan. First problem is that more than 5wt% enrichment fuel is not yet accepted in Japan. Second problem is that there are no experiences of using Er 2 O 3 in commercial reactors in Japan. Considering these problems, we have to modify the design of the core, using

  9. The burnable poisons utilization for fissile enriched CANDU fuel bundle

    Energy Technology Data Exchange (ETDEWEB)

    Serghiuta, D; Nainer, O [Team 3 Solutions, Don Mills, ON (Canada)

    1996-12-31

    Utilization of burnable poison for the fissile enriched fueled CANDU 6 Mk1 core is investigated. The main incentives for this analysis are the reduction of void reactivity effects, the maximization of the fissile content of fresh fuel bundles, and the achievement of better power shape control, in order to preserve the power envelope of the standard 37 rod fuel bundle. The latter allows also the preservation of construction parameters of the standard core (for example: number and location of reactivity devices). It also permits the use of regular shift fueling schemes. The paper makes analyses of MOX weapons-grade plutonium and 1.2% SEU fueled CANDU 6 Mk 1 cores. (author). 6 refs., 4 tabs., 10 figs.

  10. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Louise G., E-mail: evanslg@ornl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Swinhoe, Martyn T.; Menlove, Howard O. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Schwalbach, Peter; Baere, Paul De [European Commission, Euratom Safeguards Office (Luxembourg); Browne, Michael C. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

    2013-11-21

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd{sub 2}O{sub 3}) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available {sup 241}AmLi (α,n) interrogation source strength of 5.7×10{sup 4} s{sup −1}. Furthermore, the calibration range of the new collar has been extended to verify {sup 235}U content in variable PWR fuel

  11. A new fast neutron collar for safeguards inspection measurements of fresh low enriched uranium fuel assemblies containing burnable poison rods

    International Nuclear Information System (INIS)

    Evans, Louise G.; Swinhoe, Martyn T.; Menlove, Howard O.; Schwalbach, Peter; Baere, Paul De; Browne, Michael C.

    2013-01-01

    Safeguards inspection measurements must be performed in a timely manner in order to detect the diversion of significant quantities of nuclear material. A shorter measurement time can increase the number of items that a nuclear safeguards inspector can reliably measure during a period of access to a nuclear facility. In turn, this improves the reliability of the acquired statistical sample, which is used to inform decisions regarding compliance. Safeguards inspection measurements should also maintain independence from facility operator declarations. Existing neutron collars employ thermal neutron interrogation for safeguards inspection measurements of fresh fuel assemblies. A new fast neutron collar has been developed for safeguards inspection measurements of fresh low-enriched uranium (LEU) fuel assemblies containing gadolinia (Gd 2 O 3 ) burnable poison rods. The Euratom Fast Collar (EFC) was designed with high neutron detection efficiency to make a fast (Cd) mode measurement viable whilst meeting the high counting precision and short assay time requirements of the Euratom safeguards inspectorate. A fast mode measurement reduces the instrument sensitivity to burnable poison rod content and therefore reduces the applied poison correction, consequently reducing the dependence on the operator declaration of the poison content within an assembly. The EFC non-destructive assay (NDA) of typical modern European pressurized water reactor (PWR) fresh fuel assembly designs have been simulated using Monte Carlo N-particle extended transport code (MCNPX) simulations. Simulations predict that the EFC can achieve 2% relative statistical uncertainty on the doubles neutron counting rate for a fast mode measurement in an assay time of 600 s (10 min) with the available 241 AmLi (α,n) interrogation source strength of 5.7×10 4 s −1 . Furthermore, the calibration range of the new collar has been extended to verify 235 U content in variable PWR fuel designs in the presence of up to

  12. Heterogeneous burnable poisons. Sinterability study in oxidizing atmosphere of alumina-gadolinia and alumina-boron carbide compounds

    International Nuclear Information System (INIS)

    Agueda, H.C.; Leiva, S.F.; Russo, D.O.

    1990-01-01

    Solid burnable poisons are used in reactors cooled by pressure light water (PLWR) with the purpose of controlling initial reactivity in the first reactor's core. The burnable poisons may be uniformly mixed with the fuel -known as 'homogeneous' poisons-; or constituting separate elements -known as heterogeneous poisons-. The purpose of this work is to present the results of two sinterability studies, performed on Al 2 O 3 -Gd 2 O 3 and Al 2 O 3 -B 4 C, where alumina acts as inert matrix, storing the absorbing elements as Gd 2 O 3 or B 4 C. The elements were sintered at an air atmosphere and additives permitting the obtention of a greater density alumina were tested at lower temperatures than the characteristic for this material, in order to determine its compatibility with the materials dealt with herein. (Author) [es

  13. Optimization of BWR fuel lattice enrichment and gadolinia distribution using genetic algorithms and knowledge

    International Nuclear Information System (INIS)

    Martin-del-Campo, Cecilia; Francois, Juan Luis; Carmona, Roberto; Oropeza, Ivonne P.

    2007-01-01

    An optimization methodology based on the Genetic Algorithms (GA) method was developed for the design of radial enrichment and gadolinia distributions for boiling water reactor (BWR) fuel lattices. The optimization algorithm was linked to the HELIOS code to evaluate the neutronic parameters included in the objective function. The goal is to search for a fuel lattice with the lowest average enrichment, which satisfy a reactivity target, a local power peaking factor (PPF), lower than a limit value, and an average gadolinia concentration target. The methodology was applied to the design of a 10 x 10 fuel lattice, which can be used in fuel assemblies currently used in the two BWRs operating at Mexico. The optimization process showed an excellent performance because it found forty lattice designs in which the worst one has a better neutronic performance than the reference lattice design. The main contribution of this study is the development of an efficient procedure for BWR fuel lattice design, using GA with an objective function (OF) which saves computing time because it does not require lattice burnup calculations

  14. Optimization of PWR fuel assembly radial enrichment and burnable poison location based on adaptive simulated annealing

    International Nuclear Information System (INIS)

    Rogers, Timothy; Ragusa, Jean; Schultz, Stephen; St Clair, Robert

    2009-01-01

    The focus of this paper is to present a concurrent optimization scheme for the radial pin enrichment and burnable poison location in PWR fuel assemblies. The methodology is based on the Adaptive Simulated Annealing (ASA) technique, coupled with a neutron lattice physics code to update the cost function values. In this work, the variations in the pin U-235 enrichment are variables to be optimized radially, i.e., pin by pin. We consider the optimization of two categories of fuel assemblies, with and without Gadolinium burnable poison pins. When burnable poisons are present, both the radial distribution of enrichment and the poison locations are variables in the optimization process. Results for 15 x 15 PWR fuel assembly designs are provided.

  15. Optimization of axial enrichment and gadolinia distributions for BWR fuel under control rod programming, (2)

    International Nuclear Information System (INIS)

    Hida, Kazuki; Yoshioka, Ritsuo

    1992-01-01

    A method has been developed for optimizing the axial enrichment and gadolinia distributions for the reload BWR fuel under control rod programming. The problem was to minimize the enrichment requirement subject to the criticality and axial power peaking constraints. The optimization technique was based on the successive linear programming method, each linear programming problem being solved by a goal programming algorithm. A rapid and practically accurate core neutronics model, named the modified one-dimensional core model, was developed to describe the batch-averaged burnup behavior of the reload fuel. A core burnup simulation algorithm, employing a burnup-power-void iteration, was also developed to calculate the rigorous equilibrium cycle performance. This method was applied to the optimization of axial two- and 24-region fuels for demonstrative purposes. The optimal solutions for both fuels have proved the optimality of what is called burnup shape optimization spectral shift. For the two-region fuel with a practical power peaking of 1.4, the enrichment distribution was nearly uniform, because a bottom-peaked burnup shape flattens the axial power shape. Optimization of the 24-region fuel has shown a potential improvement in BWR fuel cycle economics, which will guide future advancement in BWR fuel designs. (author)

  16. Neutronic analysis of a fuel element with variations in fuel enrichment and burnable poison

    Energy Technology Data Exchange (ETDEWEB)

    Faria, Rochkhudson B. de; Martins, Felipe; Velasquez, Carlos E.; Cardoso, Fabiano; Fortini, Angela; Pereira, Claubia, E-mail: rochkdefaria@yahoo.com.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    In this work, the goal was to evaluate the neutronic behavior during the fuel burnup changing the amount of burnable poison and fuel enrichment. For these analyses, it was used a 17 x 17 PWR fuel element, simulated using the 238 groups library cross-section collapsed from ENDF/BVII.0 and TRITON module of SCALE 6.0 code system. The results confirmed the effective action of the burnable poison in the criticality control, especially at Beginning Of Cycle (BOC) and in the burnup kinetics, because at the end of the fuel cycle there was a minimal residual amount of neutron absorbers ({sup 155}Gd and {sup 157}Gd), as expected. At the end of the cycle, the fuel element was still critical in all simulated situations, indicating the possibility of extending the fuel burn. (author)

  17. Volume Reduction of Decommissioning Burnable Waste with Oxygen Enrich Incinerator

    Energy Technology Data Exchange (ETDEWEB)

    Min, B. Y.; Yang, D. S.; Lee, K. W.; Choi, J. W. [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The incineration technology is an effective treatment method that contains hazardous chemicals as well as radioactive contamination. The volume reduction of the combustible wastes through the incineration technologies has merits from the view point of a decrease in the amount of waste to be disposed of resulting in a reduction of the disposal cost. Incineration is generally accepted as a method of reducing the volume of radioactive waste. The incineration technology is an effective treatment method that contains hazardous chemicals as well as radioactive contamination. This paper covers the general facility operation of an oxygen-enriched incinerator for the treatment of decommissioning wastes generated from a decommissioning project. The combustible wastes have been treated by the utilization of incinerator the capacity of the average 20 kg/hr. The decommissioning combustible waste of about 31 tons has been treated using Oxygen Enriched incinerator by at the end of 2016. The off-gas flow and temperature were maintained constant or within the desired range. The measured gases and particulate materials in the stack were considerably below the regulatory limits.

  18. Volume Reduction of Decommissioning Burnable Waste with Oxygen Enrich Incinerator

    International Nuclear Information System (INIS)

    Min, B. Y.; Yang, D. S.; Lee, K. W.; Choi, J. W.

    2016-01-01

    The incineration technology is an effective treatment method that contains hazardous chemicals as well as radioactive contamination. The volume reduction of the combustible wastes through the incineration technologies has merits from the view point of a decrease in the amount of waste to be disposed of resulting in a reduction of the disposal cost. Incineration is generally accepted as a method of reducing the volume of radioactive waste. The incineration technology is an effective treatment method that contains hazardous chemicals as well as radioactive contamination. This paper covers the general facility operation of an oxygen-enriched incinerator for the treatment of decommissioning wastes generated from a decommissioning project. The combustible wastes have been treated by the utilization of incinerator the capacity of the average 20 kg/hr. The decommissioning combustible waste of about 31 tons has been treated using Oxygen Enriched incinerator by at the end of 2016. The off-gas flow and temperature were maintained constant or within the desired range. The measured gases and particulate materials in the stack were considerably below the regulatory limits.

  19. Comparison of heuristic optimization techniques for the enrichment and gadolinia distribution in BWR fuel lattices and decision analysis

    International Nuclear Information System (INIS)

    Castillo, Alejandro; Martín-del-Campo, Cecilia; Montes-Tadeo, José-Luis; François, Juan-Luis; Ortiz-Servin, Juan-José; Perusquía-del-Cueto, Raúl

    2014-01-01

    Highlights: • Different metaheuristic optimization techniques were compared. • The optimal enrichment and gadolinia distribution in a BWR fuel lattice was studied. • A decision making tool based on the Position Vector of Minimum Regret was applied. • Similar results were found for the different optimization techniques. - Abstract: In the present study a comparison of the performance of five heuristic techniques for optimization of combinatorial problems is shown. The techniques are: Ant Colony System, Artificial Neural Networks, Genetic Algorithms, Greedy Search and a hybrid of Path Relinking and Scatter Search. They were applied to obtain an “optimal” enrichment and gadolinia distribution in a fuel lattice of a boiling water reactor. All techniques used the same objective function for qualifying the different distributions created during the optimization process as well as the same initial conditions and restrictions. The parameters included in the objective function are the k-infinite multiplication factor, the maximum local power peaking factor, the average enrichment and the average gadolinia concentration of the lattice. The CASMO-4 code was used to obtain the neutronic parameters. The criteria for qualifying the optimization techniques include also the evaluation of the best lattice with burnup and the number of evaluations of the objective function needed to obtain the best solution. In conclusion all techniques obtain similar results, but there are methods that found better solutions faster than others. A decision analysis tool based on the Position Vector of Minimum Regret was applied to aggregate the criteria in order to rank the solutions according to three functions: neutronic grade at 0 burnup, neutronic grade with burnup and global cost which aggregates the computing time in the decision. According to the results Greedy Search found the best lattice in terms of the neutronic grade at 0 burnup and also with burnup. However, Greedy Search is

  20. Radial power distribution shaping within a PWR fuel assembly utilizing asymmetrically loaded gadolinia-bearing fuel pins

    International Nuclear Information System (INIS)

    Stone, I.Z.

    1992-01-01

    As in-core fuel management designs evolve to meet the demands of increasing energy output, more innovative methods are developed to maintain power peaking within acceptable thermal margin limits. In-core fuel management staff must utilize various loading pattern strategies such as cross-core movement of fuel assemblies, multibatch enrichment schemes, and burnable absorbers as the primary means of controlling the radial power distribution. The utilization of fresh asymmetrically loaded gadolinia-bearing assemblies as a fuel management tool provides an additional means of controlling the radial power distribution. At Siemens Nuclear Power Corporation (SNP), fresh fuel assemblies fabricated with asymmetrically loaded gadolinia-bearing fuel rods have been used successfully for several cycles of reactor operation. Asymmetric assemblies are neutronically modeled using the same tools and models that SNP uses to model symmetrically loaded gadolinia-bearing fuel assemblies. The CASMO-2E code is used to produce the homogenized macroscopic assembly cross sections for the nodal core simulator. Optimum fuel pin locations within the asymmetrical assembly are determined using the pin-by-pin PDQ7 assembly core model for each new assembly design. The optimum pin location is determined by the rod loading that minimizes the peak-to-average pin power

  1. Measurement of reactivity worths of burnable poison rods in enriched uranium graphite-moderated core simulated to high temperature gas cooled reactor

    International Nuclear Information System (INIS)

    Akino, Fujiyoshi; Takeuchi, Motoyoshi; Kitadate, Kenji; Yoshifuji, Hisashi; Kaneko, Yoshihiko

    1980-11-01

    As the core design for the Experimental Very High Temperature Gas Cooled Reactor progresses, evaluation of design precision has become increasingly important. For a high precision design, it is required to have adequate group constants based on accurate nuclear data, as well as calculation methods properly describing the physical behavior of neutrons. We, therefore, assembled a simulation core for VHTR, SHE-14, using a graphite-moderated 20%-enriched uranium Semi-Homogeneous Experimental Critical Facility (SHE), and obtained useful experimental data in evaluating the design precision. The VHTR is designed to accommodate burnable poison and control rods for reactivity compensation. Accordingly, the experimental burnable poison rods which are similar to those to be used in the experimental reactor were prepared, and their reactivity values were measured in the SHE-14 core. One to three rods of the above experimental burnable poison rods were inserted into the central column of the SHE-14 core, and the reactivity values were measured by the period and fuel rod substitution method. The results of the measurements have clearly shown that due to the self-shielding effect of B 4 C particles the reactivity value decreases with increasing particle diameter. For the particle diameter, the reactivity value is found to increase linearly with the logarithm of boron content. The measured values and those calculated are found to agree with each other within 5%. These results indicate that the reactivity of the burnable poison rod can be estimated fairly accurately by taking into account the self-shielding effect of B 4 C particles and the heterogeneity of the lattice cell. (author)

  2. An evaluation of nuclear design characteristics of duplex burnable poison rods for extended cycle core

    International Nuclear Information System (INIS)

    Lee, D. J.; Kim, M. H.; Song, K. W.

    2003-01-01

    Nuclear design characteristics of duplex burnable poison rod were evaluated for three integral type burnable absorbers; Gadolinia, Erbia and IFBA. Inter-comparison was done for both 12 and 24 month cycle for Korean Standard Nuclear Plant. Fuel assemblies with duplex BP was designed to the equivalent assembly with 8 and 16 gadolinia BP 2 . Duplex BP is composed of inner region of natural U-Gd 2 O 3 , and outer shell of, UO 2 -Er2O 3 . In order to evaluate the duplex BP, assemblies with erbia and IFBA were compared with alternative options. A sensitivity studies were performed to the size of region, compositions and location of duplex BPs. It was shown that duplex BP gave favorable k-infinite curve to burnup, but IFBA provided the least residual reactivity penalty as EOC. Erbia was good for more negative MTCs. IFBA and erbia had better neutronic performance than gadolinia od duplex BP in the aspect of pin power peaking

  3. Investigation of neutron physical features of WWER-440 assembly containing differently enriched pins and Gd burnable poison

    International Nuclear Information System (INIS)

    Nemes, Imre

    2000-01-01

    In this paper different pin-distributions of WWER-440 fuel assembly are examined. Assemblies contain 3 Gd-doped pins (Hungarian design), 6 Gd-doped pins near the assembly corners (Russian design) and differently profiled U5-enrichment in different pins. The main neutron physical characteristics of this assemblies - as the function of burnup - are calculated using HELIOS code. The calculated parameters of different assembly designs are analyzed from the standpoint of fuel cycle economy and refueling design practice. (Authors)

  4. Burnable poison rod

    International Nuclear Information System (INIS)

    Natsume, Tomohiro.

    1988-01-01

    Purpose: To decrease the effect of water elimination and the effect of burn-up residue boron, thereby reduce the effect of burnable poison rods as the neutron poisons at the final stage of reactor core lifetime. Constitution: In a burnable poison rod according to the present invention, a hollow burnable poison material is filled in an external fuel can, an inner fuel can mounted with a carbon rod is inserted to the hollow portion of the burnable poison material and helium gases are charged in the outer fuel can. In such a burnable poison rod, the reactivity worths after the burning are reduced to one-half as compared with the conventional case. Accordingly, since the effect of the burnable poison as the neutron poisons is reduced at the final stage of the reactor core of lifetime, the excess reactivity of the reactor core is increased. (Horiuchi, T.)

  5. Characteristics and use of urania-gadolinia fuels

    International Nuclear Information System (INIS)

    1995-11-01

    Burnable absorber fuels (BAF) are utilized, or are being considered for utilization, in all BWRs, in most PWRs and more recently in WWERs. The topic is therefore relevant to approximately 330 out of the 420 operating reactors in the world, representing 280 of the 330 GW(e) installed capacity worldwide. In the light of this importance, the IAEA has decided to issue this report providing an overall view of the various aspects of BAF. With the exception of Chapter 1, the whole report is devoted to urania-gadolinia fuel (''Gd fuel''), the most commonly used BAF, and a comprehensive technical review of this topic is provided, although the report does not include a complete survey of all examples of Gd utilization throughout the industry. Refs, figs and tabs

  6. PWR burnable absorber evaluation

    International Nuclear Information System (INIS)

    Cacciapouti, R.J.; Weader, R.J.; Malone, J.P.

    1995-01-01

    The purpose of the study was to evaluate the relative neurotic efficiency and fuel cycle cost benefits of PWR burnable absorbers. Establishment of reference low-leakage equilibrium in-core fuel management plans for 12-, 18- and 24-month cycles. Review of the fuel management impact of the integral fuel burnable absorber (IFBA), erbium and gadolinium. Calculation of the U 3 O 8 , UF 6 , SWU, fuel fabrication, and burnable absorber requirements for the defined fuel management plans. Estimation of fuel cycle costs of each fuel management plan at spot market and long-term market fuel prices. Estimation of the comparative savings of the different burnable absorbers in dollar equivalent per kgU of fabricated fuel. (author)

  7. Burnable poison rod

    International Nuclear Information System (INIS)

    Natsume, Tomohiro.

    1988-01-01

    Purpose: To increase the reactor core lifetime by decreasing the effect of neutron absorption of burnable poison rods by using material with less neutron absorbing effect. Constitution: Stainless steels used so far as the coating material for burnable poison rods have relatively great absorption in the thermal neutral region and are not preferred in view of the neutron economy. Burnable poison rods having fuel can made of zirconium alloy shows absorption the thermal neutron region lower by one digit than that of stainless steels but they shows absorption in the resonance region and the cost is higher. In view of the above, the fuel can of the burnable poison material is made of aluminum or aluminu alloy. This can reduce the neutron absorbing effect by stainless steel fuel can and effectively utilize neutrons that have been wastefully absorbed and consumed in stainless steels. (Takahashi, M.)

  8. Analytical out-of-pile and in-pile experiments on gadolinia bearing fuels

    International Nuclear Information System (INIS)

    Bruet, M.; Francois, B.; Do, Q.; Bergeron, J.; Trotabas, M.

    1986-06-01

    New fuel management schemes in PWRs can be achieved through the use of burnable poisons like gadolinia bearing fuel rods. However, the introduction of such a design has required a qualification program, which has been performed in collaboration between CEA, FRAGEMA and/or FRAMATOME by specialized teams in CEA facilities. The main scoops of this program concern: the fabrication process; the out of pile physical properties determination: the in pile thermomechanical behaviour and fission product release; the neutronic studies in view to validate the Computed Gd efficiency and the LBP depletion calculation schemes and to analyse and assess various schemes of core calculations

  9. Burnable absorber coated nuclear fuel

    International Nuclear Information System (INIS)

    Chubb, W.; Radford, K.C.; Parks, B.H.

    1984-01-01

    A nuclear fuel body which is at least partially covered by a burnable neutron absorber layer is provided with a hydrophobic overcoat generally covering the burnable absorber layer and bonded directly to it. In a method for providing a UO 2 fuel pellet with a zirconium diboride burnable poison layer, the fuel body is provided with an intermediate niobium layer. (author)

  10. Heterogeneous burnable poisons:

    International Nuclear Information System (INIS)

    Leiva, Sergio; Agueda, Horacio; Russo, Diego

    1989-01-01

    The use of materials possessing high neutron absorption cross-section commonly known as 'burnable poisons' have its origin in BWR reactors with the purpose of improving the efficiency of the first fuel load. Later on, it was extended to PWR to compensate of initial reactivity without infringing the requirement of maintaining a negative moderator coefficient. The present tendency is to increase the use of solid burnable poisons to extend the fuel cycle life and discharge burnup. There are two concepts for the burnable poisons utilization: 1) heterogeneously distributions in the form of rods, plates, etc. and 2) homogeneous dispersions of burnable poisons in the fuel. The purpose of this work is to present the results of sinterability studies, performed on Al 2 O 3 -B 4 C and Al 2 O 3 -Gd 2 O 3 systems. Experiments were carried on pressing at room temperature mixtures of powders containing up to 5 wt % of B 4 C or Gd 2 O 3 in Al 2 O 3 and subsequently sintering at 1750 deg C in reducing atmosphere. Evaluation of density, porosity and microstructures were done and a comparison with previous experiences is shown. (Author) [es

  11. Computed phase equilibria for burnable neutron absorbing materials for advanced pressurized heavy water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Corcoran, E.C. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada)], E-mail: emily.corcoran@rmc.ca; Lewis, B.J.; Thompson, W.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, P.O. Box 17000, St. Forces, Kingston, Ont., K7K 7B4 (Canada); Hood, J. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada); Akbari, F.; He, Z. [Atomic Energy of Canada Ltd., Chalk River Laboratories, Chalk River, Ont., K0J 1J0 (Canada); Reid, P. [Atomic Energy of Canada Ltd., Sheridan Park, 2251 Speakman Drive, Mississauga, Ont., L5K 1B2 (Canada)

    2009-03-31

    Burnable neutron absorbing materials are expected to be an integral part of the new fuel design for the Advanced CANDU [CANDU is as a registered trademark of Atomic Energy of Canada Limited.] Reactor. The neutron absorbing material is composed of gadolinia and dysprosia dissolved in an inert cubic-fluorite yttria-stabilized zirconia matrix. A thermodynamic model based on Gibbs energy minimization has been created to provide estimated phase equilibria as a function of composition and temperature. This work includes some supporting experimental studies involving X-ray diffraction.

  12. Burnable neutron absorbers

    International Nuclear Information System (INIS)

    Radford, K.C.; Carlson, W.G.

    1985-01-01

    This patent deals with the fabrication of pellets for neutron absorber rods. Such a pellet includes a matrix of a refractory material which may be aluminum or zirconium oxide, and a burnable poison distributed throughout the matrix. The neutron absorber material may consist of one or more elements or compounds of the metals boron, gadolinium, samarium, cadmium, europium, hafnium, dysprosium and indium. The method of fabricating pellets of these materials outlined in this patent is designed to produce pores or voids in the pellets that can be used to take up the expansion of the burnable poison and to absorb the helium gas generated. In the practice of this invention a slurry of Al 2 O 3 is produced. A hard binder is added and the slurry and binder are spray dried. This powder is mixed with dry B 4 C powder, forming a homogeneous mixture. This mixture is pressed into green tubes which are then sintered. During sintering the binder volatilizes leaving a ceramic with nearly spherical high-density regions of

  13. Benchmark solution of contemporary PWR integral fuel burnable absorbers

    International Nuclear Information System (INIS)

    Stucker, D.L.; Hone, M.J.; Holland, R.A.

    1993-01-01

    This paper presents a closely controlled benchmark solution of the two major contemporary pressurized water reactor integral burnable absorber designs: zirconium diboride (ZrB 2 ) and gadolinia (Gd 2 O 3 ). The comparison is accomplished using self-generating equilibrium cycles with equal energy, equal discharge burnup, and equal safety constraints. The reference plant for this evaluation is a 3411-MW(thermal) Westinghouse four-loop nuclear steam supply system operating with an inlet temperature of 285.9 degrees C, a core coolant mass now rate of 16877.3 kg/s, and coolant pressure of 15.5 MPa. The reactor consists of 193 VANTAGE 5H fuel assemblies that are discharged at a region average burnup of 48.4 GWd/tonne U. Each fuel assembly contains a natural uranium axial blanket 15.24 cm long at the top and the bottom of the fuel rod. The burnable absorber rods are symmetrically radially dispersed within the fuel assembly such that intrabundle power peaking is minimized. The burnable absorber material for both ZrB 2 and Gd 2 O 3 is axially zoned to the central 304.8 cm of the absorber-bearing fuel rods. The fuel management was constrained such that the thermal and safety limitations of F δH q -5 /degrees C were simultaneously achieved. The maximum long-term operating soluble boron concentration was also limited to 446 effective full-power days (EFPDs) including 14 EFPDs of power coastdown were assumed

  14. Burnable neutron absorbers

    International Nuclear Information System (INIS)

    Radford, K.C.; Carlson, W.G.

    1985-01-01

    This invention provides ceramic processing including sintering schedules which produce annular pellets containing burnable poisons for use in reactor control rods. Typically the powder includes Al 2 O 3 and from 1 to 50 weight percent B 4 C. The Al 2 O 3 and B 4 C, appropriately sized, are milled in a ball mill with liquid to produce a slurry. The slurry is spray dried to produce small spheres of the mixed powder, which is mixed with adequate organic binder and plasticizer and formed into a hollow green body having the shape of a tube. The green body is sintered to produce a ceramic tube from which the pellets are cut. The tube is sintered to size so that the pellets have the required dimensions. It is an important feature of this invention that the powder is formed into the green body by applying isostatic pressure to the powder

  15. Burnable neutron absorbers

    International Nuclear Information System (INIS)

    Radford, K.C.; Carlson, W.G.

    1983-01-01

    A neutron-absorber body for use in burnable poison rods in a nuclear reactor. The body is composed of a matrix of Al 2 O 3 containing B 4 C, the neutron absorber. Areas of high density polycrystalline Al 2 O 3 particles are predominantly encircled by pores in some of which there are B 4 C particles. This body is produced by initially spray drying a slurry of A1 2 O 3 powder to which a binder has been added. The powder of agglomerated spheres of the A1 2 O 3 with the binder are dry mixed with B 4 C powder. The mixed powder is formed into a green body by isostatic pressure and the green body is sintered. The sintered body is processed to form the neutron-absorber body. In this case the B 4 C particles are separate from the spheres resulting from the spray drying instead of being embedded in the sphere

  16. Usage of burnable poison on research reactors

    International Nuclear Information System (INIS)

    Villarino, Eduardo Anibal

    2002-01-01

    The fuel assemblies with burnable poison are widely used on power reactors, but there are not commonly used on research reactors. This paper shows a neutronic analysis of the advantages and disadvantages of the burnable poison usage on research reactors. This paper analyses both burnable poison design used on research reactors: Boron on the lateral wall and Cadmium wires. Both designs include a parametric study on the design parameters like the amount and geometry of the burnable poison. This paper presents the design flexibility using burnable poisons, it does not find an optimal or final design, which it will strongly depend on the core characteristics and fuel management strategy. (author)

  17. Absorber management using burnable poisons

    International Nuclear Information System (INIS)

    Mortensen, L.

    1977-06-01

    An investigation of the problem of optimal control carried out by means of a two-dimensional model of a PWR reactor. A solution is found to the problem, and the possibility of achieving optimal control with burnable poisons such as boron, cadmium and gadolinium is discussed. Further, an attempt is made to solve the control problem of BWR, but no final solution is found. (author)

  18. Burnable poison fuel element and its fabrication

    International Nuclear Information System (INIS)

    Zukeran, Atsushi; Inoue, Kotaro; Aizawa, Hiroko.

    1985-01-01

    Purpose: To enable to optionally vary the excess reactivity and fuel reactivity. Method: Burnable poisons with a large neutron absorption cross section are contained in fuel material, by which the excess reactivity at the initial stage in the reactor is suppressed by the burnable poisons and the excess reactivity is released due to the reduction in the atomic number density of the burnable poisons accompanying the burning. The burnable poison comprises spherical or rod-like body made of a single material or spherical or rod-like member made of a plurality kind of materials laminated in a layer. These spheres or rods are dispersed in the fuel material. By adequately selecting the shape, combination and the arrangement of the burnable poisons, the axial power distribution of the fuel rods are flattened. (Moriyama, K.)

  19. Neutron evaluation of burnable poison insertion in pressurized water reactor

    International Nuclear Information System (INIS)

    Faria, Rochkhudson Batista de

    2013-01-01

    The development of this work was to match the 'Burn-up Credit Criticality Benchmark - Phase II-D - PWR-UO 2 Assembly Study of Control Rod Effects on Spent Fuel Composition' (case 15), which was modeled using the code MCNP5 and SCALE 6.0. The results of the infinite multiplication factor (k inf ) were compared with those obtained by international institutions. Later we performed in this same benchmark, a sensitivity analysis using SCALE 6.0. Thus, we tested several changes in case 15 of Benchmark, such as insertion of different percentages of burnable poison, changing the number and positions of the rods. In all cases were analyzed, comparisons and discussions about the results. The same methodology was applied to the reactor core of the Nuclear Plant in Brazil, Angra II, initially to evaluate its behavior when subjected to a variation in the percentage of burnable poison and then, introduce changes also in the enrichment of nuclear fuel, doing the appropriate comparisons of results. Considering results and experience gained, the Department of Nuclear Engineering, is prepared to control analysis of reactivity with the use of different types of burnable poisons under the code SCALE 6.0 through its various modules. (author)

  20. Correlation of waterside corrosion and cladding microstructure in high-burnup fuel and gadolinia rods

    International Nuclear Information System (INIS)

    Chung, H.M.

    1989-09-01

    Waterside corrosion of the Zircaloy cladding has been examined in high-burnup fuel rods from several BWRs and PWRs, as well as in 3 wt % gadolinia burnable poison rods obtained from a BWR. The corrosion behavior of the high-burnup rods was then correlated with results from a microstructural characterization of the cladding by optical, scanning-electron, and transmission-electron microscopy (OM, SEM, and TEM). OM and SEM examination of the BWR fuel cladding showed both uniform and nodular oxide layers 2 to 45 μm in thickness after burnups of 11 to 30 MWd/kgU. For one of the BWRs, which was operated at 307 degree C rather than the normal 288 degree C, a relatively thick (50 to 70 μm) uniform oxide, rather than nodular oxides, was observed after a burnup of 27 to 30 MWd/kgU. TEM characterization revealed a number of microstructural features that occurred in association with the intermetallic precipitates in the cladding metal, apparently as a result of irradiation-induced or -enhanced processes. The BWR rods that exhibited white nodular oxides contained large precipitates (300 to 700 nm in size) that were partially amorphized during service, indicating that a distribution of the large intermetallic precipitates is conductive to nodular oxidation. 23 refs., 9 figs

  1. Development of Improved Burnable Poisons for Commercial Nuclear Power Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Renier, J.A.

    2002-04-17

    Burnable poisons are used in all modern nuclear reactors to permit higher loading of fuel without the necessity of an overly large control rod system. This not only permits a longer core life but can also be used to level the power distribution. Commercial nuclear reactors commonly use B{sub 4}C in separate non-fueled rods and more recently, zirconium boride coatings on the fuel pellets or gadolinium oxide mixed with the fuel. Although the advantages are great, there are problems with using these materials. Boron, which is an effective neutron absorber, transmutes to lithium and helium upon absorption of a neutron. Helium is insoluble and is eventually released to the interior of the fuel rod, where it produces an internal pressure. When sufficiently high, this pressure stress could cause separation of the cladding from the fuel, causing overly high centerline temperatures. Gadolinium has several very strongly absorbing isotopes, but not all have large cross sections and result in residual burnable poison reactivity worth at the end of the fuel life. Even if the amount of this residual absorber is small and the penalty in operation small, the cost of this penalty, even if only several days, can be very high. The objective of this investigation was to study the performance of single isotopes in order to reduce the residual negative reactivity left over at the end of the fuel cycle. Since the behavior of burnable poisons can be strongly influenced by their configuration, four forms for the absorbers were studied: homogeneously mixed with the fuel, mixed with only the outer one-third of the fuel pellet, coated on the perimeter of the fuel pellets, and alloyed with the cladding. In addition, the numbers of fuel rods containing burnable poison were chosen as 8, 16, 64, and 104. Other configurations were chosen for a few special cases. An enrichment of 4.5 wt% {sup 235}U was chosen for most cases for study in order to achieve a 4-year fuel cycle. A standard pressurized

  2. Cutting system for burnable poison rod

    International Nuclear Information System (INIS)

    Shiina, Atsushi; Toyama, Norihide; Koshino, Yasuo; Fujii, Toshio

    1989-01-01

    Burnable poison rods attached to spent fuels are contained in a containing box and transported to a receiving pool. The burnable poison rod-containing box is provisionally situated by the operation to a handling device to a provisional setting rack in a cutting pool and attached to a cutting guide of a cutting device upon cutting. The burnable poison rod is cut only in a cutting pool water and tritium generated upon cutting is dissolved into the cutting pool water. Diffusion of tritium is thus restricted. Further, the cutting pool is isolated by a partition device from the receiving pool during cutting of the burnable poison rod. Accordingly, water in which tritium is dissolved is inhibited from moving to the receiving pool and prevail of tritium contamination can be avoided. (T.M.)

  3. Low reactivity penalty burnable poison rods

    International Nuclear Information System (INIS)

    1978-01-01

    A nuclear reactor burnable poison rod is described which consists of an elongated tubular sheath enclosing a neutron absorbing material which, at least during reactor operation, also encloses a neutron moderating material. The excess reactivity existing at the beginning of core life is compensated for by the depletion of the burnable poison throughout the life of the core, so that the life of the core is extended. (UK)

  4. Fuel assembly and burnable poison rod

    International Nuclear Information System (INIS)

    Hirukawa, Koji.

    1993-01-01

    In a fuel assembly having burnable poison rods arranged therein, the burnable poison comprises an elongate small outer tube and an inner tube coaxially disposed within the outer tube. Upper and lower end tubes each sealed at one end are connected to both of the upper and lower ends in the inner and the outer tubes respectively. A coolant inlet hole is disposed to the lower end tube, while a coolant leakage hole is disposed to the upper end tube. Burnable poison members are filled in an annular space. Further, the burnable poison-filling region is disposed excepting portions for 1/20 - 1/12 of the effective fuel length at each of the upper and the lower ends of the fuel rod. Then, the concentration of the burnable poisons in a region above a boundary defined at a position 1/3 - 1/2, from beneath, of the effective fuel length is made smaller than that in the lower region. This enables to suppress excess reactions of fuels to reduce the mass of the burnable neutron. Excellent reactivity control performance at the initial stage of the burning can be attained. (T.M.)

  5. Evaluation of the presence of a burnable absorber in an assembly 3x3 type PWR

    International Nuclear Information System (INIS)

    Martinez F, M. A.; Del Valle G, E.; Alonso V, G.

    2008-01-01

    In the present work the effect is evaluated that causes the presence of a burnable absorber in an adjustment of rods of 3x3 of a fuel assembly type PWR using CASMO-4 code, when comparing the infinite multiplication factor and some average cross sections by means of codes MCNP-4A, CASMO-3 and HELIOS. For this evaluation two cases are evaluated: first consists of an adjustment of rods of 3x3 full completely of fuel and the second consists of a central rod full with a burnable absorber type wet annular burnable absorber (WABA) and the remaining full fuel rods. In both cases the enrichment of the fissile isotopes is varied, for two types of fuel, MOX degree armament and UO 2 . (Author)

  6. Irradiation test of borosilicate glass burnable poison

    International Nuclear Information System (INIS)

    Feng Mingquan; Liao Zumin; Yang Mingjin; Lu Changlong; Huang Deyang; Zeng Wangchun; Zhao Xihou

    1991-08-01

    The irradiation test and post-irradiation examinations for borosilicate glass burnable poison are introduced. Examinations include visual examination, measurement of dimensions and density, and determination of He gas releasing and 10 B burnup. The corrosion and phenomenon of irradiation densification are also discussed. Two type glass samples have been irradiated with different levels of neutron flux. It proved that the GG-17 borosilicate glass can be used as burnable poison to replace the 10 B stainless steel in the Qinshan Nuclear Power Plant, and it is safe, economical and reasonable

  7. Burnable poison management in a HTR

    Energy Technology Data Exchange (ETDEWEB)

    Pedersen, J

    1971-09-21

    It is the purpose with this paper to describe the state-of-the-art of burnable poison investigations made within the Dragon Project and to give the results of a number of calculations, which show that it is possible to control the large initial surplus reactivity of the first core and the radial power distribution with two types of burnable poison sticks with Gadolinium (one type of stick to be used in the inner core region, the other in the outer core region), where the poison will burn away so that keff always stays around the desired value 1.03, and with the radial form-factor not exceeding 1.20. The calculations made for this paper are not too accurate, especially the chosen timestep for calculating the burn-up of the burnable poison stick proved to be too large. Nevertheless, the calculations are good enough to draw the above mentioned conclusions, although they have not given the concentration of Gadolinium to be used in the burnable poison sticks very accurately.

  8. Spider and burnable poison rod combinations

    International Nuclear Information System (INIS)

    Edwards, G.T.; Schluderberg, D.C.

    1980-01-01

    An improved design of burnable poison rods and associated spiders used in fuel assemblies of pressurized water power reactor cores, is described. The rods are joined to the spider arms in a manner which is proof against the reactor core environment and yet allows the removal of the rods from the spider simply, swiftly and delicately. (U.K.)

  9. Spider and burnable poison rod combinations

    International Nuclear Information System (INIS)

    Walton, L.A.

    1980-01-01

    A description is given of an improved design of burnable poison rods and their associated spiders used in the fuel assemblies of pressurized water power reactor cores which allows the rods to be installed and removed more quickly, simply and gently than in previously described systems. (U.K.)

  10. Advanced gadolinia core and Toshiba advanced reactor management system

    International Nuclear Information System (INIS)

    Miyamoto, Toshiki; Yoshioka, Ritsuo; Ebisuya, Mitsuo

    1988-01-01

    At the Hamaoka Nuclear Power Station, Unit No. 3, advanced core design and core management technology have been adopted, significantly improving plant availability, operability and reliability. The outstanding technologies are the advanced gadolinia core (AGC) which utilizes gadolinium for the axial power distribution control, and Toshiba advanced reactor management system (TARMS) which uses a three-dimensional core physics simulator to calculate the power distribution. Presented here are the effects of these advanced technologies as observed during field testing. (author)

  11. Implementation of a Gadolinium Burnable Absorber in the Carbide LEU-NTR

    International Nuclear Information System (INIS)

    Venneria, Paolo; Kim, Yonghee

    2015-01-01

    Among the most crucial are the rapid reactivity depletion during full-power operation and the positive reactivity insertion during the full-submersion criticality accident. In previous work, it has been suggested that both challenges can be mitigated through the successful implementation of a burnable absorber in the active core. Of the poisons previously surveyed, one of the most promising is Gadolinium in the form of Gadolina (Gd2O4). This paper explores the possibility of different methods by which the Gadolinia can be implemented in the core and makes a preliminary study of its effect on the full submersion criticality accident and the reactivity depletion during operation. The application of a Gadolinium neutron absorber in the active core region of the LEU-NTR has been shown to be neutronically feasible. It can be introduced into the core in various locations without resulting in core performance loss. The utility of the poison in terms of mitigating the full-submersion reactivity accident and the rapid change in reactivity during full-power operation have been preliminarily shown and the first steps towards eventual implementation made. Future work will consist of determining the maximum poison content in the core and tailoring the self-shielding effect in order to determine a specific Gd depletion rate

  12. Application of gadolinia credit to cask transportation of BWR-STEP3 SFAs

    International Nuclear Information System (INIS)

    Kikuchi, Tsukasa; Mitsuhashi, Ishi; Ito, Dai-ichiro; Nakamura, Yu

    2003-01-01

    Instead of the fresh-fuel assumption, the application of gadolinia credit to cask transportation of BWR SFAs is studied. Its efficacy for BWR-STEP2 SFAs had already been estimated. This paper reports on the application of gadolinia credit to cask transportation of BWR-STEP3 SFAs. (author)

  13. Summary of SEMO experience with PWR's cores containing Gadolinia bearing fuel in Tihange 1 nuclear power station

    International Nuclear Information System (INIS)

    Melice, M.; Jadot, J.J.; Duflou, P.; Wergifosse, C. de

    1984-01-01

    Future operating plans for Tihange unit 1 are based on cycle lengths approaching 18 months (from cycle 12). Since cycle 7, Gadolinia bearing assemblies were included in the reload batches in order to evaluate neutronic design methods employed. This Gadolinia program is briefly set out. Comparisons of measured to calculated data following the performance of the Gadolinia assemblies through cycles 7 and 8 are discussed. Loading pattern of cycle 9 including 4 Gadolinia high concentration assemblies and special features of cycle 10 are presented. An original device for ''in situ'' Gadolinia rod insertion into fresh assemblies is shortly described. (author)

  14. Initial study on burnable poisons in the Dragon HTR design

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, U; Pedersen, J

    1971-06-15

    A first study on the effects of burnable poisons in a High Temperature Reactor is given in this paper, and some of the problems concerning the layout and distribution of burnable poison sticks in the core are explained. Time has not allowed us to obtain satisfactory solutions to these problems, but we hope, that this study could form the basis of valuable discussions on ways and means to overcome the difficulties of burnable poison management in HTRs.

  15. Research on application of burnable poison in pebble bed HTR

    International Nuclear Information System (INIS)

    Wei Chunlin; Zhang Jian; Shan Wenzhi; Jing Xingqing

    2013-01-01

    Burnable poison in fuel ball was used in pebble bed high-temperature gas-cooled reactor (HTR) to optimize the shape and the peak factor of power distribution in certain conditions. Two options are available and evaluated, that is the homogeneous burnable poison in graphite matrix and burnable poison particles (BPPs) in fuel balls. Due to the absorption cross section of "1"0B, the depletion speed for homogeneous burnable poison is very fast, and difficult to control, on the other side, the depletion speed of BPPs can be optimized respecting to its size, and better shape and peak value of power distribution can be achieved. (authors)

  16. Review of the status of reactor physics predictive methods for burnable poisons in CAGRs

    International Nuclear Information System (INIS)

    Edens, D.J.; McEllin, M.

    1983-01-01

    An essential component of the design of Commercial Advanced Gas Cooled Reactor fuel necessary to achieve higher discharge irradiations is the incorporation of burnable poisons. The poisons enable the more highly enriched fuel required to reach higher irradiation to be loaded without increasing the peak channel power. The optimum choice of fuel enrichment and poison loading will be made using reactor physics predictive methods developed by Berkeley Nuclear Laboratories. These methods and the evidence available to support them from theoretical comparisons, zero energy experiments, WAGR irradiations, and measurements on operating CAGRs are described. (author)

  17. Review of the status of reactor physics predictive methods for burnable poisons in CAGRs

    International Nuclear Information System (INIS)

    Edens, D.J.; McEllin, M.

    1983-01-01

    An essential component of the design of Commercial Advanced Gas Cooled Reactor fuel necessary to achieve higher discharge irradiations is the incorporation of burnable poisons. The poisons enable the more highly enriched fuel required to reach higher irradiation to be loaded without increasing the peak channel power. The optimum choice of fuel enrichment and poison loading will be made using reactor physics predictive methods developed by Berkeley Nuclear Laboratories. The paper describes these methods and the evidence available to support them from theoretical comparisons, zero energy experiments, WAGR irradiations, and measurements on operating CAGR's. (author)

  18. Hot channel calculation methodologies in case of Gd burnable poison

    International Nuclear Information System (INIS)

    Panka, I.; Kereszturi, A.

    2008-01-01

    The final step in the safety analysis is the investigation of the fulfilment of the acceptance criteria using hot channel calculations. Recently, there has been under way at Paks NPP to introduce a new, higher enriched (4.2 %) fuel type containing Gd burnable poison. To do that, for some transients the DBA analyses must be repeated and last year, as one of the first steps in this process, it was needed to review the hot channel calculation methodologies used in the analyses. The goal of the paper is to summarize some aspects of the hot channel calculation methodologies using different lattice pitches and different fuel types (Gd or non Gd and different enrichments). Mainly, three topics are discussed. First, the influence of the radial power distribution (and other burnup dependent parameters) inside the fuel pin are investigated, and then we discuss the problem of the selection of the appropriate 'frame parameter' in connection with the initial power level at the initial stationary state of DBA transients. Finally, we are trying to answer the question: is it possible to build up a conservative single closed sub-channel approach against multi channel approach?(Authors)

  19. Burnable poison option for DUPIC fuel

    International Nuclear Information System (INIS)

    Choi, Hang Bok; Cupta, H. P.

    1996-08-01

    The mechanisms of positive coolant void reactivity of CANDU natural uranium and DUPIC fuel have been studied. The design study of DUPIC fuel was performed using the burnable poison material in the center pin to reduce the coolant void reactivity. The amount of burnable poison was determined such that the prompt inverse period of DUPIC fuel upon full coolant voiding is the same as that of natural uranium fuel at equilibrium burnup. A parametric study on various burnable poisons has shown that natural dysprosium has more merit over other materials because it uniformly controls the void reactivity throughout the burnup with reasonable amount of poison. Additional studies on the option of using scattering or absorber material in the center pin position and the option using variable fuel density were performed. In any case of option using variable fuel density were performed. In any case of options to reduce the void reactivity, it was found that either the discharge burnup and/or the relative linear pin power are sacrificed. A preliminary study was performed for the evaluation of reference DUPIC fuel performance especially represented by Stress Corrosion Cracking(SCC) parameters which is mainly influenced by the refueling operations. For the reference 2-bundle shift refueling scheme, the predicted ramped power and power increment of the reference DUPIC fuel are below the SCC thresholds of CANDU natural uranium fuel. For a 4-bundle shift refueling scheme, the envelopes of element ramped power and power increment upon refueling are 8% and 44% higher than those of a 2-bundle shift refueling scheme on the average, respectively, but still have margins to the failure thresholds of natural uranium fuel. 23 tabs., 25 figs., 20 refs. (Author)

  20. Burnable absorber for the PIK reactor

    International Nuclear Information System (INIS)

    Gostev, V.V.; Smolskii, S.L.; Tchmshkyan, D.V.; Zakharov, A.S.; Zvezdkin, V.S.; Konoplev, K.A.

    1998-01-01

    In the reactor PIK design a burnable absorber is not used and the cycle duration is limited by the rods weight. Designed cycle time is two weeks and seams to be not enough for the 100 MW power research reactor equipped by many neutron beams and experimental facilities. Relatively frequent reloading reduces the reactor time on full power and in this way increases the maintenance expenses. In the reactor core fuel elements well mastered by practice are used and its modification was not approved. We try to find the possibilities of installation in the core separate burnable elements to avoid poison of the fuel. It is possible to replace a part of the fuel elements by absorbers, since the fuel elements are relatively small (diameter 5.15mm, uranium 235 content 7.14g) and there are more then 3800 elements in the core. Nevertheless, replacing decreases the fuel burnup and its consumption. In the PIK fuel assembles a little part of the volume is occupied by the dumb elements to create a complete package of the assembles shroud, that is necessary in the hydraulic reasons. In the presented report the assessment of such a replacement is done. As a burnable material Gadolinium was selected. The measurements or the beginning of cycle were performed on the critical facility PIK. The burning calculation was confirmed by measurements on the 18MW reactor WWR-M. The results give the opportunity to twice the cycle duration. The proposed modification of the fuel assembles does not lead to alteration in the other reactor systems, but it touch the burned fuel reprocessing technology. (author)

  1. A consolidation process for spent burnable poison rod assemblies

    International Nuclear Information System (INIS)

    Yamamoto, Y.; Harada, M.; Komatsu, Y.

    1985-01-01

    A new consolidation system for the spent burnable poison assembly utilizing a sequence control robot operated under water was proposed. A credible accident in the system was analyzed mainly from the viewpoint of tritium release, based on the diffusion analysis of tritium in borosilicate glass. It was found that the amount of tritium released would be small even after the rupture of burnable poison rods. An experiment on a new consolidation system was performed using spent burnable poison assemblies. The volume of burnable poison assemblies was reduced safely and securely by a factor of 7 to 14 for burnable poison rods and by 22 for hold-down portions. It was proved that the consolidation system is collectively feasible

  2. Burnable absorber-integrated Guide Thimble (BigT) - 1. Design concepts and neutronic characterization on the fuel assembly benchmarks

    International Nuclear Information System (INIS)

    Yahya, Mohd-Syukri; Yu, Hwanyeal; Kim, Yonghee

    2016-01-01

    This paper presents the conceptual designs of a new burnable absorber (BA) for the pressurized water reactor (PWR), which is named 'Burnable absorber-integrated Guide Thimble' (BigT). The BigT integrates BA materials into standard guide thimble in a PWR fuel assembly. Neutronic sensitivities and practical design considerations of the BigT concept are points of highlight in the first half of the paper. Specifically, the BigT concepts are characterized in view of its BA material and spatial self-shielding variations. In addition, the BigT replaceability requirement, bottom-end design specifications and thermal-hydraulic considerations are also deliberated. Meanwhile, much of the second half of the paper is devoted to demonstrate practical viability of the BigT absorbers via comparative evaluations against the conventional BA technologies in representative 17x17 and 16x16 fuel assembly lattices. For the 17x17 lattice evaluations, all three BigT variants are benchmarked against Westinghouse's existing BA technologies, while in the 16x16 assembly analyses, the BigT designs are compared against traditional integral gadolinia-urania rod design. All analyses clearly show that the BigT absorbers perform as well as the commercial BA technologies in terms of reactivity and power peaking management. In addition, it has been shown that sufficiently high control rod worth can be obtained with the BigT absorbers in place. All neutronic simulations were completed using the Monte Carlo Serpent code with ENDF/B-VII.0 library. (author)

  3. Special quasirandom structures for gadolinia-doped ceria and related materials

    KAUST Repository

    Wang, Hao; Chroneos, Alexander I.; Jiang, Chao; Schwingenschlö gl, Udo

    2012-01-01

    cells describing 9% and 12% gadolinia doped ceria. These SQS cells are transferable and can be used to model related materials such as yttria stabilized zirconia. To demonstrate the applicability of the method we use density functional theory

  4. Applying burnable poison particles to reduce the reactivity swing in high temperature reactors with batch-wise fuel loading

    International Nuclear Information System (INIS)

    Kloosterman, J.L.; Dam, H. van; Hagen, T.H.J.J. van der

    2003-01-01

    Burnup calculations have been performed on a standard HTR fuel pebble with a radius of 3 cm containing 9 g of 8% enriched uranium and burnable poison particles (BPP) made of B 4 C highly enriched in 10 B. The radius of the BPP and the number of particles per fuel pebble have been varied to find the flattest reactivity-to-time curve. It was found that for a k∞ of 1.1, a reactivity swing as low as 2% can be obtained when each fuel pebble contains about 1070 BPP with a radius of 75 μm. For coated BPP that consist of a graphite kernel with a radius of 300 μm covered with a B 4 C burnable poison layer, a similar value for the reactivity swing can be obtained. Cylindrical particles seem to perform worse. In general, the modification of the geometry of BPP is an effective means to tailor the reactivity curve of HTRs

  5. Characterization of gadolinia doped ceria prepared with nanostructured powders

    International Nuclear Information System (INIS)

    Batista, R.M.; Muccillo, E.N.S.

    2012-01-01

    Gadolinia doped ceria is a potential material for application as solid electrolyte in solid oxide fuel cells that operate at intermediate temperatures. The performance of this kind of device is strongly influenced by the properties of the solid electrolyte, and then, by its microstructure. In this work the microstructure evolution of materials with surface area between 7 and 200 m 2 /g was investigated in detail. Cylindrical pellets were prepared by isostatic compaction and sintered in the 700 deg C to 1400 deg C temperature range. X-ray diffraction experiments were conducted to follow the crystallite growth. The microstructure evolution was accompanied by scanning electron microscopy. The densification was estimated by the geometric parameters of the samples and by dilatometry. The results revealed a fast sintering kinetics for materials with finer particle size, as expected. Different behaviors for crystallite growth were verified. (author)

  6. Calculation of burnable cells-Hammer versus Leopard

    International Nuclear Information System (INIS)

    Dias, A.M.; Almeida, C.U.C. de; Pina, C.M. de; Prestes, L.F.; Lederman, L.; Nunes, N.P.; Branco, W.H.

    1977-02-01

    The nuclear parameters for the Angra-1 reactor core are obtained from the cross sections of soluble boron and burnable boron, calculated by the code CITHAM. The results are compared with those developed by the code LEOCIT [pt

  7. Study of low leakage reload schedulle without burnable posion for Angra-1

    International Nuclear Information System (INIS)

    Sakai, M.; Dias, A.

    1989-01-01

    At the moment, there is a world trend to design larger cycles for PWR. Then the reload batches are increased, the enrichment in 235 U is increased and/or advanced fuel management strategies with radial low neutron leakage are applied. For the low leakage reloads of Angra-1 calculations were performed for different number of fuel assemblies for reaload batch, 32,36,40,44 and 48, from the 4th cycle up to equilibrium cycle for two different enrichments 3,4 W/O and 3,9 W/O in 235 U. The results showed that for the enrichments used without burnable posion it is possible to reach an increase in cycle lenghts between 3% and 8% for the same conditions. (author) [pt

  8. Nodal Diffusion Burnable Poison Treatment for Prismatic Reactor Cores

    International Nuclear Information System (INIS)

    Ougouag, A.M.; Ferrer, R.M.

    2010-01-01

    The prismatic block version of the High Temperature Reactor (HTR) considered as a candidate Very High Temperature Reactor (VHTR)design may use burnable poison pins in locations at some corners of the fuel blocks (i.e., assembly equivalent structures). The presence of any highly absorbing materials, such as these burnable poisons, within fuel blocks for hexagonal geometry, graphite-moderated High Temperature Reactors (HTRs) causes a local inter-block flux depression that most nodal diffusion-based method have failed to properly model or otherwise represent. The location of these burnable poisons near vertices results in an asymmetry in the morphology of the assemblies (or blocks). Hence the resulting inadequacy of traditional homogenization methods, as these 'spread' the actually local effect of the burnable poisons throughout the assembly. Furthermore, the actual effect of the burnable poison is primarily local with influence in its immediate vicinity, which happens to include a small region within the same assembly as well as similar regions in the adjacent assemblies. Traditional homogenization methods miss this artifact entirely. This paper presents a novel method for treating the local effect of the burnable poison explicitly in the context of a modern nodal method.

  9. Depletion optimization of lumped burnable poisons in pressurized water reactors

    International Nuclear Information System (INIS)

    Kodah, Z.H.

    1982-01-01

    Techniques were developed to construct a set of basic poison depletion curves which deplete in a monotonical manner. These curves were combined to match a required optimized depletion profile by utilizing either linear or non-linear programming methods. Three computer codes, LEOPARD, XSDRN, and EXTERMINATOR-2 were used in the analyses. A depletion routine was developed and incorporated into the XSDRN code to allow the depletion of fuel, fission products, and burnable poisons. The Three Mile Island Unit-1 reactor core was used in this work as a typical PWR core. Two fundamental burnable poison rod designs were studied. They are a solid cylindrical poison rod and an annular cylindrical poison rod with water filling the central region.These two designs have either a uniform mixture of burnable poisons or lumped spheroids of burnable poisons in the poison region. Boron and gadolinium are the two burnable poisons which were investigated in this project. Thermal self-shielding factor calculations for solid and annular poison rods were conducted. Also expressions for overall thermal self-shielding factors for one or more than one size group of poison spheroids inside solid and annular poison rods were derived and studied. Poison spheroids deplete at a slower rate than the poison mixture because each spheroid exhibits some self-shielding effects of its own. The larger the spheroid, the higher the self-shielding effects due to the increase in poison concentration

  10. Development of Improved Burnable Poisons for Commercial Nuclear Power Reactors

    International Nuclear Information System (INIS)

    Grossbeck, M. L.; Renier, J-P.A.; Bigelow, Tim

    2003-01-01

    Burnable poisons are used in nuclear reactors to produce a more level distribution of power in the reactor core and to reduce to necessity for a large control system. An ideal burnable poison would burn at the same rate as the fuel. In this study, separation of neutron-absorbing isotopes was investigated in order to eliminate isotopes that remain as absorbers at the end of fuel life, thus reducing useful fuel life. The isotopes Gd-157, Dy-164, and Er-167 were found to have desirable properties. These isotopes were separated from naturally occurring elements by means of plasma separation to evaluate feasibility and cost. It was found that pure Gd-157 could save approximately $6 million at the end of four years. However, the cost of separation, using the existing facility, made separation cost- ineffective. Using a magnet with three times the field strength is expected to reduce the cost by a factor of ten, making isotopically separated burnable poisons a favorable method of increasing fuel life in commercial reactors, in particular Generation-IV reactors. The project also investigated various burnable poison configurations, and studied incorporation of metallic burnable poisons into fuel cladding

  11. New burnable absorber for long-cycle low boron operation of PWRs

    International Nuclear Information System (INIS)

    Choe, Jiwon; Shin, Ho Cheol; Lee, Deokjung

    2016-01-01

    Highlights: • A burnable absorber design for advanced PWRs with a low soluble boron concentration. • The burnable absorber consists of a UO 2 – 157 Gd 2 O 3 rod with a thin layer of Zr 167 Er 2 . • Three verification cases: two kinds of fuel assemblies and an OPR-1000 core. - Abstract: This paper presents a new high performance burnable absorber (BA) design for advanced Pressurized Water Reactors (PWRs) aiming for a long-cycle operation with a low soluble boron concentration. The new BA consists of a UO 2 – 157 Gd 2 O 3 rod covered with a thin layer of Zr 167 Er 2 . A key feature of this new BA is that enriched isotopes, 157 Gd and 167 Er, are used as absorber materials. Since the high absorption cross section of 157 Gd can reduce the mass fraction of Gd 2 O 3 in UO 2 –Gd 2 O 3 , the thermal margin of fuel rods will increase with higher heat conductivity. Also, the 157 Gd transmutes into 158 Gd by neutron absorption and therefore the residual penalty at the end of cycle (EOC) will decrease. Since 167 Er has a resonance near the thermal neutron energy region, the moderator temperature coefficient (MTC) will become more negative and the control rod worth will increase. These advantages of the new BA are demonstrated with three verification cases: a 17 × 17 Westinghouse (WH) type fuel assembly, a 16 × 16 Combustion Engineering (CE) type fuel assembly, and an OPR-1000 equilibrium core.

  12. Production method of burnable poison incorporated fuel pellet by coating

    International Nuclear Information System (INIS)

    Naito, Naoyoshi.

    1993-01-01

    A cylindrical member is formed with an organic material which is melted, decomposed or evaporated by heating. Such organic materials include polyethylene and polyvinyl alcohol, for example. A predetermined amount of burnable poisons are homogeneously incorporated in the cylindrical member by a means, such as melting before fabricating it into a cylindrical shape. UO 2 fuel pellets are inserted to the cylindrical member and heated, to scatter only the organic materials, so that non-volatile burnable poisons are homogeneously left on the surface of the pellets. It is preferred that the cylindrical member having pellets inserted therein is inserted to a cladding tube and applied with a heat treatment. With such procedures, a UO 2 pellet is coated with burnable poisons by a convenient and compact device. In addition, grinding step after the coating is unnecessary. (I.N.)

  13. Optimal burnable poison utilization in PWR core reload design

    International Nuclear Information System (INIS)

    Downar, T.J.

    1986-01-01

    A method was developed for determining the optimal distribution and depletion of burnable poisons in a Pressurized Water Reactor core. The well-known Haling depletion technique is used to achieve the end-of-cycle core state where the fuel assembly arrangement is configured in the absence of all control poison. The soluble and burnable poison required to control the core reactivity and power distribution are solved for as unknown variables while step depleting the cycle in reverse with a target power distribution. The method was implemented in the NRC approved licensing code SIMULATE

  14. Magnetron sputtered gadolinia-doped ceria diffusion barriers for metal-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Sønderby, Steffen; Klemensø, Trine; Christensen, Bjarke H.

    2014-01-01

    Gadolinia-doped ceria (GDC) thin films are deposited by reactive magnetron sputtering in an industrial-scale setup and implemented as barrier layers between the cathode and electrolyte in metal-based solid oxide fuel cells consisting of a metal support, an electrolyte of ZrO2 co-doped with Sc2O3...

  15. Analysis of a possible experimental assessment of a prototype fuel element containing burnable poison in the RA-3 reactor

    International Nuclear Information System (INIS)

    Lerner, Ana Maria; Madariaga, Marcelo

    2002-01-01

    The Argentine RA-3 research reactor (5 MW) is presently operated with LEU fuel by the National Atomic Energy Commission (CNEA). It belongs to the group of nuclear installations controlled, from the radiological and nuclear safety point of view, by the Nuclear Regulatory Authority (ARN). A new type of fuel elements containing burnable absorbers, with similar enrichment as the standard fuel elements but greater fissile contents, has recently been proposed for a new Argentine reactor design (RRR). In this framework the ARN considers interesting, if technically possible, the performance of an experiment in the RA-3 reactor. The experiment might enable, for such fuel element containing burnable poison, the verification of its neutronic behaviour under irradiation as well as a validation of the calculation line by comparison to measured values. It should be desirable that such experiment could reproduce as much as possible those conditions estimated for the RRR reactor, still under design in Argentina, having Silicide fuel elements with burnable poison, in the shape of cadmium wires in their structure. We here analyse a possible experiment consisting in the loading of a prototype fuel element with burnable poison in a normally loaded RA-3 core configuration. It would essentially be a standard RA-3 fuel element, having cadmium wires in its frame. This experiment would enable the verification of the prototype behaviour under irradiation, its operation limits and conditions, and particularly, the reactivity safety margins established in Argentine Standards, both calculated and measured. The main part of the experiment would imply some 200 full power days of operation at 5 MW, which would be drastically reduced if the reactor power is increased to 10 MW, as foreseen. We also show that under the proposed conditions, the experiment would not represent a significant penalty to the reactor normal operation. (author)

  16. Safe core management with burnable absorbers in WWERs

    International Nuclear Information System (INIS)

    1996-01-01

    The objective of this TECDOC is to present state of the art information on burnable poisoned fuel during the CRP. It is based on experimental evidence and on the utilization of theoretical models and will help achieve improvements in safety and economy of LWR cores with hexagonal geometries. 149 refs, figs and tabs

  17. Effects of Burnable Absorbers on PWR Spent Nuclear Fuel

    International Nuclear Information System (INIS)

    O'Leary, P.M.; Pitts, M.L.

    2000-01-01

    Burnup credit is an ongoing issue in designing and licensing transportation and storage casks for spent nuclear fuel (SNF). To address this issue, in July 1999, the U.S. Nuclear Regulatory Commission (NRC), Spent Fuel Project Office, issued Interim Staff Guidance-8 (ISG-8), Revision 1 allowing limited burnup credit for pressurized water reactor (PWR) spent nuclear fuel (SNF) to be used in transport and storage casks. However, one of the key limitations for a licensing basis analysis as stipulated in ISG-8, Revision 1 is that ''burnup credit is restricted to intact fuel assemblies that have not used burnable absorbers''. Because many PWR fuel designs have incorporated burnable-absorber rods for more than twenty years, this restriction places an unnecessary burden on the commercial nuclear power industry. This paper summarizes the effects of in-reactor irradiation on the isotopic inventory of PWR fuels containing different types of integral burnable absorbers (BAs). The work presented is illustrative and intended to represent typical magnitudes of the reactivity effects from depleting PWR fuel with different types of burnable absorbers

  18. Analysis of burnable poison in Ford Nuclear Reactor fuel to extend fuel lifetime. Final report, August 1, 1994--September 29, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Burn, R.R.; Lee, J.C.

    1996-12-01

    The objective of the project was to establish the feasibility of extending the lifetime of fuel elements for the Ford Nuclear Reactor (FNR) by replacing current aluminide fuel with silicide fuel comprising a heavier uranium loading but with the same fissile enrichment of 19.5 wt% {sup 235}U. The project has focused on fuel designs where burnable absorbers, in the form of B{sub 4}C, are admixed with uranium silicide in fuel plates so that increases in the control reactivity requirements and peak power density, due to the heavier fuel loading, may be minimized. The authors have developed equilibrium cycle models simulating current full-size aluminide core configurations with 43 {approximately} 45 fuel elements. Adequacy of the overall equilibrium cycle approach has been verified through comparison with recent FNR experience in spent fuel discharge rates and simulation of reactor physics characteristics for two representative cycles. Fuel cycle studies have been performed to compare equilibrium cycle characteristics of silicide fuel designs, including burnable absorbers, with current aluminide fuel. These equilibrium cycle studies have established the feasibility of doubling the fuel element lifetime, with minimal perturbations to the control reactivity requirements and peak power density, by judicious additions of burnable absorbers to silicide fuel. Further study will be required to investigate a more practical silicide fuel design, which incorporates burnable absorbers in side plates of each fuel element rather than uniformly mixes them in fuel plates.

  19. Minor actinide transmutation on PWR burnable poison rods

    International Nuclear Information System (INIS)

    Hu, Wenchao; Liu, Bin; Ouyang, Xiaoping; Tu, Jing; Liu, Fang; Huang, Liming; Fu, Juan; Meng, Haiyan

    2015-01-01

    Highlights: • Key issues associated with MA transmutation are the appropriate loading pattern. • Commercial PWRs are the only choice to transmute MAs in large scale currently. • Considerable amount of MA can be loaded to PWR without disturbing k eff markedly. • Loading MA to PWR burnable poison rods for transmutation is an optimal loading pattern. - Abstract: Minor actinides are the primary contributors to long term radiotoxicity in spent fuel. The majority of commercial reactors in operation in the world are PWRs, so to study the minor actinide transmutation characteristics in the PWRs and ultimately realize the successful minor actinide transmutation in PWRs are crucial problem in the area of the nuclear waste disposal. The key issues associated with the minor actinide transmutation are the appropriate loading patterns when introducing minor actinides to the PWR core. We study two different minor actinide transmutation materials loading patterns on the PWR burnable poison rods, one is to coat a thin layer of minor actinide in the water gap between the zircaloy cladding and the stainless steel which is filled with water, another one is that minor actinides substitute for burnable poison directly within burnable poison rods. Simulation calculation indicates that the two loading patterns can load approximately equivalent to 5–6 PWR annual minor actinide yields without disturbing the PWR k eff markedly. The PWR k eff can return criticality again by slightly reducing the boric acid concentration in the coolant of PWR or removing some burnable poison rods without coating the minor actinide transmutation materials from PWR core. In other words, loading minor actinide transmutation material to PWR does not consume extra neutron, minor actinide just consumes the neutrons which absorbed by the removed control poisons. Both minor actinide loading patterns are technically feasible; most importantly do not need to modify the configuration of the PWR core and

  20. Neutronic analysis of Gd2O3 as burnable poison

    International Nuclear Information System (INIS)

    Lecot, C.A.

    1990-01-01

    For the reactors core design, the use of burnable poisons is one of the options for the control of in excess reactivity and the power form factor. As alternative procedures, the absorbing material may be included in pellets of an inert material or in fuel pellets. Besides, a cladding material and the locations of the fuel elements must be chosen for the first case. The CAREM reactor core design foresees the use of gadolinium oxide (Gd 2 O 3 ) as burnable poison. In this work, a comparative study was made, from the neutronic point of view, among the following alternatives for the poisons location: a) Gd 2 O 3 bars supports in alumina (Al 2 O 3 ), sheathed in steel; b) Gd 2 O 3 bars supports in alumina sheathed in Zry-4; c) Gd 2 O 3 in uranium dioxide (UO 2 ) fuel pellets. (Author) [es

  1. Burnable poison rod for a nuclear reactor fuel assembly

    International Nuclear Information System (INIS)

    Funk, C.E.; Oneufer, A.S.

    1984-01-01

    A burnable poison rod for use in a nuclear reactor fuel assembly which includes concentrically disposed rods having an annular space therebetween which extends the full length of the rods. The inner rod is hollow to permit circulation of coolant therethrough. Annular burnable poison pellets are positioned in the annular space which is closed at both ends by plugs. A spring clip is located in the plenum space above the pellet stack in the rods. The spring clip is of cylindrical configuration having a gap in the material which provides two ends adapted to be squeezed toward each other. A cross section of the clip shows that its ends contain alternating flat and round edges, the round edges conforming to the outer rod inner surface to provide a retentive force which is releasably applied to the pellet stack as it grows during operation in a reactor

  2. Study of gadolinia-doped ceria solid electrolyte surface by XPS

    International Nuclear Information System (INIS)

    Datta, Pradyot; Majewski, Peter; Aldinger, Fritz

    2009-01-01

    Gadolinia-doped ceria (CGO) is an important material to be used as electrolyte for solid oxide fuel cell for intermediate temperature operation. Ceria doped with 10 mol% gadolinia (Ce 0.9 Gd 0.1 O 1.95 ) was prepared by conventional solid state synthesis and found to be single phase by room temperature X-ray diffraction (XRD). The chemical states of the surface of the prepared sample were analyzed by X-ray photoelectron spectroscopy (XPS). Though Gd was present in its characteristic chemical state, Ce was found in both Ce 4+ and Ce 3+ states. Presence of Ce 3+ state was ascribed to the differential yield of oxygen atoms in the sputtering process

  3. Calculation qualification of gadolinium burnable poisons in water reactors

    International Nuclear Information System (INIS)

    Chaucheprat, P.

    1988-01-01

    The work presented in this thesis constitutes the qualification on the one end of Appolo-Neptune scheme for the gadolinium burnable poison in a pressurized water reactor, and on the other end of basis nuclear data on natural gadolinium. This study has permitted to reduce by a factor 3 the actual incertitude on the gadolinium poison comparatively at precisions cited in international benchmarks calculations [fr

  4. Gadolinium burnable absorber optimization by the method of conjugate gradients

    International Nuclear Information System (INIS)

    Drumm, C.R.; Lee, J.C.

    1987-01-01

    The optimal axial distribution of gadolinium burnable poison in a pressurized water reactor is determined to yield an improved power distribution. The optimization scheme is based on Pontryagin's maximum principle, with the objective function accounting for a target power distribution. The conjugate gradients optimization method is used to solve the resulting Euler-Lagrange equations iteratively, efficiently handling the high degree of nonlinearity of the problem

  5. Influence of calcium and lithium on the densification and electrical conductivity of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    Porfirio, Tatiane Cristina

    2011-01-01

    In this work, the use of calcium and lithium as sintering aid to gadolinia-doped ceria was systematically investigated. The main purpose was to verify the influence of these additives on the densification and electrical conductivity of sintered ceramics. Powder compositions containing up to 1.5 mol% (metal basis) of calcium or lithium were prepared by both solid state reaction and oxalate coprecipitation methods. The main characterization techniques were thermal analyses, X-ray diffraction, scanning electron microscopy and electrical conductivity by impedance spectroscopy. Both additives promoted densification of gadolinia-doped ceria. The densification increases with increasing the additive content. Different effects on microstructure and electrical conductivity result from the method of preparation, e.g., solid state reaction or coprecipitation. Calcium addition greatly enhances the grain growth compared to lithium addition. The electrical conductivity of specimens containing a second additive is lower than that of pure gadolinia-doped ceria. Both additives influence the intergranular conductivity and favor the exudation of gadolinium out of the solid solution. (author)

  6. An initial applications study of ceria-gadolinia solid oxide fuel cells: V. 1

    Energy Technology Data Exchange (ETDEWEB)

    Bauen, A.; Hart, D.; Mould, B.

    1998-11-01

    Fuel cells are categorised by their electrolytes, and the solid oxide fuel cell is so called because its electrolyte consists of a solid ceramic oxide. Commonly this has been a form of zirconia, though other materials are now being considered for their different electrical properties. One of these, ceria doped with gadolinia, shows promise for use in lower temperature regimes than zirconia, and may open up different areas of a future market for consideration. This report considers the opportunities for ceria-gadolinia solid oxide fuel cell systems by comparing them with the application requirements in markets where fuel cells may have potential. The advantages and disadvantages of the technology are analysed, together with the state of the art in research and development. The direction in which research effort needs to move to address some of the issues is assessed. The report then draws conclusions regarding the potential of ceria-gadolinia in solid oxide fuel cell systems and in the energy markets as a whole. It should be noted that while this report is an applications study, some technology assessment has been included. Much of this is found in Volume 2. (author)

  7. Special quasirandom structures for gadolinia-doped ceria and related materials

    KAUST Repository

    Wang, Hao

    2012-01-01

    Gadolinia doped ceria in its doped or strained form is considered to be an electrolyte for solid oxide fuel cell applications. The simulation of the defect processes in these materials is complicated by the random distribution of the constituent atoms. We propose the use of the special quasirandom structure (SQS) approach as a computationally efficient way to describe the random nature of the local cation environment and the distribution of the oxygen vacancies. We have generated two 96-atom SQS cells describing 9% and 12% gadolinia doped ceria. These SQS cells are transferable and can be used to model related materials such as yttria stabilized zirconia. To demonstrate the applicability of the method we use density functional theory to investigate the influence of the local environment around a Y dopant in Y-codoped gadolinia doped ceria. It is energetically favourable if Y is not close to Gd or an oxygen vacancy. Moreover, Y-O bonds are found to be weaker than Gd-O bonds so that the conductivity of O ions is improved. © 2012 the Owner Societies.

  8. Report on the evaluation of the tritium producing burnable absorber rod lead test assembly. Revision 1

    International Nuclear Information System (INIS)

    1997-03-01

    This report describes the design and fabrication requirements for a tritium-producing burnable absorber rod lead test assembly and evaluates the safety issues associated with tritium-producing burnable absorber rod irradiation on the operation of a commercial light water reactor. The report provides an evaluation of the tritium-producing burnable absorber rod design and concludes that irradiation can be performed within U.S. Nuclear Regulatory Commission regulations applicable to a commercial pressurized light water reactor

  9. The research on burnup characteristic of doping burnable poison in PWR

    International Nuclear Information System (INIS)

    Qiang Shenglong; Qin Dong; Chai Xiaoming; Yao Dong

    2014-01-01

    In PWR core design, burnable poisons are usually used for reactive compensation and power flatten. The choice of burnable poisons and how to match burnup would be the key-points for a long-life core design. We study the burnup character of doping burnable poisons (such as natural element, manual nuclide and soluble boron) in the PWR by the core burnup code MOI based on Monte Carlo method. The results show that Hf, Er and Eu doping burnable poison would be applicable for the nuclear design research on the long-life PWR core. (authors)

  10. Characterization of gadolinia-doped ceria with manganese addition synthesized by the cation complexation technique; Caracterizacao de ceria-gadolinia e ceria-gadolinia-manganes sintetizados pelo metodo de complexacao de cations

    Energy Technology Data Exchange (ETDEWEB)

    Yang, J.D.; Muccillo, R.; Muccillo, E.N.S., E-mail: enavarro@usp.b [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais; Rocha, R.A. [Universidade Federal do ABC (CEMCSA/UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas

    2010-07-01

    Ceria-based compounds may be used for several technological applications like catalysts, grinding media and materials for electrolyte and electrodes in solid oxide fuel cells. For most of these applications fine powders are required. In this work, nanostructured ceria powders containing 20 mol % gadolinia with and without manganese addition were synthesized by the cation complexation technique. The prepared powders were calcined at 600 deg C for thermal decomposition of the metal citrate precursors. Results of X-ray diffraction, scanning electron microscopy and specific surface area evidenced the role of manganese on physical characteristics of the nanostructured materials. The cation complexation technique revealed to be a promising method for obtaining nanostructured powders with high yield and suitable physical properties for several technological applications. (author)

  11. Managing the reactivity excess of the gas turbine-modular helium reactor by burnable poison and control rods

    International Nuclear Information System (INIS)

    Talamo, Alberto

    2006-01-01

    The gas turbine-modular helium reactor coupled to the deep burn in-core fuel management strategy offers the extraordinary capability to incinerate over 50% of the initial inventory of fissile material. This extraordinary feature, coming from an advanced and well tested fuel element design, which takes advantage of the TRISO particles technology, is maintained while the reactor is loaded with the most different types of fuels. In the present work, we assumed the reactor operating at the equilibrium of the fuel composition, obtained by a 6 years irradiation of light water reactor waste, and we investigated the effects of the introduction of the burnable poison and the control rods; we equipped the core with all the three types of control rods: operational, startup and shutdown ones. We employed as burnable poison natural erbium, due to the 167 Er increasing neutron capture microscopic cross-section in the energy range where the neutron spectrum exhibits the thermal peak; in addition, we utilized boron carbide, with 90% enrichment in 1 B, as the absorption material of the control rods. Concerning the burnable poison studies, we focused on the k eff value, the 167 Er mass during burnup, the influence of modifying the radius of the BISO particles kernel and the fuel and moderator coefficients of temperature. Concerning the control rods studies, we investigated the reactivity worth, the changes in the neutron flux profile due to a partial insertion, the influence of modifying the radius of the BISO particles kernel and the β eff , at the beginning of the operation

  12. Managing the reactivity excess of the gas turbine-modular helium reactor by burnable poison and control rods

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)]. E-mail: alby@neutron.kth.se

    2006-01-15

    The gas turbine-modular helium reactor coupled to the deep burn in-core fuel management strategy offers the extraordinary capability to incinerate over 50% of the initial inventory of fissile material. This extraordinary feature, coming from an advanced and well tested fuel element design, which takes advantage of the TRISO particles technology, is maintained while the reactor is loaded with the most different types of fuels. In the present work, we assumed the reactor operating at the equilibrium of the fuel composition, obtained by a 6 years irradiation of light water reactor waste, and we investigated the effects of the introduction of the burnable poison and the control rods; we equipped the core with all the three types of control rods: operational, startup and shutdown ones. We employed as burnable poison natural erbium, due to the {sup 167}Er increasing neutron capture microscopic cross-section in the energy range where the neutron spectrum exhibits the thermal peak; in addition, we utilized boron carbide, with 90% enrichment in {sup 1}B, as the absorption material of the control rods. Concerning the burnable poison studies, we focused on the k {sub eff} value, the {sup 167}Er mass during burnup, the influence of modifying the radius of the BISO particles kernel and the fuel and moderator coefficients of temperature. Concerning the control rods studies, we investigated the reactivity worth, the changes in the neutron flux profile due to a partial insertion, the influence of modifying the radius of the BISO particles kernel and the {beta} {sub eff}, at the beginning of the operation.

  13. Burnable poison management in light water reactor lattices

    Energy Technology Data Exchange (ETDEWEB)

    Buenemann, D; Mueller, A

    1970-07-01

    For a better reactivity control and power flattening as well as for an increase in dynamic stability the use of burnable poisons in light water reactors has been considered. The main goals for a burnable poison management and its technological realisation are discussed. The poison is assumed to be in the form of separate poison rods or homogeneous or inhomogeneous poisoning in the fuel rods. A new concept with a central poison rod within the fuel rod is discussed. The balance-equation for the needed concentration of burnable poisons for reactivity central as well as the problems of optimization of lumped poisons are treated in connection with the fuel lattice burnup. A first approximation for the design is found. For the calculation of the microburnup of lumped poison and fuel the special code NEUTRA has been developed. The burnup-equation can be chosen either in a simplified burnup-version with 2 pseudo fission products for each fissionable isotope or with an extended system of burnup equations to be used at sophisticated calculations. These burnup equations are coupled to S{sub N}-routines optionally for cylindrical or x-y-geometry for the proper calculation of the microscopic isotope density-, flux-, and power distributions. The theoretical predictions have been checked by means of special experiments so as to determine the accuracy of the computations. Even for a relatively long burnup of the fuel the predicted values are found to be within the experimental error in the case of lumped rods containing a cadmium-alloy or boron carbide. (auth)

  14. Impact of burnable absorber Gd on nuclide composition for VVER-440 fuel (Gd-2)

    International Nuclear Information System (INIS)

    Zajac, R.; Chrapciak, V.

    2010-01-01

    The latest version of Russian fuel VVER-440 includes burnable absorber in 6 pins. In this article is impact of burnable absorber on nuclide composition and criticality analyzed. In part 1 was analyzed whole burnup interval 0-50 MWd/kgU. In present part 2 are detailed analysis only for first cycle (burnup 0-10 MWd/kgU). (Authors)

  15. Effects of the burnable poison heterogeneity on the long term control of excess of reactivity

    International Nuclear Information System (INIS)

    Talamo, Alberto

    2006-01-01

    According to the different geometry shape, the theory of black burnable particles predicts that the evolution of the poison macroscopic absorption cross section is exponentially, quadratic or linear when the burnable poison is displaced in homogeneous distribution, microspheres or needlecylinders heterogeneous distributions, respectively. In the present studies, we took advantage of the Monte Carlo Continuous Energy Burnup Code MCB to verify the black burnable particles theory on the Gas Turbine - Modular Helium Reactor fuelled by military plutonium at the year the fuel reaches the equilibrium composition; we investigated 8 different burnable poisons, B, Cd, Er, Eu, Gd, Dy, Hf and Sm, in three different geometry configurations and we have found that the numerical results qualitatively match the theory predictions when burnable poisons are disposed in small particles

  16. Effects of the burnable poison heterogeneity on the long term control of excess of reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Talamo, Alberto [Department of Nuclear and Reactor Physics, Royal Institute of Technology - KTH, Roslagstullsbacken 21, S-10691, Stockholm (Sweden)]. E-mail: alby@neutron.kth.se

    2006-06-15

    According to the different geometry shape, the theory of black burnable particles predicts that the evolution of the poison macroscopic absorption cross section is exponentially, quadratic or linear when the burnable poison is displaced in homogeneous distribution, microspheres or needlecylinders heterogeneous distributions, respectively. In the present studies, we took advantage of the Monte Carlo Continuous Energy Burnup Code MCB to verify the black burnable particles theory on the Gas Turbine - Modular Helium Reactor fuelled by military plutonium at the year the fuel reaches the equilibrium composition; we investigated 8 different burnable poisons, B, Cd, Er, Eu, Gd, Dy, Hf and Sm, in three different geometry configurations and we have found that the numerical results qualitatively match the theory predictions when burnable poisons are disposed in small particles.

  17. Feasibility of using gadolinium as a burnable poison in PWR cores. Final report

    International Nuclear Information System (INIS)

    Rothleder, B.M.

    1981-02-01

    As an alternative to the use of lumped burnable absorbers in PWR cores, distributed burnable absorbers are being considered for generic application. These burnable absorbers take the form of Gd 2 O 3 mixed with UO 2 in selected fuel rods (as is currently done in BWR cores). The work discussed herein concerns a three-dimensional feasibility study of the use of such distributed burnable absorbers in PWR cores. This study of distributed burnable absorbers was performed for the first cycle of a typical current design PWR using the following steps: analysis of a generic reference core design; determination of gadolinium assembly designs; determination of a generic gadolinium core design; evaluation of feasibility by examining selected parameters; and redesign of the generic gadolinium core, using axial zoning

  18. Application of boron and gadolinium burnable poison particles in UO2 and PUO2 fuels in HTRs

    International Nuclear Information System (INIS)

    Kloosterman, J.L.

    2003-01-01

    Burnup calculations have been performed on a standard HTR fuel pebble (fuel zone with radius of 2.5 cm surrounded with a 0.5 cm thick graphite layer) and burnable poison particles (BPPs) containing B 4 C made of pure 10 B or containing Gd 2 O 3 made of natural Gd. Two types of fuel were considered: UO 2 fuel made of 8% enriched uranium and PuO 2 fuel made of plutonium from LWR spent fuel. The radius of the BPP and the number of particles per fuel pebble were varied to find the flattest reactivity-to-time curve. For the UO 2 fuel, the reactivity swing is lowest (around 2%) for BPPs made of B 4 C with radius of 75 μm. In this case around 1070 BPPs per fuel pebble are needed. For the PuO 2 fuel to get a reactivity swing below 4%, the optimal radius of the BPP is the same, but the number of particles per fuel pebble should be around 1600. The optimal radius of the Gd 2 O 3 particles in the UO 2 fuel is about 10 times that of the B 4 C particles. The reactivity swing is around 3% when each fuel pebble contains only 9 BPPs with radius of 840 μm. The results of the Gd particles illustrate nicely the usage of black burnable poison particles introduced by Van Dam [Ann. Nuclear Energy 27 (2000) 733

  19. Preparation and characterization of ceramic neutron absorbers based on dysprosia and gadolinia

    International Nuclear Information System (INIS)

    Burgos, F.; Oliber, E.; Leiva S; Lestani, H.; Malachevsky, M.T.; Taboada, H.; D'Ovidio, C.

    2012-01-01

    Among the elements of the lanthanide series, dysprosium and gadolinium have interesting nuclear properties. Due to their high thermal neutron absorption cross-section they are good neutron absorbers. The only compounds suitable for nuclear use are their oxides, dysprosia (Dy 2 O 3 ) and gadolinia (Gd 2 O 3 ). To fabricate neutron absorbers diluted in an inert matrix, e.g. alumina (Al 2 O 3 ), it is relevant to study the preparation of a ceramic compound based on alumina (Al 2 O 3 ) and dysprosia or gadolinia. In this work, we characterize four different nominal compositions with high contents of gadolinia and dysprosia: (a) (45 wt% Dy 2 O 3 , 55 wt% Al 2 O 3 ), (b) (93 wt% Dy 2 O 3 , 7 wt% Al 2 O 3 ), (c) (50 wt% Gd 2 O 3 , 50 wt% Al 2 O 3 ) and (d) (90 wt% Gd 2 O 3 , 10 wt% Al 2 O 3 ). These compositions were selected as their stoichiometry correspond to the eutectic phases found in the respective phase diagrams, so as to attain sinterization at lower temperatures of approximately 1700 o C in air. The investigated parameters are the geometrical density of the pellets, the microstructure and the phases observed using x-ray diffraction. Contraction of the pellets was obtained by measuring the volumetric change between the green and the sintered samples. It was observed that the relative contraction was the same both in thickness and diameter. We discuss the eutectic phase formation and densification observed for the different compositions (author)

  20. Spanish collaboration in the OECD Halden Reactor Project research on Gadolinia Fuel

    International Nuclear Information System (INIS)

    Horvath, M.; Munoz-Reja, C.; Tverberg, T.; Jenssen, H. K.

    2010-01-01

    Safe and reliable operation of nuclear power plants benefit from research and development advances and related technical solutions. One research platform is the OECD Halden Reactor Project (HRP). HRP is a joint undertaking of national organisations in 18 countries sponsoring a jointly financed programme under the auspices of the OECD - Nuclear Energy Agency (NEA). As a member state, Spain is participating HRP research programs with ENUSA as a partner in the fuel research programs. Improving the NPP operations, fuel cycles were designed to increase fuel burnup. Higher fuel burnup reduces the number of spent fuel assemblies and thus the costs of new fuel as well as the costs of back-end management. Higher burnup is reached either by prolonging the reactor cycles or by increasing the number of reactor cycles for the fuel in the core. Both ways entail additional requirements concerning fuel enrichment and burnable absorbers as additives and adjustments on the cladding material properties, such as mechanical treatment and chemical composition of the alloys. For these demands and needs ENUSA promotes the research on high burnup effects, gadolinium doped fuels and cladding material behaviour under irradiation. Various experiments, called IFA, are developed and performed also by providing materials. ENUSA collaborates with HRP on various experiments investigating the fuel densification and swelling, fission gas release, pressure limits on UO 2 and (U,Gd)O 2 fuels (IFA-504, -515, -636, -681); the cladding creep, lift-off, corrosion and hydrides on different tubing materials (IFA-567, -610, -638); instrumentation of the experiments, especially on pre-irradiated materials (IFA-533). These experiments are combined with model calculations to improve predictions for higher burnups and to maintain safety margins (IFA-515, -636, -681). Besides these unique in-pile experiments PIEs are performed as well on fuel and structural materials to complete the scope of these studies (IFA

  1. Generalized pin factor methodology for LWR reload cores with discrete burnable absorbers

    International Nuclear Information System (INIS)

    Hah, C.J.; Hideki Matsumoto; Toshikazu Ida; Lee, C.; Chao, Y.A.

    2005-01-01

    Discrete burnable absorbers are used to suppress excess reactivity as well as peak pin power in an assembly. After the burn-out of absorption material, discrete burnable absorbers are usually removed from assembly guide tubes for the next cycle. For that case, the pin factors with discrete burnable absorbers cannot be used since the assembly configuration is physically changed. The pin factors without discrete burnable absorbers also have noticeable deviation from the actual case because they do not take into account the history effect due to the residence of discrete burnable absorbers for the previous cycle. In this paper, the generalized pin factor (GPF) method is developed to accurately predict pin powers by considering the history effect. The method uses a second-order polynomial function to approximate the history effect which builds up during the residence of burnable absorber material and employs a linear approximation to simulate the decay of the history effect after discrete burnable absorbers are removed. The verification results from Westinghouse Vantage- 5H assemblies with WABAs showed that pin power errors were significantly reduced by using the GPF. (authors)

  2. High-temperature conversion of methane on a composite gadolinia-doped ceria-gold electrode

    DEFF Research Database (Denmark)

    Marina, O.A.; Mogensen, Mogens Bjerg

    1999-01-01

    Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials such as n......Direct electrochemical oxidation of methane was attempted on a gadolinia-doped ceria Ce(0.6)Gd(0.4)O(1.8) (CG4) electrode in a solid oxide fuel cell using a porous gold-CG4 mixture as current collector Gold is relatively inert to methane in contrast to other popular SOFC anode materials...... such as nickel and platinum. CG4 was found to exhibit a low electrocatalytic activity for methane oxidation as well as no significant reforming activity implying that the addition of an electrocatalyst or cracking catalyst to the CG4 anode is required for SOFC operating on methane. The methane conversion...... observed at the open-circuit potential and low anodic overpotentials seems to be due to thermal methane cracking in the gas phase and on the alumina surfaces in the cell housing. At high anodic overpotentials, at electrode potentials where oxygen evolution was expected to take place, the formation of CO(2...

  3. Nanostructured PLD-grown gadolinia doped ceria: Chemical and structural characterization by transmission electron microscopy techniques

    DEFF Research Database (Denmark)

    Rodrigo, Katarzyna Agnieszka; Wang, Hsiang-Jen; Heiroth, Sebastian

    2011-01-01

    The morphology as well as the spatially resolved elemental and chemical characterization of 10 mol% gadolinia doped ceria (CGO10) structures prepared by pulsed laser deposition (PLD) technique are investigated by scanning transmission electron microscopy accompanied with electron energy loss spec......, indicate apparent variation of the ceria valence state across and along the film. No element segregation to the grain boundaries is detected. These results are discussed in the context of solid oxide fuel cell applications.......The morphology as well as the spatially resolved elemental and chemical characterization of 10 mol% gadolinia doped ceria (CGO10) structures prepared by pulsed laser deposition (PLD) technique are investigated by scanning transmission electron microscopy accompanied with electron energy loss...... spectroscopy and energy dispersive X-ray spectroscopy. A dense, columnar and structurally inhomogeneous CGO10 film, i.e. exhibiting grain size refinement across the film thickness, is obtained in the deposition process. The cerium M4,5 edges, used to monitor the local electronic structure of the grains...

  4. Depletion of gadolinium burnable poison in a PWR assembly with high burnup fuel

    Energy Technology Data Exchange (ETDEWEB)

    Refeat, Riham Mahmoud [Nuclear and Radiological Regulatory Authority (NRRA), Cairo (Egypt). Safety Engineering Dept.

    2015-12-15

    A tendency to increase the discharge burnup of nuclear fuel for Advanced Pressurized Water Reactors (PWR) has been a characteristic of its operation for many years. It will be able to burn at very high burnup of about 70 GWd/t with UO{sub 2} fuels. The U-235 enrichment must be higher than 5 %, which leads to the necessity of using an extremely efficient burnable poison like Gadolinium oxide. Using gadolinium isotope is significant due to its particular depletion behavior (''Onion-Skin'' effect). In this paper, the MCNPX2.7 code is used to calculate the important neutronic parameters of the next generation fuels of PWR. K-infinity, local peaking factor and fission rate distributions are calculated for a PWR assembly which burn at very high burnup reaching 70 GWd/t. The calculations are performed using the recently released evaluated Gadolinium cross section data. The results obtained are close to those of a LWR next generation fuel benchmark problem. This demonstrates that the calculation scheme used is able to accurately model a PWR assembly that operates at high burnup values.

  5. A model for fuel shuffling and burnable absorbers optimization in low leakage PWRs

    International Nuclear Information System (INIS)

    Zavaljevski, N.

    1990-01-01

    A nonlinear model for the simultaneous optimization of fuel shuffling and burnable absorbers in PWRs is formulated using the depletion perturbation theory. The sensitivity coefficients are defined in a new way, using a macroscopic burnup model coupled with the explicit burnable absorbers depletion equation. Since first-order perturbation theory is limited to small changes in burnable absorber concentration, the associated control variable is continuous, with a constraint on maximal increment. Fuel shuffling is described by Boolean variables. Thus a special case of a mixed-integer quadratic programming problem is obtained, since the interaction of fuel and absorber optimization is considered. (author)

  6. Design and test of the borosilicate glass burnable poison rod for Qinshan nuclear power plant core

    International Nuclear Information System (INIS)

    Huang Jinhua; Sun Hanhong

    1988-08-01

    Material for the burnable poison of Qinshan Nuclear Power Plant core is GG-17 borosilicate glass. The chemical composition and physico-chemical properties of GG-17 is very close to Pyrex-7740 glass used by Westinghouse. It is expected from the results of the experiments that the borosilicate glass burnable poison rod can be successfully used in Qinshan Nuclear Power Plant due to good physical, mechanical, corrosion-resistant and irradiaton properties for both GG-17 glass and cold-worked stainless steel cladding. Change of material for burnable poison from boron-bearing stainless steel to borosilicate glass will bring about much more economic benefit to Qinshan Naclear Power Plant

  7. First results on study of gadolinium as burnable absorber

    International Nuclear Information System (INIS)

    Abbate, Maximo J.; Sbaffoni, Maria M.

    2000-01-01

    Following on with the work included in the 'Burnable absorbers research plan' several experiments were carried out oriented to determine Ga 2 O 3 burn up. Cold tests were performed and samples were irradiated in the RA-3 reactor. In this paper, some calculated values are presented together with their comparisons with experimental ones. The parameters foreseen for performing the experiments were verified and also the predictions on burn up of uranium and gadolinium isotopes concentrations. These results imply that the nuclear data of these isotopes included in the library are satisfactory. Next steps will be to measure other isotopes concentrations, gamma spectrum, and the irradiation of one pellet to determine self shielding effects in order to obtain effective cross sections i.e. for CAREM geometry. (author)

  8. The treatment of burnable poison pins in LWRWIMS

    International Nuclear Information System (INIS)

    Halsall, M.J.

    1982-12-01

    This report describes an investigation into the modelling approximations normally made when the LWR lattice code LWRWIMS is used for design calculations on assemblies containing burnable poison pins. Parameters investigated include energy group structure, intervals between calculations in MWd/te and spatial subdivision of the poison pins. An estimate is made of the effect of using pin-cell smearing with diffusion theory for the assembly geometry, instead of a more exact heterogeneous transport theory calculation. The influence on reactivity of the minor gadolinium isotopes 152, 154, 156, 158 and 160 in a poison pin dominated by the isotopes 155 and 157 is presented, and finally, recommendations on the use of LWRWIMS for this type of calculation are made. (author)

  9. Incorporation of Integral Fuel Burnable Absorbers Boron and Gadolinium into Zirconium-Alloy Fuel Clad Material

    International Nuclear Information System (INIS)

    Sridharan, K.; Renk, T.J.; Lahoda, E.J.; Corradini, M.L

    2004-01-01

    Long-lived fuels require the use of higher enrichments of 235U or other fissile materials. Such high levels of fissile material lead to excessive fuel activity at the beginning of life. To counteract this excessive activity, integral fuel burnable absorbers (IFBA) are added to some rods in the fuel assembly. The two commonly used IFBA elements are gadolinium, which is added as gadolinium-oxide to the UO2 powder, and boron, which is applied as a zirconium-diboride coating on the UO2 pellets using plasma spraying or chemical vapor deposition techniques. The incorporation of IFBA into the fuel has to be performed in a nuclear-regulated facility that is physically separated from the main plant. These operations tend to be very costly because of their small volume and can add from 20 to 30% to the manufacturing cost of the fuel. Other manufacturing issues that impact cost and performance are maintaining the correct levels of dosing, the reduction in fuel melting point due to gadolinium-oxide additions, and parasitic neutron absorption at fuel's end-of-life. The goal of the proposed research is to develop an alternative approach that involves incorporation of boron or gadolinium into the outer surface of the fuel cladding material rather than as an additive to the fuel pellets. This paradigm shift will allow for the introduction of the IFBA in a non-nuclear regulated environment and will obviate the necessity of additional handling and processing of the fuel pellets. This could represent significant cost savings and potentially lead to greater reproducibility and control of the burnable fuel in the early stages of the reactor operation. The surface alloying is being performed using the IBEST (Ion Beam Surface Treatment) process developed at Sandia National Laboratories. IBEST involves the delivery of energetic ion beam pulses onto the surface of a material, near-surface melting, and rapid solidification. The non-equilibrium nature of such processing allows f or surface

  10. Effects of sintering atmosphere and initial particle size on sintering of gadolinia-doped ceria

    International Nuclear Information System (INIS)

    Batista, Rafael Morgado

    2014-01-01

    The effects of the sintering atmosphere and initial particle size on the sintering of ceria containing 10 mol% gadolinia (GdO 1.5 ) were systematically investigated. The main physical parameter was the specific surface area of the initial powders. Nanometric powders with three different specific surface areas were utilized, 210 m 2 /g, 36,2 m 2 /g e 7,4 m 2 /g. The influence on the densification, and micro structural evolution were evaluated. The starting sintering temperature was verified to decrease with increasing on the specific surface area of raw powders. The densification was accelerated for the materials with smaller particle size. Sintering paths for crystallite growth were obtained. Master sintering curves for gadolinium-doped ceria were constructed for all initial powders. A computational program was developed for this purpose. The results for apparent activation energy showed noticeable dependence with specific surface area. In this work, the apparent activation energy for densification increased with the initial particle size of powders. The evolution of the particle size distributions on non isothermal sintering was investigated by WPPM method. It was verified that the grain growth controlling mechanism on gadolinia doped ceria is the pore drag for initial stage and beginning of intermediate stage. The effects of the sintering atmosphere on the stoichiometry deviation of ceria, densification, microstructure evolution, and electrical conductivity were analyzed. Inert, oxidizing, and reducing atmospheres were utilized on this work. Deviations on ceria stoichiometry were verified on the bulk materials. The deviation verified was dependent of the specific surface area and sintering atmosphere. Higher reduction potential atmospheres increase Ce 3+ bulk concentration after sintering. Accelerated grain growth and lower electrical conductivities were verified when reduction reactions are significantly present on sintering. (author)

  11. Study of burnable poison in the dupic cycle

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Clarysson A.M. da; Almeida, Michel C.B. de; Faria, Rochkhudson B. de; Moreira, Arthur P.C.; Pereira, Claubia, E-mail: clarysson@nuclear.ufmg.br, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    Recent studies confirm the potential of using reprocessed PWR (Pressurized Water Reactor) fuels in the CANDU (Canada Deuterium Uranium) reactor fuel cycle. An important proposal is the 'Direct Use of spent PWR fuel In CANDU' (DUPIC) cycle, where spent fuels from a PWR are packaged into a CANDU fuel bundle with only mechanical reprocessing (cut into pieces) but no chemical reprocessing. The fissile contents of the spent fuel from Pressurized Water Reactor (PWR) are about 1.5 wt%, which is higher than that of the fuel of CANDU. When this reactor is reload with reprocessed fuel, the reactivity of system will increase and this behavior may affect the safety parameters of reactor. To reduce the initial reactivity, Burnable Poison (BP) can be inserted in the fuel bundle of CANDU. In this way, the present paper evaluates the insertion of the different types of BP considering the DUPIC cycle. The following BPs were evaluated: Boron, Cadmium, Dysprosium, Erbium, Europium, Gadolinium, Hafnium and Samarium. The goal is to verify the neutronic behavior of the fuel bundle at steady state and during the reactor burnup. The SCALE 6.0 (Standardized Computer Analyses for Licensing Evaluation) code was employed to model a standard CANDU-6 fuel element. (author)

  12. Optimizing the use of gadolinium as burnable poison in nuclear fuel: towards a boron free PWR

    International Nuclear Information System (INIS)

    Pieck, D.

    2013-01-01

    Reactivity excess in Nuclear Power Plants is controlled by reactor's active systems: boric acid dilution and control rods. Alternatively, negative reactivity insertion can be made in a passive way using burnable poisons, i.e. neutron absorbers, this is the case of gadolinium (Gd). In the industrial framework of U 235 enrichment increase and boric acid restraint, the goal of this thesis is to optimize the distribution of gadolinium in UO 2 ceramics to obtain a high-performance provision of negative reactivity in Pressurized Water Reactors. In this sense, the work is focus on new gadolinium-rich materials. Thus, U-Gd-O phase diagram was explored in the field of high Gd contents. Two cubic phases were found and characterized: the C1 and C2 phases. With the aim of an industrial application, C1 phase was selected as candidate for Gd addition into UO 2 pellets. The optimal distribution of C1 phase within a nuclear fuel assembly was studied using APOLLO 2.8 neutron transport code. Parametric calculations were performed. These neutronic studies have ends in a successful 'concept of poisoned pellet'. Finally, some prototype pellets following this concept were made in laboratory to proof it feasibility. All the obtained results shows that the proposed concept of a neutro-phage C1-phase coating on UO 2 pellets is a convenient way to reduce reactivity excess within the framework of long irradiation cycles. This concept could be potentially applied in industrial scale. Consequently a patent application process was initiated.(author) [fr

  13. Preliminary Nuclear Analysis for the HANARO Fuel Element with Burnable Absorber

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Chul Gyo; Kim, So Young; In, Won Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    Burnable absorber is used for reducing reactivity swing and power peaking in high performance research reactors. Development of the HANARO fuel element with burnable absorber was started in the U-Mo fuel development program at HANARO, but detailed full core analysis was not performed because the current HANARO fuel management system is uncertain to analysis the HANARO core with burnable absorber. A sophisticated reactor physics system is required to analysis the core. The McCARD code was selected and the detailed McCARD core models, in which the basic HANARO core model was developed by one of the McCARD developers, are used in this study. The development of nuclear fuel requires a long time and correct developing direction especially by the nuclear analysis. This paper presents a preliminary nuclear analysis to promote the fuel development. Based on the developed fuel, the further nuclear analysis will improve reactor performance and safety. Basic nuclear analysis for the HANARO and the AHR were performed for getting the proper fuel elements with burnable absorber. Addition of 0.3 - 0.4% Cd to the fuel meat is promising for the current HANARO fuel element. Small addition of burnable absorber may not change any fuel characteristics of the HANARO fuel element, but various basic tests and irradiation tests at the HANARO core are required.

  14. The influence of petrography, mineralogy and chemistry on burnability and reactivity of quicklime produced in Twin Shaft Regenerative (TSR) kilns from Neoarchean limestone (Transvaal Supergroup, South Africa)

    Science.gov (United States)

    Vola, Gabriele; Sarandrea, Luca; Della Porta, Giovanna; Cavallo, Alessandro; Jadoul, Flavio; Cruciani, Giuseppe

    2017-12-01

    This study evaluates the influence of chemical, mineralogical and petrographic features of the Neoarchean limestone from the Ouplaas Mine (Griqualand West, South Africa) on its burnability and quicklime reactivity, considering the main use as raw material for high-grade lime production in twin shaft regenerative (TSR) kilns. This limestone consists of laminated clotted peloidal micrite and fenestrate microbial boundstone with herringbone calcite and organic carbon (kerogen) within stylolites. Diagenetic modifications include hypidiotopic dolomite, micrite to microsparite recrystallization, stylolites, poikilotopic calcite, chert and saddle dolomite replacements. Burning and technical tests widely attest that the Neoarchean limestone is sensitive to high temperature, showing an unusual and drastically pronounced sintering or overburning tendency. The slaking reactivity, according to EN 459-2 is high for lime burnt at 1050 °C, but rapidly decreases for lime burnt at 1150 °C. The predominant micritic microbial textures, coupled with the organic carbon, are key-factors influencing the low burnability and the high sintering tendency. The presence of burial cementation, especially poikilotopic calcite, seems to promote higher burnability, either in terms of starting calcination temperature, or in terms of higher carbonate dissociation rate. In fact, the highest calcination velocity determined by thermal analysis is consistent with the highest slaking reactivity of the lower stratum of the quarry, enriched in poikilotopic calcite. Secondly, locally concentered dolomitic marly limestones, and sporadic back shales negatively affects the quicklime reactivity, as well. This study confirms that a multidisciplinary analytical approach is essential for selecting the best raw mix for achieving the highest lime reactivity in TSR kilns.

  15. Feasibility study of 24-month cycle using enriched Gadolinium as burnable poison for OPR1000

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Sang-Rae; Shin, Ho-Cheol [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    All of cobalt-60 sources are imported to Korea. CANDU units are generally used to produce cobalt-60 at Bruce and Point Lepreau in Canada and Embalse in Argentina. China has started production of cobalt-60 using its CANDU 6 Qinshan Phase III nuclear power plant in 2009. For cobalt-60 production, the reactor's full complement of stainless steel adjusters is replaced with neutronically equivalent cobalt-59 adjusters, which are essentially invisible to reactor operation. With its very high neutron flux and optimized fuel burn-up, the CANDU has a very high cobalt-60 production rate in a relatively short time. This makes CANDU an excellent vehicle for bulk cobalt-60 production. Several studies have been performed to produce cobalt-60 using adjuster rod at Wolsong nuclear power plant. This study proposed new concept for producing cobalt-60 and performed the feasibility study. Bundle typed cobalt loading concept is proposed and evaluated the feasibility to fuel management without physics and system design change. The requirement to load cobalt bundle to the core was considered and several channels are nominated. The production of cobalt-60 source is very depend on the flux level and burnup directly.

  16. MCNP apply in calculating reactor critical coefficient Keff under the changing of the burnable poison rod

    International Nuclear Information System (INIS)

    Wang Xinghua; Zhou Sichun; Zhang Qingxian; Zhao Feng; Liu Jun; Zhu Jian

    2013-01-01

    Taking Qinshan nuclear power plant as an example, in this paper, Monte Carlo method was used in the MCNP procedures for the establishment of nuclear power station simulation model, construct the reactor pressure vessel and vessel core component composition and arrangement, KCODE card was used to calculate the effect of the number and the location of burnable poison control rod factor K eff by the boron acid. The calculation results show that, with the increasing in the number of burnable poison control rod value-added factor K eff shown a downward trend, and with the burnable poison control rod from the dense to sparse, which K eff will be decreasing slowly. This condition is consistent with the theoretical. (authors)

  17. Nuclear reactor core having nuclear fuel and composite burnable absorber arranged for power peaking and moderator temperature coefficient control

    International Nuclear Information System (INIS)

    Kapil, S.K.

    1992-01-01

    This patent describes a burnable absorber coated nuclear fuel. It comprises a nuclear fuel substrate containing a fissionable material; and an outer burnable absorber coating applied on an outer surface of the substrate; the outer absorber coating being composed of an inner layer of a boron-bearing material except for erbium boride and an outer layer of an erbium material

  18. Group constants calculation for fuel assemblies containing burnable absorbers; Prorachun grupnih konstanti gorivnih elemenata koji sadrzhe sagorive apsorbere

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, B [Institut Rudjer Boskovic, Zagreb (Yugoslavia); Pevec, D [Elektrotehnicki Fakultet, Zagreb Univ. (Yugoslavia); Urli, N; Shmuc, T [Institut Rudjer Boskovic, Zagreb (Yugoslavia)

    1988-07-01

    The upgrading of the computer code package PSU-LEOPARD/MCRAC is described. The upgraded package enables modelling of fuel assemblies containing burnable absorbers in the form of borosilicate glass rodlets, or, integral fuel burnable absorbers. The package is tested using the NPP Krsko core data. (author)

  19. Nuclear reactor core having nuclear fuel and composite burnable absorber arranged for power peaking and moderator temperature coefficient control

    International Nuclear Information System (INIS)

    Kapil, S.K.

    1991-01-01

    This patent describes a nuclear reactor core. It comprises a first group of fuel rods containing fissionable material and being free of burnable absorber material; and a second group of fuel rods containing fissionable material and first and second burnable absorber material; the first burnable absorber material being a boron-bearing material which does not contain erbium and the second burnable absorber material being an erbium material; the first and second burnable absorber materials being in the form of an outer coating on the fissionable material, the outer coating being composed of an inner layer of one of the boron-bearing material which does not contain erbium and the erbium material and an outer layer of the other of the boron-bearing material which does not contain erbium and the erbium material

  20. Reactivity and neutron flux measurements in IPEN/MB-01 reactor with B4C burnable poison

    International Nuclear Information System (INIS)

    Fer, Nelson Custodio; Moreira, Joao Manoel Losada

    2000-01-01

    Burnable poison rods, made of B 4 C- Al 2 O 3 pellets with 5.01 mg/cm 3 10 B concentration, have been manufactured for a set of experiments in the IPEN/MB-01 zero-power reactor. Several core parameters which are affected by the burnable poisons rods have been measured. The principal results, for the situation in which the burnable poison rods are located near the absorber rods of a control rod, are they cause a 29% rod worth shadowing, a reduction of 39% in the local void coefficient of reactivity, a reduction of 4.8% in the isothermal temperature coefficient of reactivity, and a reduction of 9% in the thermal neutron flux in the region where the burnable poison rods are located. These experimental results will be used for the validation of burnable poison calculation methods in the CTMSP. (author)

  1. Optimization of burnable poison disposition for in-core fuel assemblies

    International Nuclear Information System (INIS)

    Zhong Wenfa; Luo Rong; Zhou Quan

    1997-09-01

    The optimization of the burnable poison disposition in the initial core loading of the 200 MW nuclear heating reactor (NHR-200), is studied. The mass fraction of the burnable poison is used as the control variable with the objective to minimize the power peaking factor. The flexible tolerance method is used to solve the nonlinear programming optimal problem. The optimization method can be used in reactor physics design, and get a new pattern of initial core which is of reference value. (2 refs., 8 figs., 1 tab.)

  2. The manufacture process and properties of (U, Gd)O2 burnable poisonous fuel pellets

    International Nuclear Information System (INIS)

    Yi Wei; Tang Yueming; Dai Shengping; Yang Youqing; Zuo Guoping; Wu Shihong; Gu Xiaofei; Gu Mingfei

    2006-03-01

    The main properties of important raw powder materials used in the (U, Gd)O 2 burnable poisonous fuel pellets production line of NPIC are presented. The powders included UO 2 , Gd 2 O 3 , (U, Gd) 3 O 8 and necessary additives, such as ammonium oxalate and zinc stearate. And the main properties of (U, Gd)O 2 burnable poisonous fuel pellets and the manufacture processes, such as ball-milling blending, granulation, pressing, sintering and grinding are also described. Moreover, the main effect of the process parameters controlled in the manufacture process have been discussed. (authors)

  3. Methods of assembling and disassembling spider and burnable poison rod structures for nuclear reactors

    International Nuclear Information System (INIS)

    Edwards, G.T.; Schluderberg, D.C.

    1981-01-01

    A technique is provided for engaging and disengaging burnable poison rods from a spider in a nuclear reactor fuel assembly. A cap on the end of each of the burnable poison rods is provided with a shank or stem that is received in a respective bore formed in the spider. A frangible flange secures the shank and rod to the spider. Pressing the shank in the direction of the bore axis by means, e.g., of a plate ruptures the frangible flange to release the rod from the spider. (author)

  4. Microstructural evaluation of ceria-samaria-gadolinia-nickel oxide composite after reduction in hydrogen atmosphere

    International Nuclear Information System (INIS)

    Arakaki, A. R.; Yoshito, W.K.; Ussui, V.; Lazar, D.R.R.

    2012-01-01

    The ceria-samaria-gadolinia-nickel composite (Ni-SGDC), used as Solid Oxide Fuel Cell (SOFC) anode, was obtained by 'in situ' reduction of NiO-SGDC, with composition Ce 0,8 (SmGd) 0,2 O 1,9 /NiO and mass proportion 40:60%. The composite was produced by hydroxides coprecipitation using CTAB surfactant, followed by solvothermal treatment in butanol, calcination at 600 deg C, pressing and sintering at 1350 deg C for 1 h. The composite reduction kinetic was evaluated in a tubular furnace under dynamic atmosphere of 4% H2 /Air, fixing the temperature at 900 deg C and time between 10 and 120 minutes. The microstructural characterization was performed by optical and scanning electron microscopy. The samples were characterized either by X-ray diffraction and density measurements by immersion technique in water. It was verified that the NiO reduced fraction reached values between 80 and 90% and the achieved porosity (about 30%) is acceptable to a good anode performance (author)

  5. Neutronic analysis of the JMTR with LEU fuel and burnable poison

    International Nuclear Information System (INIS)

    Nagaoka, Yoshiharu; Oyamada, Rokuro; Matos, J.E.; Woodruff, W.L.

    1985-01-01

    The results of neutronics calculations are presented for the JMTR equilibrium core with LEU silicide fuel, boron and cadmium burnable poisons in the sideplates, and a cycle length of 24 days instead of 11 days with the current HEU fuel. The data indicate that several options are feasible provided that silicide fuels with high uranium densities are successfully demonstrated and licensed (author)

  6. Neutronic analysis of the JMTR with LEU fuel and burnable poison

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Yoshiharu; Oyamada, Rokuro [Japan Atomic Energy Research Institute, Oarai-machi Ibaraki-ken (Japan); Matos, J E; Woodruff, W L [Argonne National Laboratory, Argonne, IL (United States)

    1985-07-01

    The results of neutronics calculations are presented for the JMTR equilibrium core with LEU silicide fuel, boron and cadmium burnable poisons in the sideplates, and a cycle length of 24 days instead of 11 days with the current HEU fuel. The data indicate that several options are feasible provided that silicide fuels with high uranium densities are successfully demonstrated and licensed (author)

  7. Safety aspects of the using Gd as burnable poison in PWR's

    International Nuclear Information System (INIS)

    Vandenberg, C.; Bonet, H.; Charlier, A.

    1978-01-01

    The experience of BELGONUCLEAIRE in using Gd in LWR's has indicated the safety related advantages of this burnable poison. The successfully operation of the BR3 PWR power plant with 5% of Gd rods is presented and extrapolated to large PWR's. (authro)

  8. Effects of limestone petrography and calcite microstructure on OPC clinker raw meals burnability

    Science.gov (United States)

    Galimberti, Matteo; Marinoni, Nicoletta; Della Porta, Giovanna; Marchi, Maurizio; Dapiaggi, Monica

    2017-10-01

    Limestone represents the main raw material for ordinary Portland cement clinker production. In this study eight natural limestones from different geological environments were chosen to prepare raw meals for clinker manufacturing, aiming to define a parameter controlling the burnability. First, limestones were characterized by X-Ray Fluorescence, X-Ray Powder Diffraction and Optical Microscopy to assess their suitability for clinker production and their petrographic features. The average domains size and the microstrain of calcite were also determined by X-Ray Powder Diffraction line profile analysis. Then, each limestone was admixed with clay minerals to achieve the adequate chemical composition for clinker production. Raw meals were thermally threated at seven different temperatures, from 1000 to 1450 °C, to evaluate their behaviour on heating by ex situ X-Ray Powder Diffraction and to observe the final clinker morphology by Scanning Electron Microscopy. Results indicate the calcite microstrain is a reliable parameter to predict the burnability of the raw meals, in terms of calcium silicates growth and lime consumption. In particular, mixtures prepared starting from high-strained calcite exhibit a better burnability. Later, when the melt appears this correlation vanishes; however differences in the early burnability still reflect on the final clinker composition and texture.

  9. Methods of assembling and disassembling spider and burnable poison rod structures for nuclear reactors

    International Nuclear Information System (INIS)

    Walton, L.A.

    1981-01-01

    A method is described of joining burnable poison rods to the spider arms of a pressurised water power reactor fuel assembly which is proof against the reactor core environment but permits these rods to be removed from the spider simply, swiftly and delicately. (U.K.)

  10. Fuel with advanced burnable absorbers design for the IRIS reactor core: Combined Erbia and IFBA

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Fausto [Westinghouse Electric Company LLC, Science and Technology Department, Pittsburgh, PA 15235 (United States)], E-mail: FranceF@westinghouse.com; Petrovic, Bojan [Georgia Institute of Technology, Nuclear and Radiological Engineering, G.W. Woodruff School, Atlanta, GA 30332-0405 (United States)

    2009-08-15

    IRIS is an advanced medium-size (1000 MW) PWR with integral primary system targeting deployment already around 2015-2017. Consistent with its aggressive development and deployment schedule, the 'first IRIS' core design assumes current, licensed fuel technology, i.e., UO{sub 2} fuel with less than 5% {sup 235}U enrichment. The core consists of 89 fuel assemblies employing the 17x17 Westinghouse Robust Fuel Assembly (RFA) design and Standard Fuel dimensions. The adopted design enables to meet all the objectives of the first IRIS core, including over 3-year cycle length with low soluble boron concentration, within the envelope of licensed, readily available fuel technology. Alternative fuel designs are investigated for the subsequent waves of IRIS reactors in pursuit of further improving the fuel utilization and/or extending the cycle length. In particular, an increase in the lattice pitch from the current 0.496 in. for the Standard Fuel to 0.523 in. is among the objectives of this study. The larger fuel pitch and increased moderator-to-fuel volume ratio that it entails fosters better neutron thermalization in an altogether under-moderated lattice thereby offering the potential for considerable increase of fuel utilization and cycle length, up to 5% in the two-batch fuel management scheme considered for IRIS. However, the improved moderation also favors higher values of the Moderator Temperature Coefficient, MTC, which must be properly counteracted to avoid undesired repercussions on the plant safety parameters or controllability during transient operations. This paper investigates counterbalancing the increase in the MTC caused by the enhanced moderation lattice by adopting a suitable choice of fuel burnable absorber (BA). In particular, a fuel design combining erbia, which benefits MTC due to its resonant behavior but leads to residual reactivity penalty, and IFBA, which maximizes cycle length, is pursued. In the proposed approach, IFBA provides the bulk

  11. Anode-supported single-chamber SOFCs based on gadolinia doped ceria electrolytes

    Directory of Open Access Journals (Sweden)

    Morales, M.

    2008-12-01

    Full Text Available The utilization of anode supported electrolytes is a useful strategy to increase the electrical properties of the solid oxide fuel cells, because it is possible to decrease considerably the thickness of the electrolytes. We have prepared successfully singlechamber fuel cells of gadolinia doped ceria electrolytes Ce1-xGdxO2-y (CGO supported on an anode formed by a cermet of Ni-CGO. Mixtures of precursor powders of NiO and gadolinium doped ceria with different particle sizes and compositions were analyzed to obtain optimal bulk porous anodes to be used as anode supported fuel cells. Doped ceria electrolytes were prepared by sol-gel related techniques. Then, ceria based electrolytes were deposited by dip coating at different thickness (15-30 µm using an ink prepared with nanometric powders of electrolytes dispersed in a commercial liquid polymer. Cathodes of La1-xSrxCoO3-s (LSCO were also prepared by sol-gel related techniques and were deposited by dip coating on the electrolyte thick films. Finally, electrical properties were determined in a single-chamber reactor where propane as fuel was mixed with synthetic air above the higher explosive limit. Stable density currents were obtained in these experimental conditions, but flow rates of the carrier gas and propane partial pressure were determinants for the optimization of the electrical properties of the fuel cells.

    La utilización de electrolitos soportados en el ánodo es una estrategia muy útil para mejorar las propiedades eléctricas de las pilas de combustible de óxido sólido, debido a que permiten disminuir considerablemente el espesor de los electrolitos. Para este trabajo, se han preparado exitosamente pilas de combustible de óxido sólido con electrolitos de ceria dopada con Gd, Ce1-xGdxO2-y (CGO soportados sobre un ánodo formado por un cermet de Ni/CGO. Dichas pilas se han

  12. Neutron physical investigations on the use of burnable poisons and gray absorber rods in large pressurized water reactors

    International Nuclear Information System (INIS)

    Brosche, C.; Katinger, T.; Kollmar, W.; Thieme, K.; Wagner, M.R.

    1977-11-01

    Methods and results of neutron physics calculations are described using burnable poisons and gray absorber rods in large PWR's. Calculated and measured values are compared, the effort for programming has been guessed. (orig.) [de

  13. Reloading optimization of pressurized water reactor core with burnable absorber fuel

    International Nuclear Information System (INIS)

    Shi Xiuan; Liu Zhihong; Hu Yongming

    2008-01-01

    The reloading optimization problem of PWR with burnable absorber fuel is very difficult, and common optimization algorithms are inefficient and have bad global performance for it. Characteristic statistic algorithm (CSA) is very fit for the problem. In the past, the reloading optimization using CSA has shortcomings of separating the fuel assemblies' loading pattern (LP) optimization from burnable absorber's placement (BP) optimization. In this study, LP and BP were optimized simultaneously using CSA coupled with CYCLE2D, which is a core analysis code. The corresponding reloading coupling optimization software, CSALPBP, was developed. The 10th cycle reloading design of Daya Bay Nuclear Power Plant was optimized using CSALPBP. The results show that CSALPBP has high efficiency and excellent global performance. (authors)

  14. Obtaining of ceria - samaria - gadolinia ceramics for application as solid oxide fuel cell (SOFC) electrolyte

    International Nuclear Information System (INIS)

    Arakaki, Alexander Rodrigo

    2010-01-01

    Cerium oxide (CeO 2 ) when doped with rare earth oxides has its ionic conductivity enhanced, enabling its use as electrolyte for Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC), which is operated in temperatures between 500 e 700 degree C. The most effective additives or dopants for ionic conductivity improvement are (samarium oxide - Sm 2 O 3 ) and gadolinia (gadolinium oxide - Gd 2 O 3 ), fixing the concentration between 10 and 20 molar%. In this work, Ce 0,8 (SmGd) 0,2 O 1,9 powders have been synthesized by hydroxide, carbonate and oxalate coprecipitation routes. The hydrothermal treatment has been studied for powders precipitated with ammonium hydroxide. A concentrate of rare earths containing 90wt% of CeO 2 and other containing 51% of Sm 2 O 3 and 30% of Gd 2 O 3 , both prepared from monazite processing, were used as starting materials. These concentrates were used due the lower cost compared to pure commercial materials and the chemical similarity of others rare earth elements. Initially, the coprecipitation and calcination conditions were defined. The process efficiency was verified by ceramic sinterability evaluation. The results showed that powders calcined in the range of 450 and 800 degree C presented high specific surface area (90 - 150 m 2 .g -1 ) and fluorite cubic structure, indicating the solid solution formation. It was observed, by scanning electron microscopy, that morphology of particles and agglomerates is a function of precipitant agent. The dilatometric analysis indicated the higher rate of shrinkage at temperatures around 1300-1350 degree C. High densification values (>95% TD) was obtained at temperatures above 1400 degree C. Synthesis by hydroxides coprecipitation followed by hydrothermal treatment demonstrated to be a promising route for crystallization of ceria nano powders at low temperatures (200 degree C). High values of specific surface area were reached with the employment of hydrothermal treatment (about 100 m 2 .g -1

  15. LEU WWR-M2 fuel assemblies burnable test

    International Nuclear Information System (INIS)

    Kirsanov, G.A.; Konoplev, K.A.; Pikulik, R.G.; Sajkov, Yu. P.; Tchmshkyan, D.V.; Tedoradze, L.V.; Zakharov, A.S.

    2000-01-01

    The results of in-pile irradiation tests of LEU WWR-M2 fuel assemblies with reduced enrichment of fuel are submitted in the report. The tests are made according to the Russian Program on Reduced Enrichment for Research and Test Reactors (RERTR). United States Department of Energy and the Ministry of Atomic Energy of Russian Federation jointly fund this Program. The irradiation tests of 5 WWR-M2 experimental assemblies are carried out at WWR-M reactor of the Petersburg Nuclear Physics Institute (PNPI). The information on assembly design and technique of irradiation tests is presented. In the irradiation tests the integrity of fuel assemblies is periodically measured. The report presents the data for the integrity maintained during the burnup of 5 fuel assemblies up to 45%. These results demonstrate the high reliability of the experimental fuel assemblies within the guaranteed burnup limits specified by the manufacturer. The tests are still in progress; it is planned to test and analyze the change in integrity for burnup of up to 70% - 75% or more. LEU WWR-M2 fuel assemblies are to be offered for export by their Novosibirsk manufacturer. Currently, HEU WWR-M2 fuel assemblies are used in Hungary, Ukraine and Vietnam. LEU WWR-M2 fuel assemblies were designed as a possible replacement for the HEU WWR-M2 fuel assemblies in those countries, but their use can be extended to other research reactors. (author)

  16. Incineration of dry burnable waste from reprocessing plants with the Juelich incineration process

    International Nuclear Information System (INIS)

    Dietrich, H.; Gomoll, H.; Lins, H.

    1987-01-01

    The Juelich incineration process is a two stage controlled air incineration process which has been developed for efficient volume reduction of dry burnable waste of various kinds arising at nuclear facilities. It has also been applied to non nuclear industrial and hospital waste incineration and has recently been selected for the new German Fuel Reprocessing Plant under construction in Wackersdorf, Bavaria, in a modified design

  17. Irradiation and corrosion behaviour of cadmium aluminate, a burnable poison for light water reactors

    International Nuclear Information System (INIS)

    Hattenbach, K.; Ahlf, J.; Hilgendorff, W.; Zimmermann, H.U.

    1979-01-01

    In quest of a cadmium containing material for use as burnable poison cadmium aluminate seemed promising. Therefore irradiation and corrosion experiments on specimens of cadmium aluminate in a matrix of aluminia were performed. Irradiation at 575 K and fast fluences up to 10 25 m -2 showed the material to have good radiation resistance and low swelling rates. Cadmium pluminate was resistant to corrosion attack in demineralized water of 575K. (orig.) [de

  18. Neutronic analysis of the JMTR with LEU fuel and burnable poison

    International Nuclear Information System (INIS)

    Nagaoka, Yoshiharu; Oyamada, Rokuro; Matos, J.E.; Woodruff, W.L.

    1984-01-01

    The results of neutronics calculations are presented for the JMTR equilibrium core with LEU silicide fuel, boron and cadmium burnable poisons in the sideplates, and a cycle length of 24 days instead of 11 days with the current HEU fuel. The data indicate that several options are feasible provided that silicide fuels with high uranium densities are successfully demonstrated and licensed. 2 refs., 10 figs., 5 tabs

  19. Rare earths as burnable poison for extended cycles control in electricity generation reactors

    International Nuclear Information System (INIS)

    Asou, M.

    1995-01-01

    The search of an optimization of the French electronuclear network operations leads to a necessary optimization of the core performances. All the economic studies performed by the utilities had shown that there is a real gain to minimize shut down periods for refueling. So, increasing the cycle length from 12 to 18 months will present a gain of shut down for a three years operation period. The theoretical burnable absorber will be a fuel admixed material bringing the required initial negative reactivity with a burn-up kinetic well suited to the fuel and allowing the lowest residual penalty as possible. The residual penalty us defined in this case by the non complete burn up of the poison, by the low of fissile material and by the accumulate of residual isotopes or nuclides. Because of the well known use of gadolinium as burnable absorber for BWR's and PWR's operations, the search for the best compromise to optimize all the above stress is pointed towards the rare earths. In the nuclides family, considering criteria such as cross sections, natural abundance and availability only five nuclides can play the role as burnable absorbers, namely: gadolinium, samarium, dysprosium, europium and erbium. The study presented here will show that only gadolinium and erbium will be considered to control the reactivity of the PWR's. (author). 58 refs., 65 figs., 47 tabs

  20. Optimization of gadolinium burnable poison loading by the conjugate gradients method

    International Nuclear Information System (INIS)

    Drumm, C.R.

    1984-01-01

    Improved use of burnable poison is suggested for pressurized water reactors (PWR's) to insure a sufficiently negative moderator temperature coefficient of reactivity for extended burnup cycles and low leakage refueling patterns. The use of gadolinium as a burnable poison can lead to large axial fluctuations in the power distribution through the cycle. The goal of this work is to determine the optimal axial distribution of gadolinium burnable poison in a PWR to overcome the axial fluctuations, yielding an improved power distribution. The conjugate gradients optimization method is used in this work because of the high degree of nonlinearity of the problem. The neutron diffusion and depletion equations are solved for a one-dimensional one-group core model. The state variables are the flux, the critical soluble boron concentration, and the burnup. The control variables are the number of gadolinium pins per assembly and the beginning-of-cycle gadolinium concentration, which determine the gadolinium cross section. Two separate objectives are considered: 1) to minimize the power peaking factor, which will minimize the capital cost of the plant; and 2) to maximize the cycle length, which will minimize the fuel cost for the plant. It is shown in this work that optimizing the gadolinium distribution can yield an improved power distribution

  1. Effects of sintering atmosphere and initial particle size on sintering of gadolinia-doped ceria; Efeitos da atmosfera de sinterizacao e do tamanho de particula na sinterizacao da ceria-gadolinia

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Rafael Morgado

    2014-07-01

    The effects of the sintering atmosphere and initial particle size on the sintering of ceria containing 10 mol% gadolinia (GdO{sub 1.5}) were systematically investigated. The main physical parameter was the specific surface area of the initial powders. Nanometric powders with three different specific surface areas were utilized, 210 m{sup 2}/g, 36,2 m{sup 2}/g e 7,4 m{sup 2}/g. The influence on the densification, and micro structural evolution were evaluated. The starting sintering temperature was verified to decrease with increasing on the specific surface area of raw powders. The densification was accelerated for the materials with smaller particle size. Sintering paths for crystallite growth were obtained. Master sintering curves for gadolinium-doped ceria were constructed for all initial powders. A computational program was developed for this purpose. The results for apparent activation energy showed noticeable dependence with specific surface area. In this work, the apparent activation energy for densification increased with the initial particle size of powders. The evolution of the particle size distributions on non isothermal sintering was investigated by WPPM method. It was verified that the grain growth controlling mechanism on gadolinia doped ceria is the pore drag for initial stage and beginning of intermediate stage. The effects of the sintering atmosphere on the stoichiometry deviation of ceria, densification, microstructure evolution, and electrical conductivity were analyzed. Inert, oxidizing, and reducing atmospheres were utilized on this work. Deviations on ceria stoichiometry were verified on the bulk materials. The deviation verified was dependent of the specific surface area and sintering atmosphere. Higher reduction potential atmospheres increase Ce{sup 3+} bulk concentration after sintering. Accelerated grain growth and lower electrical conductivities were verified when reduction reactions are significantly present on sintering. (author)

  2. Heat capacity of Dy6UO12(s)

    International Nuclear Information System (INIS)

    Sahu, M.; Nagara, B.K.; Saxena, M.K.; Dash, S.

    2010-01-01

    There is a need to improve the reactor performance through longer cycle length, which is being carried out by initial fuel enrichment. This additional fuel enrichment is being compensated by introduction of additional neutron absorber material called as burnable poison. Burnable poisons are materials having one or more isotopes which have high neutron absorption cross section and gets converted into other isotopes of relatively low absorption cross section. The use of burnable poison provides the necessary negative moderator reactivity coefficient at the beginning of core life and helps shape core power distribution. Usually rare-earth elements such as gadolinium, dysprosium and samarium have been applied for this purpose. Presently gadolinia doped urania is being used as burnable poison in boiling water reactor (BWR)

  3. Synthesis and characterization of gadolinia-doped ceria-silver cermet cathode material for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Datta, Pradyot; Majewski, Peter; Aldinger, Fritz

    2008-01-01

    A series of Ce 0.9 Gd 0.1 O 2-δ -Ag cermets with different Ag contents were prepared by conventional sintering process aiming at assessing the suitability of using them as cathode material for solid oxide fuel cell (SOFC) with Gadolinia-doped ceria electrolyte. The chemical compatibility between Ce 0.9 Gd 0.1 O 2-δ (CGO) and Ag was investigated by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Thermal expansion coefficients of the cermets were measured as a function of Ag content and were found to increase with metallic content. Although oxygen adsorption at the surface of the cermets could be detected, no reaction or solid solubility between CGO and Ag was found

  4. Volume Reduction of Decommissioning Radioactive Burnable and Metal Wastes

    Energy Technology Data Exchange (ETDEWEB)

    Min, B. Y.; Lee, Y. J.; Yun, G. S.; Lee, K. W.; Moon, J. K. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, Y. K.; Cho, J. H. [SunKwang Atomic Energy Safety Co., Seoul (Korea, Republic of)

    2014-10-15

    A large quantity of radioactive waste was generated during the decommissioning projects. For the purpose of the volume reduction and clearance for decommissioning wastes from decommissioning projects, the incineration and high melting technology has been selected for the decommissioning wastes treatment. The volume reduction of the combustible wastes through the incineration technologies has merits from the view point of a decrease in the amount of waste to be disposed of resulting in a reduction of the disposal cost. Incineration is generally accepted as a method of reducing the volume of radioactive waste. The incineration technology is an effective treatment method that contains hazardous chemicals as well as radioactive contamination. Incinerator burns waste at high temperature. Incineration of a mixture of chemically hazardous and radioactive materials, known as 'mixed waste,' has two principal goals: to reduce the volume and total chemical toxicity of the waste. Incineration itself does not destroy the metals or reduce the radioactivity of the waste. A proven melting technology is currently used for low-level waste (LLW) at several facilities worldwide. These facilities use melting as a means of processing LLW for unrestricted release of the metal or for recycling within the nuclear sector. About 16.4 tons of decommissioning combustible waste has been treated using Oxygen Enriched incineration. The incineration facility operated quite smoothly through the analysis major critical parameters of off-gas.

  5. Volume Reduction of Decommissioning Radioactive Burnable and Metal Wastes

    International Nuclear Information System (INIS)

    Min, B. Y.; Lee, Y. J.; Yun, G. S.; Lee, K. W.; Moon, J. K.; Choi, Y. K.; Cho, J. H.

    2014-01-01

    A large quantity of radioactive waste was generated during the decommissioning projects. For the purpose of the volume reduction and clearance for decommissioning wastes from decommissioning projects, the incineration and high melting technology has been selected for the decommissioning wastes treatment. The volume reduction of the combustible wastes through the incineration technologies has merits from the view point of a decrease in the amount of waste to be disposed of resulting in a reduction of the disposal cost. Incineration is generally accepted as a method of reducing the volume of radioactive waste. The incineration technology is an effective treatment method that contains hazardous chemicals as well as radioactive contamination. Incinerator burns waste at high temperature. Incineration of a mixture of chemically hazardous and radioactive materials, known as 'mixed waste,' has two principal goals: to reduce the volume and total chemical toxicity of the waste. Incineration itself does not destroy the metals or reduce the radioactivity of the waste. A proven melting technology is currently used for low-level waste (LLW) at several facilities worldwide. These facilities use melting as a means of processing LLW for unrestricted release of the metal or for recycling within the nuclear sector. About 16.4 tons of decommissioning combustible waste has been treated using Oxygen Enriched incineration. The incineration facility operated quite smoothly through the analysis major critical parameters of off-gas

  6. Uranium enrichment. Enrichment processes

    International Nuclear Information System (INIS)

    Alexandre, M.; Quaegebeur, J.P.

    2009-01-01

    Despite the remarkable progresses made in the diversity and the efficiency of the different uranium enrichment processes, only two industrial processes remain today which satisfy all of enriched uranium needs: the gaseous diffusion and the centrifugation. This article describes both processes and some others still at the demonstration or at the laboratory stage of development: 1 - general considerations; 2 - gaseous diffusion: physical principles, implementation, utilisation in the world; 3 - centrifugation: principles, elementary separation factor, flows inside a centrifuge, modeling of separation efficiencies, mechanical design, types of industrial centrifuges, realisation of cascades, main characteristics of the centrifugation process; 4 - aerodynamic processes: vortex process, nozzle process; 5 - chemical exchange separation processes: Japanese ASAHI process, French CHEMEX process; 6 - laser-based processes: SILVA process, SILMO process; 7 - electromagnetic and ionic processes: mass spectrometer and calutron, ion cyclotron resonance, rotating plasmas; 8 - thermal diffusion; 9 - conclusion. (J.S.)

  7. Study of the Effect of Burnable Poison Particles Applying in a Pebble Bed HTR

    International Nuclear Information System (INIS)

    Wei Chunlin; Zhao Jing; Zhang Jian; Xia Bing

    2014-01-01

    In pebble bed high temperature gas cooled reactors (HTR), spherical fuel elements pass through the core several times to balance the burnup process in the fuel region, resulting in an acceptable shape and peak factor of power density in the simulation analysis. In contrast, when fuel elements pass through the core only once, the peak of power density occurs at the top of the core and its value is too high to be safe. These indicators/parameters can be improved by incorporating burnable poison in the fuel elements under certain conditions. In the current study, burnable poison particles (BPPs) in fuel elements are evaluated. In spite of the strong absorption capability of "1"0B, BPPs can decrease the depletion speed and increase the duration of "1"0B because of the self-shielding effect, resulting in improved shape and peak factor of power distribution. Several BPPs with different radius are discussed in power distribution, following the calculation for a full-scale reactor core with modified VSOP code. According the result, applying BPPs on fuel pebbles is an effective means to improve the distribution of the power density under one-through fuel load in HTR. (author)

  8. Experimental and theoretical burnup investigations on model arrangements with solid burnable poisons

    International Nuclear Information System (INIS)

    Ahlf, J.; Anders, D.; Greim, L.; Knoth, J.; Kolb, M.; Mittelstaedt, B.; Mueller, A.; Schwenke, H.

    1975-01-01

    It is the scope of the two experiments here to improve the methods for computation and measurement as well as the experimental technique appropriate to predict the burnable poison rod burn-up with sufficient accuracy. In the first experiment two nine-rod bundles in a 3 x 3 arrangement are irradiated during several irradiation periods in the research reactor Geesthacht. Each bundle consists of eight outer rods containing fuel and one inner rod containing poison (B 10 or Cd 113). The burn-up of the fuel and the burnable poison is measured by non-destructive methods after each irradiation period and then compared with results of a burn-up calculation. In the second experiment two poison rods with different cadmium concentrations and one rod containing boron are irradiated during several irradiation periods in the research reactor Geesthacht. The burn-up is determined after each irradiation period by reactivity measurements and its result compared to computed effective absorption cross-sections of the rods by aid of a calibration curve. For both experiments the experimental and theoretical results for the poison burn-up are found to be within the error limits of the measurements. (orig.) [de

  9. Experimental and theoretical investigations on solid burnable poison burnup of model arrangements

    International Nuclear Information System (INIS)

    Ahlf, J.; Anders, D.; Greim, L.; Knoth, J.; Kolb, M.; Mittelstaedt, B.; Mueller, A.; Schwenke, H.

    1975-01-01

    It is the scope of the two experiments reported here to improve the methods for computation and measurement as well as the experimental technique appropriate to predict the burnable poison rod burn-up with sufficient accuracy. In the first experiment two nine-rod bundles in a 3 x 3 arrangement are irradiated during several irradiation periods in the research reactor Geesthacht. Each bundle consists of eight outer rods containing fuel and one inner rod containing poison (B 10 or Cd 113). The burn-up of the fuel and the burnable poison is measured by non-destructive methods after each irradiation period and then compared with results of a burn-up calculation. In the second experiment two poison rods with different cadmium concentrations and one rod containing boron are irradiated during several irradiation periods in the research reactor Geesthacht. The burn-up is determined after each irradiation period by reactivity measurements and its result compared to computed effective absorption cross-sections of the rods by aid of a calibration curve. For both experiments the experimental and theoretical results for the poison burn-up are found to be within the error limits of the measurements. (orig.) [de

  10. Singler-chamber SOFCs based on gadolinia doped ceria operated on methane and propane; Pilas de combustible de una sola camara, basadas en electrolitos de ceria dopada con gadolinia y operadas con metano y propano

    Energy Technology Data Exchange (ETDEWEB)

    Morales, M.; Roa, J. J.; Capdevila, X. G.; Segarra, M.; Pinol, S.

    2010-07-01

    The main advantages of single-chamber solid oxide fuel cells (SOFCs) respect to dual-chamber SOFCs, are to simplify the device design and to operate in mixtures of hydrocarbon (methane, propane...) and air, with no separation between fuel and oxidant. However, this design requires the use of selective electrodes for the fuel oxidation and the oxidant reduction. In this work, electrolyte-supported SOFCs were fabricated using gadolinia doped ceria (GDC) as the electrolyte, Ni + GDC as the anode and LSC(La{sub 0}.5Sr{sub 0}.5CoO{sub 3}-{delta})-GDC-Ag{sub 2}O as the cathode. The electrical properties of the cell were determined in mixtures of methane + air and propane + air. The influence of temperature, gas composition and total flow rate on the fuel cell performance was investigated. As a result, the power density was strongly increased with increasing temperature, total flow rate and hydrocarbon composition. Under optimized gas compositions and total flow conditions, power densities of 70 and 320 mW/cm{sup 2} operating on propane at a temperature of 600 degree centigrade and methane (795 degree centigrade) were obtained, respectively. (Author)

  11. The effect of CTAB on synthesis in butanol of samaria and gadolinia doped ceria - nickel oxide ceramics

    International Nuclear Information System (INIS)

    Arakaki, A.R.; Cunha, S.M.; Yoshito, W.K.; Ussui, V.; Lazar, D.R.R.

    2011-01-01

    In this work it was synthesized doped ceria and Samaria gadolinia - nickel oxide ceramics, mainly applied as anodes Fuel Cells Solid Oxide. Powders of composition Ce 0,8 (SmGd) 0,2 O 1,9 /NiO and mass ratio of 40: 60% were initially synthesized by hydroxides coprecipitation and then treated solvo thermically in butanol. Cerium samarium, gadolinium and nickel chlorides and CTAB with molar ratio metal / CTAB ranging from 1 to 3, were used as raw materials Powders were treated in butanol at 150 deg C for 16h. The powders were analyzed by X-ray diffraction, scanning electron microscopy, specific surface area for adsorption of nitrogen and particle size distribution by laser beam scattering. The ceramics were analyzed by scanning electron microscopy and density measurements by immersion technique in water. The results showed that the powders had the characteristic crystalline structures of ceria and nickel hydroxide, and high specific surface area (80 m 2 / g). The characterizations of ceramics demonstrated high chemical homogeneity and porosity values of 30%. (author)

  12. Solid oxide fuel cell bi-layer anode with gadolinia-doped ceria for utilization of solid carbon fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kellogg, Isaiah D. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 290A Toomey Hall, 400 West 13th Street, Rolla, MO 65409 (United States); Department of Materials Science and Engineering, Missouri University of Science and Technology, 223 McNutt Hall, 1400 N. Bishop, Rolla, MO 65409 (United States); Koylu, Umit O. [Department of Mechanical and Aerospace Engineering, Missouri University of Science and Technology, 290A Toomey Hall, 400 West 13th Street, Rolla, MO 65409 (United States); Dogan, Fatih [Department of Materials Science and Engineering, Missouri University of Science and Technology, 223 McNutt Hall, 1400 N. Bishop, Rolla, MO 65409 (United States)

    2010-11-01

    Pyrolytic carbon was used as fuel in a solid oxide fuel cell (SOFC) with a yttria-stabilized zirconia (YSZ) electrolyte and a bi-layer anode composed of nickel oxide gadolinia-doped ceria (NiO-GDC) and NiO-YSZ. The common problems of bulk shrinkage and emergent porosity in the YSZ layer adjacent to the GDC/YSZ interface were avoided by using an interlayer of porous NiO-YSZ as a buffer anode layer between the electrolyte and the NiO-GDC primary anode. Cells were fabricated from commercially available component powders so that unconventional production methods suggested in the literature were avoided, that is, the necessity of glycine-nitrate combustion synthesis, specialty multicomponent oxide powders, sputtering, or chemical vapor deposition. The easily-fabricated cell was successfully utilized with hydrogen and propane fuels as well as carbon deposited on the anode during the cyclic operation with the propane. A cell of similar construction could be used in the exhaust stream of a diesel engine to capture and utilize soot for secondary power generation and decreased particulate pollution without the need for filter regeneration. (author)

  13. Burnable poison calculations for Mk.III gas-cooled reactor systems

    Energy Technology Data Exchange (ETDEWEB)

    Gubbins, M E

    1971-02-15

    A method of calculating the reactivity and burn-up hisotry of a Mk.III GCR system containing burnable poisons has been described. The method allows for poison-fuel interaction. Using the method it has been shown that burn-up of the poison under a constant incident flux can give errors of the order of 1-2 niles. A calculation using the method described will take about 50% longer than a straightforward fuel burn-up calculation in the same number of groups. The multi-cell approach has a potential for handling greater geometrical complexity. It is intended to compare the method against experiment as soon as suitable experimental results become available.

  14. Transient performance and design aspects of low boron PWR cores with increased utilization of burnable absorbers

    International Nuclear Information System (INIS)

    Papukchiev, Angel; Schaefer, Anselm

    2008-01-01

    In conventional pressurized water reactor (PWR) designs, soluble boron is used for reactivity control over core fuel cycle. As high boron concentrations have significant impact on reactivity feedback properties and core transient behaviour, design changes to reduce boron concentration in the reactor coolant are of general interest in view of improving PWR inherent safety. In order to assess the potential advantages of such strategies in current PWRs, two low boron core configurations based on fuel with increased utilization of gadolinium and erbium burnable absorbers have been developed. The new PWR designs permit to reduce the natural boron concentration in reactor coolant at begin of cycle to 518 (Gd) and 805 (Er) ppm. An innovative low boron core design methodology was implemented combining a simplified reactivity balance search procedure with a core design approach based on detailed 3D diffusion calculations. Fuel cross sections needed for nuclear libraries were generated using the 2D lattice code HELIOS [2] and full core configurations were modelled with the 3D diffusion code QUABOX/CUBBOX [3]. For dynamic 3D calculations, the coupled code system ATHLET - QUABOX/CUBBOX was used [4]. The new cores meet German acceptance criteria regarding stuck rod, departure from nucleate boiling ratio (DNBR), shutdown margin, and maximal linear power. For the assessment of potential safety advantages of the new cores, comparative analyses were performed for three PWR core designs: the already mentioned two low boron designs and a standard design. The improved safety performance of the low boron cores in anticipated transients without scram (ATWS), boron dilution scenarios and beyond design basis accidents (BDBA) has already been reported in [1, 2 and 3]. This paper gives a short reminder on the results obtained. Moreover, it deals not only with the potential advantages, but also addresses the drawbacks of the new PWR configurations - complex core design, increased power

  15. Nuclear criticality safety: general. 5. Reactivity Effect of Burnable Absorbers in Burnup Credit for the CASTOR X/32S Storage and Transport Cask

    International Nuclear Information System (INIS)

    Rombough, Charles T.; Lancaster, Dale B.; Diersch, Rudolf; Spilker, Harry

    2001-01-01

    When considering burnup credit in the licensing of storage and transportation casks, a significant effect is whether or not the burned fuel was depleted with burnable absorbers present. This paper presents the results of detailed calculations to quantitatively determine the burnable absorber effect for the CASTOR X/32S transport cask, which assumes burnup of the fuel in the criticality analysis. A radial view of the CASTOR X/32S cask is shown in Fig. 1. This is the actual plot of the geometry as modeled in KENO V.a. Note that there are no water-filled flux traps and the assemblies are tightly packed. This reduces the overall dimensions of the cask for a given number of fuel assemblies. Reactivity is held down by borated aluminum plates between the fuel assemblies and by placing absorber rod modules (ARMs) in the guide tubes of selected assemblies. If burnup of the fuel is not considered and the initial enrichment is 5.0 wt% 235 U, then 28 of the 32 fuel assemblies must contain an ARM to maintain a k eff 3 ; 4. moderator temperature of 604 K; 5. cooling time of 9.5 yr; 6. specific power of 60 W/g of U metal; 7. conservative axial and radial burnup shape distribution; 8. Westinghouse BP material containing 12.5 wt% B 4 C. Using the model described earlier, calculations were performed with varying numbers of BP fingers inserted for different exposure times. The results are shown in Tables I and II. The 1 s statistical error in these results is σ equals ±0.05%. Note that the BP finger and exposure effects decrease with fuel burnup and the effect is smaller when the cask contains ARMs. Conservatively combining the results from Tables I and II and interpolating, we can equate fewer BP fingers with longer BP exposure time as shown in Table III. The Table III results were checked by running the actual cases (for example, 20 BP fingers for 24 GWd/tonne exposure) to verify that the k eff 's for the cask were always less than the base-case values. These results can also be

  16. Isotope enrichment

    International Nuclear Information System (INIS)

    Lydtin, H-J.; Wilden, R.J.; Severin, P.J.W.

    1978-01-01

    The isotope enrichment method described is based on the recognition that, owing to mass diffusion and thermal diffusion in the conversion of substances at a heated substrate while depositing an element or compound onto the substrate, enrichment of the element, or a compound of the element, with a lighter isotope will occur. The cycle is repeated for as many times as is necessary to obtain the degree of enrichment required

  17. Uranium enrichment

    International Nuclear Information System (INIS)

    1990-01-01

    This report looks at the following issues: How much Soviet uranium ore and enriched uranium are imported into the United States and what is the extent to which utilities flag swap to disguise these purchases? What are the U.S.S.R.'s enriched uranium trading practices? To what extent are utilities required to return used fuel to the Soviet Union as part of the enriched uranium sales agreement? Why have U.S. utilities ended their contracts to buy enrichment services from DOE?

  18. Reactivity determination of the Al2O3-B4C burnable poison as a function of its concentration in the IPEN/MB-01 reactor

    International Nuclear Information System (INIS)

    Giada, Marino Reis

    2005-01-01

    Burnable poison rods made of Al 2 O 3 -B 4 C pellets with different concentrations of 10 B have been manufactured for a set of experiments in the IPEN/MB-01 zero-power reactor. The experiments evaluated the reactivity of the burnable poison rods as a function of the 10 B concentration, and the shadowing effect on the control rod reactivity worth as a function of the distance between the burnable position rods and the control rod. The results showed that the burnable poison rods have a non-linear behavior as function of the 10 B concentration, starting to reach an asymptotic value for concentrations higher than 7 g/cm 3 of 10 B. The shadowing effect on the control rods was substantial. When the burnable poison rods were beside the control rod, its reactivity worth decreased as much as 30 %, and when they were 10,5 cm distant, the control rod worth decreased by 7 %. The MCNP results for the burnable poison reactivity effects agreed within experimental errors with the measured values. (author)

  19. Assessment of erbium as candidate burnable absorber for future PWR operaning cycles: A neutronic and fabrication study

    International Nuclear Information System (INIS)

    Asou, M.; Dehaudt, P.; Porta, J.

    1995-01-01

    Erbium begins to play a role in the control of PWR core reactivity. Generally speaking, burnable absorbers were only used to establish fresh core equilibrium. In France, since the possibility of extending irradiation cycles by 12 to 18 months, then up to 24 and 30 months, has been envisaged, there is renewed interest in burnable absorbers. The fabrication of PWR pellets has been investigated, providing high density and a good erbium homogeneity. The pellets characteristics were consistent with the specifications of PWR fuel. However, with the present process, the grain size remains small. Studies in progress now shows that erbium is not only a valuable alternative to gadolinium, for long fuel cycles (≥18 months) but also a new fuel concept. (orig.)

  20. New long-cycle small modular PWR cores using particle type burnable poisons for low boron operation

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Hoseong; Hwang, Dae Hee [Department of Nuclear Engineering, Kyung Hee University, Deogyeong-daero, GiHeung-gu, Yongin, Gyeonggi-do 446-701 (Korea, Republic of); Hong, Ser Gi, E-mail: sergihong@khu.ac.kr [Department of Nuclear Engineering, Kyung Hee University, Deogyeong-daero, GiHeung-gu, Yongin, Gyeonggi-do 446-701 (Korea, Republic of); Shin, Ho Choel [Core and Fuel Analysis Group, Korea Hydro & Nuclear Power Central Research Institute (KHNP-CRI), Daejon 305-343 (Korea, Republic of)

    2017-04-01

    Highlights: • New advanced burnable poison rods (BPR) are suggested for low boron operation in PWR. • The new SMR cores have long cycle length of ∼4.5 EFPYs with low boron concentration. • The SMR core satisfies all the design targets and constraints. - Abstract: In this paper, new small long-cycle PWR (Pressurized Water Reactor) cores for low boron concentration operation are designed by employing advanced burnable poison rods (BPRs) in which the BISO (Bi-Isotropic) particles of burnable poison are distributed in a SiC matrix. The BPRs are designed by adjusting the kernel diameter, the kernel material and the packing fraction to effectively reduce the excess reactivity in order to reduce the boron concentration in the coolant and achieve a flat change in excess reactivity over a long operational cycle. In addition, axial zoning of the BPRs was suggested to improve the core performances, and it was shown that the suggested axial zoning of BPRs considerably extends the cycle length compared to a core with no BPR axial zoning. The results of the core physics analyses showed that the cores using BPRs with a B{sub 4}C kernel have long cycle lengths of ∼4.5 EFPYs (Effective Full Power Years), small maximum CBCs (Critical Boron Concentration) lower than 370 ppm, low power peaking factors, and large shutdown margins of control element assemblies.

  1. Uranium enrichment

    International Nuclear Information System (INIS)

    1989-01-01

    GAO was asked to address several questions concerning a number of proposed uranium enrichment bills introduced during the 100th Congress. The bill would have restructured the Department of Energy's uranium enrichment program as a government corporation to allow it to compete more effectively in the domestic and international markets. Some of GAO's findings discussed are: uranium market experts believe and existing market models show that the proposed DOE purchase of a $750 million of uranium from domestic producers may not significantly increase production because of large producer-held inventories; excess uranium enrichment production capacity exists throughout the world; therefore, foreign producers are expected to compete heavily in the United States throughout the 1990s as utilities' contracts with DOE expire; and according to a 1988 agreement between DOE's Offices of Nuclear Energy and Defense Programs, enrichment decommissioning costs, estimated to total $3.6 billion for planning purposes, will be shared by the commercial enrichment program and the government

  2. Uranium enrichment

    International Nuclear Information System (INIS)

    Rae, H.K.; Melvin, J.G.

    1988-06-01

    Canada is the world's largest producer and exporter of uranium, most of which is enriched elsewhere for use as fuel in LWRs. The feasibility of a Canadian uranium-enrichment enterprise is therefore a perennial question. Recent developments in uranium-enrichment technology, and their likely impacts on separative work supply and demand, suggest an opportunity window for Canadian entry into this international market. The Canadian opportunity results from three particular impacts of the new technologies: 1) the bulk of the world's uranium-enrichment capacity is in gaseous diffusion plants which, because of their large requirements for electricity (more than 2000 kW·h per SWU), are vulnerable to competition from the new processes; 2) the decline in enrichment costs increases the economic incentive for the use of slightly-enriched uranium (SEU) fuel in CANDU reactors, thus creating a potential Canadian market; and 3) the new processes allow economic operation on a much smaller scale, which drastically reduces the investment required for market entry and is comparable with the potential Canadian SEU requirement. The opportunity is not open-ended. By the end of the century the enrichment supply industry will have adapted to the new processes and long-term customer/supplier relationships will have been established. In order to seize the opportunity, Canada must become a credible supplier during this century

  3. Uranium enrichment

    International Nuclear Information System (INIS)

    Mohrhauer, H.

    1982-01-01

    The separation of uranium isotopes in order to enrich the fuel for light water reactors with the light isotope U-235 is an important part of the nuclear fuel cycle. After the basic principals of isotope separation the gaseous diffusion and the centrifuge process are explained. Both these techniques are employed on an industrial scale. In addition a short review is given on other enrichment techniques which have been demonstrated at least on a laboratory scale. After some remarks on the present situation on the enrichment market the progress in the development and the industrial exploitation of the gas centrifuge process by the trinational Urenco-Centec organisation is presented. (orig.)

  4. Optimization method of rod-type burnable poisons for nuclear designs of HTGRs

    International Nuclear Information System (INIS)

    Yamashita, Kiyonobu

    1994-01-01

    In block-type HTGRs, control rod insertion depths into cores had to be maintained as small as possible at full power operations, to avoid a fuel temperature rise. Thus, specifications (poison atom density (N BP ) and radius (r)) of rod-type burnable poisons (BPs) had to be optimized so that the effective multiplication factor (k eff ) would be constant at a minimum value throughout a planned burnup period. However, the optimization had been a time-consuming work until now since survey calculations had to be done for most possible combinations of N BP and r. To solve this problem, I have found a optimization method consisting of two steps. In the first step, approximation formulas describing a time-dependent relation among effective absorption cross sections (Σ aBP ), N BP and r are used to select promising combinations of N BP and r beforehand. In the second step, the best combination of N BP and r is determined by a comparison between Σ aBP of each promising combination and expected one. The number of survey calculations was reduced to about 1/10 by the optimization method. The change in k eff for 600 burnup days was reduced to 2%Δk by the method. Hence, it was made possible to operate reactors practically without inserting the control rods into cores. (author)

  5. Study of burnable poisons and gadolinium qualification in light water reactors

    International Nuclear Information System (INIS)

    Nasr, Mohamed.

    1981-09-01

    The aim of this work is to develop a calculation procedure for analyzing light water moderated reactors utilizing gadolinium as a burnable poison. The main points of this work can be summarized as follows: the available cross section data of gadolinium were analysed and corrected whenever it was necessary. The processes which include required precautions for obtaining multigroup cross sections were defined; an exhaustive study of the assumptions used in multicell calculation methods allowed the definition of option to be used for obtaining good results without excessive calculation cost. This study was followed by the interpretation of experimental results; when gadolinium is used in grain structure, a problem of double heterogeneity is encountered. A new calculation method was developed for such situations. Its validity was confirmed by a comparison with the Monte Carlo method; the problems encountered in performing a study of burn up of fuel elements containing gadolinium were analysed and the necessary precautions were established. The effect of the initial charge and geometrical form of the gadolinium and the behavior of lattices during the burn up were examined [fr

  6. Effect of Ca and Li additions on densification and electrical conductivity of 10 mol% gadolinia-doped ceria prepared by the coprecipitation technique; Efeito de adicoes de litio e calcio na densificacao e na condutividade eletrica da ceria-10% mol gadolinia preparada pela tecnica de co-precipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Porfirio, T.C.

    2010-07-01

    Ceria containing rare-earth ceramics are potential candidates for application in intermediate-temperature solid oxide fuel cells. One of the main problems related to these ceramic materials is their relatively low sinterability. In this work, the effects of Ca and Li additions on densification and electrical conductivity of 10 mol% gadolinia-doped ceria was investigated. Ceramic compositions containing 1.5 mol% Ca or Li were prepared by the oxalate coprecipitation technique. Results of sintered density and electrical conductivity were compared to those of ceramic samples obtained by solid state reactions showing the effects of the synthesis method on densification and total electrical conductivity of the sintered materials. (author)

  7. Fuel assembly and reactor core

    International Nuclear Information System (INIS)

    Aoyama, Motoo; Koyama, Jun-ichi; Uchikawa, Sadao; Bessho, Yasunori; Nakajima, Akiyoshi; Maruyama, Hiromi; Ozawa, Michihiro; Nakamura, Mitsuya.

    1990-01-01

    The present invention concerns fuel assemblies charged in a BWR type reactor and the reactor core. The fuel assembly comprises fuel rods containing burnable poisons and fuel rods not containing burnable poisons. Both of the highest and the lowest gadolinia concentrations of the fuel rods containing gadolinia as burnable poisons are present in the lower region of the fuel assembly. This can increase the spectral shift effect without increasing the maximum linear power density. (I.N.)

  8. Multi level optimization of burnable poison utilization for advanced PWR fuel management

    Science.gov (United States)

    Yilmaz, Serkan

    The objective of this study was to develop an unique methodology and a practical tool for designing burnable poison (BP) pattern for a given PWR core. Two techniques were studied in developing this tool. First, the deterministic technique called Modified Power Shape Forced Diffusion (MPSFD) method followed by a fine tuning algorithm, based on some heuristic rules, was developed to achieve this goal. Second, an efficient and a practical genetic algorithm (GA) tool was developed and applied successfully to Burnable Poisons (BPs) placement optimization problem for a reference Three Mile Island-1 (TMI-1) core. This thesis presents the step by step progress in developing such a tool. The developed deterministic method appeared to perform as expected. The GA technique produced excellent BP designs. It was discovered that the Beginning of Cycle (BOC) Kinf of a BP fuel assembly (FA) design is a good filter to eliminate invalid BP designs created during the optimization process. By eliminating all BP designs having BOC Kinf above a set limit, the computational time was greatly reduced since the evaluation process with reactor physics calculations for an invalid solution is canceled. Moreover, the GA was applied to develop the BP loading pattern to minimize the total Gadolinium (Gd) amount in the core together with the residual binding at End-of-Cycle (EOC) and to keep the maximum peak pin power during core depletion and Soluble boron concentration at BOC both less than their limit values. The number of UO2/Gd2O3 pins and Gd 2O3 concentrations for each fresh fuel location in the core are the decision variables and the total amount of the Gd in the core and maximum peak pin power during core depletion are in the fitness functions. The use of different fitness function definition and forcing the solution movement towards to desired region in the solution space accelerated the GA runs. Special emphasize is given to minimizing the residual binding to increase core lifetime as

  9. New Small LWR Core Designs using Particle Burnable Poisons for Low Boron Concentration

    International Nuclear Information System (INIS)

    Yoo, Ho Seong; Hwang, Dae Hee; Hong, Ser Gi

    2015-01-01

    The soluble boron has two major important roles in commercial PWR operations : 1) the control of the long-term reactivity to maintain criticality under normal operation, and 2) the shutdown of the reactor under accidents. However, the removal of the soluble boron gives several advantages in SMRs (Small Modular Reactor). These advantages resulted from the elimination of soluble boron include the significant simplification of nuclear power plant through the removal of pipes, pumps, and purification systems. Also, the use of soluble boron mitigates corrosion problems on the primary coolant loop. Furthermore, the soluble boron-free operation can remove an inadvertent boron dilution accident (BDA) which can lead to a significant insertion of positive reactivity. From the viewpoint of core physics, the removal of soluble boron or reduction of soluble boron concentration makes the moderator temperature coefficient (MTC) more negative. From the core design studies using new fuel assemblies, it is shown that the cores have very low critical soluble boron concentrations less than 500ppm, low peaking factors within the design targets, strong negative MTCs over cycles, and large enough shutdown margins both at BOC and EOC. However, the present cores have relatively low average discharge burnups of ∼ 30MWD/kg leading to low fuel economy because the cores use lots of non-fuel burnable poison rods to achieve very low critical boron concentrations. So, in the future, we will perform the trade-off study between the fuel discharge burnup and the boron concentrations by changing fuel assembly design and the core loading pattern

  10. New Small LWR Core Designs using Particle Burnable Poisons for Low Boron Concentration

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Ho Seong; Hwang, Dae Hee; Hong, Ser Gi [Kyung Hee University, Yongin (Korea, Republic of)

    2015-05-15

    The soluble boron has two major important roles in commercial PWR operations : 1) the control of the long-term reactivity to maintain criticality under normal operation, and 2) the shutdown of the reactor under accidents. However, the removal of the soluble boron gives several advantages in SMRs (Small Modular Reactor). These advantages resulted from the elimination of soluble boron include the significant simplification of nuclear power plant through the removal of pipes, pumps, and purification systems. Also, the use of soluble boron mitigates corrosion problems on the primary coolant loop. Furthermore, the soluble boron-free operation can remove an inadvertent boron dilution accident (BDA) which can lead to a significant insertion of positive reactivity. From the viewpoint of core physics, the removal of soluble boron or reduction of soluble boron concentration makes the moderator temperature coefficient (MTC) more negative. From the core design studies using new fuel assemblies, it is shown that the cores have very low critical soluble boron concentrations less than 500ppm, low peaking factors within the design targets, strong negative MTCs over cycles, and large enough shutdown margins both at BOC and EOC. However, the present cores have relatively low average discharge burnups of ∼ 30MWD/kg leading to low fuel economy because the cores use lots of non-fuel burnable poison rods to achieve very low critical boron concentrations. So, in the future, we will perform the trade-off study between the fuel discharge burnup and the boron concentrations by changing fuel assembly design and the core loading pattern.

  11. Isotope enrichment

    International Nuclear Information System (INIS)

    Garbuny, M.

    1979-01-01

    The invention discloses a method for deriving, from a starting material including an element having a plurality of isotopes, derived material enriched in one isotope of the element. The starting material is deposited on a substrate at less than a critical submonatomic surface density, typically less than 10 16 atoms per square centimeter. The deposit is then selectively irradiated by a laser (maser or electronic oscillator) beam with monochromatic coherent radiation resonant with the one isotope causing the material including the one istope to escape from the substrate. The escaping enriched material is then collected. Where the element has two isotopes, one of which is to be collected, the deposit may be irradiated with radiation resonant with the other isotope and the residual material enriched in the one isotope may be evaporated from the substrate and collected

  12. Calculational modeling of fuel assemblies of WWER-1000 type with the use of burnable absorber Gadolinum; comparative analysis

    International Nuclear Information System (INIS)

    Yeremenko, M.L.; Kovbasenko, Yu.P.; Loetsch, T.

    2001-01-01

    In connection with the beginning of the use of fuel assemblies with burnable absorbers by integration of Gadolinum into the nuclear fuel at Ukrainian NPP the task of testing the code systems and the pertinent neutron cross section libraries for the new fuel arose. Taking into account the long term experience of German experts with calculations and evaluation of nuclear fuel containing Gadolinum it was decided to carry out a series of test calculations for fuel assembly lattices of PWR, WWER-440 and WWER-1000 types using the NESSEL/PYTHIA and CASMO/SIMULATE code systems (Authors)

  13. Application of a hybrid method based on the combination of genetic algorithm and Hopfield neural network for burnable poison placement

    International Nuclear Information System (INIS)

    Khoshahval, F.; Fadaei, A.

    2012-01-01

    Highlights: ► The performance of GA, HNN and combination of them in BPP optimization in PWR core are adequate. ► It seems HNN + GA arrives to better final parameter value in comparison with the two other methods. ► The computation time for HNN + GA is higher than GA and HNN. Thus a trade-off is necessary. - Abstract: In the last decades genetic algorithm (GA) and Hopfield Neural Network (HNN) have attracted considerable attention for the solution of optimization problems. In this paper, a hybrid optimization method based on the combination of the GA and HNN is introduced and applied to the burnable poison placement (BPP) problem to increase the quality of the results. BPP in a nuclear reactor core is a combinatorial and complicated problem. Arrangement and the worth of the burnable poisons (BPs) has an impressive effect on the main control parameters of a nuclear reactor. Improper design and arrangement of the BPs can be dangerous with respect to the nuclear reactor safety. In this paper, increasing BP worth along with minimizing the radial power peaking are considered as objective functions. Three optimization algorithms, genetic algorithm, Hopfield neural network optimization and a hybrid optimization method, are applied to the BPP problem and their efficiencies are compared. The hybrid optimization method gives better result in finding a better BP arrangement.

  14. Implementation of strength pareto evolutionary algorithm II in the multiobjective burnable poison placement optimization of KWU pressurized water reactor

    International Nuclear Information System (INIS)

    Gharari, Rahman; Poursalehi, Navid; Abbasi, Mohmmadreza; Aghale, Mahdi

    2016-01-01

    In this research, for the first time, a new optimization method, i.e., strength Pareto evolutionary algorithm II (SPEA-II), is developed for the burnable poison placement (BPP) optimization of a nuclear reactor core. In the BPP problem, an optimized placement map of fuel assemblies with burnable poison is searched for a given core loading pattern according to defined objectives. In this work, SPEA-II coupled with a nodal expansion code is used for solving the BPP problem of Kraftwerk Union AG (KWU) pressurized water reactor. Our optimization goal for the BPP is to achieve a greater multiplication factor (K-e-f-f) for gaining possible longer operation cycles along with more flattening of fuel assembly relative power distribution, considering a safety constraint on the radial power peaking factor. For appraising the proposed methodology, the basic approach, i.e., SPEA, is also developed in order to compare obtained results. In general, results reveal the acceptance performance and high strength of SPEA, particularly its new version, i.e., SPEA-II, in achieving a semioptimized loading pattern for the BPP optimization of KWU pressurized water reactor

  15. Implementation of strength pareto evolutionary algorithm II in the multiobjective burnable poison placement optimization of KWU pressurized water reactor

    Energy Technology Data Exchange (ETDEWEB)

    Gharari, Rahman [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Poursalehi, Navid; Abbasi, Mohmmadreza; Aghale, Mahdi [Nuclear Engineering Dept, Shahid Beheshti University, Tehran (Iran, Islamic Republic of)

    2016-10-15

    In this research, for the first time, a new optimization method, i.e., strength Pareto evolutionary algorithm II (SPEA-II), is developed for the burnable poison placement (BPP) optimization of a nuclear reactor core. In the BPP problem, an optimized placement map of fuel assemblies with burnable poison is searched for a given core loading pattern according to defined objectives. In this work, SPEA-II coupled with a nodal expansion code is used for solving the BPP problem of Kraftwerk Union AG (KWU) pressurized water reactor. Our optimization goal for the BPP is to achieve a greater multiplication factor (K-e-f-f) for gaining possible longer operation cycles along with more flattening of fuel assembly relative power distribution, considering a safety constraint on the radial power peaking factor. For appraising the proposed methodology, the basic approach, i.e., SPEA, is also developed in order to compare obtained results. In general, results reveal the acceptance performance and high strength of SPEA, particularly its new version, i.e., SPEA-II, in achieving a semioptimized loading pattern for the BPP optimization of KWU pressurized water reactor.

  16. Uranium enrichment

    International Nuclear Information System (INIS)

    1991-08-01

    This paper reports that in 1990 the Department of Energy began a two-year project to illustrate the technical and economic feasibility of a new uranium enrichment technology-the atomic vapor laser isotope separation (AVLIS) process. GAO believes that completing the AVLIS demonstration project will provide valuable information about the technical viability and cost of building an AVLIS plant and will keep future plant construction options open. However, Congress should be aware that DOE still needs to adequately demonstrate AVLIS with full-scale equipment and develop convincing cost projects. Program activities, such as the plant-licensing process, that must be completed before a plant is built, could take many years. Further, an updated and expanded uranium enrichment analysis will be needed before any decision is made about building an AVLIS plant. GAO, which has long supported legislation that would restructure DOE's uranium enrichment program as a government corporation, encourages DOE's goal of transferring AVLIS to the corporation. This could reduce the government's financial risk and help ensure that the decision to build an AVLIS plant is based on commercial concerns. DOE, however, has no alternative plans should the government corporation not be formed. Further, by curtailing a planned public access program, which would have given private firms an opportunity to learn about the technology during the demonstration project, DOE may limit its ability to transfer AVLIS to the private sector

  17. Concept and nuclear performance of direct-enrichment fusion breeder blanket using UO2 powder

    International Nuclear Information System (INIS)

    Oka, Yoshiaki; Kasahara, Takayasu; An, Shigehiro

    1985-01-01

    A new concept is presented for direct enrichment of fissile fuel in the blanket of a fusion-fission hybrid reactor. The enriched fuel produced by this means can be used in fission reactors without reprocessing. The outstanding feature of the concept is the powdered form in which UO 2 fuel is placed in the reactor blanket, where it is irradiated to the requisite enrichment for use as fuel in burner reactor, e.g. 3%. After removal from blanket, the powder is mixed to homogenize the enrichment. Fuel pellets and assemblies are then fabricated from the powder without reprocessing. The concept of irradiating UO 2 in powder eliminates the problems of spatial nonuniformity in fissile enrichment, and of radiation damage to fuel clad, encountered in attempting to enrich prefabricated fuel. Powder mixing for homogenization brings the additional benefit of removing volatile fission products. Also burnable poison can be added, as necessary, after irradiation. An extensive neutronic parameter survey showed that the optimum blanket arrangement for this enrichment concept is one presenting a fission suppressing configuration and with beryllium adopted as moderator. By this arrangement, the average 239 Pu enrichment obtained on the natural UO 2 fuel in the blanket reaches 3% after only 0.56 MW.yr/m"2 exposure. A conceptual design is presented of the blanket, together with associated fusion breeder, from which, practical application of the concept is shown to be promising. (author)

  18. Uranium enrichment

    International Nuclear Information System (INIS)

    1991-11-01

    This paper analyzes under four different scenarios the adequacy of a $500 million annual deposit into a fund to pay for the cost of cleaning up the Department of Energy's (DOE) three aging uranium enrichment plants. These plants are located in Oak Ridge, Tennessee; Paducah, Kentucky; and Portsmouth, Ohio. In summary the following was found: A fixed annual $500 million deposit made into a cleanup fund would not be adequate to cover total expected cleanup costs, nor would it be adequate to cover expected decontamination and decommissioning (D and D) costs. A $500 million annual deposit indexed to an inflation rate would likely be adequate to pay for all expected cleanup costs, including D and D costs, remedial action, and depleted uranium costs

  19. The effects of thermal annealing on the structure and the electrical transport properties of ultrathin gadolinia-doped ceria films grown by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigo, K.; Pryds, N.; Theil Kuhn, L.; Esposito, V.; Linderoth, S. [Technical University of Denmark, Fuel Cells and Solid State Chemistry Division, Risoe DTU, Roskilde (Denmark); Heiroth, S.; Lippert, T. [Paul Scherrer Institute, General Energy Research Department, Villigen PSI (Switzerland); Schou, J. [Technical University of Denmark, Department of Photonics Engineering, Roskilde (Denmark)

    2011-09-15

    Ultrathin crystalline films of 10 mol% gadolinia-doped ceria (CGO10) are grown on MgO (100) substrates by pulsed laser deposition at a moderate temperature of 400 C. As-deposited CGO10 layers of approximately 4 nm, 14 nm, and 22 nm thickness consist of fine grains with dimensions {<=}{proportional_to}11 nm. The films show high density within the thickness probed in the X-ray reflectivity experiments. Thermally activated grain growth, density decrease, and film surface roughening, which may result in the formation of incoherent CGO10 islands by dewetting below a critical film thickness, are observed upon heat treatment at 400 C and 800 C. The effect of the grain coarsening on the electrical characteristics of the layers is investigated and discussed in the context of a variation of the number density of grain boundaries. The results are evaluated with regard to the use of ultrathin CGO10 films as seeding templates for the moderate temperature growth of thick solid electrolyte films with improved oxygen transport properties. (orig.)

  20. Development of neural network simulating power distribution of a BWR fuel bundle

    International Nuclear Information System (INIS)

    Tanabe, A.; Yamamoto, T.; Shinfuku, K.; Nakamae, T.

    1992-01-01

    A neural network model is developed to simulate the precise nuclear physics analysis program code for quick scoping survey calculations. The relation between enrichment and local power distribution of BWR fuel bundles was learned using two layers neural network (ENET). A new model is to introduce burnable neutron absorber (Gadolinia), added to several fuel rods to decrease initial reactivity of fresh bundle. The 2nd stages three layers neural network (GNET) is added on the 1st stage network ENET. GNET studies the local distribution difference caused by Gadolinia. Using this method, it becomes possible to survey of the gradients of sigmoid functions and back propagation constants with reasonable time. Using 99 learning patterns of zero burnup, good error convergence curve is obtained after many trials. This neural network model is able to simulate no learned cases fairly as well as the learned cases. Computer time of this neural network model is about 100 times faster than a precise analysis model. (author)

  1. Nuclear fuel rod with burnable plate and pellet-clad interaction fix

    International Nuclear Information System (INIS)

    Boyle, R.F.

    1987-01-01

    This patent describes a nuclear fuel rod comprising a metallic tubular cladding containing nuclear fuel pellets, the pellets containing enriched uranium-235. The improvement described here comprises: ceramic wafers, each wafter comprising a sintered mixture of gadolinium oxide and uranium dioxide, the uranium oxide having no more uranium-235 than is present in natural uranium dioxide. Each of the wafers is axially disposed between a major portion of adjacent the nuclear fuel pellets, whereby the wafers freeze out volatile fission products produced by the nuclear fuel and prevent interaction of the fission products with the metallic tubing cladding

  2. Pilas de combustible de una sola cámara, basadas en electrolitos de ceria dopada con gadolinia y operadas con metano y propano

    Directory of Open Access Journals (Sweden)

    Piñol, S.

    2010-02-01

    Full Text Available The main advantages of single-chamber solid oxide fuel cells (SOFCs respect to dual-chamber SOFCs, are to simplify the device design and to operate in mixtures of hydrocarbon (methane, propane… and air, with no separation between fuel and oxidant. However, this design requires the use of selective electrodes for the fuel oxidation and the oxidant reduction. In this work, electrolyte-supported SOFCs were fabricated using gadolinia doped ceria (GDC as the electrolyte, Ni + GDC as the anode and LSC(La0.5Sr0.5CoO3-δ-GDC-Ag2O as the cathode. The electrical properties of the cell were determined in mixtures of methane + air and propane + air. The influence of temperature, gas composition and total flow rate on the fuel cell performance was investigated. As a result, the power density was strongly increased with increasing temperature, total flow rate and hydrocarbon composition. Under optimized gas compositions and total flow conditions, power densities of 70 and 320 mW/cm2 operating on propane at a temperature of 600ºC and methane (795ºC were obtained, respectively.

    La principal ventaja de las pilas de combustible de óxido sólido (SOFCs de una sola cámara, frente a las bicamerales convencionales, es que permiten simplificar el diseño del dispositivo y operar con mezclas de hidrocarburos (metano, propano... y aire, sin necesidad de separar ambos gases, por medio del uso de electrodos selectivos a la oxidación del combustible y reducción del oxidante. En el presente trabajo, se han fabricado monopilas soportadas sobre electrolitos de ceria dopada con gadolinia (GDC, de 200 µm de espesor, usando Ni-GDC como ánodo y LSC(La0.5Sr0.5CoO3-δ-GDC-Ag2O como cátodo. Las propiedades eléctricas de la celda se determinaron en un reactor de una sola cámara, usando mezclas de metano + aire y propano + aire. Se investigó la influencia de la

  3. Sintering, microstructure and electrical conductivity of gadolinia-doped ceria with SrO, TiO2 and SrTiO3

    International Nuclear Information System (INIS)

    Dias, Maria Cely Freitas

    2013-01-01

    Ceria containing trivalent rare-earths is a solid electrolyte with higher ionic conductivity than the standard yttria fully-stabilized zirconia ionic conductor. This property turns these ceria-based ionic conductors promising materials for application in solid oxide fuel cells operating at intermediate temperatures (500-700 deg C). One of the most utilized approaches to optimize the electrical conductivity and other properties of these materials is the introduction of a second additive. In this work, ceria-20 mol% gadolinia with additions of 1, 2.5 and 5 mol% of SrO, TiO 2 and SrTiO 3 as co-additives were prepared by solid state reaction. The main purpose was to investigate the effects of the co-additives on densification, microstructure and electrical conductivity of the solid electrolyte. Sintered pellets were characterized by apparent density, X-ray diffraction, Raman spectroscopy, scanning electron microscopy and electrical conductivity by impedance spectroscopy. The additives were found to exert different influences in all studied properties. The way they influence the solid electrolyte properties depends on the type and content of the additive. SrO addition to doped ceria improves the intergranular conductivity, but decreases the apparent density of the pellets. Increase of densification was obtained with TiO 2 addition. This additive promotes increase of the blocking of charge carriers at the grain boundaries due to solute exsolution and formation of the pyrochlore Gd 2 Ti 2 O 7 phase at grain boundaries for contents in excess of the solubility limit. No influence on densification was found for SrTiO 3 additions. (author)

  4. Juvenile psittacine environmental enrichment.

    Science.gov (United States)

    Simone-Freilicher, Elisabeth; Rupley, Agnes E

    2015-05-01

    Environmental enrichment is of great import to the emotional, intellectual, and physical development of the juvenile psittacine and their success in the human home environment. Five major types of enrichment include social, occupational, physical, sensory, and nutritional. Occupational enrichment includes exercise and psychological enrichment. Physical enrichment includes the cage and accessories and the external home environment. Sensory enrichment may be visual, auditory, tactile, olfactory, or taste oriented. Nutritional enrichment includes variations in appearance, type, and frequency of diet, and treats, novelty, and foraging. Two phases of the preadult period deserve special enrichment considerations: the development of autonomy and puberty. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Study and optimization of the composite nuclear fuel with burnable poison UO2/Gd2O3

    International Nuclear Information System (INIS)

    Balestrieri, D.

    1995-09-01

    The studied composite ceramics is a nuclear fuel constituted of a uranium dioxide matrix UO 2 in which big grains (or 'macro-masses') of gadolinium oxide (Gd 2 O 3 ) of 300 ± 100 μm of diameter (mass fraction of 12%) are dispersed. Used as burnable poison (neutron absorbent whose action disappears progressively during the irradiation), gadolinium oxide is the object of a particular attention because some of its properties as the crystal structure, the aptitude to sintering and the thermomechanical behavior have been studied. The aim of this work is to perfect and optimize the process of manufacture of the composite in order to answer to accurate specifications for the density, the shape and the mass fraction of macro-masses. In this framework, it has been necessary to strengthen the Gd 2 O 3 macro-masses by a thermal treatment in order to avoid their deformation during the uniaxial pressing. The influence of this pre-consolidation on the ended microstructure, the aptitude to sintering and the thermal conductivity of the composite have been studied. (O.M.)

  6. Other enrichment related contracts

    International Nuclear Information System (INIS)

    Hall, J.C.

    1978-01-01

    In addition to long-term enrichment contracts, DOE has other types of contracts: (1) short-term, fixed-commitment enrichment contract; (2) emergency sales agreement for enriched uranium; (3) feed material lease agreement; (4) enriched uranium storage agreement; and (5) feed material usage agreement

  7. Substitution of the soluble boron reactivity control system of a pressurized water reactor by gadolinium burnable poisons

    International Nuclear Information System (INIS)

    Galperin, A.; Segev, M.; Radkowsky, A.

    1986-01-01

    The results are presented of a research project that is aimed at designing a gadolinium burnable poison (BP) system for complete reactivity control of a pressurized water reactor (PWR) core during the ''equilibrium'' cycle, resulting in the elimination of the soluble boron system, which represents a considerable saving in both capital and operating costs. A flat and strong negative moderator temperature coefficient is assured for a poison-free moderator. The design analysis of a core, heavily loaded with gadolinium BP rods, was based on a BGUCORE neutronic package and cluster model of a fuel assembly. The project objective was achieved by a novel lumped BP rod, designed as an annulus of gadolinium, clad by zirconium, and inserted into vacant guide thimbles of fresh-fuel assemblies. Specific combinations were found for the inner/outer radii of the poison ring, gadolinium densities, and number of rods per assembly, resulting in an almost flat criticality curve during the cycle. A reactivity swing of ≅1% ΔK can be easily controlled by an existing system of control rods. Comparison of the fuel cycle length of a gadolinium-controlled core with that of the reference, soluble, boron-controlled core indicated that there is no penalty due to residual poison at end of life. Unique guidelines for the fuel loading strategy were applied to find a practical fuel-shuffling scheme by which the design and operational constraints of a typical PWR core of current design were satisfied. Several problems should be solved for a practical implementation of the presented design relative to operational and safety requirements of the existing control rod system. Adequate movement of the regulating rods should be determined and shutdown margins of the safety rods should be ascertained. Final judgment of the feasibility of the concept may be made following the solution of these and other regulatory-related issues

  8. Burnable poisons in the light water reactor design, microburnup experiments and calculations. Part of a coordinated programme on burnup calculations and experiments for thermal reactors

    International Nuclear Information System (INIS)

    Penndorf, K.

    1976-04-01

    Investigations on Research Agreement N 1519/CF (1.8.1974 - 31.7.1975) entitled ''Burnable poisons in light water reactor design, microburnup experiments and calculations'' were carried out in the frame of the IAEA's coordinated research programme on ''Burn-up calculation and experiments for thermal reactors''. The theoretical and experimental work on application of solid burnable poison used for reduction of the amount of boric acid necessary to control of PWR or to lower the number of control rods needed in a BWR. Solid burnable poisons are needed in present PWR designs for the reduction of the boron acid concentration in order to prevent positive coefficients of reactivity. The special operational conditions of a ship reactor lead to the application of this kind of poison for compensation of almost all burnup reactivity. This strengthens the necessity of a very accurate and many dimensional calculations because an appropriate binding of reactivity has to be kept over the whole cycle time. Several burnup experiments had been run in the 15 MW material test reactor FRG-II. The following devices have been irradiated: poison pins within and without PWR fuel pin lattice segments and fuel pins containing pellets with a poison core. Measurements of reactivity, fluence, fission product concentration have been performed. Methods applied were γ-scanning and neutron pulse, radiography and transmission measurement techniques. Evaluation of the experiments was done by one and two dimensional Ssub(N) transport burnup calculations. In parallel a collision probability transport burnup code for current PWR design work is being developed, the main feature of which is economy in manpower and computer time

  9. Application of B{sub 4}C/Al{sub 2}O{sub 3} Burnable Absorber Rod to Control Excess Reactivity of SMR

    Energy Technology Data Exchange (ETDEWEB)

    Muth, Boravy; Hah, C. J. [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2016-10-15

    Soluble boron in a nuclear reactor coolant is one of the methods to control excess reactivity of the reactor. However, the use of soluble boron also causes some negative effects such as corrosion, more-positive tendency of Moderator Temperature Coefficient (MTC) and the requirement of Chemical Volume Control System (CVCS). One of the conceptual design features of SMR having been developed in Korea is soluble boron- free reactor to eliminate those drawbacks. Control rods and Burnable Absorber (BA) rods can be other methods than soluble to control excess reactivity. WABA (Wet Annular Burnable Absorber) and PYREX are such type. The other type is IFBA (Integral Fuel Burnable Absorber) in which fuel pellet surface is coated with BA. This paper compares nuclear characteristics of three types of BA as well as SLOBA in terms of k-infinite vs. burnup and explain design basis of SLOBA. This paper also presents the application of SLOBA rods to control long-term excess reactivity of SMR. The SMR loaded with SLOBA rods has been developed for the past few years in Korean. It is named as Bandi-50 with design features of 180 MWth, 37 FAs, fuel assembly height of 200 cm. Soluble-boron-free is one of nuclear design requirements of Bandi-50 and is achieved by controlling excess reactivity of the SMR using BAs and control rods only. To achieve this design requirement, LP is carefully determined in such way that CBC should be as low as possible. Fuel assembly cross-sections are generated by CASMO-3, and core depletion calculations are performed by MASTER.

  10. Derived enriched uranium market

    International Nuclear Information System (INIS)

    Rutkowski, E.

    1996-01-01

    The potential impact on the uranium market of highly enriched uranium from nuclear weapons dismantling in the Russian Federation and the USA is analyzed. Uranium supply, conversion, and enrichment factors are outlined for each country; inventories are also listed. The enrichment component and conversion components are expected to cause little disruption to uranium markets. The uranium component of Russian derived enriched uranium hexafluoride is unresolved; US legislation places constraints on its introduction into the US market

  11. DESCRIPTION OF THE TRITIUM-PRODUCING BURNABLE ABSORBER ROD FOR THE COMMERCIAL LIGHT WATER REACTOR TTQP-1-015 Rev 19

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Kimberly A.; Love, Edward F.; Thornhill, Cheryl K.

    2012-02-01

    Tritium-producing burnable absorber rods (TPBARs) used in the U.S. Department of Energy’s Tritium Readiness Program are designed to produce tritium when placed in a Westinghouse or Framatome 17x17 fuel assembly and irradiated in a pressurized water reactor (PWR). This document provides an unclassified description of the current design baseline for the TPBARs. This design baseline is currently valid only for Watts Bar reactor production cores. A description of the Lead Use TPBARs will not be covered in the text of the document, but the applicable drawings, specifications and test plan will be included in the appropriate appendices.

  12. Uranium enrichment plans

    International Nuclear Information System (INIS)

    Thomas, D.C.; Gagne, R.W.

    1978-01-01

    The following topics are covered: the status of the Government's existing uranium enrichment services contracts, natural uranium requirements based on the latest contract information, uncertainty in predicting natural uranium requirements based on uranium enrichment contracts, and domestic and foreign demand assumed in enrichment planning

  13. Sintering, microstructure and electrical conductivity of gadolinia-doped ceria with SrO, TiO{sub 2} and SrTiO{sub 3}; Sinterizacao, microestrutura e condutividade eletrica da ceria-gadolinia com adicoes de SrO, TiO{sub 2} e SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Maria Cely Freitas

    2013-07-01

    Ceria containing trivalent rare-earths is a solid electrolyte with higher ionic conductivity than the standard yttria fully-stabilized zirconia ionic conductor. This property turns these ceria-based ionic conductors promising materials for application in solid oxide fuel cells operating at intermediate temperatures (500-700 deg C). One of the most utilized approaches to optimize the electrical conductivity and other properties of these materials is the introduction of a second additive. In this work, ceria-20 mol% gadolinia with additions of 1, 2.5 and 5 mol% of SrO, TiO{sub 2} and SrTiO{sub 3} as co-additives were prepared by solid state reaction. The main purpose was to investigate the effects of the co-additives on densification, microstructure and electrical conductivity of the solid electrolyte. Sintered pellets were characterized by apparent density, X-ray diffraction, Raman spectroscopy, scanning electron microscopy and electrical conductivity by impedance spectroscopy. The additives were found to exert different influences in all studied properties. The way they influence the solid electrolyte properties depends on the type and content of the additive. SrO addition to doped ceria improves the intergranular conductivity, but decreases the apparent density of the pellets. Increase of densification was obtained with TiO{sub 2} addition. This additive promotes increase of the blocking of charge carriers at the grain boundaries due to solute exsolution and formation of the pyrochlore Gd{sub 2}Ti{sub 2}O{sub 7} phase at grain boundaries for contents in excess of the solubility limit. No influence on densification was found for SrTiO{sub 3} additions. (author)

  14. Uranium Enrichment, an overview

    International Nuclear Information System (INIS)

    Coates, J.H.

    1994-01-01

    This general presentation on uranium enrichment will be followed by lectures on more specific topics including descriptions of enrichment processes and assessments of the prevailing commercial and industrial situations. I shall therefore avoid as much as possible duplications with these other lectures, and rather dwell on: some theoretical aspects of enrichment in general, underlying the differences between statistical and selective processes, a review and comparison between enrichment processes, remarks of general order regarding applications, the proliferation potential of enrichment. It is noteworthy that enrichment: may occur twice in the LWR fuel cycle: first by enriching natural uranium, second by reenriching uranium recovered from reprocessing, must meet LWR requirements, and in particular higher assays required by high burn up fuel elements, bears on the structure of the entire front part of the fuel cycle, namely in the conversion/reconversion steps only involving UF 6 for the moment. (author). tabs., figs., 4 refs

  15. Evaluation of accuracy of Monte Carlo code MVP with VHTRC experiments. Multiplication factor at criticality, burnable poison worth and void worth

    International Nuclear Information System (INIS)

    Nojiri, Naoki; Yamashita, Kiyonobu; Fiujimoto, Nozomu; Nakano, Masaaki , Yamane, Tsuyoshi; Akino, Fujiyoshi.

    1997-11-01

    Experimental data of VHTRC (Very High Temperature Reactor Critical Assembly) were analyzed using Monte Carlo code MVP (general purpose Monte Carlo code of neutron and photon transport calculations based on the continuous energy method). The calculation accuracy of the code was evaluated by the analysis for nuclear characteristics of a HTGR (high temperature gas-cooled reactor). The MVP code can analyze with a detailed three-dimensional core model with a few approximations. The HTGRs have following characteristics from view point of nuclear design : they have burnable poisons, many void holes, namely, the control insertion holes and so on. Taking account of these characteristics, multiplication factor at criticality, burnable poison worth, and void worth were evaluated. The maximum calculation errors were 0.8%Δk, 7%, and 25% respectively, From these results, it can be concluded that the MVP code is able to be applied to the nuclear characteristics analysis of the HTGR like the High Temperature Engineering Test Reactor (HTTR). (author)

  16. Advanced enrichment techniques

    International Nuclear Information System (INIS)

    Johnson, A.

    1988-01-01

    BNFL is in a unique position in that it has commercial experience of diffusion enrichment, and of centrifuge enrichment through its associate company Urenco. In addition BNFL is developing laser enrichment techniques as part of a UK development programme in this area. The paper describes the development programme which led to the introduction of competitive centrifuge enrichment technology by Urenco and discusses the areas where improvements have and will continue to be made in the centrifuge process. It also describes the laser development programme currently being undertaken in the UK. The paper concludes by discussing the relative merits of the various methods of uranium enrichment, with particular reference to the enrichment market likely to obtain over the rest of the century

  17. Advanced enrichment techniques

    International Nuclear Information System (INIS)

    Johnson, A.

    1987-01-01

    BNFL is in a unique position in that it has commercial experience of diffusion enrichment, and of centrifuge enrichment through its associate company Urenco. In addition BNFL is developing laser enrichment techniques as part of a UK development programme in this area. The paper describes the development programme which led to the introduction of competitive centrifuge enrichment technology by Urenco and discusses the areas where improvements have and will continue to be made in the centrifuge process. It also describes the laser development programme currently being undertaken in the UK. The paper concludes by discussing the relative merits of the various methods of uranium enrichment, with particular reference to the enrichment market likely to obtain over the rest of the century. (author)

  18. Uranium enrichment: an overview

    International Nuclear Information System (INIS)

    Cazalet, J.

    1995-01-01

    This paper is a general presentation of uranium enrichment processes and assessments of the prevailing commercial and industrial situations. It gives first some theoretical aspects of enrichment in general and explains the differences between statistical and selective processes in particular. Then a review of the different processes is made with a comparison between them. Finally, some general remarks concerning applications are given and the risks of proliferation related to enrichment are mentioned. (J.S.). 4 refs., 5 figs., 8 tabs

  19. The enrichment secondary market

    International Nuclear Information System (INIS)

    Einbund, D.R.

    1986-01-01

    This paper will addresses two topics: the background to the present status of the enrichment secondary market and the future outlook of the secondary market in enrichment services, and the viability of the nuclear fuel brokerage industry. These two topics are inevitably connected, as most secondary market activity, not only in enrichment but also in natural uranium, has traditionally been conducted with the participation of brokers. Therefore, the author interrelates these topics

  20. Uranium enrichment plans

    International Nuclear Information System (INIS)

    Gagne, R.W.; Thomas, D.C.

    1977-01-01

    The status of existing uranium enrichment contracts in the US is reviewed and expected natural uranium requirements for existing domestic uranium enrichment contracts are evaluated. Uncertainty in natural uranium requirements associated with requirements-type and fixed-commitment type contracts is discussed along with implementation of variable tails assay

  1. The slightly-enriched spectral shift control reactor

    Energy Technology Data Exchange (ETDEWEB)

    Martin, W.R.; Lee, J.C.; Larsen, E.W. (Michigan Univ., Ann Arbor, MI (United States). Dept. of Nuclear Engineering); Edlund, M.C. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Mechanical and Nuclear Engineering)

    1991-11-01

    An advanced converter reactor design utilizing mechanical spectral shift control rods in a conventional pressurized water reactor configuration is under investigation. The design is based on the principle that a harder spectrum during the early part of the fuel cycle will result in large neutron captures in fertile {sup 238}U, which can then be burned in situ in a softer spectrum later in the cycle. Preliminary design calculations performed during FY 89 showed that the slightly-enriched spectral shift reactor design offers the benefit of substantially increased fuel resource utilization with the proven safety characteristics of the pressurized water reactor technology retained. Optimization of the fuel design and development of fuel management strategies were carried out in FY 90, along with effort to develop and validate neutronic methodology for tight-lattice configurations with hard spectra. During FY 91, the final year of the grant, the final Slightly-Enriched Spectral Shift Reactor (SESSR) design was determined, and reference design analyses were performed for the assemblies as well as the global core configuration, both at the beginning of cycle (BOC) and with depletion. The final SESSR design results in approximately a 20% increase in the utilization of uranium resources, based on equilibrium fuel cycle analyses. Acceptable pin power peaking is obtained with the final core design, with assembly peaking factors equal to less than 1.04 for spectral shift control rods both inserted and withdrawn, and global peaking factors at BOC predicted to be 1.4. In addition, a negative Moderation Temperature Coefficient (MTC) is maintained for BOC, which is difficult to achieve with conventional advanced converter designs based on a closed fuel cycle. The SESSR design avoids the need for burnable poison absorber, although they could be added if desired to increase the cycle length while maintaining a negative MTC.

  2. The slightly-enriched spectral shift control reactor

    International Nuclear Information System (INIS)

    Martin, W.R.; Lee, J.C.; Larsen, E.W.; Edlund, M.C.

    1991-11-01

    An advanced converter reactor design utilizing mechanical spectral shift control rods in a conventional pressurized water reactor configuration is under investigation. The design is based on the principle that a harder spectrum during the early part of the fuel cycle will result in large neutron captures in fertile 238 U, which can then be burned in situ in a softer spectrum later in the cycle. Preliminary design calculations performed during FY 89 showed that the slightly-enriched spectral shift reactor design offers the benefit of substantially increased fuel resource utilization with the proven safety characteristics of the pressurized water reactor technology retained. Optimization of the fuel design and development of fuel management strategies were carried out in FY 90, along with effort to develop and validate neutronic methodology for tight-lattice configurations with hard spectra. During FY 91, the final year of the grant, the final Slightly-Enriched Spectral Shift Reactor (SESSR) design was determined, and reference design analyses were performed for the assemblies as well as the global core configuration, both at the beginning of cycle (BOC) and with depletion. The final SESSR design results in approximately a 20% increase in the utilization of uranium resources, based on equilibrium fuel cycle analyses. Acceptable pin power peaking is obtained with the final core design, with assembly peaking factors equal to less than 1.04 for spectral shift control rods both inserted and withdrawn, and global peaking factors at BOC predicted to be 1.4. In addition, a negative Moderation Temperature Coefficient (MTC) is maintained for BOC, which is difficult to achieve with conventional advanced converter designs based on a closed fuel cycle. The SESSR design avoids the need for burnable poison absorber, although they could be added if desired to increase the cycle length while maintaining a negative MTC

  3. Developments in uranium enrichment

    International Nuclear Information System (INIS)

    Mohrhauer, H.

    1995-01-01

    The enrichment services market is still characterized by overcapacities. While consumption worldwide will rise by some 15% to 39,000 t SWU/a over the next ten years, capacities amount to nearly 50,000 t SWU/a. The price for enrichment services probably has reached its all time low. Prices below U.S. $ 100/kg SWU are not likely to cover costs even of the economically most advanced enrichment processes. Urenco has prepared for the difficult enrichment business in the years to come by streamlining and cost cutting measures. The company intends to hold and increase its share of more than 10% in the world market. The uranium enrichment plant of Gronau will be expanded further. Expansion beyond 1000 t is subject to another permit being granted under the Atomic Energy Act, an application for which was filed in December 1994. Centrifuge technology is the superior enrichment technology, i.e., there is still considerable potential for further development. Construction of enrichment plants employing the centrifuge technology in the United States and in France is being pursued in various phases, from feasibility studies to licensing procedures. Before these plants could be implemented, however, considerable problems of organization would have to be solved, and the market would have to change greatly, respectively. The laser process, at the present time, does not seem to be able to develop into a major industrial competitor. (orig.) [de

  4. TRIGA low enrichment fuel

    International Nuclear Information System (INIS)

    Gietzen, A.

    1993-01-01

    Sixty TRIGA reactors have been sold and the earliest of these are now passing twenty years of operation. All of these reactors use the uranium zirconium hydride fuel (UZrH) which provides certain unique advantages arising out of its large prompt negative temperature coefficient, very low fission product release, and high temperature capability. Eleven of these Sixty reactors are conversions from plate fuel to TRIGA fuel which were made as a result of these advantages. With only a few exceptions, TRIGA reactors have always used low-enriched uranium (LEU) fuel with an enrichment of 19.9%. The exceptions have either been converted from the standard low-enriched fuel to the 70% enriched FLIP fuel in order to achieve extended lifetime, or are higher powered reactors which were designed for long life using 93%-enriched uranium during the time when the use and export of highly enriched uranium (HEU) was not restricted. The advent of international policies focusing attention on nonproliferation and safeguards made the HEU fuels obsolete. General Atomic immediately undertook a development effort (nearly two years ago) in order to be in a position to comply with these policies for all future export sales and also to provide a low-enriched alternative to fully enriched plate-type fuels. This important work was subsequently partially supported by the U.S. Department of Energy. The laboratory and production tests have shown that higher uranium densities can be achieved to compensate for reducing the enrichment to 20%, and that the fuels maintain the characteristics of the very thoroughly proven standard TRIGA fuels. In May of 1978, General Atomic announced that these fuels were available for TRIGA reactors and for plate-type reactors with power levels up to 15 MW with General Atomic's standard commercial warranty

  5. TRIGA low enrichment fuel

    International Nuclear Information System (INIS)

    Gietzen, A.

    1993-01-01

    Sixty TRIGA reactors have been sold and the earliest of these are now passing twenty years of operation. All of these reactors use the uranium-zirconium hydride fuel (UZrH) which provides certain unique advantages arising out of its large prompt negative temperature coefficient, very low fission product release, and high temperature capability. Eleven of these Sixty reactors are conversions from plate fuel to TRIGA fuel which were made as a result of these advantages. With only a few exceptions, TRIGA reactors have always used low-enriched-uranium (LEU) fuel with an enrichment of 19.9%. The exceptions have either been converted from the standard low-enriched fuel to the 70% enriched FLIP fuel in order to achieve extended lifetime, or are higher powered reactors which were designed for long life using 93%-enriched uranium during the time when the use and export of highly enriched uranium (HEU) was not restricted. The advent of international policies focusing attention on nonproliferation and safeguards made the HEU fuels obsolete. General Atomic immediately undertook a development effort (nearly two years ago) in order to be in a position to comply with these policies for all future export sales and also to provide a low-enriched alternative to fully enriched plate-type fuels. This important work was subsequently partially supported by the U.S. Department of Energy. The laboratory and production tests have shown that higher uranium densities can be achieved to compensate for reducing the enrichment to 20%, and that the fuels maintain the characteristics of the very thoroughly proven standard TRIGA fuels. In May of 1978, General Atomic announced that these fuels were available for TRIGA reactors and for plate-type reactors with power levels up to 15 MW with GA's standard commercial warranty

  6. Nuclear fuel elements and assemblies

    International Nuclear Information System (INIS)

    Saito, Shozo; Maki, Hideo.

    1982-01-01

    Purpose: To facilitate the attainment of the uranium enrichment or gadolinia enrichment of a pellet filled in a fuel element. Constitution: The axial length of a pellet filled in a fuel element is set to predetermined sizes according to the uranium enrichment factor, gadolinia enrichment or their combination. Thus, the uranium enrichment factor or gadolinia enrichment can be identified by attaining the axial length of the pellet by using such a pellt. (Kamimura, M.)

  7. The competitive enrichment market

    International Nuclear Information System (INIS)

    Parks, J.W.; Huffman, F.C.

    1984-01-01

    With the enactment of the ''Private Ownership of Special Nuclear Materials Act'' in 1964, the U.S. Government made provisions to enter into the uranium enrichment services business. Since nuclear power was in its infancy and the Government was promoting its growth as well as trying to help U.S. industry sell reactors overseas, the initial contracts (Requirements Contracts) for enrichment services placed most of the risks associated with the supplying of the services on the Government. Projections of nuclear power additions continued to grow and in 1972 the Atomic Energy Commission (AEC) stopped contracting under Requirements Contracts in order to study which mode of contracting best suited the commercial development of the industry. In mid-1973, the AEC introduced the Long-Term Fixed Commitment (LTFC) contract which shifted the risk to the customer. By mid-1974, AEC had contracts which completely used the enrichment capacity of its complex and refused to accept requests for additional contracts. This action further convinced European nations that they should continue to develop their own enrichment capacity and resulted in the EURODIF and URENCO projects. Before this time the U.S. supplied 100% of the world market for enriching services

  8. Enrichment: Dealing with overcapacity

    International Nuclear Information System (INIS)

    Peterson, C.H.

    1989-01-01

    Today's surplus of enrichment capacity will continue until at least the end of this century. This will challenge the ingenuity of the separative work unit (SWU) suppliers as they attempt to keep market share and remain profitable in a very competitive marketplace. The utilities will be faced with attractive choices, but making the best choice will require careful analysis and increased attention to market factors. Current demand projections will probably prove too high to the extent that more reactors are canceled or delayed. The DOE has the vast majority of the unused capacity, so it will feel the most immediate impact of this large surplus in productive capacity. The DOE has responded to these market challenges by planning another reorganization of its enriching operations. Without a major agreement among the governments affected by the current surplus in enrichment capacity, the future will see lower prices, more competitive terms, and the gradual substitution of centrifuge or laser enrichment for the gaseous diffusion plants. The competition that is forcing the gaseous diffusion prices down to marginal cost will provide the long-term price basis for the enrichment industry

  9. Laser and gas centrifuge enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Heinonen, Olli [Senior Fellow, Belfer Center for Science and International Affairs, Harvard Kennedy School, Cambridge, Massachusetts (United States)

    2014-05-09

    Principles of uranium isotope enrichment using various laser and gas centrifuge techniques are briefly discussed. Examples on production of high enriched uranium are given. Concerns regarding the possibility of using low end technologies to produce weapons grade uranium are explained. Based on current assessments commercial enrichment services are able to cover the global needs of enriched uranium in the foreseeable future.

  10. Oxygen enrichment incineration

    International Nuclear Information System (INIS)

    Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung

    2000-10-01

    Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested

  11. Oxygen enrichment incineration

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung

    2000-10-01

    Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested.

  12. Centrifuge enrichment program

    International Nuclear Information System (INIS)

    Astley, E.R.

    1976-01-01

    Exxon Nuclear has been active in privately funded research and development of centrifuge enrichment technology since 1972. In October of 1975, Exxon Nuclear submitted a proposal to design, construct, and operate a 3000-MT SWU/yr centrifuge enrichment plant, under the provisions of the proposed Nuclear Fuel Assurance Act of 1975. The U.S. Energy Research and Development Administration (ERDA) accepted the proposal as a basis for negotiation. It was proposed to build a 1000-MT SWU/yr demonstration increment to be operational in 1982; and after successful operation for about one year, expand the facilities into a 3000-MT SWU/yr plant. As part of the overall centrifuge enrichment plant, a dedicated centrifuge manufacturing plant would be constructed; sized to support the full 3000-MT SWU/yr plant. The selection of the centrifuge process by Exxon Nuclear was based on an extremely thorough evaluation of current and projected enrichment technology; results show that the technology is mature and the process will be cost effective. The substantial savings in energy (about 93%) from utilization of the centrifuge option rather than gaseous diffusion is a compelling argument. As part of this program, Exxon Nuclear has a large hardware R and D program, plus a prototype centrifuge manufacturing capability in Malta, New York. To provide a full-scale machine and limited cascade test capability, Exxon Nuclear is constructing a $4,000,000 Centrifuge Test Facility in Richland, Washington. This facility was to initiate operations in the Fall of 1976. Exxon Nuclear is convinced that the centrifuge enrichment process is the rational selection for emergence of a commercial enrichment industry

  13. US enrichment reduction studies

    International Nuclear Information System (INIS)

    1979-06-01

    A major national program, the Reduced Enrichment Research and Test Reactor (RERTR) Program, is currently under way in the U.S., centered at the Argonne National Laboratory (ANL), to reduce the potential of research and test reactor fuels for increasing the proliferation of nuclear explosive devices. The main objective of the program is to provide the technical means by which the uranium enrichment to be used in these reactors can be reduced to less than 20% without significant economic and performance penalties. The criteria, basis and goals of the program are consistent with the results of a number of case studies which have been performed as part of the program

  14. Advanced uranium enrichment processes

    International Nuclear Information System (INIS)

    Clerc, M.; Plurien, P.

    1986-01-01

    Three advanced Uranium enrichment processes are dealt with in the report: AVLIS (Atomic Vapour LASER Isotope Separation), MLIS (Molecular LASER Isotope Separation) and PSP (Plasma Separation Process). The description of the physical and technical features of the processes constitutes a major part of the report. If further presents comparisons with existing industrially used enrichment technologies, gives information on actual development programmes and budgets and ends with a chapter on perspectives and conclusions. An extensive bibliography of the relevant open literature is added to the different subjects discussed. The report was drawn up by the nuclear research Centre (CEA) Saclay on behalf of the Commission of the European Communities

  15. Uranium Conversion & Enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-02-06

    The isotopes of uranium that are found in nature, and hence in ‘fresh’ Yellowcake’, are not in relative proportions that are suitable for power or weapons applications. The goal of conversion then is to transform the U3O8 yellowcake into UF6. Conversion and enrichment of uranium is usually required to obtain material with enough 235U to be usable as fuel in a reactor or weapon. The cost, size, and complexity of practical conversion and enrichment facilities aid in nonproliferation by design.

  16. Rare earths as burnable poison for extended cycles control in electricity generation reactors; Etude des terres rares en tant que poison consommable pour le controle des cycles allonges pour les reacteurs electrogenes

    Energy Technology Data Exchange (ETDEWEB)

    Asou, M

    1995-05-12

    The search of an optimization of the French electronuclear network operations leads to a necessary optimization of the core performances. All the economic studies performed by the utilities had shown that there is a real gain to minimize shut down periods for refueling. So, increasing the cycle length from 12 to 18 months will present a gain of shut down for a three years operation period. The theoretical burnable absorber will be a fuel admixed material bringing the required initial negative reactivity with a burn-up kinetic well suited to the fuel and allowing the lowest residual penalty as possible. The residual penalty us defined in this case by the non complete burn up of the poison, by the low of fissile material and by the accumulate of residual isotopes or nuclides. Because of the well known use of gadolinium as burnable absorber for BWR`s and PWR`s operations, the search for the best compromise to optimize all the above stress is pointed towards the rare earths. In the nuclides family, considering criteria such as cross sections, natural abundance and availability only five nuclides can play the role as burnable absorbers, namely: gadolinium, samarium, dysprosium, europium and erbium. The study presented here will show that only gadolinium and erbium will be considered to control the reactivity of the PWR`s. (author). 58 refs., 65 figs., 47 tabs.

  17. Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David [ORNL; Chandler, David [ORNL; Cook, David [ORNL; Ilas, Germina [ORNL; Jain, Prashant [ORNL; Valentine, Jennifer [ORNL

    2014-10-30

    Engineering design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy’s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU fuel is a new U-Mo monolithic fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the fuel can be fabricated to a specific reference design. Fabrication techniques for the new fuel are under development by the program but are still immature, especially for the “complex” aspects of the HFIR fuel design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU fuel. In support of this new focus and in an effort to ensure that the HFIR fuel design is as suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative design features. These features include (1) eliminating the fuel zone axial contouring in the previous reference design by substituting a permanent neutron absorber in the lower unfueled region of all of the fuel plates, (2) relocating the burnable neutron absorber from the fuel plates of the inner fuel element to the side plates of the inner fuel element (the fuel plates of the outer fuel element do not contain a burnable absorber), (3) relocating the fuel zone inside the fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated fuel zone to be symmetric about this centerline. The

  18. Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Renfro, David G [ORNL; Chandler, David [ORNL; Cook, David Howard [ORNL; Ilas, Germina [ORNL; Jain, Prashant K [ORNL; Valentine, Jennifer R [ORNL

    2014-11-01

    Engineering design studies of the feasibility of conversion of the High Flux Isotope Reactor (HFIR) from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel are ongoing at Oak Ridge National Laboratory (ORNL) as part of an effort sponsored by the U.S. Department of Energy s Global Threat Reduction Initiative (GTRI)/Reduced Enrichment for Research and Test Reactors (RERTR) program. The fuel type selected by the program for the conversion of the five high-power research reactors in the U.S. that still use HEU fuel is a new U-Mo monolithic fuel. Studies by ORNL have previously indicated that HFIR can be successfully converted using the new fuel provided (1) the reactor power can be increased from 85 MW to 100 MW and (2) the fuel can be fabricated to a specific reference design. Fabrication techniques for the new fuel are under development by the program but are still immature, especially for the complex aspects of the HFIR fuel design. In FY 2012, the program underwent a major shift in focus to emphasize developing and qualifying processes for the fabrication of reliable and affordable LEU fuel. In support of this new focus and in an effort to ensure that the HFIR fuel design is as suitable for reliable fabrication as possible, ORNL undertook the present study to propose and evaluate several alternative design features. These features include (1) eliminating the fuel zone axial contouring in the previous reference design by substituting a permanent neutron absorber in the lower unfueled region of all of the fuel plates, (2) relocating the burnable neutron absorber from the fuel plates of the inner fuel element to the side plates of the inner fuel element (the fuel plates of the outer fuel element do not contain a burnable absorber), (3) relocating the fuel zone inside the fuel plate to be centered on the centerline of the depth of the plate, and (4) reshaping the radial contour of the relocated fuel zone to be symmetric about this centerline. The present

  19. An Enriching Community.

    Science.gov (United States)

    Holland, Nancy A.; Burroughs, Jean

    2001-01-01

    Successful school-community partnerships in Volusia (Florida) Public Schools are the results of marketing creatively, meeting community members' needs, and bringing the right people together. The 3-year old program now offers students of all ages an expanding list of enrichment classes on many subjects for a nominal fee. (MLH)

  20. Uranium enrichment techniques

    International Nuclear Information System (INIS)

    Hamdoun, N.A.

    2007-01-01

    This article includes an introduction about the isotopes of natural uranium, their existence and the difficulty of the separation between them. Then it goes to the details of a number of methods used to enrich uranium: Gaseous Diffusion method, Electromagnetic method, Jet method, Centrifugal method, Chemical method, Laser method and Plasma method.

  1. Requirements for enrichment tools

    NARCIS (Netherlands)

    Boer, A.; Winkels, R.; Trompper, M.

    2016-01-01

    This report gives a high level overview of requirements for Enrichment tools in the Openlaws.eu project. Openlaws.eu aims to initiate a platform and develop a vision for Big Open Legal Data (BOLD): an open framework for legislation, case law, and legal literature from across Europe.

  2. Enriching the Catalog

    Science.gov (United States)

    Tennant, Roy

    2004-01-01

    After decades of costly and time-consuming effort, nearly all libraries have completed the retrospective conversion of their card catalogs to electronic form. However, bibliographic systems still are really not much more than card catalogs on wheels. Enriched content that Amazon.com takes for granted--such as digitized tables of contents, cover…

  3. SMART core preliminary nuclear design-II

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Chan; Ji, Seong Kyun; Chang, Moon Hee

    1997-06-01

    Three loading patterns for 330 MWth SMART core are constructed for 25, 33 and 29 CRDMs, and one loading pattern for larger 69-FA core with 45 CRDMs is also constructed for comparison purpose. In this study, the core consists of 57 reduced height Korean Optimized Fuel Assemblies (KOFAs) developed by KAERI. The enrichment of fuel is 4.95 w/o. As a main burnable poison, 35% B-10 enriched B{sub 4}C-Al{sub 2}O{sub 3} shim is used. To control stuck rod worth, some gadolinia bearing fuel rods are used. The U-235 enrichment of the gadolinia bearing fuel rods is 1.8 w/o as used in KOFA. All patterns return cycle length of about 3 years. Three loading patterns except 25-CRDM pattern satisfy cold shutdown condition of keff {<=} 0.99 without soluble boron. These three patterns also satisfy the refueling condition of keff {<=} 0.95. In addition to the construction of loading pattern, an editing module of MASTER PPI files for rod power history generation is developed and rod power histories are generated for 29-CRDM loading pattern. Preliminary Fq design limit is suggested as 3.71 based on KOFA design experience. (author). 9 tabs., 45 figs., 16 refs.

  4. Availability of enrichment services

    International Nuclear Information System (INIS)

    Svenke, E.

    1977-01-01

    The report summarizes major uncertainties which are likely to influence future demands for uranium isotopic enrichment. Since for the next decade the development of nuclear power will be largely concerned with the increment in demand the timely need for enrichment capacity will be particularly sensitive to assumptions about growth rates. Existing worldwide capacity together with capacities under construction will be sufficient well into the 1980's. However, long decision and construction leadtime, uncertainty as to future demand as well as other factors, specifically high capital need, all of which entail financial risks, create hindrances to a timely development of increment. The adequacy of current technology is well demonstrated in plant operation and new technology is under way. Technology is, however, not freely available on a purely commercial basis. Commercial willingness, which anticipates a limited degree of financial risk, is requesting both long term back-up from the utilities that would parallel their firm decisions on the acquisition of nuclear power units, and a protective government umbrella. This situation depends on the symbiotic relationship that exists between the nuclear power generating organizations, the enrichment undertakings and the governments involved. The report accordingly stresses the need for a more cooperative approach and this, moreover, at the multinational level. There is otherwise a risk that proper resources and financing means will not be allocated to the enrichment sector. Export limitations that request the highest degree of industrial processing of nuclear fuel, i.e. the compulsory enrichment of natural uranium, do not serve the interests of overall industrial efficiency

  5. Promotion of uranium enrichment business

    International Nuclear Information System (INIS)

    Kurushima, Morihiro

    1981-01-01

    The Committee on Nuclear Power has studied on the basic nuclear power policy, establishing its five subcommittees, entrusted by the Ministry of Nternational Trade and Industry. The results of examination by the subcommittee on uranium enrichment business are given along with a report in this connection by the Committee. In order to establish the nuclear fuel cycle, the aspect of uranium enrichment is essential. The uranium enrichment by centrifugal process has proceeded steadily in Power Reactor and Nuclear Fuel Development Corporation. The following matters are described: the need for domestic uranium enrichment, the outlook for overseas enrichment services and the schedule for establishing domestic enrichment business, the current state of technology development, the position of the prototype enrichment plant, the course to be taken to establish enrichment business the main organization operating the prototype and commercial plants, the system of supplying centrifuges, the domestic conversion of natural uranium the subsidies for uranium enrichment business. (J.P.N.)

  6. United States uranium enrichment policies

    International Nuclear Information System (INIS)

    Roberts, R.W.

    1977-01-01

    ERDA's uranium enrichment program policies governing the manner in which ERDA's enrichment complex is being operated and expanded to meet customer requirements for separative work, research and development activities directed at providing technology alternatives for future enrichment capacity, and establishing the framework for additional domestic uranium enrichment capacity to meet the domestic and foreign nuclear industry's growing demand for enrichment services are considered. The ERDA enrichment complex consists of three gaseous diffusion plants located in Oak Ridge, Tennessee; Paducah, Kentucky; and Portsmouth, Ohio. Today, these plants provide uranium enrichment services for commercial nuclear power generation. These enrichment services are provided under contracts between the Government and the utility customers. ERDA's program involves a major pilot plant cascade, and pursues an advanced isotope separation technique for the late 1980's. That the United States must develop additional domestic uranium enrichment capacity is discussed

  7. Future of uranium enrichment

    International Nuclear Information System (INIS)

    Hosmer, C.

    1981-01-01

    The increasing amount of separative work being done in government facilities to produce low-enriched uranium fuel for nuclear utilities again raises the question: should this business-type, industrial function be burned over the private industry. The idea is being looked at by the Reagan administration, but faces problems of national security as well as from the unique nature of the business. This article suggests that a joint government-private venture combining enriching, reprocessing, and waste disposal could be the answer. Further, a separate entity using advanced laser technology to deplete existing uranium tails and lease them for fertile blankets in breeder reactors might earn substantial revenues to help reduce the national debt

  8. South Australia, uranium enrichment

    International Nuclear Information System (INIS)

    1976-02-01

    The Report sets out the salient data relating to the establishment of a uranium processing centre at Redcliff in South Australia. It is conceived as a major development project for the Commonwealth, the South Australian Government and Australian Industry comprising the refining and enrichment of uranium produced from Australian mines. Using the data currently available in respect of markets, demand, technology and possible financial return from overseas sales, the project could be initiated immediately with hexafluoride production, followed rapidly in stages by enrichment production using the centrifuge process. A conceptual development plan is presented, involving a growth pattern that would be closely synchronised with the mining and production of yellowcake. The proposed development is presented in the form of an eight-and-half-year programme. Costs in this Report are based on 1975 values, unless otherwise stated. (Author)

  9. Beta activity of enriched uranium

    International Nuclear Information System (INIS)

    Nambiar, P.P.V.J.; Ramachandran, V.

    1975-01-01

    Use of enriched uranium as reactor fuel necessitates its handling in various forms. For purposes of planning and organising radiation protection measures in enriched uranium handling facilities, it is necessary to have a basic knowledge of the radiation status of enriched uranium systems. The theoretical variations in beta activity and energy with U 235 enrichment are presented. Depletion is considered separately. Beta activity build up is also studied for two specific enrichments, in respect of which experimental values for specific alpha activity are available. (author)

  10. Local power peaking factor estimation in nuclear fuel by artificial neural networks

    International Nuclear Information System (INIS)

    Montes, Jose Luis; Francois, Juan Luis; Ortiz, Juan Jose; Martin-del-Campo, Cecilia; Perusquia, Raul

    2009-01-01

    This paper presents the training of an artificial neural network (ANN) to accurately predict, in very short time, a physical parameter used in nuclear fuel reactor optimization: the local power peaking factor (LPPF) in a typical boiling water reactor (BWR) fuel lattice. The ANN training patterns are distribution of fissile and burnable poison materials in the fuel lattice and their associated LPPF. These data were obtained by modeling the fuel lattices with a neutronic simulator: the HELIOS transport code. The combination of the pin U 235 enrichment and the Gd 2 O 3 (gadolinia) concentration, inside the 10 x 10 fuel lattice array, was encoded by three different methods. However, the only encoding method that was able to give a good prediction of the LPPF was the method which added the U 235 enrichment and the gadolinia concentration. The results show that the relative error in the estimation of the LPPF, obtained by the trained ANN, ranged from 0.022% to 0.045%, with respect to the HELIOS results

  11. Blueprint for domestic uranium enrichment

    International Nuclear Information System (INIS)

    1981-01-01

    The AEC advisory committee on domestic production of uranium enrichment has studied for more than a year how to achieve the domestic enrichment of uranium by the construction and operation of a commercial enriching plant using centrifugal separation method, and the report was submitted to the Atomic Energy Commission on August 18, 1980. Japan has depended wholly on overseas services for her uranium enrichment needs, but the development of domestic enrichment has been carried on in parallel. The AEC decided to construct a uranium enrichment pilot plant using centrifuges, and it has been forwarded as a national project. The plant is operated by the Power Reactor and Nuclear Fuel Development Corp. since 1979. The capacity of the plant will be raised to approximately 75 ton SWU a year. The centrifuges already operated have provided the first delivery of fuel of about 1 ton for the ATR ''Fugen''. The demand-supply balance of uranium enrichment service, the significance of the domestic enrichment of uranium, the evaluation of uranium enrichment technology, the target for domestic enrichment plan, the measures to promote domestic uranium enrichment, and the promotion of the construction of a demonstration plant are reported. (Kako, I.)

  12. Uranium enrichment by gas centrifuge

    International Nuclear Information System (INIS)

    Heriot, I.D.

    1988-01-01

    After recalling the physical principles and the techniques of centrifuge enrichment the report describes the centrifuge enrichment programmes of the various countries concerned and compares this technology with other enrichment technologies like gaseous diffusion, laser, aerodynamic devices and chemical processes. The centrifuge enrichment process is said to be able to replace with advantage the existing enrichment facilities in the short and medium term. Future prospects of the process are also described, like recycled uranium enrichment and economic improvements; research and development needs to achieve the economic prospects are also indicated. Finally the report takes note of the positive aspect of centrifuge enrichment as far as safeguards and nuclear safety are concerned. 27 figs, 113 refs

  13. Radiometric enrichment of nonradioactive ores

    International Nuclear Information System (INIS)

    Mokrousov, V.A.; Lileev, V.A.

    1979-01-01

    Considered are the methods of mineral enrichment based on the use of the radioation of various types. The physical essence of enrichment processes is presented, their classification is given. Described are the ore properties influencing the efficiency of radiometric enrichment, methods of the properties study and estimation of ore enrichment. New possibilities opened by radiometric enrichment in the technology of primary processing of mineral raw materials are elucidated. A considerable attention is paid to the main and auxiliary equipment for radiometric enrichment. The foundations of the safety engineering are presented in a brief form. Presented are also results of investigations and practical works in the field of enrichment of ores of non-ferrous, ferrous and non-metallic minerals with the help of radiometric methods

  14. Design and analysis challenges for advanced nuclear fuel

    International Nuclear Information System (INIS)

    Klepfer, H.; Abdollahian, D.; Dias, A.; Durston, C.; Eisenhart, L.; Engel, R.; Gilmore, P.; Rank, P.; Kjaer-Pedersen, N.; Sorensen, J.; Yang, R.; Agee, L.

    2004-01-01

    Significant changes have been incorporated in the light water reactor (LWR) fuel designs now being offered, and advanced fuel designs are currently being developed for the existing and the next generation of reactor designs. These advanced fuel design configurations are intended to offer utilities major economic gains, including: (1) improved fuel characteristics through optimized hydrogen to uranium ratio within the core; (2) increased capacity factor by allowing longer operating cycles, which is implemented by increasing the fuel enrichment and the amount and distribution of burnable poison, gadolinia, boron, or erbium within the fuel assembly to achieve higher discharge burnup; and (3) increased plant power output, if it can be accommodated by the balance of plant, by increasing the power density of the fuel assembly. The authors report here work being done to identify emerging technical issues in support of utility industry evaluations of advanced fuel designs. (author)

  15. THE INFLUENCE OF CaO AND P2O5 OF BONE ASH UPON THE REACTIVITY AND THE BURNABILITY OF CEMENT RAW MIXTURES

    Directory of Open Access Journals (Sweden)

    TOMÁŠ IFKA

    2012-03-01

    Full Text Available The influence of CaO and P2O5 upon the reactivity of cement raw meal was investigated in this paper. Ash of bone meal containing Ca3(PO42 - 3CaO·P2O5 was used as the source of P2O5. Two series of samples with different content of the ash of bone meal were prepared. In the first series, the ash of bone was added into cement raw meal. The second series of samples were prepared by considering ash as one of CaO sources. Therefore, the total content of CaO in cement raw meal was kept constant, while the amount of P2O5 increased. These different series of samples were investigated by analyzing free lime content in the clinkers. The XRD analysis and Electron Micro Probe Analyzer analysis of the clinkers were also carried out. Two parameters were used to characterize the reactivity of cement raw meal: content of free lime and Burnability Index (BI calculated from free lime content in both series of samples burnt at 1350 ºC, 1400 ºC, 1450 ºC and 1500 ºC. According to the first parameter, P2O5 content that drastically makes worse the reactivity of cement raw meal was found at 1.11 wt.% in the first series, while this limit has reached 1.52 wt.% in the second one. According to the BI, the limit of P2O5 was found at 1.42 wt. % in the first series and 1, 61 wt.% in the second one. Furthermore, EPMA has demonstrated the presence of P2O5 in both calcium silicate phases forming thus solid solutions.

  16. The world enrichment market

    International Nuclear Information System (INIS)

    Gunter, L.; McCants, C.; Rutkowski, E.

    1991-01-01

    The enrichment market can be divided into two periods: the near-term market (1991 to 1995) and the long-term market (1995 and beyond). The near-term market is characterized by limited unfilled requirements of 4% per year, to be supplied by national stockpiles and excess inventories. This low-cost material will be drawn down by about 1993, causing a subsequent price rise. As the price rises, primary supplier activity is expected to increase. In the near-term, two contracting activities are apparent: spot; and intermediate-term. The current spot market is expected to last until available low cost inventories are drawn down. Recently, in attempts to gain market share, suppliers have offered attractively priced intermediate-term (3 year) contracts for 1996 to 1998. While a small spot market will continue after 1995, it is anticipated that utilities will prefer a mix of medium- and long-term (5 to 10 year) contracts from primary suppliers for most of their enrichment requirements. As national stockpiles and utility inventories are consumed, low-cost supply available to the spot market is expected to diminish. Consequently, with little low-cost supply available, the only apparent source of material will be from primary suppliers, and the resulting competition over market share is expected to be intense. (author)

  17. Motif enrichment tool.

    Science.gov (United States)

    Blatti, Charles; Sinha, Saurabh

    2014-07-01

    The Motif Enrichment Tool (MET) provides an online interface that enables users to find major transcriptional regulators of their gene sets of interest. MET searches the appropriate regulatory region around each gene and identifies which transcription factor DNA-binding specificities (motifs) are statistically overrepresented. Motif enrichment analysis is currently available for many metazoan species including human, mouse, fruit fly, planaria and flowering plants. MET also leverages high-throughput experimental data such as ChIP-seq and DNase-seq from ENCODE and ModENCODE to identify the regulatory targets of a transcription factor with greater precision. The results from MET are produced in real time and are linked to a genome browser for easy follow-up analysis. Use of the web tool is free and open to all, and there is no login requirement. ADDRESS: http://veda.cs.uiuc.edu/MET/. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

  18. Modular enrichment measurement system for in-situ enrichment assay

    International Nuclear Information System (INIS)

    Stewart, J.P.

    1976-01-01

    A modular enrichment measurement system has been designed and is in operation within General Electric's Nuclear Fuel Fabrication Facility for the in-situ enrichment assay of uranium-bearing materials in process containers. This enrichment assay system, which is based on the ''enrichment meter'' concept, is an integral part of the site's enrichment control program and is used in the in-situ assay of the enrichment of uranium dioxide (UO 2 ) powder in process containers (five gallon pails). The assay system utilizes a commercially available modular counting system and a collimnator designed for compatability with process container transport lines and ease of operator access. The system has been upgraded to include a microprocessor-based controller to perform system operation functions and to provide data acquisition and processing functions. Standards have been fabricated and qualified for the enrichment assay of several types of uranium-bearing materials, including UO 2 powders. The assay system has performed in excess of 20,000 enrichment verification measurements annually and has significantly contributed to the facility's enrichment control program

  19. Enrichment of boron 10

    International Nuclear Information System (INIS)

    Coutinho, C.M.M.; Rodrigues Filho, J.S.R.; Umeda, K.; Echternacht, M.V.

    1990-01-01

    A isotopic separation pilot plant with five ion exchange columns interconnected in series were designed and built in the IEN. The columns are charged with a strong anionic resin in its alkaline form. The boric acid solution is introduced in the separation columns until it reaches a absorbing zone length which is sufficient to obtain the desired boron-10 isotopic concentration. The boric acid absorbing zone movement is provided by the injection of a diluted hydrochloric acid solution, which replace the boric acid throughout the columns. The absorbing zone equilibrium length is proportional to its total length. The enriched boron-10 and the depleted boron are located in the final boundary and in the initial position of the absorbing zones, respectively. (author)

  20. Thermal breeder fuel enrichment zoning

    International Nuclear Information System (INIS)

    Capossela, H.J.; Dwyer, J.R.; Luce, R.G.; McCoy, D.F.; Merriman, F.C.

    1992-01-01

    A method and apparatus for improving the performance of a thermal breeder reactor having regions of higher than average moderator concentration are disclosed. The fuel modules of the reactor core contain at least two different types of fuel elements, a high enrichment fuel element and a low enrichment fuel element. The two types of fuel elements are arranged in the fuel module with the low enrichment fuel elements located between the high moderator regions and the high enrichment fuel elements. Preferably, shim rods made of a fertile material are provided in selective regions for controlling the reactivity of the reactor by movement of the shim rods into and out of the reactor core. The moderation of neutrons adjacent the high enrichment fuel elements is preferably minimized as by reducing the spacing of the high enrichment fuel elements and/or using a moderator having a reduced moderating effect. 1 figure

  1. Advanced Neutron Source enrichment study

    International Nuclear Information System (INIS)

    Bari, R.A.; Ludewig, H.; Weeks, J.R.

    1996-01-01

    A study has been performed of the impact on performance of using low-enriched uranium (20% 235 U) or medium-enriched uranium (35% 235 U) as an alternative fuel for the Advanced Neutron Source, which was initially designed to use uranium enriched to 93% 235 U. Higher fuel densities and larger volume cores were evaluated at the lower enrichments in terms of impact on neutron flux, safety, safeguards, technical feasibility, and cost. The feasibility of fabricating uranium silicide fuel at increasing material density was specifically addressed by a panel of international experts on research reactor fuels. The most viable alternative designs for the reactor at lower enrichments were identified and discussed. Several sensitivity analyses were performed to gain an understanding of the performance of the reactor at parametric values of power, fuel density, core volume, and enrichment that were interpolations between the boundary values imposed on the study or extrapolations from known technology

  2. Enrichment plants. A survey of major new uranium enriching projects

    International Nuclear Information System (INIS)

    Kovan, D.

    1976-01-01

    The work enrichment situation is reported. The development of enrichment in the U.S. and in Europe is outlined. A brief description is given of the technology of separation by diffusion and by centrifugation and the advantages and disadvantages of the two processes are compared. Finally the supply and demand situation is briefly considered. (U.K.)

  3. Conversion of highly enriched uranium in thorium-232 based oxide fuel for light water reactors: MOX-T fuel

    Energy Technology Data Exchange (ETDEWEB)

    Vapirev, E I; Jordanov, T; Christoskov, I [Sofia Univ. (Bulgaria). Fizicheski Fakultet

    1994-12-31

    The idea of conversion of highly enriched uranium (HEU) from warheads without mixing it with natural uranium as well as the utilization of plutonium as fuel component is discussed. A nuclear fuel which is a mixture of 4% {sup 235}U (HEU) as a fissile isotope and 96 % {sup 232}Th (ThO{sub 2}) as a non-fissile isotope in a mixed oxide with thorium fuel is proposed. It is assumed that plutonium can also be used in the proposed fuel in a mixture with {sup 235}U. The following advantages of the use of HEU in LWRs in mixed {sup 235}U - Th fuel are pointed out: (1) No generation of long-living plutonium and americium isotopes (in case of reprocessing the high level radioactive wastes will contain only fission fragments and uranium); (2) The high conversion ratio of Th extends the expected burnup by approximately 1/3 without higher initial enrichment (the same initial enrichment simplifies the problem for compensation of the excess reactivity in the beginning with burnable poison and boric acid); (3) The high conversion ratio of Th allows the fuel utilization with less initial enrichment (by approx. 1/3) for the same burnup; thus less excess reactivity has to be compensated after reloading; in case of fuel reprocessing all fissile materials ({sup 235}U + {sup 233}U) could be chemically extracted. Irrespectively to the optimistic expectations outlined, further work including data on optimal loading and reloading schemes, theoretical calculations of thermal properties of {sup 235}U + Th fuel rods, manufacturing of several test fuel assemblies and investigations of their operational behaviour in a reactor core is still needed. 1 fig., 7 refs.

  4. Industrial aspects in uranium enrichment

    International Nuclear Information System (INIS)

    Mezin, M.

    1982-05-01

    Characteristics of isotope separation processes in operation and under development are discussed. These include the number of stages in series, the number of components, the component unit capacity and enery requirements. The implementation of an enrichment process and the question of an enrichment plant in Australia are also considered

  5. City model enrichment

    Science.gov (United States)

    Smart, Philip D.; Quinn, Jonathan A.; Jones, Christopher B.

    The combination of mobile communication technology with location and orientation aware digital cameras has introduced increasing interest in the exploitation of 3D city models for applications such as augmented reality and automated image captioning. The effectiveness of such applications is, at present, severely limited by the often poor quality of semantic annotation of the 3D models. In this paper, we show how freely available sources of georeferenced Web 2.0 information can be used for automated enrichment of 3D city models. Point referenced names of prominent buildings and landmarks mined from Wikipedia articles and from the OpenStreetMaps digital map and Geonames gazetteer have been matched to the 2D ground plan geometry of a 3D city model. In order to address the ambiguities that arise in the associations between these sources and the city model, we present procedures to merge potentially related buildings and implement fuzzy matching between reference points and building polygons. An experimental evaluation demonstrates the effectiveness of the presented methods.

  6. AEC determines uranium enrichment policy

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    The Advisory Committee on Uranium Enrichment of the Atomic Energy Commission (AEC) has submitted a report to AEC chairman concerning the promotion of the introduction of advanced material, high performance centrifuges to replace conventional metallic drum centrifuges, and the development of next generation advanced centrifuges. The report also called for the postponement until around 1997 of the decision whether the development should be continued or not on atomic vapor laser isotope separation (AVLIS) and molecular laser isotope separation (MLIS) processes, as well as the virtual freezing of the construction of a chemical process demonstration plant. The report was approved by the AEC chairman in August. The uranium enrichment service market in the world will continue to be characterized by oversupply. The domestic situation of uranium enrichment supply-demand trend, progress of the expansion of Rokkasho enrichment plant, the trend in the development of gas centrifuge process and the basic philosophy of commercializing domestic uranium enrichment are reported. (K.I.)

  7. New generation enrichment monitoring technology for gas centrifuge enrichment plants

    International Nuclear Information System (INIS)

    Ianakiev, Kiril D.; Alexandrov, Boian S.; Boyer, Brian D.; Hill, Thomas R.; Macarthur, Duncan W.; Marks, Thomas; Moss, Calvin E.; Sheppard, Gregory A.; Swinhoe, Martyn T.

    2008-01-01

    The continuous enrichment monitor, developed and fielded in the 1990s by the International Atomic Energy Agency, provided a go-no-go capability to distinguish between UF 6 containing low enriched (approximately 4% 235 U) and highly enriched (above 20% 235 U) uranium. This instrument used the 22-keV line from a 109 Cd source as a transmission source to achieve a high sensitivity to the UF 6 gas absorption. The 1.27-yr half-life required that the source be periodically replaced and the instrument recalibrated. The instrument's functionality and accuracy were limited by the fact that measured gas density and gas pressure were treated as confidential facility information. The modern safeguarding of a gas centrifuge enrichment plant producing low-enriched UF 6 product aims toward a more quantitative flow and enrichment monitoring concept that sets new standards for accuracy stability, and confidence. An instrument must be accurate enough to detect the diversion of a significant quantity of material, have virtually zero false alarms, and protect the operator's proprietary process information. We discuss a new concept for advanced gas enrichment assay measurement technology. This design concept eliminates the need for the periodic replacement of a radioactive source as well as the need for maintenance by experts. Some initial experimental results will be presented.

  8. The slightly-enriched spectral shift control reactor. Final report, September 30, 1988--September 30, 1991

    Energy Technology Data Exchange (ETDEWEB)

    Martin, W.R.; Lee, J.C.; Larsen, E.W. [Michigan Univ., Ann Arbor, MI (United States). Dept. of Nuclear Engineering; Edlund, M.C. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Mechanical and Nuclear Engineering

    1991-11-01

    An advanced converter reactor design utilizing mechanical spectral shift control rods in a conventional pressurized water reactor configuration is under investigation. The design is based on the principle that a harder spectrum during the early part of the fuel cycle will result in large neutron captures in fertile {sup 238}U, which can then be burned in situ in a softer spectrum later in the cycle. Preliminary design calculations performed during FY 89 showed that the slightly-enriched spectral shift reactor design offers the benefit of substantially increased fuel resource utilization with the proven safety characteristics of the pressurized water reactor technology retained. Optimization of the fuel design and development of fuel management strategies were carried out in FY 90, along with effort to develop and validate neutronic methodology for tight-lattice configurations with hard spectra. During FY 91, the final year of the grant, the final Slightly-Enriched Spectral Shift Reactor (SESSR) design was determined, and reference design analyses were performed for the assemblies as well as the global core configuration, both at the beginning of cycle (BOC) and with depletion. The final SESSR design results in approximately a 20% increase in the utilization of uranium resources, based on equilibrium fuel cycle analyses. Acceptable pin power peaking is obtained with the final core design, with assembly peaking factors equal to less than 1.04 for spectral shift control rods both inserted and withdrawn, and global peaking factors at BOC predicted to be 1.4. In addition, a negative Moderation Temperature Coefficient (MTC) is maintained for BOC, which is difficult to achieve with conventional advanced converter designs based on a closed fuel cycle. The SESSR design avoids the need for burnable poison absorber, although they could be added if desired to increase the cycle length while maintaining a negative MTC.

  9. The main conditions ensured problemless implementation of 235U high enriched fuel in Kozloduy NPP (Bulgaria) - WWER-1000 Units

    International Nuclear Information System (INIS)

    Dobrevski, I.; Zaharieva, N.; Minkova, K.; Michaylov, G.; Penev, P.; Gerchev, N.

    2009-01-01

    The collected water chemistry and radiochemistry data during the operation of the Kozloduy NPP Unit 5 for the period 2006-2009 (12-th, 13-th 14-th and 15-th fuel cycles) undoubtedly indicate for WWER-1000 Units (whose specific features are: Steam generators with austenitic stainless steel 08Cr18N10T tubing; Steam generators are with horizontal straight tubing and Fuel elements cladding material is Zr-1%Nb (Zr1Nb) alloy), that one realistic way for problemless implementation of 235 U high enriched fuel have been found. The main feature characteristics of this way are: Implementation of solid neutron burnable absorbers together with the dissolved in coolant neutron absorber - natural boric acid; Application of fuel cladding materials with enough corrosion resistance by the specific fuel cladding environment created by presence of SNB; Keeping of suitable coolant water chemistry which ensures low corrosion rates of core- and out-of-core- materials and limits in core (cladding) depositions and restricts out-of-core radioactivity buildup. The realization of this way in WWER-1000 Units in Kozloduy NPP was practically carried out through: 1) Implementation of Russian fuel assemblies TVSA which have as fuel cladding material E-110 alloy (Zr1Nb) with enough high corrosion resistance by presence of sub-cooled nucleate boiling (SNB) and use burnable absorber (Gd) integrated in the uranium-gadolinium (U-Gd 2 O 3 ) fuel (fuel rod with 5.0% Gd 2 O 3 ); 2) Development and implementation of water chemistry primary circuit guidelines, which require the relation between boric acid concentration and total alkalising agent concentrations to ensure coolant pH 300 = 7.0 - 7.2 values during the whole operation period. The above mentioned conditions by the passing of WWER-1000 Units in NPP Kozloduy to uranium fuel with 4.4% 235 U (TVSA fuel assemblies) practically ensured avoidance of the creation of the necessary conditions for AOA onset. The operational experience (2006-2009) of the

  10. Hydrogen-enriched fuels

    Energy Technology Data Exchange (ETDEWEB)

    Roser, R. [NRG Technologies, Inc., Reno, NV (United States)

    1998-08-01

    NRG Technologies, Inc. is attempting to develop hardware and infrastructure that will allow mixtures of hydrogen and conventional fuels to become viable alternatives to conventional fuels alone. This commercialization can be successful if the authors are able to achieve exhaust emission levels of less than 0.03 g/kw-hr NOx and CO; and 0.15 g/kw-hr NMHC at full engine power without the use of exhaust catalysts. The major barriers to achieving these goals are that the lean burn regimes required to meet exhaust emissions goals reduce engine output substantially and tend to exhibit higher-than-normal total hydrocarbon emissions. Also, hydrogen addition to conventional fuels increases fuel cost, and reduces both vehicle range and engine output power. Maintaining low emissions during transient driving cycles has not been demonstrated. A three year test plan has been developed to perform the investigations into the issues described above. During this initial year of funding research has progressed in the following areas: (a) a cost effective single-cylinder research platform was constructed; (b) exhaust gas speciation was performed to characterize the nature of hydrocarbon emissions from hydrogen-enriched natural gas fuels; (c) three H{sub 2}/CH{sub 4} fuel compositions were analyzed using spark timing and equivalence ratio sweeping procedures and finally; (d) a full size pick-up truck platform was converted to run on HCNG fuels. The testing performed in year one of the three year plan represents a baseline from which to assess options for overcoming the stated barriers to success.

  11. High enrichment to low enrichment core's conversion. Technical securities

    International Nuclear Information System (INIS)

    Abbate, P.; Madariaga, M.R.

    1990-01-01

    This work presents the fulfillment of the technical securities subscribed by INVAP S.E. for the conversion of a high enriched uranium core. The reactor (of 5 thermal Mw), built in the 50's and 60's, is of the 'swimming pool' type, with light water and fuel elements of the curve plates MTR type, enriched at 93.15 %. These are neutronic and thermohydraulic securities. (Author) [es

  12. Safety of uranium enrichment plant

    International Nuclear Information System (INIS)

    Yonekawa, Shigeru; Morikami, Yoshio; Morita, Minoru; Takahashi, Tsukasa; Tokuyasu, Takashi.

    1991-01-01

    With respect to safety evaluation of the gas centrifuge enrichment facility, several characteristic problems are described as follows. Criticality safety in the cascade equipments can be obtained to maintain the enrichment of UF 6 below 5 %. External radiation dose equivalent rate of the 30B cylinder is low enough, the shield is not necessary. Penetration ratio of the two-stage HEPA filters for UF 6 aerosol is estimated at 10 -9 . From the experimental investigation, vacuum tightness is not damaged by destruction of gas centrifuge rotor. Carbon steel can be used for uranium enrichment equipments under the condition below 100degC. (author)

  13. Environmental enrichment for aquatic animals.

    Science.gov (United States)

    Corcoran, Mike

    2015-05-01

    Aquatic animals are the most popular pets in the United States based on the number of owned pets. They are popular display animals and are increasingly used in research settings. Enrichment of captive animals is an important element of zoo and laboratory medicine. The importance of enrichment for aquatic animals has been slower in implementation. For a long time, there was debate over whether or not fish were able to experience pain or form long-term memories. As that debate has reduced and the consciousness of more aquatic animals is accepted, the need to discuss enrichment for these animals has increased. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. World enrichment requirements to 2005

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    The primary enrichment suppliers-Eurodif, Techsnabexport, Urenco, and the US DOE - are positioning themselves to take advantage of the post - 1995 market. Overall, unfilled requirements represent about 40 percent of world requirements in the year 2000. The USA will be the primary market, as US utilities' unfilled enrichment requirements account for over 60 percent of the world's total unfilled requirements. The enrichment market is moving toward more global competition, as each supplier tries to maintain its current regional market base and then to capture additional market share in other regions

  15. Burnable gas concentration control device

    International Nuclear Information System (INIS)

    Goto, Hiroshi; Sanada, Takahiro; Kuboniwa, Takao.

    1980-01-01

    Purpose: To provide connecting ports by doubling nitrogen gas injection pipes thereby to secure lengthiness of the device only by providing one nitrogen gas generator. Constitution: Nitrogen gas injection pipes are provided in two lines separately, and attachable and detachable connecting ports for feeding nitrogen gas connectable to a movable type nitrogen gas supply installation for the purpose of backing up the nitrogen gas generator. (Yoshihara, H.)

  16. Centar's gas centrifuge enrichment project

    International Nuclear Information System (INIS)

    Abajian, V.V.; Fishman, A.M.

    1976-01-01

    Plans for the building and operating of Centar Associates gas centrifuge uranium enrichment plant are described. Operating costs and machine manufacture are considered. Commitments with the utilities are summarised. (U.K.)

  17. Extraosseus enrichments in bone scintigraphy

    International Nuclear Information System (INIS)

    Jochens, R.; Schumacher, T.; Amthauer, H.; Wolter, M.; Stock, W.; Stroszczynski, C.; Moersler, J.P.; Eichstaedt, H.

    1996-01-01

    Extraosseus enrichments are common findings in bone scintigraphy. Main causes are artifacts by skin or cloth contamination, paravenous and subcutaneous injection. Physical examination, removal of cloths, skin cleaning or further images in differing projections lead to the correct diagnosis artefact or extraosseous enrichments. Further on, extraosseous enrichments are seen in physiological variants. In different diseases extraosseous enrichments are common, especially in urinary tract, liver and extremities. Further diagnostics, e.g. conventional radiologic procedures, sonography and CT scans, have to be performed. In individual cases side results in bone scintigraphy lead to formerly unknown diagnosis, further diagnostic procedure is influenced decisively. Own cases show for example a cerebral apoplectic insult, formerly unknown liver metastasis or metastasis in extraosseous Ewings's sarcoma. (orig.) [de

  18. Uranium enrichment: an evolving market

    International Nuclear Information System (INIS)

    Longenecker, J.; Witzel, R.

    1997-01-01

    With over half of the world uranium enrichment market uncommitted to any supplier early in the next century, competition is certain to be fierce. In the meantime the outlood remains unclear, with the market dominated by a number of developments -privatisation of the United States Enrichment Corp (USEC), increasing availability of Russian and US military inventories, the deployment of advanced technology and the closure of nuclear power plants due to deregulation. (author)

  19. Unjust enrichment in business law

    OpenAIRE

    Vydrová, Zuzana

    2016-01-01

    This thesis analyses the concept of unjust enrichment under the business law. First of all the thesis explains the term of business law. Business law is a complex of legal rules concerning the contractual relationships between entrepreneurs arising from their business activities. Business law is a comprehensive field of law which extends into many other fields of law, both private and public law. Equally the regulation of unjust enrichment within the business law expands into many other laws ...

  20. 75 FR 13314 - Duke Energy Carolinas, LLC; Notice of Consideration of Issuance of Amendments to Facility...

    Science.gov (United States)

    2010-03-19

    ... representative) to digitally sign documents and access the E-Submittal server for any proceeding in which it is... reactor cores with fuel containing lumped burnable and/or gadolinia integral absorbers does not involve a... acceptability of the CASMO-4/SIMULATE-3 code for performing reload design calculations for reactor cores...

  1. Feasibility study of chabazite absorber tube utilization in online absorption of released gaseous fission products and substitution of burnable absorber rods with chabazite absorber tubes in VVER-1000 reactor series

    International Nuclear Information System (INIS)

    Rahmani, Yashar

    2017-01-01

    Highlights: • Chabazite tubes are used for online removal of the released gaseous fission products. • The feasibility of using chabazite tubes instead of burnable absorber rods was studied. • A computational cycle was designed using the WIMSD5-B, CITATION-LDI2 and WERL codes. • In modeling fission gas release, the Weisman, Booth, Mason and T.S. models were used. • By this method, it is possible to increase cycle length and enhance heat transfer. - Abstract: As gaseous fission products, e.g. xenon and krypton have adverse effects such as reducing the rate of heat transfer in fuel rods and adding negative reactivity to the reactor core, the present manuscript was dedicated to development of a novel method for improving these defects. In the proposed method, chabazite absorber tubes were used for online removal of the released gaseous fission products from gaseous gap spaces. Moreover, in this research, feasibility of using chabazite absorber tubes instead of burnable absorber rods was examined. To perform the required modeling and calculations to successfully meet the mentioned objectives, a thermo-neutronic computational cycle was designed using the coupling of WIMSD5-B and CITATION-LDI2 codes in the neutronic section and the WERL code in the thermo-hydraulic calculations. In addition, in modeling the release process of gaseous fission products, the Weisman, Booth, Mason, and T.S. models were examined. It is worth mentioning that in this research, calculations and modeling procedures were based on the first cycle of Bushehr’s VVER-1000 reactor to study the feasibility of the proposed solution. The obtained results revealed that with application of the proposed method in this research, it is possible to increase cycle length, improve safety thresholds, and enhance heat transfer in the core of nuclear reactors.

  2. High enrichment to low enrichment core's conversion. Accidents analysis

    International Nuclear Information System (INIS)

    Abbate, P.; Rubio, R.; Doval, A.; Lovotti, O.

    1990-01-01

    This work analyzes the different accidents that may occur in the reactor's facility after the 20% high-enriched uranium core's conversion. The reactor (of 5 thermal Mw), built in the 50's and 60's, is of the 'swimming pool' type, with light water and fuel elements of the curve plates MTR type, enriched at 93.15 %. This analysis includes: a) accidents by reactivity insertion; b) accidents by coolant loss; c) analysis by flow loss and d) fission products release. (Author) [es

  3. Gaseous diffusion -- the enrichment workhorse

    International Nuclear Information System (INIS)

    Shoemaker, J.E. Jr.

    1984-01-01

    Construction of the first large-scale gaseous diffusion facility was started as part of the Manhattan Project in Oak Ridge, Tennessee, in 1943. This facility, code named ''K-25,'' began operation in January 1945 and was fully on stream by September 1945. Four additional process buildings were later added in Oak Ridge as the demand for enriched uranium escalated. New gaseous diffusion plants were constructed at Paducah, Kentucky, and Portsmouth, Ohio, during this period. The three gaseous diffusion plants were the ''workhorses'' which provided the entire enriched uranium demand for the United States during the 1950s and 1960s. As the demand for enriched uranium for military purposes decreased during the early 1960s, power to the diffusion plants was curtailed to reduce production. During the 1960s, as plans for the nuclear power industry were formulated, the role of the diffusion plants gradually changed from providing highly-enriched uranium for the military to providing low-enriched uranium for power reactors

  4. Uranium enrichment. Technology, economics, capacity

    International Nuclear Information System (INIS)

    Voigt, W.R. Jr.; Saire, D.E.; Gestson, D.K.; Peske, S.E.; Vanstrum, P.R.

    1983-01-01

    Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R+D efforts on various processes. (author)

  5. Uranium enrichment: technology, economics, capacity

    Energy Technology Data Exchange (ETDEWEB)

    Voigt, Jr., W. R.; Vanstrum, P. R.; Saire, D. E.; Gestson, D. K.; Peske, S. E.

    1982-08-01

    Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R and D efforts on various processes.

  6. Uranium enrichment: technology, economics, capacity

    International Nuclear Information System (INIS)

    Voigt, W.R. Jr.; Vanstrum, P.R.; Saire, D.E.; Gestson, D.K.; Peske, S.E.

    1982-01-01

    Large-scale enrichment of uranium has now been carried out for 40 years. While the gaseous diffusion process was the original choice of several countries and continues today to provide the major component of the world production of separative work, the last two decades have witnessed the development of a number of alternative processes for enrichment. These processes, which are being studied and deployed around the world, offer a wide range of technical and economic characteristics which will be useful in assuring adequate capacity to meet projected reactor fuel market needs through the rest of this century at competitive prices. With present uncertainties in future enriched uranium needs, it is apparent that flexibility in the deployment and operation of any enrichment process will be one of the prime considerations for the future. More economical production of separative work not only can have a beneficial impact on reactor fuel costs, but also tends to conserve natural uranium resources. This paper reviews the world scene in the enrichment component of the fuel cycle, including existing or planned commercial-scale facilities and announced R and D efforts on various processes

  7. A Systematic Approach to Marital Enrichment.

    Science.gov (United States)

    Dinkmeyer, Don; Carlson, Jon

    1986-01-01

    Presents a systematic approach to enriching marital relationships. The history and current status of marital enrichment is reviewed. An Adlerian approach to marital enrichment is described. Applications of the program in enrichment groups, marriage therapy and couple groups are included. (Author)

  8. Enrichment of light hydrocarbon mixture

    Science.gov (United States)

    Yang,; Dali, [Los Alamos, NM; Devlin, David [Santa Fe, NM; Barbero, Robert S [Santa Cruz, NM; Carrera, Martin E [Naperville, IL; Colling, Craig W [Warrenville, IL

    2010-08-10

    Light hydrocarbon enrichment is accomplished using a vertically oriented distillation column having a plurality of vertically oriented, nonselective micro/mesoporous hollow fibers. Vapor having, for example, both propylene and propane is sent upward through the distillation column in between the hollow fibers. Vapor exits neat the top of the column and is condensed to form a liquid phase that is directed back downward through the lumen of the hollow fibers. As vapor continues to ascend and liquid continues to countercurrently descend, the liquid at the bottom of the column becomes enriched in a higher boiling point, light hydrocarbon (propane, for example) and the vapor at the top becomes enriched in a lower boiling point light hydrocarbon (propylene, for example). The hollow fiber becomes wetted with liquid during the process.

  9. PC based uranium enrichment analyser

    International Nuclear Information System (INIS)

    Madan, V.K.; Gopalakrishana, K.R.; Bairi, B.R.

    1991-01-01

    It is important to measure enrichment of unirradiated nuclear fuel elements during production as a quality control measure. An IBM PC based system has recently been tested for enrichment measurements for Nuclear Fuel Complex (NFC), Hyderabad. As required by NFC, the system has ease of calibration. It is easy to switch the system from measuring enrichment of fuel elements to pellets and also automatically store the data and the results. The system uses an IBM PC plug in card to acquire data. The card incorporates programmable interval timers (8253-5). The counter/timer devices are executed by I/O mapped I/O's. A novel algorithm has been incorporated to make the system more reliable. The application software has been written in BASIC. (author). 9 refs., 1 fig

  10. Advances in uranium enrichment processes

    International Nuclear Information System (INIS)

    Rae, H.K.; Melvin, J.G.; Slater, J.B.

    1986-05-01

    Advances in gas centrifuges and development of the atomic vapour laser isotope separation process promise substantial reductions in the cost of enriched uranium. The resulting reduction in LWR fuel costs could seriously erode the economic advantage of CANDU, and in combination with LWR design improvements, shortened construction times and increased operational reliability could allow the LWR to overtake CANDU. CANDU's traditional advantages of neutron economy and high reliability may no longer be sufficient - this is the challenge. The responses include: combining neutron economy and dollar economy by optimizing CANDU for slightly enriched uranium fuel; developing cost-reducing improvements in design, manufacture and construction; and reducing the cost of heavy water. Technology is a renewable resource which must be continually applied to a product for it to remain competitive in the decades to come. Such innovation is a prerequisite to Canada increasing her share of the international market for nuclear power stations. The higher burn-up achievable with enriched fuel in CANDU can reduce the fuel cycle costs by 20 to 40 percent for a likely range of costs for yellowcake and separative work. Alternatively, some of the benefits of a higher fissile content can take the form of a cheaper reactor core containing fewer fuel channels and less heavy water, and needing only a single fuelling machine. An opportunity that is linked to this need to introduce an enriched uranium fuel cycle into CANDU is to build an enrichment business in Canada. This could offer greater value added to our uranium exports, security of supply for enriched CANDUs, technological growth in Canada and new employment opportunities. AECL has a study in progress to define this opportunity

  11. Uranium enriched granites in Sweden

    International Nuclear Information System (INIS)

    Wilson, M.R.; Aakerblom, G.

    1980-01-01

    Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by (1) the anatexis of continental crust (2) processes occurring at a much greater depth. They commonly show enrichement in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (Authors)

  12. Uranium enrichment. 1980 annual report

    International Nuclear Information System (INIS)

    1981-05-01

    This report contains data and related information on the production of enriched uranium at the gaseous diffusion plants and an update on the construction and project control center for the gas centrifuge plant. Power usage at the gaseous diffusion plants is illustrated. The report contains several glossy color pictures of the plants and processes described. In addition to gaseous diffusion and the centrifuge process, three advanced isotope separation process are now being developed. The business operation of the enrichment plants is described; charts on revenue, balance sheets, and income statements are included

  13. Prospects and problems of uranium enrichment

    International Nuclear Information System (INIS)

    Imai, Ryukichi

    1974-01-01

    The problem of uranium enrichment now concerns principally peaceful nuclear power generation. With the current oil crisis, energy resources assume unprecedented importance. However, the requirements for enriched uranium vary with the vicissitude of the world situation in nuclear power generation; the enterprise of uranium enrichment is related to economic aspect. The following matters are described: dimension of enrichment problem, political factors, changes in requirements, projects in each country, and strategy of enrichment in Japan. (Mori, K.)

  14. Uranium enrichment in the United States

    International Nuclear Information System (INIS)

    Hill, J.H.; Parks, J.W.

    1975-01-01

    History, improvement programs, status of electrical power availability, demands for uranium enrichment, operating plan for the U. S. enriching facilities, working inventory of enriched uranium, possible factors affecting deviations in the operating plan, status of gaseous diffusion technology, status of U. S. gas centrifuge advances, transfer of enrichment technology, gaseous diffusion--gas centrifuge comparison, new enrichment capacity, U. S. separative work pricing, and investment in nuclear energy are discussed. (LK)

  15. Enriched uranium recovery flowsheet improvements

    International Nuclear Information System (INIS)

    Holt, D.L.

    1986-01-01

    Savannah River uses 7.5% TBP to recover and purify enriched uranium. Adequate decontamination from fission products is necessary to reduce personnel exposure and to ensure that the enriched uranium product meets specifications. Initial decontamination of the enriched uranium from the fission products is carried out in the 1A bank, 16 stages of mixer-settlers. Separation of the enriched uranium from the fission product, 95 Zr, has been adequate, but excessive solvent degradation caused by the long phase contact times in the mixer-settlers has limited the 95 Zr decontamination factor (DF). An experimental program is investigating the replacement of the current 1A bank with either centrifugal contactors or a combination of centrifugal contactors and mixer-settlers. Experimental work completed has compared laboratory-scale centrifugal contactors and mixer-settlers for 95 Zr removal efficiencies. Feed solutions spiked with actual plant solutions were used. The 95 Zr DF was significantly better in the mixer-settlers than in the centrifugal contactors. As a result of this experimental study, a hybrid equipment flowsheet has been proposed for plant use. The hybrid equipment flowsheet combines the advantages of both types of solvent extraction equipment. Centrifugal contactors would be utilized in the extraction and initial scrub sections, followed by additional scrub stages of mixer-settlers

  16. Enrichment plant management and safeguards

    International Nuclear Information System (INIS)

    Hurt, N.H.

    1978-01-01

    The next increment of enrichment at Portsmouth will be gas centrifuge. The safeguards program at Portsmouth is discussed, including the DYMCAS system, the computerization, and the detectors. Control of the material access areas is discussed. The licensee material surveillance and verification program is also described

  17. The changing face of enrichment

    International Nuclear Information System (INIS)

    Dunckel, E.

    1981-01-01

    The AIS techniques considered are atomic vapour laser isotope separation, molecular laser isotope separation and plasma separation. The future of the AIS technique and their advantages over the gas centrifuge method are discussed in terms of economics, power consideration, and possible enrichment contracts. (U.K.)

  18. Environmental Development Plan: uranium enrichment

    International Nuclear Information System (INIS)

    1979-09-01

    This Environmental Development Plan identifies and examines the environmental, health, safety, and socioeconomic concerns and corresponding requirements associated with the DOE research, development, demonstration, and operation of the Uranium Enrichment program, including the gaseous diffusion process, the centrifuge process, centrifuge rotor fabrication, and related research and development activities

  19. Heterogeneous neutron absorbers development

    International Nuclear Information System (INIS)

    Boccaccini, Aldo; Agueda, Horacio; Russo, Diego; Perez, Edmundo

    1987-01-01

    The use of solid burnable absorber materials in power light water reactors has increased in the last years, specially due to improvements attained in costs of generated electricity. The present work summarizes the basic studies made on an alumina-gadolinia system, where alumina is the inert matrix and gadolinia acts as burnable poison, and describes the fabrication method of pellets with that material. High density compacts were obtained in the range of concentrations used by cold pressing and sintering at 1600 deg C in inert (Ar) atmosphere. Finally, the results of the irradiation experiences made at RA-6 reactor, located at the Bariloche Atomic Center, are given where variations on negative reactivity caused by introduction of burnable poison rods were measured. The results obtained from these experiences are in good agreement with those coming from calculation codes. (Author)

  20. Optimization of enrichment distributions in nuclear fuel assemblies loaded with Uranium and Plutonium via a modified linear programming technique

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas Vivas, Gabriel Francisco

    1999-12-01

    A methodology to optimize enrichment distributions in Light Water Reactor (LWR) fuel assemblies is developed and tested. The optimization technique employed is the linear programming revised simplex method, and the fuel assembly's performance is evaluated with a neutron transport code that is also utilized in the calculation of sensitivity coefficients. The enrichment distribution optimization procedure begins from a single-value (flat) enrichment distribution until a target, maximum local power peaking factor, is achieved. The optimum rod enrichment distribution, with 1.00 for the maximum local power peaking factor and with each rod having its own enrichment, is calculated at an intermediate stage of the analysis. Later, the best locations and values for a reduced number of rod enrichments is obtained as a function of a target maximum local power peaking factor by applying sensitivity to change techniques. Finally, a shuffling process that assigns individual rod enrichments among the enrichment groups is performed. The relative rod power distribution is then slightly modified and the rod grouping redefined until the optimum configuration is attained. To verify the accuracy of the relative rod power distribution, a full computation with the neutron transport code using the optimum enrichment distribution is carried out. The results are compared and tested for assembly designs loaded with fresh Low Enriched Uranium (LEU) and plutonium Mixed Oxide (MOX) isotopics for both reactor-grade and weapons-grade plutonium were utilized to demonstrate the wide range of applicability of the optimization technique. The feature of the assembly designs used for evaluation purposes included burnable absorbers and internal water regions, and were prepared to resemble the configurations of modern assemblies utilized in commercial Boiling Water Reactor (BWRs) and Pressurized Water Reactors (PWRs). In some cases, a net improvement in the relative rod power distribution or in the

  1. The commercial role for centrifuge enrichment

    International Nuclear Information System (INIS)

    Readle, P.H.; Wilcox, P.

    1987-01-01

    The enrichment market is extremely competitive and capacity greatly exceeds demand. BNFL [British Nuclear Fuels Ltd.] is in a unique position in having commercial experience of the two enrichment technologies currently used industrially: diffusion, and centrifuge enrichment through its associate company Urenco. In addition, BNFL is developing laser enrichment techniques as part of a UK development programme. The paper describes the enrichment market, briefly discusses the relative merits of the various methods of uranium enrichment and concludes that the gas centrifuge will be best able to respond to market needs for at least the remainder of the century. (author)

  2. Enrichment into the 21st century

    International Nuclear Information System (INIS)

    Rutkowski, E.

    1995-01-01

    This article discusses the future of the enrichment services market into the next century. It is estimated that demand for enrichment services will reach 31 million SWU by the end of the century and remain constant for the following 10 years. The current world enrichment capacity is 44 million SWU, or some 50% ahead of the demand. This oversupply is projected to continue into the next century, but in spite of this, several suppliers are planning new enrichment facilities. HEU as a source of enriched uranium is examined. Overall, long-term prices for enrichment services are expected to decline in the coming decade

  3. Enrichment demand boosts SWU prices

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    The enrichment market is picking up significantly on very brisk demand. US utilities, which normally purchase material nine months to a year ahead of time, are already hitting the market to fill their 1996 requirements. In June, two non-US utilities, one European entity and a US utility bought SWUs, the entity in an off-market deal. But that doesn't tell the whole story. Three other US utilities entered the market during the month. Meanwhile, we count 13 more utilities getting ready to hit the market for more than 4 million SWUs. Why the surge in demand? Utilities, uncertain of the role to be played by the new US Enrichment Corp. and seeking to take advantage of low interest rates, are implementing buy and hold strategies. As a result, the upper end of NUKEM's SWU price range inched up to $78. The lower end dipped to $67 based on the European deal

  4. Enrichment techniques employed in phosphoproteomics

    Czech Academy of Sciences Publication Activity Database

    Fíla, Jan; Honys, David

    2012-01-01

    Roč. 43, č. 3 (2012), s. 1025-1047 ISSN 0939-4451 R&D Projects: GA ČR(CZ) GAP501/11/1462; GA ČR GA522/09/0858; GA ČR GA525/09/0994; GA MŠk OC08011 Institutional research plan: CEZ:AV0Z50380511 Keywords : Phosphoproteomics * Enrichment * IMAC Subject RIV: ED - Physiology Impact factor: 3.914, year: 2012

  5. Uranium enrichment plans and policies

    International Nuclear Information System (INIS)

    Schwennesen, J.L.

    1981-01-01

    Significant progress has been made in US efforts to expand its enrichment capacity. The Cascade Improvement Program (CIP) and Cascade Upgrading Program (CUP) are now complete at Oak Ridge and Paducah and almost complete at Portsmouth. Considerable progress has also been made in constructing the Gas Centrifuge Enrichment Plant (GCEP), and physical construction of the first process building is well under way. Current plans are to have two process buildings on-line by 1989 with the remaining six buildings to be added sequentially as needed to meet demand. The status of DOE enrichment services contracts is essentially unchanged from that reported at last year's seminar. The OUEA latest forecast of nuclear power growth, however, is considerably lower than reported last year, although a leveling trend is becoming apparent. The Variable Tails Assay Option (VTAO) of the AFC contract was made available for the third time for FY 1983. The DOE inventories of natural uranium still remain high. The Department of Energy will dispose of this material by using it for Government programs and for enrichment plant operations. It appears that Government inventories of uranium are adequate through at least the mid-1990s. It remains DOE policy not to dispose of its natural uranium stocks through direct sales in the marketplace, except for very small quantities or if an emergency situation would exist and all reasonable attempts had been made, without success, to obtain natural uranium from commercial sources. Finally, with regard to DOE plans on future transaction tails assays, it still appears likely that the current 0.20 percent uranium-235 reference tails assay will be maintained until well into the 1990s, at which time it might be increased up to 0.25 percent uranium-235

  6. Selenium Enrichment of Horticultural Crops.

    Science.gov (United States)

    Puccinelli, Martina; Malorgio, Fernando; Pezzarossa, Beatrice

    2017-06-04

    The ability of some crops to accumulate selenium (Se) is crucial for human nutrition and health. Selenium has been identified as a cofactor of the enzyme glutathione peroxidase, which is a catalyzer in the reduction of peroxides that can damage cells and tissues, and can act as an antioxidant. Plants are the first link in the food chain, which ends with humans. Increasing the Se quantity in plant products, including leafy and fruity vegetables, and fruit crops, without exceeding the toxic threshold, is thus a good way to increase animal and human Se intake, with positive effects on long-term health. In many Se-enriched plants, most Se is in its major organic form. Given that this form is more available to humans and more efficient in increasing the selenium content than inorganic forms, the consumption of Se-enriched plants appears to be beneficial. An antioxidant effect of Se has been detected in Se-enriched vegetables and fruit crops due to an improved antioxidative status and to a reduced biosynthesis of ethylene, which is the hormone with a primary role in plant senescence and fruit ripening. This thus highlights the possible positive effect of Se in preserving a longer shelf-life and longer-lasting quality.

  7. Selenium Enrichment of Horticultural Crops

    Directory of Open Access Journals (Sweden)

    Martina Puccinelli

    2017-06-01

    Full Text Available The ability of some crops to accumulate selenium (Se is crucial for human nutrition and health. Selenium has been identified as a cofactor of the enzyme glutathione peroxidase, which is a catalyzer in the reduction of peroxides that can damage cells and tissues, and can act as an antioxidant. Plants are the first link in the food chain, which ends with humans. Increasing the Se quantity in plant products, including leafy and fruity vegetables, and fruit crops, without exceeding the toxic threshold, is thus a good way to increase animal and human Se intake, with positive effects on long-term health. In many Se-enriched plants, most Se is in its major organic form. Given that this form is more available to humans and more efficient in increasing the selenium content than inorganic forms, the consumption of Se-enriched plants appears to be beneficial. An antioxidant effect of Se has been detected in Se-enriched vegetables and fruit crops due to an improved antioxidative status and to a reduced biosynthesis of ethylene, which is the hormone with a primary role in plant senescence and fruit ripening. This thus highlights the possible positive effect of Se in preserving a longer shelf-life and longer-lasting quality.

  8. The isotopic enrichment of uranium in 1979

    International Nuclear Information System (INIS)

    Baron, M.

    1979-01-01

    The Eurodif uranium enrichment plant built on the Tricastin site is described. The uranium isotope separation plants in service abroad are presented. The main characteristics of the international enrichment market are defined [fr

  9. Uranium enrichment (a strategy analysis overview)

    International Nuclear Information System (INIS)

    Blahnik, C.

    1979-08-01

    An analysis of available information on enrichment technology, separative work supply and demand, and SWU cost is presented. Estimates of present and future enrichment costs are provided for use in strategy analyses of alternate nuclear fuel cycles and systems. (auth)

  10. Curriculum enrichment through indigenous Zulu games | Roux ...

    African Journals Online (AJOL)

    Curriculum enrichment through indigenous Zulu games. ... 1997). The aim of the study was to document and analyze indigenous Zulu games for possible curriculum enrichment of physical ... AJOL African Journals Online. HOW TO USE AJOL.

  11. Network-based functional enrichment

    Directory of Open Access Journals (Sweden)

    Poirel Christopher L

    2011-11-01

    Full Text Available Abstract Background Many methods have been developed to infer and reason about molecular interaction networks. These approaches often yield networks with hundreds or thousands of nodes and up to an order of magnitude more edges. It is often desirable to summarize the biological information in such networks. A very common approach is to use gene function enrichment analysis for this task. A major drawback of this method is that it ignores information about the edges in the network being analyzed, i.e., it treats the network simply as a set of genes. In this paper, we introduce a novel method for functional enrichment that explicitly takes network interactions into account. Results Our approach naturally generalizes Fisher’s exact test, a gene set-based technique. Given a function of interest, we compute the subgraph of the network induced by genes annotated to this function. We use the sequence of sizes of the connected components of this sub-network to estimate its connectivity. We estimate the statistical significance of the connectivity empirically by a permutation test. We present three applications of our method: i determine which functions are enriched in a given network, ii given a network and an interesting sub-network of genes within that network, determine which functions are enriched in the sub-network, and iii given two networks, determine the functions for which the connectivity improves when we merge the second network into the first. Through these applications, we show that our approach is a natural alternative to network clustering algorithms. Conclusions We presented a novel approach to functional enrichment that takes into account the pairwise relationships among genes annotated by a particular function. Each of the three applications discovers highly relevant functions. We used our methods to study biological data from three different organisms. Our results demonstrate the wide applicability of our methods. Our algorithms are

  12. Enriched uranium sales: effect on supply industry

    International Nuclear Information System (INIS)

    Andersen, R.K.

    1985-01-01

    The subject is covered in sections: introduction (combined effect of low-enriched uranium (LEU) inventory sales and utility services enrichment contract terms); enrichment market overview; enrichment market dynamics; the reaction of the US Department of Energy; elimination of artificial demand; draw down of inventories; purchase and sale of LEU inventories; tails assay option; unfulfilled requirements for U 3 O 8 ; conclusions. (U.K.)

  13. 31 CFR 540.316 - Uranium enrichment.

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Uranium enrichment. 540.316 Section 540.316 Money and Finance: Treasury Regulations Relating to Money and Finance (Continued) OFFICE OF... REGULATIONS General Definitions § 540.316 Uranium enrichment. The term uranium enrichment means the process of...

  14. Benefits of Low Boron Core Design Concept for PWR

    Energy Technology Data Exchange (ETDEWEB)

    Daing, Aung Tharn; Kim, Myung Hyun [Kyung Hee University, Yongin (Korea, Republic of)

    2009-10-15

    Nuclear design study was carried out to develop low boron core (LBC) based on one of current PWR concepts, OPR-1000. Most of design parameters were the same with those of Ulchin unit-5 except extensive utilization of burnable poison (BP) pins in order to compensate reactivity increase in LBC. For replacement of reduced soluble boron concentration, four different kinds of integral burnable absorbers (IBAs) such as gadolinia, integral fuel burnable absorber (IFBA), erbia and alumina boron carbide were considered in suppressing more excess reactivity. A parametric study was done to find the optimal core options from many design candidates for fuel assemblies and cores. Among them, the most feasible core design candidate was chosen in accordance with general design requirements. In this paper, the feasibility and design change benefits of the most favorable LBC design were investigated in more detail through the comparison of neutronic and thermal hydraulic design parameters of LBC with the reference plant (REF). As calculation tools, the HELIOS/MASTER code package and the MATRA code were utilized. The main purpose of research herein is to estimate feasibility and capability of LBC which was mainly designed to mitigate boron dilution accident (BDA), and for reduction of corrosion products. The LBC design concept using lower boron concentration with an elevated enrichment in {sup 10}B allows a reduction in the concentration of lithium in the primary coolant required to maintain the optimum coolant pH. All in all, LBC with operation at optimum pH is expected to achieve some benefits from radiation source reduction of reduced corrosion product, the limitation of the Axial Offset Anomaly (AOA) and fuel cladding corrosion. Additionally, several merits of LBC are closely related to fluid systems and system related aspects, reduced boron and lithium costs, equipment size reduction for boric acid systems, elimination of heat tracing, and more aggressive fuel design concepts.

  15. Benefits of Low Boron Core Design Concept for PWR

    International Nuclear Information System (INIS)

    Daing, Aung Tharn; Kim, Myung Hyun

    2009-01-01

    Nuclear design study was carried out to develop low boron core (LBC) based on one of current PWR concepts, OPR-1000. Most of design parameters were the same with those of Ulchin unit-5 except extensive utilization of burnable poison (BP) pins in order to compensate reactivity increase in LBC. For replacement of reduced soluble boron concentration, four different kinds of integral burnable absorbers (IBAs) such as gadolinia, integral fuel burnable absorber (IFBA), erbia and alumina boron carbide were considered in suppressing more excess reactivity. A parametric study was done to find the optimal core options from many design candidates for fuel assemblies and cores. Among them, the most feasible core design candidate was chosen in accordance with general design requirements. In this paper, the feasibility and design change benefits of the most favorable LBC design were investigated in more detail through the comparison of neutronic and thermal hydraulic design parameters of LBC with the reference plant (REF). As calculation tools, the HELIOS/MASTER code package and the MATRA code were utilized. The main purpose of research herein is to estimate feasibility and capability of LBC which was mainly designed to mitigate boron dilution accident (BDA), and for reduction of corrosion products. The LBC design concept using lower boron concentration with an elevated enrichment in 10 B allows a reduction in the concentration of lithium in the primary coolant required to maintain the optimum coolant pH. All in all, LBC with operation at optimum pH is expected to achieve some benefits from radiation source reduction of reduced corrosion product, the limitation of the Axial Offset Anomaly (AOA) and fuel cladding corrosion. Additionally, several merits of LBC are closely related to fluid systems and system related aspects, reduced boron and lithium costs, equipment size reduction for boric acid systems, elimination of heat tracing, and more aggressive fuel design concepts

  16. Gas-phase UF6 enrichment monitor for enrichment plant safeguards

    International Nuclear Information System (INIS)

    Strittmatter, R.B.; Tape, J.W.

    1980-03-01

    An in-line enrichment monitor is being developed to provide real-time enrichment data for the gas-phase UF 6 feed stream of an enrichment plant. The nondestructive gamma-ray assay method can be used to determine the enrichment of natural UF 6 with a relative precision of better than 1% for a wide range of pressures

  17. 76 FR 11523 - Atomic Safety and Licensing Board; AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility...

    Science.gov (United States)

    2011-03-02

    ... and Licensing Board; AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility); Notice of... Governmental Entities Regarding Environmental Portion of Enrichment Facility Licensing Proceeding February 24.... White. In this 10 CFR part 70 proceeding regarding the request of applicant AREVA Enrichment Services...

  18. Enriching Orphans’ Potentials through Interpersonal and Intrapersonal Intelligence Enrichment Activities

    Directory of Open Access Journals (Sweden)

    Nurulwahida Hj Azid

    2016-01-01

    Full Text Available Orphans are considered a minority and they should be given a greater emphasis so that they do not feel left out and can build their own lives without a sense of humility. This does not mean that the orphans should be pampered instead they should be given the confidence and motivation to strive for success in later life. Humility among orphans can be associated with interpersonal and intrapersonal intelligences. This study aims to evaluate the impact of problem-solving activity treatment based on the interpersonal and intrapersonal intelligences. 46 students from two orphanages were involved as the treatment group. The research design used was a one-group pretest-posttest design applied through a combination of quantitative and qualitative approaches. Enrichment activities that provided interpersonal and intrapersonal skills as evidenced in this study should be carried out regularly at orphanages. Our study has proven that orphans‟ rights to learn cannot be neglected and „no child left behind „policy needs to be carried through by everybody involved with orphans‟ well-being. Teachers and carers need to be trained to use these enrichment activities at their orphanages to help maximize the orphans‟ potentials.

  19. The reduced enrichment program for JRR-4

    International Nuclear Information System (INIS)

    Takayanagi, M.

    1992-01-01

    Japan Research Reactor No. 4(JRR-4) with the rated power of 3.5 MW, swimming pool type research reactor, 93 % enriched uranium ETR-type fuel used, light water moderated and cooled. The first criticality reached on 28th January, 1965. The reactor has operated for about 26 years. However, it was planed to the reduced enrichment of the fuels to low enrichment according to the International Reduced Enrichment for Research and Test Reactors (RERTR) program. This paper describes the program for conversion of the enrichment of fuel from 93 % to less than 20 %. (author)

  20. Enrichment planting without soil treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hagner, Mats

    1998-12-31

    Where enrichment planting had been carried out with either of the two species Picea abies and Pinus contorta, the survival of the planted seedlings was at least as good as after planting in a normal clear cut area treated with soil scarification. This was in spite of the fact that the seedlings were placed shallow in the humus layer without any soil treatment. However, they were sheltered from insects by treatment before planting. Where enrichment planting was carried out with Pinus sylvestris the survival in dense forest was poor, but in open forest the survival was good. The growth of planted seedlings was enhanced by traditional clearing and soil treatment. However, this was for Pinus sylvestris not enough to compensate for the loss of time, 1-2 years, caused by arrangement of soil scarification. The growth of seedlings planted under crown cover was directly related to basal area of retained trees. However, the variation in height growth among individual seedlings was very big, which meant that some seedlings grow well also under a fairly dense forest cover. The pioneer species Pinus sylvestris reacted more strongly to basal area of retained trees than did the shade tolerant species Picea abies. Enrichment planting seems to be a necessary tool for preserving volume productivity, at places where fairly intensive harvest of mature trees has been carried out in stands of ordinary forest type in central Sweden. If double seedlings, with one Picea abies and one Pinus sylvestris, are used, the probability for long term establishment is enhanced 13 refs, 20 figs, 4 tabs

  1. [Hydroxylamine conversion by anammox enrichment].

    Science.gov (United States)

    Hu, Anhui; Zheng, Ping; Lu, Huifeng; Ding, Shuang; Wang, Caihua

    2010-04-01

    Hydroxylamine is an important intermediate product of anammox. This study was focused on the characteristics of hydroxylamine and nitrite conversions by anammox enrichment. The changes of nitrogenous substrates and related products with time were measured using batch tests with anammox enrichment as inoculum. Since hydroxylamine didn't react with nitrite in uninoculated control culture, these two compounds were chemically stable. Both of them decreased with time in anammox enrichment inoculated cultures, in which ammonia as intermediate product would be produced and converted with the maximum concentration being 0.338 mg/L. The total nitrogen concentration decreased from 4.694 mmol/L to 0.812 mmol/L with conversion rate 82.7% in the end. When hydroxylamine and nitrite concentrations were about 2.5 mmol/L respectively, the maximum specific sludge conversion rates of hydroxylamine was 0.535 mmol/(gVSS.h), which was 1.81 times bigger than that of ammonia in ammonia reaction system; the maximum specific sludge rate of total nitrogen was slightly higher than that in ammonia reaction system. When hydroxylamine concentration increased to 5.0 mmol/L, the hydroxylamine and nitrite conversion rates promoted by 26.7% and 120.7% respectively; and the maximum ammonia accumulated was 1.810 mmol/L. When nitrite concentration increased to 5.0 mmol/L, the hydroxylamine and nitrite conversion rates promoted by 6.9% and 9.0% respectively; and the maximum ammonia accumulated was 0.795 mmol/L. Anammox enrichment was capable of converting hydroxylamine and nitrite simultaneously and had the higher conversion rate of hydroxylamine than ammonia conversion rate. Hydroxylamine and nitrite conversion rates were less affected by increase in nitrite concentration, but more significantly influenced by increase in hydroxylamine. The maximum ammonia concentration accumulated would rise as the result of increasing both hydroxylamine and nitrite. The result of experiment was consistent with pathway

  2. Boron enrichment in martian clay.

    Directory of Open Access Journals (Sweden)

    James D Stephenson

    Full Text Available We have detected a concentration of boron in martian clay far in excess of that in any previously reported extra-terrestrial object. This enrichment indicates that the chemistry necessary for the formation of ribose, a key component of RNA, could have existed on Mars since the formation of early clay deposits, contemporary to the emergence of life on Earth. Given the greater similarity of Earth and Mars early in their geological history, and the extensive disruption of Earth's earliest mineralogy by plate tectonics, we suggest that the conditions for prebiotic ribose synthesis may be better understood by further Mars exploration.

  3. Producing deuterium-enriched products

    International Nuclear Information System (INIS)

    1980-01-01

    A method of producing an enriched deuterium product from a gaseous feed stream of mixed hydrogen and deuterium, comprises: (a) combining the feed stream with gaseous bromine to form a mixture of the feed stream and bromine and exposing the mixture to an electrical discharge effective to form deuterium bromide and hydrogen bromide with a ratio of D/H greater than the ratio of D/H in the feed stream; and (b) separating at least a portion of the hydrogen bromide and deuterium bromide from the mixture. (author)

  4. Present state of development of uranium enrichment

    International Nuclear Information System (INIS)

    1979-01-01

    The pilot plant for uranium enrichment started the operation on September 12, 1979. The pilot plant has been constructed by the Power Reactor and Nuclear Fuel Development Corp. in Ningyo Pass, Okayama Prefecture. 7000 centrifugal separators will be installed by mid 1981, and yearly production of 70 t SWU is expected. The Uranium Enrichment Committee of Japan Atomic Industrial Forum has made the proposal on the method of forwarding the development of uranium enrichment in Japan to Atomic Energy Commission and related government offices in December, 1978. This survey summarized the trends of uranium enrichment in Japan and foreign countries and the problems about nuclear non-proliferation, and provides with the reference materials. The demand and supply of uranium enrichment in the world, the present states and plans in USA, Europe, USSR and others, the demand and supply of uranium enrichment and the measures for securing it in Japan, the present state and future plan of uranium enrichment project in Japan, the international regulation of uranium enrichment, the recent policy of USA and INFCE, and the trend of the regulation of utilizing enriched uranium are described. Moreover, the concept of separation works in uranium enrichment and the various technologies of separation are explained. (Kako, I.)

  5. Gasket for uranium enrichment plant

    Energy Technology Data Exchange (ETDEWEB)

    Kishi, S; Aiyoshi, H

    1977-02-08

    A gasket to be inserted between flange joints in the equipments and pipe lines of an uranium enrichment plant having neither permeability nor adsorptivity to water while maintaining mechanical, physical and chemical properties of an elastomer gasket is described. A gasket made of an elastomeric material such as a polymer is integratedly formed at its surface with anti-slip projections. The gasket is further surrounded at its upper and lower peripheral sides, as well as outer circumferential portion with a U-sectioned cover (enclosure) made of fluoro-plastics. In this arrangement, the gasket main body shows a gas-tightness for uranium hexafluoride gas and the cover exhibits a gas-tightness for other component gases such as moisture to thereby prevent degradation of the gasket due to absorption and permeation of the moisture.

  6. Uranium enrichment in South Africa

    International Nuclear Information System (INIS)

    Roux, A.J.A.; Grant, W.L.

    1976-01-01

    It is stated that the South African process is of an aerodynamic type, the separating element being in effect a high performance stationary-walled centrifuge using UF 6 in hydrogen as process fluid. Some details of the very low uranium inventory and high separation factor achievable are given. A new cascade technique is described, based on the principle that an axial flow compressor can simultaneously transmit several streams of different isotopic composition without there being significant mixing between them. The research and development programme is discussed. It is expected that an enrichment plant of 5000 t/a SW capacity, with provision for expansion up to 10,000 t/a SW capacity, will come into operation by 1984. (U.K.)

  7. Stable isotope enrichment: Current and future potential

    International Nuclear Information System (INIS)

    Tracy, J.G.; Aaron, W.S.

    1992-01-01

    Oak Ridge National Laboratory (ORNL) operates the Isotope Enrichment Facility for the purpose of providing enriched stable isotopes, selected radioactive isotopes (including the actinides), and isotope-related materials and services for use in various research applications. ORNL is responsible for isotope enrichment and the distribution of approximately 225 nongaseous stable isotopes from 50 multi-isotopic elements. Many enriched isotope products are of prime importance in the fabrication of nuclear targets and the subsequent production of special radionuclides. State-of-the-art techniques to achieve special isotopic, chemical, and physical requirements are performed at ORNL This report describes the status and capabilities of the Isotope Enrichment Facility and the Isotope Research Materials Laboratory as well as emphasizing potential advancements in enrichment capabilities

  8. Considering the post-1995 enrichment market

    International Nuclear Information System (INIS)

    Gunter, L.

    1994-01-01

    World demand for uranium enrichment services is likely to grow only a little over the next decade, from the current 28 million separative work units (SWU) per year to 33 MSWU per year. Much of the growth will come from Asia where nuclear generating capacity is still increasing. The current situation of the primary enrichment companies is summarized. The primary Western suppliers, Cogema, United States Enrichment Corporation and Urenco, are competing for increased market share in the USA, Europe and Asia as utilities purchase their post-1995 requirements. Entry of the Russian enrichment company, Tenex, into Western markets has been limited by trade restrictions. As a consequence of disarmament, blended weapons material has resulted in a surplus of low-enriched uranium. Together with over-capacity amongst the primary enrichers this has led to an expectation that reduced prices will be negotiable in the medium term. (3 figures). (UK)

  9. Noble gas enrichment studies at JET

    International Nuclear Information System (INIS)

    Groth, M.; Andrew, P.; Fundamenski, W.; Guo, H.Y.; Hillis, D.L.; Hogan, J.T.; Horton, L.D.; Matthews, G.F.; Meigs, A.G.; Morgan, P.M.; Stamp, M.F.; Hellermann, M. von

    2001-01-01

    Adequate helium exhaust has been achieved in reactor-relevant ELMy H-mode plasmas in JET performed in the MKII AP and MKII GB divertor geometry. The divertor-characteristic quantities of noble gas compression and enrichment have been experimentally inferred from Charge Exchange Recombination Spectroscopy measurements in the core plasma, and from spectroscopic analysis of a Penning gauge discharge in the exhaust gas. The retention of helium was found to be satisfactory for a next-step device, with enrichment factors exceeding 0.1. The helium enrichment decreases with increasing core plasma density, while the neon enrichment has the opposite behaviour. Analytic and numerical analyses of these plasmas using the divertor impurity code package DIVIMP/NIMBUS support the explanation that the enrichment of noble gases depends significantly on the penetration depth of the impurity neutrals with respect to the fuel atoms. Changes of the divertor plasma configuration and divertor geometry have no effect on the enrichment

  10. Stable isotope enrichment - current and future potential

    International Nuclear Information System (INIS)

    Tracy, J.G.; Aaron, W.S.

    1993-01-01

    Oak Ridge National Laboratory (ORNL) operates the Isotope Enrichment Facility for the purpose of providing enriched stable isotopes, selected radioactive isotopes (including the actinides), and isotope-related materials and services for use in various research applications. ORNL is responsible for isotope enrichment and the distribution of approximately 225 nongaseous stable isotopes from 50 multi-isotopic elements. Many enriched isotope products are of prime importance in the fabrication of nuclear targets and the subsequent production of special radionuclides. State-of-the-art techniques to achieve special isotopic, chemical, and physical requirements are performed at ORNL. This report describes the status and capabilities of the Isotope Enrichment Facility and the Isotope Research Materials Laboratory as well as emphasizing potential advancements in enrichment capabilities. (orig.)

  11. Turkey's regulatory plans for high enriched to low enriched conversion of TR-2 reactor core

    International Nuclear Information System (INIS)

    Guelol Oezdere, Oya

    2003-01-01

    Turkey is a developing country and has three nuclear facilities two of which are research reactors and one pilot fuel production plant. One of the two research reactors is TR-2 which is located in Cekmece site in Istanbul. TR-2 Reactor's core is composed of both high enriched and low enriched fuel and from high enriched to low enriched core conversion project will take place in year 2005. This paper presents the plans for drafting regulations on the safety analysis report updates for high enriched to low enriched core conversion of TR-2 reactor, the present regulatory structure of Turkey and licensing activities of nuclear facilities. (author)

  12. EURODIF: the uranium enrichment by gaseous diffusion

    International Nuclear Information System (INIS)

    Rougeau, J.P.

    1981-01-01

    During the seventies the nuclear power programme had an extremely rapid growth rate which entailed to increase the world uranium enrichment capacity. EURODIF is the largest undertaking in this field. This multinational joint venture built and now operates and enrichment plant using the gaseous diffusion process at Tricastin (France). This plant is delivering low enriched uranium since two years and has contracted about 110 million SWU's till 1990. Description, current activity and prospects are given in the paper. (Author) [pt

  13. The future cost of uranium enrichment

    International Nuclear Information System (INIS)

    Pouris, A.

    1986-01-01

    The cost of uranium enrichment is the most important factor determining the fuel cost of nuclear energy. This paper attempts to forecast the future direction of the price of separative work by examining the forces that determine it. It is argued that the interplay among the characteristics of enrichment technologies, the structure of the international market, and the balance of supply and demand determine the enrichment price. The analysis indicates that all forces point towards a price much lower than the current one. It is predicted that, depending on the technological advances, the price of separative work unit for uranium enrichment will range between $40 and $90 by the year 2000. (author)

  14. 76 FR 387 - Atomic Safety and Licensing Board; AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility)

    Science.gov (United States)

    2011-01-04

    ... and Licensing Board; AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility) December 17, 2010... construction and operation of a gas centrifuge uranium enrichment facility--denoted as the Eagle Rock... site at http://www.nrc.gov/materials/fuel-cycle-fac/arevanc.html . These and other documents relating...

  15. Study on the radiotoxicology of enriched uranium

    International Nuclear Information System (INIS)

    Zhu Shoupeng; Zheng Siying; Wang Guolin; Wang Chongdao; Cao Genfa

    1987-12-01

    A study on the retentive peculiarity of soluble enriched uranium UO 2 F 2 were observed after iv once or consecutive ip qd x 3d to Wistar male rats. The dynamic retention of radioactivity in the body showed that the enriched uranium UO 2 F 2 was chiefly localized in kidney, and then in skeleton and liver. The radioactivity of the enriched uranium UO 2 F 2 in skeleton rose steadily while the concentratoin in kidney and liver droped. When enriched uranium UO 2 F 2 was accumulated in organism, it caused chromosome aberrations on bone marrow cells. Results indicated that the chromosome aberration rates were elevated when the dose of the enriched uranium UO 2 F 2 was increased, at the same time, the cell division was depressed. Accumulation of insoluble enriched uranium U 3 O 8 in gastrointestinal tract was well described by a two exponential expression. Values of retention estimate for fast component, T 1 = 0.34 d, and for relatively long term component, T 2 = 4.05 d. The deposition of UO 2 F 2 in the intact skin was only 0.16 to 0.18% of the total contaminated UO 2 F 2 . Penetration of the enriched uranium UO 2 F 2 was dominantly increased in abraded skin. This value is about 25 to 32 times as compaired with that in intact skin. Retention of the enriched uranium UO 2 F 2 through abraded skins was dominantly localized in kidney and skeleton

  16. Uranium enrichment: a vital new industry

    International Nuclear Information System (INIS)

    1975-10-01

    The energy problem facing the nation and the need for nuclear power are pointed out. Uranium enrichment and the demand for it are discussed. Reasons for, and obstacles to, private enrichment are outlined. The President's plan (including the Nuclear Fuel Assurance Act) is summarized

  17. Inoculation stress hypothesis of environmental enrichment.

    Science.gov (United States)

    Crofton, Elizabeth J; Zhang, Yafang; Green, Thomas A

    2015-02-01

    One hallmark of psychiatric conditions is the vast continuum of individual differences in susceptibility vs. resilience resulting from the interaction of genetic and environmental factors. The environmental enrichment paradigm is an animal model that is useful for studying a range of psychiatric conditions, including protective phenotypes in addiction and depression models. The major question is how environmental enrichment, a non-drug and non-surgical manipulation, can produce such robust individual differences in such a wide range of behaviors. This paper draws from a variety of published sources to outline a coherent hypothesis of inoculation stress as a factor producing the protective enrichment phenotypes. The basic tenet suggests that chronic mild stress from living in a complex environment and interacting non-aggressively with conspecifics can inoculate enriched rats against subsequent stressors and/or drugs of abuse. This paper reviews the enrichment phenotypes, mulls the fundamental nature of environmental enrichment vs. isolation, discusses the most appropriate control for environmental enrichment, and challenges the idea that cortisol/corticosterone equals stress. The intent of the inoculation stress hypothesis of environmental enrichment is to provide a scaffold with which to build testable hypotheses for the elucidation of the molecular mechanisms underlying these protective phenotypes and thus provide new therapeutic targets to treat psychiatric/neurological conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Perspectives for the uranium enrichment in Brazil

    International Nuclear Information System (INIS)

    Senna, J.G.S.M.

    1991-01-01

    Through an analysis of the electrical energy future in Brazil, the needs for enriched uranium are discussed, and therefore the importance of developing local capability for self-production. A description of the production processes that are well established is given first, then the analysis itself is performed and finally a visualization of the International Market for enriched uranium is shown. (author)

  19. Uranium enrichment : global view and Brazilian perspectives

    International Nuclear Information System (INIS)

    Zouain, D.M.; Sakamoto, L.H.

    1981-12-01

    A global view of isotope enrichment involving a general description of process (technical-economical aspects and policy) and status in developing countries is done. An enrichment demand in function of the Brazilian Nuclear Program is evaluated, analyzing a probable market and a low market. The perspectives to attend this demand, are studied. (E.G.) [pt

  20. 21 CFR 137.350 - Enriched rice.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Enriched rice. 137.350 Section 137.350 Food and... Related Products § 137.350 Enriched rice. (a) The foods for which definitions and standards of identity are prescribed by this section are forms of milled rice (except rice coated with talc and glucose and...

  1. Providing incentives to buy US enrichment

    International Nuclear Information System (INIS)

    Steyn, J.

    1985-01-01

    The U.S. Department of Energy is making a series of commercial and technological decisions crucial to its future as an enriching enterprise. The state of US enrichment, as revealed in this years AIF Fuel Cycle conference, is reported. (U.K.)

  2. Enrichment technology. Dependable vendor of gas centrifuges

    International Nuclear Information System (INIS)

    Anon.

    2011-01-01

    Enrichment Technology is an innovative, high-tech company that develops, manufactures and installs gas centrifuges for enriching uranium. In addition, Enrichment Technology designs enrichment plants that use gas centrifuge technology. This technology offers the most efficient and cost-effective method for enriching uranium yet: high-performance, safe technology that dominates the market with a global share of 45 percent. A determining factor in Enrichment Technology's success is its mission: supplying its customers with safe, reliable technology. Production of the centrifuges requires versatile know-how and collaboration between different departments as well as interdisciplinary teams at the various sites. More than 2000 operators at 8 sites in 5 countries contribute their individual knowledge and personal skills in order to produce this exceptional technology. The head office is in Beaconsfield near London and the operational headquarters are in Almelo in the Netherlands. There are other sites in Germany (Juelich und Gronau), Great Britain (Capenhurst) as well as project sites in the USA and France. Capenhurst is where experienced engineers design new enrichment plants and organise their construction. Centrifuge components are manufactured in Almelo and Juelich, while the pipework needed to connect up the centrifuges is produced at the site in Gronau. In Juelich, highly qualified scientists in interdisciplinary teams are continuously researching ways of improving the current centrifuges. Communication between specialists in the fields of chemistry, physics and engineering forms the basis for the company's success and the key to extending this leading position in the global enrichment market. (orig.)

  3. Student science enrichment training program

    Energy Technology Data Exchange (ETDEWEB)

    Sandhu, S.S.

    1994-08-01

    This is a report on the Student Science Enrichment Training Program, with special emphasis on chemical and computer science fields. The residential summer session was held at the campus of Claflin College, Orangeburg, SC, for six weeks during 1993 summer, to run concomitantly with the college`s summer school. Fifty participants selected for this program, included high school sophomores, juniors and seniors. The students came from rural South Carolina and adjoining states which, presently, have limited science and computer science facilities. The program focused on high ability minority students, with high potential for science engineering and mathematical careers. The major objective was to increase the pool of well qualified college entering minority students who would elect to go into science, engineering and mathematical careers. The Division of Natural Sciences and Mathematics and engineering at Claflin College received major benefits from this program as it helped them to expand the Departments of Chemistry, Engineering, Mathematics and Computer Science as a result of additional enrollment. It also established an expanded pool of well qualified minority science and mathematics graduates, which were recruited by the federal agencies and private corporations, visiting Claflin College Campus. Department of Energy`s relationship with Claflin College increased the public awareness of energy related job opportunities in the public and private sectors.

  4. Uranium enrichment capacity: public versus private ownership

    International Nuclear Information System (INIS)

    Fraser, J.T.

    1977-01-01

    Continual growth of conventional nuclear capacity requires an assured supply of enriched uranium and, hence, potential expansion of domestic uranium enrichment capacity. The question of ownership of new enrichment capacity, i.e., public or private, entails not only the social-opportunity costs of alternative investments but also technical parameters of uranium utilization and advanced reactor development. Inclusion of risk preferences in both the public and private sectors produces interesting results in terms of optimal investment strategies with respect to choice of technology and scale of investment. Utilization of a nuclear fuel cycle requirements process model allows explicit specification of production technology. Integration of process model output with a least-cost investment model permits flexibility in parametric analysis. Results indicate minimum incentive for Government subsidy of a private enrichment sector through 2000 given moderate to low nuclear growth assumptions. The long-run scenario, to 2020, exhibits potentially greater incentives for private enrichment investment

  5. Enriching an effect calculus with linear types

    DEFF Research Database (Denmark)

    Egger, Jeff; Møgelberg, Rasmus Ejlers; Simpson, Alex

    2009-01-01

    We define an ``enriched effect calculus'' by conservatively extending  a type theory for computational effects with primitives from linear logic. By doing so, we obtain a generalisation of linear type theory, intended as a formalism for expressing linear aspects of effects. As a worked example, we...... formulate  linearly-used continuations in the enriched effect calculus. These are captured by a fundamental translation of the enriched effect calculus into itself, which extends existing call-by-value and call-by-name linearly-used CPS translations. We show that our translation is involutive. Full...... completeness results for the various linearly-used CPS translations  follow. Our main results, the conservativity of enriching the effect calculus with linear primitives, and the involution property of the fundamental translation, are proved using a category-theoretic semantics for the enriched effect calculus...

  6. Review of environmental enrichment for broiler chickens

    DEFF Research Database (Denmark)

    Riber, Anja Brinch; Van de Weerd, H.A.; de Jong, I.C.

    2018-01-01

    to improvements of the biological function. This definition has been broadened to include practical and economic aspects, as any enrichment strategy that adversely affects the health of animals or that has too many economic or practical constraints will never be implemented on commercial farms and thus never...... benefit animals. Environmental enrichment for broilers often has the purpose of satisfying behavioral needs and/or stimulating the broilers to an increased level of activity, which among others will reduce the occurrence of leg problems. Potentially successful environmental enrichments for broiler...... chickens are elevated resting-places, panels, barriers, and bales of straw (“point-source enrichment”), as well as covered verandas and outdoor ranges (“complex enriched environments”). Many of the ideas for environmental enrichment for broilers need to be further developed and studied, preferably...

  7. Current perspective of the uranium enrichment market

    International Nuclear Information System (INIS)

    Laughon, K.O.

    1986-01-01

    Over the past several years, developments in the uranium enrichment market have required the Department of Energy (DOE) to make a number of changes in the U.S. enrichment enterprise. These changes have been made to allow DOE to conduct our enrichment business so as to be more responsive to changing market forces. Needless to say, some of these changes have been difficult, but they have been necessary if they are to conduct a healthy and competitive uranium enrichment business in the United States. This paper discusses several topics, including: The Uranium Enrichment Market, Utility Services (US) Contracts, Reduced Prices, Incentive Pricing, Better Customer Services, and Advanced Technology. In addition to these topics, information is provided on the recent court action regarding the US Contracts and the viability finding on the uranium mining industry

  8. The low-enrichment fuel development program

    International Nuclear Information System (INIS)

    Stahl, D.

    1993-01-01

    In the 1950s and 1960s, low-power research reactors were built around the world utilized MTR-type fuel elements containing 20% enriched uranium. However, the demand for higher specific power created a need for greater uranium-235 concentrations. Early difficulties in increasing uranium content led to the substitution of highly enriched uranium in place of the 20% enriched fuel previously utilized. The highly enriched material also yielded other benefits including longer core residence time, higher specific reactivity, and somewhat lower cost. Highly enriched material then became readily available and was used for high-power reactors as well as in low-power reactors where 20% enriched material would have sufficed. The trend toward higher and higher specific power also led to the development of the dispersion-type fuels which utilized highly enriched uranium at a concentration of about 40 wt%. In the 1970's, however, concerns were raised about the proliferation resistance of fuels and fuel cycles. As a consequence, the U.S. Department of State has recently prohibited the foreign shipment of highly enriched material, except where prior contractual obligation or special merit exists. This will impact on the availability and utilization of highly enriched uranium for research and test reactor fuel. It has also stimulated development programs on fuels with higher uranium content which would allow the use of uranium of lower enrichment. The purpose of this report is to briefly describe the overall fuel-development program which is coordinated by Argonne National Laboratory for the Department of Energy, and to indicate the current and potential uranium loadings. Other reports will address the individual fuel-development activities in greater detail

  9. Comments on applications of reduced enrichment fuels

    International Nuclear Information System (INIS)

    Winkler, M.H.

    1983-01-01

    Full text: I will briefly describe the experience gained using different fuels in the SAPHIR reactor in Switzerland. The SAPHIR has been operating since 1957 and was the first swimming pool reactor built outside of the United States, which was originally known as the Geneva Conference Reactor. The first core was loaded with 20 percent enriched high density UO 2 fuel with a density of about 2.5 grams per cc, fabricated in 1955 by Oak Ridge National Laboratory. After a few years of operation at a power level of one MW, more than one batch of the elements released small amounts of fission products mainly Xe and Kr. When these releases were discovered, high enriched fuel was becoming available so that the fuel fabricators began to produce the lower density high enriched fuels. During this transition from fabrication of low to high enriched fuels no one could foresee that the stone age of nuclear fuel fabrication would come back again. Therefore, we did not investigate the reasons for the fission product release from the high density low enriched UO 2 fuel. The second fuel type used in the SAPHIR was the 90 percent enriched low density U 3 O 8 fuel fabricated by NUKEM. This high enriched fuel has performed satisfactorily over the years. Since 1968, the core has been using improved 23 plate fuel elements with a loading of 280 grams of uranium. The reactor power has been recently increased to five MW. An additional increase in the power level to 10 MW is planned at the end of next year so that heavier loaded elements will be needed. In order to follow the recommendations of the INFCE working group 8C and in cooperation with the reduced enrichment program, we intend to initially reduce the fuel enrichment to 45 percent. Last year we ordered five fuel elements with a loading of 320 grams 235 U/element and 45 percent enrichment for full power tests. Unfortunately, the delivery of the necessary enriched fuel uranium has been delayed and it is not available at this time. If

  10. Study of the neutronic behavior of a fuel assembly with gadolinium of a reactor HPLWR; Estudio del comportamiento neutronico de un ensamble combustible con gadolinia de un reactor HPLWR

    Energy Technology Data Exchange (ETDEWEB)

    Barragan M, A.; Martin del Campo M, C.; Francois L, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Espinosa P, G., E-mail: albrm29@yahoo.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)

    2012-10-15

    This work presents a neutronic study of a square assembly design of double line of fuel rods, with moderator box to center of the arrangement, for the nuclear reactor cooled with supercritical water, High Performance Light Water Reactor (HPLWR). For the fuel analyses of the reactor HPLWR the neutronic code Helios-2 was used, settling down as the first study on fuel under conditions of supercritical water that has been simulated with this code. The analyzed variables, essentials in the neutronic design of any reactor, were the infinite neutrons multiplication factor (k{infinity}) and the maximum power peaking factor (PPF{sub max}), as well as the reactivity coefficients by the fuel temperature. The k{infinity} and PPF{sub max} values were obtained under conditions in cold (293.6 K) and in hot (to 880.8 K). The tests were realized for a reference fuel assembly design, with 40 fuel rods with enrichments of 4 and 5% of U-235, and considering different concentrations of consumable poison (gadolinium - Gd{sub 2O3}) in some rods of the same assembly. The obtained results show values k{infinity} and PPF{sub max} minors to the present in the conventional light water reactors. Moreover, the reactivity coefficients by fuel temperature were verified with the purpose of satisfying the safety conditions required in the nuclear reactors. (Author)

  11. DOE enrichment plants-safeguards means business

    International Nuclear Information System (INIS)

    Donnelly, R.

    1987-01-01

    The Portsmouth Gaseous Diffusion Plant, owned by the US Department of Energy (DOE) and operated by Martin Marietta Energy Systems, Inc., is a full service enrichment plant. Its long enriching cascade can process uranium hexafluoride (UF 6 ) feeds at almost any 235 U level and can produce UF 6 over the complete spectrum from depleted to very highly enriched uranium. The DOE uranium enrichment program is a government-owned enterprise operating as a business. The operating concerns of the DOE uranium enrichment plants and their safeguards programs have evolved together over the past three decades, and that evolution will likely continue. As the risk associated with possession, processing, and shipment of strategic nuclear material increased, the protection and control of it increased; as the value of the product grew with time, better ways were found to measure and conserve it. In each of these areas, safeguards objectives and the business requirements of the plant are complementary, and the progress made in one area has been reflected by progress in the other. The plant's material control and accountability program has become crucial to such business requirements as quantifying the enriched uranium (separative work units) produced in each monthly period and convincing financial auditors that the multibillion dollar enriched uranium assets located at the Portsmouth plant are properly stated

  12. Multinational uranium enrichment in the Middle East

    International Nuclear Information System (INIS)

    Ahmad, Ali; Salahieh, Sidra; Snyder, Ryan

    2017-01-01

    The Joint Comprehensive Plan of Action (JCPOA) agreed to by Iran and the P5+1 in July 2015 placed restrictions on Iran’s nuclear program while other Middle Eastern countries– Egypt, Jordan, Saudi Arabia, Turkey, and the United Arab Emirates–are planning to build their own nuclear power plants to meet increasing electricity demands. Although the JCPOA restricts Iran's uranium enrichment program for 10–15 years, Iran's neighbors may choose to develop their own national enrichment programs giving them a potential nuclear weapons capability. This paper argues that converting Iran's national enrichment program to a more proliferation-resistant multinational arrangement could offer significant economic benefits–reduced capital and operational costs–due to economies of scale and the utilization of more efficient enrichment technologies. In addition, the paper examines policy aspects related to financing, governance, and how multinational enrichment could fit into the political and security context of the Middle East. A multinational enrichment facility managed by regional and international partners would provide more assurance that it remains peaceful and could help build confidence between Iran and its neighbors to cooperate in managing other regional security challenges. - Highlights: • Freezing Iran's nuclear program is an opportunity to launch joint initiatives in ME. • A joint uranium enrichment program in the Middle East offers economic benefits. • Other benefits include improved nuclear security and transparency in the region.

  13. Uranium enrichment: heading for a cliff

    International Nuclear Information System (INIS)

    Norman, C.

    1987-01-01

    Thanks to drastic cost cutting in the past 2 years, US enrichment plants now have the lowest cost production in the world, but US prices are still higher than those of overseas competitors because the business is paying for past mistakes. The most serious difficulty is that the Department of Energy (DOE), which owns and operates the US enrichment enterprise, is paying more than $500 million a year to the Tennessee Valley Authority (TVA) for electricity it once thought it would need but no longer requires. Another is that billions of dollars were spent in the 1970s and early 1980s to build new capacity that is now not needed. As a result, the enrichment enterprise has accumulated a debt to the US Treasury that the General Accounting Office (GAO) estimates at $8.8 billion. This paper presents the background and current debate in Congress about the difficulties facing the enrichment industry. In the midst of this debate over the future of the enterprise, the development of the next generation of enrichment technology is being placed in jeopardy. Known as atomic vapor laser isotope separation, or AVLIS, the process was viewed as the key to the long-term competitiveness of US enrichment. As the federal deficit mounted, however, funding for the AVLIS program was cut back and the timetable was stretched out. The US enrichment program has reached the point at which Congress will be forced to make some politically difficult decisions

  14. Enrichment of Acinetobacter spp. from food samples.

    Science.gov (United States)

    Carvalheira, Ana; Ferreira, Vânia; Silva, Joana; Teixeira, Paula

    2016-05-01

    Relatively little is known about the role of foods in the chain of transmission of acinetobacters and the occurrence of different Acinetobacter spp. in foods. Currently, there is no standard procedure to recover acinetobacters from food in order to gain insight into the food-related ecology and epidemiology of acinetobacters. This study aimed to assess whether enrichment in Dijkshoorn enrichment medium followed by plating in CHROMagar™ Acinetobacter medium is a useful method for the isolation of Acinetobacter spp. from foods. Recovery of six Acinetobacter species from food spiked with these organisms was compared for two selective enrichment media (Baumann's enrichment and Dijkshoorn's enrichment). Significantly (p enrichment. Next, the Dijkshoorn's enrichment followed by direct plating on CHROMagar™ Acinetobacter was applied to detect Acinetobacter spp. in different foods. Fourteen different presumptive acinetobacters were recovered and assumed to represent nine different strains on the basis of REP-PCR typing. Eight of these strains were identified by rpoB gene analysis as belonging to the species Acinetobacter johnsonii, Acinetobacter calcoaceticus, Acinetobacter guillouiae and Acinetobacter gandensis. It was not possible to identify the species level of one strain which may suggests that it represents a distinct species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Review of environmental enrichment for broiler chickens.

    Science.gov (United States)

    Riber, A B; van de Weerd, H A; de Jong, I C; Steenfeldt, S

    2018-02-01

    Welfare problems are commonly found in both conventional and organic production of broiler chickens. In order to reduce the extent of welfare problems, it has been suggested to provide stimulating, enriched environments. The aim of the present paper is to provide a review of the effect on behavior and welfare of the different kinds of environmental enrichments in the production of broilers that have been described in the scientific literature. Environmental enrichment is defined as an improvement of the environment of captive animals, which increases the behavioral opportunities of the animal and leads to improvements of the biological function. This definition has been broadened to include practical and economic aspects, as any enrichment strategy that adversely affects the health of animals or that has too many economic or practical constraints will never be implemented on commercial farms and thus never benefit animals. Environmental enrichment for broilers often has the purpose of satisfying behavioral needs and/or stimulating the broilers to an increased level of activity, which among others will reduce the occurrence of leg problems. Potentially successful environmental enrichments for broiler chickens are elevated resting-places, panels, barriers, and bales of straw ("point-source enrichment"), as well as covered verandas and outdoor ranges ("complex enriched environments"). Many of the ideas for environmental enrichment for broilers need to be further developed and studied, preferably in commercial trials, with respect to the use, the effect on behavior and on other welfare aspects such as leg health, and the interaction with genotype, production system, stocking density, light, and flock size. In addition, information on the practical application and the economics of the production system is often lacking, although it is important for application in practice. © 2017 Poultry Science Association Inc.

  16. Profile of World Uranium Enrichment Programs - 2007

    International Nuclear Information System (INIS)

    Laughter, Mark D.

    2007-01-01

    It is generally agreed that the most difficult step in building a nuclear weapon is acquiring weapons grade fissile material, either plutonium or highly enriched uranium (HEU). Plutonium is produced in a nuclear reactor, while HEU is produced using a uranium enrichment process. Enrichment is also an important step in the civil nuclear fuel cycle, in producing low enriched uranium (LEU) for use in fuel for nuclear reactors. However, the same equipment used to produce LEU for nuclear fuel can also be used to produce HEU for weapons. Safeguards at an enrichment plant are the array of assurances and verification techniques that ensure uranium is only enriched to LEU, no undeclared LEU is produced, and no uranium is enriched to HEU or secretly diverted. There are several techniques for enriching uranium. The two most prevalent are gaseous diffusion, which uses older technology and requires a lot of energy, and gas centrifuge separation, which uses more advanced technology and is more energy efficient. Gaseous diffusion plants (GDPs) provide about 40% of current world enrichment capacity, but are being phased out as newer gas centrifuge enrichment plants (GCEPs) are constructed. Estimates of current and future enrichment capacity are always approximate, due to the constant upgrades, expansions, and shutdowns occurring at enrichment plants, largely determined by economic interests. Currently, the world enrichment capacity is approximately 53 million kg-separative work units (SWU) per year, with 22 million in gaseous diffusion and 31 million in gas centrifuge plants. Another 23 million SWU/year of capacity are under construction or planned for the near future, almost entirely using gas centrifuge separation. Other less-efficient techniques have also been used in the past, including electromagnetic and aerodynamic separations, but these are considered obsolete, at least from a commercial perspective. Laser isotope separation shows promise as a possible enrichment technique

  17. 76 FR 34103 - In the Matter of Areva Enrichment Services, LLC (Eagle Rock Enrichment Facility); Notice of...

    Science.gov (United States)

    2011-06-10

    .... 10-899-02-ML-BD01] In the Matter of Areva Enrichment Services, LLC (Eagle Rock Enrichment Facility...'' portion of this proceeding regarding the December 2008 application by AREVA Enrichment Services, LLC (AES... gas centrifuge uranium enrichment facility--denoted as the Eagle Rock Enrichment Facility (EREF)--in...

  18. Development of a fuzzy logic method to build objective functions in optimization problems: application to BWR fuel lattice design

    International Nuclear Information System (INIS)

    Martin-del-Campo, C.; Francois, J.L.; Barragan, A.M.; Palomera, M.A.

    2005-01-01

    In this paper we develop a methodology based on the use of the Fuzzy Logic technique to build multi-objective functions to be used in optimization processes applied to in-core nuclear fuel management. As an example, we selected the problem of determining optimal radial fuel enrichment and gadolinia distributions in a typical 'Boiling Water Reactor (BWR)' fuel lattice. The methodology is based on the use of the mathematical capability of Fuzzy Logic to model nonlinear functions of arbitrary complexity. The utility of Fuzzy Logic is to map an input space into an output space, and the primary mechanism for doing this is a list of if-then statements called rules. The rules refer to variables and adjectives that describe those variables and, the Fuzzy Logic technique interprets the values in the input vectors and, based on the set of rules assigns values to the output vector. The methodology was developed for the radial optimization of a BWR lattice where the optimization algorithm employed is Tabu Search. The global objective is to find the optimal distribution of enrichments and burnable poison concentrations in a 10*10 BWR lattice. In order to do that, a fuzzy control inference system was developed using the Fuzzy Logic Toolbox of Matlab and it has been linked to the Tabu Search optimization process. Results show that Tabu Search combined with Fuzzy Logic performs very well, obtaining lattices with optimal fuel utilization. (authors)

  19. A Guide to Job Enrichment and Redesign.

    Science.gov (United States)

    Cunningham, J. Barton; Eberle, Ted

    1990-01-01

    Describes job design alternatives--job enrichment, the job characteristics model, Japanese style management, and quality-of-worklife approaches. Focuses on the problems that human resources professionals may encounter when attempting to implement these approaches. (Author/JOW)

  20. Mercury enrichment in sediments of Amba estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Ram, A.; Rokade, M.A.; Zingde, M.D.

    of anthropogenic metal to the estuary. Geoaccumulation index and enrichment factor support Hg contamination of the estuarine sediment to a varying degree. Hg is not significantly correlated with TOC, Al, Fe and Mn in these sediments...

  1. Safety criteria of uranium enrichment plants

    International Nuclear Information System (INIS)

    Nardocci, A.C.; Oliveira Neto, J.M. de

    1994-01-01

    The applicability of nuclear reactor safety criteria applied to uranium enrichment plants is discussed, and a new criterion based on the soluble uranium compounds and hexafluoride chemical toxicities is presented. (L.C.J.A.). 21 refs, 4 tabs

  2. Management's Ecstasy and Disparity Over Job Enrichment

    Science.gov (United States)

    King, Albert S.

    1976-01-01

    A case study analyzing job enrichment schemes and manager expectations of increased productivity is presented. It was found that it was the managers' expectations of increased productivity, not the reorganization of work, that led to higher productivity. (EC)

  3. Safety aspects of gas centrifuge enrichment plants

    International Nuclear Information System (INIS)

    Hansen, A.H.

    1987-01-01

    Uranium enrichment by gas centrifuge is a commercially proven, viable technology. Gas centrifuge enrichment plant operations pose hazards that are also found in other industries as well as unique hazards as a result of processing and handling uranium hexafluoride and the handling of enriched uranium. Hazards also found in other industries included those posed by the use of high-speed rotating equipment and equipment handling by use of heavy-duty cranes. Hazards from high-speed rotating equipment are associated with the operation of the gas centrifuges themselves and with the operation of the uranium hexafluoride compressors in the tail withdrawal system. These and related hazards are discussed. It is included that commercial gas centrifuge enrichment plants have been designed to operate safely

  4. (+)- 10-camphorsulfonic acid and enrichment of enantiomeric

    Indian Academy of Sciences (India)

    WINTEC

    . The partially resolved enriched sample of (S,S)-(–)-2,3-diphenylpiperazine with 73% ee was purified to obtain samples of 97% ee using different achiral acids via the preparation of either homochiral or heterochiral hydrogen bonded.

  5. Boron isotopic enrichment by displacement chromatography

    International Nuclear Information System (INIS)

    Mohapatra, K.K.; Bose, Arun

    2014-01-01

    10 B enriched boron is used in applications requiring high volumetric neutron absorption (absorption cross section- 3837 barn for thermal and 1 barn for 1 MeV fast neutron). It is used in fast breeder reactor (as control rod material), in neutron counter, in Boron Neutron Capture Therapy etc. Owing to very small separation factor, boron isotopic enrichment is a complex process requiring large number of separation stages. Heavy Water Board has ventured in industrial scale production of 10 B enriched boron using Exchange Distillation Process as well as Ion Displacement Chromatography Process. Ion Displacement Chromatography process is used in Boron Enrichment Plant at HWP, Manuguru. It is based on isotopic exchange between borate ions (B(OH) 4 - ) on anion exchange resin and boric acid passing through resin. The isotopic exchange takes place due to difference in zero point energy of 10 B and 11 B

  6. Process for recovering water enriched with deuterium

    International Nuclear Information System (INIS)

    Mandel, H.

    1975-01-01

    By the process proposed herewith, enrichment of deuterium in water by cooling water recirculation through series-connection of several cooling ciruits in the form of columns is obtained. With this method, conventional, open-type cooling towers without special installations can be applied, which is an important advantage as compared with a formerly proposed single-stage process with specially designed, complicated cooling towers. Series-connection of the cooling towers is carried out in such a way that the circulating water of a certain cooling circuit, which has a corresponding output value of deuterium enrichment, is conveyed to a succeeding circuit where further enrichment is achieved. The water enriched with deuterium is removed from the last cooling circuit of the series while an amount of fresch water equivalent to the water removed or evaporated altogether is fed to the first circuit of the series. (RB) [de

  7. U.S. forms uranium enrichment corporation

    International Nuclear Information System (INIS)

    Seltzer, R.

    1993-01-01

    After almost 40 years of operation, the federal government is withdrawing from the uranium enrichment business. On July 1, the Department of Energy turned over to a new government-owned entity--the US Enrichment Corp. (USEC)--both the DOE enrichment plants at Paducah, Ky., and Portsmouth, Ohio, and domestic and international marketing of enriched uranium from them. Pushed by the inability of DOE's enrichment operations to meet foreign competition, Congress established USEC under the National Energy Policy Act of 1992, envisioning the new corporation as the first step to full privatization. With gross revenues of $1.5 billion in fiscal 1992, USEC would rank 275th on the Fortune 500 list of top US companies. USEC will lease from DOE the Paducah and Portsmouth facilities, built in the early 1950s, which use the gaseous diffusion process for uranium enrichment. USEC's stock is held by the US Treasury, to which it will pay annual dividends. Martin Marietta Energy Systems, which has operated Paducah since 1984 and Portsmouth since 1986 for DOE, will continue to operate both plants for USEC. Closing one of the two facilities will be studied, especially in light of a 40% world surplus of capacity over demand. USEC also will consider other nuclear-fuel-related ventures. USEC will produce only low-enriched uranium, not weapons-grade material. Indeed, USEC will implement a contract now being completed under which the US will purchase weapons-grade uranium from dismantled Russian nuclear weapons and convert it into low-enriched uranium for power reactor fuel

  8. Comparative proteomic assessment of matrisome enrichment methodologies

    Science.gov (United States)

    Krasny, Lukas; Paul, Angela; Wai, Patty; Howard, Beatrice A.; Natrajan, Rachael C.; Huang, Paul H.

    2016-01-01

    The matrisome is a complex and heterogeneous collection of extracellular matrix (ECM) and ECM-associated proteins that play important roles in tissue development and homeostasis. While several strategies for matrisome enrichment have been developed, it is currently unknown how the performance of these different methodologies compares in the proteomic identification of matrisome components across multiple tissue types. In the present study, we perform a comparative proteomic assessment of two widely used decellularisation protocols and two extraction methods to characterise the matrisome in four murine organs (heart, mammary gland, lung and liver). We undertook a systematic evaluation of the performance of the individual methods on protein yield, matrisome enrichment capability and the ability to isolate core matrisome and matrisome-associated components. Our data find that sodium dodecyl sulphate (SDS) decellularisation leads to the highest matrisome enrichment efficiency, while the extraction protocol that comprises chemical and trypsin digestion of the ECM fraction consistently identifies the highest number of matrisomal proteins across all types of tissue examined. Matrisome enrichment had a clear benefit over non-enriched tissue for the comprehensive identification of matrisomal components in murine liver and heart. Strikingly, we find that all four matrisome enrichment methods led to significant losses in the soluble matrisome-associated proteins across all organs. Our findings highlight the multiple factors (including tissue type, matrisome class of interest and desired enrichment purity) that influence the choice of enrichment methodology, and we anticipate that these data will serve as a useful guide for the design of future proteomic studies of the matrisome. PMID:27589945

  9. Modeling of Transients in an Enrichment Circuit

    International Nuclear Information System (INIS)

    Fernandino, Maria; Delmastro, Dario; Brasnarof, Daniel

    2003-01-01

    In the present work a mathematical model is presented in order to describe the dynamic behavior inside a closed enrichment loop, the latter representing a single stage of an uranium gaseous diffusion enrichment cascade.The analytical model is turned into a numerical model, and implemented through a computational code.Transients of two species separation were numerically analyzed, including setting times of each magnitude, behavior of each one of them during different transients, and redistribution of concentrations along the closed loop

  10. NRC licensing of uranium enrichment plants

    International Nuclear Information System (INIS)

    Moran, B.W.

    1991-01-01

    The US Nuclear Regulatory Commission (NRC) is preparing a rule making that establishes the licensing requirements for low-enriched uranium enrichment plants. Although implementation of this rule making is timed to correspond with receipt of a license application for the Louisiana Energy Services centrifuge enrichment plant, the rule making is applicable to all uranium enrichment technologies. If ownership of the US gaseous diffusion plants and/or atomic vapor laser isotope separation is transferred to a private or government corporation, these plants also would be licensable under the new rule making. The Safeguards Studies Department was tasked by the NRC to provide technical assistance in support of the rule making and guidance preparation process. The initial and primary effort of this task involved the characterization of the potential safeguards concerns associated with a commercial enrichment plant, and the licensing issues associated with these concerns. The primary safeguards considerations were identified as detection of the loss of special nuclear material, detection of unauthorized production of material of low strategic significance, and detection of production of uranium enriched to >10% 235 U. The primary safeguards concerns identified were (1) large absolute limit of error associated with the material balance closing, (2) the inability to shutdown some technologies to perform a cleanout inventory of the process system, and (3) the flexibility of some technologies to produce higher enrichments. Unauthorized production scenarios were identified for some technologies that could prevent conventional material control and accounting programs from detecting the production and removal of 5 kg 235 U as highly enriched uranium. Safeguards techniques were identified to mitigate these concerns

  11. Principles and techniques of uranium enrichment

    International Nuclear Information System (INIS)

    Frejacques, Claude; Mezin, Michel

    1975-01-01

    The main separation processes already used industrially or likely to be used before the end of century (gas diffusion, ultracentrifugation, laser, the nozzle process, a process developed in South Africa) are presented. Some data on the costs of the enrichment are clarified. The main characteristics of the enrichment market in which the Eurodif plant is called upon, on the expiration of five years, to take a foremost place are reported [fr

  12. A Resolution of the Paradox of Enrichment

    OpenAIRE

    Feng, Z. C.; Li, Y. Charles

    2011-01-01

    The paradox of enrichment was observed by M. Rosenzweig in a class of predator-prey models. Two of the parameters in the models are crucial for the paradox. These two parameters are the prey's carrying capacity and prey's half-saturation for predation. Intuitively, increasing the carrying capacity due to enrichment of the prey's environment should lead to a more stable predator-prey system. Analytically, it turns out that increasing the carrying capacity always leads to an unstable predator-p...

  13. Reducing enrichment of fuel for research reactors

    International Nuclear Information System (INIS)

    Kanda, Keiji; Matsuura, Shojiro.

    1980-01-01

    In research reactors, highly enriched uranium (HEU) is used as fuel for their purposes of operation. However, the United States strongly required in 1977 that these HEU should be replaced by low enrichment uranium (LEU) of 20% or less, or even in unavoidable cases, it should be replaced by medium enrichment uranium (MEU). INFCE (International Nuclear Fuel Cycle Evaluation) which started its activity just at that time decided to discuss this problem in the research reactor group of No. 8 sectional committee. Japan has been able to forward the work, taking a leading part in the international opinion because she has taken the countermeasures quickly. INFCE investigated the problem along the lines of policy that the possibility of reducing the degree of enrichment should be limited to the degree in which the core structures and equipments of research reactors will be modified as little as possible, and the change of fuel element geometry will be done within the permissible thermohydrodynamic capacity, and concluded that it might be possible in near future to reduce the degree of enrichment to about 45% MEU, while the reduction to 20% LEU might require considerable research, development and verification. On the other hand, the joint researches by Kyoto University and ANL (Argonne National Laboratory) and by Japan Atomic Energy Research Institute and ANL are being continued. IAEA has edited the guidebook (IAEA-TECDOC-233) for reducing the degree of enrichment for developing countries. (Wakatsuki, Y.)

  14. Environmental enrichment choices of shelter cats.

    Science.gov (United States)

    Ellis, J J; Stryhn, H; Spears, J; Cockram, M S

    2017-08-01

    Choices made by cats between different types of environmental enrichment may help shelters to prioritize how to most effectively enrich cat housing, especially when limited by space or funds. This study investigates the environmental enrichment use of cats in a choice test. Twenty-six shelter cats were kept singularly in choice chambers for 10days. Each chamber had a central area and four centrally-linked compartments containing different types of environmental enrichment: 1) an empty control, 2) a prey-simulating toy, 3) a perching opportunity, and 4) a hiding opportunity. Cat movement between compartments was quantitatively recorded using a data-logger. Enriched compartments were visited significantly more frequently during the light period than during the dark period. Cats spent a significantly greater percentage of time in the hiding compartment (median=55%, IQR=46) than in the toy compartment (median=2%, IQR=9), or in the empty control compartment (median=4%, IQR=4). These results provide additional evidence to support the value of a hiding box to cats housed in a novel environment, in that they choose hiding relative to other types of environmental enrichment. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Toward a predictive theory for environmental enrichment.

    Science.gov (United States)

    Watters, Jason V

    2009-11-01

    There have been many applications of and successes with environmental enrichment for captive animals. The theoretical spine upon which much enrichment work hangs largely describes why enrichment should work. Yet, there remains no clear understanding of how enrichment should be applied to achieve the most beneficial results. This lack of understanding may stem in part from the assumptions that underlie the application of enrichment by practitioners. These assumptions are derived from an understanding that giving animals choice and control in their environment stimulates their motivation to perform behaviors that may indicate a heightened state of well-being. Learning theory provides a means to question the manner in which these constructs are routinely applied, and converting learning theory's findings to optimality predictions suggests a particularly vexing paradox-that motivation to perform appears to be maintained best when acquiring a payoff for expressing the behavior is uncertain. This effect occurs even when the actual value of the payoff is the same for all schedules of certainty of payoff acquisition. The paradox can be resolved by invoking rewards of an alternative type, such as cognitive rewards, or through an understanding of how the average payoff changes with changes in the probability of reward. This model, with measures of the average change of the payoff, suggests testable scenarios by which practitioners can measure the quality of environmental uncertainty in enrichment programs.

  16. Oak Ridge National Laboratory's isotope enrichment program

    International Nuclear Information System (INIS)

    Tracy, J.G.; Aaron, W.C.

    1997-01-01

    The Isotope Enrichment Program (IEP) at Oak Ridge National Laboratory (ORNL) is responsible for the production and distribution of ∼225 enriched stable isotopes from 50 multi-isotopic elements. In addition, ORNL distributes enriched actinide isotopes and provides extensive physical- and chemical-form processing of enriched isotopes to meet customer requirements. For more than 50 yr, ORNL has been a major provider of enriched isotopes and isotope-related services to research, medical, and industrial institutions throughout the world. Consolidation of the Isotope Distribution Office (IDO), the Isotope Research Materials Laboratory (IRML), and the stable isotope inventories in the Isotope Enrichment Facility (IEF) have improved operational efficiencies and customer services. Recent changes in the IEP have included adopting policies for long-term contracts, which offer program stability and pricing advantages for the customer, and prorated service charges, which greatly improve pricing to the small research users. The former U.S. Department of Energy (DOE) Loan Program has been converted to a lease program, which makes large-quantity or very expensive isotopes available for nondestructive research at a nominal cost. Current efforts are being pursued to improve and expand the isotope separation capabilities as well as the extensive chemical- and physical-form processing that now exists. The IEF's quality management system is ISO 9002 registered and accredited in the United States, Canada, and Europe

  17. Boron nitride coated uranium dioxide and uranium dioxide-gadolinium oxide fuels

    Energy Technology Data Exchange (ETDEWEB)

    Gunduz, G [Department of Chemical Engineering, Middle East Technical Univ., Ankara (Turkey); Uslu, I; Tore, C; Tanker, E [Turkiye Atom Enerjisi Kurumu, Ankara (Turkey)

    1997-08-01

    Pure Urania and Urania-gadolinia (5 and 10%) fuels were produced by sol-gel technique. The sintered fuel pellets were then coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron trichloride and ammonia. The coated samples were sintered at 1600 K. The analyses under scanning electron microscope (SEM) showed a variety of BN structures, mainly platelike and rodlike structures were observed. Burnup calculations by using WIMSD4 showed that BN coated and gadolinia containing fuels have larger burnups than other fuels. The calculations were repeated at different pitch distances. The change of the radius of the fuel pellet or the moderator/fuel ratio showed that BN coated fuel gives the highest burnups at the present design values of a PWR. Key words: burnable absorber, boron nitride, gadolinia, CVT, nuclear fuel. (author). 32 refs, 14 figs.

  18. Boron nitride coated uranium dioxide and uranium dioxide-gadolinium oxide fuels

    International Nuclear Information System (INIS)

    Gunduz, G.; Uslu, I.; Tore, C.; Tanker, E.

    1997-01-01

    Pure Urania and Urania-gadolinia (5 and 10%) fuels were produced by sol-gel technique. The sintered fuel pellets were then coated with boron nitride (BN). This is achieved through chemical vapor deposition (CVD) using boron trichloride and ammonia. The coated samples were sintered at 1600 K. The analyses under scanning electron microscope (SEM) showed a variety of BN structures, mainly platelike and rodlike structures were observed. Burnup calculations by using WIMSD4 showed that BN coated and gadolinia containing fuels have larger burnups than other fuels. The calculations were repeated at different pitch distances. The change of the radius of the fuel pellet or the moderator/fuel ratio showed that BN coated fuel gives the highest burnups at the present design values of a PWR. Key words: burnable absorber, boron nitride, gadolinia, CVT, nuclear fuel. (author). 32 refs, 14 figs

  19. Operating experience with Exxon nuclear advanced fuel assembly and fuel cycle designs in PWRs

    International Nuclear Information System (INIS)

    Skogen, F.B.; Killgore, M.R.; Holm, J.S.; Brown, C.A.

    1986-01-01

    Exxon Nuclear Company (ENC) has achieved a high standard of performance in its supply of fuel reloads for both BWRs and PWRs, while introducing substantial innovations aimed at realization of improved fuel cycle costs. The ENC experience with advanced design features such as the bi-metallic spacer, the dismountable upper tie plate, natural uranium axial blankets, optimized water-to-fuel designs, annular pellets, gadolinia burnable absorbers, and improved fuel management scenarios, is summarized

  20. On-Line Enrichment Monitor for UF{sub 6} Gas Centrifuge Enrichment Plant

    Energy Technology Data Exchange (ETDEWEB)

    Ianakiev, K. D.; Boyer, B.; Favalli, A.; Goda, J. M.; Hill, T.; Keller, C.; Lombardi, M.; Paffett, M.; MacArthur, D. W.; McCluskey, C.; Moss, C. E.; Parker, R.; Smith, M. K.; Swinhoe, M. T. [Los Alamos National Laboratory, Los Alamos (United States)

    2012-06-15

    This paper is a continuation of the Advanced Enrichment Monitoring Technology for UF{sub 6} Gas Centrifuge Enrichment Plant (GCEP) work, presented in the 2010 IAEA Safeguards Symposium. Here we will present the system architecture for a planned side-by-side field trial test of passive (186-keV line spectroscopy and pressure-based correction for UF{sub 6} gas density) and active (186-keV line spectroscopy and transmission measurement based correction for UF{sub 6} gas density) enrichment monitoring systems in URENCO's enrichment plant in Capenhurst. Because the pressure and transmission measurements of UF{sub 6} are complementary, additional information on the importance of the presence of light gases and the UF{sub 6} gas temperature can be obtained by cross-correlation between simultaneous measurements of transmission, pressure and 186-keV intensity. We will discuss the calibration issues and performance in the context of accurate, on-line enrichment measurement. It is hoped that a simple and accurate on-line enrichment monitor can be built using the UF{sub 6} gas pressure provided by the Operator, based on online mass spectrometer calibration, assuming a negligible (a small fraction of percent) contribution of wall deposits. Unaccounted-for wall deposits present at the initial calibration will lead to unwanted sensitivity to changes in theUF{sub 6} gas pressure and thus to error in the enrichment results. Because the accumulated deposits in the cascade header pipe have been identified as an issue for Go/No Go measurements with the Cascade Header Enrichment Monitor (CHEM) and Continuous Enrichment Monitor (CEMO), it is important to explore their effect. Therefore we present the expected uncertainty on enrichment measurements obtained by propagating the errors introduced by deposits, gas density, etc. and will discuss the options for a deposit correction during initial calibration of an On-Line Enrichment Monitor (OLEM).

  1. The enriched chromium neutrino source for GALLEX

    International Nuclear Information System (INIS)

    Hartmann, F.X.; Hahn, R.L.

    1991-01-01

    The preparation and study of an intense source of neutrinos in the form of neutron irradiated materials which are enriched in Cr-50 for use in the GALLEX solar neutrino experiment are discussed. Chromyl fluoride gas is enriched in the Cr-50 isotope by gas centrifugation and subsequently converted to a very stable form of chromium oxide. The results of neutron activation analyses of such chromium samples indicate low levels of any long-lived activities, but show that short-lived activities, in particular Na-24, may be of concern. These results show that irradiating chromium oxide enriched in Cr-50 is preferable to irradiating either natural chromium or argon gas as a means of producing a neutrino source to calibrate the GALLEX detector. These results of the impurity level analysis of the enriched chromyl fluoride gas and its conversion to the oxide are also of interest to work in progress by other members of the Collaboration investigating an alternative conversion of the enriched gas to chromium metal. 35 refs., 12 figs., 5 tabs

  2. How is uranium supply affecting enrichment?

    International Nuclear Information System (INIS)

    Steve Kidd

    2007-01-01

    As a result of the enlivened uranium market, momentum has in turn picked up in the enrichment sector. What are the consequences of higher uranium prices? There is, of course, a link between uranium and enrichment supply to the extent that they are at least partial substitutes. On the enrichment supply side, the most obvious feature is the gradual replacement of the old gas diffusion facilities of Usec in the USA and EURODIF in France with more modern and economical centrifuge plants. Assuming Usec can overcome the financing and technical issues surrounding its plans, the last gas diffusion capacity should disappear around 2015 and the entire enrichment market should then be using centrifuges. On the commercial side, the key anticipated developments are mostly in Russia. Although there should still continue to be substantial quantities of surplus Russian HEU available for down blending in the period beyond 2013, it is now reasonable to expect that it will be mostly consumed by internal needs, to fuel Russian-origin reactors both at home and in export markets such as China and India. Finally, as a key sensitive area for the non-proliferation of nuclear weapons, the enrichment sector is likely to be a central point of the new international arrangements which must be developed to support a buoyant nuclear sector throughout this century.

  3. The Helikon technique for isotope enrichment

    International Nuclear Information System (INIS)

    Haarhoff, P.C.

    1976-11-01

    The separating element employed in the UCOR process for uranium enrichment has an enriched stream which is much smaller than the depleted stream. To deal with this small cut and to exploit the full potential of the process, a new cascade technique has been developed, the so-called helikon technique. It is based on the principle that an axial flow compressor can simultaneously compress a number of streams of different isotopic composition, which flow through it in parallel, without any significant mixing between them. The technique makes it possible to achieve the desired enrichment with a relatively small number of separating units, by making the best use of the high enrichment factor available. A further feature of the helikon technique is that a module yields an enrichment factor which is not constant, but can vary. In this way a cascade can be built up from modules of a fixed size, which is a great advantage when compared to conventional cascade arrangements where several unit sizes are required. A general theoretical treatment of the helikon technique is given and the similarity between helikon and conventional cascades is pointed out. Practical helikon cascades are subsequently discussed on the basis of the UCOR process

  4. Linking nutrient enrichment, sediment erodibility and biofilms

    Science.gov (United States)

    Conrad, B.; Mahon, R.; Sojka, S. L.

    2014-12-01

    Sediment movement in coastal lagoons affects nutrient flux and primary producer growth. Previous research has shown that sediment erodibility is affected by biofilm concentration and that growth of benthic organisms, which produce biofilm, is affected by nutrient enrichment. However, researchers have not examined possible links between nutrient addition and sediment erodibility. We manipulated nutrient levels in the water column of 16 microcosms filled with homogenized sediment from a shallow coastal lagoon and artificial seawater to determine the effects on biofilm growth, measured through chlorophyll a and colloidal carbohydrate concentrations. Erosion tests using a Gust microcosm were conducted to determine the relationship between sediment erodibility and biofilm concentration. Results show that carbohydrate levels decreased with increasing nutrient enrichment and were unrelated to chlorophyll concentrations and erodibility. The nutrient levels did not predictably affect the chlorophyll levels, with lower chlorophyll concentrations in the control and medium enrichment treatments than the low and high enrichment treatments. Controls on biofilm growth are still unclear and the assumed relationship between carbohydrates and erodibility may be invalid. Understanding how biofilms respond to nutrient enrichment and subsequent effects on sediment erodibility is essential for protecting and restoring shallow coastal systems.

  5. Profile of World Uranium Enrichment Programs-2009

    International Nuclear Information System (INIS)

    Laughter, Mark D.

    2009-01-01

    It is generally agreed that the most difficult step in building a nuclear weapon is acquiring fissile material, either plutonium or highly enriched uranium (HEU). Plutonium is produced in a nuclear reactor, whereas HEU is produced using a uranium enrichment process. Enrichment is also an important step in the civil nuclear fuel cycle, in producing low enriched uranium (LEU) for use as fuel for nuclear reactors to generate electricity. However, the same equipment used to produce LEU for nuclear reactor fuel can also be used to produce HEU for weapons. Safeguards at an enrichment plant are the array of assurances and verification techniques that ensure uranium is not diverted or enriched to HEU. There are several techniques for enriching uranium. The two most prevalent are gaseous diffusion, which uses older technology and requires a lot of energy, and gas centrifuge separation, which uses more advanced technology and is more energy efficient. Gaseous diffusion plants (GDPs) provide about 40% of current world enrichment capacity but are being phased out as newer gas centrifuge enrichment plants (GCEPs) are constructed. Estimates of current and future enrichment capacity are always approximate, due to the constant upgrades, expansions, and shutdowns occurring at enrichment plants, largely determined by economic interests. Currently, the world enrichment capacity is approximately 56 million kilogram separative work units (SWU) per year, with 22.5 million in gaseous diffusion and more than 33 million in gas centrifuge plants. Another 34 million SWU/year of capacity is under construction or planned for the near future, almost entirely using gas centrifuge separation. Other less-efficient techniques have also been used in the past, including electromagnetic and aerodynamic separations, but these are considered obsolete, at least from a commercial perspective. Laser isotope separation shows promise as a possible enrichment technique of the future but has yet to be

  6. Burnable absorber rod releasable latching structure

    International Nuclear Information System (INIS)

    Gjertsen, R.K.; Wilson, J.F.

    1987-01-01

    An elongated nuclear reactivity control member, a releasable latching structure useful for releasably attaching the control member at an end to a top nozzle adapter plate of a nuclear fuel assembly is described comprising: (a) a mounting body including an inner plug portion attached to the end of the control member and an outer end portion disposed axially outward from the inner plug portion and the end of the member; and (b) a spring latch disposed about the mounting body and being attached to the outer end portion. The spring latch has at least one latch finger extending toward the inner plug portion of the body and is movable toward and away from the body between an outer latching position in which the finger is adapted to engage a fuel assembly top nozzle adapter plate and retain the elongated member in a stationary relationship with respect to the adapter plate and an inner unlatching position in which the finger is adapted to disengage from the adapter plate and allow removal of the member from the adapter plate

  7. 31 CFR 540.308 - Low Enriched Uranium (LEU).

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Low Enriched Uranium (LEU). 540.308... OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.308 Low Enriched Uranium (LEU). The term low enriched...

  8. Development of on-line uranium enrichment monitor of gaseous UF6 for uranium enrichment plant

    International Nuclear Information System (INIS)

    Lu Xuesheng; Liu Guorong; Jin Huimin; Zhao Yonggang; Li Jinghuai; Hao Xueyuan; Ying Bin; Yu Zhaofei

    2013-01-01

    An on-line enrichment monitor was developed to measure the enrichment of UF 6 , flowing through the processing pipes in uranium enrichment plant. A Nal (Tl) detector was used to measure the count rates of the 185.7 keV γ-ray emitted from 235 U, and the total quantity of uranium was determined from thermodynamic characteristics of gaseous uranium hexafluoride. The results show that the maximum relative standard deviation is less than 1% when the measurement time is 120 s or more and the pressure is more than 2 kPa in the measurement chamber. Uranium enrichment of gaseous uranium hexafluoride in the output end of cascade can be monitored continuously by using the device. It should be effective for nuclear materials accountability verifications and materials balance verification at uranium enrichment plant. (authors)

  9. Uranium enrichment management review: summary of analysis

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    In May 1980, the Assistant Secretary for Resource Applications within the Department of Energy requested that a group of experienced business executives be assembled to review the operation, financing, and management of the uranium enrichment enterprise as a basis for advising the Secretary of Energy. After extensive investigation, analysis, and discussion, the review group presented its findings and recommendations in a report on December 2, 1980. The following pages contain background material on which that final report was based. This report is arranged in chapters that parallel those of the uranium enrichment management review final report - chapters that contain summaries of the review group's discussion and analyses in six areas: management of operations and construction; long-range planning; marketing of enrichment services; financial management; research and development; and general management. Further information, in-depth analysis, and discussion of suggested alternative management practices are provided in five appendices.

  10. Uranium enrichment management review: summary of analysis

    International Nuclear Information System (INIS)

    1981-01-01

    In May 1980, the Assistant Secretary for Resource Applications within the Department of Energy requested that a group of experienced business executives be assembled to review the operation, financing, and management of the uranium enrichment enterprise as a basis for advising the Secretary of Energy. After extensive investigation, analysis, and discussion, the review group presented its findings and recommendations in a report on December 2, 1980. The following pages contain background material on which that final report was based. This report is arranged in chapters that parallel those of the uranium enrichment management review final report - chapters that contain summaries of the review group's discussion and analyses in six areas: management of operations and construction; long-range planning; marketing of enrichment services; financial management; research and development; and general management. Further information, in-depth analysis, and discussion of suggested alternative management practices are provided in five appendices

  11. Method of deuterium isotope separation and enrichment

    International Nuclear Information System (INIS)

    Benson, S.W.

    1979-01-01

    A method is described for separating and enriching deuterium containing molecules comprising the steps of: providing a source of organic molecules containing a normal abundance of deuterium atoms, the organic molecules having a structural formula RX, in which R is an organic radical selected from ethyl, isopropyl, t-butyl and 3-cyclopentenyl, and in which X is selected from F, Cl, Br and OH, and wherein R represents 3-cyclopentenyl, X may additionally represent H; exposing the molecules to the radiation of at least one pulsed infrared laser source which has been specifically tuned and focussed to selectively decompose RX molecules containing deuterium to form an enriched olefin specie containing deuterium, and HX; and separating the deuterium enriched olefin specie from the undecomposed deuterium depleted RX molecules and HX. (author)

  12. Method of deuterium isotope separation and enrichment

    International Nuclear Information System (INIS)

    Benson, S.W.

    1978-01-01

    A method of separating deuterium, i.e., heavy hydrogen, from certain naturally occurring sources using tuned infrared lasers to selectively decompose specified classes of organic molecules (i.e., RX) into enriched molecular products containing deuterium atoms is described. The deuterium containing molecules are easily separated from the starting material by absorption, distillation or other simple chemical separation techniques and methods. After evaporation such deuterium containing molecules can be burned to form water with an enriched deuterium content or pyrolyzed to form hydrogen gas with an enriched deuterium content. The undecomposed molecules and the other reaction products which are depleted of their deuterium containing species can be catalytically treated, preferably using normal water, to restore the natural abundance of deuterium and such restored molecules can then be recycled

  13. A consideration on laser enrichment module

    International Nuclear Information System (INIS)

    Arisawa, Takashi; Shiba, Koreyuki

    1983-09-01

    Several problems are discussed for designing a simplified enrichment module based on Atomic Laser Isotope Separation Method, which involve the vaporization of metal, laser excitation, laser ionization and ion recovery. The conditions at which the consumed energy has the minimum value are obtained by calculating the specific energy consumption for producing unit amount of enriched products. It is found that there should be an appropriate relationship between the processing atomic density and the electrode gap in order to avoid the enrichment loss caused by the charge exchange during the ion recovery. Moreover it is also found that this relation depends on the electrode length measured along both the atomic beam direction and the laser beam direction. (author)

  14. Energy consumption of chemical uranium enrichment

    International Nuclear Information System (INIS)

    Miyake, T.; Takeda, K.; Obanawa, H.

    1987-01-01

    A quantitative study of chemical separation energy for enriching uranium-235 by the redox chromatography was conducted. Isotope exchange reactions between U 4+ -UO 2 2+ ions in the enrichment column are maintained by the redox reactions. The chemical separation energy is ultimately supplied by hydrogen and oxygen gas for regenerating redox agents. The redox energy for the isotope separation is theoretically predicted as a function of the dynamic enrichment factor observed in the chromatographic development of uranium adsorption band. Thermodynamic treatments of the equilibrium reactions implies and inverse redox reaction which can be enhanced by the chemical potential of the ion-exchange reaction of oxidant. Experimental results showed 30 to 90% recovery of the redox energy by the inverse reaction. These results will devise a simplified redox chromatography process where a number of columns in one module is reduced

  15. Method of deuterium isotope separation and enrichment

    International Nuclear Information System (INIS)

    Benson, S.W.

    1980-01-01

    A method of deuterium isotope separation and enrichment using infrared laser technology in combination with chemical processes for treating and recycling the unreacted and deuterium-depleted starting materials is described. Organic molecules of the formula RX (where R is an ethyl, isopropyl, t-butyl, or cyclopentenyl group and X is F, Cl, Br or OH) containing a normal abundance of hydrogen and deuterium are exposed to intense laser infrared radiation. An olefin containing deuterium (olefin D) will be formed, along with HX. The enriched olefin D can be stripped from the depleted stream of RX and HX, and can be burned to form enriched water or pyrolyzed to produce hydrogen gas with elevated deuterium content. The depleted RX is decomposed to olefins and RX, catalytically exchanged with normal water to restore the deuterium content to natural levels, and recombined to form RX which can be recycled. (LL)

  16. The evolution of the enriched uranium markets

    International Nuclear Information System (INIS)

    Arnaiz, J.; Moleres, C.; Tarin, F.

    2004-01-01

    This paper deals with the evolution of the enriched uranium component markets (uranium concentrates, conversion and enrichment), starting with the situation of historically low prices that occurred during 2000. The situation that has been reached as on December 2003, when the concentrates and conversion markets were 44% and 70% (current US$) respectively, and the enrichment prices 30%, higher, is analysed. Finally, the negative impact of the 90's depressed prices, due to abundant alternative sources of uranium components, on the primary production of all three components and, as a conclusion, the impact of the new situation on the transport logistics, and the need of appropriate economic conditions to make the future primary production sustainable, is commented. (Author)

  17. Nutrient enrichment increases mortality of mangroves.

    Directory of Open Access Journals (Sweden)

    Catherine E Lovelock

    Full Text Available Nutrient enrichment of the coastal zone places intense pressure on marine communities. Previous studies have shown that growth of intertidal mangrove forests is accelerated with enhanced nutrient availability. However, nutrient enrichment favours growth of shoots relative to roots, thus enhancing growth rates but increasing vulnerability to environmental stresses that adversely affect plant water relations. Two such stresses are high salinity and low humidity, both of which require greater investment in roots to meet the demands for water by the shoots. Here we present data from a global network of sites that documents enhanced mortality of mangroves with experimental nutrient enrichment at sites where high sediment salinity was coincident with low rainfall and low humidity. Thus the benefits of increased mangrove growth in response to coastal eutrophication is offset by the costs of decreased resilience due to mortality during drought, with mortality increasing with soil water salinity along climatic gradients.

  18. Stable isotope enrichment by thermal diffusion

    International Nuclear Information System (INIS)

    Vasaru, Gheorghe

    2003-01-01

    Thermal diffusion (TD) in both gaseous and liquid phase has been the subject of extensive experimental and theoretical investigations, especially after the invention by K. Clusius and G. Dickel of the thermal diffusion column, sixty years ago. This paper gives a brief overview of the most important applications and developments of this transport phenomenon for enrichment of 13 C and of some noble gases isotopes in our institute. The results of calculations of the transport coefficients H and K for a concentric tube type TD column, operated with methane as process gas, are presented. Static separation factor at equilibrium vs gas pressure has been calculated for various molecular models. The experimental separation factors for different gas pressure were found to be consistent with those calculated for the inverse power repulsion model and the Lennard-Jones model. The most important characteristics of a seven-stage cascade consisting of 19 TD columns of concentric tube type are given. This system has been constructed and successfully operated at a temperature of 673 K and produces an enrichment of methane of natural isotopic 13 C abundance, up to the concentration of 25% 13 CH 4 . Enrichment of the noble gases isotopes implies: - a . Enrichment of 20 Ne and 22 Ne in a eight-stage cascade consisting of 8 TD columns; - b. enrichment of 46 Ar in a seven-stage cascade consisting of TD columns and finally; - c. enrichment of 78 Kr and 86 Kr in a fifteen-stage cascade, consisting of 35 TD columns. For all these installations we have adopted TD columns of hot wire type (4 m in length), operated at a temperature of 1073 K. (author)

  19. Uranium enrichment by centrifuge in Japan

    International Nuclear Information System (INIS)

    Watanabe, T.; Murase, T.

    1977-01-01

    The demand for enriched uranium is on the increase with nuclear power capacity in which the LWR predominates and is estimated to exceed the supply from the present facilities in the world in less than ten years. Therefore, the basic strategy for enriched uranium is investigated on the following three-point long-range program in Japan: 1. To continue negotiations to extend the current allocation by the long-term contract; 2. To seek active participation in international enrichment projects; and 3. To make efforts to develop uranium enrichment technology and to construct inland facilities. On this basis, a vigorous development program of gas centrigue process for industrialization was launched out in 1972 as a national project. Ever since substantial progress in this field has been made and development works have been increased year after year. At present, a concrete plan of a pilot plant is taking shape. Up to now, several types of centrifuges were developed, of which some were completed as prototype models, and subjected to life tests and also to extensive earthquake-resistivity tests for the characteristics of Japanese geological condition. An enrichment plant is composed of so many centrifuges that the installation and piping system of centrifuges is an important factor which has an effect on plant economy and reliability. Two types of the experimental cascade were constructed in Japan. One has been in operation since 1973, and the other since 1975. Valuable empirical data have been accumulated on cascade characteristics, maintenance scheme and so on. It will be important for the coming plants to have a flexibility to escalation of labor and energy cost, or to variation of the separative work requirement and further. An economic prospect of centrifuge enrichment process is presented

  20. Report of the Subcommittee on Domestic Uranium Enrichment

    International Nuclear Information System (INIS)

    1981-01-01

    A report by the Subcommittee on Domestic Uranium Enrichment to the Atomic Energy Commission is described; which covers the procedure of the domestic uranium enrichment by centrifugal process up to the commercial production, reviewing the current situation in this field. Domestic uranium enrichment is important in the aspects of securing stable enrichment service, establishing sound fuel cycle, and others. As the future target, the production around the year 2000 is set at 3,000 tons SWU per year at least. The business of uranium enrichment, which is now developed in the Power Reactor and Nuclear Fuel Development Corporation, is to be carried out by private enterprise. The contents are as follows: demand and supply balance of uranium enrichment service, significance of domestic uranium enrichment, evaluation of centrifugal uranium enrichment technology, the target of domestic uranium enrichment, the policy of domestic uranium enrichment promotion. (J.P.N.)

  1. Enrichment situation outside the United States

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    Different enrichment technologies are briefly characterized which include gaseous diffusion, which is presently the production mainstay of the United States and France; the gaseous centrifuge which is the production plant for Urenco and the technology for future United States enrichment expansion; the aero-dynamic processes which include the jet nozzle (also known as the Becker process) and the fixed-wall centrifuge (also known as the Helikon process); chemical processes; laser isotope separation processes (also referred to in the literature as LIS); and plasma technology

  2. Phosphopeptide enrichment by immobilized metal affinity chromatography

    DEFF Research Database (Denmark)

    Thingholm, Tine E.; Larsen, Martin R.

    2016-01-01

    Immobilized metal affinity chromatography (IMAC) has been the method of choice for phosphopeptide enrichment prior to mass spectrometric analysis for many years and it is still used extensively in many laboratories. Using the affinity of negatively charged phosphate groups towards positively...... charged metal ions such as Fe3+, Ga3+, Al3+, Zr4+, and Ti4+ has made it possible to enrich phosphorylated peptides from peptide samples. However, the selectivity of most of the metal ions is limited, when working with highly complex samples, e.g., whole-cell extracts, resulting in contamination from...

  3. Isotopic enrichment in a plasma centrifuge

    International Nuclear Information System (INIS)

    Del Bosco, E.; Dallaqua, R.S.; Ludwig, G.O.; Bittencourt, J.A.

    1986-05-01

    A rotating fully ionized plasma column was produced in a vacuum-arc centrifuge. The apparatus is described and new results for the rotational velocity and isotope enrichment of carbon and metal plasmas are shown. The ion rotation velocity is derived from electrostatic probes measurents and from the azimuthal displacement of the material deposited behind of a narrow slit. The isotope enrichment is measured with a modified quadrupole mass spectrometer, which determines, in situ, the relative abundance of the isotopes at the end of the plasm column at various radil positions. (Author) [pt

  4. Uranium-enriched granites in Sweden

    International Nuclear Information System (INIS)

    Wilson, M.R.; Aakerblom, G.

    1980-01-01

    Granites with uranium contents higher than normal occur in a variety of geological settings in the Swedish Precambrian, and represent a variety of granite types and ages. They may have been generated by the anatexis of continental crust or processes occurring at a much greater depth. They commonly show enrichment in F, Sn, W and/or Mo. Only in one case is an important uranium mineralization thought to be directly related to a uranium-enriched granite, while the majority of epigenetic uranium mineralizations with economic potential are related to hydrothermal processes in areas where the bedrock is regionally uranium-enhanced. (author)

  5. Enrichment and Preservation of Architectural Knowledge

    DEFF Research Database (Denmark)

    Beetz, Jakob; Blümel, Ina; Dietze, Stefan

    2016-01-01

    In the context of the EU FP7 DURAARK project (2013–2016), inter-disciplinary methods, technologies and tools have been researched and developed, that support the Long Term Preservation of semantically enriched digital representations of built structures. The results of the research efforts include...... approaches of semi-automatically deriving building models from point cloud data sets acquired from laser scans and the integration and overlay of such representations with explicit Building Information Models (BIM). We introduce novel ways for the further semantic enrichment of such hybrid building models...

  6. Uranium enrichment: heading for the abyss

    International Nuclear Information System (INIS)

    Norman, C.

    1983-01-01

    This article discusses the federal government's $2.3 billion a year business enriching uranium for nuclear power plants which is heading toward a major crisis. Due to miscalculations by the Department of Energy, it is caught with billions of dollars of construction in progress just as projected demand for enriched uranium is decreasing. At the center of the controversy is the Gas Centrifuge Plant at Portsmouth, Ohio - estimated to cost $10 billion dollars. A review of how DOE got into this situation and how they plan to solve it is presented

  7. Slightly enriched uranium fuel for a PHWR

    International Nuclear Information System (INIS)

    Notari, C.; Marajofsky, A.

    1997-01-01

    An improved fuel element design for a PHWR using slightly enriched uranium fuel is presented. It maintains the general geometric disposition of the currently used in the argentine NPP's reactors, replacing the outer ring of rods by rods containing annular pellets. Power density reduction is achieved with modest burnup losses and the void volume in the pellets can be used to balance these two opposite effects. The results show that with this new design, the fuel can be operated at higher powers without violating thermohydraulic limits and this means an improvement in fuel management flexibility, particularly in the transition from natural uranium to slightly enriched uranium cycle. (author)

  8. Unattended safeguards instrumentation at centrifuge enrichment plants

    International Nuclear Information System (INIS)

    Smith, L. Eric; Lebrun, Alain R.; Labella, Rocco

    2014-01-01

    As global uranium enrichment capacity under international safeguards expands, the International Atomic Energy Agency (IAEA) is challenged to develop effective safeguards approaches at gaseous centrifuge enrichment plants, particularly high‑capacity plants, while working within budgetary constraints. New safeguards approaches should meet the high‑level verification objectives for such facilities (i.e., timely detection of: diversion of declared material, excess production beyond declared amounts, and production of enrichment levels higher than declared), but should also strive for efficiency advantages in implementation, for both the IAEA and operators. Under the Agency’s State- level approach to safeguards implementation, the Agency needs a flexible toolbox of technologies, allowing tailoring of safeguards measures for each individual enrichment facility. In this paper, the potential roles and development status for three different types of unattended measurement instrumentation are discussed. On‑Line Enrichment Monitors (OLEM) could provide continuous enrichment measurement for 100% of the declared gas flowing through unit header pipes. Unattended Cylinder Verification Stations (UCVS) could provide unattended verification of the declared uranium mass and enrichment of 100% of the cylinders moving through the plant, but also apply and verify an ‘NDA Fingerprint’ to preserve verification knowledge on the contents of each cylinder throughout its life in the facility. Sharing of the operator’s load cell signals from feed and withdrawal stations could count all cylinders introduced to the process and provide periodic monitoring of the uranium mass balance for in‑process material. The integration of load cell, OLEM and UCVS data streams offers the possibility for 100% verification of declared cylinder flow, and enables the periodic verification of the declared 235 U mass balance in the plant. These new capabilities would enhance the IAEA

  9. Enriched lithium collection from lithium plasma flow

    International Nuclear Information System (INIS)

    Karchevsky, A.I.; Laz'ko, V.S.; Muromkin, Y.A.; Pashkovsky, V.G.; Ustinov, A.L.; Dolgolenko, D.A.

    1994-01-01

    In order to understand the physical processes concerned with the selective heating by ion cyclotron resonance and with the subsequent collection of heated particles, experiments were carried out with the extraction of lithium samples, enriched with 6 Li isotopes. Probe and integral extractors allow to collect enriched Li at the end of the selective heating region. Surface density distribution on the collector and local isotopic content of lithium are measured, as a function of the screen height and the retarding potential. Dependence of the collected amount of lithium and of its isotopic content on the value of the magnetic field is also measured. 4 figs., 2 tabs., 5 refs

  10. Uranium enrichment services in the United States

    International Nuclear Information System (INIS)

    Jelinek, P.; Lenders, M.

    1994-01-01

    The United States of America is the world's largest market for uranium enrichment services. After the disintegration of the Soviet Union, Russian uranium is entering the world market on an increasing scale. The U.S. tries to protect its market and, in this connection, also the European market from excessive price drops by taking anti-dumping measures. In order to become more competitive, American companies have adapted modern enrichment techniques from Europe. European - U.S. joint ventures are to help, also technically and economically, to integrate military uranium, accumulating as a consequence of worldwide disarmament, into the commercial fuel cycle for the peaceful use of nuclear power. (orig.) [de

  11. Uranium enrichment. Industrial and commercial aspect

    International Nuclear Information System (INIS)

    Lamorlette, G.

    1983-01-01

    The uranium enrichment, a key stage in the fuel cycle of light-water nuclear power stations, applies sophisticated and protected techniques in installations on a very large scale. This article shows how there was a sudden change from a monopoly position in production to a severe competition in a market which is depressed today but offers good prospects for the future. It indicates how the enrichment industrialist have adapted themselves to the fluctuations of the demand, while safeguarding the reliability of the rendered service and the necessary security of supplies for the proper development of the nuclear electric power [fr

  12. 75 FR 10525 - In the Matter of: AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility) and All Other...

    Science.gov (United States)

    2010-03-08

    ...: AREVA Enrichment Services, LLC (Eagle Rock Enrichment Facility) and All Other Persons Who Seek or Obtain... for the Implementation of a Safeguards Information Program (Effective Immediately) I AREVA Enrichment... it to construct and operate a uranium enrichment facility in Bonneville County, Idaho. AES submitted...

  13. 77 FR 14838 - General Electric-Hitachi Global Laser Enrichment LLC, Commercial Laser-Based Uranium Enrichment...

    Science.gov (United States)

    2012-03-13

    ... Laser Enrichment LLC, Commercial Laser-Based Uranium Enrichment Facility, Wilmington, North Carolina... a license to General Electric-Hitachi Global Laser Enrichment LLC (GLE or the applicant) to authorize construction of a laser-based uranium enrichment facility and possession and use of byproduct...

  14. Low-enriched fuel particle performance review

    International Nuclear Information System (INIS)

    Homan, F.; Nabielek, H.; Yang, L.

    1978-08-01

    The available data on low-enriched (LEU) fuel particles were reviewed under the United States-Federal Republic of Germany Agreement. The most influential factors controlling the irradiation performance of LEU fuel particles were found to be plutonium transport, fission product transport, fuel particle mechanical performance and fuel particle chemical performande. (orig.) [de

  15. Low-enriched fuel particle performance review

    International Nuclear Information System (INIS)

    Homan, F.; Nabielek, H.; Yang, L.

    1978-08-01

    The available data on low-enriched uranium (LEU) fuel particles were reviewed under the United States-Federal Republic of Germany Agreement. The most influential factors controlling the irradiation performance of LEU fuel particles were found to be plutonium transport, fission product transport, fuel particle mechanical performance, and fuel particle chemical performance

  16. GRAN SASSO: Enriched germanium in action

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1991-12-15

    Two large crystals of carefully enriched germanium, one weighing 1 kilogram and the other 2.9 kilograms, and worth many millions of dollars, are being carefully monitored in the Italian Gran Sasso Laboratory in the continuing search for neutrinoless double beta decay.

  17. Isotope enrichment by photolysis on ordered surfaces

    International Nuclear Information System (INIS)

    Epling, G.A.; Florio, E.

    1981-01-01

    A surface was prepared as a micelle model which could be altered, by reacting trichlorododecylsilane with silica gel. Adsorption of dibenzyl ketone onto this surface followed by irradiation resulted in a recovered dibenzyl ketone enriched in 13 C. The plot of log S vs -log (1-f) had a slope of 1.66

  18. Isotope enrichment by photolysis on ordered surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Epling, G.A.; Florio, E.

    1981-03-11

    A surface was prepared as a micelle model which could be altered, by reacting trichlorododecylsilane with silica gel. Adsorption of dibenzyl ketone onto this surface followed by irradiation resulted in a recovered dibenzyl ketone enriched in /sup 13/C. The plot of log S vs -log (1-f) had a slope of 1.66. (DLC)

  19. Isotopic enrichment in a plasma centrifuge

    International Nuclear Information System (INIS)

    Del Bosco, E.; Dallaqua, R.S.; Ludwig, G.O.; Bittencourt, J.A.

    1987-01-01

    High rotational velocity and centrifugal isotopic separation of carbon in a vacuum-arc plasma centrifuge are presented. Enrichments of up to 390% for 13 C are measured at 6 cm radius with angular rotation frequencies in excess of 1.0 x 10 5 rad/s in an axial magnetic field of 0.12 T

  20. Drama in English: An Enriching Experience.

    Science.gov (United States)

    Geffen, Mitzi

    1998-01-01

    Examines the rationale behind using musical drama in English-as-a-Second-Language classes, explaining that it is an enjoyable experience that enriches students' English while they are relaxed, working as a team, and having fun with their imaginations. The article explains the process of putting on a play and evaluates the effect such a project had…

  1. GRAN SASSO: Enriched germanium in action

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Two large crystals of carefully enriched germanium, one weighing 1 kilogram and the other 2.9 kilograms, and worth many millions of dollars, are being carefully monitored in the Italian Gran Sasso Laboratory in the continuing search for neutrinoless double beta decay

  2. Genetic enrichment of cardiomyocytes derived from mouse ...

    African Journals Online (AJOL)

    Genetic enrichment of cardiomyocytes derived from mouse embryonic stem cells. WJ He, SC Li, LL Ye, H Liu, QW Wang, WD Han, XB Fu, ZL Chen. Abstract. Pluripotent embryonic stem cells (ESC) have the ability to differentiate into a variety of cell lineages in vitro, including cardiomyocytes. Successful applications of ...

  3. Recommendations based on semantically enriched museum collections

    NARCIS (Netherlands)

    Wang, Y.; Stash, N.; Aroyo, L.M.; Gorgels, P.; Rutledge, L.W.; Schreiber, G.

    2008-01-01

    This article presents the CHIP demonstrator1 for providing personalized access to digital museum collections. It consists of three main components: Art Recommender, Tour Wizard, and Mobile Tour Guide. Based on the semantically enriched Rijksmuseum Amsterdam2 collection, we show how Semantic Web

  4. Review of environmental enrichment for broiler chickens

    NARCIS (Netherlands)

    Riber, A.B.; De Weerd, Van H.A.; Jong, De I.C.; Steenfeldt, S.

    2018-01-01

    Welfare problems are commonly found in both conventional and organic production of broiler chickens. In order to reduce the extent of welfare problems, it has been suggested to provide stimulating, enriched environments. The aim of the present paper is to provide a review of the effect on behavior

  5. Feasibility of uranium enrichment in Australia

    International Nuclear Information System (INIS)

    1979-10-01

    The Council considered that provided the balance between costs and markets was found to be acceptable, there was no valid reason against the Government proceeding with a study on the feasibility of, and perhaps participating in the establishment of a commercial uranium enrichment industry in Australia. Areas covered include technical expertise and industrial structure in Australia, environmental aspects and safeguards

  6. 21 CFR 137.165 - Enriched flour.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Enriched flour. 137.165 Section 137.165 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... riboflavin, 24 milligrams of niacin, 0.7 milligrams of folic acid, and 20 milligrams of iron. (b) It may...

  7. Gas Enrichment at Liquid-Wall Interfaces

    NARCIS (Netherlands)

    Dammer, S.M.; Lohse, Detlef

    2006-01-01

    Molecular dynamics simulations of Lennard-Jones systems are performed to study the effects of dissolved gas on liquid-wall and liquid-gas interfaces. Gas enrichment at walls, which for hydrophobic walls can exceed more than 2 orders of magnitude when compared to the gas density in the bulk liquid,

  8. Metacognitive Enrichment for Community College Students

    Science.gov (United States)

    Wyre, Steven H.

    2012-01-01

    Recent research was conducted to explore how introducing metacognitive enrichment into courses containing implicit or explicit critical thinking goals would affect the students' personal epistemological maturity. At the beginning of a fall semester at a moderate sized community college in the southeastern United States, 733 students were divided…

  9. Status report on uranium enrichment associates

    International Nuclear Information System (INIS)

    Langley, R.A. Jr.; O'Donnell, A.J.; Garrett, G.A.

    1977-01-01

    Uranium Enrichment Associates (UEA) had as its priority project financing, an approach in which the total project is financially self-liquidating. UEA worked with financial institutions to define the combination of assurances and guarantees required by lenders in order to provide the required debt funding. UEA's assets against which the debt liability for the plant would be balanced would be the facilities under construction and the equipment on order. On the customer side, there was major concern on the part of the utilities of whether private industry would be able to complete and operate the plant owing to many of the same possibilities which concerned financial institutions. The disparity between the conditions under which financing could be obtained and the terms acceptable to utilities was a significant element in EUA's choice of process to use for its enrichment plants. UEA's technical staff then began to parallel conceptual designs of gaseous diffusion and gas cenrifuge plants. UEA negotiated with ERDA on the terms of a Cooperative Arrangement, within the provisions of the NFAA, providing the minimum conditions necessary to obtain financing and contracts with utilities for enrichment sources. The UEA plant has several features different from the ERDA plants. The UEA plant used only two basic stage sizes. The UEA design employed four main process buildings. The partners in UEA have mutually agreed to follow the private uranium enrichment project to a logical conclusion. 6 figures

  10. PROTEIN ENRICHMENT OF SPENT SORGHUM RESIDUE USING ...

    African Journals Online (AJOL)

    BSN

    The optimum concentration of spent sorghum for protein enrichment with S. cerevisiae was 7.Sg/100 ml. Th.: protein ... production of single sell protein using Candida utilis and cassava starch effluem as substrate. ... wastes as substrates, Kluyveromyces fragilis and milk whey coconut water as substrate (Rahmat et al.,. 1995 ...

  11. Challenges when developing omega-3 enriched foods

    DEFF Research Database (Denmark)

    Jacobsen, Charlotte

    2010-01-01

    the influence of important factors such as oil quality, delivery systems for omega-3 fatty acids, processing conditions, composition of the food matrix on lipid oxidation in different omega-3 enriched foods (milk, yoghurt, mayonnaise and mayonnaise-based salads, dressing, energy bar and fish paté). Moreover...

  12. Uranium enrichment management review. Final report

    International Nuclear Information System (INIS)

    Ellett, J.D.; Rieke, W.B.; Simpson, J.W.; Sullivan, P.E.

    1980-01-01

    The uranium enrichment enterprise of the US Department of Energy (DOE) provides enriched nuclear fuel for private and government utilities domestically and abroad. The enterprise, in effect, provides a commercial service and represents a signficant business operation within the US government: more than $1 billion in revenues annually and future capital expenditures estimated at several billions of dollars. As a result, in May 1980, the Assistant Secretary for Resource Applications within DOE requested that a group of experienced business executives be assembled to review the operation, financing, and management of the uranium enrichment enterprise as a basis for advising the Secretary of Energy. The review group was specifically asked to focus on the management activities to which sound business practices could be applied. The group developed findings and recommendations in six areas: management of operations and construction; long-range planning; marketing of enrichment services; financial management; research and development; and general management. The chapters of this report present first the management review group's recommendations in the six areas evaluated and then the findings and issues in each area. An appendix provides the group's calendar of meetings. A list of major reference sources used in the course of the study is also included. 12 references

  13. Books to Expand and Enrich Experiences.

    Science.gov (United States)

    Winfield, Evelyn T.

    1983-01-01

    Books are briefly described that parents can read and discuss with their children to enrich travel and cultural activities. Books on the nation's capital city, the Liberty Bell, the Statue of Liberty, architecture, zoos, dinosaurs, and other subjects are included. (PP)

  14. Laser enrichment: a new path to proliferation

    International Nuclear Information System (INIS)

    Casper, B.M.

    1977-01-01

    The use of lasers to obtain enriched uranium is an easier and cheaper method than methods currently in use. The immediate concern is that it could promote easy access to nuclear weapons by countries that do not presently have them. Mr. Casper feels that the U.S. government is working against itself; while the State Department is seeking to block one path to proliferation, ERDA laboratories are developing new technology that could open another. The proliferation implications have not been factored in a serious way into the decisions to proceed with this research. It is also clear that the United States does not now have a comprehensive policy that deals with all potentially important paths to proliferation, including laser enrichment. Mr. Casper states that there is still time to stop and consider whether laser enrichment should be developed, in light of its broader consequences. But this will not happen if the decisions are left exclusively in the hands of those promoting the technology, the author says. It is just this sort of situation that prompted the creation of several government institutions to provide independent assessments of new technologies. The Office of Technology Assessment, the Nuclear Regulatory Commission, and the Arms Control and Disarmament Agency all have the authority to intervene. Laser enrichment provides a good test of these institutions and of the viability of the concept of technology assessment. The status, benefits and risks, and the policy needed on laser research are discussed

  15. Topical papers on uranium conversion and enrichment

    International Nuclear Information System (INIS)

    Uranium conversion and enrichment are discussed in 5 papers by representatives of the USA, Great Britain and Switzerland. The state of the art is reviewed, and future prospects are given. Supply assurance is directly related to the necessary production capacities and the supply agreements

  16. Isotopically enriched structural materials in nuclear devices

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, L.W.G., E-mail: Lee.Morgan@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Shimwell, J. [CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom); Department of Physics and Astronomy, University of Sheffield, Hicks Building, Hounsfield Road, Sheffield S3 7RH (United Kingdom); Gilbert, M.R. [CCFE, Culham Science Centre, Abingdon, Oxfordshire OX14 3DB (United Kingdom)

    2015-01-15

    Highlights: • C-B analysis of isotopic enrichment of structural materials is presented. • Some, previously, prohibited elements could be used as alloying elements in LAM's. • Adding enriched molybdenum and nickel, to EUROFER, could increase availability. • Isotope enrichment for EUROFER could be cost-effective. • Isotopically enriching copper, in CuCrZr, can reduce helium production by 50%. - Abstract: A large number of materials exist which have been labeled as low activation structural materials (LAM). Most often, these materials have been designed in order to substitute-out or completely remove elements that become activated and contribute significantly to shut-down activity after being irradiated by neutrons in a reactor environment. To date, one of the fundamental principles from which LAMs have been developed is that natural elemental compositions are the building blocks of LAMs. Thus, elements such as Co, Al, Ni, Mo, Nb, N and Cu that produce long-lived decay products are significantly reduced or removed from the LAM composition. These elements have an important part to play in the composition of steels and the removal/substitution can have a negative impact on materials properties such as yield stress and fracture toughness. This paper looks in more detail at whether using isotopic selection of the more mechanically desirable, but prohibited due to activation, elements can improve matters. In particular, this paper focuses on the activation of Eurofer. Carefully chosen isotopically enriched elements, which are normally considered to be on the prohibited element list, are added to EUROFER steel as potential alloying elements. The EUROFER activation results show that some prohibited elements can be used as alloying elements in LAM steels, providing the selected isotopes do not have a significant impact on waste disposal rating or shut-down dose. The economic implications of isotopically enriching elements and the potential implications for

  17. Enrichment measurement in TRIGA type fuels

    International Nuclear Information System (INIS)

    Aguilar H, F.; Mazon R, R.

    2001-05-01

    The Department of Energy of the United States of North America, through the program 'Idaho Operations Nuclear Spent Fuel Program' of the Idaho National Engineering and Environmental Laboratory (INEEL), in Idaho Falls; Idaho USA, hires to Global Technologies Inc. (GTI) to develop a prototype device of detection enrichment uranium (DEU Detection of Enrichment of Uranium) to determine quantitatively the enrichment in remainder U-235 in a TRIGA fuel element at the end of it useful life. The characteristics of the prototype developed by GTI are the following ones: It allows to carry out no-destructive measurements of TRIGA type fuel. Easily transportable due to that reduced of it size. The determination of the enrichment (in grams of U-235) it is obtained with a precision of 5%. The National Institute of Nuclear Research (ININ), in its facilities of the Nuclear Center of Mexico, it has TRIGA type fuel of high and low enrichment (standard and FLIP) fresh and with burnt, it also has the infrastructure (hot cells, armor-plating of transport, etc) and qualified personnel to carry out the necessary maneuvers to prove the operation of the DEU prototype. For this its would be used standard type fuel elements and FLIP, so much fresh as with certain burnt one. In the case of the fresh fuels the measurement doesn't represent any risk, the fuels before and after the measurement its don't contain a quantity of fission products that its represent a radiological risk in its manipulation; but in the case of the fuels with burnt the handling of the same ones represents an important radiological risk reason why for its manipulation it was used the transport armor-plating and the hot cells. (Author)

  18. A proposal for a unified fuel thermal conductivity model available for UO{sub 2}, (U-Pu)O{sub 2} and UO{sub 2}-GD{sub 2}O{sub 3} PWR fuel

    Energy Technology Data Exchange (ETDEWEB)

    Baron, D [Electrice de France, Moret-sur-Loing (France); Couty, J C [Electricite de France (EDF), 69 - Villeurbanne (France)

    1997-08-01

    In order to cope with the current fuel management targets which are focussed on higher discharge burnups, initial {sup 235}U fuel enrichments have been increased from 3.25% to 4%. To avoid an increase in boron concentration in the primary circuit, Gadolinium is used as a burnable poison, spread in the uranium oxide matrix of selected rods, in order to absorb the initial reactivity excess. Obviously, fuel thermal conductivity is affected when introducing any stranger element. Previously, the EDF thermomechanical code provided two different models to simulate the fuel thermal conductivity: one available for UO{sub 2} and (U-Pu)O{sub 2} fuels, the other for Gadolinia fuels, depending on the calculations to be done. No effect of the initial fuel stoichiometry was taken into account in the second model. That situation suggested the development of a unified model available for any fuels presently loaded in the EDF PWR reactors. This paper deals with the choice of the formulation, the data base used and the methodology applied for parameter fitting. Results in terms of measured versus predicted evaluation are then discussed. (author). 11 refs, 5 figs.

  19. Guidebook on quality control of mixed oxides and gadolinium bearing fuels for light water reactors

    International Nuclear Information System (INIS)

    1991-02-01

    Under the coverage of an efficient quality assurance system, quality control in nuclear fuel fabrication is an essential element to assure the reliable performance of all its components in service. Incentives to increase fuel performance, by extending reactor cycles or achieving higher burnups and, in some countries to use recycled plutonium in light water reactors (LWRs) necessitated the development of new types of fuels. In the first case, due to higher uranium enrichments, a burnable neutron absorber was integrated to the fuel pellets. Gadolinia was found to form a solid solution with Uranium dioxide and, to present a burnup rate which matches fissile uranium depletion. (U,Gd)O 2 fuels which have been successfully used since the seventies, in boiling water reactors have more recently found an increased utilization, in pressurized water reactors. This amply justifies the publication of this TECDOC to encourage authorities, designers and manufacturers of these types of fuel to establish a more uniform, adapted and effective system of control, thus promoting improved materials reliability and good performance in advanced fuel for light water reactors. The Guidebook is subdivided into four chapters written by different authors. A separate abstract was prepared for each of these chapters. Refs, figs and tabs

  20. CEA contribution to power plant operation with high burnup level

    International Nuclear Information System (INIS)

    1981-03-01

    High level burnup in PWR leads to investigate again the choices carried out in the field of fuel management. French CEA has studied the economic importance of reshuffling technique, cycle length, discharge burnup, and non-operation period between two cycles. Power plants operators wish to work with increased length cycles of 18 months instead of 12. That leads to control problems because the core reactivity cannot be controlled with the only soluble boron: moderator temperature coefficient must be negative. With such cycles, it is necessary to use burnable poisons and for economic reasons with a low penalty in end of cycle. CEA has studied the use of Gd 2 O 3 mixed with fuel or with inert element like Al 2 O 3 . Parametric studies of specific weights, efficacities relatively to the fuel burnup and the fuel enrichment have been carried out. Particular studies of 1 month cycles with Gd 2 O 3 have shown the possibility to control power distribution with a very low reactivity penalty in EOC. In the same time, in the 100 MW PWR-CAP, control reactivity has been made with large use of gadolinia in parallel with soluble boron for the two first cycles

  1. Enrichment technology. Dependable vendor of gas centrifuges; Enrichment Technology. Zuverlaessiger Lieferant von Gaszentrifugen

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2011-10-15

    Enrichment Technology is an innovative, high-tech company that develops, manufactures and installs gas centrifuges for enriching uranium. In addition, Enrichment Technology designs enrichment plants that use gas centrifuge technology. This technology offers the most efficient and cost-effective method for enriching uranium yet: high-performance, safe technology that dominates the market with a global share of 45 percent. A determining factor in Enrichment Technology's success is its mission: supplying its customers with safe, reliable technology. Production of the centrifuges requires versatile know-how and collaboration between different departments as well as interdisciplinary teams at the various sites. More than 2000 operators at 8 sites in 5 countries contribute their individual knowledge and personal skills in order to produce this exceptional technology. The head office is in Beaconsfield near London and the operational headquarters are in Almelo in the Netherlands. There are other sites in Germany (Juelich und Gronau), Great Britain (Capenhurst) as well as project sites in the USA and France. Capenhurst is where experienced engineers design new enrichment plants and organise their construction. Centrifuge components are manufactured in Almelo and Juelich, while the pipework needed to connect up the centrifuges is produced at the site in Gronau. In Juelich, highly qualified scientists in interdisciplinary teams are continuously researching ways of improving the current centrifuges. Communication between specialists in the fields of chemistry, physics and engineering forms the basis for the company's success and the key to extending this leading position in the global enrichment market. (orig.)

  2. Synthesis of 15N-enriched fertilizers. Pt. II. Synthesis of 15N-enriched urea

    International Nuclear Information System (INIS)

    Bondassolli, J.A.; Trivelin, P.C.O.; Mortatti, J.; Victoria, R.L.

    1988-01-01

    The results of studies on the production of 15 N-urea through the reaction between 15 N-enriched anhidrous ammonia, carbon monoxide and sulfur, using hydrogen sulfite as a auto catalizers and methyl alcohol as a liquid reaction medium is presented. The influence of the quantities of reagents on final yield of synthesised urea were studied. Analysis of the cost of 5 Atoms % 15 N-enriched urea were made. (M.A.C.) [pt

  3. From high enriched to low enriched uranium fuel in research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Van Den Berghe, S.; Leenaers, A.; Koonen, E.; Moons, F.; Sannen, L. [Nuclear Materials Science Institute, SCK.CEN, Boeretang 200, B-2400 Mol (Belgium)

    2010-07-01

    Since the 1970's, global efforts have been going on to replace the high-enriched (>90% {sup 235}U), low-density UAlx research reactor fuel with high-density, low enriched (<20% {sup 235}U) replacements. This search is driven by the attempt to reduce the civil use of high-enriched material because of proliferation risks and terrorist threats. American initiatives, such as the Global Threat Reduction Initiative (GTRI) and the Reduced Enrichment for Research and Test Reactors (RERTR) program have triggered the development of reliable low-enriched fuel types for these reactors, which can replace the high enriched ones without loss of performance. Most success has presently been obtained with U{sub 3}Si{sub 2} dispersion fuel, which is currently used in many research reactors in the world. However, efforts to search for a replacement with even higher density, which will also allow the conversion of some high flux research reactors that currently cannot change to U{sub 3}Si{sub 2} (eg. BR2 in Belgium), have continued and are for the moment mainly directed towards the U(Mo) alloy fuel (7-10 w% Mo). This paper provides an overview of the past efforts and presents the current status of the U(Mo) development. (authors)

  4. From high enriched to low enriched uranium fuel in research reactors

    International Nuclear Information System (INIS)

    Van Den Berghe, S.; Leenaers, A.; Koonen, E.; Moons, F.; Sannen, L.

    2010-01-01

    Since the 1970's, global efforts have been going on to replace the high-enriched (>90% 235 U), low-density UAlx research reactor fuel with high-density, low enriched ( 235 U) replacements. This search is driven by the attempt to reduce the civil use of high-enriched material because of proliferation risks and terrorist threats. American initiatives, such as the Global Threat Reduction Initiative (GTRI) and the Reduced Enrichment for Research and Test Reactors (RERTR) program have triggered the development of reliable low-enriched fuel types for these reactors, which can replace the high enriched ones without loss of performance. Most success has presently been obtained with U 3 Si 2 dispersion fuel, which is currently used in many research reactors in the world. However, efforts to search for a replacement with even higher density, which will also allow the conversion of some high flux research reactors that currently cannot change to U 3 Si 2 (eg. BR2 in Belgium), have continued and are for the moment mainly directed towards the U(Mo) alloy fuel (7-10 w% Mo). This paper provides an overview of the past efforts and presents the current status of the U(Mo) development. (authors)

  5. Enriched uranium recovery at Los Alamos

    International Nuclear Information System (INIS)

    Herrick, C.C.

    1984-01-01

    Graphite casting scrap, fuel elements and nongraphite combustibles are calcined to impure oxides. These materials along with zircaloy fuel elements and refractory solids are leach-dissolved separately in HF-HNO 3 acid to solubilize the contained enriched uranium. The resulting slurry is filtered and the clear filtrate (to which mineral acid solutions bearing enriched uranium may be added) are passed through solvent extraction. The solvent extraction product is filtered, precipitated with H 2 O 2 and the precipitate calcined to U 3 O 8 . Metal is made from U 3 O 8 by conversion to UO 2 , hydrofluorination and reduction to metal. Throughput is 150 to 900 kg uranium per year depending on the type of scrap

  6. Simulating Isotope Enrichment by Gaseous Diffusion

    Science.gov (United States)

    Reed, Cameron

    2015-04-01

    A desktop-computer simulation of isotope enrichment by gaseous diffusion has been developed. The simulation incorporates two non-interacting point-mass species whose members pass through a cascade of cells containing porous membranes and retain constant speeds as they reflect off the walls of the cells and the spaces between holes in the membranes. A particular feature is periodic forward recycling of enriched material to cells further along the cascade along with simultaneous return of depleted material to preceding cells. The number of particles, the mass ratio, the initial fractional abundance of the lighter species, and the time between recycling operations can be chosen by the user. The simulation is simple enough to be understood on the basis of two-dimensional kinematics, and demonstrates that the fractional abundance of the lighter-isotope species increases along the cascade. The logic of the simulation will be described and results of some typical runs will be presented and discussed.

  7. IAEA statement on Iranian enrichment announcement

    International Nuclear Information System (INIS)

    2010-01-01

    Full text: The following is a statement attributable to IAEA Spokesperson Gill Tudor: 'The IAEA can confirm that it has received a letter from the Atomic Energy Organization of Iran (AEOI) on 8 February 2010, in which the AEOI informed the Agency that production of less than 20% enriched uranium is being foreseen at the Pilot Fuel Enrichment Plant at Natanz for fuel for the Tehran Research Reactor'. 'IAEA Director General Yukiya Amano noted with concern this decision, as it may affect, in particular, ongoing international efforts to ensure the availability of nuclear fuel for the Tehran Research Reactor.' 'The Director General reiterated the Agency's readiness to play an intermediary role on the issue of the Tehran Research Reactor.' (IAEA)

  8. Market implications of advanced enrichment techniques

    International Nuclear Information System (INIS)

    Rougeau, J.-P.

    1987-01-01

    The only commercial outlet for uranium is for nuclear reactors and the uranium market will be closely linked to the nuclear power market for the forseeable future. Any production cost saving in the uranium cycle clearly, therefore, increases the chances for world-wide expansion of the nuclear industry. Thus, although there is overcapacity in enrichment, development of cheaper, new or more efficient established techniques, is important. The atomic vapour laser isotope separation process is considered and discussed against this background. Separative work units are explained for this technique. The problems of integrating laser isotope separation into the fuel cycle are discussed. The effects on the amount of natural uranium required for different recycling strategies, and for different laser tails assay and time schedules are illustrated. Over the next twenty years laser-based enrichment will have an important effect on the fuel cycle industry. COGEMA is expected to play a part in developing these new techniques. (U.K.)

  9. Uranium enrichment: an activity for the riches

    International Nuclear Information System (INIS)

    Mundim, S.G.

    1985-01-01

    The United States in the first place, the European countries next, have begun to maintain strict control of the technology transfer of the methods of enrichment, helped largely by the International Atomic Energy Agency which creates additional obstacles with is so-called 'safeguards'. So that it can possess a complete energy cycle, Brazil needs to have access to the techniques of enrichment. The methods are many and still extremely costly. Committed to signing a risk contract with Germany in the scope of its nuclear treaty with the intention of implementing here the jetcentrofuge method, Brazil should, nevertheless, make an effort to cause to emerge from its laboratories a new procedure which would permit it to become independent in this sector. (Author) [pt

  10. Progress in ultra-centrifuge enrichment technology

    International Nuclear Information System (INIS)

    Paul Dawson

    2006-01-01

    Urenco have undertaken a continuous development programme in centrifuge technology for over 35 years. This has seen development from sub-critical machines in the mid 1970's through to the company's world leading TC12 supercritical centrifuge, which has been deployed on a large-scale basis over the last decade. The latest centrifuge to emerge from this programme is Urenco's sixth generation centrifuge, the TC21, which will be commercially deployed from mid-2007 onwards. In recent times Urenco has vested its centrifuge technology in Enrichment Technology Company (ETC) as a vehicle to enable the use of this advanced technology by other operators for commercial purposes. This paper reviews why Urenco and ETC believe this technology represents the best choice for creating new global commercial enrichment capacity and its future development prospects. (author)

  11. Fair value enrichment pricing: is it fair

    International Nuclear Information System (INIS)

    1978-01-01

    The Atomic Energy Act of 1954, as amended (Public Law 83-702), requires the Department of Energy to recover all costs for its enrichment activities over a reasonable period of time. The proposed legislation would allow the Department to recover its costs plus a percentage of these costs. Six major factors are examined to determine whether the legislation should be adopted: What effect will the legislation have on the prices paid by ultimate consumers of electricity; will the increase in price resulting from the legislation help promote the establishment of a private uranium enrichment industry; how will the price increase impact on the administration's nuclear non-proliferation goals; what additional revenues will be generated from domestic and foreign customers; should the United States continue to perpetuate a subsidy to the U.S. nuclear industry; what effect, if any, will the new price have on the U.S. supply and demand situation for energy

  12. Uranium enrichment activities: the SILVA program

    International Nuclear Information System (INIS)

    Guyot, J.; Cazalet, J.; Camarcat, N.; Figuet, J.

    1994-01-01

    Through its commitment to a nuclear electricity generation policy, France holds today a specific position in the uranium enrichment market thanks to the modern multinational EURODIF gaseous diffusion plant. France has, altogether, a long-term goal in developing SILVA, a laser uranium enrichment process, based on the selective photo-ionization of U-235. After reviewing the fundamentals of SILVA (the laser system with copper vapor lasers and dye lasers and the separator system), a description of the general organization of the R and D program is provided going through basic research, subsystems assessment, production demonstrations and simulations (with the LACAN code), plant design and economics. The general schedule of SILVA is outlined, leading to the possible construction of a commercial plant. 7 figs., 11 refs

  13. Enrichment of high ammonia tolerant methanogenic culture

    DEFF Research Database (Denmark)

    Fotidis, Ioannis; Karakashev, Dimitar Borisov; Proietti, Nicolas

    Ammonia is the major toxicant in full scale anaerobic digesters of animal wastes which are rich in proteins and/or urea, such as pig or poultry wastes. Ammonia inhibition decreases methane production rates, increases volatile fatty acids concentration and leads to economic losses for the biogas...... was derived from a full scale biogas reactor (Hashøj, Denmark), fed with 75% animal manure and 25% food industries organic waste. Basal anaerobic medium was used for the enrichment along with sodium acetate (1 g HAc L-1) as a carbon source. Fluorescence insitu hybridization (FISH) was used to determine...... exclusively to strict aceticlastic methanogens. Results obtained in this study, demonstrated for the first time that strictly aceticlastic methanogens, derived from an enriched culture, can efficiently produce methane under high ammonia levels....

  14. Research on aerodynamic means of isotope enrichment

    International Nuclear Information System (INIS)

    Cattolica, R.J.; Gallagher, R.J.; Talbot, L.; Willis, D.R.; Hurlbut, F.C.; Fiszdon, W.; Anderson, J.B.

    1978-03-01

    The results of a research program directed toward the understanding of the fundamental gas dynamics involved in aerodynamic isotope enrichment are summarized. The specific aerodynamic isotope enrichment method which was examined in this research is based on a velocity slip phenomenon which occurs in the rarefied hypersonic expansion of a heavy molecular weight gas and a light carrier gas in a nozzle or free jet. This particular aerodynamic method was chosen for study because it contains the fundamental molecular physics of other more complex techniques within the context of a one-dimensional flow without boundary effects. From both an experimental and theoretical modeling perspective this provides an excellent basis for testing the experimental and numerical tools with which to investigate more complex aerodynamic isotope enrichment processes. This report consists of three separate parts. Part I contains a theoretical analysis of the velocity slip effect in free jet expansions of binary and ternary gas mixtures. The analysis, based on a source flow model and using moment equations is derived from the Boltzmann equation using the hypersonic approximation. Part II contains the experimental measurements of velocity slip. The numerical simulation of the slip process was carried out by using a Monte-Carlo numerical technique. In addition, comparisons between the theoretical analysis of Part I and the experiments are presented. Part III describes impact pressure measurements of free jet expansions from slot shaped two dimensional nozzles. At least two methods of aerodynamic isotope enrichment (opposed jet and velocity slip) would depend on the use of this type of two dimensional expansion. Flow surveys of single free jet and the interferene of crossed free jets are presented

  15. Automated Information Enrichment for a Better Search

    OpenAIRE

    José Luis Preza

    2016-01-01

    The process of adding the Metadata when uploading a digital object onto a repository is usually manual. This means that the user has to have already at hand the keywords and all the other information about the asset. This paper addresses the possibility of enriching the “manual metadata” by generating automated metadata using the cognitive services provided by technologies like IBM Watson platform. The cognitive computing services offered by IBM Watson automatically generate Semantic Data (in...

  16. Uranium enrichment export control guide: Gaseous diffusion

    Energy Technology Data Exchange (ETDEWEB)

    1989-09-01

    This document was prepared to serve as a guide for export control officials in their interpretation, understanding, and implementation of export laws that relate to the Zangger International Trigger List for gaseous diffusion uranium enrichment process components, equipment, and materials. Particular emphasis is focused on items that are especially designed or prepared since export controls are required for these by States that are party to the International Nuclear Nonproliferation Treaty.

  17. Experience with a fuel rod enrichment scanner

    International Nuclear Information System (INIS)

    Kubik, R.N.; Pettus, W.G.

    1975-01-01

    This enrichment scanner views all fuel rods produced at B and W's Commercial Nuclear Fuel Plant. The scanner design is derived from the PAPAS System reported by R. A. Forster, H. D. Menlove, and their associates at Los Alamos. The spatial resolution of the system and smoothing of the data are discussed in detail. The cost-effectiveness of multi-detector versus single detector scanners of this general design is also discussed

  18. 21 CFR 137.305 - Enriched farina.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Enriched farina. 137.305 Section 137.305 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... riboflavin, not less than 16.0 mg and not more than 20.0 mg of niacin or niacinamide, not less than 0.7 mg...

  19. Method for separation and enrichment of isotopes

    International Nuclear Information System (INIS)

    Kakihana, H.; Miyamatsu, T.

    1977-01-01

    Boron or uranium isotopes can be chemically separated and enriched with high speed and with high separating efficiency by using weakly basic anion exchange fibers having a diameter of not more than 100 μ, an aspect ratio of at least 5 and an exchange capacity of at least 2 meq/g-dry fiber, which are packed in a column at a specific volume of 2.0 to 20.0 ml/g-dry fiber

  20. Supply of enriched uranium for research reactors

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, H. [NUKEM GmbH, Alzenau (Germany)

    1997-08-01

    Since the RERTR-meeting In Newport/USA in 1990 the author delivered a series of papers in connection with the fuel cycle for research reactors dealing with its front-end. In these papers the author underlined the need for unified specifications for enriched uranium metal suitable for the production of fuel elements and made proposals with regard to the re-use of in Europe reprocessed highly enriched uranium. With regard to the fuel cycle of research reactors the research reactor community was since 1989 more concentrating on the problems of its back-end since the USA stopped the acceptance of spent research reactor fuel on December 31, 1988. Now, since it is apparent that these back-end problem have been solved by AEA`s ability to reprocess and the preparedness of the USA to again accept physically spent research reactor fuel the author is focusing with this paper again on the front-end of the fuel cycle on the question whether there is at all a safe supply of low and high enriched uranium for research reactors in the future.

  1. Integrated design of SIGMA uranium enrichment plants

    International Nuclear Information System (INIS)

    Rivarola, Martin E.; Brasnarof, Daniel O.

    1999-01-01

    In the present work, we describe a preliminary analysis of the design feedbacks in a Uranium Enrichment Plant, using the SIGMA concept. Starting from the result of this analysis, a computer code has been generated, which allows finding the optimal configurations of plants, for a fixed production rate. The computer code developed includes the model of the Thermohydraulic loop of a SIGMA module. The model contains numerical calculations of the main components of the circuit. During the calculations, the main components are dimensioned, for a posterior cost compute. The program also makes an estimation of the enrichment gain of the porous membrane, for each separation stage. Once the dimensions of the main components are known, using the enrichment cascade calculation, the capital and operation costs of the plant could be determined. At this point it is simple to calculate a leveled cost of the Separative Work Unit (SWU). A numerical optimizer is also included in the program. This optimizer finds the optimal cascade configuration, for a given set of design parameters. The whole-integrated program permits to investigate in detail the feedback in the component design. Therefore, the sensibility of the more relevant parameters can be computed, with respect of the economical variables of the plant. (author)

  2. Tellurium Enrichment in Jurassic Coal, Brora, Scotland

    Directory of Open Access Journals (Sweden)

    Liam Bullock

    2017-11-01

    Full Text Available Mid-Jurassic pyritic coals exposed at the village of Brora, northern Scotland, UK, contain a marked enrichment of tellurium (Te relative to crustal mean, average world coal compositions and British Isles Carboniferous coals. The Te content of Brora coal pyrite is more than one order of magnitude higher than in sampled pyrite of Carboniferous coals. The Te enrichment coincides with selenium (Se and mercury (Hg enrichment in the rims of pyrite, and Se/Te is much lower than in pyrites of Carboniferous coals. Initial pyrite formation is attributed to early burial (syn-diagenesis, with incorporation of Te, Se, Hg and lead (Pb during later pyrite formation. The source of Te may have been a local hydrothermal system which was responsible for alluvial gold (Au in the region, with some Au in Brora headwaters occurring as tellurides. Anomalous Te is not ubiquitous in coal, but may occur locally, and is detectable by laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS.

  3. Criticality analysis in uranium enrichment plant

    International Nuclear Information System (INIS)

    Okamoto, Tsuyoshi; Kiyose, Ryohei

    1977-01-01

    In a large scale uranium enrichment plant, uranium inventory in cascade rooms is not very large in quantity, but the facilities dealing with the largest quantity of uranium in that process are the UF 6 gas supply system and the blending system for controlling the product concentration. When UF 6 spills out of these systems, the enriched uranium is accumulated, and the danger of criticality accident is feared. If a NaF trap is placed at the forestage of waste gas treatment system, plenty of UF 6 and HF are adsorbed together in the NaF trap. Thus, here is the necessity of checking the safety against criticality. Various assumptions were made to perform the computation surveying the criticality of the system composed of UF 6 and HF adsorbed on NaF traps with WIMS code (transport analysis). The minimum critical radius resulted in about 53 cm in case of 3.5% enriched fuel for light water reactors. The optimum volume ratio of fissile material in the double salt UF 6 .2NaF and NaF.HF is about 40 vol. %. While, criticality survey computation was also made for the annular NaF trap having the central cooling tube, and it was found that the effect of cooling tube radius did not decrease the multiplication factor up to the cooling tube radius of about 5 cm. (Wakatsuki, Y.)

  4. Update on international uranium and enrichment supply

    International Nuclear Information System (INIS)

    Cleveland, J.M.

    1987-01-01

    Commercial nuclear power generation came upon us in the late 1950s and should have been relatively uneventful due to its similarities to fossil-powered electrical generation. Procurement of nuclear fuel appears to have been treated totally different from the procurement of fossil fuel, however, and only recently have these practices started to change. The degree of utility reliance on US-mined uranium and US Dept. of Energy (DOE)-produced enrichment services has changed since the 1970s as federal government uncertainty, international fuel market opportunity, and public service commission scrutiny has increased. Accordingly, the uranium and enrichment market has recognized that it is international just like the fossil fuel market. There is now oversupply-driven competition in the international nuclear fuel market. Competition is increasing daily, as third-world countries develop their own nuclear resources. American utilities are now diversifying their fuel supply arrangements, as they do with their oil, coal, and gas supply. The degree of foreign fuel arrangements depends on each utility's risk posture and commitment to long-term contracts. In an era of rising capital, retrofit, operating, and maintenance costs, economical nuclear fuel supply is even more important. This economic advantage, however, may be nullified by congressional and judicial actions limiting uranium importation and access to foreign enrichment. Such artificial trade barriers will only defeat US nuclear generation and the US nuclear fuel industry in the long term

  5. DOE and the United States enrichment market

    International Nuclear Information System (INIS)

    Rutkowski, E.E.

    1993-01-01

    The US Department of Energy (DOE) and its predecessors have exerted a predominant influence in the uranium enrichment services industry since 1969, when it began to sell its services to private industry under a Requirement-Type Contract (RTC). After almost 25 years of providing these services to utilities throughout the world, DOE is now preparing to hand over responsibility to the emerging US Enrichment Corporation (USEC), which was created by the 1992 Energy Bill and will begin its tenure on July 1, 1993. DOE has had some notable successes, including revenue generation of about $25 billion from its domestic and foreign sales since 1969. Annual revenues from civilian dollars over the next several years. However, most of the sales attributed to these revenues took place in 1986-more than six years ago. Presently, US utility commitments are decreasing significantly; to date, US utilities have committed less than two percent of their total FY2002 enrichment requirements to DOE. In spite of the fact that DOE has enjoyed some success, its past actions, or sometimes inactions, have often been steeped in controversy that resulted in customer alienation and dissatisfaction. It is the legacy of past DOE contracting practices, increased competition, and massive contractual terminations, that USEC will inherit from DOE. Therefore, it is relevant to consider the major issues that have fashioned the current US market and resulted in USEC's initial position in the marketplace

  6. URENCO. Uranium enrichment with advanced technology

    International Nuclear Information System (INIS)

    2011-01-01

    URENCO Deutschland is a subsidiary of URENCO Enrichment Company Limited, an international enterprise founded in 1970 in the State Treaty of Almelo, which offers uranium enrichment for nuclear power plants all over the world with the use of advanced technology. URENCO facilities at present are operated in the United Kingdom, the Netherlands, USA, and in Germany. The German URENCO location is Gronau, Westphalia, where cascades have been in operation since 1985 using centrifuge technology to enrich nuclear fuel to up to 5% uranium-235. The URENCO Group supplies nuclear power plants in Europe and overseas countries with a world market share, at present, of more than 25% with a rising tendency. The first uranium separation plant in Gronau (UTA-1) attained its full separation performance of 1,800 t USW/a in late 2005. In February 2005, construction and operation of another plant had been licensed, which can raise the aggregate capacity on site to 4,500 t USW per annum. Construction of the new plant (UTA-2) was begun in summer 2005. UTA-2 will use the latest, most powerful URENCO centrifuge. URENCO has more than 3,500 visitors a year at its German location alone, thus demonstrating its pro-active information policy and offering to the public a maximum of opportunities to acquire information by attending presentations and tours of the plant. (orig.)

  7. Technical status study of heavy water enrichment

    International Nuclear Information System (INIS)

    Sukarsono; Imam Dahroni; Didik Herhady

    2007-01-01

    Technical status study of heavy water enrichment in Indonesia and also in the world has been done. Heavy water enrichment processes have been investigated were water distillation, hydrogen distillation, laser enrichment, electrolysis and isotop exchange. For the isotop exchange, the chemical pair can be used were water-hydrogen sulphite, ammonium-hydrogen, aminomethane-hydrogen, and water-hydrogen. For the isotope exchange, there was carried out by mono thermal or bi thermal. The highest producer of heavy water is Canada, and the other producer is USA, Norwegian and India. The processes be used in the world are isotope exchange Girdler Sulphide (GS), distillation and electrolysis. Research of heavy water carried out in Batan Yogyakarta, has a purpose to know the characteristic of heavy water purification. Several apparatus which has erected were 3 distillation column: Pyrex glass of 2 m tall, stainless steel column of 3 m tall and steel of 6 m tall. Electrolysis apparatus is 50 cell electrolysis and an isotope exchange unit which has catalyst: Ni- Cr 2 O 3 and Pt-Carbon. These apparatus were not ready to operate. (author)

  8. Supply of enriched uranium for research reactors

    International Nuclear Information System (INIS)

    Mueller, H.

    1997-01-01

    Since the RERTR-meeting In Newport/USA in 1990 the author delivered a series of papers in connection with the fuel cycle for research reactors dealing with its front-end. In these papers the author underlined the need for unified specifications for enriched uranium metal suitable for the production of fuel elements and made proposals with regard to the re-use of in Europe reprocessed highly enriched uranium. With regard to the fuel cycle of research reactors the research reactor community was since 1989 more concentrating on the problems of its back-end since the USA stopped the acceptance of spent research reactor fuel on December 31, 1988. Now, since it is apparent that these back-end problem have been solved by AEA's ability to reprocess and the preparedness of the USA to again accept physically spent research reactor fuel the author is focusing with this paper again on the front-end of the fuel cycle on the question whether there is at all a safe supply of low and high enriched uranium for research reactors in the future

  9. Comments on Smith Barney's uranium enrichment analysis

    International Nuclear Information System (INIS)

    Rezendes, V.S.

    1990-07-01

    In a May 1990 report, Smith Barney, Harris Upham and Co. concluded that DOE's uranium enrichment program should be restructured as a government corporation; all past costs have been recovered, and DOE's customers have been overcharged about $1.2 billion; the government should retain responsibility for environment and decommissioning costs associated with enriched uranium production before the corporation's formation; and at some future time the corporation could be sold to the private sector. This report agrees with Smith Barney's recommendation to restructure the enrichment program as a government corporation, but disagrees that DOE's customers have paid for all past costs. According to the author, Smith Barney did not identify the total environmental or decommissioning costs between the government and the corporation. Since these costs are largely undefined, but could amount to billions, Congress should immediately require the program to begin setting aside funds for these costs. DOE estimates that government purchases are responsible for 50 percent of the decommissioning costs; therefore, the government should share these costs by matching the corporation's fund contributions. This requirement should continue until the existing plants have been decommissioned

  10. R and D on laser uranium enrichment

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    An AEC Advisory Committee on Uranium Enrichment has completed investigations into the actual condition of laser isotope separation. The working group set up for the purpose has issued a report on the series of investigations made on its development and measures for promoting it. The report says that the development of the process in Japan is at a fundamental stage. Noting that further efforts are needed before its future can be predicted, the report proposes a cource of research and development for the immediate future. For the atomic vapor laser isotope separation (AVLIS), government organizations are engaged in data base buildup and conducting basis engineering tests, and Japan Atomic Energy Research Institute will consider the re-enrichment of uranium recovered from reprocessing. Non-governmental unions of researchers will promote the combination of copper-vapor laser and dye laser. For the molecular laser isotope separation (MLIS), the Institute of Physical and Chemical Research will take up studies with the cooperation of the Power Reactor and Nuclear Fuel Development Corporation. In chapters covering the philosophy of laser uranium enrichment technology development, the report deals with its significance, actual conditions and tasks, and goals and measures for its promotion. (Nogami, K.)

  11. NAA analysis of enriched Zn-68 by

    International Nuclear Information System (INIS)

    Rafii, H.; Mirzaei, M.; Mirzajani, N.; Sardari, D.; Shahabi, I.; Majedi, F.

    2002-01-01

    Excessive application of enriched isotopes in various fields of sciences and industry necessitates measuring their abundant by a precise and rapid methos. Beside the inductively coupled plasma mass spectrometry, the thermal neutron activation analysis, NAA, is an alternative method, which is capable to determine trace amounts of elements as well as the elemental abundance. In this article the enrichment of Zn-68 in two different samples has been studied by mean of NAA. One sample was separated by an electromagnetic system in our center and the other was purchased from a French company, Cortecnet. The neutron irradiation was took place in MNSR reactor by flux 10 1 1n/cm 2 sec. for 30 min. and the produced radioactivity from Zn-69 m was measured one day after irradiation by HPGe detector. The results shows a good agreement with the reported ones and its low derivation of about ±3.05 indicates that the NAA is a precise, rapid, and supplemental method for analyzing enriched Zn-68

  12. The effects of auditory enrichment on gorillas.

    Science.gov (United States)

    Robbins, Lindsey; Margulis, Susan W

    2014-01-01

    Several studies have demonstrated that auditory enrichment can reduce stereotypic behaviors in captive animals. The purpose of this study was to determine the relative effectiveness of three different types of auditory enrichment-naturalistic sounds, classical music, and rock music-in reducing stereotypic behavior displayed by Western lowland gorillas (Gorilla gorilla gorilla). Three gorillas (one adult male, two adult females) were observed at the Buffalo Zoo for a total of 24 hr per music trial. A control observation period, during which no sounds were presented, was also included. Each music trial consisted of a total of three weeks with a 1-week control period in between each music type. The results reveal a decrease in stereotypic behaviors from the control period to naturalistic sounds. The naturalistic sounds also affected patterns of several other behaviors including locomotion. In contrast, stereotypy increased in the presence of classical and rock music. These results suggest that auditory enrichment, which is not commonly used in zoos in a systematic way, can be easily utilized by keepers to help decrease stereotypic behavior, but the nature of the stimulus, as well as the differential responses of individual animals, need to be considered. © 2014 Wiley Periodicals, Inc.

  13. The supply of the European community countries with enriched uranium

    International Nuclear Information System (INIS)

    1975-02-01

    A discussion is given of a survey regarding the supply of enriched uranium to the countries of the European Community. Costs of enriched uranium imports were not available but import values were calculated using world market prices. (R.L.)

  14. Civilian inventories of plutonium and highly enriched uranium

    International Nuclear Information System (INIS)

    Albright, D.

    1987-01-01

    In the future, commercial laser isotope enrichment technologies, currently under development, could make it easier for national to produce highly enriched uranium secretly. The head of a US firm that is developing a laser enrichment process predicts that in twenty years, major utilities and small countries will have relatively small, on-site, laser-based uranium enrichment facilities. Although these plants will be designed for the production of low enriched uranium, they could be modified to produce highly enriched uranium, an option that raises the possibility of countries producing highly enriched uranium in small, easily hidden facilities. Against this background, most of this report describes the current and future quantities of plutonium and highly enriched uranium in the world, their forms, the facilities in which they are produced, stored, and used, and the extent to which they are transported. 5 figures, 10 tables

  15. Fast Enrichment Screening for Safeguards Applications

    International Nuclear Information System (INIS)

    Simpson, A.; McElhaney, S.

    2010-01-01

    Methods for rapid non-destructive uranium enrichment classification of large containers are of importance to safeguards and counter-terrorism agencies. There is a need to quickly categorize and segregate suspect items as 'depleted' or 'enriched' on a 'Go/No Go' basis. Recent improvements in gamma spectroscopy technologies have provided the capability to perform rapid field analysis using portable and hand-held devices such as battery-operated medium and high resolution detectors (including lanthanum halide and high purity germanium). Furthermore a new generation of portal monitors are currently under development with advanced spectroscopic capabilities. Instruments and technologies that were previously the domain of complex lab systems are now widely available as touch-screen 'off-the-shelf' units. Despite such advances, the task of enrichment analysis remains a complex exercise. This is particularly so when surveying large items such as drums and crates containing debris of unknown density and composition contaminated with uranium. The challenge is equally applicable to safeguards inspectors evaluating large items and for interdiction of illicit special nuclear materials in mass transport e.g. shipping containers at ports and borders. The variable shielding, container size, lack of matrix knowledge, wall thickness and self-shielding compound this problem. Performing an accurate assessment within the short count time window demanded of the field operative, leads to the need for a reliable method that can adapt to such conditions and is robust to a wide dynamic range of counting statistics. Several methods are evaluated with reference to the performance metrics defined in applicable standards. The primary issue is to minimize the bias that can result from attenuation effects, particularly as the gamma emissions from U235 are low energy and therefore highly susceptible to absorption in large containers with metal scrap. Use of other radiometric signatures such as

  16. A Resolution of the Paradox of Enrichment

    Science.gov (United States)

    Feng, Z. C.; Li, Y. Charles

    2015-06-01

    The paradox of enrichment was observed by Rosenzweig [1971] in a class of predator-prey models. Two of the parameters in the models are crucial for the paradox. These two parameters are the prey's carrying capacity and prey's half-saturation for predation. Intuitively, increasing the carrying capacity due to enrichment of the prey's environment should lead to a more stable predator-prey system. Analytically, it turns out that increasing the carrying capacity always leads to an unstable predator-prey system that is susceptible to extinction from environmental random perturbations. This is the so-called paradox of enrichment. Our resolution here rests upon a closer investigation on a dimensionless number H formed from the carrying capacity and the prey's half-saturation. By recasting the models into dimensionless forms, the models are in fact governed by a few dimensionless numbers including H. The effects of the two parameters: carrying capacity and half-saturation are incorporated into the number H. In fact, increasing the carrying capacity is equivalent (i.e. has the same effect on H) to decreasing the half-saturation which implies more aggressive predation. Since there is no paradox between more aggressive predation and instability of the predator-prey system, the paradox of enrichment is resolved. The so-called instability of the predator-prey system is characterized by the existence of a stable limit cycle in the phase plane, which gets closer and closer to the predator axis and prey axis. Due to random environmental perturbations, this can lead to extinction. We also further explore spatially dependent models for which the phase space is infinite-dimensional. The spatially independent limit cycle which is generated by a Hopf bifurcation from an unstable steady state, is linearly stable in the infinite-dimensional phase space. Numerical simulations indicate that the basin of attraction of the limit cycle is riddled. This shows that spatial perturbations can

  17. Competing for the non-US enrichment markets

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    The article discusses three basic steps: first, the historical perspectives; second, where the enrichment industry and the non-US markets for enrichment stand today (the present situation); and third, the likely future developments, which, for practical purposes, are dealt with in two parts: the non-US enrichment markets in the 1980s; and the non-US enrichment markets beyond the 1980s;

  18. Method and apparatus for enrichment or upgrading heavy water

    International Nuclear Information System (INIS)

    Butler, J.P.; Hammerli, M.

    1979-01-01

    A method and apparatus for upgrading and final enrichment of heavy water are described, comprising means for contacting partially enriched heavy water feed in a catalyst column with hydrogen gas (essentially D 2 ) originating in an electrolysis cell so as to enrich the feed water with deuterium extracted from the electrolytic hydrogen gas and means for passing the deuterium enriched water to the electrolysis cell. (author)

  19. 31 CFR 540.306 - Highly Enriched Uranium (HEU).

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 3 2010-07-01 2010-07-01 false Highly Enriched Uranium (HEU). 540...) OFFICE OF FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY HIGHLY ENRICHED URANIUM (HEU) AGREEMENT ASSETS CONTROL REGULATIONS General Definitions § 540.306 Highly Enriched Uranium (HEU). The term highly...

  20. A theory of surface enrichment in ordered alloys

    NARCIS (Netherlands)

    Santen, van R.A.; Sachtler, W.M.H.

    1974-01-01

    A simple theory was developed to explain exptl. data on surface enrichment in Pt3Sn. The computed surface enrichment is in accord with exptl. findings. The theory predicts that in the Pt3Sn system enrichment occurs by interchange of atoms of the element with the lower heat of sublimation from the

  1. Enrichment of sub-milligram size carbon samples

    NARCIS (Netherlands)

    Kitagawa, H; vanderPlicht, J

    We have developed a carbon isotope enrichment system for use in conjunction with the Groningen Accelerator Mass Spectrometer. Using thermal diffusion of CO, we obtained an enrichment factor of about 3 for C-13 for half-gram carbon in 5 days. This means we expect for C-14 an enrichment factor of 6,

  2. 75 FR 21680 - GE-Hitachi Global Laser Enrichment LLC;

    Science.gov (United States)

    2010-04-26

    ... Global Laser Enrichment LLC; Establishment of Atomic Safety and Licensing Board Pursuant to delegation by... over the following proceeding: GE-Hitachi Global Laser Enrichment LLC (GLE Commercial Facility) This... application of GE-Hitachi Global Laser Enrichment LLC for a license to possess and use source, byproduct, and...

  3. Long term assurance of supply of uranium enrichment

    International Nuclear Information System (INIS)

    1978-01-01

    After elaborating a number of key questions on uranium enrichment, the representatives of 10 countries and of the EC commission present their answers. Attention is paid to the assurance of uranium supply, to uranium enrichment, market trends and flexibility in enrichment agreements

  4. Supply of low enriched (LEU) and highly enriched uranium (HEU) for research reactors

    International Nuclear Information System (INIS)

    Mueller, H.

    1997-01-01

    Enriched uranium for research reactors in the form of LEU /= low enriched uranium at 19.75% U-235) and HEU (= highly enriched uranium at 90 to 93% U-235) was and is - due to its high U-235 enrichment - a political fuel other than enriched uranium for power reactors. The sufficient availability of LEU and HEU is a vital question for research reactors, especially in Europe, in order to perform their peaceful research reactor programs. In the past the USA were in the Western hemisphere sole supplier of LEU and HEU. Today the USA have de facto stopped the supply of LEU and HEU, for HEU mainly due to political reasons. This paper deals, among others, with the present availability of LEU and HEU for European research reactors and touches the following topics: - historical US supplies, - influence of the RERTR-program, - characteristics of LEU and HEU, - military HEU enters the civil market, -what is the supply situation for LEU and HEU today? - outlook for safe supplies of LEU and HEU. (author)

  5. 77 FR 13367 - General Electric-Hitachi Global Laser Enrichment, LLC, Proposed Laser-Based Uranium Enrichment...

    Science.gov (United States)

    2012-03-06

    ... NUCLEAR REGULATORY COMMISSION [NRC-2009-0157] General Electric-Hitachi Global Laser Enrichment, LLC, Proposed Laser-Based Uranium Enrichment Facility, Wilmington, NC AGENCY: Nuclear Regulatory... Impact Statement (EIS) for the proposed General Electric- Hitachi Global Laser Enrichment, LLC (GLE...

  6. Measurement of the enrichment of uranium in the pipework of a gas centrifuge enrichment plant

    International Nuclear Information System (INIS)

    Packer, T.W.; Lees, E.W.; Close, D.; Nixon, K.V.; Pratt, J.C.; Strittmatter, R.

    1985-01-01

    The US and UK have been separately working on the development of a NDA instrument to determine the enrichment of gaseous UF 6 at low pressures in cascade header pipework in line with the conclusions of the Hexapartite Safeguards Project viz. the instrument is capable of making a ''go/no go'' decision of whether the enrichment is less than/greater than 20%. Recently, there has been a series of very useful technical exchanges of ideas and information between the two countries. This has led to a technical formulation for such an instrumentation based on γ-ray spectrometry which, although plant-specific in certain features, nevertheless is based on the same physical principles. Experimental results from commercially operating enrichment plants are very encouraging and indicate that a complete measurement including set up time on the pipe should be attainable in about 30 minutes when measuring pipes of diameter around 110 mm. 5 refs., 4 figs

  7. Safeguards for reprocessing and enrichment plants

    International Nuclear Information System (INIS)

    1977-01-01

    Agency safeguards are entering a new phase with the coming under active safeguards for the first time of reprocessing plants in several regions of the world. This is taking place at a time when not only the safeguards aspect itself is coming under international scrutiny, but also at a time when the necessity of reprocessing plants is being called into question. Attracting less attention at the moment, but potentially of equal significance, are the enrichment plants that soon will be coming under Agency safeguards. It is not unreasonable in view of the present controversies to ask what is the significance of these reprocessing and enrichment plants, what are the problems concerning safeguards that appear to have given rise to the controversies, and how these problems are to be solved. The question of significance is an easy one to answer. The output of these plants is material which some people consider can be used directly for military purposes, whereas the output from other plants, for instance, reactors, would require long and extensive processing before it could be used for military purposes. Like most short answers, this one is an over-simplification which requires some elaboration to make it strictly accurate. For example, the material output of a power reactor is in the form of irradiate assemblies containing plutonium which is potentially of military use if the irradiation had been within a certain range. However, to utilize this plutonium under clandestine conditions, the highly radioactive material would have to be secretly transported to a reprocessing plant and there would have to be simultaneous falsification of the reactor material accounts and the plant records. Such falsification would be difficult to conceal. The total time required to obtain usable plutonium would be many months. Diversion of material from a uranium fabrication plant making fuel for power reactors would be easier physically but strategically it would be of little value. The

  8. Optimal set of selected uranium enrichments that minimizes blending consequences

    International Nuclear Information System (INIS)

    Nachlas, J.A.; Kurstedt, H.A. Jr.; Lobber, J.S. Jr.

    1977-01-01

    Identities, quantities, and costs associated with producing a set of selected enrichments and blending them to provide fuel for existing reactors are investigated using an optimization model constructed with appropriate constraints. Selected enrichments are required for either nuclear reactor fuel standardization or potential uranium enrichment alternatives such as the gas centrifuge. Using a mixed-integer linear program, the model minimizes present worth costs for a 39-product-enrichment reference case. For four ingredients, the marginal blending cost is only 0.18% of the total direct production cost. Natural uranium is not an optimal blending ingredient. Optimal values reappear in most sets of ingredient enrichments

  9. Modeling Profiles and Signatures of Enrichments

    Science.gov (United States)

    Ali, A.; Qualls, C.; Lucas, S. G.; Lombari, G.; Appenzeller, O.

    2014-12-01

    Anthropogenic and geochemical enrichment of soils and living matter have been well documented 1, 2, 3.Here we report on geochemical, anthropogenic and biological enrichments with heavy metals in Modern Peru and compared this to Modern and ancient data from New Mexico, USA. We established a signature derived from the quantities of 25 metals in various biological, fossil and soil materials. We also speculate that human adaptation to mercury toxicity may occur in remarkably short time spans during the Holocene. We found mercury concentrations in Modern pigeon feathers and llama wool from free foraging birds and animals in Albuquerque, NM, ranging from 0.006 to 0.019 mg/Kg of tissue. The values for Modern Peru ranged from 22.0 to 556 mg/Kg for the same tissues. We discovered, in 64 million-year-old fossilized plants from New Mexico (Paleocene Nacimiento Formation, San Juan Basin), a mercury concentration of 1.11 mg/Kg of fossil, whereas Modern plant material from the Rio Grande Basin in New Mexico contained no mercury. Profiling of metal content of these samples suggests that mercury is a proxy for anthropogenic rather than geochemical enrichment in the localities we examined. We found no overt signs of mercury toxicity in contemporaneous inhabitants of Huancavelica4, Peru; one of the ten most mercury-polluted places in the world and the mercury concentration in their hair is well below modern admissible levels. However, assessment of their annual scalp hair growth-rate showed marked reduction in growth (~ 5cm/yr) versus ~ 16cm/year for normal scalp hair from other continents4. This is consistent with a toxic effect of heavy metals on human metabolism and especially autonomic nervous system function in Huancavelica, Peru. Contemporaneous anthropogenic activities are known to increase heavy metal content in the biosphere with potentially toxic effects on humans. However, signs of human evolutionary adaptation to such toxins might already be evident in Peru4.

  10. Nitrogen enrichment regulates calcium sources in forests

    Science.gov (United States)

    Hynicka, Justin D.; Pett-Ridge, Julie C.; Perakis, Steven

    2016-01-01

    Nitrogen (N) is a key nutrient that shapes cycles of other essential elements in forests, including calcium (Ca). When N availability exceeds ecosystem demands, excess N can stimulate Ca leaching and deplete Ca from soils. Over the long term, these processes may alter the proportion of available Ca that is derived from atmospheric deposition vs. bedrock weathering, which has fundamental consequences for ecosystem properties and nutrient supply. We evaluated how landscape variation in soil N, reflecting long-term legacies of biological N fixation, influenced plant and soil Ca availability and ecosystem Ca sources across 22 temperate forests in Oregon. We also examined interactions between soil N and bedrock Ca using soil N gradients on contrasting basaltic vs. sedimentary bedrock that differed 17-fold in underlying Ca content. We found that low-N forests on Ca-rich basaltic bedrock relied strongly on Ca from weathering, but that soil N enrichment depleted readily weatherable mineral Ca and shifted forest reliance toward atmospheric Ca. Forests on Ca-poor sedimentary bedrock relied more consistently on atmospheric Ca across all levels of soil N enrichment. The broad importance of atmospheric Ca was unexpected given active regional uplift and erosion that are thought to rejuvenate weathering supply of soil minerals. Despite different Ca sources to forests on basaltic vs. sedimentary bedrock, we observed consistent declines in plant and soil Ca availability with increasing N, regardless of the Ca content of underlying bedrock. Thus, traditional measures of Ca availability in foliage and soil exchangeable pools may poorly reflect long-term Ca sources that sustain soil fertility. We conclude that long-term soil N enrichment can deplete available Ca and cause forests to rely increasingly on Ca from atmospheric deposition, which may limit ecosystem Ca supply in an increasingly N-rich world.

  11. Cheese bread enriched with biofortified cowpea flour

    Directory of Open Access Journals (Sweden)

    Rodrigo Barbosa Monteiro Cavalcante

    2016-02-01

    Full Text Available ABSTRACT The development and enrichment of food are of great importance not only for the industry but also to improve the population's nutrition, where you can create new products or optimize existing ones. The consumption of fortified products in the diet is an option for the control of deficiency diseases. This study aimed to develop enriched cheese bread with whole biofortified cowpea flour and evaluate their acceptance and chemical composition. Two formulations, F1 and F2, were prepared containing 5.6 and 8% of cowpea flour as a substitute for starch, respectively. To check acceptance, three sensory tests were used (Hedonic Scale, Purchase Intent, and Paired Comparison, F1 being sensory viable according to assessors, being chemically analyzed. Minerals were determined by atomic emission spectrometry with inductively coupled plasma source. The moisture was determined by drying at 105 °C, ash by calcination in muffle at 550 °C, proteins by the macro-Kjeldahl method, and lipids by hot extraction in a Soxhlet extractor. Carbohydrates were obtained by difference and the calories were calculated. The addition of cowpea increased the amounts of copper, iron, phosphorus, magnesium, manganese, and zinc, as well as protein and carbohydrate values. On the other hand, there was a reduction of the moisture concerning lipids and the total caloric value compared to the standard formulation. It was concluded , therefore, that the cowpea, a regional raw material in market expansion is presented as an option for the enrichment of baked foods that do not contain gluten, such as cheese bread.

  12. History of enrichment research at the CEA

    International Nuclear Information System (INIS)

    Camarcat, N.

    1996-01-01

    French researches about uranium enrichment have been carried out at the CEA for about 40 years. In the beginning, these researches were considered as marginal and were carried out by a small team from the Powders Central Laboratory. They became intensive since 1955 and culminated in 1967 with the conception of Pierrelatte's factory. Several processes were studied: the gaseous diffusion, the chemical treatments, the centrifugation, the laser and electromagnetic separation processes on atomic and molecular vapors. Only a few of them were fully developed. This paper summarizes the development of these different processes in their historical context. (J.S.). 1 fig

  13. France makes steady progress with lasers [enrichment

    International Nuclear Information System (INIS)

    Coates, J.-H.; Clerc, M.; Plurien, P.

    1988-01-01

    With the CHEMEX process now a commercially available technology, the French Commissariat a l'Energie (CEA) is focussing its R and D activity on two enrichment processes: gaseous diffusion, and atomic vapour laser isotope separation (AVLIS or SILVA). The SILVA process is being developed, with particular attention being paid to test campaigns undertaken on the pilot unit installed at Saclay. A core of technical know-how is being maintained in gaseous diffusion in order to study the behaviour of, and possible improvements to, the newly named George Besse plant at the Tricastin site. (U.K.)

  14. Legal and regulatory framework of Uranium's enrichment

    International Nuclear Information System (INIS)

    Antelo, Josefina; Figueredo, Micaela S.; Mangone, Gisela P.; Manin, Maria L.; Pota, Luciana F.

    2009-01-01

    The object of this paper is to develop the legal aspects referred to the activities of uranium's enrichment, in order to achieve the pacific use of nuclear energy and to obey treatments, agreements and international conventions in which Argentine is party and through them assumes the non proliferation's commitment. In this context, we will develop the rights and obligations established in those legal instruments, as well as the juridical concerns of the eventual subscription of Argentine to the Additional Protocol approved by the Board of Governors in 1997. (author)

  15. Surplus Highly Enriched Uranium Disposition Program plan

    International Nuclear Information System (INIS)

    1996-10-01

    The purpose of this document is to provide upper level guidance for the program that will downblend surplus highly enriched uranium for use as commercial nuclear reactor fuel or low-level radioactive waste. The intent of this document is to outline the overall mission and program objectives. The document is also intended to provide a general basis for integration of disposition efforts among all applicable sites. This plan provides background information, establishes the scope of disposition activities, provides an approach to the mission and objectives, identifies programmatic assumptions, defines major roles, provides summary level schedules and milestones, and addresses budget requirements

  16. Active interrogation of highly enriched uranium

    Science.gov (United States)

    Fairrow, Nannette Lea

    Safeguarding special nuclear material (SNM) in the Department of Energy Complex is vital to the national security of the United States. Active and passive nondestructive assays are used to confirm the presence of SNM in various configurations ranging from waste to nuclear weapons. Confirmation measurements for nuclear weapons are more challenging because the design complicates the detection of a distinct signal for highly enriched uranium. The emphasis of this dissertation was to investigate a new nondestructive assay technique that provides an independent and distinct signal to confirm the presence of highly enriched uranium (HEU). Once completed and tested this assay method could be applied to confirmation measurements of nuclear weapons. The new system uses a 14-MeV neutron source for interrogation and records the arrival time of neutrons between the pulses with a high efficiency detection system. The data is then analyzed by the Feynman reduced variance method. The analysis determined the amount of correlation in the data and provided a unique signature of correlated fission neutrons. Measurements of HEU spheres were conducted at Los Alamos with the new system. Then, Monte Carlo calculations were performed to verify hypothesis made about the behavior of the neutrons in the experiment. Comparisons of calculated counting rates by the Monte Carlo N-Particle Transport Code (MCNP) were made with the experimental data to confirm that the measured response reflected the desired behavior of neutron interactions in the highly enriched uranium. In addition, MCNP calculations of the delayed neutron build-up were compared with the measured data. Based on the results obtained from this dissertation, this measurement method has the potential to be expanded to include mass determinations of highly enriched uranium. Although many safeguards techniques exist for measuring special nuclear material, the number of assays that can be used to confirm HEU in shielded systems is

  17. Monitoring the enrichment of the UF6 in the pipework of a gas centrifuge enrichment plant

    International Nuclear Information System (INIS)

    Packer, T.W.; Close, D.A.; Pratt, J.C.

    1987-01-01

    Research in the UK and the US has resulted in the development of a nondestructive assay instrument which can confirm the presence of low enriched uranium, on a rapid Go, No-Go basis, in cascade header pipework in the centrifuge enrichment plant at Capenhurst. The instrument is based on gamma-ray spectrometry and x-ray fluorescence analysis. It allows pipes, 120mm outer diameter, to be inspected in a total measurement time of approximately 30 minutes. This paper describes the techniques developed and includes the results obtained during a demonstration to, and preliminary in-plant measurements by, members of the IAEA and EURATOM Inspectorates at Capenhurst

  18. GOMA: functional enrichment analysis tool based on GO modules

    Institute of Scientific and Technical Information of China (English)

    Qiang Huang; Ling-Yun Wu; Yong Wang; Xiang-Sun Zhang

    2013-01-01

    Analyzing the function of gene sets is a critical step in interpreting the results of high-throughput experiments in systems biology.A variety of enrichment analysis tools have been developed in recent years,but most output a long list of significantly enriched terms that are often redundant,making it difficult to extract the most meaningful functions.In this paper,we present GOMA,a novel enrichment analysis method based on the new concept of enriched functional Gene Ontology (GO) modules.With this method,we systematically revealed functional GO modules,i.e.,groups of functionally similar GO terms,via an optimization model and then ranked them by enrichment scores.Our new method simplifies enrichment analysis results by reducing redundancy,thereby preventing inconsistent enrichment results among functionally similar terms and providing more biologically meaningful results.

  19. Novel Membranes and Processes for Oxygen Enrichment

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Haiqing

    2011-11-15

    The overall goal of this project is to develop a membrane process that produces air containing 25-35% oxygen, at a cost of $25-40/ton of equivalent pure oxygen (EPO2). Oxygen-enriched air at such a low cost will allow existing air-fueled furnaces to be converted economically to oxygen-enriched furnaces, which in turn will improve the economic and energy efficiency of combustion processes significantly, and reduce the cost of CO{sub 2} capture and sequestration from flue gases throughout the U.S. manufacturing industries. During the 12-month Concept Definition project: We identified a series of perfluoropolymers (PFPs) with promising oxygen/nitrogen separation properties, which were successfully made into thin film composite membranes. The membranes showed oxygen permeance as high as 1,200 gpu and oxygen/nitrogen selectivity of 3.0, and the permeance and selectivity were stable over the time period tested (60 days). We successfully scaled up the production of high-flux PFP-based membranes, using MTR's commercial coaters. Two bench-scale spiral-wound modules with countercurrent designs were made and parametric tests were performed to understand the effect of feed flow rate and pressure, permeate pressure and sweep flow rate on the membrane module separation properties. At various operating conditions that modeled potential industrial operating conditions, the module separation properties were similar to the pure-gas separation properties in the membrane stamps. We also identified and synthesized new polymers [including polymers of intrinsic microporosity (PIMs) and polyimides] with higher oxygen/nitrogen selectivity (3.5-5.0) than the PFPs, and made these polymers into thin film composite membranes. However, these membranes were susceptible to severe aging; pure-gas permeance decreased nearly six-fold within two weeks, making them impractical for industrial applications of oxygen enrichment. We tested the effect of oxygen-enriched air on NO{sub x} emissions

  20. Physicochemical properties of cookies enriched with xylooligosaccharides.

    Science.gov (United States)

    Ayyappan, P; Abirami, A; Anbuvahini, N A; Tamil Kumaran, P S; Naresh, M; Malathi, D; Antony, Usha

    2016-07-01

    The growing commercial importance of xylooligosaccharides is based on their beneficial health properties, particularly their ability to stimulate the growth and activity of intestinal bacteria such as Bifidobacterium and Lactobacillus species. Xylooligosaccharides are less sweet, acid, and heat stable, with low recommended levels of intake compared to other oligosaccharides. In view of the consumer demand for foods with low sugar, low fat, and high fiber contents, they are suitable for incorporation into bakery products. In this study, we have developed wheat-based cookies incorporated with xylooligosaccharides at 5%, 10%, and 15% levels. The nutritive value and physicochemical properties of the cookies changed with xylooligosaccharides incorporation; both crude fiber and dietary fiber contents increased by 14% and 35%, respectively, in the enriched cookies. The moisture levels increased with increase in the percentage of xylooligosaccharides incorporated. Cookies with 5% xylooligosaccharides were found most acceptable, although the color was slightly darker compared to the control, while cookies with 10% and 15% xylooligosaccharides were softer and darker and therefore less acceptable. Enrichment with xylooligosaccharides at 5% provided a product stable for 21 days at room temperature (25 ± 2℃). The storage stability of cookies with higher levels of xylooligosaccharides was less than the 5% xylooligosaccharides cookies and control. The retention of the prebiotic xylooligosaccharides in the products was relatively high (74%). © The Author(s) 2015.

  1. Supply of enriched uranium for research reactors

    International Nuclear Information System (INIS)

    Mueller, H.

    2004-01-01

    Since the RERTR-Meeting in Newport/USA in 1990 recommended in several papers to the research reactor community to agree upon a worldwide unified technical specification for low enriched uranium (LEU) and high enriched uranium (HEU) in order to facilitate supplies of LEU and HEU to fabricators for acceptance and for fabrication of fresh fuel elements. This target for unified and simplified specification has only been partially reached due to different interests of the fabricators because they want to receive the uranium as pure as possible. As a result of various investigations, however, it became clear that both LEU and HEU received from the United States since the late fifties had different qualities which we have to deal with today due to the availability of stocks. We are now one step forward to know more precisely the properties of LEU and HEU we have received in the past. This uranium was never virgin and we have to cope with this situation. Therefore in my present paper I have concentrated on the documentation of analytical work performed on samples of LEU and HEU received in the past. I propose furthermore a frame of unified specifications for so-called virgin LEU and HEU including uranium from a Zero-experiment. In addition I am giving a recommendation for specifications of LEU obtained by blending of reprocessed HEU. Finally I am touching the question of secure supplies of fresh LEU. (author)

  2. ENRICHMENT OF POULTRY PRODUCTS WITH FUNCTIONAL INGREDIENTS

    Directory of Open Access Journals (Sweden)

    Gordana Kralik

    2012-06-01

    Full Text Available Primary role of food is to provide nutritive stuffs in sufficient amounts to meet nutritive requirements. However, recent scientific findings confirm assumptions that particular food or its ingredients had positive physiological and psychological effects on health. Functional food is referred to food rich in ingredients, having beneficial effects on one or more functions in an organism. By consuming functional food consumers can expect some health benefits. Production of poultry products as functional food is getting more important on foreign markets while portion of such products on domestic food market is insignificant. The aim of this paper is to present possibilities for enrichment of poultry products, such as broiler and turkey meat and chicken eggs, as they can be characterized as functional food. Functional ingredients in poultry products are polyunsaturated fatty acids (LNA, EPA and DHA and antioxidants. Enrichment of poultry products with the stated ingredients that are beneficial for human health is subject of many researches, and only recently have researches been directed towards assessment of market sustainability of such products.

  3. Analysis of a PHWR slightly enriched fuel

    International Nuclear Information System (INIS)

    Notari, C.; Marajofsky, A.

    1994-01-01

    It is widely known that the use of slightly enriched uranium in PHWR reactors presents economic advantages derived from the fact that less uranium is required for producing the same amount of energy. Several studies related with the use of this alternative in Atucha I NPP have been performed. The fuel assembly geometry considered up to now has been almost identical to the natural uranium one. In this work a modification consisting in the use of annular pellets in the outer ring of the cluster is analyzed. This design produces several performance benefits. The redistribution of the power in the fuel improves the maximum to average bundle power ratio. The improvement achieved depends on the void volume in the pellets which at the same time represents a certain burnup decrease. These parameters (power ratios and burnup loss) are quantified for the Atucha I and Embalse NPPs. This design improves the fuel behaviour with respect to the burnup extension derived from the slight enrichment. It is also interesting in case an overall power increase is considered. (author). 16 refs, 8 figs, 1 tab

  4. Enriching Students’ Vocabulary Mastery Using Graphic Organizers

    Directory of Open Access Journals (Sweden)

    Syaifudin Latif Darmawan

    2017-04-01

    Full Text Available This action research is carried out to (1 identify whether graphic organizers enrich student’s vocabulary mastery; and (2 to describe the classroom situation when graphic organizers are employed in instructional process of vocabulary. The research is conducted in two cycles from March to May 2016/2017 in the eight years of SMP Muhammadiyah Sekampung, East lampung. The procedure of the research consists of identifying the problem, planning the action, implementing the action, observing the action, and reflecting the result of the research. Qualitative data are collected through interview, observation, questionnaire, and research diary. Quantitative data are collected through test. To analyze qualitative data, the researcher used constant comparative method. It consists of four steps: (1 comparing incidents applicable to each category; (2 Integrating categories and their properties; (3 delimiting the theory; (4 Writing the theory. Meanwhile, to analyze quantitative data, the researcher employed descriptive statistic.    The result of the research shows that using graphic organizers can enrich students’ vocabulary mastery and classroom situation. The improvement on students’ vocabulary included; a the students are able to speak English; b the students are able to understand the meaning of the text as they have a lot of vocabularies. The improvement of the classroom situation; (a students come on time in the class (b students are more motivated to join the class (c Students pay more attention in the instructional process (d students’ participation in responding the questions are high.

  5. Nursing satisfaction and job enrichment in Turkey.

    Science.gov (United States)

    Oztürk, Havva; Bahcecik, Nefise; Baumann, Steven L

    2006-10-01

    Survey research was conducted with the aim of better understanding nurses' perceptions of organizational factors which relate to their job satisfaction and motivation in Turkey. Nurses (N = 290) who were employed at a training and research hospital, part of the Turkish Republic Ministry of Health, were included. The questionnaire used was developed for this study based on Hackman and Oldman's job enrichment theory. The results showed that only one third of the nurse leaders and one in five of the staff nurses reported being satisfied with their job. The participants saw the five core job dimensions of Hackman and Oldman's work design model: skill variety, task identity, task significance, autonomy, and feedback as important for nurses. Nursing was described by the participants as hard and challenging, but they also found it meaningful and said that it gave them the opportunity to use their skills and abilities.

  6. Method for the enrichment of isotopes

    International Nuclear Information System (INIS)

    Schuster, E.; Kersting, A.; Gebauhr, W.

    1976-01-01

    A method for the enrichment of isotopes, especially of uranium compounds, is described, working according to the principle of selective excitation by laser beams. As the starting compound, UF 6 is mentioned; the reaction partness are atomic gases (hydrogen, oxygen, nitrogen) or radicals (CH 3 , CHO). According to the invention, the gas mixture flows through the reaction space with a velocity so large that in leaving it, recombination of the reaction partner will already take place again. In this way, competing thermal reactions will be avoided and energy transfer fo excited 235 U molecules to non-excited 238 U molecules is eliminated to a large extent. A suitable equipment for implementing the method is described. (UWI) [de

  7. Glycoprotein Enrichment Analytical Techniques: Advantages and Disadvantages.

    Science.gov (United States)

    Zhu, R; Zacharias, L; Wooding, K M; Peng, W; Mechref, Y

    2017-01-01

    Protein glycosylation is one of the most important posttranslational modifications. Numerous biological functions are related to protein glycosylation. However, analytical challenges remain in the glycoprotein analysis. To overcome the challenges associated with glycoprotein analysis, many analytical techniques were developed in recent years. Enrichment methods were used to improve the sensitivity of detection, while HPLC and mass spectrometry methods were developed to facilitate the separation of glycopeptides/proteins and enhance detection, respectively. Fragmentation techniques applied in modern mass spectrometers allow the structural interpretation of glycopeptides/proteins, while automated software tools started replacing manual processing to improve the reliability and throughput of the analysis. In this chapter, the current methodologies of glycoprotein analysis were discussed. Multiple analytical techniques are compared, and advantages and disadvantages of each technique are highlighted. © 2017 Elsevier Inc. All rights reserved.

  8. Uranium enrichment decontamination and decommissioning fund

    International Nuclear Information System (INIS)

    1994-01-01

    One of the most challenging issues facing the Department of Energy's Office of Environmental Management is the cleanup of the three gaseous diffusion plants. In October 1992, Congress passed the Energy Policy Act of 1992 and established the Uranium Enrichment Decontamination and Decommissioning Fund to accomplish this task. This mission is being undertaken in an environmentally and financially responsible way by: devising cost-effective technical solutions; producing realistic life-cycle cost estimates, based on practical assumptions and thorough analysis; generating coherent long-term plans which are based on risk assessments, land use, and input from stakeholders; and, showing near-term progress in the cleanup of the gaseous diffusion facilities at Oak Ridge

  9. Distribution of uranium supply and enrichment

    International Nuclear Information System (INIS)

    Bamford, F.W.

    1982-01-01

    Uranium supply and demand is examined from the perspective of companies in the uranium hexafluoride (UF6) conversion business whose main interest is their sources of uranium supply and UF6 destinations because of transportation costs. Because of the variations in yellowcake transport, charges for conversion, and UF6 transport costs, most converters don't have standard prices. Companies try to look ahead to determine patterns of supplies and delivery points when they analyze the market and estimate future prices. Market analyses must take into account the purchasing policies of utilities around the world. The presentation shows North America supplying about 40% of world uranium, with about 13% of the enrichment done elsewhere. It also shows North American converters getting 53% of the business, but that will require importing uranium from outside North America. 6 tables

  10. Natural uranium utilization without enrichment and reprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Sekimoto, H.; Toshinsky, V.; Ryu, K. [Tokyo Inst. of Tech. (Japan). Research Lab. for Nuclear Reactors

    2001-07-01

    Two types of fast reactor are investigated to utilize the natural uranium without enrichment and reprocessing in an equilibrium state. The first trial is SFPR. Its fuel-shuffling pattern is optimized. An obtained result gives its peak fuel burnup of 22,5%, power peaking factor of 1.5 and peak excess reactivity of 2,15%. The second trial is CANDLE burnup scheme, where distribution shapes of neutron flux and nuclide densities are constant but move in axial direction with a constant velocity. A feasible solution gives the speed of burning region of 4,1 cm/year, k{sub eff} of 1,02 and average spent fuel burnup of 41%. (author)

  11. Design Enriches Life,Life Breeds Fashion

    Directory of Open Access Journals (Sweden)

    Yun Gong

    2016-11-01

    Full Text Available As society advances and technology changes,fashion design has developed from the initial few exclusive to public demand, and fashion category also covers all walks of life, extends to every area from a single demand to industrialization. Fashion design development, has become an indispensable part of people's lives. Fashion satisfies public demand, reflecting the public interest towards, and designer correctly grasp of fashion and taste of popular motivated the design of continuous innovation to creating new business value, cultural values of the social value of fashion. A precise definition to fashion is hard, cause too broad as it relates to areas, such as products, clothing, entertainment, advertising, decoration, home, fashion is reach into every aspect of our lives. Fashion derived from life elements, convergence elements of era and innovation into your life all over again, this cycle forward and updated, fully embodies the understanding of art and life. Design enriches life, life gave birth to fashion.

  12. Enriching project organizations with formal change agents

    DEFF Research Database (Denmark)

    Eskerod, Pernille; Justesen, Just Bendix; Sjøgaard, Gisela

    2017-01-01

    Purpose: Project success requires effective and efficient cooperation between the project organization and the permanent organization in which the project takes place. The purpose of this paper is to discuss potentials and pitfalls from enriching project organizations by appointing peers as formal...... and middle and top management support are major determinants of success within change projects. To select change agents that the employees respect and can identify with, combined with top management prioritization, is important in order for the project organization to benefit from the additional role...... change agents. Design/methodology/approach: The paper is based on a literature review and a multiple-case study in which six organizations participated in an action-oriented research project. The aim for the organizations was to obtain a better health status among the employees by accomplishing...

  13. Crop responses to CO2 enrichment

    International Nuclear Information System (INIS)

    Rogers, H.H.; Dahlman, R.C.

    1993-01-01

    Carbon dioxide is rising in the global atmosphere, and this increase can be expected to continue into the foreseeable future. This compound is an essential input to plant life. Crop function is affected across all scales from biochemical to agroecosystem. An array of methods (leaf cuvettes, field chambers, free-air release systems) are available for experimental studies of CO 2 effects. Carbon dioxide enrichment of the air in which crops grow usually stimulates their growth and yield. Plant structure and physiology are markedly altered. Interactions between CO 2 and environmental factors that influence plants are known to occur. Implications for crop growth and yield are enormous. Strategies designed to assure future global food security must include a consideration of crop responses to elevated atmospheric CO 2 . 137 refs., 4 figs., 4 tabs

  14. Chemical uranium enrichment with ion exchanger

    International Nuclear Information System (INIS)

    Takeda, Kunihiko; Onitsuka, Hatsuki; Obanawa, Heiichiro

    1991-01-01

    The uranium enrichment by using ion-exchange has been studied and developed since 1972. The ion-exchange rate has been improved approx. 3000 times and the electron exchange reaction, which occurs with ion-exchange reaction, was also accelerated with catalyst. Flow disturbance in a ion-exchange column has been fully studied and the value of turbulence has been reduced to 150μm. These results allowed us to design a very fine separation column, in which about 10000 stages can be obtained even when the column is more than 1 m in diameter. In the course of the development, a self-regenerating reaction between the redox agents was discovered and incorporated into the process, and has resulted in a reduction of 70 % in the separation energy requirement. (author)

  15. United States enrichment supply - policy and direction

    International Nuclear Information System (INIS)

    Voigt, W.R. Jr.; Peske, S.E.

    1982-01-01

    Recognizing our position as the leader in commercial enrichment services, DOE has established a flexible approach to meeting changing market realities and customer needs. The major elements of this strategy are aggressive deployment of advanced technologies, more flexible contract terms and conditions, and near-term production optimization, all of which are based on a supply strategy which carefully balances near-term requirements with long-range responsibilities. The current surplus of separative work in the world market may afford some near-term opportunities for economy. However, a secure nuclear energy system must be based on assured long-term supply availability at reasonable prices. By utilizing the flexibilities of our large production base and maintaining our demonstrated technological advantages, DOE is confident that the US will continue to be a vital and major competitor in the international nuclear fuel market. 4 figures

  16. Economic evaluation of laser enrichment plant

    International Nuclear Information System (INIS)

    Arisawa, Takashi; Shiba, Koreyuki

    1983-08-01

    Operational characteristics of Laser Enrichment Plant are described based on the data available at present. And its economy is also discussed from the view point of investment and energy consumption. In the procedure of this estimation, the composition of the plant is firstly considered, secondly each component is designed, and thirdly the production cost of each component is estimated. Then the sensitivity of the component cost on the plant cost is analysed, which leads to the optimization of the product cost and the determination of the economic plant size, etc. The results shows that the power cost of the electric gun occupies the large majority of the total power cost, and that the capital cost of laser devices occupies most of the total capital cost. (author)

  17. Response of the brain to enrichment

    Directory of Open Access Journals (Sweden)

    MARIAN C. DIAMOND

    2001-06-01

    Full Text Available Before 1960, the brain was considered by scientists to be immutable, subject only to genetic control. In the early sixties, however, investigators were seriously speculating that environmental influences might be capable of altering brain structure. By 1964, two research laboratories proved that the morphology and chemistry or physiology of the brain could be experientially altered (Bennett et al. 1964, Hubel and Wiesel 1965. Since then, the capacity of the brain to respond to environmental input, specifically "enrichment,'' has become an accepted fact among neuroscientists, educators and others. In fact, the demonstration that environmental enrichment can modify structural components of the rat brain at any age altered prevailing presumptions about the brain's plasticity (Diamond et al. 1964, Diamond 1988. The cerebral cortex, the area associated with higher cognitive processing, is more receptive than other parts of the brain to environmental enrichment. The message is clear: Although the brain possesses a relatively constant macrostructural organization, the ever-changing cerebral cortex, with its complex microarchitecture of unknown potential, is powerfully shaped by experiences before birth, during youth and, in fact, throughout life. It is essential to note that enrichment effects on the brain have consequences on behavior. Parents, educators, policy makers, and individuals can all benefit from such knowledge.Antes de 1960, os cientistas consideravam o encéfalo como imutável, sujeito apenas ao controle genético. Entretanto, no início dos anos 60, alguns pesquisadores especulavam seriamente que influências ambientais podiam ser capazes de alterar a estrutura cerebral. Por volta de 1964, dois laboratórios de pesquisa demonstraram que a morfologia e a química ou a fisiologia do cérebro poderia ser modificada pela experiência (Bennett et al. 1964, Hubel e Wiesel 1965. Desde então, a capacidade do cérebro a responder para responder a

  18. Dimensional enrichment of statistical linked open data

    DEFF Research Database (Denmark)

    Varga, Jovan; Vaisman, Alejandro; Romero, Oscar

    2016-01-01

    On-Line Analytical Processing (OLAP) is a data analysis technique typically used for local and well-prepared data. However, initiatives like Open Data and Open Government bring new and publicly available data on the web that are to be analyzed in the same way. The use of semantic web technologies...... for this context is especially encouraged by the Linked Data initiative. There is already a considerable amount of statistical linked open data sets published using the RDF Data Cube Vocabulary (QB) which is designed for these purposes. However, QB lacks some essential schema constructs (e.g., dimension levels......) to support OLAP. Thus, the QB4OLAP vocabulary has been proposed to extend QB with the necessary constructs and be fully compliant with OLAP. In this paper, we focus on the enrichment of an existing QB data set with QB4OLAP semantics. We first thoroughly compare the two vocabularies and outline the benefits...

  19. Chemical enrichment in halo planetary nebulae

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Peimbert, S; Rayo, J F; Peimbert, M [Universidad Nacional Autonoma de Mexico, Mexico City. Inst. de Astronomia

    1981-01-01

    Photoelectric spectrophotometry of emission lines in the 3400-7400 A region is presented for the planetary nebulae 108-76/sup 0/1(BB1). From these observations the relative abundances of H, He, C, N, O and Ne are derived. The abundances of the halo PN (BB1, H4-1 and K648) are compared to those predicted by stellar evolution theory under the assumption that the envelope has the chemical composition of the matter located between the H burning shell and the surface. The observed He/H and C/O values are higher than predicted which implies that halo PN contain matter from deeper layers than the H burning shell. Furthermore, the O/Ar, N/Ar and Ne/Ar values in halo PN are higher than in the solar neighbourhood, at least part of this enrichment is produced by the PN progenitors.

  20. A reading enrichment program for gifted adolescent

    Directory of Open Access Journals (Sweden)

    Silvia Morales Silva

    2008-06-01

    Full Text Available This descriptive research examines the performance on reading comprehension of four gifted adolescents participating in a reading enrichment program. This performance is related to the variables associated to the gifted performance following the model developed by Mönks: motivation, creativity, high ability, school, peers and family. Results showed that school does not satisfy the cognitive needs of these students and it does not offer the required social support either. The family provides the main social support. The motivation, creativity, the high level of language and concentration of the participants facilitate learning. The reading program is described by the participants as motivating due to the subject-matters and methodology; furthermore, due to the opportunity to deal with peers who have a similar cognitive level.