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JAEA Reports

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JNC-TY9400 2002-019, 226 Pages, 2002/09

JNC-TY9400-2002-019.pdf:16.3MB

no abstracts in English

JAEA Reports

Development of the system for the estimation of materials flow in pyrochemical reprocessing plant; Characteristic evaluation of the oxide electrowinning plant

; Tozawa, Katsuhiro;

JNC-TN9400 2002-041, 57 Pages, 2002/07

JNC-TN9400-2002-041.pdf:4.76MB

The operation of the plant with the non-aqueous reprocessing technology depends on the materials handling equipment closely. Because the value of decontamination factor of the products in the plant is low, treatment of nuclear materials requires remote operation technology. So the system for the evaluation of materials flow in the plant was built to evaluate the production ability of the plant and to check out the plant operation from the viewpoint of materials flow. The system is only based on information of the treatment abilities of materials handling machines and process installations and the arrangement of process installations in the reprocessing cell that influences a way to operate materials handling machines intensely. Therefore the system can be used to estimate the characteristics of non-aqueous plants that are not in detail design stage. The amount of production and the characteristics of the oxide electrowinning plant (operation term 200days/year, plant capacity 50tHM/year in design) designed in Feasibility Study Phase-1 were estimated using the system. The results show that the practical amount of production of the plant design is about 88% of the designed value. To increase the amount of production, it is more useful to speed up materials handling machine time than to install new installations or to give priority to conduct bottleneck processes. It is because materials handling influences the production ability of the plant deeply.

JAEA Reports

Simulation of a dry reprocessing plant operation

; ; Yoshiuji, Takahiro*

JNC-TN9400 2002-040, 49 Pages, 2002/07

JNC-TN9400-2002-040.pdf:3.39MB

Operations of a dry reprocessing plant are characterized by batch processing with remote-control material handling machines, so plant -wise simulation of their mechanical actions is required to evaluate the overall performance of the plant. Therefore a simulator has been developed using virtual engineering techniques. The results performed in JFY 2001 are as follows: (1)Construction of an operation simulator of a dry-reprocessing plant design. An operation simulator was developed based on the preliminarily conceptual design of the oxide-electrowinning reprocessing plant made at the phase one of the Feasibility Study on Commercialized Fast Reactor Cycle Systems. The simulator is able to correspond changes of the plant design in future. (2)Evaluation of the oxide-electrowinning reprocessing plant design Simulation was performed using the simulator of the preliminarily conceptual design of the oxide-electrowinning reprocessing plant. The results show that the capacity of the plant will be much lower than the designed one (50tHM/y) due to the speed of material handling machines. The results of the parametric survey of gripping and fixing time also show that the plant capacity can attain 94% of the required capacity even if the gripping and the fixing time decrease to zero. This indicates that only increasing the speed is not enough to dissolve the problem.

JAEA Reports

Development of system analysis code for pyrochemical process using molten salt electrorefining part2 ; Cathode processor calculation code with distillation process and parameter surveys using developed analytical model for cooling system of pyrochemical process cell

; Tozawa, Katsuhiro;

JNC-TN9400 2001-094, 114 Pages, 2001/07

JNC-TN9400-2001-094.pdf:10.56MB

This report describes accomplishment of development of a cathode processor calculation code to simulate the mass and heat transfer phenomena with the distillation process and parameter survey using developed analytical model for cooling behavior of the pyrochemical process cell on personal computers. The pyrochemical process using molten salt electrorefining would introduce new technologies for new fuels of particle oxide, particle nitride and metallic fuels. Evaporation calculations using cathode processor calculation code with distillation process, which was developed in 2000, were evaluated. By selecting proper input data (time step, mesh size etc.), the results showed that the present code agreed well for the evaporation rate of cadmium., and the capability of the distillation process design and simulation with the code has been confirmed. Parameter surveys using developed analytical model were performed for the purpose of reflection of cooling system design of the pyrochemical process cell. 4 cases of cooling flow patterns were surveyed at the normal and low flow rate conditions. From the result of parameter surveys, It was shown that the cooling pattern with direct cooling for heating facilities in the lower cen and balk cooling for upper cell is desirable.

JAEA Reports

A conceptual study of the criticality safety design for pyrochemical reprocessing systems

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JNC-TN9400 2001-072, 107 Pages, 2001/06

JNC-TN9400-2001-072.pdf:3.33MB

Pyrochemical reprocessing systems, which are based on the different physical principles from the existing aqueous reprocessing systems, are expected to be the more economical, more reductible of environmental impact and higher proliferation-resistant. Though many researches and experiments for the development of those systems have been done in many countries there are few studies on the criticality safety design. In this study, the criticality safety design are performed for three pyrochemical reprocessing systems, the metal electrorefining process which has been developed by the Argonne National Labolatory (ANL) in the U.S, the oxide electrowinning process which has been developed by the Research Institute of Atomic Reactors (RIAR) in Russia and the fluoride volatility process which has been developed by the ANL in the U.S, the Japan Atomic Energy Reserch Institute (JAERI) in Japan, etc. As a result of this study, the ordinal criticality safety management methods can directly be applied both to the electrowinning process and to the fluoride volatility process. However, for the electrorefiner vessel used in the metal-electrorefining process, the ordinal methods, in which the only one chemical state is supposed for the all fissile nuclide in the individual unit, cannot be applied directly because the different chemical states co-exist in the electrorefiner by the operation. It is proposed the different idea for this case in the study. And these results are useful to design any pyrochemical reprocessing plants. Because subcritical limits are determined by criticality data of simple models in this study, these limits should be reevaluated based on the detailed hardware design. Futhermore, the criticality safety evaluation with the contingency analysis must be performed to certify that the design has an adequate safety clearance to the anticipated anomaly events.

JAEA Reports

Development of the electrorefining analysis code in the dry reprocessing

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JNC-TN9400 2001-060, 73 Pages, 2001/04

JNC-TN9400-2001-060.pdf:2.27MB

The electrorefining using molten salt is employed in some pyrochemical reprocessing systems. The material behavior in this process, however, is not sufficiently clarified because of the lack of experimental data. The objective of this study is to develop the analysis code of the material behavior. There are two kinds of codes for the analysis of electrorefining process. One is based on the model of material behavior in macroscopic region, which calculates the electrical potential distribution and the current density distribution from electrical potential difference between anodes and cathodes, and obtain the amount of deposited material with spatial distribution on cathode surface. The other is based on the model of material behaviors in microscopic region, which calculates material concentrations on cathode surface with the Nernst's equation from cathode electrical potential, and estimates deposition yields to solve the diffusion equation with material concentrations in molten salt and on cathode surface. In this study, the analysis code, that is able to treat material behaviors with the model of ones in macroscopic and microscopic region and consider molten salt flow, has been developed. As a result, it is confirmed that the segregation of the deposit on cathod caused by the current density distribution is disappeared by stirring molten salt and PuO$$_{2}$$ is efficiently recovered in the MOX electrolysis in which Pu4$$^{4+}$$ is oxidized to PuO$$_{2}$$$$^{2+}$$ by O$$_{2}$$ and PuO$$_{2}$$$$^{2+}$$ is reduced by electrochemical reaction.

JAEA Reports

Development of the object-oriented analysis code for the estimation of material balance in pyrochemical reprocessing process (II); Modification of the code for the analysis of holdup of nuclear materials in the process

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JNC-TN9400 2001-059, 51 Pages, 2001/04

JNC-TN9400-2001-059.pdf:1.55MB

Pyrochemical reprocessing is thought to be promising process for FBR fuel cycle mainly from the economical viewpoint. However, the material behavior in the process is not clarified enough because of the lack of experimental data. The authors have been developed the object-oriented analysis code for the estimation of material balance in the process, which has the flexible applicability for the change of process flow sheet. The objective of this study is to modify the code so as to analyze the holdup of nuclear materials in the pyrochemical process from the viewpoint of safeguard, because of the possibility of larger amount of the holdup in the process compared with aqueous process. As a result of the modification, the relationship between the production of nuclear materials and its holdup in the process can be evaluated by the code.

JAEA Reports

An Evaluation of cost reduction advantages of nuclear-fuel-recycling complex

JNC-TN9400 2001-058, 30 Pages, 2001/04

JNC-TN9400-2001-058.pdf:0.99MB

A design study of separate recycling plants was at first carried out based on a recycling complex design. The former is made up of an independently operating reprocessing plant and an independently operating fuel-manufacturing plant, the latter is a complex of reprocessing and manufacturing of nuclear fuel in one building. Comparisons were then made between the separate recycling plants and the recycling complex to clarify cost reduction advantages of the nuclear-fuel-recycling complex. The following results are presented. (1)The separate reprocessing plant requires storage and shipping facilities of its product, and the separate fuel-manufacturing plant requires receiving and storage facilities of the product. (2)The totals of the areas and volumes of the main buildings of the separate plants are about 30% larger than those of the complex. (3)The total of the construction costs of the separate plants is about 30% higher than that of the complex. About a half of the additional cost is due to the addition of the facilities. From the point of view of cost reduction advantages of a recycling complex, the results show that a recycling complex would be built at a reduction of about 20 % from construction costs of separate plants, because storage, shipping, and receiving facilities will be made redundant for the complex. The results also suggest that construction cost reduction of about 10 % would be expected for a recycling plant made up of two buildings that are connected each other with a trench.

JAEA Reports

Investigation of various recoverry systems for Am Cm; Results in 2000

; ;

JNC-TN9400 2001-034, 157 Pages, 2001/01

JNC-TN9400-2001-034.pdf:5.07MB

In Japan Nuclear Cycle Development Institute, the feasibility study has been carried out in order to evaluate various methods of FBR cycle technology and to propose candidate concepts as practical technology. As a part of this, we investigated a process flow diagram and material balance of various recovery systems$$^{*1}$$ for Am and Cm from high level radioactive liquid waste, and we preliminarily evaluated the equipment scale, the cost and waste generation rate of these systems. As a result, it was obtained that these values are about 1.1-1.4, 0.9-1.4 and 1.2-1.5 times, respectively, of the SETFICS process. From these results, the systems we evaluated are considered to be same for the equipment scale at conceptual design stage, and each system is applicable as the recovery system of Am and Cm. But these results suggest that the facility may be much larger than the PUREX plant, in spite of small contents of the materials (Am and Cm) that is to be recovered. Therefore, whichever method is applied to the recovery system of Am and Cm, we need to develop the process in order to make the system more compact and economical. And then, we need to continue to collect information of these systems and new systems and to comparatively evaluate each system. And we should select finally a practical system of recovery for Am and Cm. *1 : various recovery systems to : (1)DIAMEX process + SANEX process (France - CEA) (2)TRPO process + Cyanex process (China) (3)DIDPA process (Japan-JAERI) (4)TALSPEAK process (U.S.A.-ORNL etc.)

JAEA Reports

lnvestigation of recovery system for Am and Cm; Results in 1999

; ; ;

JNC-TN9400 2000-084, 115 Pages, 2000/07

JNC-TN9400-2000-084.pdf:3.24MB

ln JAPAN NUCLEAR CYCLE DEVELOPMENT INSTITUTE, the feasiblity study has been carried out in order to evaluate various methods of FBR cycle technology and to propose candidate concepts of practical technology. As a part of this, we investigated material balance and a process flow diagram of SETFICS process for the recovery system of Am and Cm from high level radioactive liquid waste, and we preliminarily evaluated the equipment scale, the cost and waste generation rate of this system. As a result, it was obtained that these values are about 17, 15 and 10%, respectively, of the recycle plant based on the simplified PUREX process. ln addition, we investigated preliminary flowsheets of 4 recovery systems for Am and Cm, and compared each to each of them. lt was evaluated that the equipment scale of any process was also equivalent. From these results, each system is applicable as the recovery system of Am and Cm. But these results suggest that the facility may be much larger than the PUREX plant, in spite of small contents of the recovery materials in each system. Therefore, whichever method is applied to the recovery system of Am and Cm, we need to develop the process in order to make the system more compact and economical.

JAEA Reports

Study of the quality of vipac oxide fuel obtained by pyro-processing

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JNC-TN9400 2000-054, 84 Pages, 2000/04

JNC-TN9400-2000-054.pdf:7.15MB

This report describes accomplishment of the study on the quality of vipac (vibro-packed) oxide fuel obtained by pyrochemical processing (molten salt electrolytic processing). This study is intended to contribute to the design study of the pyro-reprocessing-vipac fuel recycling system of oxide fuel. In this study, vibro-packing experiment has been conducted using granular U0$$_{2}$$ obtained by molten salt electrolytic processing (cold experiment). The oxide pyro process developed by Research lnstitute of Atomic Reactors (RIAR) is the method in which the sintered oxide is electrically deposited on the cathode at approximately 600$$^{circ}$$C. 0xide granules for vipac fuel are obtained by crushing the oxide deposited on the cathode. This process is also developed as recycle process because it is capable of FP separation. Also in Japan, this process is studied as one of the new FBR fuel recycling systems. ln this study, we made an effort to clarify the mechanisms of vibro-packing of the electrically obtained granules, which influence on the effective parameters of vibro-packing density and fuel particles size distribution in the fuel cladding in case of non-sphere particles of the granules. As a result of the study, smear density of 75% and almost uniform distribution of U0$$_{2}$$ particles have been taken in the experiment, and much knowledge for the improvement of the vibro-packing quality has been found. And the possibility of the smear density over 80% and the uniform distribution of U0$$_{2}$$ particles has been suggested in this study.

JAEA Reports

Desgin study of pyrochemical process operation by using virtual engineering models

; Tozawa, Katsuhiro; ; ; *

JNC-TN9400 2000-053, 99 Pages, 2000/04

JNC-TN9400-2000-053.pdf:7.47MB

This report describes accomplishment of simulations of Pyrochemical Process Operation by using virtual engineering models. The pyrochemical process using molten salt electrorefining would introduce new technologies for new fuels of particle oxide, particle nitride and metallic fuels. This system is a batch treatment system of reprocessing and re-fabrication, which transports products of solid form from a process to next process. As a result, this system needs automated transport system for process operations by robotics. ln this study, a simulation code system has been prepared, which provides virtual engineering environment to evaluate the pyrochemical process operation of a batch treatment system using handling robots. And the simulation study has been conducted to evaluate the required system functions, which are the function of handling robots, the interactions between robot and process equipment, and the time schedule of process, in the automated transport system by robotics. As a result of simulation of the process operation, which we have designed, the automated transport system by robotics of the pyrochemical process is realistic. And the issues for the system development have been pointed out.

JAEA Reports

Development of system analysis code for pyrochemical process using molten salt electrorifining

Tozawa, Katsuhiro; ;

JNC-TN9400 2000-052, 110 Pages, 2000/04

JNC-TN9400-2000-052.pdf:4.39MB

This report describes accomplishment of development of a cathode processor calculation code to simulate the mass and heat transfer phenomena with the distillation process and development of an analytical model for cooling behavior of the pyrochemical process cell on personal computers. The pyrochemical process using molten salt electrorefining would introduce new technologies for new fuels of particle oxide, particle nitride and metallic fuels. The cathode processor calculation code with distillation process was developed. A code validation calculation has been conducted on the basis of the benchmark problem for natural convection in a square cavity. Results by using the present code agreed well for the velocity-temperature fields, the maximum velocity and its location with the benchmark solution published in a paper. The functions have been added to advance the reality in simulation and to increase the efficiency in utilization. The test run has been conducted using the code with the above modification for an axisymmetric enclosed vessel simulating a cathode processor, and the capability of the distillation process simulation with the code has been confirmed. An analytical model for cooling behavior of the pyrochemical process cell was developed. The analytical model was selected by comparing benchmark analysis with detailed analysis on engineering workstation. Flow and temperature distributions were confirmed by the result of steady state analysis. In the result of transient cooling analysis, an initial transient peak of temperature occurred at balanced heat condition in the steady-state analysis. Final gas temperature distribution was dependent on gas circulation flow in transient condition. Then there were different final gas temperature distributions on the basis of the result of steady-state analysis. This phenomenon has a potential for it's own metastable condition. Therefore it was necessary to design gas cooling flow pattern without ...

JAEA Reports

Study of safety aspects for pyrochemical reprocessing systems

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JNC-TN9400 2000-051, 237 Pages, 2000/04

JNC-TN9400-2000-051.pdf:8.14MB

In this study, we have proposed the concept of safety systems (solutions of safety problems) in pyrochemical reprocessing systems (lt consists of pyrochemical reprocessing methods and the injection casting process for the metal fuel fabrication, or vibro-packing process for the oxide fuel fabrication.) which has different concept from the existing PUREX reprocessing method and pellet fuel fabrication process. And we performed its safety evaluations. FoIlowing the present Japanese safety regulations for reprocessing facilities, we pointed out functions, design requirements and equipments relating to its safety systems and picked up subjects. For the survey of safety evaluations, we first selected anticipated events and accident events, and second by evaluated 6the correspondence of the limitation of the public exposure to the accidents above, by using two parameters, the safety design parameter (the filter performance to confine radioactive matelials) and the leak inventory of radioactivities, and last by picked up its problems. ln addition to the above evaluations we performed basic criticality analyses for its systems to utilize these results for the design and evaluation of the criticality safety management system. Thus this study specified the concept of safety systems for pyrochemical reprocessing processes and then issues in order to establish safety design policies (matters which must consider for the safety design) and guides and to advance more definite safety design.

JAEA Reports

The development of mass balance estimation code; The development and the analyzed example with object type code(I)

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JNC-TN9400 2000-034, 48 Pages, 2000/03

JNC-TN9400-2000-034.pdf:1.56MB

The study and the development to put FBR (Fast Breeder Reactor) to practical use have been doing. So many kinds of technologies are investigated to construct nuclear fuel recycle received to the society. The most important aim of reprocessing has been to extract U and Pu from spent fuels effectively, but, now, the demands for reprocessing are many kinds on nuclear fuel recycle system's construction. These need to be accepted sufficiently. The system that consists of electrolysis, extraction, with molten salt and melting metal, volatilization and condensation using the difference of vapor pressure is suggested, because, differently from LWR (Light Water Reactor), FBR can use the low decontamination factor's fuel. When the engineering scale plant is designed, the dry reprocessing has unsolved problems(ex. process flow) because of less demonstrative scale plants of the dry reprocessing than ones of the wet reprocessing. So the analysis and the estimation of mass balance that is most fundamental in the dry reprocessing system's design need to keep up with the system's alteration (to add new processes etc.) flexibly. This study aim is to develop the mass balance estimation code of dry reprocessing that satisfies the demand mentioned above.

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