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Journal Articles

Continuous operation test at engineering scale uranium crystallizer

Washiya, Tadahiro; Tayama, Toshimitsu; Nakamura, Kazuhito*; Yano, Kimihiko; Shibata, Atsuhiro; Nomura, Kazunori; Chikazawa, Takahiro*; Nagata, Masanobu*; Kikuchi, Toshiaki*

Journal of Power and Energy Systems (Internet), 4(1), p.191 - 201, 2010/02

Japan Atomic Energy Agency (JAEA) and Mitsubishi Materials Corporation (MMC) are developing the crystallization process for elemental technology of FBR fuel reprocessing. The uranium (U) crystallization process is a key technology for New Extraction System for TRU Recovery (NEXT) process that was evaluated as the most promising process for future FBR reprocessing. We had developed an innovative crystallizer and fabricated an engineering-scale crystallizer and have carried out continuous operation test to investigate the stability of the equipment at steady and non-steady state conditions by using depleted uranium. As for simulating typical failure events in the crystallizer, crystal accumulation and crystal blockage were occurred intentionally, and monitoring method and resume procedure were tried and selected in this work.

Journal Articles

Experimental determination of distribution behavior of radionuclides in the presence of colloidal substance

Kuno, Yoshio; Morooka, Koichi*; Sasamoto, Hiroshi; Yui, Mikazu

Genshiryoku Bakkuendo Kenkyu, 15(2), p.117 - 129, 2009/03

In the performance assessment of the geological disposal of radioactive wastes, the retardation of radionuclide migration is generally evaluated by using sorption distribution coefficient (Kd). The Kd values would, however, be influenced by the presence of colloidal substance in aqueous phase because these colloids may have the potential abilities to sorb the radionuclides. In this study, Cs-137, bentonite colloids and quartz sands were used for the batch-type sorption tests in order to investigate the influence of colloids on the sorption behavior of radionuclides. The Kds of Cs-137 onto quartz sands (Kd$$_{1}$$) and bentonite colloids (Kd$$_{2}$$) were determined from the distributed amounts in solid phase, colloidal phase and aqueous phase, which were distinguished by the pore size of filters used for the separation of experimental solutions. Distribution behavior of radionuclides in the coexistence of quartz sands and bentonite colloids was able to be evaluated from the Kd$$_{1}$$ and Kd$$_{2}$$ those were obtained from other sorption tests carried out in the separate presence of sands and colloids. To select a suitable filtration method for the separation of the colloidal solutions enables to estimate the influence of colloids on the sorption behavior of radionuclides to solid phase.

Journal Articles

Development of the volume reduction treatment of solid waste system by ultra-high frequency induction furnace

Sakakibara, Tetsuro; Aoyama, Yoshio; Yamaguchi, Hiromi; Sasaki, Naoto*; Nishikawa, Takeshi*; Murata, Minoru*; Park, J.*; Taniguchi, Shoji*; Fujita, Michiru*; Fukuda, Tomoyuki*; et al.

Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 15 Pages, 2009/03

The volume reduction treatment of solid waste system by ultra-high frequency induction furnace (UHFIF) was developed from FY2005 to FY2007. Basic data for melting performance were collected by non-radioactive experiments using the bench scale UHFIF with a crucible capacity of 10 liters. Based on the obtained data, engineering specifications were evaluated for a demonstration scale UHFIF with a crucible capacity of 30 liters. A new demonstration scale UHFIF was constructed and melting experiments of surrogate wastes were carried out by this furnace. It was confirmed that the demonstration scale UHFIF can melt ferrous metal, ceramics and aluminum all together and stabilize aluminum by oxidation to alumina. Density, chemical composition, and surface condition of the solidified substances were analyzed, and homogeneity of the solidified substances was confirmed. Melting behavior in the demonstration scale UHFIF was analyzed by computer simulation and simulation results agreed well with the experimental ones. From the design study for a full scale UHFIF with a crucible capacity of 100 liters, basic specifications were evaluated for the full scale UHFIF. Based on the obtained specification, melting behavior in the full scale UHFIF was analyzed by computer simulation.

Journal Articles

Batch crystallization of uranyl nitrate

Chikazawa, Takahiro*; Kikuchi, Toshiaki*; Shibata, Atsuhiro; Koyama, Tomozo; Homma, Shunji*

Journal of Nuclear Science and Technology, 45(6), p.582 - 587, 2008/06

 Times Cited Count:17 Percentile:22.23(Nuclear Science & Technology)

Batch crystallization of uranyl nitrate is carried out in order to obtain fundamental data required for the development of reprocessing involving crystallization. Particular attention is paid to the development of a method for predicting the concentrations of uranium and nitric acid in the mother liquor and the amount of uranyl nitrate crystals produced. Initial concentrations of uranyl nitrate and nitric acid are 500-600 g/dm$$^{3}$$ and 4-6 mol/dm$$^{3}$$, respectively, corresponding to the condition of a dissolver solution of spent fuel. Steady-state mass balance equations including the correlation equation for the equilibrium solubility of uranium nitrate are applied to the prediction. The calculated concentrations of uranium and nitric acid are in close agreement with the experimental ones. The recovery of uranium is accurately predicted by the calculated concentrations, with an error of less than 5%.

Journal Articles

Flowsheet study of U-Pu Co-crystallization reprocessing system

Homma, Shunji*; Ishii, Junichi; Kikuchi, Toshiaki*; Chikazawa, Takahiro*; Shibata, Atsuhiro; Koyama, Tomozo; Koga, Jiro*; Matsumoto, Shiro*

Journal of Nuclear Science and Technology, 45(6), p.510 - 517, 2008/06

 Times Cited Count:11 Percentile:35.5(Nuclear Science & Technology)

U-Pu co-crystallization reprocessing system is proposed for LWR fuels and its flowsheet study is carried out. This reprocessing system is based on the experimental evidence indicating that hexavalent plutonium is co-crystallized with uranyl nitrate. The system consists of five steps: dissolution of spent fuel, Pu oxidation, U-Pu co-crystallization, dissolution of the crystals, and U crystallization. The system does not require organic solvent, expecting the enhancement of safety and cost-effectiveness. The system requires a recycling of the mother liquor from the U-Pu co-crystallization step to recover almost entire amount of U and Pu. The appropriate recycle ratio is determined for LWR fuels, such that the satisfactory decontamination is achieved. The mother liquor from the U re-crystallization step contains U and Pu. The flowsheet study shows that the constant ratio of Pu to U in the mother liquor can be controlled even though the composition of the spent fuel is different.

Journal Articles

A Study on precipitation behavior of plutonium and other transuranium elements with N-cyclohexyl-2-pyrrolidone for development of a simple reprocessing process

Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Ikeda, Yasuhisa*; Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

Journal of Nuclear Science and Technology, 44(3), p.354 - 360, 2007/03

 Times Cited Count:12 Percentile:31.82(Nuclear Science & Technology)

Precipitation behavior of Pu and other transuranium elements with N-cyclohexyl-2-pyrrolidone (NCP) has been examined to develop a simple reprocessing based only on precipitation method. From HNO$$_{3}$$ solutions containing only Pu, both Pu(VI) and Pu(IV) were precipitated with NCP, but they required more NCP than in the U(VI) precipitation. Selective U(VI) precipitation from HNO$$_{3}$$ solution containing U(VI) and Pu(IV) was achieved by stirring the solution for sufficient time after addition of NCP with ratio of [NCP]/[U]=1.4. Addition of an enough amount of NCP to U(VI)-Pu(VI) or U(VI)-Pu(IV) solutions gave a quantitative precipitation of both U and Pu. Neither Am(III) nor Np(V) was precipitated in the selective U precipitation and the simultaneous U-Pu precipitation. These results demonstrate the feasibility of the reprocessing by precipitation with NCP.

Journal Articles

Measurement of interaction forces between montmorillonite particles in NaCl solutions using a colloidal probe atomic force microscopy

Kurosawa, Susumu; Mizukami, Masashi*; Sato, Hisao*; Nozawa, Jun*; Tsujimoto, Keiichi*; Kurihara, Kazue*

Nippon Genshiryoku Gakkai Wabun Rombunshi, 5(3), p.251 - 256, 2006/09

no abstracts in English

Journal Articles

Effect of the heat treatment conditions onto characteristics of Chromium-Zirconium Copper

Aoki, Shoji*; Wada, Masahiko*; Yamaji, Tetsuo*; Mori, Kensuke; Enoeda, Mikio; Hirose, Takanori; Suzuki, Kazuhiko

Do To Dogokin, 45(1), p.125 - 130, 2006/08

Chromium-zirconium copper (Cu-Cr-Zr) as precipitation hardened copper alloy is examined as one of the structural materials used for the ITER in vacuum vessel components (blanket and divertor etc.). The precipitation hardening in Cu-Cr-Zr is made by the solution treatment with rapid cooling to obtain the supersaturated solid solution of chromium and zirconium in copper, and the subsequent aging treatment to grow the refined precipitate consists of chromium and zirconium respectively. While the parts have been assembled and used by copper alloys already precipitation hardened in general use, the blanket parts will be done by the innovative method with the thermomechanical treatment set of the precipitation hardening at the same time as dissimilar material junction in the ITER blanket. In this research, the mechanical and electrical conductivity properties change was investigated under the wide range of thermomechanical treartment conditions in order to comprehend the conditions necessary to fulfill the excellent characteristics in Cu-Cr-Zr. Therefore, the influence of the quenching cooling rate condition after solution treatment and the other conditions on Cu-Cr-Zr was inspected by measuring electrical conductivity as the indication of the solution treatment state i.e. the supersaturated solid solution or the precipitation state and measuring the tensile test properties of the specimens that are prepared by the set of the solution treatments with some quenching cooling rate conditions and following aging treatments.

Journal Articles

Development of crystallizer for advanced aqueous reprocessing process

Washiya, Tadahiro; Kikuchi, Toshiaki*; Shibata, Atsuhiro; Chikazawa, Takahiro*; Homma, Shunji*

Proceedings of 14th International Conference on Nuclear Engineering (ICONE-14) (CD-ROM), 7 Pages, 2006/07

The crystallization is an advanced and remarkable technology in the future reprocessing process, which requires safety and cost advantages. Japan Atomic Energy Agency (JAEA), Mitsubishi Materials Corporation and Saitama University have been developing an annular-type continuous crystallizer. This paper mainly discussed about this crystallizer design and its development. JAEA has considered following two application processes of the crystallization technology. One is a uranium crystallization process, which applied before the solvent extraction process to recover excessive uranium from dissolver solution and reducing the throughput in the later extraction process. In this process, highly concentrated dissolver solution (about 500g-HM/L) is fed to this crystallizer, and only uranium is crystallized. Another is a plutonium co-crystallization process, which consists of two crystallization steps and excludes extraction process, and thus it's expected to reduce the waste generation and to improve operation safety. In this process, plutonium is co-crystallized with uranium in the first step and separated from residual solution, then the crystals are dissolved into nitric acid solution and excessive uranium is crystallized in the second step. This residual solution is recycled to fuel dissolution process, thus it contributes to reduce nitric acid quantity consumption. For both crystallization processes, same crystallizer design can be applied; we have developed a continuous crystallization system to establish high process throughput and optimizing of the crystallization processes. In the design study of the crystallizer, an annular-type was selected as the most promising design. The fundamental data was obtained by scale-down test device with uranium conditions, and an engineering scale crystallizer was fabricated to confirm the system performance in engineering scale.

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Precipitation behaviors of plutonium and other transuranium elements

Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Ikeda, Yasuhisa*; Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10

N-cyclohexyl-2-pyrrolidone (NCP) can selectively precipitate U(VI) ions in aqueous nitric acid solutions. Utilizing this property, we have been developing a simple reprocessing process of spent nuclear fuel based only on precipitation method. In the first precipitation step, only U is separated by precipitation in a yield of about 70%, and in the second precipitation step both U and Pu are recovered and separated from fission products (FP) and other transuranium elements (TRU). In JAERI, precipitation behaviors of Pu and other TRU were examined experimentally, and the results showed the feasibility of the process establishement.

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Engineering studies for precipitating and separating systems

Yamasaki, Kazuhiko*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*; Kikuchi, Toshiaki*; Morita, Yasuji; Kawata, Yoshihisa*; Mineo, Hideaki; Koshino, Nobuyoshi*; Asanuma, Noriko*; Harada, Masayuki*; et al.

Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 4 Pages, 2005/10

N-cyclohexyl-2-pyrrolidone (NCP), can selectively precipitate U(VI) ions in aqueous nitric acid solutions. Utilizing this property, we have been developing a simple reprocessing process of spent nuclear fuel based only on precipitation method. In the first precipitation step, only U is separated by precipitation in a yield of about 70%, and in the second precipitation step both U and Pu are recovered and separated from fission products (FP) and other transuranium elements (TRU). In the present study, a precipitator and a precipitate separator were designed and built up, and were tested with aspets of operationability and system performance.

JAEA Reports

Study of Subsurface Disposal Concepts for Uranium Waste

Yamamoto, Masayuki*; Ishibashi, Makoto*

JNC-TJ8440 2005-001, 72 Pages, 2005/03

JNC-TJ8440-2005-001.pdf:0.49MB

Uranium waste has features that the main nuclide is long-lived uranium and it is not almost necessary to consider radiation influence from waste package. Although the many studies for subsurface disposal concept of uranium waste have been done, the wastes features were not carefully considered in the former studies. The following reasonable disposal concepts have been designed considering the features in this study. (1) Concrete vault disposal concept in rock cavern (2) Monolithic disposal concept in rock cavern (3) Trench disposal concept in rock cavern / The safety of the disposal concepts during operation and after control phase has been investigated in this study. As the result, it has been shown that the exposure dose of workers due to waste package is not high. And it has been shown that the exposure dose of the public does not change so much, even if the engineered barrier has been reduced. Besides some issues regarding regulation, operation and monitoring have been picked up.

Journal Articles

A Structural study on uranyl (VI) nitrate complexes with cyclic amides; ${it N-n}$-butyl-2-pyrrolidone, ${it N}$-cyclohexylmethyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidone

Koshino, Nobuyoshi*; Harada, Masayuki*; Nogami, Masanobu*; Morita, Yasuji; Kikuchi, Toshiaki*; Ikeda, Yasuhisa*

Inorganica Chimica Acta, 358(6), p.1857 - 1864, 2005/03

 Times Cited Count:49 Percentile:11.49(Chemistry, Inorganic & Nuclear)

Structural analyses of UO$$_{2}$$(NO$$_{3}$$)$$_{2}$$L$$_{2}$$ [L=${it N-n}$-butyl-2-pyrrolidone, N-cyclohexylmethyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidone] have been carried out using X-ray diffraction method. These uranyl complexes were found to have a hexagonal bipyramidal structure. The bond distances of U=O and U-O (ligand), and bond angles of U-O-C(carbonyl) are determined. In uranyl nitrate complexes with cyclic amides such as 2-pyrrolidone, urea, and caprolactam derivatives, a linear correlation was found to hold between U-O (ligand) bond distances and U-O-C(carbonyl) bond angles. Vibrational frequencies of UO$$_{2}$$(NO$$_{3}$$)$$_{2}$$L$$_{2}$$ have also been measured by IR and Raman spectrophotometers. Using relationships between vibrational frequencies of O=U=O bonds and donor numbers (DNs) of ligands, donicities of N-substituted-2-pyrrolidones were determined.

JAEA Reports

Investigation of small scale sphere-pac fuel fabrication plant with external gelation process

Maekawa, Kazuhiko*; Yoshimura, Tadahiro*; Kikuchi, Toshiaki*; Hoshino, Yasushi*; Munekata, Hideki*; Shimizu, Makoto*

JNC-TJ9420 2005-004, 284 Pages, 2005/02

JNC-TJ9420-2005-004.pdf:11.56MB

In feasibility studies on commercialized FBR cycle system, comprehensive system investigation and properties evaluation for candidate FBR cycle systems have been implemented through view point of safety, economics, environmental burden reduction, non-proliferation resistivity, etc. As part of these studies, an investigation of small scale sphere-pac fuel fabrication plant with external gelation process was conducted. Until last fiscal year, equipment layout in cells and overall layout design of the 200t-HM/y scale fuel fabrication plant were conducted as well as schematical design studies on main equipments in gelation and reagent recovery processes of the plant. System property data concerning economics and environmental burden reduction of fuel fabrication plant was also acquired. In this fiscal year, the processes from vibropacking to fuel assemblies storage were added to the investigation range, and a conceptual design of whole fuel fabrication plant was studied as well as deepening the design study on main equipments. The conceptual design study was mainly conducted for small 50t-HM/y scale plant and a revising investigation was done for 200t-HM/y scale Plant. Taking the planed comparative evaluation with pellet fuel fabrication system into account, design of equipments which should be equivalent with pellet system, especially in post-vibropacking processes, were standardized in each system. Based on these design studies, system properties data concerning economics and environmental burden reduction of the plant was also acquired. In comparison with existing design, the cell height was lowered on condition that plug type pneumatic system was adopted and fuel fabrication building was downsized by applying rationalized layout design of pellet system to post-vibropacking processes. Reduction of reagent usage at gelation process and rationalization of sintering and O/M controlling processes etc., are foremost tasks.

JAEA Reports

Investigation into rationalization of low DF pellet fuel fabrication plant configuration Additional Vol. - Study on characteristics evaluation of low DF fuel fabrication systems -

Maekawa, Kazuhiko*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC-TJ9420 2005-003, 280 Pages, 2005/02

JNC-TJ9420-2005-003.pdf:4.73MB

In feasibility studies on commercialized FBR cycle system, a comprehensive system investigation and properties evaluation for candidate FBR cycle systems has been implemented through view point of safety, economics, environmental burden reduction, non-proliferation resistively, etc. As part of these studies, an investigation into rationalization of low decontamination pellet fuel fabrication plant configuration, and a study on characteristics evaluation techniques which focused on plant operating rate and waste generation was conducted. Until last fiscal year, a characteristics evaluation simulator which calculates plant operating rate and waste generation by input failure frequency data and periodic replacement data of every equipment or component was developed, and characteristics comparison between multiple fuel fabrication systems was done by applying it. Character of each fuel fabrication system, concerning system stability represented by waste generation, was shown and challenges in characteristics evaluation were made clear. In this fiscal year, programs of the simulator were modified to reflect plant designs correctly by describing campaign operation and batch treatment in the plant in order to make more quantitative calculation possible. On the other hand, in response to the challenges in the characteristics evaluation of last fiscal year, the system properties data based on a certain standard were acquired in conceptual design study and database were created with view of inter-system comparison. As the results of comparison between pellet system and sphere-pac system using simulator, it was suggested that system stability of pellet system is higher than sphere-pac system, and pellet system is also better in environmental burden reduction, because waste generation of sphere-pac system is apparently larger than pellet system.

JAEA Reports

Investigation into rationalization of low decontamination pellet fuel fabrication planat configuration

Maekawa, Kazuhiko*; Yoshimura, Tadahiro*; Hoshino, Yasushi*; Munekata, Hideki*; Tamaki, Yoshihisa*

JNC-TJ9420 2005-002, 221 Pages, 2005/02

JNC-TJ9420-2005-002.pdf:7.16MB

In feasibility studies on commercialized FBR cyde system, a comprehensive system investigation and properties evaluation for candidate FBR cycle systems has been implemented through view point of safety, economics, environmental burden reduction, non-proliferation resistivity, etc. As part of these studies, an investigation into rationalization of low decontamination pellet fuel fabrication plant configuration was carried out Until last fiscal year, conceptual design studies of the fuel fabrication plant in 200t-HM/y scale were conducted, and system properties data concerning economics and environmental burden reduction of fuel fabrication plant was acquired. In addition to this, 50t-HM/y scale plant was also schematically studied. In this fiscal year, a rationalization study on conceptual design of 50t-HM/y scale plant was conducted with main aim of economic improvement, and the 200t-HM/y scale plant design was revised based on the recent R&D progress. The system properties data concerning economics and environmental burden reduction of fuel fabrication plant was also acquired. In both case of the 50t-HM/y and 200t-HM/y scale plant, it was suggested that the equipment costs were reduced in several percentages because of reduction of maintenance equipments and cut in line number at the pellet fabrication process although granulation process for denitration converted powder and O/M control process for pellets were added. System properties data for comparative evaluation of candidate fuel fabrication systems was also prepared.

JAEA Reports

Estimation Tests for Effecting Factor on Decontamination Property in Crystallization Process

Kusama, Makoto*; Chikazawa, Takahiro*; Tamaki, Yoshihisa*

JNC-TJ8400 2005-006, 88 Pages, 2005/02

JNC-TJ8400-2005-006.pdf:5.67MB

In crystallization unit, UNH (Uranyl Nitrate Hydrate) crystals are washed by a nitric acid solution to get high decontamination factor, but the data on UNH crystals dissolution by washing procedure is insufficient to evaluate the effectiveness of crystallization unit. So, in this study, the effect of a nitric acid concentration to UNH crystals dissolution and decontamination factor was tested. As results, it was found that UNH-crystals dissolution was suppressed as the nitric acid concentration was higher, for example UNH-crystals dissolution by 1N nitric acid washing becomes half as compared with 8N solution washing. And as for the decontamination factor of UNH crystals, it was found that these values by 1N nitric acid washing raised 2-times as compared with 8N nitric acid washing. It was suggested that the decontamination factor of UNH-crystals have the correlation to UNH-crystals dissolution, and shown that UNH crystals loss by washing is 10~20wt% in this experiment.In addition, the crystallization behavior tests used a simulated spent fuel dissolved solution which was prepared by cold FP elements was carried out in a batch-wise experimental method. As results, it was found that in the condition of the feed solution in process design study, Ba element is crystallized with UNH, but other elements were remained in mother liquid. Besides, in the condition of the feed solution contained extreme quantity of Cs than process design concentration, it was found that Cs element was crystallized with UNH. On the other hand, the decontamination factor of other elements except Ba and Cs was about 10 after crystal-liquid separation by filtration, and then increased about 100 after crystal washing. It was confirmed that UNH crystal purity was increased by crystal-liquid separation and washing procedure.

JAEA Reports

Studies on Data Base Management for Nuclide Migration and Improvement of Individual Models (II) (Summary)

Tsujimoto, Keiichi*; Miura, Fusae*; Morooka, Koichi*; Ueda, Shinzo*

JNC-TJ8400 2004-021, 75 Pages, 2005/02

JNC-TJ8400-2004-021.pdf:1.31MB

Methods of management of database which was based on understanding of phenomena, reliable, and closely related with performance assessment were studied on parallel with researches for individual model improvement by means of literature survey, column experiment, and analysis code development.For future management of JNC-TDB was discussed with the latest literatures. Collaboration with outer organization was considered necessary especially on authorization of the TDB. One of the outer organizations could be found in geo-thermal research field.For future management of JNC-SDB, sorption ithotherm of Np on bentonite was tested, and the consistency of the data in SDB was found. A semi-quantitative evaluation method of the reliability of the data was developed and tested with the sorption of Pu and Ni on bentonite. The result shows moderateness of the method and some literature data was considered unreliable by the evaluation.From the literature survey of ir/reversibility of nuclide sorption on colloid showed that apparent irreversibility may often be caused by slow kinetics. Additionally, some general recommendation on the system to be studied was discussed.The column experiment of Sr migration facilitated by colloid through porous media was carried out and analysed by COLFRAC-MRL code. The code was developed to simulate the colloid facilitated migration through porous media.

JAEA Reports

Studies on Data Base Management for Nuclide Migration and Improvement of Individual Models (II)

Tsujimoto, Keiichi*; Miura, Fusae*; Morooka, Koichi*; Ueda, Shinzo*

JNC-TJ8400 2004-020, 294 Pages, 2005/02

JNC-TJ8400-2004-020.pdf:3.96MB

Methods of management of database which was based on understanding of phenomena, reliable, and closely related with performance assessment were studied on parallel with researches for individual model improvement by means of column experiment, and analysis code development for colloids.For nuclide transport database, the basic data development method was examined in order to improve the credibility of the data stored in the database.For the analysis and code development for colloid transport, user interface of the colloid transport analysis code, COLFRAC-MRL code, that was developed in the last year, was developed. The dose analysis based on the nuclide transport analysis with considering colloids are executed by using COLFRAC-MRL code. The effect of chemical equilibrium and kinetics model for nuclide sorption on colloids are evaluated in the analysis.The standard measurement method was examined and data was obtained by the experiments for distribution coefficient of nuclide and colloids, which is the important parameter for safety performance assessment of high-level radioactive waste.

Journal Articles

Development of a simple reprocessing process using selective precipitant for uranyl ions; Fundamental studies for evaluating the precipitant performance

Koshino, Nobuyoshi*; Harada, Masayuki*; Morita, Yasuji; Kikuchi, Toshiaki*; Ikeda, Yasuhisa*

Progress in Nuclear Energy, 47(1-4), p.406 - 413, 2005/00

 Times Cited Count:22 Percentile:16.79(Nuclear Science & Technology)

We have developed a simple reprocessing process for spent FBR fuels using N-cyclohexyl-2-pyrrolidone (NCP) which has selective precipitation ability for UO$$_{2}$$$$^{2+}$$ ions. It was confirmed that NCP has sufficient precipitation ability for UO$$_{2}$$$$^{2+}$$ ions, decontamination capability (separation of UO$$_{2}$$$$^{2+}$$ from simulated fission products), and resistance to $$gamma$$-ray radiation in nitric acid solutions. These findings indicate that NCP is applicable to our reprocessing process. We have also evaluated performances of other precipitants such as N-n-propyl-2-pyrrolidone (NProP), N-n-butyl-2-pyrrolidone (NBP), and N-n-butyl-2-pyridone (NBPyr). It was found that higher decontamination factors (DFs) are obtained by using NProP and NBP. This can be interpreted that the hydrophobicity of NProP and NBP is lower than that of NCP. Furthermore, we have obtained an experimental result that the resistance of NBPyr to $$gamma$$-ray radiation is superior to that of NCP.

179 (Records 1-20 displayed on this page)