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Kato, Chiaki
Comprehensive Nuclear Materials, 2nd Edition, Vol.4, p.528 - 563, 2020/08
In spent fuel reprocessing plants, various nitric media are encountered throughout the PUREX process, used in the separation of fission products, uranium, and plutonium. The PUREX process is thus highly corrosive as it takes place at high temperatures under high concentrations of nitric acid solution containing oxidizing metal ions from spent fuel. In this review, the unique chemical properties of nitric acid are first described. Secondly, the process of oxidizing power generation in boiling nitric acid under heat transfer is described using the redox potential and a thermodynamic model of boiling nitric acid. Finally, the corrosion behavior and corrosion acceleration mechanism specific to the reprocessing environments are described from the perspective of solution chemistry.
Uchiyama, Gunzo; Asakura, Toshihide; Hotoku, Shinobu; Mineo, Hideaki; Kamei, Kazushige; Watanabe, Makio; Fujine, Sachio
Journal of Radioanalytical and Nuclear Chemistry, 246(3), p.683 - 688, 2000/12
Times Cited Count：13 Percentile：64.6(Chemistry, Analytical)no abstracts in English
Fujii, Toshiyuki*; *
JNC TJ9400 2000-003, 36 Pages, 2000/02
JNC-TJ9400-2000-003.pdf:1.36MB
For establishing a recycling system based on low-decontamination, the distribution behaviors of radionuclides in the process are essential information for the design of the system. Molybdenum and palladium are less radioactive fission products, but attention should be paid to them because they are likely to extremely affect the performance of the recycled fuels. In this context, in this study, the extraction behaviors of molybdenum and palladium under conditions of PUREX and TRUEX extraction process were experimentally studied, and their chemical mechanisms were discussed. In cojunction with the extraction experiments, absorption spectrometry was applied to identify the related species and the extraction mechanism. As a result, knowledge for the distribution characteristics of molybdenum and palladium in PUREX and TRUEX process was reinforced.
*; *; Fumoto, Hiromichi*; *; *
JNC TJ9400 2000-001, 112 Pages, 2000/02
JNC-TJ9400-2000-001.pdf:6.67MB
The purpose of this study is to investigate the possibility of new reprocessing process for the purpose of introducing pipeless plant concept, where aqueous separation methods other than solvent extraction method are adopted in order to develop more economical FBR fuel (MOX fuel) reprocessing process. At it's first stage, literature survey on precipitation method, crystallization method and ion-exchange method was performed. Based on the results, following processes were candidated for pipeless reprocessing plant. (1)The process adopting crystallization method and peroxide precipitation method (2)The process adopting oxalate precipitation method (3)The process under mild aqueous conditions (crystallization method and precipitation method) (4)The process adopting crystallization method and ion-exchange method (5)The process adopting crystallization method and solvent extraction method The processes (1)
(5) were compared with each others in terms of competitiveness to the conventional reference process, and merits and demerits were evaluated from the viewpoint of applicability to pipeless reprocessing plant, safety, economy, Efficiencies in consumption of Resources, non-proliferation, and, Operation and Maintenance. As a result, (1)The process adopting crystallization method and peroxide precipitation method was selected as the most reasonable process to pipeless plant. Preliminary criticality safety analyses, main process chemical flowsheet, main equipment list and layout of mobile vessels and stations were reported for the (1) process.
Koga, Jiro*; Shinzato, Takushi*
JNC TJ8400 2000-054, 48 Pages, 2000/02
JNC-TJ8400-2000-054.pdf:1.23MB
The "STELLA" which is a tool for simulation of dynamical systems applied to the numerical simulation of the behavior of minor constituent, such as hydrazoic acid, forming and extinguishing on the operation of reprocessing process. The concentration of hydrazoic acid forming by the reaction of nitrite and hydrazine were determined by use of STELLA after the determination of concentration of main constituents by MIXSET-X. The results from simulation is shown that the STELLA is applicable to the numerical simulation of the behavior of minor constituent.
Matsumoto, Shiro*; Tajima, Yasunori*; Koga, Jiro*; Miyahara, Yukari*
PNC TJ1609 98-001, 26 Pages, 1998/02
no abstracts in English
Nemoto, Shinichi; Sakai, Toshiyuki*; Sanyoshi, Hirotaka; Kikuchi, Kenji; Iwasaki, Isao*; Kuribayashi, Masakazu*; Matsushima, Kazumi*
PNC TN8410 93-283, 86 Pages, 1993/11
None
; ;
PNC TN8410 93-006, 38 Pages, 1992/12
Elimination of the ionic platinum group metals (palladium, rhodium, ruthenium) and technetium from dissolver solution seems to be an effective method to improve the stability, reliability and operability of the extraction process in spent nuclear fuel reprocessing. Some fundamental experiments were conducted for the purpose of establishing this new method. A method of electrolytic extraction to separate and recover such metals from Purex process solutions was investigated. Potentiostatic investigations of platinum group metals were carried out to identify deposition starting potential and rate in a nitric acid condition. As the results, it was found that the deposition rate depended on the electrode material, temperature, nitric acid concentration and coexistence ions. The deposition rate were found to be related to the polalization potential, and the optimum deposition potential was specified for each of platinum group metals.
