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) by mechanochemical treatmentAkiyama, Daisuke*; Mishima, Tomoki*; Okamoto, Yoshihiro; Kirishima, Akira*
High Temperature Materials and Processes, 42(1), p.20220268_1 - 20220268_9, 2023/04
A powder mixture of UO and TiO was mechanochemically treated in a planetary ball mill under Ar atmosphere for 1 h using a tungsten carbide vial and balls as the milling medium. Such mechanochemical (MC) treatment reduced the crystallinity of UO and TiO. The mechanochemically treated powder mixture was heated at 973-1573K for 6 h under Ar atmosphere and analyzed by X-ray diffraction analysis, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and X-ray absorption fine structure analysis. UTiO did not form below 1373K without MC treatment and only the starting materials were observed. At 1473 and 1573K, a small amount of UTiO and equal amounts of UTiO and UO were formed, respectively. The mechanochemically treated sample produced nearly pure UTiO containing small amounts of UO impurities when heated above 1173K for 6 h. UTiO was highly crystalline and uniform regardless of the synthesis temperature.
Kakehi, Isao;
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 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
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 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 particles has been suggested in this study.
Kakehi, Isao; 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.
Tozawa, Katsuhiro; ; Kakehi, Isao
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 ...
Kakehi, Isao; Nakabayashi, Hiroki
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.
Yumoto, Ryozo*; Yokochi, Yoji*; Koizumi, Masumichi*; Seki, Sadao*
PNC TJ9409 96-002, 93 Pages, 1996/03
The state of development of pyrometallurgical partitioning and extracting technology of irradiated fuel is investigated. Also in case of perfoming the test at O-arai engineering center, the contents of the test, equipments, structure and arragement of cells that equipments are installed, are studied. The purpose of the test is to confirm the realization of the process and behavior of FP and TRU elements, and off-gass that cannot be made dear by cold test. In this study it is assumed that 
100g monju fuel (94,000MWd/t B.U, cooled for 550 days) per batch is treated. Four processes are picked up except for pin sectioning and powdering, as important subjects. They are as follows. (1)reduction of oxide fuel (2)electrorefining (3)cathode processing (4)extraction of TRU elements. And the outline of the test, blocked flow chart and the outline of equipment are clarified. And the outline of chart is drawn. Moreover, the specification of analitical equipments which are necessary to analyze the product is shown. From spent chloride, TRU and a part of FP elements are extracted and they are recycled for electrorefining and so on. The salt-waste including residual FP elements is kept in a receptacle after being absorbed into Zeorite and soldified. As the disposition of these tests, modified test cell in the existing FMF, modified concrete cell in AGF, new cell at B2F in the existing FMF and new cell at second auxiliary room in FMF extension are studied. As result of considering the disposition for equipment, the difficulty of reconstucting new cell including of equipments, method of mentenance, and equipments of ventilazion (Ar circumstance) including of management of off gas, and the plan of disposition, it is concluded that constructing iron cell into the second auxiliary room of FMF extension is best, because it is easy to construct safely, and the occurance of radioactive waste and the influence to other tests is little, and it is possible to examine more efficiently.
*; *; *; *; Namba, Hideki; Tokunaga, Okihiro; Hashimoto, Shoji; *; *
Ebara Jiho, (166), p.56 - 64, 1995/00
no abstracts in English
Tobita, Noriyuki; ; Nogami, Yoshitaka; Nagai, Shuichiro;
PNC TN8410 91-272, 244 Pages, 1991/11
no abstracts in English
; ; ;
JAERI-M 89-142, 48 Pages, 1989/10
no abstracts in English
;
Journal of Nuclear Science and Technology, 11(11), p.488 - 494, 1974/11
Times Cited Count：2no abstracts in English
Shimoyama, Iwao; Hirao, Norie; Baba, Yuji; Izumi, Toshinori; Okamoto, Yoshihiro; Yaita, Tsuyoshi; Suzuki, Shinichi
no journal, ,
We propose a low-pressure sublimation method as a new dry method for reduction of radioactive soil pollutant in Fukushima. We applied heat treatment for weathered biotite saturated and sorbed with 
Cs. Thermogravimetric analysis in low-pressure environment showed a mass decrease due to Cs desorption around 750-800 C, which was not observed in air. Thermal desorption spectroscopy (TDS) showed Cs desorption peak at 680 C in high vacuum environment. This peak shifted to low-temperature side by about 200 C by heating with NaCl-CaCl mixed salt. X-ray fluorescence (XRF) analysis clarified that only negligible amount of Cs was retained in the weathered biotite after heating with the mixed salt at 700 C for two hours. On the other hand, about one-third of Cs can be removed without the salt. These results demonstrated that low-pressure sublimation method can decontamination of Cs from clay minerals using lower temperatures than those for conventional dry methods.
