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Kobayashi, Daisuke; Yamamoto, Masahiko; Nishida, Naoki; Miyoshi, Ryuta; Nemoto, Ryo*; Hayashi, Hiroyuki*; Kato, Keisuke; Nishino, Saki; Kuno, Takehiko; Kitao, Takahiko; et al.
Nihon Hozen Gakkai Dai-18-Kai Gakujutsu Koenkai Yoshishu, p.237 - 240, 2022/07
All gloves attached to glove-box in Tokai Reprocessing Plant have a fixed expiration date and have to be replaced every 4-year. However, degrees of glove deterioration are different depending on its usage environment (frequency, chemicals, radiation, etc.), because of rubber products. Therefore, physical properties such as tensile strength, elongation, hardness of gloves are measured, and the life-time of gloves are estimated. As a result, gloves without any defects in its appearance have enough physical property for acceptance criteria of new glove. The extrapolated physical property of glove is sufficiently larger than the reported values of damaged glove. No deterioration in physical properties of gloves, that are periodically replaced without any defects in its appearance, is observed and the usable life-time of the glove is estimated to be 8 years.
Isozaki, Naohiko; Morimoto, Kenji; Furukawa, Ryuichi; Tsuboi, Masatoshi; Yada, Yuji; Miyoshi, Ryuta; Uchida, Toyomi; Ikezawa, Kazumi*; Kurosawa, Kenji*
Nihon Hozen Gakkai Dai-16-Kai Gakujutsu Koenkai Yoshishu, p.225 - 228, 2019/07
Highly active liquid waste, which is generated by the reprocessing of spent nuclear fuel, is stored in storage tank of Tokai Reprocessing Plant until it is vitrified. The waste solution in the tank is periodically agitated to avoid the precipitation of insoluble residues during the storage. Three way valves and ball valves have been located at the tank for agitation. Radiation dose rate at the valve location is high and operator's radiation exposure become a problem. Therefore, measures to reduce radiation exposure are performed and reported in this presentation.
Suzuki, Kazuyuki; Nakamura, Yoshinobu; Miyoshi, Ryuta; Sugai, Eiji; Hayashi, Shinichiro; Uchida, Toshitsugu*
no journal, ,
The pulse filter used by the dissolution and clarification process of the Tokai Reprocessing Plant uses the sintering metal powder filter. As for the sintering metal powder filter, being jammed is easy to occur by sludge. The basic examination of the sintering laminating wire mesh filter for the sintering metal powder filter was carried out.
Terunuma, Hirotaka; Shimoyamada, Tetsuya; Kogawa, Takayuki; Kikuchi, Hideki; Miyoshi, Ryuta; Yokota, Satoru; Nakamura, Yoshinobu; Hayashi, Shinichiro
no journal, ,
We have developed dissolver cleaning device which can clean up sludge inside dissolver with high pressure water spray. The device has been applied to TRP dissolvers and the sludge has been cleaned up successfully. This allowed smooth solution transfer and stable operation of the dissolvers.
Hata, Katsuro; Suzuki, Kazuyuki; Miyoshi, Ryuta; Sugai, Eiji; Hikita, Keiichi; Nakamura, Yoshinobu; Hayashi, Shinichiro
no journal, ,
The pulse filter of the clarification process used the sintered metal powder filter at Tokai reprocessing plant. It is known that the sintered metal powder filter is easy to be clogged up by sludge. Therefore, we examined the filtration performance of the sintered laminated wire mesh filter which might substitute for the sintered metal powder filter.
Numata, Shinji; Hata, Katsuro; Nakamura, Daishi; Miyoshi, Ryuta; Wakimoto, Fumitsugu; Taguchi, Katsuya
no journal, ,
no abstracts in English
Tokoro, Hayate; Suzuki, Satoshi*; Miyoshi, Ryuta; Sakurai, Yasuhiro; Matsuki, Takuya; Tsutagi, Koichi; Sekine, Megumi; Shimizu, Yasuyuki; Nakamura, Hironobu
no journal, ,
We inserted a newly designed and manufactured thruster into the guide tube of the high active liquid waste storage cell for inspection in the Tokai Reprocessing Plant and measured the dose rate inside the cell. The dose rate distribution measurements using thruster is an unprecedented experiment, we checked job safety, operability of an equipment and relationship between insert distance of dosimeter and measurement position by using isometric scale mock-up equipment in advance. As a result, we implemented dose rate distribution measurement test inside the cell.
-ray dose rate measurement inside the cellSekine, Megumi; Suzuki, Satoshi*; Tokoro, Hayate; Sakurai, Yasuhiro; Miyoshi, Ryuta; Matsuki, Takuya; Yasuda, Takeshi; Tsutagi, Koichi; Nakamura, Hironobu; Tomikawa, Hirofumi
no journal, ,
JAEA is being conducted feasibility study of technology for Pu solution monitoring including fission products (FPs) as a joint research program with U.S. DOE at the High Active Liquid Waste (HALW) Storage Facility in Tokai Reprocessing Plant to address effective and efficient safeguards for reprocessing facilities. This time, calibration for Ion chamber, measurement results of ray dose rate with Ion chamber and applicability to monitoring technology will be reported.
Tokoro, Hayate; Miyoshi, Ryuta; Matsuki, Takuya; Yasuda, Takeshi; Tsutagi, Koichi
no journal, ,
High active liquid waste (HAW) of about 340 m
is stored in the HAW tanks at the Tokai Reprocessing Plant. However there is no effective observation method inside the cell installing the HAW tank since no one can enter because of its high dose rate. This time, by utilizing the existing guide rail, design and manufacture of the new device for observation, optimization of the device by mockup, inside the cell observation and dose rate distribution measurement inside the cell were conducted. As the result, we were succeeded in observation of the HAW tank and measurement of the dose rate distribution inside the cell for the first time. Here we report the results of those approaches.
Miyoshi, Yuma*; Inoue, Hiroyuki*; Mitsui, Seiichiro; Dobashi, Ryuta*
no journal, ,
In Japan, research and studies on direct disposal of spent fuel as an alternative disposal option are underway in order to secure a wide range of options. For direct disposal, a copper-carbon steel composite vessel covered with pure copper, which is expected to provide longer confinement, has been considered in consideration of the time required for sufficient attenuation of C-14, one of the dominant radionuclides in the safety assessment. In this study, the effect of HCO
on the cathodic reaction of pure copper in a fresh groundwater environment with a low oxygen atmosphere was investigated. From the results of polarization measurements using pure copper as a test electrode, it was inferred that HCO promotes the cathodic reaction, which is a hydrogen evolution reaction using H
as an oxidant, by buffering the pH change at the electrode interface in the relatively low current density range, which is assumed to be the cathodic current of corrosion. It is unlikely that HCO acts directly as an oxidant in the cathodic reaction of corrosion. The hydrogen evolution reaction rate on the pure copper surface is relatively low in comparison with the polarization measurements on pure iron and platinum.