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Tanigawa, Masafumi; Nakamura, Daishi; Asakawa, Naoya*; Seya, Kazuhito*; Omori, Fumio*; Koiso, Katsuya*; Horigome, Kazushi; Shimizu, Yasuyuki
JAEA-Technology 2024-001, 37 Pages, 2024/05
JAEA-Technology-2024-001.pdf:2.32MB
At plutonium conversion development facility, the neutralization sedimentation and the coagulation sedimentation (sludge) items are stored in a polyethylene container packed in the plastic bag. The neutralization sedimentation items and the coagulation sedimentation items are stored in the globe box and storage room in the facility, respectively. Some sludge items generate gases, that swelled the plastic bag. We should ensure whether the bag swelling by visual confirmation. When the swelling is confirmed, those containers are transferred to the glove box to exchange the plastic bag for new one. By keeping the above procedure, those items were stored safely in the facility since its founding. The stabilization work for enhance the safe storage was planned to reduce the gas generation of the sludge items caused by the radiolysis of water. Those sludge items have the containing a sodium nitrate that has moisture-absorption characteristic. Therefore, the stabilization method aimed to remove the sodium nitrate from the items. The work was conducted from August 2018 to August 2022. The sodium concentration in items were reduced to 3 wt% or lower. Each stabilized sludge item packed in plastic bag were confirmed its swelling for over one year in the storage place. No gas generation from all item has been observed for more than the one year. And while both the neutralization and the coagulation sedimentation items were stored they were not the increasing of the moisture in the items. As a result, those items were evaluated that will not generate gases any more and confirmed to be stabilized after this treatment. Then, those neutralization sedimentation items were stored in powder cans and transferred to powder storage room as a retained waste. Based on the above results, risks of the gas generation from sludge items were decreased enough. Therefore, the safety of the stored sludge item was improved and confirmed.
Mukai, Yasunobu; Koiso, Katsuya; Nakamura, Hironobu; Hosoma, Takashi; Yoshimoto, Katsunobu; Hayashi, Hiroyuki*
Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-30-Kai Nenji Taikai Rombunshu (CD-ROM), 9 Pages, 2009/11
Electro manometer (ELTM) is a device to measure accurately level, density and volume in an accountability tank for the purpose of nuclear materials accountancy, safeguards and operational control. JAEA have developed and put the ELTM using digiquartz differential pressure transducer into practical use at plutonium conversion development facility since initial tank calibration in 1982. As a result of calibrations and measurements in the last 15 years, the sustainable measurement accuracy is 
2 Pa as a sigma of difference from the standard pressure and 0.002 g/cm
as a sigma of difference from the solution density analytically determined. However, a drift of data we have never experienced was found in 2008. After investigations, a characteristic value T
(period of vibration at zero pressure) which is stable in normal state had changed around 7% at the drift. This was the result of aging, so it was found that monitoring of T value was the very effective information to know the timing of replacement of the transducer. We will present the long-term measurement accuracy of ELTM practically achieved and the way of maintenance including a replacement of the transducer.
Fujiwara, Hideki*; Kamoshida, Shuichi*; Sugaya, Shinichi*; Nakamura, Hironobu; Koiso, Katsuya; Yoshimoto, Katsunobu
no journal, ,
no abstracts in English
Isomae, Hidemi; Nakamura, Hironobu; Matsumoto, Masaki; Kato, Yoshiyuki; Nakamichi, Hideo; Koiso, Katsuya*; Shoji, Kaoru*
no journal, ,
Ring monitor by glass dosimeter was designed and applied to the radiation management for glove box operation. The radiation management method and the irradiation test results are introduced in this report.