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JAEA Reports

Removal of spent fuel sheared powder for decommissioning of Main Plant

Nishino, Saki; Okada, Jumpei; Watanabe, Kazuki; Furuuchi, Yuta; Yokota, Satoru; Yada, Yuji; Kusaka, Shota; Morokado, Shiori; Nakamura, Yoshinobu

JAEA-Technology 2023-011, 39 Pages, 2023/06

JAEA-Technology-2023-011.pdf:2.51MB

Tokai Reprocessing Plant (TRP) which shifted to decommissioning phase in 2014 had nuclear fuel materials such as the spent fuel sheared powder, the diluted plutonium solution and the uranium solution in a part of the reprocessing main equipment because TRP intended to resume reprocessing operations when it suspended the operations in 2007. Therefore, we have planned to remove these nuclear materials in sequence as Flush-out before beginning the decommissioning, and conducted removal of the spent fuel sheared powder as the first stage. The spent fuel sheared powder that had accumulated in the cell of the Main Plant (MP) as a result of the spent fuel shearing process was recovered from the cell floor, the shearing machine and the distributor between April 2016 and April 2017 as part of maintenance. Removing the recovered spent fuel sheared powder was conducted between June 2022 and September 2022. In this work, the recovered powder was dissolved in nitric acid at the dissolver in a small amount in order to remove it safely and early, and the dissolved solution was sent to the highly radioactive waste storage tanks without separating uranium and plutonium. Then, the dissolved solution transfer route was rinsed with nitric acid and water. Although about 15 years had passed since previous process operations, the removing work was successfully completed without any equipment failure because of the organization of a system that combines veterans experienced the operation with young workers, careful equipment inspections, and worker education and training. Removing this powder was conducted after revising the decommissioning project and obtaining approval from the Nuclear Regulation Authority owing to operating a part of process equipment.

JAEA Reports

Controlled release of radioactive krypton gas

Watanabe, Kazuki; Kimura, Norimichi*; Okada, Jumpei; Furuuchi, Yuta; Kuwana, Hideharu*; Otani, Takehisa; Yokota, Satoru; Nakamura, Yoshinobu

JAEA-Technology 2023-010, 29 Pages, 2023/06

JAEA-Technology-2023-010.pdf:3.12MB

The Krypton Recovery Development Facility reached an intended technical target (krypton purity of over 90% and recovery rate of over 90%) by separation and rectification of krypton gas from receiving off-gas produced by the shearing and the dissolution process in the spent fuel reprocessing at the Tokai Reprocessing Plant (TRP) between 1988 and 2001. In addition, the feasibility of the technology was confirmed through immobilization test with ion-implantation in a small test vessel from 2000 to 2002, using a part of recovered krypton gas. As there were no intentions to use the remaining radioactive krypton gas in the krypton storage cylinders, we planned to release this gas by controlling the release amount from the main stack, and conducted it from February 14 to April 26, 2022. In this work, all the radioactive krypton gas in the cylinders (about 7.1$$times$$10$$^{5}$$ GBq) was released at the rate of 50 GBq/min or less lower than the maximum release rate from the main stuck stipulated in safety regulations (3.7$$times$$10$$^{3}$$ GBq/min). Then, the equipment used in the controlled release of radioactive krypton gas and the main process (all systems, including branch pipes connected to the main process) were cleaned with nitrogen gas. Although there were delays due to weather, we were able to complete the controlled release of radioactive krypton gas by the end of April 2022, as originally targeted without any problems such as equipment failure.

Journal Articles

Evaluation of Tsunami debris impact on Tokai Reprocessing Plant

Nishino, Saki; Tsuboi, Masatoshi; Okada, Jumpei; Saegusa, Yu; Omori, Kazuki; Yasuo, Kiyoshi; Seshimo, Kazuyoshi; Domura, Kazuyuki; Yamamoto, Masahiko

Nihon Hozen Gakkai Dai-17-Kai Gakujutsu Koenkai Yoshishu, p.541 - 548, 2021/07

no abstracts in English

Journal Articles

Real-time X-ray diffraction of metastable phases during solidification from the undercooled LuFeO$$_{3}$$ melt by two-dimensional detector at 1 kHz

Kumar, M. V.*; Kuribayashi, Kazuhiko*; Nagashio, Kosuke*; Ishikawa, Takehiko*; Okada, Jumpei*; Yu, J.*; Yoda, Shinichi*; Katayama, Yoshinori

Applied Physics Letters, 100(19), p.191905_1 - 191905_4, 2012/05

 Times Cited Count:2 Percentile:8.97(Physics, Applied)

${it In-situ}$ identification of metastable phases formed from the undercooled LuFeO$$_{3}$$ melt under controlled oxygen partial pressure $$P$$o$$_{2}$$ was studied by X-ray diffraction measurements at a synchrotron radiation source. Real-time observation of the formation and growth of individual phases during the single recalescence of Lu$$_{3}$$Fe$$_{2}$$O$$_{7}$$ and LuFe$$_{2}$$O$$_{4}$$ phases at $$P$$o$$_{2}$$ of 1$$times$$10$$^{3}$$ Pa has been revealed by a high speed imaging system at 1 kHz. The obtained diffraction pattern of the metastable phase in the LuFeO$$_{3}$$ system was consistent with that of the metastable and stable phases reported in the Lu-Fe-O system.

Journal Articles

Performance of the main ring BPM during the beam commissioning at J-PARC

Toyama, Takeshi*; Arakawa, Dai*; Hiramatsu, Shigenori*; Igarashi, Susumu*; Lee, S.*; Matsumoto, Hiroshi*; Odagiri, Junichi*; Tejima, Masaki*; Tobiyama, Makoto*; Hashimoto, Yoshinori*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.981 - 983, 2010/05

Experiences of operating BPM's during beam commissioning at the J-PARC MR are reported. The subjects are: (1) bug report, statistics and especially the effect of a beam duct step, (2) position resolution estimation ($$<$$30 micrometers with 1 sec averaging), (3) beam based alignment.

Oral presentation

Development of the SUS310EHP stainless steel having superior corrosion resistance, 2; Inter-granular corrosion tests at the SUS310EHP stainless steel

Kato, Chiaki; Soma, Yasutaka; Ueno, Fumiyoshi; Okada, Kiyotaka*; Ebina, Tetsunari*; Kano, Yoichi*; Nakayama, Jumpei

no journal, , 

no abstracts in English

Oral presentation

Development of the SUS310EHP stainless steel having superior corrosion resistance, 1; Overview of development of the SUS310EHP stainless steel

Sugiyama, Hiroshi*; Okada, Kiyotaka*; Ebina, Tetsunari*; Kano, Yoichi*; Soma, Yasutaka; Kato, Chiaki; Ueno, Fumiyoshi; Nakayama, Jumpei*

no journal, , 

no abstracts in English

Oral presentation

Development of powder recovery technology by laser and examination of applicability toward decommissioning of reprocess plant

Okada, Jumpei; Nishino, Saki; Terunuma, Ryuki; Takahashi, Naoki; Isomae, Hidemi

no journal, , 

no abstracts in English

Oral presentation

Flush-out in the decommissioning project of Tokai Reprocessing Plant

Okada, Jumpei

no journal, , 

no abstracts in English

9 (Records 1-9 displayed on this page)
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