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JAEA Reports

Irradiation test using foreign reactor, 1; Study of irradiation test with capsule temperature control system (Joint research)

Takabe, Yugo; Otsuka, Noriaki; Fuyushima, Takumi; Sayato, Natsuki; Inoue, Shuichi; Morita, Hisashi; Jaroszewicz, J.*; Migdal, M.*; Onuma, Yuichi; Tobita, Masahiro*; et al.

JAEA-Technology 2022-040, 45 Pages, 2023/03

JAEA-Technology-2022-040.pdf:6.61MB

Because of the decommission of the Japan Materials Testing Reactor (JMTR), the domestic neutron irradiation facility, which had played a central role in the development of innovative nuclear reactors and the development of technologies to further improve the safety, reliability, and efficiency of light water reactors, was lost. Therefore, it has become difficult to pass on the operation techniques of the irradiation test reactors and irradiation technologies, and to train human resources. In order to cope with these issues, we conducted a study on the implementation of irradiation tests using overseas reactors as neutron irradiation sites as an alternative method. Based on the "Arrangement between the National Centre for Nuclear Research and the Japan Atomic Energy Agency for Cooperation in Research and Development on Testing Reactor," the feasibility of conducting an irradiation test at the MARIA reactor (30 MW) owned by the National Centre for Nuclear Research (NCBJ) using the temperature control system, which is one of the JMTR irradiation technologies, was examined. As a result, it was found that the irradiation test was possible by modifying the ready-made capsule manufactured in accordance with the design and manufacturing standards of the JMTR. After the modification, a penetration test, an insulation continuity test, and an operation test in the range of room temperature to 300 $^{circ}$ C, which is the operating temperature of the capsule, were conducted and favorable results were obtained. We have completed the preparations prior to transport to the MARIA reactor.

JAEA Reports

Accident evaluation during transfer of irradiated fuel specimen

Morita, Hisashi; Iimura, Koichi; Matsui, Yoshinori; Takemoto, Noriyuki

JAEA-Technology 2022-024, 73 Pages, 2022/11

JAEA-Technology-2022-024.pdf:1.56MB

JMTR was positioned as a decommissioning facility in the facilities mid- and long-term plan (formulated in April 1, 2017) of the Japan Atomic Energy Agency. On September 18, 2019, we applied for approval of the decommissioning plan for the JMTR reactor facility, and received the approval on March 17, 2021. This made it impossible to conduct irradiation tests with nuclear fuel material at the JMTR using facility. Therefore, on August 7, 2020, in order to delete the description about irradiation test and to change accident evaluation, we applied for change of permission to use nuclear fuel material regarding JMTR facility (Facility No. 1) at the Oarai Research and Development Institute (North Area), and received the permission on May 26, 2021. As the accident evaluation, radiation exposure evaluation was performed at the boundary of the surrounding monitoring area assuming a damage accident during transfer work of the irradiated fuel specimen to the hot laboratory. As a result, it was confirmed to satisfy the standards such as the dose notification concerning about external exposure due to atmospheric diffusion, internal exposure due to atmospheric diffusion, external exposure due to direct -rays and skyshine -rays. This report summarizes the methods and results of the accident evaluation related to permission change of JMTR using facility.

JAEA Reports

Basic design of the Hot Laboratory exhaust stack

Morita, Hisashi; Daigo, Fumihisa; Sayato, Natsuki; Watahiki, Shunsuke; Kojima, Kazuki; Nakayama, Kazuhiko; Ide, Hiroshi

JAEA-Technology 2021-030, 166 Pages, 2022/05

JAEA-Technology-2021-030.pdf:3.65MB

When the roof of the JMTR Hot Laboratory (HL) building was repaired for rain leaks in January, 2015, thinning was found at one of the anchor bolts on base of the HL exhaust stack. Moreover, the thinning of some anchor bolts and gaps between the anchor bolt nuts and flange plate was found in the later investigation for the exhaust stack. Since the possibility of the exhaust stack collapsing cannot be denied, it was removed. Therefore, it became necessary to rebuild a new exhaust stack as soon as possible. The design of the new exhaust stack was based on the measures to prevent rainwater intrusion into the base, which was the cause of the thinning of the anchor bolts found in the investigation, and on the new regulatory standards established after the accident at the Fukushima Daiichi Nuclear Power Station. Furthermore, since the new exhaust stack corresponds to buildings and structures that must undergo building confirmation, the soundness of the new exhaust stack against seismic force and wind load was evaluated based on the Building Standards Law and the Stack Structure Design Guideline. This report described the basic design of the new exhaust stack.

Journal Articles

Characterization and storage of radioactive zeolite waste

Yamagishi, Isao; Nagaishi, Ryuji; Kato, Chiaki; Morita, Keisuke; Terada, Atsuhiko; Kamiji, Yu; Hino, Ryutaro; Sato, Hiroyuki; Nishihara, Kenji; Tsubata, Yasuhiro; et al.

Journal of Nuclear Science and Technology, 51(7-8), p.1044 - 1053, 2014/07

https://doi.org/10.1080/00223131.2014.924446

Times Cited Count：19 Percentile：78.38(Nuclear Science & Technology)

For safe storage of zeolite wastes generated by treatment of radioactive saline water at the Fukushima Daiichi Nuclear Power Station, properties of the Herschelite adsorbent were studied and its adsorption vessel was evaluated for hydrogen production and corrosion. Hydrogen production depends on its water level and dissolved species because hydrogen is oxidized by radicals in water. It is possible to evaluate hydrogen production rate in Herschelite submerged in seawater or pure water by taking into account of the depth effect of the water. The reference vessel of decay heat 504 W with or without residual pure water was evaluated for the hydrogen concentration by thermal hydraulic analysis using obtained fundamental properties. Maximum hydrogen concentration was below the lower explosive limit (4 %). The steady-state corrosion potential of a stainless steel 316L increased with absorbed dose rate but its increase was repressed by the presence of Herschelite. At 750 Gy/h and 60 $^{circ}$ C which were values evaluated at the bottom of the vessel of 504 W, the localized corrosion of SUS316L contacted with Herschelite would not immediately occur under 20,000 ppm of Cl $^{-}$ concentration.

Journal Articles

Safe storage of zeolite adsorbents used for treatment of accident-generated water at Fukushima Daiichi Power Station

Yamagishi, Isao; Nagaishi, Ryuji; Terada, Atsuhiko; Kamiji, Yu; Kato, Chiaki; Morita, Keisuke; Nishihara, Kenji; Tsubata, Yasuhiro; Ji, W.*; Fukushima, Hisashi*; et al.

IAEA-CN-211 (Internet), 5 Pages, 2013/01

http://www-pub.iaea.org/iaeameetings/IEM4/29Jan/Yamagishi.pdf

Since the accident at Fukushima Daiichi Nuclear Power Station, a large amount of radioactive contaminated water has been generated to cool damaged reactor cores. Adsorption of cesium with zeolite-like media was employed for treatment of this contaminated saline water. As spent zeolite media are highly radioactive, their safe storage is a pressing issue. Japan Atomic Energy Agency has extensively conducted R&D on the management of secondary wastes produced by the operation of the treatment system. Subjects on the safe storage of spent zeolites include the analysis of their characteristics and the evaluation of effectiveness of the present safety measures in consideration of decay heat emission and hydrogen generation by water radiolysis as well as durability of vessels exposed to saline. Preliminary results obtained are described in the present paper.

Journal Articles

Be-NMR spin-lattice relaxation rate in heavy-fermion superconductor UBe $_{13}$

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Irradiation test using foreign reactor, 1; Study of irradiation test with capsule temperature control system (Joint research)

Accident evaluation during transfer of irradiated fuel specimen

Basic design of the Hot Laboratory exhaust stack

Characterization and storage of radioactive zeolite waste

Safe storage of zeolite adsorbents used for treatment of accident-generated water at Fukushima Daiichi Power Station

Be-NMR spin-lattice relaxation rate in heavy-fermion superconductor UBe $_{13}$

Irradiation effects on plasma diagnostic components

Irradiation tests on diagnostics components for ITER in 1995

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2nd power-up test for JRR-2

The First loading fuel elements and power-up for JRR-2

Critical experiments and characteristic measurement for JRR-2