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Kochiyama, Mami
Kaku Deta Nyusu (Internet), (133), p.76 - 81, 2022/10
The outline of the presentation at the joint session of Research Committee for Nuclear Data and Subcommittee on Nuclear Data in the Atomic Energy Society of Japan 2022 Autumn Meeting was contributed to Nuclear Data News. As part of the study on the near surface disposal of waste from research facilities, we are studying a method for evaluating the radioactivity inventory of waste generated by the dismantling of research reactors. In the radioactivity evaluation of the research reactor, we have investigated the method of calculating the neutron transport in the reactor and using the obtained neutron spectrum to calculate the activation of the internal structure by the ORIGEN-S code. In recent years, we have introduced and evaluated libraries created based on JENDL-4.0 and JENDL/AD-2017, and we will introduce the status of their examination. And we will introduce how to apply the results obtained by the radioactivity evaluation calculation to burial disposal.
Okada, Shota; Murakami, Masashi; Kochiyama, Mami; Izumo, Sari; Sakai, Akihiro
JAEA-Testing 2022-002, 66 Pages, 2022/08
JAEA-Testing-2022-002.pdf:2.46MB
Japan Atomic Energy Agency is an implementing organization of burial disposal for low-level radioactive waste generated from research, industrial and medical facilities in Japan. Radioactivity concentrations of the waste are essential information for design of the disposal facility and for licensing process. A lot of the waste subjected to the burial disposal is arising from dismantling of nuclear facilities. Radioactive Wastes Disposal enter has therefore discussed a procedure to evaluate the radioactivity concentrations by theoretical calculation for waste arising from the dismantling of the research reactors facilities and summarized the common procedure. The procedure includes evaluation of radioactive inventory by activation calculation, validation of the calculation results, and determination of the disposal classification as well as organization of the data on total radioactivity and maximum radioactivity concentration for each classification. For the evaluation of radioactive inventory, neutron flux and energy spectra are calculated at each region in the reactor facility using two- or three-dimensional neutron transport code. The activation calculation is then conducted for 140 nuclides using the results of neutron transport calculation and an activation calculation code. The recommended codes in this report for neutron transport calculation are two-dimensional discrete ordinate code DORT, three-dimensional discrete ordinate code TORT, or Monte Carlo codes MCNP and PHITS, and for activation calculation is ORIGEN-S. Other recommendation of cross-section libraries and calculation conditions are also indicated in this report. In the course of the establishment of the procedure, Radioactive Wastes Disposal Center has discussed the commonly available procedure at meetings. It has periodically held to exchange information with external operators which have research reactor facilities. The procedure will properly be reviewed and be revised by reflecting future situ
Suzuki, Masafumi*; Yoshinaka, Kazuyuki
Gijutsushi, (648), p.12 - 15, 2020/12
The site tour which is a part of CPD events regarding the issue concerning the radioactive waste from nuclear facilities was organized in autumn 2019, and we visited the facilities related to the specified waste due to the Fukushima-Daiichi Nuclear Power Plant accident in spring 2020. The tours made us reacknowledge the impact of radionuclides on environment at accident, the importance of the management of nuclear facilities under the basic premise of ensuring safety, the necessity of the discussion based on the common understanding, and that would be contributed to find the solution of those issues.
Izumo, Sari; Hayashi, Hirokazu; Nakata, Hisakazu; Amazawa, Hiroya; Motoyama, Mitsushi*; Sakai, Akihiro
JAEA-Technology 2018-018, 39 Pages, 2019/03
JAEA-Technology-2018-018.pdf:2.8MB
JAEA has planed the near surface disposal of LLW generated from research, industrial, and medical facilities. Maximum radioactivity concentration of each waste and total radioactivity of disposed wastes are needed to be less than the permitted values in the license of disposal facility. Thus, it is important not to evaluate the radioactivity of each waste in unduly conservative ways so as to dispose of the total amount of the waste that is originally planned. Accordingly, the detection limit is required to be as low as the clearance level for the very low level radioactive waste planned to be disposed of trench-type. In this report, the feasibility of the non-destructive assay method is studied by model calculations for gamma emitters. It is confirmed that the detection limit less than the clearance level can be achieved as regards the box type metal container that is difficult to measure. This report summarizes the requirements for the non-destructive measuring equipment.
Nakata, Hisakazu; Takao, Hajime*; Chijimatsu, Masakazu*; Noma, Yasutaka*; Amazawa, Hiroya; Sakai, Akihiro
JAEA-Technology 2018-014, 43 Pages, 2019/03
JAEA-Technology-2018-014.pdf:5.91MB
Japan Atomic Energy Agency plans to install disposal facilities for radioactive waste arising from research institutes. One relevant technical standard by the safety regulation is that the disposal facility shall be performance so as not to be left with harmful voids after backfilling with soil. Additionally no harmful void needs to exist in the waste packed in metal containers. The harmful void is supposed to result in the collapse of the disposal facility after structural materials of the container deteriorate and then become a state that can not retain the structure on its own. That leads to have an adverse impact on the facility such that the shape of cover soil deforms the way in which stagnant water is likely to occure. For which reason, a waste acceptance criteria relating to the quantity of voidage in a waste package needs to be defined quantitatively, which is preliminary less than 20% in a volum ratio based on this study.
Nakata, Hisakazu; Amazawa, Hiroya; Izumo, Sari; Okada, Shota; Sakai, Akihiro
Dekomisshoningu Giho, (58), p.10 - 23, 2018/09
Low level radioactive wastes are generated in the research and development of the nuclear energy, medical and industrial use of radioisotope except NPP in Japan. The disposal of wastes arising from NPP has already been implemented while not the one for wastes from research institutes etc. Japan Atomic Energy Agency therefore has been assigned an implementing organization for the disposal legally in 2008 in order to promote the disposal program as quickly and firmly as possible. Since then, JAEA has conducted their activity relating to the disposal facility design on generic site conditions and developing Waste Acceptance Criteria for LLW from research institutes. This report summarizes the WAC and current challenges.
Sakamoto, Yoshiaki
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 24(2), p.141 - 146, 2017/12
Some research reactors are under decommissioning or preparation for application of decommissioning license for regulation authority in our country. The reasonable treatment and disposal of dismantling waste is important for decommissioning of research reactors. Therefore, in this paper, JAEA's approach of the treatment and disposal of dismantling waste was introduced from the point of view of disposal of low level radioactive waste arising from research, industrial and medical facilities.
Waste Technical Standards Working Group
JAEA-Review 2017-017, 112 Pages, 2017/11
JAEA-Review-2017-017.pdf:2.87MB
In Japan Atomic Energy Agency, JAEA, a Waste Technical Standards Working Group has established since FY2015. The Working Group is composed of the members from waste management sections in each site in JAEA and from Radioactive Waste Management and Disposal Project Department. In this Working Group, we discussed quality management on conditioning waste packages, methodologies to evaluate the radioactivity concentration and measures for dismantling waste. This annual report summarizes the results of discussion in FY2016.
Waste Technical Standards Working Group
JAEA-Review 2016-020, 61 Pages, 2016/09
JAEA-Review-2016-020.pdf:1.55MB
Radioactive Waste Management and Disposal Project Department has set up a Working Group for the purpose of sharing information within the Sector of Decommissioning and Radioactive Wastes Management of Japan Atomic Energy Agency, heading towards implementation of disposal of low level radioactive waste generated from research, medical and industrial facilities. Waste package quantities and its radioactivity inventory which are needed for disposal project planning and facility design, as well as methods for corresponding to the technical standards on confirmation related to waste disposal, radioactivity evaluation techniques and quality control methods have been addressed in the Working Group. This annual report summarizes the activities of the Working Group in the FY 2015 regarding quality management system related to the manufacturing of the waste packages, standard manual for radioactivity data acquisition of JAEA and future issues on the basis of the results by 2014.
Hagiwara, Shigeru*; Sakamoto, Yoshiaki*; Takebe, Shinichi; Nakayama, Shinichi
JAERI-Data/Code 2004-004, 167 Pages, 2004/03
JAERI-Data-Code-2004-004.pdf:10.14MB
no abstracts in English
Hagiwara, Shigeru*; Sakamoto, Yoshiaki*; Takebe, Shinichi; Nakayama, Shinichi
JAERI-Data/Code 2004-003, 159 Pages, 2004/03
JAERI-Data-Code-2004-003.pdf:10.26MB
no abstracts in English
Sakai, Akihiro; Okoshi, Minoru
Radiation Risk Assessment Workshop Proceedings, p.175 - 186, 2003/00
To establish the clearance levels, the Nuclear Safety Commission (NSC) has been discussing the clearance levels since May 1997. The NSC derived the unconditional clearance levels for the solid materials, namely concrete and metal, arising from the operation and dismantling of nuclear reactors and post irradiation examination (PIE) facilities. Two destinations of the cleared materials, namely disposal and recycle/reuse, were considered. Deterministic calculation models were established to assess individual doses resulting from 73 exposure pathways, and realistic parameter values were selected considering the Japanese natural and social conditions. The clearance levels for 21 radionuclides of nuclear reactors and for 49 of PIE facilities were derived as radioactivity concentration equivalent to the individual doses of 10 
Sv/y. Most of calculated clearance levels were nearly the same as those shown in IAEA-TECDOC-855. Some, however, were different. It is considered that the major reasons depend on differences of fixed scenarios and of selected values of parameters.
Okoshi, Minoru; Sakai, Akihiro; Abe, Masayoshi; Tanaka, Mitsugu
IAEA-CN-87/50 (CD-ROM), p.113 - 118, 2002/12
As the result of research activities for nuclear energy utilization over 45 years, large amounts of low-level radioactive waste (LLW) are stored at Tokai Research Establishment of JAERI. In order to plan the disposal program, JAERI carried out the radiological characterization of the waste. The results show that about 34,400 tons of LLW will arise from the operation and dismantling of the facilities by the end of 2045. The total activities of beta- and gamma-radionuclides and alpha-radionuclides are about 44 PBq and 56 TBq, respectively. By using the estimated total weight and radioactivities of the waste, important radionuclides were selected from the viewpoint of safety according to the performance assessment of near surface disposal facilities. As the results, twenty-seven radionuclides including twelve alpha-ray emitting actinides were selected as the candidate important radionuclides. Those are slightly different from important radionuclides selected for commercial nuclear power plants because of materials used for facilities and so on.
Okoshi, Minoru
KURRI-KR-56, p.39 - 57, 2001/03
no abstracts in English
Okoshi, Minoru; Sakai, Akihiro; Yoshimori, Michiro; Yamamoto, Hideaki; Takahashi, Tomoyuki; Kimura, Hideo
Proc. of 7th Int. Conf. on Radioactive Waste Management and Environmental Remediation (ICEM'99)(CD-ROM), 8 Pages, 1999/09
no abstracts in English
Okoshi, Minoru
Kemikaru Enjiniyaringu, 44(2), p.60 - 64, 1999/02
no abstracts in English
Okoshi, Minoru; Takahashi, Tomoyuki*; Kimura, Hideo; ; Sakai, Akihiro; Yoshimori, Michiro; Yamamoto, Hideaki
Hoken Butsuri, 34(2), p.187 - 197, 1999/00
no abstracts in English
Tanaka, Mitsugu; Okoshi, Minoru
Proceedings of Joint NEA/IAEA/EC Workshop on the Regulatory Aspects of Decommissioning, 3A, p.141 - 146, 1999/00
no abstracts in English
Okoshi, Minoru
JAERI-Review 97-009, 32 Pages, 1997/08
JAERI-Review-97-009.pdf:1.24MB
no abstracts in English
Miyasaka, Yasuhiko
Dekomisshoningu Giho, 0(14), p.24 - 33, 1996/08
no abstracts in English
