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Yamashita, Kiyoto; Maki, Shota; Yokosuka, Kazuhiro; Fukui, Masahiro; Iemura, Keisuke
JAEA-Technology 2023-023, 97 Pages, 2024/03
JAEA-Technology-2023-023.pdf:8.21MB
The incinerator adopted to incineration room, Plutonium Waste Treatment Facility had been demonstrated since 2002 for developing technologies to reduce the volume of fire-resistant wastes such as vinyl chloride (represented by Polyvinyl chloride bags) and rubber gloves for Radio Isotope among radioactive solid wastes generated by the production of mixed oxide fuels. The incinerator, cooling tower, and processing pipes were replaced with a suspension period from 2018 to 2022, which fireproof materials on the inner wall of the incinerator was cracked and grown caused by hydrogen chloride generated when disposing of fire-resistant wastes. This facility consists of the waste feed process, the incineration process, the waste gas treatment process, and the ash removal process. We replaced the cooling tower in the waste gas treatment process from March 2020 to March 2021, and the incinerator in the incineration process from January 2021 to February 2022. In addition, samples were collected from the incinerator and the cooling tower during the removing and dismantling of the replaced devices, observed by Scanning Electron Microscope and X-ray microanalyzer, and analyzed by X-ray diffraction to investigate the corrosion and deterioration of them. This report describes the method of setting up the green house, the procedure for replacing them, and the results from analysis in corrosion and deterioration of the cooling tower and incinerator.
Nakayama, Masashi
JAEA-Review 2023-032, 159 Pages, 2024/02
JAEA-Review-2023-032.pdf:19.37MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2022, we continued R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rock to natural perturbations". These are identified as key R&D on challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. Specifically, "full-scale engineered barrier system (EBS) performance experiment" and "solute transport experiment with model testing" were carried out as part of "Study on near- field system performance in geological environment". "Demonstration of engineering feasibility of repository technology" and "evaluation of EBS behaviour over 100
C" were addressed for "Demonstration of repository design options". A study on "Understanding of buffering behaviour of sedimentary rock to natural perturbations" was also implemented in two areas, "evaluation of intrinsic buffering against endogenic and exogenic processes" and "development of techniques for evaluating excavation damaged zone (EDZ) self-sealing behaviour after backfilling". The Horonobe International Project (HIP) was initiated in February 2023 to promote research and development in collaboration with national and international organizations.
Collaborative Laboratories for Advanced Decommissioning Science; Ibaraki University*
JAEA-Review 2023-021, 112 Pages, 2024/02
JAEA-Review-2023-021.pdf:7.1MB
The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2020. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2018, this report summarizes the research results of the "Contribution to Risk Reduction in Decommissioning Works by the Elucidation of Basic Property of Radioactive Microparticles" conducted from FY2018 to FY2021 (this contract was extended to FY2021). The present study aims to understand the basic properties (size, chemical composition, isotopic composition - including concentration of 
-emitters, electrostatic properties, and optical properties, etc.) of fine particles composed of silicate with insoluble properties which contain regions of highly concentrated radioactive cesium (Cs) released to the environment by the accident at the Fukushima Daiichi Nuclear Power Station of TEPCO in 2011 March.
Kamada, Masaki*; Yoshida, Takuma*; Sugita, Tsukasa*; Okumura, Keisuke
Nihon Genshiryoku Gakkai-Shi ATOMO
, 66(2), p.83 - 86, 2024/02
no abstracts in English
Kawahara, Takahiro; Suda, Shoya; Fujikura, Toshiki; Masai, Seita; Omori, Kanako; Mori, Masakazu; Kurosawa, Tsuyoshi; Ishihara, Keisuke; Hoshi, Akiko; Yokobori, Tomohiko
JAEA-Technology 2023-020, 36 Pages, 2023/12
JAEA-Technology-2023-020.pdf:2.79MB
We have been storing drums containing radioactive waste (radioactive waste packages) at waste storage facilities. We have been managing radioactive waste packages along traditional safety regulations. However, over 40 years has passed from a part of them were brought in pit-type waste storage facility L. Most of them are carbon steel 200 L drums, and surface of them are corroded. For better safety management, we started to take drums out from the pit and inspect them in FY 2019. After each inspection, we repair them or remove the contents of the drum and refill new drums if necessary. In this report, we will introduce the planning, the review of the plan, and the trial operation of this project.
Nakayama, Masashi
JAEA-Review 2023-019, 70 Pages, 2023/11
JAEA-Review-2023-019.pdf:6.83MB
The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant technologies for geological disposal of high-level radioactive waste through investigating the deep geological environment within the host sedimentary rocks at Horonobe Town in Hokkaido, north Japan. In the fiscal year 2023, we continue R&D on "Study on near-field system performance in geological environment", "Demonstration of repository design options", and "Understanding of buffering behaviour of sedimentary rocks to natural perturbations". These are identified as key R&D challenges to be tackled in the Horonobe underground research plan for the fiscal year 2020 onwards. In the "Study on near-field system performance in geological environment", we conduct the coupled analysis on the full-scale engineered barrier system performance experiment and test the coupled simulation code through comparison with different simulation codes in the international DECOVALEX-2023 collaboration project. Borehole investigations are also carried out for solute transport experiments in the Koetoi Formation. As for "Demonstration of repository design concept", we carry out in situ experiments and data analysis on concrete deterioration under the subsurface conditions. Geophysical surveys are also carried out around an experimental tunnel to be newly excavated at the 350m gallery and characterise the initial conditions of the excavation damaged zone. For the "Understanding of buffering behaviour of sedimentary rocks to natural perturbations", we analyse the results of the hydraulic disturbance tests conducted in previous years and understand the relationship between rock stress / stress state and fault / fracture hydraulic connectivity. Concerning the construction and maintenance of the subsurface facilities, the 350 m gallery is extended and shafts are sank to a depth of 500 m.
Tobita, Minoru*; Goto, Katsunori*; Omori, Takeshi*; Osone, Osamu*; Haraga, Tomoko; Aono, Ryuji; Konda, Miki; Tsuchida, Daiki; Mitsukai, Akina; Ishimori, Kenichiro
JAEA-Data/Code 2023-011, 32 Pages, 2023/11
JAEA-Data-Code-2023-011.pdf:0.93MB
Radioactive wastes generated from nuclear research facilities in Japan Atomic Energy Agency are planning to be buried in the near surface disposal field as trench and pit. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes until the beginning of disposal. In order to contribute to the study of radioactivity concentration evaluation methods for radioactive wastes generated from nuclear research facilities, we collected and analyzed concrete samples generated from JRR-3, JRR-4 and JAERI Reprocessing Test Facility. In this report, we summarized the radioactivity concentrations of 23 radionuclides (
H, 
C, 
Cl, 
Ca, 
Co, 
Ni, 
Sr, 
Nb, 
Ag, 
Cs, 
Ba, 
Eu, 
Eu, 
Ho, 
U, 
U, 
U, Pu, 
Pu, 
Pu, 
Am, 
Am, 
Cm) which were obtained from radiochemical analysis of the samples in fiscal years 2021-2022.
Nagai, Haruyasu; Furuta, Yoshihiro*; Nakayama, Hiromasa; Satoh, Daiki
Journal of Nuclear Science and Technology, 60(11), p.1345 - 1360, 2023/11
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)A novel monitoring method for the quantitative visualization of 3D distribution of a radioactive plume and source term estimation of released radionuclides is proposed and its feasibility is demonstrated by preliminary test. The proposed method is the combination of gamma-ray imaging spectroscopy with the Electron Tracking Compton Camera (ETCC) and real-time high-resolution atmospheric dispersion simulation based on 3D wind observation with Doppler lidar. The 3D distribution of a specific radionuclide in a target radioactive plume is inversely reconstructed from line gamma-ray images from each radionuclide by several ETCCs located around the target by harmonizing with the air concentration distribution pattern of the plume predicted by real-time atmospheric dispersion simulation. A prototype of the analysis method was developed, showing a sufficient performance in several test cases using hypothetical data generated by numerical simulations of atmospheric dispersion and radiation transport.
Furutaka, Kazuyoshi; Ozu, Akira; Toh, Yosuke
Nuclear Engineering and Technology, 55(11), p.4002 - 4018, 2023/11
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Yokoyama, Miki*; Onuma, Susumu*; Osawa, Hideaki; Otomo, Shoji*; Hirose, Yukio*
Humanities & Social Sciences Communications (Internet), 10(1), p.623_1 - 623_10, 2023/09
This study demonstrates that a decision-making process utilising "the veil of ignorance" concept, defined in process terms as beginning from a blank slate encompassing the entire country as potential sites and shortlisting candidate sites based on scientific (geological) safety, promotes public acceptance of siting a repository for the geological disposal of high-level radioactive waste and fosters procedural fairness.
Minari, Eriko*; Kabasawa, Satsuki; Mihara, Morihiro; Makino, Hitoshi; Asano, Hidekazu*; Nakase, Masahiko*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 60(7), p.793 - 803, 2023/07
Times Cited Count：2 Percentile：53.91(Nuclear Science & Technology)Department of Decommissioning and Waste Management
JAEA-Review 2023-001, 136 Pages, 2023/06
JAEA-Review-2023-001.pdf:10.65MB
This report describes the activities of Department of Decommissioning and Waste Management (DDWM) in Nuclear Science Research Institute (NSRI) in the period from April 1, 2021 to March 31, 2022. The report covers organization and missions of DDWM, outline and operation/maintenance of facilities which belong to DDWM, treatment and management of radioactive wastes, decommissioning activities, and related research and development activities which were conducted in DDWM. In FY2021 radioactive wastes generated from R&D activities in NSRI were treated safely. They were about 206 m of combustible solid wastes and 155 m of noncombustible solid wastes and 113 m of liquid wastes. After adequate treatment, 760 waste packages (in 200 L-drum equivalent) were generated. The total amounts of accumulated waste packages were 126,827 as of the end of FY2021 due to efforts of the restitution of waste packages to the Japan Radioisotope Association and volume reduction treatments of the stored waste packages. Decommissioning activities were carried out for the JAEA's Reprocessing Test Facility (JRTF), the Liquid Waste Treatment Facilities, the Compaction Facilities, and Fusion Neutronics Source (FNS) facilities. As for the R&D activities, studies on radiochemical analyses of wastes for disposal were continued. In order to pass the conformity review on the New Regulatory Requirements for waste management facilities, the Approval of the design and construction method was applied sequentially for the Nuclear Regulation Authority. The ministry of the Environment and Tokai-mura office requested JAEA to dispose of the contaminated soil generated by the accident of the Fukushima Daiichi Nuclear Power Station. The monitoring work at the playground was conducted during this period.
Sawaguchi, Takuma; Takai, Shizuka; Sasagawa, Tsuyoshi; Uchikoshi, Emiko*; Shima, Yosuke*; Takeda, Seiji
MRS Advances (Internet), 8(6), p.243 - 249, 2023/06
In the intermediate depth disposal of relatively high-level radioactive waste, a method to confirm whether the borehole for monitoring is properly sealed should be developed in advance. In this study, groundwater flow analyses were performed for the hydrogeological structures with backfilled boreholes, assuming sedimentary rock area, to understand what backfill design conditions could prevent significant water pathways in the borehole, and to identify the confirmation points of borehole sealing. The results indicated the conditions to prevent water pathways in the borehole and BDZ (Borehole Disturbed Zone), such as designing the permeability of bentonite material less than or equal to that of the host rock, and grouting BDZ.
Yoshida, Kazuo; Tamaki, Hitoshi; Hiyama, Mina*
JAEA-Research 2023-001, 26 Pages, 2023/05
JAEA-Research-2023-001.pdf:1.61MB
An accident of evaporation to dryness by boiling of high-level radioactive liquid waste (HLLW) is postulated as one of the severe accidents caused by the loss of cooling function at a fuel reprocessing plant. In this case, volatile radioactive materials, such as ruthenium (Ru) are released from the tanks with water and nitric-acid mixed vapor into the atmosphere. Accurate quantitative estimation of released Ru is one of the important issues for risk assessment of those facilities. To resolve this issue, an analytical approach has been developed using computer simulation programs to assess the radioactive source term from those facilities. The proposed approach consists analyses with three computer programs. At first, the simulation of boiling behavior in the HLLW tank is conducted with SHAWED code. Next step, the thermal-hydraulic behavior in the facility building is simulated with MELCOR code based on the results at the first step simulation such as flowed out mixed steam flow rate, temperature and volatilized Ru from the tank. The final analysis step is carried out for estimating amount of released radioactive materials with SCHERN computer code which simulates chemical behaviors of nitric acid, nitrogen oxide and Ru based on the condition also simulated MELCOR. Series of sample simulations of the accident at a hypothetical typical facility are presented with the data transfer between those codes in this report.
Aono, Ryuji; Mitsukai, Akina; Tsuchida, Daiki; Konda, Miki; Haraga, Tomoko; Ishimori, Kenichiro; Kameo, Yutaka
JAEA-Data/Code 2023-002, 81 Pages, 2023/05
JAEA-Data-Code-2023-002.pdf:3.0MB
Radioactive wastes generated from nuclear research facilities in Japan Atomic Energy Agency are planning to be buried in the near surface disposal field as trench and pit. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes until the beginning of disposal. In order to contribute to this work, we collected and analyzed the samples generated from JRR-2, JRR-3 and Hot laboratory facilities. In this report, we summarized the radioactivity concentrations of 20 radionuclides (H, C, Cl, Co, Ni, Sr, Nb, 
Tc, Ag, 
I, Cs, Eu, Eu, U, U, Pu, Pu, Pu, Am, Cm) which were obtained from radiochemical analysis of the samples in fiscal year 2020.
Sakai, Akihiro
Dekomisshoningu Giho, (64), p.24 - 33, 2023/05
Japan Atomic Energy Agency (JAEA) has proceeded with the project of near surface disposal of radioactive waste generated from research facilities, etc. as the implementing body. On the other hand, Nuclear Regulation Authority (NRA) has established the safety regulations and standards for the operation of the disposal facilities. This report outlines the disposal project of JAEA and the development of the regulations and standards for the disposal by NRA.
Yoshida, Yukihiko
IL Nuovo Cimento, 46(2), p.33_1 - 33_8, 2023/03
Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi
JAEA-Technology 2022-029, 55 Pages, 2023/02
JAEA-Technology-2022-029.pdf:2.77MB
Japan Materials Testing Reactor (JMTR) was decided as a one of decommission facilities in April 2017. The activation activity of secondary radioactive contamination remaining in the reactor facility was evaluated in order to submit the decommissioning plan to the Nuclear Regulation Authority. Total activation activity was 2.73
10
Bq after 12 years, 1.4610Bq after 21 years, respectively. The system with high activation activity was the primary cooling system in JMTR. The relatively large radionuclide was H-3, Fe-55, Co-60, Ni-63, Sr-90 and Cs-137. The radioactivity level was classified based on the values of the obtained radioactivity concentration. As a result, the primary cooling system and the drain system was classified as L2, and others was classified as L3. The nuclide that affected classification result was only Co-60 in irradiation facility of HR-1 and OSF-1. H-3, Co-60, Sr-90, Cs-137 and so on were affected classification in other system. When treating and disposing of radioactive waste, evaluation will be carried out based on appropriate methods.
Machida, Masahiko; Shi, W.*; Yamada, Susumu; Miyamura, Hiroko; Yoshida, Toru*; Hasegawa, Yukihiro*; Okamoto, Koji; Aoki, Yuto; Ito, Rintaro; Yamaguchi, Takashi; et al.
Proceedings of Waste Management Symposia 2023 (WM2023) (Internet), 11 Pages, 2023/02
Arai, Yoichi; Hasegawa, Kenta; Watanabe, So; Watanabe, Masayuki; Minowa, Kazuki*; Matsuura, Haruaki*; Hagura, Naoto*; Katsuki, Kenta*; Arai, Tsuyoshi*; Konishi, Yasuhiro*
Journal of Radioanalytical and Nuclear Chemistry, 9 Pages, 2023/00
Times Cited Count：0 Percentile：0.01(Chemistry, Analytical)