Decommissioning state of Plutonium Fuel Fabrication Facility; Dismantling the glove box W-9 and equipment interior, and a part of tunnel F1

Nagai, Yuya; Shuji, Yoshiyuki; Kawasaki, Takeshi; Aita, Takahiro; Kimura, Yasuhisa; Nemoto, Yasunori*; Onuma, Takeshi*; Tomiyama, Noboru*; Hirano, Koji*; Usui, Yasuhiro*; et al.

JAEA-Technology 2022-039, 117 Pages, 2023/06

JAEA-Technology-2022-039.pdf:11.96MB

Japan Atomic Energy Agency (JAEA) manages wide range of nuclear facilities. Many of these facilities are required to be performed adjustment with the aging and complement with the new regulatory standards and the earthquake resistant, since the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident. It is therefore desirable to promote decommissioning of facilities that have reached the end of their productive life in order to reduce risk and maintenance costs. However, the progress of facility decommissioning require large amount of money and radioactive waste storage space. In order to address these issues, JAEA has formulated a "The Medium/Long-Term Management Plan of JAEA Facilities" with three pillars: (1) consolidation and prioritization of facilities, (2) assurance of facility safety, and (3) back-end countermeasures. In this plan, Plutonium Fuel Fabrication Facility has been selected as primary decommissioned facility, and dismantling of equipment in the facilities have been underway. In this report, size reduction activities of the glove box W-9 and a part of tunnel F-1, which was connected to W-9, are presented, and the obtained findings are highlighted. The glovebox W-9 had oxidation & reduction furnace, and pellet crushing machine as equipment interior. The duration of activity took six years from February 2014 to February 2020, including suspended period of 4 years due to the enhanced authorization approval process

Research on factor analysis and technical process for achieving denuclearization; Denuclearization of South Africa

Tazaki, Makiko; Kimura, Takashi; Shimizu, Ryo; Tamai, Hiroshi; Nakatani, Takayoshi; Suda, Kazunori

JAEA-Review 2022-056, 54 Pages, 2023/01

JAEA-Review-2022-056.pdf:1.86MB

As part of the "Research on Factor Analysis and Technical Processes for Achieving Denuclearization" South Africa's nuclear development and denuclearization cases were investigated then analyzed from seven denuclearization factors namely (1) motivation for nuclear development, (2) internal and external situations at the time of denuclearization decision, (3) progress of nuclear development, (4) effects of sanctions, (5) incentives for denuclearization, (6) international framework for denuclearization, (7) denuclearization and verification methods. At the same time, characteristics of its denuclearization and lessons learned from the denuclearization were also analyzed. South Africa shifted its nuclear activities from research and development of "peaceful nuclear detonation" in the 1970s to developing "limited nuclear deterrence" and finally to manufacturing "transportable nuclear weapons" in the late 1980s. By then, it had completed producing six nuclear explosive devices using highly enriched uranium. However, in 1989, along with the abolition of the apartheid policy, South Africa decided denuclearization and dismantled its nuclear explosive devices and related facilities. Upon completion of dismantlement, it joined the Treaty on the Non- Proliferation of Nuclear Weapons and concluded a Comprehensive Safeguards Agreement (CSA) with the International Atomic Energy Agency (IAEA). The South Africa has remained one of the rare countries that has continued to the peaceful use nuclear energy, and its voluntary denuclearization is considered as a good example of denuclearization in the future.

Consideration of a quick exit from plastic tents in an event of emergency while working with air-fed suits: Evaluation of applicability of plastic enclosure tents for body decontamination

Asakawa, Jun; Hirano, Hiroshi*; Nagai, Yuya; Aita, Takahiro; Shibanuma, Tomohiro; Kimura, Yasuhisa

Hoken Butsuri (Internet), 57(2), p.93 - 101, 2022/09

https://doi.org/10.5453/jhps.57.93

In the dismantling work of glove boxes (GBs) contaminated with radioactive materials at the nuclear fuel facilities, plastic tents are constructed around the entire GBs, and workers putting on air-fed suits (AFS) (hereinafter referred to as AFS worker) dismantle the GBs and interior equipment by using cutting tools. If an AFS worker suddenly feels sick during the work and the worker is unable to move independently, it will be necessary to exit in the shortest time from the viewpoint of respecting human life. In this case, a lot of radioactive materials may be brought into the contamination control room, thus the room and the equipment of the workers may be contaminated. Consequently, until the decontamination work is completed, the other AFS workers will have to put on AFS and wait for long time, which puts a strain on the workers. In this report, the plastic enclosure tents for body decontamination developed in JAEA were used as a new contamination control room replaced the contaminated one, and the procedure to quickly exit the remaining AFS workers was proposed. As a result, we confirmed that it was possible to greatly reduce the waiting time of the other AFS workers who is forced to wait in the dismantling area.

Research on factor analysis and technical process for achieving denuclearisation; Investigation on Libya's case

Tamai, Hiroshi; Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Nakatani, Takayoshi; Suda, Kazunori

JAEA-Review 2021-073, 19 Pages, 2022/03

JAEA-Review-2021-073.pdf:1.51MB

As a part of "Research on Factor Analysis and Technical Process for Achieving Denuclearisation", investigation on Libya's cases of nuclear development and denuclearisation, and analysis of its characteristics have been conducted. Libya had been suspected that dictator Qadaffi had an interest in the acquisition of weapons of mass destruction (WMD) since early 1970s after his revolution. US and UK intelligence were focusing on Libya's situation; however, actual status was not revealed for a long time. In 1980s, Libya faced to economic exhaustion due to sanctions from the international community against Libya's supporting terrorism. Libya decided to abandon WMD development and its denuclearisation in early 2000s. Several factors to prompt Libya's decisions can be highlighted; economic sanctions; witnessing regime collapse of President Hussein due to Iraq War who aimed at WMD; revealing secret procurement of centrifuge equipment through the inspection of German-flagged ships by US. Libya's denuclearisation was rapidly implemented to prevent Libya from reverting to nuclear development through well-coordinated roles among main players, quick decisions by Libyan side, and warning effect of Iraqi case. International Atomic Energy Agency (IAEA) played a central role in the verification of all related facilities and activities in Libya. Through safeguards activities beyond those permitted by Additional Protocol (AP), IAEA evaluated the whole Libya's nuclear programme. The denuclearisation was successfully completed by removal of nuclear materials and related equipment from Libya. It was also revealed that Libya's technological capabilities had not well developed to utilize procured materials and equipment. Libya's case is regarded in the international community as a good practice of denuclearisation. On the other hand, Qadaffi administration was overthrown by the democratisation movement that occurred after denuclearisation. It might be understood as a miserable end

Research on factor analysis for achieving denuclearization, 10; Summary of research; Analysis of denuclearization factors of target countries and lessons learned from the analysis

Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Nakatani, Takayoshi; Tamai, Hiroshi; Suda, Kazunori

Dai-42-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2021/11

no abstracts in English

Design and production of the valve used in Radioactive Liquid Disposal Facility

Nishimura, Arashi; Okada, Yuji; Sugaya, Naoto; Sonobe, Hiroshi; Kimura, Nobuaki; Kimura, Akihiro; Hanawa, Yoshio; Nemoto, Hiroyoshi

JAEA-Technology 2021-003, 51 Pages, 2021/05

JAEA-Technology-2021-003.pdf:5.55MB

In the Japan Materials Testing Reactor (JMTR), the leakage accidents of radioactive waste liquid were occurred from the tanks and pipes of the liquid waste disposal facility in the JMTR tank-yard building in JFY2014. In order to respond to the accident, obtain the approval of the JAEA to the design and construction method from JFY2016, the tanks and pipes were replaced from JFY2016 to 2019. In the replaced, the production of the tanks and pipes of the liquid waste disposal facility applied Japanese technical standards correspondingly. On the other hand, the valve did not fall under the category of Japanese technical standards. The manufacturing specifications when replacing the valve were decided based on the including the selecting the standards of production and inspection for valves, Fluid properties, experience in JMTR. The production proceeded while carrying out the decided inspection. The valves that passed all the inspections were installed together with the tanks and pipes of the liquid waste, and the finished inspection was performed as a systems. The construction was completed with those inspection passed. This report is summarized valve Design, production and installation.

Research on factor analysis for achieving denuclearization, 9; DPRK's denuclearization

Shimizu, Ryo; Kimura, Takashi; Tazaki, Makiko; Nakatani, Takayoshi; Tamai, Hiroshi; Suda, Kazunori

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 3 Pages, 2020/11

Efforts to denuclearize North Korea have been made by neighboring countries and related countries, but they have not abandoned North Korea's nuclear development. In this report, we will analyze the North Korean denuclearization negotiations that have been carried out so far, and report on the elements necessary for the realization of North Korea's denuclearization obtained from the past history.

Research on factor analysis for achieving denuclearization, 8; International frameworks for denuclearization and roles of the US, 1; Denuclearization of Iraq, Libya and Iran

Tazaki, Makiko; Shimizu, Ryo; Kimura, Takashi; Tamai, Hiroshi; Nakatani, Takayoshi; Suda, Kazunori

Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11

no abstracts in English

Validation of repairing method for concrete wall of the JMTR tank-yard building

Sugaya, Naoto; Okada, Yuji; Nishimura, Arashi; Sonobe, Hiroshi; Kimura, Nobuaki; Kimura, Akihiro; Hanawa, Yoshio; Nemoto, Hiroyoshi

JAEA-Testing 2020-004, 67 Pages, 2020/08

JAEA-Testing-2020-004.pdf:8.17MB

In the Japan Materials Testing Reactor (JMTR), the leakage accidents of radioactive waste liquid were occurred from the tanks and pipes of the liquid waste disposal facility in the JMTR tank-yard building in JFY2014. In order to respond to the accident, the tanks and pipes were replaced from JFY2016 to 2019. On the other hand, a lot of cracks were occurred on the concreate wall of the tank-yard building when the frame structure supports were fixed to the concrete wall in the replacement work. Thus, it is necessary to repair the concreate wall of the tank-yard building. Especially, some cracks with swelling (cone-shaped fracture) were raised around some anchor bolts (the post-installed chemical anchor bolts) fixed the frame structure supports. The repairing method for the cone-shaped fracture of the concrete wall is standardized, but there was no reference value of tensile strength for the validation of the post-installed chemical anchor bolts after the repairing method. In this report, the repairing method was selected for the cone-shaped fracture on the concreate wall and the reference value of tensile strength for the validation of the post-installed chemical anchor bolts by this repairing method. The mock-ups for repairing cone-shaped fracture were fabricated by the selected repairing method and the tensile tests of the post-installed chemical anchor bolts were performed. From the results, the validation of the repairing method was obtained in this test and it was obvious the repairing of cone-shaped fracture is preferable method for the concreate wall of the JMTR tank-yard building.

Synthesis report on the R&D for the Horonobe Underground Research Laboratory; Project carried out during fiscal years 2015-2019

Nakayama, Masashi; Saiga, Atsushi; Kimura, Shun; Mochizuki, Akihito; Aoyagi, Kazuhei; Ono, Hirokazu; Miyakawa, Kazuya; Takeda, Masaki; Hayano, Akira; Matsuoka, Toshiyuki; et al.

JAEA-Research 2019-013, 276 Pages, 2020/03

JAEA-Research-2019-013.pdf:18.72MB

The Horonobe Underground Research Laboratory (URL) Project is being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant disposal technologies for geological disposal of High-level Radioactive Waste through investigations of the deep geological environment within the host sedimentary rock at Horonobe Town in Hokkaido, north Japan. The investigations will be conducted in three phases, namely "Phase 1: Surface based investigations", "Phase 2: Construction phase" (investigations during construction of the underground facilities) and "Phase 3: Operation phase" (research in the underground facilities). According to the research plan described in the 3rd Mid- and Long- term Plan of JAEA, "Near-field performance study", "Demonstration of repository design option", and "Verification of crustal-movement buffering capacity of sedimentary rocks" are important issues of the Horonobe URL Project, and schedule of future research and backfill plans of the project will be decided by the end of 2019 Fiscal Year. The present report summarizes the research and development activities of these 3 important issues carried out during 3rd Medium to Long-term Research Phase.