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Journal Articles

Status of decommissioning of FUGEN Decommissioning Engineering Center

Takiya, Hiroaki; Aratani, Kenta; Awatani, Yuto; Ishiyama, Masahiro; Tezuka, Masashi; Mizui, Hiroyuki

Dekomisshoningu Giho, (59), p.2 - 12, 2019/03

FUGEN Decommissioning Engineering Center received the approval of the decommissioning program in 2008, and we have been progressing the decommissioning. The first phase of decommissioning (Heavy Water and Other system Decontamination Period) finished in May 2018, and FUGEN has entered into the second phase of decommissioning (Reactor Periphery Facilities Dismantling Period). This report outlines the results obtained in the first phase of decommissioning of FUGEN.

Journal Articles

Development of waste acceptance criteria and current challenges relating to the disposal project of LLW generated in research, medical and industrial facilities

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.

Journal Articles

Establishment of Fukui Smart Decommissioning Technology Demonstration Base; Decommissioning Technology Demonstration Test Center (tentative name)

Muramatsu, Toshiharu; Sano, Kazuya; Terauchi, Makoto

Dekomisshoningu Giho, (57), p.65 - 74, 2018/03

The Decommissioning Technology Demonstration Test Center (tentative name) is established as a central facility of "Fukui Smart Decommissioning Technology Demonstration Base" which was adopted by the support policy "Regional Science and Technology Demonstration Base Establishment Project" of the Ministry of Education, Culture, Sports, Science and Technology in FY 2016 supplementary budget. This facility is a base to train local companies about technology concerning the decommissioning of nuclear power plants and for the industry, academia and government to contribute to the development of the regional economy and solving the problem of decommissioning under one roof, and consists of decommissioning dismantling technology verification field, laser processing advanced field and decommissioning mock-up test field. The papers introduce the outline of the facilities in each of these fields.

Journal Articles

Outline of decommissioning plan of Tokai Reprocessing Plant

Okano, Masanori; Akiyama, Kazuki; Taguchi, Katsuya; Nagasato, Yoshihiko; Omori, Eiichi

Dekomisshoningu Giho, (57), p.53 - 64, 2018/03

The construction of Tokai Reprocessing Plant (TRP) was initiated in June 1971, and its hot test using spent fuel started in September 1977. Thereafter TRP had been operated to reprocess 1,140 tons of spent fuel for approximately 30 years until May 2007, according to the reprocessing contract with domestic electric power companies. JAEA announced a policy of TRP in report of JAEA reform plan published in September 2014. The policy shows that TRP will shift to a decommissioning stage by economic reasons. Based on the policy, application of approval for TRP decommissioning plan was submitted to Nuclear Regulation Authority (NRA) in June 2017. This plan provides basic guidelines such as procedures for decommissioning and specific activities for risk reduction, and implementation divisions of decommissioning, management of spent fuels and radioactive wastes, decommissioning budget, and decommissioning schedule. The process of TRP decommissioning is planned to continue for approximately 70 years until the release of controlled areas of approximately 30 facilities.

Journal Articles

Outline of Oarai Waste Reduction Treatment Facility and volume reduction processing

Sakauchi, Hitoshi; Kikuchi, Yuki; Imaizumi, Haruki; Fukui, Yasutaka

Dekomisshoningu Giho, (57), p.34 - 42, 2018/03

OWTF (Oarai Waste Reduction Treatment Facility) is constructed for volume reduction processing and stabilization treatment of radioactive solid waste, which generate from hot facilities in Oarai Research and Development Center of Japan Atomic Energy Agency, using in-can type high frequency induction heating by remote control. In this report, we describe the outline of OWTF under construction and treatment technologies, in which incinerating and melting.

Journal Articles

Current status and issues of sodium removal and disposal from LMFR in the framework of decommissioning

Nakai, Satoru

Dekomisshoningu Giho, (56), p.14 - 28, 2017/09

Prototype fast breeder reactor power plant Monju which is under construction was decided by the Japanese government not to operate but to be decommissioned safely and surely in December 2016. In the view point of decommissioning, one of the major difference from LWR is sodium as a coolant. In the overseas such as U.K., Germany, the United States, France, there is the precedent example of decommissioning and can be referred to it. In this report, the situation and problem of overseas example about removal and disposal of sodium.

Journal Articles

The Initiative towards construction of Knowledge Management System in FUGEN Decommissioning Engineering Center

Tezuka, Masashi; Taruta, Yasuyoshi; Koda, Yuya

Dekomisshoningu Giho, (56), p.46 - 54, 2017/09

Implementation of decommissioning needs much plant information in period of Design, construction and operation. In addition, it is essential for efficient dismantling works to advance the technologies, data, lessons and learns, experiences and documents by getting through the decommissioning process. On the other hands, as workers who operated or maintained the plant are aging and retiring, their empirical knowledge has been lost. For the purpose of safety and reasonability of further decommissioning activities, Knowledge Management System (KMS) has been producing in FUGEN which is now under decommissioning. KMS is an initiative of human resources development and to pass on expertise and knowledge to the younger generations. The system based on the prototype of FUGEN aims a high versatility system available for further decommissioning facilities.

Journal Articles

Development of technologies of cutting and decontamination employing high power fiber laser

Toyama, Shinichi; Minehara, Eisuke*

Dekomisshoningu Giho, (56), p.55 - 65, 2017/09

Development of the steel cutting technology which employs high power fiber laser for the industrial applicability of the laser technology has been carried out at The Wakasa Wan Energy Research Center (WERC). At present, the laser technologies for dismantling and decontamination are concurrently being developed to the application measure of nuclear dismantling for domestic nuclear power plants in the future. Dismantling of nuclear facilities is now under the development in the world. The necessity of the technology is increasing and the development is strongly expected. Beside the relative easiness to handle compared with other laser system, suppression of production of secondary radioactive waste and dose exposure can be realized by the dramatic improvement by excelled thermal density of fiber laser. This paper provides recent results from cutting technology for thick steels aiming disassembling nuclear pressure vessel, and decontamination machine technology which works under high radiation dose, explaining the results from cutting experiment of steels and the actual equipment and from the radiation resistance experiment for component devices.

Journal Articles

Towards decommissioning of Tokai Reprocessing Plant

Yamamoto, Tokuhiro

Dekomisshoningu Giho, (55), P. 1, 2017/03

This is a prefatory note for Journal of the RANDEC (No.55, 2017). In September 2014, it was announced that the Tokai Reprocessing Plant would be toward decommissioning. Some unique features exist on decommissioning in case of reprocessing plant; for example, all of inner surface of equipment are contaminated, their contamination levels are difficult to estimate and their contaminations are eventually associated with $$beta$$-$$gamma$$ and/or $$alpha$$ nuclides. There are also some challenges arising primarily from long-term projects beyond generations. In the meantime, prioritized works will be carried out such as preparing decommissioning plans and acquiring permission, steady treatment of radioactive waste generated during reprocessing operation and decontamination of facilities. However, in the long term, it will be very important to utilize this historical opportunity of actual reprocessing plant decommissioning, so as to establish decommission technology of the nuclear fuel cycle facilities and to improve reprocessing technology through accumulation of technical data based on destructive analysis. Many people's collaboration and participation will be sincerely welcomed.

Journal Articles

Development of simple and rapid analytical method for radioactive samples by capillary electrophoresis

Haraga, Tomoko; Sato, Yoshiyuki; Kameo, Yutaka; Saito, Shingo*

Dekomisshoningu Giho, (55), p.22 - 27, 2017/03

no abstracts in English

Journal Articles

Current status of uranium measurements and their related techniques at JAEA Ningyo-toge

Ishimori, Yuu; Yokoyama, Kaoru*; Hayakawa, Tomoya; Hata, Haruhi; Sakoda, Akihiro; Naganuma, Masaki

Dekomisshoningu Giho, (55), p.36 - 44, 2017/03

This paper gives an outline of the current status of uranium measurements and their related techniques at the Ningyo-toge Environmental Engineering Center of Japan Atomic Energy Agency. The JAWAS-N and the Q$$^2$$ system have been adopted to evaluate uranium contents in the wastes. About 10 g or more of uranium in a 200 $$ell$$ drum can be evaluated by these systems. The equivalent model developed to correct the evaluation results with Q$$^2$$ system is not available to less than dozens of grams of uranium in a 200 L drum. The paper illustrates the advantage of use of the improved equivalent model which evaluates uranium content from full energy peak of 1001 keV and its Compton spectrum in order to correct the inhomogeneous distribution of uranium in measuring objects. The use of model achieved the limit of uranium quantitative determination under one tenth of those of previous evaluation methods. To determine $$^{235}$$U, it was demonstrated that the shielding factor, $$X_{geometry}$$ for evaluation of 1001 keV $$gamma$$-ray is also possible to use for evaluation of 186 keV $$gamma$$-ray. The measurement systems adopting the model have been introduced to other nuclear operators in Japan. In addition, it is also examined to use for clearance. As a related technique, feasibility studies on machine learning algorithms have been performed to classify the waste drums depending on their $$gamma$$-ray spectrum.

Journal Articles

Solidification of radioactive wastes using Alkali-activated materials "Geopolymer"

Meguro, Yoshihiro; Sato, Junya

Dekomisshoningu Giho, (54), p.48 - 55, 2016/09

Various radioactive wastes, especially liquiform, pulverized or grained one, have to be immobilized in a disposal container, and methods such as cement solidification, bituminization, etc are so far examined and have been adopted. In recent years novel inorganic solidification materials have been developed. These are named Alkali-activated materials and so geopolymer. Mainly studies of geopolymer applying to radioactive wastes as a solidification material are under research and development stage, but the cases applied to solidification of the real radioactive waste increase a lot. In this report, we briefly explain about some research studies and practical examples of the geopolymer in the field of nuclear energy, particularly those of radioactive wastes generated in Fukushima Daiichi Nuclear Power Station.

Journal Articles

Naraha Remote Technology Development Center and robots for nuclear disaster

Kawatsuma, Shinji

Dekomisshoningu Giho, (54), p.24 - 33, 2016/09

It has passed more than five years than Tokyo Electric Power Company's Fukushima Daiichi NPPs accidents occurred by huge tsunamis caused by the earthquake in Pacific Ocean Coast of North East District on March 11, 2011. It is very hard for workers to enter and stay for long time to work for decommissioning, because the radiation dose rate in the reactor buildings is too high to extremely high caused by radioactive materials released. Then the Naraha Remote Development Center has been constructed and taken into full operation in April 2016, which center would accelerate the development of remote technologies conducting decommissioning on the behalf of workers. The center is developing robot simulator system and robot performance testing method which could support developing remote operating equipment and devices. Also the center is preparing and operating remote equipment and devices for nuclear emergency response.

Journal Articles

Status of decommissioning of the Plutonium Fuel Fabrication Facility and R&Ds of dismantling technologies for gloveboxes

Kimura, Yasuhisa; Hirano, Hiroshi; Watahiki, Masatoshi; Kuba, Meiji; Ishikawa, Shinichiro

Dekomisshoningu Giho, (52), p.45 - 54, 2015/09

The Plutonium Fuel Fabrication Facility (PFFF) of the Japan Atomic Energy Agency is now in its decommissioning phase. In the PFFF, terminated gloveboxes have been dismantled. Gloveboxes to be dismantled are surrounded by a plastic enclosure to prevent contamination from being spread into process room. Dismantling operations for gloveboxes are performed manually by workers, each wearing an air-feed suit. However, the mental and physical loads placed on workers wearing the air-feed suits are intensively high. Therefore, R&Ds on new dismantling technologies including utilization of heavy machines covered with plastic enclosure for anti-contamination have been started to reduce the potential risks associated with workers and decommissioning costs. In this paper, the status of decommissioning of the PFFF and the overview of developed dismantling technologies for $$alpha$$-tight gloveboxes are described.

Journal Articles

Summary of discussion on AESJ special committee; Study of ensuring safety for near-surface disposal of uranium-bearing waste

Iguchi, Tetsuo*; Hasegawa, Makoto; Takahashi, Kuniaki; Enokido, Yuji*

Dekomisshoningu Giho, (52), p.12 - 19, 2015/09

no abstracts in English

Journal Articles

Decommissioning activities in FUGEN

Kitamura, Koichi; Kutsuna, Hideki; Matsushima, Akira; Koda, Yuya; Iwai, Hiroki

Dekomisshoningu Giho, (51), p.2 - 10, 2015/04

Fugen Decommissioning Engineering Center (herein after called as "FUGEN") obtained the approval of the decommissioning program on February 2008. FUGEN has been carrying out decommissioning works based on its decommissioning program since then. Now is in initial stage, the dismantling works was launched in turbine system whose contamination was relatively low level and their various data have been accumulating. And the draining heavy water, tritium decontamination and transferring of heavy water were carried out safely and reasonably. The preparation for the clearance system and the research and development works for the reactor core dismantling have been progressed steadily as well. Meanwhile, FUGEN has affiliation with local industries and universities for collaboration research, and has exchanged the decommissioning information with domestic and overseas organizations continuously.

Journal Articles

Clearance of concrete debris generated from modification of JRR-3

Satoyama, Tomonori; Nanri, Tomohiro; Kishimoto, Katsumi

Dekomisshoningu Giho, (49), p.11 - 21, 2014/03

Japan Atomic Energy Agency at the Nuclear Science Research Institute (NSRI) planned to apply the clearance system to about 4,000 tons of slightly contaminated concrete debris with radionuclides, which was generated from the modification of the Japan Research Reactor No.3 (JRR-3). The modification work was conducted from 1985 to 1990 and the generated concrete debris has been stored as radioactive waste in interim storage facilities in the NSRI. In 2008, the authority approved procedures for measuring and evaluating the radioactivity concentration of stored concrete debris. Since 2009, NSRI have been measuring and evaluating the radioactivity concentration of concrete debris, using the approved procedures. By the end of 2013, the authority had confirmed the correctness of our measurement and evaluation results on about 3,000 tons of concrete debris. About 1,800 tons of those cleared concrete were recycled as backfilling material in depressed areas around buildings caused by the Great East Japan Earthquake, and as roadbed material of the parking lots in the NSRI.

Journal Articles

Disassembly of JT-60 tokamak device

Okano, Fuminori; Ikeda, Yoshitaka; Sakasai, Akira; Hanada, Masaya; JT-60 Team

Dekomisshoningu Giho, (48), p.10 - 23, 2013/09

The disassembly of JT-60 tokamak device and its peripheral equipments, where the total weight was about 6200 tons, started in 2009 and accomplished in October 2012. This disassembly was required process for JT-60SA project, which is the Satellite Tokamak project under Japan-EU international corroboration to modify the JT-60 to the superconducting tokamak. This work was the first experience of disassembling a large radioactive fusion device based on Radiation Hazard Prevention Act in Japan. The cutting was one of the main problems in this disassembly, such as to cut the wielded parts together with toroidal field coils, and to cut the vacuum vessel into two. After solving these problems, the disassembly completed without disaster and accident. This report presents the outline of disassembly of JT-60 tokamak device.

Journal Articles

Progress on the disposal project of LLW generated from research, industrial and medical facilities

Miyamoto, Yoichi

Dekomisshoningu Giho, (47), p.10 - 28, 2013/03

no abstracts in English

Journal Articles

Overview and issues to be solved on emergency response of robots to Fukushima NPP accidents

Kawatsuma, Shinji

Dekomisshoningu Giho, (46), p.14 - 26, 2012/09

Fukushima NPP accident was occurred according to the earthquake of East Japan on the Pacific Ocean, on March 11th, 2011. Nuclear Disaster Robots, developed after JCO criticality accident, had been discarded, or stored but not maintained, so that those robots could not been deployed immediately. After that, Unmanned heavy construction machines, PackBOTs, BROKKs, Quince and other robots have been deployed. Development of the remote equipments for decommissioning of the Fukushima Nuclear Power Plants and preparation of maintenance and employment of the remote equipments in case of nuclear urgent are advanced. This paper summarized robots' emergency response to Fukushima NPP accident and future subjects, in order for the development and preparation mentioned above.

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