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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

Technology development on reactor dismantling and investigation of contamination in FUGEN

Soejima, Goro; Iwai, Hiroki; Nakamura, Yasuyuki; Hayashi, Hirokazu; Kadowaki, Haruhiko; Mizui, Hiroyuki; Sano, Kazuya

Proceedings of 25th International Conference on Nuclear Engineering (ICONE-25) (CD-ROM), 5 Pages, 2017/07

no abstracts in English

Journal Articles

Preliminary re-conditioning test of the bituminization for radioactive wastes

Soejima, Goro; Takiya, Hiroaki; Mizui, Hiroyuki; Fujita, Yoshihiko*; Akari, Eisaku*; Endo, Nobuyuki*; Kume, Kyo*

Heisei-27-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 18, P. 14, 2016/10

We have performed the preliminary re-conditioning test of the bituminization for radioactive wastes applying to the technical criteria by non-radioactive samples. As a result, we have confirmed the applicability to secure homogeneity that is a part of the technical criteria by evaluating sample properties.

JAEA Reports

The Development of the basic dismantling procedure of the reactor of FUGEN

Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-046, 110 Pages, 2016/03

JAEA-Technology-2015-046.pdf:85.22MB

Advanced Thermal Reactor (ATR) FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube-type reactor with the thermal power of 557 MW and the electrical power of 165 MW. The reactor of FUGEN is classified into the core region and the shielding region. The core region is highly activated owing to the long term operation, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel closely. And the shielding region surrounding the core region has the laminated structure composed of up to 150 mm thickness of carbon steel. The reactor is planning to be dismantled under water remotely in order to shield the radiation around the core and prevent airborne dust generated by the cutting, and firing of zirconium material. This paper reports on the result of development of the basic dismantling procedure of the reactor of FUGEN.

JAEA Reports

The Selection of the cutting technologies for dismantling the FUGEN reactor

Nakamura, Yasuyuki; Iwai, Hiroki; Mizui, Hiroyuki; Sano, Kazuya

JAEA-Technology 2015-045, 137 Pages, 2016/03

JAEA-Technology-2015-045.pdf:27.77MB

FUGEN is 9 m outer-diameter and 7m height, and characterized by its tube-cluster construction that contains 224 fuel channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure composed of up to 150 mm thickness of carbon steel for radiation shielding. The structure of the reactor, which is made of various materials such as stainless steel, carbon steel, zirconium alloy and aluminum. The reactor is planning to be dismantled under water in order to shield the radiation ray around the core and prevent airborne dust generated by the cutting, the temporary pool structure and the remote-operated dismantling machines needs to be installed on the top of reactor. In consideration of above the structure of Fugen reactor, the cutting method was selected for dismantling the reactor core in order to shorten the dismantling term and reduce the secondary waste.

Journal Articles

The Study on application of laser technology for the reactor core dismantling

Iwai, Hiroki; Nakamura, Yasuyuki; Mizui, Hiroyuki; Sano, Kazuya; Morishita, Yoshitsugu

Proceedings of 7th International Congress on Laser Advanced Materials Processing (LAMP 2015) (Internet), 4 Pages, 2015/08

The reactor of FUGEN is characterized by its tube-cluster construction that contains 224 channels arranging both the pressure and the calandria tubes coaxially in each channel. And the periphery part of the core has the laminated structure of up to 150 mm thickness of carbon steel for radiation shielding. Method for dismantling the reactor core is also being studied with considering processes of dismantlement by remote-handling devices under the water for the radiation shielding. In order to shorten the term of the reactor dismantlement work and reduce the secondary waste, some cutting tests and literature research for various cutting methods had been carried out. As the result, the laser cutting method, which has feature of the narrow cutting kerf and the fast cutting velocity, was mainly selected for dismantling the reactor. In this presentation, current activities of FUGEN decommissioning and R&D of laser cutting tests are introduced.

Journal Articles

Application of measurement and evaluation method on the clearance system of the Fugen NPP for dismantled equipment of turbine system

Hayashi, Hirokazu; Soejima, Goro; Mizui, Hiroyuki; Sano, Kazuya

Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 7 Pages, 2015/05

In the Fugen Nuclear Power Plant, we are going to conduct appropriate classification of the waste according to the contamination level of the material of the plant, to reduce the amount of radioactive waste and to promote dismantling work rationally and efficiently. For this reason, we are going to apply the clearance system to the dismantled material generated from dismantling work of the turbine system, and to reduce the radioactive waste amount as much as possible. In order to operate the clearance system properly, the target nuclides need to be selected accurately, and the evaluation method of them should be established. The assessment was conducted as follows.

Journal Articles

Estimation of radioactive substance penetration in basement concrete

Mizui, Hiroyuki; Fujita, Yoshihiko*; Kume, Kyo*

Heisei-25-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 16, P. 67, 2014/10

no abstracts in English

Journal Articles

Analytical surveillance on production methods of homogeneous and uniform solid materials from spent ion exchange residuum after ion coupled plasma volume-reduction process

Otani, Hiroshi; Mizui, Hiroyuki; Higashiura, Norikazu; Bando, Fumio*; Endo, Nobuyuki*; Yamagishi, Ryuichiro*; Kume, Kyo*

Heisei-25-Nendo Koeki Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 16, P. 66, 2014/10

no abstracts in English

JAEA Reports

Document collection of the 28th Technical Special Committee on Fugen Decommissioning

Kutsuna, Hideki; Iwai, Hiroki; Mizui, Hiroyuki; Kadowaki, Haruhiko; Nakamura, Yasuyuki

JAEA-Review 2013-049, 49 Pages, 2014/02

JAEA-Review-2013-049.pdf:5.59MB

Fugen Decommissioning Engineering Center has been establishing "Technical special committee on Fugen decommissioning" which consists of the members well-informed, aiming to make good use of Fugen as a place for technological development which is opened inside and outside the country. This report compiles presentation materials "The Current Situation of Fugen Decommissioning", "The Current Status of the Cutting Test toward the Practical Use of Laser Cutting Technology and the Future Plan", "Study on Radioactive Substance Osmosis for Basis Concrete of Equipment", "Verification Tests of the Room-Temperature Vacuum Drying and the Evaluation Method of Residual Amount of Heavy Water in the Tritium Removal" and "Applicability Test of Thermal and Mechanical Cutting Technology for the Dismantlement of the Internal Core of Fukushima Daiichi NPS", presented in the 28th Technical special committee on Fugen decommissioning which was held on September 24, 2013.

Journal Articles

Estimation of radioactive substance osmosis in basement concrete

Mizui, Hiroyuki; Ito, Hideki*; Kume, Kyo*

Heisei-24-Nendo Zaidan Hojin Wakasawan Enerugi Kenkyu Senta kenkyu Nempo, 15, P. 88, 2013/10

Radioactive substance osmosis in basement concrete has been estimated, to contribute disposal as NR waste in Fugen decommissioning engineering center.

Journal Articles

Decommissioning program of FUGEN and current activities

Tezuka, Masashi; Mizui, Hiroyuki; Matsushima, Akira; Nakamura, Yasuyuki; Hayashi, Hirokazu; Sano, Kazuya; Nanko, Takashi; Morishita, Yoshitsugu

Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.2815 - 2821, 2009/09

FUGEN is a proto-type heavy water moderated, boiling light water cooled, pressure tube type reactor with 165MWe and has been shut downed on Mar. 2003. Following the approval of decommissioning program in 2008, stage of FUGEN was changed to the decommissioning of the facilities. The program consists of following four periods; (1) Spent fuel transportation, (2) Periphery facilities dismantlement, (3) Reactor dismantlement and (4) Building demolition. It is expected that the whole decommissioning will be completed until 2028. As a part of the work in the spent fuel transportation period, the main steam system and the feeder water system etc. are being dismantled in the turbine building. The remaining tritium in the heavy water system is also being removed for facilitating the dismantlement of the heavy water system. Moreover, method on dismantlement of the reactor core is being studied with considering the process under the water for the radiation shielding and the dust suppression.

Journal Articles

Decommissioning program for ATR-FUGEN nuclear power station

Sano, Kazuya; Kitamura, Koichi; Tezuka, Masashi; Mizui, Hiroyuki; Kiyota, Shiko; Morishita, Yoshitsugu

Proceedings of 16th Pacific Basin Nuclear Conference (PBNC-16) (CD-ROM), 6 Pages, 2008/10

The operation of Advanced Thermal Reactor Fugen was terminated on Mar. 29th, 2003. After the operation, the preparative works and R&D have been conducted strenuously for the planning of the rational and safe decommissioning. The decommissioning program for Fugen was planed, based on the results of above works and R&D, and was applied to the government as a first case under the revised nuclear reactor regulation law. As a result, the program was approved on Feb. 12th, 2008. In this paper, the decommissioning program for Fugen was outlined, which are the dismantling process consists of four periods; (1) Spent fuel transportation, (2) Periphery facilities dismantlement, (3) Reactor dismantlement and (4) Building demolition, the amount of radioactive waste, the safety assessment etc.

Oral presentation

Microstructural development of multi-pass TIG welded F82H steels under dual-ion irradiation

Ogiwara, Hiroyuki; Tanigawa, Hiroyasu; Mizui, Tomohiro*; Kishimoto, Hirotatsu*; Koyama, Akira*

no journal, , 

Reduced-activation ferritic/martensitic steels for first wall and blanket structural component applications in a fusion reactor required joining by welding, and effects of displacement damage and helium production on mechanical properties and microstructures are important to these applications. In the fabrication of blanket modules, the joints of a first wall/side walls will be applied to a multi-pass tungsten inert gas (TIG) welding. The objectives of this work are to clarify the helium effects on swelling behavior and the microstructural evolution in the region welded by a multi-pass TIG welding. F82H steels were irradiated at 470 $$^{circ}$$C up to high dose 20 dpa by using 6.4 MeV Fe$$^{3+}$$ and/or energy-degraded 1.0 MeV He$$^{+}$$. The damage rate is 3.0$$times$$10$$^{-4}$$ dpa/s, and the helium injection rate is 15$$times$$10$$^{-3}$$ appm He/s. Microstructure and Vickers hardness profiles across base metal, heat affected zone (HAZ) and fusion zone (FZ) were examined before irradiation experiments. The amount of hardness in FZ increased in increments of number in welding passes. The swelling resistance varied with the type considered due to the phase transformation that occur during the heating and cooling cycles of the fusion welding process. In dual-ion irradiated FZ, cavities were observed to a region from one pass to fourth passes and not fifth passes, and amount of swelling decreased in increments of number in welding passes. The tempered zone offered the largest amount of swelling across HAZ.

Oral presentation

Current status of the decommissioning of FUGEN

Mizui, Hiroyuki; Hamada, Nobuyuki

no journal, , 

no abstracts in English

Oral presentation

Trial manifacture the axial cutting tool for small pipe

Mizui, Hiroyuki

no journal, , 

The axial cutting tool for small pipe will be manufactured.

Oral presentation

Measurement procedure and evaluation on the clearance at FUGEN, 2; Study for evaluating nuclides to be applied to the clearance

Mizui, Hiroyuki; Hayashi, Hirokazu; Iwai, Hiroki; Imagawa, Yasuhiro; Nanko, Takashi; Sano, Kazuya

no journal, , 

It is the study for evaluating nuclides to be applied to the clearance at FUGEN. The evaluating nuclides was decided to the 10 important nuclides by radioactivity.

Oral presentation

Basic test for making Waste package for Spent resin disposal

Otani, Hiroshi; Higashiura, Norikazu; Mizui, Hiroyuki; Endo, Nobuyuki*; Katagiri, Genichi*; Oshio, Tadashi*; Ogawa, Hideo*

no journal, , 

no abstracts in English

Oral presentation

Basic test for making waste package for spent resin disposal, 1; Volume reduction and stabilization process by low pressure oxygen plasma process for spent resin

Mizui, Hiroyuki; Otani, Hiroshi; Higashiura, Norikazu; Onozaki, Kimihiro*; Katagiri, Genichi*; Endo, Nobuyuki*; Ogawa, Hideo*; Kaneda, Yoshihisa*

no journal, , 

The applicable prospect for spent resin disposal including inhibitor was acquired by basic test of using low pressure oxygen plasma method.

Oral presentation

Study on radioactive substance osmosis for basis concrete of equipment

Mizui, Hiroyuki; Ito, Hideki*; Kume, Kyo*; Ogawa, Hideo*; Kaneda, Yoshihisa*

no journal, , 

Radioactive substance osmosis for basis concrete of equipment was estimated, to treat and dispose in decommissioning project of Fugen Decommissioning Engineering Center (Fugen). In this study, the osmosis of Cobalt (non-radioactive) in liquid to concrete was observed by using PIXE method and others. And, the crack depth was measured by using UT method and others. As a result, it was confirmed that radioactive substance was osmosed to depth of crack, if Cobalt in liquid was touched with the crack of concrete, but the hydrophobic coatings of surface protect the liquid osmosis in short time. And, the relationship between crack depth and liquid osmosis was observed as nearly correlation. The continuous study at Fugen will establish the estimation method for area of osmosis contamination possibilities for basis concrete of equipment in the near future.

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