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Aratani, Kenta; Takiya, Hiroaki; Koda, Yuya; Ishiyama, Masahiro; Tezuka, Masashi; Mizui, Hiroyuki
Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 5 Pages, 2019/05
The prototype advanced thermal reactor FUGEN is the heavy water-moderated, boiling light water-cooled, pressure tube-type reactor, and has progressing the decommissioning since 2008. The most of facilities such as turbine system have the system structure and the operating conditions similar to those of BWR, although FUGEN has the characteristic structure of reactor core and the heavy water treatment facilities. In Japan, the knowledge and findings from FUGEN decommissioning activities are very important and valuable to perform BWR decommissioning in future, because the decommissioning of FUGEN is research and development as the first decommissioning of real-scale reactor. In the first phase of FUGEN decommissioning activities, the dismantlement project of reactor core cooling system started. By 2017, the low-level contaminated equipment such as the condensers of turbine system and the main-steam pipes of main-steam system was dismantled, and the management data was accumulated. The knowledge and findings from the 10 years of dismantlement experience will be reflected to the future dismantlement of higher contaminated facilities.
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.
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
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.
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.
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.
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.
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.
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
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
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.
Mizui, Hiroyuki; Ito, Hideki*; Kume, Kyo*
Heisei-24-Nendo Koeki 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.
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.
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.
山本 耕輔; 川越 慎司; 東浦 則和; 水井 宏之
not registered
JP, 2020-055379 Patent licensing information Patent publication (In Japanese)
【課題】評価の保守性の観点から放射能濃度を適切に評価することができる放射能評価方法を提供する。 【解決手段】放射能評価方法は、測定対象物の放射能濃度を算定する放射能濃度算定工程(S4)と、放射能濃度の相対誤差σ'Dを算定する誤差算定工程(S5)と、放射能濃度の相対誤差σ'Dに基づく不確定性を考慮して放射能濃度を評価する評価工程(S6)とを含み、誤差算定工程(S5)は、グロス計数率の測定プロセスに起因する複数のグロス誤差を重畳してグロス計数率の誤差σCGを算定するグロス誤差算定工程(S51)と、測定BG計数率の測定プロセス及び推定BG計数率の推定プロセスに起因する複数のBG誤差を重畳して推定BG計数率の誤差σCBGを算定するBG誤差算定工程(S52)と、グロス計数率の誤差σCGと、推定BG計数率の誤差σCBGとに基づいて、正味計数率の相対誤差σ'CNを算定する正味計数率誤差工程(S53)とを含む。
水井 宏之; 林 宏一; 副島 吾郎; 岩井 紘基; 山本 耕輔
not registered
JP, 2020-042714 Patent licensing information Patent publication (In Japanese)
【課題】冷却材に含まれるCP核種及びFP核種の放射能濃度を適切に評価することができる放射能評価方法を提供する。 【解決手段】冷却材Wに含まれる核種Xの放射能濃度DXを評価する放射能評価方法は、冷却系構造材起因の核種Xの第1の放射能濃度D1Xを評価する第1の評価工程(S1)と、第1の放射能濃度とFP核種補正項とに基づいて、核燃料物質起因の核種の第2の放射能濃度D2Xを評価する第2の評価工程(S2)と、第1の放射能濃度D1Xと第2の放射能濃度D2Xとに基づいて、核種Xの放射能濃度DXを評価する第3の評価工程(S3)とを含む。第2の評価工程では、冷却材濃度測定データと所定の汎用放射化解析コードによる放射能濃度とを用いてFP核種補正係数を算定し、冷却系構造材起因の核種の放射能濃度と冷却系構造材が含有する核燃料物質起因の核種の放射能濃度とを用いてFP寄与割合を算出し、FP核種補正項を算定する。
林 宏一; 水井 宏之; 副島 吾郎; 岩井 紘基
not registered
JP, 2020-060021 Patent licensing information Patent publication (In Japanese)
【課題】原子炉等の廃止措置において扱われる廃棄物に対するクリアランス判定に際して、評価の対象とすべき核種を、安全性を確保しつつ簡易に選定する。 【解決手段】全ての核種についてDKが算出される(S1)。次に、全てのDKに基づいてQ0が、重要核種(10種)のDKのみに基づいてQ1が選定のための指標値としてそれぞれ算出される(S2:算出工程)。Q1/Q0≧0.9でない場合(S3:NO)には、重要核種(10種)以外の核種の寄与が無視できないと認識されるため、重要核種以外で、DK/CKが大きな核種をDK/CKの大きな順に選定し、ここで追加された核種が、重要核種(10種)に加えて選定される(S7:選定工程)。DKの算出に際して、重要核種(10種類)に対しては下限側代表値が、重要核種以外の核種(23種類)に対しては上限側代表値)が、各元素の組成の代表値として用いられる。
山本 耕輔; 川越 慎司; 東浦 則和; 水井 宏之
not registered
JP, 2020-057662 Patent licensing information Patent publication (In Japanese)
【課題】評価の保守性の観点から放射能特性を適切に評価することができる放射能評価方法を提供する。 【解決手段】放射能評価方法は、グロス計数率CGが測定される前の第1のBG計数率CBG1と、グロス計数率CGが測定された後の第2のBG計数率CBG2との差分であるBG計数率変動量ΔCBGを算定するBG変動量算定工程(S4)と、第1のBG計数率CBG1及び第2のBG計数率CBG2の測定に含まれる複数の誤差要因に起因する複数のBG誤差を重畳することによりBG計数率変動量ΔCBGの誤差σΔCBGを算定するBG変動誤差算定工程(S5)と、BG計数率変動量ΔCBGの誤差σΔCBGに基づいて、BG計数率変動量ΔCBGとして許容されるBG計数率許容変動量ΔCBGLを算定し、当該BG計数率許容変動量ΔCBGLを用いてBG計数率変動量ΔCBGを評価して、測定作業の有効性を判定する有効性判定工程(S6)とを含む。
Mizui, Hiroyuki
no journal, ,
The axial cutting tool for small pipe will be manufactured.
Hayashi, Hirokazu; Soejima, Goro; Mizui, Hiroyuki; Sano, Kazuya
no journal, ,
no abstracts in English
