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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
Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Uwaba, Tomoyuki; Kaito, Takeji; Onuma, Masato*
Nuclear Materials and Energy (Internet), 9, p.346 - 352, 2016/12
Times Cited Count：21 Percentile：88.83(Nuclear Science & Technology)Takamatsu, Kuniyoshi; Takegami, Hiroaki; Ito, Chikara; Suzuki, Keiichi*; Onuma, Hiroshi*; Hino, Ryutaro; Okumura, Tadahiko*
Annals of Nuclear Energy, 78, p.166 - 175, 2015/04
Times Cited Count：10 Percentile：64.63(Nuclear Science & Technology)In our study, we focused on a nondestructive inspection method by which cosmic-ray muons could be used to observe the internal reactor from outside the RPV and the CV. We conducted an observation test on the HTTR to evaluate the applicability of the method to the internal visualization of a reactor. We also analytically evaluated the resolution of existing muon telescopes to assess their suitability for the HTTR observation, and were able to detect the major structures of the HTTR based on the distribution of the surface densities calculated from the coincidences measured by the telescopes. Our findings suggested that existing muon telescopes could be used for muon observation of the internal reactor from outside the RPV and CV.
Takegami, Hiroaki; Takamatsu, Kuniyoshi; Ito, Chikara; Hino, Ryutaro; Suzuki, Keiichi*; Onuma, Hiroshi*; Okumura, Tadahiko*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 13(1), p.7 - 16, 2014/03
One of the important problems for controlling of the Fukushima Daiichi Nuclear Power Plant is removing of fuel debris. As this preparation, the nondestructive inspection method for grasping the position of fuel debris is required. Therefore, we focused on a nondestructive inspection method using cosmic-ray muons. In this study, the applicability of this method for internal visualization of reactor was confirmed by preliminary test of internal visualization of High Temperature Engineering Test Reactor (HTTR). By using cosmic-ray muons, major components in the HTTR, such as concrete wall and reactor core, can be observed from the outside of a containment vessel. From the results, it appears that the inspection method with muons is a candidate method for searching the fuel debris in a reactor. Based on the results, we also proposed some improvements of this system for inspection at the Fukushima Daiichi Nuclear Power Station.
Takegami, Hiroaki; Terada, Atsuhiko; Noguchi, Hiroki; Kamiji, Yu; Ono, Masato; Takamatsu, Kuniyoshi; Ito, Chikara; Hino, Ryutaro; Suzuki, Keiichi*; Onuma, Hiroshi*; et al.
JAEA-Research 2013-032, 25 Pages, 2013/12
JAEA-Research-2013-032.pdf:3.56MB
We focused on a non-destructive inspection method using cosmic-ray muons as a candidate method for observation of internal the reactor from the outside of a reactor building. In this study, the applicability of this method for the reactor investigation was confirmed by a preliminary examination with High Temperature Engineering Test Reactor (HTTR). From the results of this examination, it appears that high density structures, such as the core and concrete walls, were able to observe by using muon telescope with coincidence method from the outside of the pressure vessel. Furthermore, we proposed some improvements of this muon inspection system for on-site investigation at the Fukushima Daiichi NPS.
Suzuki, Keiichi*; Onuma, Hiroshi*; Takegami, Hiroaki; Takamatsu, Kuniyoshi; Hino, Ryutaro; Okumura, Tadahiko*
Shadan Hojin Butsuri Tansa Gakkai Dai-129-Kai (Heisei-25-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu, p.131 - 134, 2013/10
In the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the nuclear fuel had melted down due to loss of coolant and had already become debris. The debris would fall to the bottom of the CV. To remove the debris for future decommission is necessary; however the area and the size are unclear. On the other hand, cosmic ray muons are absorbed extremely in the debris because of the high density of uranium and plutonium. The inner structure of the nuclear reactor may be visualized with muons penetrating easily throught such the high-density material, as a non-contact or -destructive inspection. In this study, the muons through the HTTR were measured and visualizing the internal structure was attempted. As a result, high density areas were recognized at the same position as that of the reactor pressure vessel (RPV); therefore, the technical possibility with muons could be demonstrated. In the near future, new R&Ds will be promoted toward the practical use.
Takahashi, Kiyoshi; Hanawa, Hiroshi; Onuma, Yuichi; Hosokawa, Jinsaku; Kanno, Masaru
JAEA-Technology 2012-007, 31 Pages, 2012/03
JAEA-Technology-2012-007.pdf:4.76MB
The Japan Materials Testing Reactor (JMTR), achieving first criticality in March 1968, has been used in testing the durability and integrity of reactor fuels and components, basic nuclear research, the production of radioisotopes, and other purposes. The JMTR, however, stopped in August 2006 after its 165th operation cycle, and is currently under going partial renewal of reactor facilities and installation of new irradiation facilities, geared toward being restarted in 2012. Now, the installation of two new irradiation facilities under the LWR irradiation environment were finished until 2011FY. One is a power ramping test facility of high-burnup fuel. Another one is a material irradiation facility for IASCC research under the LWR irradiation environment. And another irradiation facility (Hydraulic rabbit irradiation facility) maintenance is carried out on 2011FY. This report is described the installed new irradiation facilities and established irradiation facility until 2011FY in JMTR.
Hasegawa, Shin; Chen, J.; Koshikawa, Hiroshi; Iwase, Hiroki*; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari; Iwase, Hiroki*
Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.238 - 239, 2011/06
Radiation-induced graft polymerization of sulfo-containing styrene derivatives into crystalline poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer, so-called "super-engineering plastics". Graft polymerization of the sulfo-containing styrene, ethyl 4-styrenesulfonate (E4S) into PEEK substrates with degrees of crystallinity (DC) of 11 - 26% gradually progressed, achieving a grafting degree of more than 50% after 72 hours, whereas graft polymerization of the substrates with DC above 26% did not proceed. When morphological change in these films were measured by SAXS, PEEK films with DC larger than 26% showed a new peak at d=14 nm, corresponding to lamella structure. Thus, the suppression of graft polymerization of PEEK films with DC above 26% was due to obstruct of monomer diffusion by the formation of the oriented lamella structure.
Onuma, Yuichi; Okada, Yuji; Hanawa, Hiroshi; Tsuchiya, Kunihiko; Kanno, Masaru
JAEA-Review 2010-047, 27 Pages, 2010/11
JAEA-Review-2010-047.pdf:3.0MB
The Japan Materials Testing Reactor (JMTR) has been refurbished to re-operate from 2011. As a part of the establishment of new irradiation facilities, technology development for the dismantling and removing of irradiation facilities such as OWL-1 (Oarai Water Loop No.1), OWL-2 (Oarai Water Loop No.2) and IASCC (Irradiation Assisted Stress Corrosion Cracking) facility installed in the JMTR loop cubicles has been performed. By using developed methods, techniques for the dismantling and removing of the irradiation facilities were established.
Onuma, Yuichi; Tomita, Kenji; Okada, Yuji; Hanawa, Hiroshi
JAEA-Technology 2009-034, 79 Pages, 2009/07
JAEA-Technology-2009-034.pdf:11.23MB
Toward the re-operation of Japan Materials Testing Reactor on 2011 F.Y., the construction of new material irradiation facility for the stress corrosion cracking research under the LWR irradiation environment had been planed, and the design study of water control unit for BWR and water chemical study which supply the LWR simulated water to the material irradiation capsule were carried out on 2007 F.Y. The design study of new material irradiation facility was examined including the reflection of the operation experience and the reuse of components on old material irradiation facility. These examination results were summarized in this report.
Ide, Hiroshi; Matsui, Yoshinori; Kawamata, Kazuo; Taguchi, Taketoshi; Kanazawa, Yoshiharu; Onuma, Yuichi; Watanabe, Hiroyuki; Inoue, Shuichi; Izumo, Hironobu; Ishida, Takuya; et al.
JAEA-Technology 2008-012, 36 Pages, 2008/03
JAEA-Technology-2008-012.pdf:10.09MB
It is known that Irradiation Assisted Stress Corrosion Cracking (IASCC) occurs when austenitic stainless steel components used for light water reactor (LWR) are irradiated for a long period. In order to evaluate the high aging of the nuclear power plant, the study of IASCC becomes the important problem. The specimens irradiated in the reactor were evaluated by post irradiation examination in the past study. For the appropriate evaluation of IASCC, It is necessary to test it under the simulated LWR conditions; temperature, water chemistry and irradiation conditions. In order to perform in-pile SCC test, saturated temperature capsule (SATCAP) was developed. There are crack growth test, crack propagation test and so on for in-pile SCC test. In this report, SATCAP for crack propagation test is reported.
Ide, Hiroshi; Matsui, Yoshinori; Kawamata, Kazuo; Taguchi, Taketoshi; Kanazawa, Yoshiharu; Onuma, Yuichi; Watanabe, Hiroyuki; Inoue, Shuichi; Izumo, Hironobu; Ishida, Takuya; et al.
JAEA-Technology 2008-011, 46 Pages, 2008/03
JAEA-Technology-2008-011.pdf:19.39MB
It is known that Irradiation Assisted Stress Corrosion Cracking (IASCC) occurs when austenitic stainless steel components used for light water reactor (LWR) are irradiated for a long period. In order to evaluate the high aging of the nuclear power plant, the study of IASCC becomes the important problem. The specimens irradiated in the reactor were evaluated by post irradiation examination in the past study. For the appropriate evaluation of IASCC, It is necessary to test it under the simulated LWR conditions; temperature, water chemistry and irradiation conditions. In order to perform in-pile SCC test, saturated temperature capsule (SATCAP) was developed. There are crack growth test, crack propagation test and so on for in-pile SCC test. In this report, SATCAP for crack growth test is reported.
Tsuchiya, Kunihiko; Kawamura, Hiroshi; Mishima, Yoshinao*; Yoshida, Naoaki*; Tanaka, Satoru*; Uchida, Munenori*; Ishida, Kiyohito*; Shibayama, Tamaki*; Munakata, Kenzo*; Sato, Yoshiyuki*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 83(3), p.207 - 214, 2007/03
no abstracts in English
Matsui, Yoshinori; Hanawa, Satoshi; Ide, Hiroshi; Tobita, Masahiro*; Hosokawa, Jinsaku; Onuma, Yuichi; Kawamata, Kazuo; Kanazawa, Yoshiharu; Iwamatsu, Shigemi; Saito, Junichi; et al.
JAEA-Conf 2006-003, p.105 - 114, 2006/05
Irradiation assisted stress corrosion cracking (IASCC) caused by the simultaneous effects of radiation, stress and high temperature water environment is considered to be one of the critical concerns of in-core structural materials not only for light water reactors (LWRs) but also for water-cooled fusion reactors. In the research field of IASCC, post-irradiation examinations (PIEs) for irradiated materials have been mainly carried out, because there are many difficulties on SCC tests under neutron irradiation environment. Hence we have embarked on a development of the test techniques for performing the in-pile SCC tests. In this paper, we describe the developed several in-pile test techniques and the current status of in-pile SCC tests at Japan Materials Testing Reactor (JMTR).
Onuma, Ikuo*; Kainuma, Ryosuke*; Uda, Minoru*; Iwadachi, Takaharu*; Uchida, Munenori*; Kawamura, Hiroshi; Ishida, Kiyohito*
JAERI-Conf 2004-006, p.172 - 183, 2004/03
no abstracts in English
Maki, Yasuro*; Kitano, Koichi*; Inoue, Daiei*; Onuma, Hiroshi*; Komada, Hiroya*; Yamaji, Kenji*; Osumi, Takashi*; Tanaka, Hiroshi*; Imazu, Masanori*
JNC TJ1400 2005-005, 98 Pages, 1989/03
JNC-TJ1400-2005-005.pdf:2.98MB
no abstracts in English
Hagiya, Hiroyuki; Oku, Takayuki; Kira, Hiroshi; Shinohara, Takenao; Suzuki, Junichi; Takeda, Masayasu; Kakurai, Kazuhisa; Yokoyama, Makoto*; Nishihara, Yoshikazu*; Oba, Yojiro*; et al.
no journal, ,
no abstracts in English
Hagiya, Hiroyuki; Oku, Takayuki; Kira, Hiroshi; Shinohara, Takenao; Suzuki, Junichi; Kakurai, Kazuhisa; Yokoyama, Makoto*; Nishihara, Yoshikazu*; Mamiya, Hiroaki*; Oba, Yojiro*; et al.
no journal, ,
no abstracts in English
Onuma, Yuichi; Okada, Yuji; Hanawa, Hiroshi; Tsuchiya, Kunihiko; Kanno, Masaru
no journal, ,
The Japan Materials Testing Reactor (JMTR) has been refurbished for re-operation of 2011. As a part of the establishment of new irradiation facilities, technology development has been performed for the dismantling and removing of irradiation facilities such as OWL-1 (Oarai Water Loop No.1), OWL-2 (Oarai Water Loop No.2) and IASCC (Irradiation Assisted Stress Corrosion Cracking) facility installed in the JMTR cubicles. In this report, the study for dismantling and removing of irradiation facilities.
Hasegawa, Shin; Chen, J.; Koshikawa, Hiroshi; Iwase, Hiroki*; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari
no journal, ,
Radiation grafting of ethyl styrylsulfonate (EtSS) onto poly(ether ether ketone) (PEEK) film with various crystallinity was performed. The crystallinity in the range of 10 - 30% has strong influence on the grafting degrees. The PEEK film with crystallinity of 11 - 25% showed any dose effect on grafting degrees with 60%. By SAXS analysis, it was found that grafting process strongly depended on lamellar structure into PEEK membrane. The obtained PEEK-based polymer electrolyte membranes with about 12 
m thickness showed higher power density than that of Nafion in fuel cell test.
