Yasuda, Hiroshi*; Fumoto, Hiromichi*; Saito, Tatsuo
Nihon Genshiryoku Gakkai-Shi ATOMO, 63(8), p.610 - 614, 2021/08
Regarding the handling of uranium bearing waste, which is contaminated with uranium, which is a naturally occurring radionuclide, and its descendant nuclides, in recent years, the Japan Nuclear Regulatory Commission, etc. have been carefully and actively deliberated based on the knowledge of natural science and safety engineering. It was carried out, and as of March 2021, a certain policy has been shown. On the other hand, when disposing of uranium waste, which may cause dose exposure to future generations, the authors consider not only the science and engineering perspectives that have been conducted so far, but also the humanities and social science perspectives. We have been discussing with experts in related fields, thinking that it is necessary. In this report, we will introduce the background that brought about such an idea and the direction of future discussions.
Saito, Tatsuo; Kobayashi, Shinichi*; Zaitsu, Tomohisa*; Shimo, Michikuni*; Fumoto, Hiromichi*
Hoken Butsuri (Internet), 55(2), p.86 - 91, 2020/06
Safety cases for disposal of uranium bearing waste and NORM with uranium has not yet been fully developed in Japan, because of safety assessment of extraordinary long timespan and uncertainty in unexpected incidents with uncompleted radon impact evaluation measures arising from uranium waste disposal facility in far future. Our task group of radiation protection for wastes with natural radioactive nuclides studied some safety cases with disposal of uranium bearing waste and NORM in terms of nuclides, U-235, U-238 and their progenies, and comprehensively discussed the current state of their disposal in comparison to the ideas of international organizations such as ICRP and IAEA. We developed our ideas for long term uncertainty and radon with the knowledge of experts in each related area of direction, repeating discussions, focusing out the orientation of each directions, and outlined the recommendations with our suggestions of solving important issues in the future to be addressed.
Ito, Hiromichi*; Ota, Katsu; Kawahara, Hirotaka; Kobayashi, Tetsuhiko; Takamatsu, Misao; Nagai, Akinori
JAEA-Technology 2016-008, 87 Pages, 2016/05
In the experimental fast reactor Joyo, as a part of the restoration work of a partial dysfunction of fuel handling, the replacement of the upper core structure (UCS) was started from March 2014, and was completed in December 2014. In the jack-up test, the UCS was jacked-up to 1000 mm without significant sodium shearing resistance and interference. In the replacement of the UCS, a procedure was prepared with the use of wire-jack equipment assuming the interference. As a result, with the procedure and wire-jack were effectively functioned, the work was successfully completed.
Takamatsu, Misao; Kawahara, Hirotaka; Ito, Hiromichi; Ushiki, Hiroshi; Suzuki, Nobuhiro; Sasaki, Jun; Ota, Katsu; Okuda, Eiji; Kobayashi, Tetsuhiko; Nagai, Akinori; et al.
Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(1), p.32 - 42, 2016/03
In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test sub-assembly of "MARICO-2" (material testing rig with temperature control) had been broken and bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). This paper describes the results of the in-vessel repair techniques for UCS replacement, which are developed in Joyo. UCS replacement was successfully completed in 2014. In-vessel repair techniques for sodium cooled fast reactors (SFRs) are important in confirming its safety and integrity. In order to secure the reliability of these techniques, it was necessary to demonstrate the performance under the actual reactor environment with high temperature, high radiation dose and remained sodium. The experience and knowledge gained in UCS replacement provides valuable insights into further improvements for In-vessel repair techniques in SFRs.
Ito, Hiromichi; Suzuki, Nobuhiro; Kobayashi, Tetsuhiko; Kawahara, Hirotaka; Nagai, Akinori; Sakao, Ryuta*; Murata, Chotaro*; Tanaka, Junya*; Matsusaka, Yasunori*; Tatsuno, Takahiro*
Proceedings of 2015 International Congress on Advances in Nuclear Power Plants (ICAPP 2015) (CD-ROM), p.1058 - 1067, 2015/05
In the experimental fast reactor Joyo (Sodium-cooled Fast Reactor (SFR)), it was confirmed that the top of the irradiation test sub-assembly had bent onto the in-vessel storage rack as an obstacle and had damaged the upper core structure (UCS). There is a risk of deformation of the UCS and guide sleeve (GS) caused by interference between them unless inclination is controlled precisely. To mitigate the risk, special jack-up equipment for applying three-point suspension was developed. The existing damaged UCS (ed-UCS) jack-up test using the jack-up equipment was conducted on May 7, 2014. As a result of this test, it was confirmed that the ed-UCS could be successfully jacked-up to 1000 mm without consequent overload. The experience and knowledge gained in the ed-UCS jack-up test provides valuable insights and prospects not only for UCS replacement but also for further improving and verifying repair techniques in SFRs.
Ito, Hiromichi; Takamatsu, Misao; Kawahara, Hirotaka; Nagai, Akinori
JAEA-Technology 2014-024, 28 Pages, 2014/07
Because the gap between the UCS and rotation plug's guide sleeve is 5 mm in minimum, there is a risk of deformation of the UCS and guide sleeve with interference between UCS and guide sleeve in the UCS replacement work. In order to reduce the risk, R&D for below subjects is required.(1) UCS jack-up equipment with strict control of inclination, (2) Detection and escape method for interference between UCS and guide sleeve. In order to solve above (1), the jack-up equipment with applying three-point suspension is developed. Then, in the aspect of above (2), load-measuring devices are installed on three jacks of jack-up equipment. By means of detection eccentric load with interference, deformation of UCS and guide sleeve are prevented. And also, the location of interference can be investigated based on eccentric loads of three jacks. The performance is verified in the ex-vessel mock-up test using full-scale dummy of UCS.
Saito, Tatsuo; Sakai, Akihiro; Sato, Kazuhiko; Yagi, Naoto; Hata, Haruhi; Fumoto, Hiromichi*; Kawagoshi, Hiroshi; Hasegawa, Makoto
JAEA-Review 2014-021, 30 Pages, 2014/07
Japan Atomic Energy Agency surveyed the reference cases for the disposal of uranium bearing waste in low activity concentration as the contents of their own category 2 waste disposal facility for the Research and Development Activities. We reviewed the concepts mentioned in IAEA and ICRP documents, reference cases of uranium bearing waste disposal in selected countries (USA, Canada, UK, France and Sweden), and the disposal styles of long-lived radioactive waste were summarized, and the action items for application to the disposal system of our country was arranged. The disposal facilities in selected countries can be classified into 2 types with the length of performance assessment period for intruder scenario. They are long term assessment type and short term assessment type. It seems that the disposal system construction in category 2 waste disposal is the most realistic since there are many precedence examples of each country. Correspondence of 2 types of these disposal facilities is useful as a reference case.
Sato, Kazuhiko; Sakai, Akihiro; Hata, Haruhi; Fumoto, Hiromichi*; Kawagoshi, Hiroshi; Saito, Tatsuo; Hasegawa, Makoto
JAEA-Review 2014-006, 78 Pages, 2014/03
In this paper, we report the result of survey for basic principle of safety assessment for long-lived low-level (LL-LL) waste disposal and experience of the industrial waste disposal sites for uranium bearing waste in France, UK and Sweden, following the report of survey for U.S.A. and Canada published in December 2013.
Okuda, Eiji; Ito, Hiromichi; Yoshihara, Shizuya
UTNL-R-0486, p.6_1 - 6_10, 2014/03
An accident occurred in experimental fast reactor "Joyo" in 2007 which is obstruction of fuel change equipment caused by contacting rotating plug and MARICO-2. In addition, we confirmed two happenings in the reactor vessel that (1) Deformation of MARICO-2 subassembly on the in vessel storage rack together with a transfer pot, (2) Deformation of the Upper core structure of "Joyo" caused by contacting MARICO-2 subassembly and the UCS. We do the restoration work for restoring it. This time, we describe current status of Replacement work of the UCS.
Hasegawa, Makoto; Saito, Tatsuo; Zaitsu, Tomohisa; Sato, Kazuhiko; Sakai, Akihiro; Fumoto, Hiromichi*
JAEA-Review 2013-043, 42 Pages, 2013/12
Uranium bearing waste in Japan is not included in Category-2 radioactive waste disposal in NSCRG: F-RW-I.02 (published in August 2010, NSC Japan). Therefore, disposal of uranium bearing waste should be considered in institutionalization. In charge of the consideration, it is thought effective to refer to the proven tactics of the uranium waste disposal in overseas and the information on a safe regulatory system. Since the view of regulations and enterprises in this field are progressing day by day, renewal of the existing information of disposal of the uranium waste in each country is required. Furthermore, amendment of the U.S. federal rule aiming at safety disposal of depleted uranium is in progress. It is important to collect and arrange the latest information on the two above-mentioned points. Therefore, it visited the disposal responsible organization and regulatory agency of the disposal site of the uranium waste in the U.S. and Canada, and held institution investigations and interviews paying attention to the following four items: (1) "amendment of the U.S. 10CFR61", (2) "Safety evaluation of uranium bearing waste", (3) "Disposal site design", (4) "Stakeholder involvement".
Nakajima, Kenji; Kawamura, Seiko; Kikuchi, Tatsuya; Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Aizawa, Kazuya; Suzuya, Kentaro; Shibata, Kaoru; et al.
Journal of the Physical Society of Japan, 80(Suppl.B), p.SB028_1 - SB028_6, 2011/05
AMATERAS is a cold-neutron disk-chopper spectrometer in MLF, J-PARC. The construction of main part of the spectrometer has been completed in spring of 2009. Soon after that, we have started the commissioning work on AMATERAS. The performance of AMATERAS has been examined by test experiments in the course of commissioning. In parallel to these works, we have started the user program on AMATERAS from December 2009 and we are getting scientific results from our spectrometer. In this presentation, we will report the current status of AMATERAS including the results of performance tests and some of examples of scientific outputs.
Toyoshima, Atsushi; Haba, Hiromitsu*; Tsukada, Kazuaki; Asai, Masato; Akiyama, Kazuhiko*; Goto, Shinichi*; Ishii, Yasuo; Nishinaka, Ichiro; Sato, Tetsuya; Nagame, Yuichiro; et al.
Radiochimica Acta, 96(3), p.125 - 134, 2008/03
Formation of an anionic fluoride-complex of element 104, rutherfordium (Rf) produced in the Cm(O,5n)Rf reaction was studied by an anion-exchange method based on an atom-at-a-time scale. It was found that the hexafluoro complex of Rf, [RfF], was formed in the studied fluoride ion concentrations of 0.0005 - 0.013 M. Formation of [RfF] was significantly different from that of the homologues Zr and Hf, [ZrF] and [HfF]; the evaluated formation constant of [RfF] is at least one-order of magnitude smaller than those of [ZrF] and [HfF].
Sakazume, Yoshinori; Aoki, Hiromichi; Haga, Takahisa; Fukaya, Hiroyuki; Sonoda, Takashi; Shimizu, Kaori; Niitsuma, Yasushi*; Ito, Mitsuo; Inoue, Takeshi
JAEA-Technology 2007-069, 44 Pages, 2008/02
Analysis of the uranyl nitrate solution fuel is carried out at the analytical laboratory of NUCEF (Nuclear Fuel Cycle Engineering Research Facility), which provides essential data for operation of STACY (Static Experiment Critical Facility), TRACY (Transient Experiment Critical Facility) and the fuel treatment system. Analyzed in FY 2006 were uranyl nitrate solution fuel samples taken before and after experiments of STACY and TRACY, samples for the preparation of uranyl nitrate solution fuel, and samples for nuclear material accountancy purpose. The total number of the samples analyzed in FY 2006 was 254. This report summarizes work related to the analysis and management of the analytical laboratory in the FY 2006.
Nagame, Yuichiro; Tsukada, Kazuaki; Asai, Masato; Toyoshima, Atsushi; Akiyama, Kazuhiko; Ishii, Yasuo; Sato, Tetsuya; Hirata, Masaru; Nishinaka, Ichiro; Ichikawa, Shinichi; et al.
Radiochimica Acta, 93(9-10), p.519 - 526, 2005/00
no abstracts in English
Saito, Takeru; Yamamoto, Hiroyuki; Yamaguchi, Kenji; Nakanoya, Takamitsu; Hojo, Kiichi; Haraguchi, Masaharu*; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Tanaka, Tomoaki*; Shimada, Hiromichi*
Nuclear Instruments and Methods in Physics Research B, 206, p.321 - 325, 2003/05
no abstracts in English
Matsuda, Hideo*; Omura, Ichiro*; Sakiyama, Yoko*; Urano, Satoshi*; Iesaka, Susumu*; Ohashi, Hiromichi*; Hirao, Toshio; Abe, Hiroshi; Ito, Hisayoshi; Mori, Hidenobu; et al.
JAERI-Review 2002-035, TIARA Annual Report 2001, p.11 - 13, 2002/11
no abstracts in English
Saito, Takeru; Yamamoto, Hiroyuki; Asaoka, Hidehito; Haraguchi, Masaharu*; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Tanaka, Tomoaki*; Shimada, Hiromichi*; Hojo, Kiichi
Analytical Sciences (CD-ROM), 17(Suppl.), p.1073 - 1076, 2002/03
no abstracts in English
Matsubayashi, Nobuyuki*; Tanaka, Tomoaki*; Imamura, Motoyasu*; Shimada, Hiromichi*; Saito, Takeru
Analytical Sciences (CD-ROM), 17(Suppl.), p.119 - 121, 2002/03
no abstracts in English
Bando, Kyoko*; Saito, Takeru; Sato, Koichi*; Tanaka, Tomoaki*; Dumeignil, F.*; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Shimada, Hiromichi*
Topics in Catalysis, 18(1-2), p.59 - 65, 2002/01
no abstracts in English
Saito, Takeru; Yamamoto, Hiroyuki; Haraguchi, Masaharu*; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Tanaka, Tomoaki*; Shimada, Hiromichi*; Hojo, Kiichi
Photon Factory Activity Report 2001, (19), P. 205, 2001/00
no abstracts in English