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Sato, Takumi; Otobe, Haruyoshi; Morishita, Kazuki; Marufuji, Takato; Ishikawa, Takashi; Fujishima, Tadatsune; Nakano, Tomoyuki
JAEA-Technology 2023-016, 41 Pages, 2023/09
This report summarizes the results of the stabilization treatments of post-experiment nuclear materials in Plutonium Fuel Research Facility (PFRF) from August 2018 to March 2021. Based on the management standards for nuclear materials enacted after the contamination accident that occurred at PFRF on June 6, 2017, the post-experiment nuclear materials containing plutonium (Pu): samples mixed with organic substances that cause an increase in internal pressure due to radiolysis (including X-ray diffraction samples mixed with epoxy resin and plutonium powder which caused contamination accidents), carbides and nitrides samples which is reactive in air, and chloride samples which may cause corrosion of storage containers, were selected as targets of the stabilization. The samples containing organic materials, carbides and nitrides were heated in an air flow at 650 C and 950 C for 2 hours respectively to remove organic materials and convert uranium (U) and Pu into oxides. U and Pu chlorides in LiCl-KCl eutectic melt were reduced and extracted into liquid Cd metal by a reaction with lithium (Li) -cadmium (Cd) alloy and converted to U-Pu-Cd alloy at 500 C or higher. All of the samples were stabilized and stored at PFRF. We hope that the contents of this report will be utilized to consider methods for stabilizing post experiment nuclear materials at other nuclear fuel material usage facilities.
Tanaka, Kosuke; Sato, Isamu*; Onishi, Takashi; Ishikawa, Takashi; Hirosawa, Takashi; Katsuyama, Kozo; Seino, Hiroshi; Ohno, Shuji; Hamada, Hirotsugu; Tokoro, Daishiro*; et al.
Journal of Nuclear Materials, 536, p.152119_1 - 152119_8, 2020/08
Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)In order to obtain the release rate coefficients from fuels for fast reactors (FRs), heating tests and the subsequent analyses of the fission products (FPs) and actinides that are released were carried out using samples of uranium-plutonium mixed oxide (MOX) fuel pellets irradiated at the experimental fast reactor Joyo. Three heating tests targeting temperatures of 2773, 2973 and 3173 K were conducted using an FP release behavior test apparatus equipped with a high-frequency induction furnace and solid FP sampling systems consisting of a thermal gradient tube (TGT) and filters. Irradiated fuel pellets were placed into a tungsten crucible, then loaded into the induction furnace. The temperature was raised continuously at a heating rate of 10 K/s to the targeted temperature and maintained for 500 s in a flowing argon gas atmosphere. The FPs and actinides released from the MOX fuels and deposited in the TGT and filters were quantified by gamma-ray spectrometry and inductively coupled plasma mass spectrometry (ICP-MS) analysis. Based on the analysis, the release rates of radionuclides from MOX fuels for FR were obtained and compared with literature data for light water reactor (LWR) fuels. The release rate coefficients of FPs obtained in this study were found to be similar to or lower than the literature values for LWR fuels. It was also found that the release rate coefficient data for actinides were within the range of variation of literature values for LWR fuels.
Ito, Chikara; Naito, Hiroyuki; Ishikawa, Takashi; Ito, Keisuke; Wakaida, Ikuo
JPS Conference Proceedings (Internet), 24, p.011038_1 - 011038_6, 2019/01
A high-radiation resistant optical fiber has been developed in order to investigate the interiors of the reactor pressure vessels and the primary containment vessels at the Fukushima Daiichi Nuclear Power Station. The tentative dose rate in the reactor pressure vessels is assumed to be up to 1 kGy/h. We developed a radiation resistant optical fiber consisting of a 1000 ppm hydroxyl doped pure silica core and 4 % fluorine doped pure silica cladding. We attempted to apply the optical fiber to remote imaging technique by means of fiberscope. The number of core image fibers was increased from 2000 to 22000 for practical use. The transmissive rate of infrared images was not affected after irradiation of 1 MGy. No change in the spatial resolution of the view scope by means of image fiber was noted between pre- and post-irradiation. We confirmed the applicability of the probing system, which consists of a view scope using radiation-resistant optical fibers.
Ishikawa, Takashi; Onishi, Takashi; Hirosawa, Takashi; Tanaka, Kosuke; Katsuyama, Kozo
Proceedings of 54th Annual Meeting of Hot Laboratories and Remote Handling (HOTLAB 2017) (Internet), 10 Pages, 2017/00
Ito, Chikara; Naito, Hiroyuki; Oba, Hironori; Saeki, Morihisa; Ito, Keisuke; Ishikawa, Takashi; Nishimura, Akihiko; Wakaida, Ikuo; Sekine, Takashi
Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 7 Pages, 2014/07
A high-radiation resistant optical fiber has been developed in order to investigate the interiors of the reactor pressure vessels and the primary containment vessels of the Fukushima Daiichi Nuclear Power Station. The radiation resistance of an optical fiber was improved by increasing the amount of hydroxyl up to 1000 ppm in pure silica fiber. The improved image fiber consists of common cladding and a large number of fiber cores made from pure silica that contains 1000 ppm hydroxyl. The transmissive rate of an infrared image was not affected after the irradiation of 1 MGy. We have developed the fiber-coupled LIBS system to detect plasma emission efficiently in near-infrared region. In addition, we have performed a ray dose rate measurement using an optical fiber of which scintillator is attached to the tip. As a result, the concept of applicability of a probing system using the high-radiation resistant optical fibers has been confirmed.
Ito, Chikara; Ito, Keisuke; Ishikawa, Takashi; Yoshida, Akihiro; Sanada, Yukihisa; Torii, Tatsuo; Notomi, Akihiro*; Wakabayashi, Genichiro*; Miyazaki, Nobuyuki*
Hoshasen, 39(1), p.7 - 11, 2013/09
no abstracts in English
Aoyama, Takafumi; Ishikawa, Takashi; Ito, Chikara; Iwata, Yoshihiro; Harano, Hideki*
Transactions of the American Nuclear Society, 106(1), p.611 - 613, 2012/06
We studied the failed fuel detection and location (FFDL) system by means of laser resonance ionization mass spectrometry (RIMS). The applicability of the RIMS system for Monju and its installation were investigated in this study. It was found that the RIMS is able to identify the neighboring tag gas which is used for Monju with the 68% reliability. The newly designed RIMS system can be accommodated in the present facility and can be connected to primary cover gas lines without affects to the current FFDL function of the conventional system.
*; ;
JAERI-M 84-051, 40 Pages, 1984/03
no abstracts in English
Ishikawa, Takashi; Kawahara, Hirotaka; Yamashita, Takuya; Tagawa, Akihiro; Komai, Masafumi*
no journal, ,
no abstracts in English
Ito, Chikara; Sanada, Yukihisa; Ito, Keisuke; Kondo, Atsuya; Ishikawa, Takashi; Nakano, Hironobu; Nozaki, Tatsuo; Torii, Tatsuo; Notomi, Akihiro*
no journal, ,
no abstracts in English
Miyahara, Shinya; Aoyama, Takafumi*; Ishikawa, Takashi; Ito, Chikara; Iwata, Yoshihiro; Harano, Hideki*
no journal, ,
We studied the Failed Fuel Detection and Location (FFDL) system by means of laser Resonance Ionization Mass Spectrometry (RIMS). The applicability of the RIMS system for Monju and its installation were investigated in this study. It was found that the RIMS is able to identify the neighboring tag gas which is used for Monju with the 68% reliability. The newly designed RIMS system can be accommodated in the present facility and can be connected to primary cover gas lines without affects to the current FFDL function of the conventional system.
Aoyama, Takafumi; Ishikawa, Takashi; Iwata, Yoshihiro; Ito, Chikara; Morohashi, Yuko; Takeda, Toshikazu*
no journal, ,
no abstracts in English
Aoyama, Takafumi; Ishikawa, Takashi; Iwata, Yoshihiro; Ito, Chikara
no journal, ,
no abstracts in English
Aoyama, Takafumi; Takeda, Toshikazu*; Ishikawa, Takashi; Iwata, Yoshihiro; Ito, Chikara; Morohashi, Yuko
no journal, ,
The high sensitivity FFDL technique for SFR has been developed using the RIMS method. The RIMS method was demonstrated by measuring the artificially blended xenon and krypton gas which was used for the pressurized steel capsule of in-pile creep rupture experiment in the experimental fast reactor Joyo. The measured isotopic ratio of xenon collected from the Joyo reactor cover gas by means of RIMS could successfully identify the ruptured capsule of which tag gas was contained. The RIMS was then applied for the proto type fast breeder reactor Monju. The RIMS system can also detect stable xenon nuclides and radioactive Xe-133 in the collected from the Joyo reactor cover gas during the fuel failure simulation test, implying that the RIMS can apply to assume the burn-up of the failed fuel subassembly by using the ratio of stable and radioactive xenon isotopes.
Morohashi, Yuko; Suzuki, Satoshi; Ishikawa, Takashi
no journal, ,
The noble gas background concentration of the primary argon gas system was measured for the performance confirmation of tagginig gas method failed fuel detection and location (FFDL) system of prototype fast breeder reactor "MONJU". And in order to check the validity of measured value by FFDL, it analyzed by laser resonance ionization mass spectrometry (RIMS).
Ito, Keisuke; Ishikawa, Takashi; Naito, Hiroyuki; Ito, Chikara
no journal, ,
no abstracts in English
Ishikawa, Takashi; Ito, Keisuke; Naito, Hiroyuki; Ito, Chikara; Sekine, Takashi
no journal, ,
no abstracts in English
Ito, Chikara; Naito, Hiroyuki; Ito, Keisuke; Ishikawa, Takashi; Nishimura, Akihiko; Oba, Hironori; Saeki, Morihisa; Wakaida, Ikuo
no journal, ,
no abstracts in English
Ishikawa, Takashi; Tanaka, Kosuke; Sato, Isamu*; Onishi, Takashi; Hirosawa, Takashi; Seino, Hiroshi; Ohno, Shuji; Hamada, Hirotsugu; Tokoro, Daishiro*; Sekioka, Ken*; et al.
no journal, ,
no abstracts in English
Onishi, Takashi; Tanaka, Kosuke; Sato, Isamu*; Ishikawa, Takashi; Hirosawa, Takashi; Katsuyama, Kozo; Seino, Hiroshi; Ohno, Shuji; Hamada, Hirotsugu; Tokoro, Daishiro*; et al.
no journal, ,
no abstracts in English