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Nishino, Hiroyuki; Kurisaka, Kenichi; Naruto, Kenichi*; Gondai, Yoji; Yamamoto, Masaya
Proceedings of 30th International Conference on Nuclear Engineering (ICONE30) (Internet), 10 Pages, 2023/05
The effectiveness evaluation of safety measures against severe accident is necessary for restart of experimental sodium-cooled fast reactor "Joyo" in Japan. These safety measures correspond to those in defense-in-depth (DiD) level 4. In the previous study, a level-1 probabilistic risk assessment (PRA) at power was performed to calculate frequencies of the accident sequences of failure of safety measures in DiD level 1 to 3, to identify dominant accident sequence groups, and to identify dominant accident sequence for selecting important accident sequences in each accident sequence group which are needed for implementing the effectiveness evaluation of safety measures in DiD level 4. Based on this, the present study implemented level-1 PRA at power to show quantitatively reduction of those occurrence frequency by the safety measure in the DiD level 4. As the result, the frequency of each accident sequence group decreased significantly, and total frequency of the accident sequence groups decreased to about 1
10
/reactor-year which is about 1/1000 times the one estimated in the previous study. The protected loss of heat sink was the largest contributor in all the accident groups and a dominant accident sequence in each accident group was also identified in this study.
Nishino, Hiroyuki; Kurisaka, Kenichi; Naruto, Kenichi*; Gondai, Yoji; Yamamoto, Masaya; Yamano, Hidemasa
Proceedings of Asian Symposium on Risk Assessment and Management 2020 (ASRAM 2020) (Internet), 12 Pages, 2020/11
The objective of this study is to evaluate the occurrence frequency of accident sequences which may lead to core damage if provisions in defense in depth (DiD) level 1 to 3 are the only safety measures. For this objective, the existing safety measures in this SFR are categorized into those for the DiD level 1-3 and those for the DiD level 4. The safety measures for the DiD level 1-3 are as follows; (1) main reactor shutdown system, (2) double boundary structure in the primary main and auxiliary cooling system and the reactor vessel, which maintain the reactor coolant level sufficient for coolant circulation in the primary main cooling system, (3) decay heat removal in a forced circulation mode. Accident sequences are categorized into typical SFR-specific groups and station blackout (SBO) in this study. The SFR-specific groups are unprotected loss of flow, unprotected transient over power, unprotected loss of heat sink, loss of reactor level, and protected loss of heat sink (PLOHS). The occurrence frequency of these accident sequence groups was quantified to identify major contributors. As the result, PLOHS excluding SBO was indicated as the dominant contribution of 80% or more in the all accident sequence groups and the annual occurrence frequency of the PLOHS was 1.0E-4 order of magnitude. For the PLOHS, loss of offsite power (LOOP) was indicated as major contribution of 30% in initiating events. In the accident sequences of the PLOHS initiated from LOOP, a dominant sequence was combination of common cause failure of primary pumps in the main cooling system and failure-to-start of the auxiliary cooling system after LOOP. The second dominant contribution (15% or more) in the all accident sequence groups is PLOHS in SBO (i.e., decay heat removal failure due to SBO). Each of the other accident sequence groups was 1%.
Kawahara, Hirotaka; Yamamoto, Masaya; Tomita, Etsuo; Takamatsu, Misao
JAEA-Technology 2012-030, 50 Pages, 2012/09
JAEA-Technology-2012-030.pdf:6.16MB
JAEA-Technology-2012-030-appendix(CD-ROM).zip:21.06MB
In the experimental fast reactor Joyo, in-vessel observation results showed that 6 pins which were connected between the handling head and the wrapper tube joint of the instrumented test subassembly (MARICO-2) were disconnected. Therefore, in order to confirm whether the disconnected 6 pins will influence reactor's safety or not, loose parts behavior in the reactor vessel was evaluated.
Furukawa, Tomohiro; Kato, Shoichi; Maeda, Shigetaka; Yamamoto, Masaya; Sekine, Takashi; Ito, Chikara
JAEA-Research 2011-039, 20 Pages, 2012/02
JAEA-Research-2011-039.pdf:3.4MB
Application of zirconium alloy as a neutron reflector around the driver fuel region of the Japanese experimental fast reactor JOYO has been planned for a further increase of core average burn-up. In order to investigate the compatibility of the zirconium alloys with high-temperature sodium which is coolant of the JOYO, corrosion test in sodium and tensile test of the exposed alloys were performed. The corrosion test was done at 500
C and 650C in stagnant/flowing sodium for two kinds of zirconium alloys, and then weight change measurement and metallurgical observation were carried out. The tensile test was performed in air at the same temperature with the sodium exposure.
Maeda, Shigetaka; Yamamoto, Masaya; Soga, Tomonori; Sekine, Takashi; Aoyama, Takafumi
Journal of Nuclear Science and Technology, 48(4), p.693 - 700, 2011/04
Core modification was investigated to further increase the core burn-up of the experimental fast reactor Joyo. This modification also enables the core to accommodate more irradiation test subassemblies that have lower fissile material content compared to the driver fuel. The design calculations showed that the replacement of the radial reflector elements made of stainless steel with those made of zirconium of nickel-base ally is effective in improving neutron efficiency. The irradiation tests capacity can be increased by reducing the number of control rods based on the re-evaluation of the design margin in the control rod worth calculation. These modifications will be useful to save driver fuels and to enhance the Joyo's irradiation capability.
Donomae, Takako; Katsuyama, Kozo; Tachi, Yoshiaki; Maeda, Koji; Yamamoto, Masaya; Soga, Tomonori
Journal of Nuclear Science and Technology, 48(4), p.580 - 584, 2011/04
One of the challenges in developing a long-life control rod is to restrain absorber-cladding mechanical interaction (ACMI). Its lifetime was limited by ACMI, which is induced by the swelling and relocation of B
C pellets. To restrain ACMI, a shroud tube was inserted into the gap between the BC pellets and the cladding tube. And sodium was selected as bonding material instead of helium to restrain increases in the pellet temperature. As a result of these improvements, the estimated lifetime of the control rod at Joyo was doubled. In this paper, the results of post irradiation examination are reported.
Matsui, Yoshinori; Takahashi, Hiroyuki; Yamamoto, Masaya; Nakata, Masahito; Yoshitake, Tsunemitsu; Abe, Kazuyuki; Yoshikawa, Katsunori; Iwamatsu, Shigemi; Ishikawa, Kazuyoshi; Kikuchi, Taiji; et al.
JAEA-Technology 2009-072, 144 Pages, 2010/03
JAEA-Technology-2009-072.pdf:45.01MB
"R&D Project on Irradiation Damage Management Technology for Structural Materials of Long-life Nuclear Plant" was carried out from FY2006 in a fund of a trust enterprise of the Ministry of Education, Culture, Sports, Science and Technology. The coupled irradiations or single irradiation by JOYO fast reactor and JRR-3 thermal reactor were performed for about two years. The irradiation specimens are very important materials to establish of "Evaluation of Irradiation Damage Indicator" in this research. For the acquisition of the examination specimens irradiated by the JOYO and JRR-3, we summarized about the overall plan, the work process and the results for the study to utilize these reactors and some facilities of hot laboratory (WASTEF, JMTR-HL, MMF and FMF) of the Oarai Research-and-Development Center and the Nuclear Science Research Institute in the Japan Atomic Energy Agency.
Nakai, Satoru; Aoyama, Takafumi; Ito, Chikara; Yamamoto, Masaya; Iijima, Minoru; Nagaoki, Yoshihiro; Kobayashi, Atsuko; Onoda, Yuichi; Ohgama, Kazuya; Uwaba, Tomoyuki; et al.
Kosoku Jikkenro "Joyo" Rinkai 30-Shunen Kinen Hokokukai Oyobi Gijutsu Koenkai, 154 Pages, 2008/06
no abstracts in English
Ijiri, Yuji*; Hattori, Hiromichi*; Suzuki, Shunichi*; Oishi, Masaya*; Kubota, Shigeru*; Adachi, Tetsuya*; Yamamoto, Takuya*
JNC TJ8400 2001-010, 143 Pages, 2001/03
JNC-TJ8400-2001-010.pdf:17.19MB
The evaluation of uncertainty of geological environment is a key issue in assessing a performance of a deep geological disposal system for high-level nuclear waste. The geological environment uncertainty is arose from data obtained from surveys and model used for a performance assessment.The objectives of this study is to develop a rational planning methodology of site characterization using the Horonobe site as a model case, and to establish a modeling methodology using the Tono site as a model case. At the Horonobe site, first, a conceptual model is constructed based on the information at every stage of site characterization procedure. A sensitivity analysis is performed using various conceptual models and data. If conceptual models uncertainty have a great impact on the result of performance assessment analysis, surveys that detect the most appropriate conceptual model are conducted in the next stage of site characterization. If data uncertainty have a great impact on the result of performance assessment analysis, surveys that decrease the data uncertainty are conducted. Thus, a rational site characterization methodology in which the most sensitive items are preferentially detected in the next stage of site characterization is developed. This concept of a rational site characterization methodology is described in this report. In addition, preliminary conceptual model is developed based on geological information around Horonobe site, and data uncertainty for the sensitivity analysis which will be conducted in next year is investigated. At the Tono site, literature on model uncertainty is surveyed, and data obtained at the Tono site is reviewed from modeling point of view.
Ijiri, Yuji*; Hattori, Hiromichi*; Suzuki, Shunichi*; Oishi, Masaya*; Kubota, Shigeru*; Adachi, Tetsuya*; Yamamoto, Takuya*; Igarashi, Takafumi*; Sugihara, Yutaka*
JNC TJ8400 2001-009, 41 Pages, 2001/03
JNC-TJ8400-2001-009.pdf:6.69MB
no abstracts in English
Anezaki, Susumu*; Sugihara, Yutaka*; Igarashi, Takafumi*; Yamamoto, Takuya*; Adachi, Tetsuya*; Suzuki, Shunichi*; Oishi, Masaya*
JNC TJ1410 2000-001, 123 Pages, 2000/03
Matsui, Yoshinori; Nabeya, Hideaki; Kusunoki, Tsuyoshi; Takahashi, Hiroyuki; Aizawa, Masao; Nakata, Masahito; Numata, Masami; Usami, Koji; Endo, Shinya; Ito, Kazuhiro; et al.
no journal, ,
We are proceeding with the study of "R&D Project on Irradiation Damage Management Technology for Structural Materials of Long-life Nuclear Plant". For the study, it is important that the irradiated specimens are gotten by the coupling of JRR-3 and JOYO. This reports the total irradiation plan in the study, and the executed work for the coupling irradiation (JRR-3 and JOYO) including the Hot facilities work of Tokai and Oarai in the 2006 fiscal year.
Yamamoto, Masaya; Okawachi, Yasushi; Ito, Hideaki; Aoyama, Takafumi
no journal, ,
no abstracts in English
Itagaki, Wataru; Kitamura, Ryoichi; Yamamoto, Masaya; Abe, Kazuyuki
no journal, ,
no abstracts in English
Itagaki, Wataru; Soga, Tomonori; Yamamoto, Masaya; Sekine, Takashi
no journal, ,
no abstracts in English
Ito, Kazuhiro; Yamamoto, Masaya; Maeda, Koji; Akasaka, Naoaki; Harada, Akio; Konashi, Kenji*
no journal, ,
As part of "Development of Hydride Neutron Absorber for Fast Reactor", a series of neutron irradiation experiment with in HfH, (Gd+ZR)H and stainless steel specimens was performed in experimental fast reactor Joyo. Here, the stainless steel specimens were coated by oxide film to simulate a cladding tube. In this report, the irradiation examination plan and a result were summarized.
Katsuyama, Kozo; Yamamoto, Masaya; Abe, Kazuyuki; Maeda, Koji; Nagamine, Tsuyoshi; Nakamura, Yasuo
no journal, ,
no abstracts in English
Soga, Tomonori; Yamamoto, Masaya; Sekine, Takashi; Aoyama, Takafumi
no journal, ,
The standard control rod in the fast reactor bundles the control elements which contain boron carbide pellets as neutron absorber in the stainless steel cladding tube. The lifetime of the control rod in the experimental fast reactor Joyo, is limited to approximately 4010
/cm
by the Absorber Cladding Mechanical Interaction (ACMI) which originates from relocation and swelling of the boron carbide pellets. The sodium bonded control rod, which has a shroud tube, has been developed to attempt a lifetime extension by solving this problem as a part of the development of control rod in the fast reactor. The first sodium bonded control rod has been used since the 1st operation cycle of MK-III core. The maximum burn-up is achieved to 10010/cm which is approximately 2.5 times of the conventional control rods in Joyo.
Matsui, Yoshinori; Takahashi, Hiroyuki; Ichise, Kenichi; Usami, Koji; Endo, Shinya; Iwamatsu, Shigemi; Yonekawa, Minoru; Ito, Kazuhiro; Yamamoto, Masaya; Soga, Tomonori; et al.
no journal, ,
"R&D Project on Irradiation Damage Management Technology for Structural Materials of Long-life Nuclear Plant" was carried out from 2006 fiscal year in a fund of a trust enterprise of the Ministry of Education, Culture, Sports, Science and Technology. The coupling irradiations or single irradiations by JOYO fast reactor and JRR-3 fission reactor were performed for about two years. The irradiation specimens are the very important materials to establish of "Evaluation of Irradiation Damage Indicator" in this research. For the acquisition of the examination specimens irradiated by the JOYO and JRR-3, we will present about the overall plan, work process and the results for the study to utilize these reactors and some facilities of hot laboratory (WASTEF, JMTR-HL, MMF and FMF) of the Oarai Research-and-Development Center and the Nuclear Science Research Institute in the Japan Atomic Energy Agency.
Kawahara, Hirotaka; Iseki, Atsushi; Yamazaki, Manabu; Yamamoto, Masaya; Takamatsu, Misao; Ishikawa, Koki; Kurisaka, Kenichi; Aoyama, Takafumi
no journal, ,
no abstracts in English
