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Okada, Yuji; Amaya, Masaki
Annals of Nuclear Energy, 136, p.107028_1 - 107028_9, 2020/02
Times Cited Count：0Mano, Akihiro; Katsuyama, Jinya; Miyamoto, Yuhei*; Yamaguchi, Yoshihito; Li, Y.
International Journal of Pressure Vessels and Piping, 179, p.103945_1 - 103945_6, 2020/01
Weld residual stress (WRS) is one of the most important factors in the structural integrity assessment of piping welds, and it is considered a driving force for crack growth. It is characterized by large uncertainty. For more rational assessment, it is important to consider the uncertainty of WRS for evaluating crack growth behavior in probabilistic fracture mechanics (PFM) analysis. In existing PFM analysis codes, WRS uncertainty is set by statistically processing the results of multiple finite element analyses. This process depends on the individual performing PFM analysis, which may lead to uncertainties whose sources would be different from the original WRS. In this study, we developed a new WRS evaluation model based on Fourier transformation, and the model was incorporated into PASCAL-SP, which has been developed by Japan Atomic Energy Agency. Through improvements to the code, WRS uncertainty can be considered automatically and appropriately by inputting multiple WRS analysis results directly as input data for PFM analysis.
Narukawa, Takafumi; Amaya, Masaki
Journal of Nuclear Science and Technology, 57(1), p.68 - 78, 2020/01
Times Cited Count：0 Percentile：100(Nuclear Science & Technology)Wada, Yuki; Le, T. D.; Satou, Akira; Shibamoto, Yasuteru; Yonomoto, Taisuke
Journal of Nuclear Science and Technology, 57(1), p.100 - 113, 2020/01
Times Cited Count：0 Percentile：100(Nuclear Science & Technology)Ono, Takuya; Tashiro, Shinsuke; Amano, Yuki; Yoshida, Ryoichiro; Abe, Hitoshi
Nuclear Technology, 206(1), p.40 - 47, 2020/01
Times Cited Count：0Recent Japanese nuclear regulations have focused on the hazards of in-cell solvent fires at reprocessing facilities. In this work, a mixture of tributyl phosphate and dodecane-based solvents was burned to generate an aerosol composed of soot and unburned solvent that was then loaded onto a high-efficiency particulate air filter simulating the ventilation system of reprocessing facilities. A radical increase of differential pressure occurred in the filters during these tests after the dodecane burned out from the solvent in a phenomenon we named as rapid clogging, likely caused by the burnout of dodecane. This relationship provides valuable insight into the establishment of new regulations for reprocessing facilities. This work indicates that clogging of ventilation filters during solvent fires may occur more rapidly than previously estimated.
Mori, Airi; Takahara, Shogo; Yoshida, Hiroko*; Sanada, Yukihisa; Munakata, Masahiro
Health Physics, 117(6), p.606 - 617, 2019/12
Times Cited Count：0 Percentile：100(Environmental Sciences)
6 rod bundleHan, X.*; Shen, X.*; Yamamoto, Toshihiro*; Nakajima, Ken*; Sun, Haomin; Hibiki, Takashi*
International Journal of Heat and Mass Transfer, 144, p.118696_1 - 118696_19, 2019/12
Times Cited Count：0 Percentile：100(Thermodynamics)Satou, Akira; Wada, Yuki; Shibamoto, Yasuteru; Yonomoto, Taisuke
Nuclear Engineering and Design, 354, p.110164_1 - 110164_10, 2019/12
Times Cited Count：0 Percentile：100(Nuclear Science & Technology)JAEA has conducted a series of experimental researches on the Post-boiling transition heat transfer, transient critical heat flux and rewetting for BWRs. Experimental data bases covering the anticipated operational conditions was developed; the significance of the precursor cooling was identified. This paper presents approaches of the present research focusing on the anticipated transient without scram, effects of the spacer and physical understanding of the phenomena for development of mechanistic model together with promising results obtained so far.
Ha, Yoosung; Takamizawa, Hisashi; Katsuyama, Jinya; Hanawa, Satoshi; Nishiyama, Yutaka
Nuclear Instruments and Methods in Physics Research B, 461, p.276 - 282, 2019/12
Times Cited Count：0 Percentile：100(Instruments & Instrumentation)Negyesi, M.; Amaya, Masaki
Oxidation of Metals, 92(5-6), p.439 - 455, 2019/12
Times Cited Count：0 Percentile：100(Metallurgy & Metallurgical Engineering)Futemma, Akira; Sanada, Yukihisa; Komiya, Tomokazu; Iwai, Takeyuki*; Seguchi, Eisaku*; Matsunaga, Yuki*; Kawabata, Tomoki*; Haginoya, Masashi*; Hiraga, Shogo*; Sato, Kazuhiko*; et al.
JAEA-Technology 2019-017, 95 Pages, 2019/11
JAEA-Technology-2019-017.pdf:12.09MB
By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the Great East Japan Earthquake and the following tsunami on March 11, 2011, a large amount of radioactive material was released from the FDNPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. We have carried out the background radiation monitoring around the nuclear power stations of the whole country to apply the airborne radiation monitoring technique that has been cultivated in the aerial monitoring around FDNPS against nuclear emergency response. The results of monitoring around Shimane and Hamaoka Nuclear Power Stations in the fiscal 2018 were summarized in this report. In addition, technical issues were described.
Nuclear Safety Research Center, Sector of Nuclear Safety Research and Emergency Preparedness
JAEA-Review 2019-015, 147 Pages, 2019/11
JAEA-Review-2019-015.pdf:7.77MB
Nuclear Safety Research Center (NSRC), Sector of Nuclear Safety Research and Emergency Preparedness, Japan Atomic Energy Agency (JAEA) is conducting technical support to nuclear safety regulation and safety research based on the Mid-Long Term Target determined by Japanese government. This report summarizes the research structure of NSRC and the cooperative research activities with domestic and international organizations as well as the nuclear safety research activities and results in JFY 2018 on the nine research fields in NSRC; (1) severe accident analysis, (2) radiation risk analysis, (3) safety of nuclear fuels in light water reactors (LWRs), (4) thermohydraulic behavior under severe accident in LWRs, (5) materials degradation and structural integrity, (6) safety of nuclear fuel cycle facilities, (7) safety management on criticality, (8) nuclear safeguards, and (9) safety of radioactive waste management.
Udagawa, Yutaka; Sugiyama, Tomoyuki; Amaya, Masaki
Journal of Nuclear Science and Technology, 56(11-12), p.1063 - 1072, 2019/11
no abstracts in English
Nuclear Emergency Assistance and Training Center
JAEA-Review 2019-013, 81 Pages, 2019/10
JAEA-Review-2019-013.pdf:5.53MB
The Japan Atomic Energy Agency (JAEA) is one of the designated public institutions. JAEA has responsibilities of providing technical assistances to the Japanese and local governments in case of nuclear or radiological emergencies based on these Acts. In order to fulfill the assistances, the JAEA has prepared the Nuclear Emergency Support Measures Regulation, Disaster Prevention Work Plan and Civil Protection Work Plan. The Nuclear Emergency Assistance and Training Center (NEAT) is the main center of the technical assistance in case of emergency, and dispatches experts, supplies equipment and gives them technical advice and information. In normal time, the NEAT provides the exercises and training courses concerning the nuclear preparedness and response to emergency responders. This report introduces the results of activities in Japanese Fiscal Year 2018, conducted by NEAT in accordance with the third medium and long-term plan from Japanese Fiscal Year 2015 to 2021.
Negyesi, M.; Amaya, Masaki
Journal of Nuclear Materials, 524, p.263 - 277, 2019/10
Times Cited Count：1 Percentile：22.81(Materials Science, Multidisciplinary)Miwa, Kazuji; Takeda, Seiji; Iimoto, Takeshi*
Radiation Protection Dosimetry, 184(3-4), p.372 - 375, 2019/10
The Ministry of the Environment has indicated the policy of recycling the contaminated soil generated by decontamination activity after the Fukushima accident. By recycling to coastal reclamation which is one of effective recycling application, dissolved radiocesium and absorbed radiocesium on soil particles will flow out to the ocean by construction, therefore evaluating radiocesium transition in ocean considering the both types of radiocesium is important for safety assessment. In this study, the radiocesium outflow during constructing and after constructing is modeled, and radiocesium transition in ocean is evaluated by Sediment model suggested in OECD/NEA. The adaptability of sediment model is confirmed by reproducing evaluation of the coastal area of Fukushima. We incorporate the sediment model to PASCLR2 code system to evaluate the doses from radiocesium in ocean.
Hata, Kuniki; Inoue, Hiroyuki*
Journal of Nuclear Science and Technology, 56(9-10), p.842 - 850, 2019/09
Times Cited Count：0 Percentile：100(Nuclear Science & Technology)To investigate the effect of dissolved species from steels on the radiolysis processes of Cl
, radiolysis simulations of solutions containing both Cl and Fe
were carried out. The results showed that the generation of radiolytic products (H
O, O and H) increased mainly by the addition of Fe, and a drop in the pH was caused by the hydrolysis of Fe
. This pH drop enhanced the reactivity of Cl with 
OH, which induced additional generation of HO and O. These results show that low concentrations of Cl (1 10
mol/dm
= 35ppm) in the presence of Fe could influence the generation of HO and O during water radiolysis. However, it is considered that these effects of Fe and low concentration of Cl on water radiolysis are less important for corrosion of steels due to the low concentrations of HO and O generated. The other process, such as dissolution of iron enhanced by FeOOH, might predominantly induce corrosion under the conditions of solutions with low concentrations of HO and O.
Nagaya, Yasunobu; Ueki, Taro; Tonoike, Kotaro
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09
A new Monte Carlo solver Solomon has been developed for the application to fuel-debris systems. It is designed not only for usual criticality safety analysis but also for criticality calculations of damaged reactor core including fuel debris. This paper describes the current status of Solomon and demonstrates the applications of the randomized Weierstrass function (RWF) model and the RWF model superimposed voxel geometry.
Izawa, Kazuhiko; Ishii, Junichi; Okubo, Takuya; Ogawa, Kazuhiko; Tonoike, Kotaro
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 9 Pages, 2019/09
Japan Atomic Energy Agency, JAEA, is conducting the renewal program of the heterogeneous water moderated critical assembly STACY (Static Experiment Critical Facility) in order to verify the criticality calculation considering fuel debris which have been produced in the accident of Fukushima Daiichi Nuclear Power Station. The first criticality of the new STACY is scheduled at the beginning of 2021. After the first criticality, it is necessary to perform a series of critical experiments with a series of basic experimental core in order to gain a proficiency of operators and grasp the uncertainty that accompanies the result of critical experiments in STACY. Prior to the construction of the new STACY, a series of neutronic calculation was carried out for licensing and planning first series of critical experiment. In this paper, possible core configuration of the basic experimental core and their limitations are discussed and presented.
Watanabe, Tomoaki; Okubo, Kiyoshi*; Araki, Shohei; Tonoike, Kotaro
Proceedings of 11th International Conference on Nuclear Criticality Safety (ICNC 2019) (Internet), 8 Pages, 2019/09
