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Yamashita, Shinichiro
Nihon Genshiryoku Gakkai-Shi ATOMO
, 65(4), p.233 - 237, 2023/04
In the wake of the accident at the Fukushima Daiichi Nuclear Power Plant (NPP) of TEPCO due to the Great East Japan Earthquake in 2011, interest in the early implementation of accident tolerant fuel (ATF) not only for many existing NPPs but also for future NPPs, which is expected to dramatically improve the safety of light water reactors, has increased globally, and research and development is currently underway in many countries around the world. In this article, an overview of domestic ATF technology development that has been carried out with the support of the Ministry of Economy, Trade and Industry since 2015, will be introduced.
Ukai, Shigeharu*; Yano, Yasuhide; Inoue, Toshihiko; Sowa, Takashi*
Materials Science & Engineering A, 812, p.141076_1 - 141076_11, 2021/04
Times Cited Count：12 Percentile：73.14(Nanoscience & Nanotechnology)FeCrAl oxide dispersion strengthened alloys are promising materials for accident tolerant fuels for light water reactors (LWRs). In these alloys, Al and Cr are key elements with important synergistic effects: enhancement of the formation of oxidation-resistant Al
O
phase by Cr addition and suppression of the formation of the embrittling Cr-rich 
' phase by Al addition. The solid-solution strengthening resulting from Al and Cr co-addition was investigated in this study. The solid-solution strengthening resulting from Al and Cr co-addition was investigated in this study. The Al and Cr contents were systematically varied from 9-16 at.% and 10-17 at.%, respectively, and tensile tests were conducted at 298 K, 573 K and 973 K in the as-annealed condition. The solid solution strengthening increased linearly, 20 MPa per 1 at.% Al and 5 MPa per 1 at.% Cr, at the typical LWR operational temperature of 573 K. The conventional Fleischer-Friedel and Labusch theories cannot explain this level of solid-solution strengthening. It was shown that Suzuki's double kink theory for screw dislocations reasonably predicts the solid solution strengthening by Al and Cr as well as the inverse dependency on the absolute temperature and linear dependency on the Al and Cr content.
Shirasu, Noriko; Saito, Hiroaki; Yamashita, Shinichiro; Nagase, Fumihisa
Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 8 Pages, 2017/09
Silicon carbide (SiC) is an attractive candidate of accident tolerant fuel (ATF) cladding material because of its high chemical stability, high radiation resistance and low neutron absorption. FEMAXI-ATF has been developed to analysis SiC cladding fuel behaviors. The thermal, mechanical and irradiation property models were implemented to FEMAXI-7, which is a fuel behavior analysis code being developed in JAEA. Fuel rod behavior analysis was performed under typical boiling water reactor (BWR) operating conditions with a model based on a 9
9 BWR fuel (Step III Type B), in which the cladding material was replaced from Zircaloy to SiC. The SiC cladding shows large swelling by irradiation. It increases the gap size and decreases cladding thermal conductivity. The mechanism of relaxation of stress is also different from the Zircaloy cladding. The experimental data for SiC materials are still insufficient to construct the models, especially for evaluating fracture behavior.
Yamashita, Shinichiro; Nagase, Fumihisa; Kurata, Masaki; Kaji, Yoshiyuki
Proceedings of Annual Topical Meeting on LWR Fuels with Enhanced Safety and Performance (TopFuel 2016) (USB Flash Drive), p.21 - 30, 2016/09
Fuel rod, channel box, and control rod designed with new materials and concepts have been developed in Japan for increasing accident tolerance of LWRs. In order to efficiently and properly implement the accident tolerant fuels (ATFs) and the other components, it is necessary not only to accumulate fundamental and practical data but also to consider technology readiness, recognize knowledge gaps, and establish strategy for design and fabrication. The Japan Atomic Energy Agency (JAEA) has established the above "technical basis" and drafted a research plan towards implementation of the ATFs and components as a program sponsored and organized by the Ministry of Economy, Trade and Industry (METI). It is useful to take advantage of the experiences in commercial uses of zirconium-base alloys in LWRs and, therefore, JAEA has conducted this METI project in cooperation with power plant providers, fuel venders, research institutes and universities who have been involved in the development of the ATF materials. The present paper describes the main results of the project conducted to establish the technical basis of the ATFs and components.
and SiC in LWR conditionsShirasu, Noriko; Kurata, Masaki
no journal, ,
After Fukushima Daiichi nuclear accident in 2011, enhancing the accident tolerance of light water reactor fuels became a very important issue and currently the development of accident-tolerant fuel (ATF) are in progress. SiC is an attractive candidate of ATF cladding material because of its high chemical stability, high radiation resistance and low neutron absorption. SiC reacts much less than Zircaloy with steam, the generation of heat and hydrogen gas would be extremely suppressed. Thermodynamic evaluation on chemical interactions between UO and SiC were performed on various possible conditions of oxygen potential and temperature in severe accident. SiC is converted to SiO by reaction with O. SiC is also converted to SiO by reaction with HO. However, the fraction of the sub-reaction for forming SiO increases than in the case of reaction with O when comparing the results at the same temperatures and the same oxygen potentials.
Yamashita, Shinichiro
no journal, ,
In this oral presentation, the result of "Development of Technical Basis for Introducing Advanced Fuels Contributing to Safety Improvement of Current Light Water Reactors" carried out under the Project on Development of Technical Basis for Safety Improvement at Nuclear Power Plants by Ministry of Economy, Trade and Industry (METI) of Japan will be partially introduced. The gap between the present R&D status and the achievement of practical use in order to progress the R&D properly and efficiently will be talked together with related information of oversea research activities.
Nagase, Fumihisa
no journal, ,
JAEA conducts R&D to support the decommissioning at the Fukushima Daiichi NPS and to contribute improvement of the LWR safety in the frame of domestic and international collaborations as well as the own projects. The R&D mostly focuses on the phenomena in BWRs and covers various issues related to materials degradation in severe accidents. In parallel, JAEA has the research activity to establish technical basis for practical use of accident tolerant fuel (ATF) components in existing LWRs. The preliminary computer code analyses showed necessary material data and subjects to design the ATF components.
Takahashi, Katsuhito*; Sakamoto, Kan*; Otsuka, Teppei*; Ukai, Shigeharu*; Hirai, Mutsumi*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Takeuchi, Yutaka*; Kakiuchi, Kazuo*; Sato, Hisaki*; Shirasu, Noriko; Saito, Hiroaki; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Yamaji, Kazuya*; Kirimura, Kazuki*; Kosaka, Shinya*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Furumoto, Kenichiro*; Teshima, Hideyuki*; Watanabe, Seiichi*; Yamamoto, Teruhisa*; Shirasu, Noriko; Saito, Hiroaki; Yamashita, Shinichiro
no journal, ,
Mitsubishi Nuclear Fuel (MNF) plans to evaluate an influence of Silicon Carbide (SiC) composite cladding upon fuel rod behavior in current pressurized water reactors (PWR). In this presentation, the evaluation result of the applicability of fuel rod with SiC composite cladding for a conventional PWR will be reported. For the applicability evaluations of SiC composite to conventional PWR, both of analytical evaluations and out-of-pile tests for SiC composite were conducted. Analytical evaluations were performed by Mitsubishi's own fuel rod design code and the fuel rod behavior evaluation code developed by JAEA. These codes were modified to evaluate the behavior of the fuel rod with SiC composite cladding.
Watanabe, Seiichi*; Teshima, Hideyuki*; Furumoto, Kenichiro*; Katayama, Masaaki*; Yamashita, Shinichiro
no journal, ,
Due to its hydrogen-generation rate and reaction heat being lower than those of conventional Zircaloy, SiC is expected to be an appropriate material for accident-tolerant fuels. There are, however, only a few knowledge on behavior of SiC composite cladding under design basis accident condition (DBA). In this study test apparatus were developed for evaluation of behavior of SiC composite cladding and the mock-up tests using SiC cladding were performed under the condition simulated DBA.
Yamakoshi, Yoshinori*; Kirimura, Kazuki*; Kosaka, Shinya*; Yamashita, Shinichiro
no journal, ,
Accident tolerant of SiC under severe accident condition was evaluated on the assumption that SiC fuel cladding was implemented to existing PWR plant.
Yuzawa, Sho*; Yabuuchi, Kiyohiro*; Kimura, Akihiko*; Sakamoto, Kan*; Hirai, Mutsumi*; Yamashita, Shinichiro
no journal, ,
Oxide dispersion strengthened steel with high Cr and Al concentration in chemical composition (FeCrAl-ODS steel) has been proposed as a promising candidate for the accident tolerant fuel cladding of light water reactors (LWRs) because of their excellent oxidation and corrosion resistance under high temperature water and steam environments. Neither there are no sufficient knowledge on welding technology of FeCrAl-ODS nor it is known that aluminum addition remarkably degrades the weldability of the ODS steel. In this study, electron beam (EB) welding and tungsten inert gas (TIG) welding were applied to the SUS430 endcap welding to cladding tube made of FeCrAl-ODS steel and performed the bonding strength and corresponding damage structure evaluations at the bonding part.
Horie, Hideki*; Takeuchi, Yutaka*; Kakiuchi, Kazuo*; Sato, Hisaki*; Shirasu, Noriko; Saito, Hiroaki; Yamashita, Shinichiro; Fukahori, Tokio
no journal, ,
The problem in the accident tolerance fuel development was considered in comparison the fuel behavior of SiC/SiC composite cladding tube with current Zry cladding tube. In this study, Reactivity Initiated Accident (RIA) was evaluated using the plant excess security analysis code TRACTTM and the fuel performance code FEMAXI.
Yamashita, Shinichiro
no journal, ,
In order to increase accident tolerance of light water reactors (LWRs), fuel rod, channel box and control rod with new materials and concepts have been considered and developed in Japan. Since 2015, the Japan Atomic Energy Agency (JAEA) has conducted and coordinated the Japanese R&D program of accident tolerant fuel (ATF) for establishing technical basis of ATF under a program sponsored and organized by the Ministry of Economy, Trade and Industry (METI). This program has been carried out in cooperation with power plant providers, fuel venders and universities because it is efficient and proper to take advantage of the experiences in R&D, practical design, and evaluations of fuels and cores of commercial LWRs.
Ishibashi, Ryo*; Ikegawa, Tomohiko*; Tanabe, Shigetada*; Yamashita, Shinichiro; Fukahori, Tokio
no journal, ,
For the purpose of improving corrosion resistance of silicon carbide (SiC) in boiling water reactor (BWR) environments, corrosion resistant coatings to SiC substrate were evaluated. Due to its lower hydrogen generation rate and lower reaction heat in comparison with a conventional zircaloy, SiC is expected to be a proper material for accident tolerant fuel. On the other hand, there are still a lot of critical issues left for the practical application of SiC fuel cladding and fuel channel box, one of which is hydrothermal corrosion. In this study, corrosion behavior of candidate coatings to SiC substrate and joint portion were evaluated in unirradiated high purity water environments.
Ambai, Hiromu; Takahatake, Yoko; Sano, Yuichi; Takeuchi, Masayuki; Koizumi, Kenji; Yamashita, Shinichiro; Sakamoto, Kan*
no journal, ,
A FeCrAl-ODS steel has been developed for the accident tolerant fuel cladding of light water reactors in Japanese projects. Spent fuel are reprocessed in Japan, namely spent fuel pins are chopped and immersed into a hot nitric acid solution to leach out the fuel. Behavior of the corrosion products from fuel cladding should be evaluated to estimate the influence of those on the reprocessing process. In this study, effect of nitric acid concentration on corrosion behavior of Fe-12Cr-6Al based oxide dispersion strengthened steels was evaluated.
Yamashita, Shinichiro; Nemoto, Yoshiyuki; Ioka, Ikuo; Kawanishi, Tomohiro; Kurata, Masaki; Kaji, Yoshiyuki; Fukahori, Tokio
no journal, ,
After the 2011 Great East Japan Earthquake and Tsunami, and the events that followed at the Fukushima Daiichi Nuclear Power Station (1F), global interest has expanded in exploring fuels with enhanced performance during such rare events, with accident-tolerant fuel (ATF) development programs starting in many countries. In Japan, several ATF programs have been launched for feasibility study, development of manufacturing technology, and establishment of technical basis since the 1F accident. ATF candidate materials considered in Japan are silicon carbide (SiC) composite and FeCrAl steel strengthened by dispersion of fine oxide particles (FeCrAl-ODS). SiC composite is very attractive material because of its lower hydrogen generation rate and lower reaction heat in comparison with conventional Zirconium (Zr) alloys. Therefore, practical uses for a fuel cladding of pressurized water reactor (PWR) and for the fuel cladding, channel box of boiling water reactor (BWR) are expected. On the other hand, FeCrAl-ODS steel is a promising material and is considered to apply to the fuel cladding of BWR.
Yamashita, Shinichiro; Shirasu, Noriko; Saito, Hiroaki
no journal, ,
The FEMAXI-ATF code has been developed to analyze the SiC-cladding-fuel behaviors as an extended version of the LWR fuel-analysis code FEMAXI-7. The analysis using the FEMAXI-ATF code indicated that the SiC cladding shows large swelling by irradiation and it causes the decrease of cladding thermal conductivity and the gap conductance, and consequently increase of the fuel temperature. Furthermore, the mechanical integrity for SiC cladding and influence of pellet-cladding mechanical interaction (PCMI) were evaluated.
