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Otsuka, Satoshi; Shizukawa, Yuta; Tanno, Takashi; Imagawa, Yuya; Hashidate, Ryuta; Yano, Yasuhide; Onizawa, Takashi; Kaito, Takeji; Onuma, Masato*; Mitsuhara, Masatoshi*; et al.
Journal of Nuclear Science and Technology, 60(3), p.288 - 298, 2023/03
Times Cited Count：4 Percentile：78.52(Nuclear Science & Technology)JAEA has been developing 9Cr-oxide dispersion strengthened (ODS) tempered martensitic steel(TMS) as a candidate material for the fuel cladding tubes of sodium-cooled fast reactors(SFRs). The reliable prediction of in-reactor creep-rupture strength is critical for implementing the 9Cr-ODS TMS cladding tube in the SFR. This study investigated the quantitative correlation between the creep properties of 9Cr-ODS TMS at 700 
C and the dispersions of nanosized oxides by analyzing the creep data and the material's nanostructure. The possibility of deriving a formula for estimating the in-reactor creep properties of 9Cr-ODS TMSs based on an analysis of the nanostructure of neutron-irradiated 9Cr-ODS TMSs was also discussed. The creep properties of 9Cr-ODS TMS at 700 C closely correlated with the dispersion of nanosized oxide particles. The correlation between creep-rupture lives and nanosized oxide particle dispersion was determined using existing creep models. The elucidation of correlation between the stress exponent of secondary creep rate and the nanostructure is essential to enhance future modeling reliability and formulation.
Ukai, Shigeharu*; Ono, Naoko*; Otsuka, Satoshi
Comprehensive Nuclear Materials, 2nd Edition, Vol.3, p.255 - 292, 2020/08
Fe-Cr-based oxide dispersion strengthened (ODS) steels have a strong potential for high burnup (long-life) and high-temperature applications typical for SFR fuel cladding. Current progress in the development of Fe-Cr-based ODS steel claddings is reviewed, including their relevant mechanical properties, e.g. tensile and creep rupture strengths in the hoop directions. In addition, this paper reviewed the current research status on corrosion resistant Fe-Cr-Al-based ODS steel claddings, which are greatly paid attention recently as the accident tolerant fuel claddings for the light water reactor (LWR) and also as the claddings of the lead fast reactors (LFR) utilizing Pb-Bi eutectic (LBE) coolant.
Otsuka, Satoshi; Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Tachi, Yoshiaki; Kaito, Takeji; Hashidate, Ryuta; Kato, Shoichi; Furukawa, Tomohiro; Ito, Chikara; et al.
2018 GIF Symposium Proceedings (Internet), p.305 - 314, 2020/05
Oxide Dispersion Strengthened (ODS) steel has been developed worldwide as a high-strength and radiation-tolerant steel used for advanced nuclear system. Japan Atomic Energy Agency (JAEA) has been developing ODS steel as the primary candidate material of Sodium cooled Fast Reactor (SFR) high burn-up fuel cladding tube. Application of high burn-up fuel to SFR core can contribute to improvement of economical performance of SFR in conjunction with volume and hazardousness reduction of radioactive waste. This paper described the current status and future prospects of ODS tempered martensitic steel development in JAEA for SFR fuel application.
Otsuka, Satoshi; Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Kato, Shoichi; Furukawa, Tomohiro; Kaito, Takeji
Journal of Nuclear Materials, 505, p.44 - 53, 2018/07
Times Cited Count：2 Percentile：20.93(Materials Science, Multidisciplinary)A calculation model was constructed to systematically study the effects of environmental conditions (i.e. Cr concentration in sodium, test temperature, axial temperature gradient of fuel pin, and sodium flow velocity) on Cr dissolution behavior. Chromium dissolution was largely influenced by small changes in Cr concentration (i.e. chemical potential of Cr) in liquid sodium in the model calculation. Chromium concentration in sodium coolant, therefore, should be recognized as a critical parameter for the prediction and management of Cr dissolution behavior in the sodium-cooled fast reactor (SFR) core. Because the fuel column length showed no impact on dissolution behavior in the model calculation, no significant downstream effects possibly take place in the SFR fuel cladding tube due to the much shorter length compared with sodium loops in the SFR plant and the large axial temperature gradient. The calculated profile of Cr concentration along the wall-thickness direction was consistent with that measured in BOR-60 irradiation test where Cr concentration in sodium bulk flow was set at 0.07 wt ppm in the calculation.
Ukai, Shigeharu*; Otsuka, Satoshi; Kaito, Takeji; de Carlan, Y.*; Ribis, J.*; Malaplate, J.*
Structural Materials for Generation IV Nuclear Reactors, p.357 - 414, 2017/00
Times Cited Count：71 Percentile：99.33(Energy & Fuels)Oxide dispersion strengthened (ODS) steels are the most promising candidate materials for fuel cladding of generation IV nuclear reactors. The progress and current status for development of ODS/FM(ferrite-martensite) steels conducted mainly in Japan and France are overviewed. The chemical compositions of ODS/FM steels are listed. Fabrication routes of cladding tube are mentioned for ferrite-type ODS steels using recrystallized process and martensite-type one using 
-
phase transformation. The optimized process is identical for both countries. Joining process between cladding and end-plug has been also developed by using the pressurized resistance upset welding method. The improvements brought by ODS/FM steels in high-temperature strength and irradiation resistance are verified.
Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Kaito, Takeji
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Tanno, Takashi; Oka, Hiroshi; Otsuka, Satoshi; Yano, Yasuhide; Kaito, Takeji
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Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Yano, Yasuhide; Uwaba, Tomoyuki; Kaito, Takeji
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no abstracts in English
Yamashita, Shinichiro; Kondo, Keietsu; Aoki, So; Hashimoto, Naoyuki*; Ukai, Shigeharu*; Sakamoto, Kan*; Hirai, Mutsumi*; Kimura, Akihiko*; Kusagaya, Kazuyuki*
no journal, ,
As the lesson learned from the accident at the Fukushima Daiichi Nuclear Power Station, it is commonly recognized that development of the advanced fuel and core components with enhanced accident tolerance and high reliability is quite important for increasing safety of the existing Light Water Reactors (LWRs). FeCrAl-ODS steel is one of prospective candidate materials with enhanced accident tolerance and needs to be accumulated properly and efficiently fundamental and practical data for core and plant design of nuclear reactor. In this study, hardness measurement and microstructural observation for ion-irradiated FeCrAl-ODS steel were conducted in order to evaluate irradiation property in advance toward a research reactor irradiation test. The results indicated that steep irradiation hardening occurred at the initial stage of irradiation and also that nucleation and growth of irradiation defect cluster occurred at the higher dose than the irradiation hardening occurred.
Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji
no journal, ,
Fe self-ion irradiation to ODS steels was conducted at 400C to evaluate the stability of oxide nano-dispersoids in the ODS steels and embrittlement behavior of higher Cr ODS steel under irradiation. Fe and He dual ion irradiation test at 470C was also conducted to evaluate the influence of He existence. The indentation hardness increased in early stage of the irradiation, and decreased over 150 dpa. But the hardness was higher than that as unirradiated, even if the dose reached 230 dpa. The Cr enrichment from 9Cr to 11Cr would not lead to extra irradiation hardening and/or irradiation embrittlement because the irradiation hardening behavior of 9Cr and 11Cr-ODS steels were almost same. The irradiation hardening due to Fe+He dual ions irradiation was negligible or comparatively small. Therefore it was considered that fine and dense voids formation enhanced by He existence was not significant.
Uwaba, Tomoyuki; Yano, Yasuhide; Otsuka, Satoshi; Naganuma, Masayuki; Tanno, Takashi; Oka, Hiroshi; Kato, Shoichi; Kaito, Takeji; Ukai, Shigeharu*; Kimura, Akihiko*; et al.
no journal, ,
no abstracts in English
Yano, Yasuhide; Kato, Shoichi; Otsuka, Satoshi; Uwaba, Tomoyuki; Sekio, Yoshihiro; Inoue, Toshihiko; Furukawa, Tomohiro; Kaito, Takeji; Ukai, Shigeharu*; Kimura, Akihiko*; et al.
no journal, ,
no abstracts in English
Oka, Hiroshi; Tanno, Takashi; Otsuka, Satoshi; Kaito, Takeji
no journal, ,
no abstracts in English
Kusagaya, Kazuyuki*; Takano, Sho*; Goto, Daisuke*; Sakamoto, Kan*; Hirai, Mutsumi*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Sowa, Takashi*; Ukai, Shigeharu*; Aghamiri, M.*; Shibata, Hironori*; Hayashi, Shigenari*; Ono, Naoko*; Sakamoto, Kan*; Hirai, Mutsumi*; Yamashita, Shinichiro
no journal, ,
no abstracts in English
Kimura, Akihiko*; Yuzawa, Sho*; Yabuuchi, Kiyohiro*; Sakamoto, Kan*; Hirai, Mutsumi*; Ukai, Shigeharu*; Yamashita, Shinichiro; Kusagaya, Kazuyuki*
no journal, ,
no abstracts in English
Takahashi, Katsuhito*; Sakamoto, Kan*; Otsuka, Teppei*; Ukai, Shigeharu*; Hirai, Mutsumi*; Yamashita, Shinichiro
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Tanno, Takashi; Yano, Yasuhide; Tsukada, Tatsuya*; Sakamoto, Kan*; Yamashita, Shinichiro
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no abstracts in English
Takano, Sho*; Goto, Daisuke*; Kusagaya, Kazuyuki*; Sakamoto, Kan*; Yamashita, Shinichiro
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For practical use of FeCrAl-ODS stainless steel, it is necessary to confirm that a design request in a reactor core is achieved even if the loss of neutron economy is caused by the big neutron absorption cross section. In previous study, the core design was established in the case of cladding thickness of 0.3 mm, water rod thickness of 0.3 mm and channel box thickness of 1.0 mm. In this report, the core property was evaluated when FeCrAl-ODS stainless steel and MOX fuel were applied.
