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Tasaki, Yudai; Udagawa, Yutaka
JAEA-Data/Code 2024-012, 76 Pages, 2024/12
JAEA-Data-Code-2024-012.pdf:9.25MB
Japan Atomic Energy Agency (JAEA) has been developing a fuel performance code, FEMAXI, to evaluate the behavior of LWR fuels under normal operation and transient conditions. In March 2019, FEMAXI-8, the first systematically validated and performance evaluated code, was released. Since then, the code has undergone various improvements. In parallel, since the 2000s, JAEA has been developing the RANNS module as a branch for design basis accident (DBA) analysis, with a particular emphasis on computational stability, so that fuel behavior can be tracked even for very steep transients, in this case mainly reactivity-initiated accidents (RIAs). The specific models include boiling heat transfer, fission gas release by grain boundary failure, and cladding failure determination based on fracture mechanics parameters, which are essential for predicting such transient behavior. In this report, prior to the release of RANNS, we present a description of the models for accident behavior analysis, the relationship with FEMAXI-8 in terms of the design and structure of the program, and the results of a large-scale validation using the extensive database of RIA experiments conducted and accumulated by JAEA, to evaluate the overall RIA analysis performance. The code will be made available to users as a packaged FEMAXI/RANNS, enabling them to analyze fuel behavior under various conditions. The model parameter sets determined through the above validation analyses are also presented in this report, and by referring to them, the analysis can be easily performed with almost no change in usability from the previously released FEMAXI-8.
Tasaki, Yudai; Narukawa, Takafumi; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 61(10), p.1349 - 1359, 2024/10
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Li, F.; Mihara, Takeshi; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 61(9), p.1265 - 1275, 2024/09
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Li, F.; Narukawa, Takafumi; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 61(8), p.1036 - 1047, 2024/08
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Mohamad, A. B.; Udagawa, Yutaka
Nuclear Technology, 210(2), p.245 - 260, 2024/02
Times Cited Count：2 Percentile：35.82(Nuclear Science & Technology)Taniguchi, Yoshinori; Mihara, Takeshi; Kakiuchi, Kazuo; Udagawa, Yutaka
Annals of Nuclear Energy, 195, p.110144_1 - 110144_11, 2024/01
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Narukawa, Takafumi; Kondo, Keietsu; Fujimura, Yuki; Kakiuchi, Kazuo; Udagawa, Yutaka; Nemoto, Yoshiyuki
Journal of Nuclear Materials, 587, p.154736_1 - 154736_8, 2023/12
Times Cited Count：1 Percentile：35.82(Materials Science, Multidisciplinary)Narukawa, Takafumi; Hamaguchi, Shusuke*; Takata, Takashi*; Udagawa, Yutaka
Nuclear Engineering and Design, 411, p.112443_1 - 112443_12, 2023/09
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Narukawa, Takafumi; Kondo, Keietsu; Fujimura, Yuki; Kakiuchi, Kazuo; Udagawa, Yutaka; Nemoto, Yoshiyuki
Journal of Nuclear Materials, 582, p.154467_1 - 154467_12, 2023/08
Times Cited Count：3 Percentile：75.12(Materials Science, Multidisciplinary)
17 type PWR fuel cladding tube under LOCA-simulated burst conditionsFurumoto, Kenichiro; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 60(5), p.500 - 511, 2023/05
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)
fuel with additives under reactivity-initiated accident conditionsMihara, Takeshi; Kakiuchi, Kazuo; Taniguchi, Yoshinori; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 60(5), p.512 - 525, 2023/05
Times Cited Count：1 Percentile：18.18(Nuclear Science & Technology)Kakiuchi, Kazuo; Amaya, Masaki; Udagawa, Yutaka
Journal of Nuclear Materials, 573, p.154110_1 - 154110_7, 2023/01
Times Cited Count：1 Percentile：18.18(Materials Science, Multidisciplinary)Li, F.; Mihara, Takeshi; Udagawa, Yutaka
Journal of Nuclear Science and Technology, 59(12), p.1455 - 1464, 2022/12
Times Cited Count：2 Percentile：35.75(Nuclear Science & Technology)Narukawa, Takafumi; Hamaguchi, Shusuke*; Takata, Takashi*; Udagawa, Yutaka
Proceedings of Asian Symposium on Risk Assessment and Management 2022 (ASRAM 2022) (Internet), 11 Pages, 2022/12
Kakiuchi, Kazuo; Yamauchi, Akihiro*; Amaya, Masaki; Udagawa, Yutaka; Kitano, Koji*
Proceedings of TopFuel 2022 (Internet), p.409 - 418, 2022/10
Kakiuchi, Kazuo; Udagawa, Yutaka; Yamauchi, Akihiro*
JAEA-Research 2022-001, 21 Pages, 2022/06
JAEA-Research-2022-001.pdf:1.84MB
The primary cause of cladding embrittlement during loss-of-cool ant accident (LOCA) is the increase in oxygen concentration in the metallic layer and associated microstructural change due to oxidation. In the case of cladding high temperature rupture, inner surface oxidation by the steam ingress and the consequent increase in hydrogen partial pressure result in hydrogen absorption (secondary hydriding) localized in the axial direction at the distance apart from the rupture opening as is well known from preceding studies. In order to understand the effect of cladding microstructural changes on mechanical property of a fuel rod under LOCA conditions in a more precise and quantitative manner, the nanoindentation method has been applied to evaluation of mechanical properties of a cladding specimen after a LOCA simulated test; results for two samples taken from the rupture opening part and secondary hydriding part were compared with each other. The fraction of plastic work during the indentation was evaluated from the load-displacement curve in addition to hardness and Young's modulus. The plastic work fraction at the secondary hydriding part was found to be clearly lower than that at the rupture opening part and rather close to that in the ZrO and 
-Zr(O) layers, suggesting the significant ductility reduction of the secondary hydriding part despite its relatively low oxygen concentration.
Kakiuchi, Kazuo; Amaya, Masaki; Udagawa, Yutaka
Annals of Nuclear Energy, 171, p.109004_1 - 109004_9, 2022/06
Times Cited Count：5 Percentile：69.23(Nuclear Science & Technology)Tasaki, Yudai; Udagawa, Yutaka; Amaya, Masaki
Journal of Nuclear Science and Technology, 59(3), p.382 - 394, 2022/03
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)Taniguchi, Yoshinori; Mihara, Takeshi; Udagawa, Yutaka
Proceedings of TopFuel 2021 (Internet), 10 Pages, 2021/10
Mihara, Takeshi; Kakiuchi, Kazuo; Taniguchi, Yoshinori; Udagawa, Yutaka
Proceedings of TopFuel 2021 (Internet), 10 Pages, 2021/10
