Analysis of fracture conditions of Cr-coated Zr alloy claddings under LOCA conditions calculated using FEMAXI fuel performance code

Luu, V. N.; Taniguchi, Yoshinori; Udagawa, Yutaka; Tasaki, Yudai; Katsuyama, Jinya

Annals of Nuclear Energy, 230, p.112114_1 - 112114_14, 2026/06

https://doi.org/10.1016/j.anucene.2026.112114

Generation of pressure pulse and water hammer triggered by high-burnup fuel failure under reactivity-initiated accident conditions

Mihara, Takeshi; Udagawa, Yutaka

Journal of Nuclear Science and Technology, 17 Pages, 2026/00

https://doi.org/10.1080/00223131.2025.2611410

Effect of rod internal gas state on FFRD behavior of high burnup fuel during LOCA conditions

Kakiuchi, Kazuo; Narukawa, Takafumi*; Udagawa, Yutaka; Katsuyama, Jinya; Mihara, Takeshi; Amaya, Masaki

Proceedings of TopFuel 2025; Nuclear Reactor Fuel Performance Conference (Internet), p.1440 - 1449, 2025/10

Extension of fuel performance code package FEMAXI; Development and validation of reactivity-initiated accident analysis module RANNS for light water reactor fuels

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.

Fission gas dynamics test; Development of reactivity-initiated-accident testing technique devoted to investigation of fission gas release kinetics

Mihara, Takeshi; Urano, Kenta; Udagawa, Yutaka

Proceedings of TopFuel 2024 (Internet), 9 Pages, 2024/10

The Effect of a cyclic bending load on the bending resistance of ballooned, ruptured, and oxidized Zircaloy-4 cladding

Li, F.; Narukawa, Takafumi; Udagawa, Yutaka

Journal of Nuclear Science and Technology, 61(8), p.1036 - 1047, 2024/08

https://doi.org/10.1080/00223131.2023.2293100

Uncertainty analysis of model selection based on information criterion; A Case study of a probability estimation model for fuel cladding tube fracture during LOCA

Narukawa, Takafumi; Udagawa, Yutaka

Transactions of the 27th International Conference on Structural Mechanics in Reactor Technology (SMiRT 27) (Internet), 10 Pages, 2024/03

High-temperature rupture failure of high-burnup LWR-MOX fuel under a reactivity-initiated accident condition

Taniguchi, Yoshinori; Mihara, Takeshi; Kakiuchi, Kazuo; Udagawa, Yutaka

Annals of Nuclear Energy, 195, p.110144_1 - 110144_11, 2024/01

https://doi.org/10.1016/j.anucene.2023.110144

Hierarchical Bayesian modeling to quantify fracture limit uncertainty of high-burnup advanced fuel cladding tubes under loss-of-coolant accident conditions

Narukawa, Takafumi; Hamaguchi, Shusuke*; Takata, Takashi*; Udagawa, Yutaka

Nuclear Engineering and Design, 411, p.112443_1 - 112443_12, 2023/09

https://doi.org/10.1016/j.nucengdes.2023.112443

Effects of azimuthal temperature distribution and rod internal gas energy on ballooning deformation and rupture opening formation of a 17 17 type PWR fuel cladding tube under LOCA-simulated burst conditions

Furumoto, Kenichiro; Udagawa, Yutaka

Journal of Nuclear Science and Technology, 60(5), p.500 - 511, 2023/05

https://doi.org/10.1080/00223131.2022.2116497