Engineering formulation of the irradiation growth behavior of zirconium-based alloys for light water reactors

Kakiuchi, Kazuo; Amaya, Masaki; Udagawa, Yutaka

Journal of Nuclear Materials, 573, p.154110_1 - 154110_7, 2023/01

https://doi.org/10.1016/j.jnucmat.2022.154110

Hierarchical Bayes model to quantify fracture limit uncertainty of high-burnup advanced fuel cladding tubes under LOCA conditions

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

Mechanical property evaluation of Zircaloy cladding tube after LOCA-simulated experiment using nanoindentation method (Joint research)

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.

Evaluation of anisotropic elastic and plastic parameters of Zircaloy-4 fuel cladding from biaxial stress test data and their application to a fracture mechanics analysis

Li, F.; Mihara, Takeshi; Udagawa, Yutaka

Journal of Nuclear Science and Technology, 10 Pages, 2022/04

https://doi.org/10.1080/00223131.2022.2062474

Behavior of high-burnup BWR UO fuel with additives under reactivity-initiated accident conditions

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

Journal of Nuclear Science and Technology, 14 Pages, 2022/00

https://doi.org/10.1080/00223131.2022.2122616

Follow-up experimental study on causes of the low-enthalpy failure observed in the reactivity-initiated-accident-simulated test on LWR additive fuels

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

Proceedings of TopFuel 2021 (Internet), 10 Pages, 2021/10

Simulation of the effect of radially oriented hydride precipitates on failure limit of high-burnup BWR fuel cladding under PCMI loading

Taniguchi, Yoshinori; Mihara, Takeshi; Udagawa, Yutaka

Proceedings of TopFuel 2021 (Internet), 10 Pages, 2021/10

Improvement of intragranular fission gas behavior model for fuel performance code FEMAXI-8

Udagawa, Yutaka; Tasaki, Yudai

JAEA-Data/Code 2021-007, 56 Pages, 2021/07

JAEA-Data-Code-2021-007.pdf:5.05MB

Japan Atomic Energy Agency (JAEA) has released FEMAXI-8 in 2019 as the latest version of the fuel performance code FEMAXI, which has been developed to analyze thermal and mechanical behaviors of a single fuel rod in mainly normal operation conditions and anticipated transient conditions. This report summarizes a newly developed model to analyze intragranular fission gas behaviors considering size distribution of gas bubbles and their dynamics. While the intragranular fission gas behavior models implemented in the previous FEMAXI versions have supported only treating single bubble size for a given fuel element, the new model supports multiple gas groups according to their size and treats their dynamic behaviors, making the code more versatile. The model was first implemented as a general module that takes arbitrary number of bubble groups and spatial mesh division for a given fuel grain system. An interface module to connect the model to FEMAXI-8 was then developed so that it works as a 2 bubble groups model, which is the minimum configuration of the multi-grouped model to be operated with FEMAXI-8 at the minimum calculation cost. FEMAXI-8 with the new intragranular model was subjected to a systematic validation calculation against 144 irradiation test cases and recommended values for model parameters were determined so that the code makes reasonable predictions in terms of fuel center temperature, fission gas release, etc. under steady-state and power ramp conditions.

Development and release of fuel performance code FEMAXI-8

Udagawa, Yutaka

Nihon Genshiryoku Gakkai-Shi ATOMO, 62(10), p.555 - 559, 2020/10

https://doi.org/10.3327/jaesjb.62.10_555

no abstracts in English

Effects of pre-crack depth and hydrogen absorption on the failure strain of Zircaloy-4 cladding tubes under biaxial strain conditions

Li, F.; Mihara, Takeshi; Udagawa, Yutaka; Amaya, Masaki

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 7 Pages, 2020/08

https://doi.org/10.1115/ICONE2020-16738