Effect of grain refinement on cracks occurring in SUS304L stainless steel under nuclear reactor operating conditions

Hirota, Noriaki; Takeda, Ryoma; Ide, Hiroshi; Tsuchiya, Kunihiko; Kobayashi, Yoshinao*

Nuclear Materials and Energy (Internet), 45, p.102009_1 - 402009_10, 2025/12

https://doi.org/10.1016/j.nme.2025.102009

Using SUS304L stainless steel, which is employed in reactor structural components, the effects of grain refinement on stress corrosion cracking occurring under nuclear reactor operating conditions were investigated. As a result, after conducting slow strain rate testing (SSRT) in air and nuclear reactor operating environments, a comparison of the tensile properties of SUS304L with the same grain size revealed that elongation significantly decreased with increasing grain size under nuclear reactor operating conditions. In SSRT conducted in air, the -value obtained from the Hall-Petch relationship was lower than the conventional values. Observations showed the absence of cracks on SUS304L with 0.59 and 1.52 m grains; however, SUS304L with larger grains exhibited rougher fracture surfaces and side cracks. Thin oxide films were formed on SUS304L with 0.59 m and 1.52 m grains, while SUS304L with coarse grains of 28.4 m or larger enabled the formation of oxide films with over 2 m thickness. CrO films were formed on SUS304L with 0.59 m, 1.52 m, and 28.4 m, while CrO and Fe based oxides were formed on SUS304L with 39.5 m and 68.6 m. Crystal orientation analysis revealed linear surface layers without cracks in the -phase for SUS304L with 0.59 m and 1.52 m. In materials with Larger grain sizes, surface irregularities and cracks were observed in the -phase. In fine-grained SUS304L, lattice diffusion caused uniform O diffusion in the -phase, resulting in the formation of a thin CrO layer that suppressed cracks. In coarse-grained SUS304L, grain boundary diffusion caused Fe oxide formation at the grain boundaries, weakening them, and supersaturated O led to the formation of thick films comprising CrO and Fe-based oxides, resulting in peeling and cracking.

Consideration on roles and relationship between observations/measurements and model predictions for environmental consequence assessments for nuclear facilities

Togawa, Orihiko; Okura, Takehisa; Kimura, Masanori

JAEA-Review 2022-049, 76 Pages, 2023/01

JAEA-Review-2022-049.pdf:3.74MB

Before construction and after operation of nuclear facilities, environmental consequence assessments are conducted for normal operation and an emergency. These assessments mainly aim at confirming safety for the public around the facilities and producing relief for them. Environmental consequence assessments are carried out using observations/ measurements by environmental monitoring and/or model predictions by calculation models, sometimes using either of which and at other times using both them, according to the situations and necessities. First, this report investigates methods, roles, merits/demerits and relationship between observations/measurements and model predictions which are used for environmental consequence assessments of nuclear facilities, especially holding up a spent nuclear fuel reprocessing plant at Rokkasho, Aomori as an example. Next, it explains representative examples of utilization of data on observations/measurements and results on model predictions, and considers points of attention at using them. Finally, the report describes future direction, for example, improvements of observations/measurements and model predictions, and fusion of both them.

Finding evolutionary relations beyond superfamilies; Fold-based superfamilies

Matsuda, Keiko*; Nishioka, Takaaki*; Kinoshita, Kengo*; Kawabata, Takeshi*; Go, Nobuhiro

Protein Science, 12(10), p.2239 - 2251, 2003/10

https://doi.org/10.1110/ps.0383603

no abstracts in English

Simulation of a marine nuclear reactor

Kusunoki, Tsuyoshi; Kyoya, Masahiko; ;

Nuclear Technology, 109, p.275 - 285, 1995/02

https://doi.org/10.13182/NT95-A35060

no abstracts in English

Performance evaluation of nuclear ship engineering simulation system

Kyoya, Masahiko; ; Kusunoki, Tsuyoshi; ; Takahashi, Teruo*

JAERI-M 94-079, 116 Pages, 1994/06

JAERI-M-94-079.pdf:3.19MB

no abstracts in English

Development of Nuclear Ship Engineering Simulation System, NESSY

Kusunoki, Tsuyoshi; Kyoya, Masahiko; Takahashi, Teruo*; ; ;

JAERI-M 93-223, 176 Pages, 1993/11

JAERI-M-93-223.pdf:4.18MB

no abstracts in English

Control-rod interference effects observed during reactor physics experiments with nuclear ship MUTSU

; Miyoshi, Yoshinori; ; ;

Journal of Nuclear Science and Technology, 30(5), p.465 - 476, 1993/05

https://doi.org/10.3327/jnst.30.465

no abstracts in English

Outline of reactor physics tests conducted during the power-up tests in the nuclear ship Mutsu

; Miyoshi, Yoshinori; ;

JAERI-M 92-172, 62 Pages, 1992/11

JAERI-M-92-172.pdf:2.01MB

no abstracts in English

CASKETSS-2: A Computer code system for thermal and structural analysis of nuclear fuel shipping casks, Version 2

JAERI-M 91-129, 347 Pages, 1991/08

JAERI-M-91-129.pdf:6.82MB

no abstracts in English

Development of simplified computer codes for impact analysis of radioactive materials transport casks, 1st report; Computer code CRUSH for impact analysis of casks with shock absorbers

;

Nihon Genshiryoku Gakkai-Shi, 33(4), p.381 - 390, 1991/04

https://doi.org/10.3327/jaesj.33.381

no abstracts in English