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Yoshida, Kenta*; Toyama, Takeshi*; Inoue, Koji*; Nagai, Yasuyoshi*; Shimodaira, Masaki
Materia, 62(3), p.154 - 158, 2023/03
no abstracts in English
Takamizawa, Hisashi; Hata, Kuniki; Nishiyama, Yutaka; Toyama, Takeshi*; Nagai, Yasuyoshi*
Journal of Nuclear Materials, 556, p.153203_1 - 153203_10, 2021/12
Times Cited Count：3 Percentile：31.78(Materials Science, Multidisciplinary)Solute clusters (SCs) formed in pressurized water reactor surveillance test specimens neutron-irradiated to a fluence of 1 
10
n/cm
were analyzed via atom probe tomography to understand the effect of silicon on solute clustering and irradiation embrittlement of reactor pressure vessel steels. In high-Cu bearing materials, Cu atoms were aggregated at the center of cluster surrounded by the Ni, Mn, and Si atoms like a core-shell structure. In low-Cu bearing materials, Ni, Mn, and Si atoms formed cluster and these solutes were not comprised core-shell structure in SCs. While the number of Cu atoms in clusters was decreased with decreasing nominal Cu content, the number of Si atoms had clearly increased. The cluster radius (
) and number density (
) decreased and increased, respectively, with increasing nominal Si content. The shift in the reference temperature for nil-ductility transition (
RT
) showed a good correlation with the square root of volume fraction (
) multiplied by r (
). This suggested that the dislocation cutting through the particles mechanism dominates the precipitation hardening responsible for irradiation embrittlement. The negative relation between the nominal Si content and RT indicated that increasing of nominal Si content reduces the degree of embrittlement.
Takamizawa, Hisashi; Nishiyama, Yutaka
Journal of Pressure Vessel Technology, 143(5), p.051502_1 - 051502_8, 2021/10
Times Cited Count：3 Percentile：30.36(Engineering, Mechanical)no abstracts in English
Takamizawa, Hisashi; Nishiyama, Yutaka; Hirano, Takashi*
Proceedings of ASME 2020 Pressure Vessels and Piping Conference (PVP 2020) (Internet), 7 Pages, 2020/08
no abstracts in English
Takamizawa, Hisashi; Katsuyama, Jinya; Ha, Yoosung; Tobita, Toru; Nishiyama, Yutaka; Onizawa, Kunio
Proceedings of 2019 ASME Pressure Vessels and Piping Conference (PVP 2019) (Internet), 8 Pages, 2019/07
no abstracts in English
Takamizawa, Hisashi; Ito, Hiroto; Nishiyama, Yutaka
Journal of Nuclear Materials, 479, p.533 - 541, 2016/10
Times Cited Count：6 Percentile：49.29(Materials Science, Multidisciplinary)To understand neutron irradiation embrittlement in high fluence regions, statistical analysis using the Bayesian nonparametric (BNP) method was performed for the Japanese surveillance and material test reactor irradiation database. The BNP method is essentially expressed as an infinite summation of normal distributions, with input data being subdivided into clusters with identical statistical parameters (such as mean and standard deviation) for each cluster to estimate shifts in ductile-to-brittle transition temperature (DBTT). Clusters typically depend on chemical compositions, irradiation conditions, and the irradiation embrittlement. Specific variables contributing to the irradiation embrittlement include the content of Cu, Ni, P, Si, and Mn in the pressure vessel, neutron flux, neutron fluence, and irradiation temperatures. It was found through numerous examinations that the measured shifts of DBTT correlated well with calculated ones. Data associated with the same materials were subdivided into the same clusters even if neutron fluences were significantly disparate among the results. This indicates that slowly developing or late-onset embrittlement mechanisms were not evident in the present study.
Suzuki, Masahide; Nishiyama, Yutaka
Kinzoku, 71(8), p.42 - 45, 2001/08
no abstracts in English
Ishii, Toshimitsu; Ooka, Norikazu; Niimi, Motoji; Kobayashi, Hideo*
Kinzoku, 71(8), p.20 - 24, 2001/08
no abstracts in English
; Ooka, Norikazu; ; Saito, Junichi; Hoshiya, Taiji; *; Kobayashi, Hideo*
JAERI-Conf 99-009, p.163 - 172, 1999/09
no abstracts in English
; Ooka, Norikazu; Kobayashi, Hideo*
Proc. of 2nd Japan-US Symp. on Advances in NDT, p.151 - 156, 1999/00
no abstracts in English
Tsuji, Hirokazu; *; Tsukada, Takashi; Nakajima, Hajime
JAERI-M 93-204, 24 Pages, 1993/10
no abstracts in English
Nakajima, Hajime; ; *
1989-Nen Johogaku Shimpojiumu Rombunshu, p.17 - 26, 1989/01
no abstracts in English
; ;
Tetsu To Hagane, 68(8), p.1040 - 1045, 1982/00
no abstracts in English
; ; ;
Tetsu To Hagane, 61(8), p.1032 - 1039, 1982/00
no abstracts in English
fracture toughness of nuclear reactor pressure vessel steels by three-point bend specimens; ;
Tetsu To Hagane, 64(7), p.877 - 890, 1978/07
no abstracts in English
; ;
Yosetsu Gakkai-Shi, 38(6), p.608 - 614, 1969/00
no abstracts in English
Kawasaki, Masayuki; *
Genshiryoku Kogyo, 14(9), p.9 - 30, 1968/00
no abstracts in English
Otsu, Takuyo; Tobita, Toru; Fuse, Masaharu; Yamaki, Kenichi; Terakado, Hiroshi; Nishiyama, Yutaka
no journal, ,
no abstracts in English
Tobita, Toru; Otsu, Takuyo; Nishiyama, Yutaka
no journal, ,
Fracture toughness of the neutron irradiated reactor pressure vessel steel up to a fluence of 110 n/cm was performed using the 4 mm-thick miniature C(T) specimen. We evaluate fracture toughness scatter and a relation between the shifts of fracture toughness and Charpy DBTT.
Tobita, Toru; Otsu, Takuyo*; Takamizawa, Hisashi; Nishiyama, Yutaka
no journal, ,
When the reactor pressure vessel has been subjected to the pressurized thermal shock event, even if an non-ductile crack occurs from the postulated defect at the inner surface of the reactor pressure vessel, the crack may stop before penetrates the vessel wall. In this report, crack-arrest fracture toughness (K
) tests were performed on the three types of reactor pressure vessel steels with different mechanical properties. It was confirmed that the temperature dependency of K follows the Master Curve as well as static fracture toughness. In addition, we examined the correlation between the crack-arrest fracture toughness and crack arrest force of instrumentation Charpy test.
