Session: CS-10-01 Recent Developments in Japanese Codes and Standards

Paper Number: 61893

Start Time: Tuesday, July 13, 2021, 05:00 PM

61893 - Evaluation of Brittle Crack Arrest Toughness for Highly-Irradiated Reactor Pressure Vessel Steels 

Based on the recent revision of Japanese code, JEAC 4206-2016, which prescribes verification method of fracture toughness for in-service reactor pressure vessel (RPV) enabling to consider the crack arrest, we evaluate the crack arrest toughness for highly-irradiated RPV steel. Firstly, we confirmed the correlation between the reference temperature, T_KIa, of crack arrest toughness, K_Ia, and the temperature corresponding to a fixed arrest load, equal to 4 kN, T_Fa4kN, obtained from Charpy impact test for various RPV steels, because it is difficult to obtain K_Ia for irradiated materials directly. To estimate the K_Ia for highly-irradiated RPV steels, instrumented Charpy impact tests were carried out for several A533B steels irradiated up to 1.3x10²⁰ n/cm² (E > 1 MeV), and T_KIa for the irradiated materials were determined on the basis of the correlation between T_KIa and T_Fa4kN. Ductile-to-brittle transition temperatures at 41 J, T_41J, and its shift, ΔT_41J, due to irradiation were also determined by Charpy impact tests. Comparing T_KIa shift, ΔT_KIa, with ΔT_41J, we confirmed that ΔT_KIa was relatively lower than ΔT_41J for all tested materials. In JEAC 4206-2016, K_Ia curve can be described using the reference temperature shift for nil-ductile transition as ΔRT_NDT = ΔT_41J instead of ΔT_KIa. The results of this study showed that the K_Ia curve based on ΔT_41J is more conservative than K_Ia curve obtained using ΔT_KIa.

Presenting Author: Keiko Iwata Japan Atomic Energy Agency

Authors:

Keiko Iwata Japan Atomic Energy Agency
Kuniki Hata Japan Atomic Energy Agency
Tohru Tobita Japan Atomic Energy Agency
Takatoshi Hirota Mitsubishi Heavy Intustries, Ltd.
Hisashi Takamizawa Japan Atomic Energy Agency
Yasuhiro Chimi Japan Atomic Energy Agency
Yutaka Nishiyama Japan Atomic Energy Agency