Evaluation of neutron irradiation embrittlement in nuclear reactor materials by magnetic first-order reversal curves

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02640
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 31010:Nuclear engineering-related
• Research Institution: Iwate University
• Principal Investigator: Kobayashi Satoru 岩手大学, 理工学部, 教授 (30396410)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 照射硬化 / 圧力容器鋼 / 磁気特性

Outline of Final Research Achievements

In this study, the possibility of evaluating irradiation hardening for reactor pressure vessel steels was examined using first-order reversal curve (FORC) method, which can simultaneously evaluate coercivity and interaction field distribution. Using FORC measurement equipment which employs induced voltage method, approximately 150 samples, with variable alloy-irradiation condition, were measured. For almost samples, a pronounced single FORC peak was observed in the two-dimensional FORC diagram and its position and width are found to depend on neutron fluence. By using the FORC method, a morphology of irradiation-induced nanoscale defects may be inspected in addition to an increase of their density.

Free Research Field

磁気工学

Academic Significance and Societal Importance of the Research Achievements

照射脆化の非破壊評価技術の開発は緊急課題であり、その中で磁気的手法は有用な手法の一つとして長年研究されてきている。1条件あたり１つの磁気パラメータを得る従来法に対して、1条件あたり２次元のFORC図情報を得る本手法により、照射誘起ナノスケール欠陥の形成過程に関する情報を、磁気的不均一性や磁気相互作用の観点から付加的に取得可能であることが分かった。照射硬化などの材料劣化の非破壊評価法として、磁気的手法の有用性の高さを示した本成果は、学術的及び社会的意義がある。