Investigation of the Effects of Hydrogen on Neutron Irradiation Degradation of Ferritic Steel through the Development of High-Temperature Hydrogen Atmosphere Irradiation

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H02661
• 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: Tohoku University
• Principal Investigator: Toyama Takeshi 東北大学, 金属材料研究所, 准教授 (50510129)
• Co-Investigator(Kenkyū-buntansha): 秋山 英二 東北大学, 金属材料研究所, 教授 (70231834) ; 波多野 雄治 富山大学, 学術研究部理学系, 教授 (80218487)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 中性子照射 / 陽電子消滅 / 3次元アトムプローブ / 原子炉圧力容器鋼

Outline of Final Research Achievements

We investigated the effect of hydrogen on neutron irradiation effects in ferritic steel. After neutron irradiation of A533B steel (a representative material for reactor pressure vessels) in vacuum or hydrogen environments, we examined the effects of hydrogen on the formation and growth of irradiation defects (atomic vacancy clusters), the diffusion behavior of solute atoms, and the solubility limit concentration. Copper was chosen as the solute atom, which is important in reactor pressure vessel steel. In the formation and growth of irradiation defects, it was suggested that the growth of irradiation defects might be suppressed when neutron irradiation occurred in a hydrogen environment. On the other hand, in solute atom diffusion and solid solution, the effect of hydrogen was hardly observed. This is thought to be due to the bonding between vacancies and hydrogen.

Free Research Field

原子力材料

Academic Significance and Societal Importance of the Research Achievements

フェライト鋼は最重要の原子力材料の一つであり、中性子照射による材料特性劣化や水素脆化が盛んに研究されているが、照射と水素との重畳効果を調べた研究例は多くない。本研究では、同一試料を真空中または水素環境下で中性子照射し、照射欠陥や溶質原子の挙動に対する水素効果を調べた。また、水素環境下での中性子照射を行うための照射装置を開発した。以上により、照射・水素の重畳効果研究の端緒となる結果を報告したとともに、今後さらなる照射・水素研究を進展させる素地を整えることができた。今後、金研大洗センターの共同利用照射を通して幅広い原子力材料研究に利用されることが見込まれる。