Study on hydrogen-defect interaction in nuclear materials by using PAS and TDS

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H03517
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Nuclear engineering
• 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): 大澤 一人 九州大学, 応用力学研究所, 助教 (90253541)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 陽電子消滅法 / 中性子照射 / 電子線照射 / 昇温脱離分析

Outline of Final Research Achievements

Deuterium trapping at irradiation-induced defects in tungsten, a candidate material for plasma facing components in fusion reactors, was revealed by positron annihilation spectroscopy. Pure tungsten was electron-irradiated (8.5 MeV at ~373 K and to a dose of ~1 mdpa) or neutron-irradiated (at 573 K to a dose of ~0.3 dpa), followed by post-irradiation annealing at 573 K for 100 h in deuterium gas of ~0.1 MPa. In both cases of electron- or neutron-irradiation, vacancy clusters were found by positron lifetime measurements. In addition, positron annihilation with deuterium electrons was demonstrated by coincidence Doppler broadening measurements, directly indicating deuterium trapping at vacancytype defects.
This is expected to cause significant increase in deuterium retention in irradiated-tungsten.

Free Research Field

原子力材料

Academic Significance and Societal Importance of the Research Achievements

水素脆化は広い学問分野にまたがる学際的な課題であり、これまでに多くの研究が行われてきた。本研究は、実験手法および理論計算の最近の進歩をもとに水素－空孔型欠陥の相互作用に焦点を当てるものであり、水素脆化研究において水素拡散・捕獲プロセスをより良く理解するための材料科学からの知見を与える。原子力材料の劣化機構解明につながるのみならず、材料科学的にも大きな意義がある研究である。