Material issues relating to high power spallation neutron sources

高出力中性子源の材料問題

二川 正敏  

Futakawa, Masatoshi

高出力水銀ターゲットにおける材料問題に関する研究成果、すなわち、液体金属脆化による疲労き裂伝播速度の上昇や破壊脆性値の増加に関する研究成果、イオンビーム照射による照射脆化評価及びナノインデンテーションによる極微小領域の力学特性評価法に関する研究成果、陽子線入射励起衝波による生じるマイクロピット群損傷機構に関する研究成果について総括的にまとめると共に、さらにその抑制技術に関する技術開発について報告する。

Innovative researches using neutrons are being performed at the Materials and Life Science Experimental Facility, MLF, at the Japan Proton Accelerator Research Complex, J-PARC, in which a mercury target system is installed for MW-class pulse spallation neutron sources. The structural materials of the mercury target are subjected to irradiation damage due to protons and neutrons, very high cycle fatigue damages due to repeated pressure waves caused by the proton beam bombardment in mercury and so-called liquid metal embrittlement. That is, the structural materials must be said to be exposed to the extremely severe environments. In the paper, research and development relating to the material issues in the high power spallation neutron sources that has been performed so far at J-PARC is summarized.