343 照射の複合作用を考慮した新しい材料損傷評価法の開発(OS10-3 照射劣化,溶接部評価,OS10 エネルギー機器の経年変化に関する健全性評価手法の開発とその適用(2))

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In core structural materials of next generation reactors such as a liquid-metal cooled fast breeding reactor and a supercritical-water cooled thermal or first reactor, materials' degradation behavior by neutron irradiation damage and thermal (cyclic) stress should be considered with fair accuracy in design process (including maintenance and repair plans), because the materials are used under higher temperature gradients and higher neutron flux fields than those in the present light water reactors. In the current experiential design rules, service lives of core structural components were determined by the materials degradation such as the increase of ductile-to-brittle transition temperature after post irradiation examination data. However, other materials degradations such as irradiation-assisted stress corrosion cracking (IASCC), which occurs by the degradation synergistically interacting with radiation hardening, local chemical composition change, swelling and radiation creep, should be considered reasonably in the design process of the next generation reactors, because of the anticipation of the beneficial effects by synergy of radiation damage. The radiation hardening and local chemical composition change at grain boundaries due to radiation-induced segregation increased with increasing dose. Above some threshold dose, swelling increased rapidly with increasing dose. Residual stress due to thermal stress and welding procedure decreased with increasing dose. To predict material failure by IASCC with reasonable accuracy, in this study, each material degradation phenomenon with different dose dependence was modeled with consideration of radiation induced stress relaxation. And then the models were integrated to simulate the failure behavior for the duration of reactor operation period. In this paper, the models obtained by ion-irradiation experiments and compared by data from neutron irradiation experiments were presented, and the concept of our new evaluation method and the programming code for the failure simulation were outlined.
一般社団法人日本機械学会の論文
2007-10-24

343 照射の複合作用を考慮した新しい材料損傷評価法の開発(OS10-3 照射劣化,溶接部評価,OS10 エネルギー機器の経年変化に関する健全性評価手法の開発とその適用(2))

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