Upgrading of highly elapsed degradation damage evaluation of structural materials for the light water reactors

Here were attempted not only to elucidate interaction between material degradation features and degradation properties at high temperature water environment, but also to conduct expansion protection and recovery evaluation of damage at welding portion remarkable in material degradation by using laser processing method and so on, on degradation of structural materials through with long elapsing term of nuclear power plants. And, figures on damaged area was prepared on a base of the obtained data. As a result, on effect of MnS, temperature and dissolved oxygen on high temperature water corrosion of low alloy steel A533B, it was found that degree of corrosion reduction were in an order of no-degas + MnS > no-degas > degas + MnS > degas. And, on evaluation of local corrosion after melt and solidification due to laser, it was found that when conducting TIG welding only, a large potential slope was observed at HAZ portion in response to shared area, and a fact exposed by serious corrosion potential could be confirmed. (G.K.)