CASS(Cast Austenitic Stainless Steel) materials are used in pressure-boundary components, such as piping and pump casing in power plant. When CASS components are exposed to high temperature (i.e. over 280oC) for a long time, thermal embrittlement could occur. Thermal embrittlement susceptibility of pipings and pump casings are determined by calculate the ferrite contents and fracture toughness. For some piping components, ferrite contents exceed the criterion value, are potentially susceptible to thermal embrittlement. But fracture toughness value is high enough to satisfy susceptibility criterion for all CASS components. Also flaw tolerance evaluation is assessed to piping and pump casing. As a result, there were no significant thermal embrittlement risk on CASS components.

The purpose of this study is to evaluate the corrosion protection properties of Zn/Sn metal spray method according to the contents ratio of Zn and Sn by CASS test. Also, the corrosion protection life of Zn/Sn metal spray method is evaluated by the comparing between the corrosion properties of Zn metalizing method and Zn/Sn metal spray method using CASS test. As a result, it was confirmed that the optimum content ratio of Zn/Sn in metal spray method is 60:40(65:35) (Zn : Sn volume ratio) in aspect of corrosion protection properties and construction properties. Also, it was confirmed that the Zn/Sn metal spray method had more than 3 times of corrosion protection properties cmparing the Zn matalizing method.