Experience In Operating Gas-Cooled Reactor Steam Generators of U.K. Design

The oxidation of mild steel components in reactors and steam generators is a widely reported problem associated with Magnox-type reactors. The advance gas-cooled reactor is a direct development of the Magnox-type reactor. Experience with the steam generator has been good; problems have been detected and solved. The problems were

1. gas side corrosion of the 9 Cr—1 Mo superheater section
2. stress corrosion of the austenitic superheater section
3. creep of the transition joint between the 9 Cr—1 Mo and austenitic sections
4. erosion-corrosion in the economizer inlet orifice carriers.

Although the metallurgical phenomena associated with each problem are different, the first three lead to temperature constraints (high and low) that necessitate development of a common operational procedure to accommodate each constraint.