Corrosion resistant cladding as an intergranular stress corrosion cracking countermeasure

For several years now, most boiling water reactors have been forced to run at a low availability as the intergranular stress corrosion cracking (IGSCC) at the weld heat-affected zones of type 304 austenitic stainless steel pipings was found. IGSCC occurs if stress (residual stress due to welding, operating stress etc.), material condition (sensitization due to welding, content of alloying elements etc.) and environmental factor (dissolved oxygen in reactor coolant, corrosion products etc.) exceed the threshold simulataneously. Many researchers and engineers have so far tried various measures to solve these problems. The corrosion resistant cladding (CRC) process introduced here is a method of cladding with weld deposited metal (buttering material) the pipe inner walls which are sensitized owing to the welding of joints, and consequently improving the SCC-resistance. The results of buttering material screening tests and the demonstration tests on 4B and 8B pipes used in actual plants are also reported