Japanese efforts in relation to BWR pipe cracking

The stress corrosion cracking was found in a Japanese Commercial BWR power plant first in 1974, then also in the others. To overcome this problem, much effort has been made to improve the stress condition, material and environment which are known to be the three causative factors of IGSCC. Also several studies have been carried out from the fracture mechanics point of view on the stress corrosion cracking behaviors in the BWR primary piping. Our experiences of pipe cracking, development of remedies and/or countermeasures examples of their application to our units and the fracture mechanistic research on piping LBB are shown in the following.