General Electric nuclear reactor safe-end cracking

Used to illustrate that restraint converts distortion into residual stress. The GE safe-end welds carried tensile residual stresses on the inside surface (where borated quench water contacted them); the fix was developing procedures that produced compressive residual stresses on the inside.

Now if the whole thing is restrained you don't get distortion, you just get huge residual stresses — tensile residual stresses right there, compressive residual stresses on the bottom. That was what General Electric was finding with their stainless steel welds in the reactor safe ends. These are two or two and a half foot diameter pipes where you'd flood the reactor with borated water if you had a problem. You quench the reactor by flooding it with borated water. The problem is, those pipes were one and a half to two inches thick, and they had tremendous tensile residual stresses on the inside. One of the things they did is they developed welding procedures that created compressive residual stresses on the inside, where it was in contact with the water.