Welding of austenitic stainless steels for the fast reactor programme

Abstract

For the Prototype Fast Breeder Reactor (PFBR), a modified version of 3161 SS, designated as 316L(N) SS, has been chosen as the major structural material. In order to reduce the risk of sensitisation, the carbon content has been reduced to < 0.03 wt-%, and to compensate for the loss in strength due to the reduced carbon content the nitrogen content has been specified to be -0.08 wt-%. For fuel clad and wrapper applications, a radiation-resistant variation of 316 SS containing titanium (about 6 times the carbon content) named Alloy D9, has been chosen. This paper discusses the weldability problems associated with these austenitic stainless steels, including their dissimilar metal joints, chosen for use in the construction of PFBR. The importance of hot cracking evaluations in determining the fabrication weldability of these austenitic stainless steels is also discussed in detail.