A design approach for establishing creep strength reduction factor for repaired welds for fast reactor fuel pin end plugs

In the design and manufacturing of the nuclear components, there are no general guidelines and standards for accepting the number of repaired welds. In certain cases such as fuel pin end plug welding, the rejection of repaired welds has to be seen critically in order to avoid multiple handling of fuel pins filled with depleted Uranium pellets. In this context, detailed analysis has been carried out to see the possibility of accepting the end plug welds with one or two repairs based on test and evaluation. It is attempted to bring to a standard on methodology adopted for specifying number of welds for 500 MW FBR for the benefit of developers of FBR. In order to recommend the robust design rules for repaired welds for the consideration of inclusion in the future design codes, extensive test data on fuel pin end plug welds with variable number of welds have been generated and evaluated. In this paper, a design approach for obtaining creep strength reduction factor has been established based on a limited test data.

► Conducted experiment at high temperature and high pressure.
► Obtained experimental time to rupture for fuel pins with variable weld repairs.
► Given design approach to obtain the creep strength reduction factors.
► Recommendation to accept up to 2 weld repairs for PFBR fuel pin end plugs.