Advanced materials for structural components of Indian sodium-cooled fast reactors

摘要

The performance of fast reactor (FR) working under high temperature, moderate pressure and intense neutron irradiation depends on its structural materials. Type 316 LN austenitic stainless steel with 0.02-0.03 wt.% carbon and 0.06-0.08 wt.% nitrogen is generally used for structural components of FR along with modified 9Cr-1Mo ferritic steel for steam generator. With an aim of enhancing the life of FR, efforts towards the enhancement of strength of the materials are been described. Nitrogen content in the 316 LN steel has been increased for optimizing the tensile, creep, fatigue and creep fatigue interaction strengths. Both the tensile and creep strength were found to increase with nitrogen content; whereas the fatigue and creep fatigue interaction strength have optimum values at around 0.12 wt.% of nitrogen. Based on the study, nitrogen content in 316 LN steel has been optimized at 0.11-0.13 wt.% for optimum combination of strengths. Weldability study has been performed and matching welding consumable has been developed.