Structural materials used in sodium cooled fast reactors (SFRs) shall have good high temperature low cycle fatigue and creep properties, adequate weldability to fabricate large size components and shall be compatable with the liquid sodium environment in service. Austenitic stainless steels have been the natural choice for structural components of SFRs worldwide. The creep design life of SFR component is very long and is of the order of 40 years. This calls for robust creep life rediction models to convert short and medium term laboratory rupture data to design life. This paper discusses the application of creep dissipation energy concepts to predict creep rupture life of four nitrogen alloyed grades of 316 LN SS.