Abstract: On the basis of core damage assessment method for PWR and combined with the characteristics of 600 MW demonstration sodium cooled fast reactor, this paper proposes an assessment model for core damage of sodium cooled fast reactor based on the comprehensive assessment of on-line monitoring instrument readings as the main model while the radionuclides sampling assessment as the auxiliary model. The developed software of core damage assessment for sodium cooled fast reactor has been applied to the 600 MW demonstration sodium cooled fast reactor project.

Key words: sodium cooled fast reactor, core damage assessment