Preliminary Study on the Identification of DECs Without Significant Fuel Degradation in New NPP Designs

New nuclear safety objectives and principles are being studied in main nuclear power countries and organizations after Fukushima Dai-ichi nuclear accident, to further improve the safety level of nuclear power plants (NPPs). Based on International Atomic Energy Agency (IAEA) Specific Safety Requirements (No.SSR-2/1), “Safety of Nuclear Power Plants: Design” (HAF102-2016) is issued in China. The concept “design extension condition (DEC)” is put forward, which is intend to enhance the plant’s capability to withstand accidents that are more severe than Design Basis Accidents (DBA). DEC could include conditions without significant fuel degradation (DEC-A in this paper) and conditions with core melting (DEC-B in this paper), e.g. severe accident. In this paper, the DEC-A and its application was discussed preliminarily, firstly, the development and connotation was introduced, then the identification of DEC-A, and the safety analysis principles of DEC-A were mainly described. This study may play a valuable role for implementation of new nuclear safety requirements in China.