SFR safety design concept and related safety R&D in China

Defense in depth safety design in CEFR: CEFR functions are designed according to the defense in depth principle, which provide a series of multiple layers of defenses. Level 1 defense, is to protect from deviating from normal operation and system failure, by providing a correct and conservative design, construction, maintenance and operation of the nuclear power plant. • Level 2 defense, is to detect and correct deviation from normal operation, to protect anticipation operational events from escalating to accident conditions, by designing certain special systems, i.e. reliable shutdown system, reactivity control system, various protection system and monitoring and detecting system, and developing operating procedures. Level 3 defense, is to ensure reactor shutdown safely, maintain a safe and steady shutdown state and maintain at least one radioactivity barrier intact provided that design basis accidents occur, by designing and equipping engineered safety systems and inherent safety design. • Level 4 defense, is to ensure radioactivity release are remained as possible as practically low for severe accidents which already likely are beyond design basis, by developing accident management procedures. The most important goal is to protect confinement function. • Level 5 defense, is to mitigate radioactivity consequences caused by potential radioactive materials from accident conditions, by equipping appropriate equipments in the emergency control centre and developing in site/off site emergency response plan.