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Master logic diagram based internal initiating events identification for

core radioactive material release in molten salt cooled pebble bed reactor YANG Qun MEI Mudan SHAO Shiwei JIAO Xiaowei HE Zhaozhong CHEN Kun

Shanghai Institute of Applied PhysicsCASShanghai 201800 AbstractProbabilistic safety analysis of molten salt cooled pebble bed reactor contributes to analyze the safety and reliabilityto identify the weaknesses in design and reduce potential risks. Initiating eventsIEsidentification is the foundation. For molten salt cooled pebble bed reactor current international design stage and typical designthis paper identifies the internal IEs for core radioactive material release under full power condition. For the lacks of engineering evaluationoperational experience and similar reactors that can be referencedIEs identification is completed by the combination of functional analysis and master logic diagram analysis. Through the implementation of this methodthis paper determined six initiating event groups including specified transientsloss of flowloss of coolantloss of heat sink and special common cause failure. This initiating event groups all could lead to the radioactive material release from core by affecting the nuclear heat generationheat transport and structural integrity of the shield. The results also imply that the combination of functional analysis and master logic diagram analysis is an effective method for the IEs identification in molten salt cooled pebble bed reactor. Key words probabilistic safety analysis molten salt cooled pebble bed reactor internal initiating eventsmaster logic diagram

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