Phenomena Identification Ranking Exercise And Numerical Analysis For Advanced Small Module Molten Salt Reactor

There is a growing interest worldwide in advanced small module reactor due to it's outstanding safety and versatility.As an important feild of small module molten salt reactor research,safety analysis has received increasing attention.Phenomena identification and ranking proccess and program development can provide early stage technical support for safety analysis.Analytical tools have also been widely used by the international nuclear industry.In this article,phenomena identification and safety analysis has been carried out for primary loop and secondary loop of molten salt reactor-solid fuel.Firstly,according to the classification of boundary event in molten salt reactors,phenomena identification and ranking process has been carried out,and the safety-related phenomena are identified and ranked.Secondly,a TMSR-SF1 model based on RELAP/SCDAPSIM MOD 4.0 software was established to further quantify the identified key phenomena.Finally,for the lack of research data on secondary loop of molten salt reactor,the main components of the secondary loop have been modeled including the main steam turbine,power turbine,main condenser based on RELAP/SCDAPSIM MOD 4.0 software and safety analysis was carried out for the steam generator tube rupture accident,load shedding conditions.The result shows that the phenomena having significant impact but with limited knowledge are core coolant bypass flows,outlet plenum flow distribution,intermediate heat exchanger over/under cooling transients.The fluid mixing phenomena in the upper plenum identified in station blackout scenario is safe under priliminary design.The calculation results for secondary loop show that during the accident of the steam generator tube rupture,the fluctuation of the core parameters mainly occurs in the condenser and the temperature of the main condenser changes by about 5%.Under the load shedding conditions,the balance pressure of main condenser shifts by about 13% and maintains stability.The main equipment of the second loop thermal system can meet the design requirements when transients occur.The results of this paper can provide support for the research and development of advanced small nuclear reactors.