Natural Circulation Studies On The Integral Small Modular Fluoride Molten Salt Cooled High Temperature Reactor

Nuclear energy has become one of the most important energy for human social development.To pursue higher safety and economy,six candidate reactors has been put forward,including the molten salt reactor(MSR),as one of the generation IV nuclear reactor.Simultaneously,small modular reactor with multi-purpose,low cost,strong adaptability and other characteristics,has become the focus of international nuclear energy research today,and a variety of types of design has been proposed.Based on these,the concept of integral small modular fluoride molten salt cooled high temperature reactor is being proposed,which uses FLiBe salt as the coolant,integrates the heat exchanger in the reactor vessel,adopts the natural circulation cooling method in the primary circuit.The reactor has characteristics of the molten salt reactor,small modular reactor and natural circulation reactor,which leads to a good inherent reliability.In this dissertation,several key issues related to the natural circulation are studied,including thermal hydraulic design,transient safety analysis and uncertainty and sensibility analysis.Firstly,the single channel model,pressure drop model and heat exchanger model are used to complete the program design.Then,four typical accidents are performed with RELAP5-MS system analysis program and the inherent safety features of the reactor are evaluated.Finally,the uncertainty and sensitivity analysis of the relevant input parameters is performed,and the parameters which have important influence on the development of the accident are obtained.It further verified that the reactor has inherent safety features.In this study,the base of the thermal hydraulics and safety analysis of the reactor is established,and the parameters with great influence on the transient features are obtained.The results show that the reactor is feasible and have certain value and significance for the study of the advanced nuclear energy system which is coordinated with the development of economy and safety.It provides some basic support for the design of the integral small modular fluoride molten salt cooled high temperature reactor.Some experience for the safety analysis of this type of reactor is accumulated.