Coupled Neutronic And Thermal-hydraulic Analysis Of TMSR-SF1 At Steady State

Reactor systems are huge and complex,and their components are designed and constructed according to the theoretical basis of many disciplines.The design and research of the reactor core are the most important,and the two main aspects of the reactor core design are neutronics and thermal hydraulics.In exploring the complex interaction mechanism between neutronics and thermal hydraulics,researchers have developed a variety of coupling methods and mechanisms.These coupling methods have been further improved thanks to evolving computing power and continuous expansion of computing resources.10MW solid-fuel thorium molten salt reactor is a new type of molten salt reactor proposed by researchers at Shanghai Institute of Applied Physics,and the research on its key technology is fundamental to independently develop the molten salt reactor.In this paper,based on the neutron transport calculation software MCNP5 and the computational fluid dynamics software ANSYS Fluent14.0,a coupled analysis is conducted to investigate TMSR-SF1's core design concept,technical characteristics and operating conditions.The three-dimensional steady-state neutronics/thermal-hydraulic coupling study is carried out by using C ++ programming language to write the coupling feedback data.The temperature distributions of solid fuel pebbles and TRISO particles are calculated by Fluent using finite volume method,with the calculating parameters generated from the coupling calculation results in order to provide guidance and data support for the subsequent design optimization of the reactor.Based on the main design parameters and operating conditions of the solid-fuel thorium molten salt reactor core,the corresponding neutron physical model and thermal model are constructed,and simplified by using the simplified TRISO particle structure and the porous media model.The power density distribution,the coolant temperature and the density are regarded as the coupling feedback data,and the effective multiplication factor as the coupling calculation convergence criterion.The program for transmitting the coupling feedback data is developed by using the C ++ programming language.The neutronics and thermal-hydraulic coupling calculations were carried out for TMSR-SF1 design.The differences between the neutron physical parameters and the thermal hydraulic parameters before and after the coupling were discussed.Finally,the solid fuel ball and the TRISO particle temperature were calculated by the coupling calculation distributed.It is found that the introduction of the coupling calculation has a significant effect on the thermal-hydraulic calculation of the TMSR-SF1: the maximum temperature of the core increases from 638.948 ? to 640.643 ?,and the increase is 1.695 ?,the core coolant temperature discrepancy is obvious,and the maximum temperature difference before and after coupling is 7.584 ?,the position of which is the axial height of the core is 1.5m.Due to the difference of the temperature before and after the coupling,the neutron physical parameters such as the neutron flux density and the power density distribution are changed in different degrees.The calculation of the temperature distribution of the fuel pebbles and TRISO particles shows that the operating temperature of the 6cm fuel ball and the 3cm fuel pebbles and the TRISO particles are within the permissible range and the difference between the center and the surface temperature is small at the initial loading operation condition.thus ensuring the safe operation of the fuel pebbles.