Analysis of lead-bismuth eutectic-cooled solid reactor under flow blockage accident by 3D neutronics thermal-hydraulics coupling method

As the most common and serious accident in liquid metal-cooled reactors, the occurrence of a flow blockage accident may threaten the integrity of the cladding and the safety of the core. Therefore, the accurate prediction of fuel and cladding under blockage accidents is particularly important in reactor design and thermal --hydraulic analysis. This paper uses a three-dimensional neutronics thermal-hydraulics coupling method to analyze the blockage accident of a lead-bismuth-cooled solid reactor proposed by the Innovative Nuclear System Laboratory (INSL) of Shanghai Jiao Tong University. Based on the accurate and material models, the solid reactor was modeled, and 15 blockage accidents were carried out. The effects of the blockage's radial position, thickness and axial position on the fuel and cladding temperature were compared. Unlike the conventional open-channel blockage, the results of the closed-channel blockage accident analysis show that the thickness and axial position of the blockage has less influence on the maximum fuel and cladding temperatures but slightly affect the fuel and cladding axial temperature dis-tribution. Meanwhile, the blockage accident in the closed channel is more serious, and the maximum temperature rise of fuel and cladding is higher, but both are lower than the limit value required by the design criteria.