In-Pile Performance of TRISO Particle Used Stainless Steel Foams as Buffer Layer

Abstract

Thermal conductivity of TRISO particle deteriorated during in-pile operation due to the shrinkage of the low density carbon buffer layer and the gap appeared. In order to solve this problem, stainless steel foam was used to replace the low density carbon buffer layer as buffer layer in TRISO particle. The in-pile performance of the new type TRISO particle was simulated, and the result indicated that the stainless steel foam can avoid the gap between the buffer and the IPyC layer which can increase the thermal conductivity and decrease the kernel temperature during operation process; at the same time, regardless of stainless steel foam or low density carbon buffer layer used as buffer layer, the stress on IPyC and OPyC layers all exceeded the strength of the two layers. Hoop stress on SiC layer decreased with the elasticity modulus of metal foam, and the stress can be controlled by decreasing the elasticity modulus. To sum up, metal foam with high porosity and low elasticity modulus can be selected as the buffer layer to improve the thermal conductivity and assure the integrity of the coated layer and increase the life time. This study offered the optimization direction of TRISO particle for engineering application.