Investigating the possible advantage of using LM bonded gap instead of helium in Ap-1000 nuclear power reactor

Abstract

This work focuses on the viability of using liquid metal bonded gap instead of the traditional helium (He)-gap through investigating its effects on the neutronic, thermal–hydraulic, and solid mechanics analyses. The shortcoming of using a He-gap is the high thermal resistance of helium, which causes overheating and much heat accumulation inside the fuel, and hence causes many problems with the fuel‘s solid mechanics behavior. To reduce both the heat accumulation and overheating inside the fuel material, LM boned gap was applied. The obtained results showed a slight difference in the various neutronic parameters, while in the thermal–hydraulic analysis, an excellent enhancement in the maximum fuel temperature happened, which reduced the heat accumulation in the fuel material. Also, in solid mechanics analysis, the enhancement that came from decreasing the fuel temperature decreased both the thermal expansion of the fuel and the von-Mises stress that acts on it.