Research for the heat leakage caused by gaps on barrel insulation structure of reactor pressure vessel

Due to the function requirements of the Cavity Injection and Cooling System, the barrel insulation structure of HPR1000 reactor pressure vessel has been greatly improved compared with the previous projects. In the past, the empirical formula method was used to evaluate the thermal properties of the insulation, but the influences of the support structure and the excessive gap on insulation are difficult to evaluate. In this paper, the fitting formula of the equivalent thermal conductivity and the qualitative temperature of the insulation have been obtained firstly through the heat transfer test. Then, ANSYS Fluent was used to simulate the barrel insulation structure with gaps of HPR1000. A circumferential 15° model was established to obtain evaluation method for flow leakage with gaps in hot state, and then a whole model of the barrel insulation structure with gaps was established to obtain heat loss of insulation based on calculation of flow leakage. The sensitivity of gap size and ventilation parameters to heat leakage was further analyzed. Finally, it was indicated that, by minimizing joint gap length, setting of overlaps, controlling cold gap, optimizing structure of insulation support, the effect of heat leakage caused by gaps can be reduced. © 2019 Xi'an Jiaotong University