Hydrodynamics of the pressure and upper mixing chambers of the BN-600 reactor of the beloyarsk nuclear power station

Abstract

When the rated power of the BN-600 reacotr was first attained, coolant flow in the first circuit was investigated by a thermocouple method. It was observed that the temperature in the upper mixin~ chamber is nonuniform due to nonuniform heating in the core and blanket fuel assemblies and to the hydrodynamics of the chamber. According to the readings of thermocouples, temperature stratification was observed at the outlets of fuel assemblies (FA), in the reactor tank, and at the inlets of intermediate heat exchangers (IHE). It was found that there was no complete mixing of the coolant in the pressure chamber. Parallel flows moving along pressure conduits of different loops from the three main circulators of the first circuit MC-I mix only slightly in the pressure chamber; at the FA inlets they preserve the different temperatures they had at the outlets of the IHE of different loops. At the FA outlets the coolant flow preserves the different temperatures of the first circuit loops.