Subchannel analysis of TiO2 nanofluid as the coolant in VVER-1000 reactor

•The present article is a thermal-hydraulic analysis of TiO2 nanofluids as a coolant in VVER-1000 reactor by subchannel method.•The coolant temperature increases with increasing concentration of nanoparticles.•For 10% volume of nanoparticles, the coolant temperature difference with pure water is about 20 °C.•By using TiO2 nanofluids as a coolant, the plant efficiency will be increased.

The main objective of this study is to predict the thermal-hydraulic behavior of TiO2 nanofluid as the coolant in the hot fuel assembly of VVER-1000 reactor core. The subchannel's continuity conservation, momentum conservation and energy conservation were established. The conservation equations and conduction heat transfer equation for fuel and clad have been derived and discretized by Finite volume method. The turbulent and diversion cross flow were considered between adjacent subchannels. All subchannels were correlated and numerical analysis was made from the inlet of the core to the outlet. The velocity and enthalpy of the coolant was obtained in each subchannel along core's axial direction, therefore the surface temperature of the fuel rods were obtained as well. Finally the analysis results for TiO2 are compared with the pure water results. The achieved results show that as the concentration of TiO2 nanoparticles increases, the temperature of the coolants grows up and the central fuel temperature can be reduced.