Evaluation of nanofluid coolant effects on VVER-1000/V-446 reactor using 3-D full core coupled neutronic and thermohydraulics analysis

A 3-D full reactor core simulation of VVER-1000/V-446 during full power normal operation is developed to investigate reactivity control and heat transfer improvements when using silver nanoparticles as the base coolant. Coupled neutronic/thermohydraulics analysis is performed using efficient coupling method in which the detailed neutronic model has been created in MCNP, and porous medium method has been used for the thermohydraulics simulation. Consistent with the porous medium approach, complexity of the thermohydraulics full core simulation fades away and reasonable radial and axial distributions of coolant temperature are obtained applying the distributions of power, which are related to the core neutronics. According to safety margins, the reactor operates safer with nanofluid in comparison with the traditional coolant owing to the higher negative temperature coefficient of reactivity. The outcomes indicate that minimum departure from nucleate boiling ratio using nanofluid is almost 9.5% higher, and nanofluid improves the reactor safety margins. (C) 2020 Elsevier Ltd. All rights reserved.