A coupled thermohydraulic/neutronic investigation of noise propagation in VVER-1000 reactor usingAl2O3 nanofluid coolant

Thermohydraulic and neutmnic coupling for the VVER-1000 reactor carried out by applying Al2O3 nanofluid as coolant in this paper. The simulation took place in two sections; with the neutronic section, the discretization of the nodal (average current) method for dissociation of two-group diffusion equations accomplished and with the thermohydraulic section, the finite volume method for decomposition of conservation equations (mass, momentum and energy) in static and transient states was used. In this study, neutronic and thermohydraulic noises (Fourier transform) in the frequency domain were analyzed by applying propagation noise sources in the VVER-1000 reactor core. With the neutronic section, macroscopic cross sections were generated making use of Al2O3 nanofluid as coolant with different volume fractions by means of WIMS-D5 computation code. The ultimate goal of the paper is to perform neutronic and thermohydraulic simulations of VVER-1000 reactor using Al2O3 nanofluid as coolant in the frequency domain. Two separate noise scenarios for the inlet nanofluid coolant (coolant temperature and velocity) with different volume fractions of Al2O3 nanoparticles (0.001%, 0.1% and 1.0%) were considered in the analysis. Final results showed that the core power peaking factors will be less influenced by inlet fluctuations when applying more nanoparticles in the reactor coolant.