Heat transfer in a simulated spent fuel pool for different types of spent fuels

FERNANDO P. FARIA; RAONI A. S. JONUSAN; GODINO M. DARIO; SANTIAGO F. CORZO; DAMIAN E. RAMAJO; ANTONELLA L. COSTA; CLAUBIA PEREIRA

Congreso Virtual

Congreso; 15th INTERNATIONAL CONFERENCE ON HEAT TRANSFER, FLUID MECHANICS AND THERMODYNAMICS; 2021

University of Pretoria

Historically, the Spent Fuel Pool (SFP) of Angra II, from Brazil, has received standard spent fuel (SF) assemblies of uranium dioxide (UO2) discharged from Pressurized Water Reactors (PWR) of the Nuclear Power Plants (NPP) of Angra. However, in case of using Mixed Oxide (MOX) or thoriumbased fuels at a proportion of 1/3 or 1/4 of the total of fuel assemblies in their PWRs as it has been occurring worldwide, it would require further thermal studies of wet storage of the new mixed SF generated. It includes the determination of the water boiling time (Tb) of the SFP in case of breakdown of its external cooling system (ECS).This work presents studies of Tb of a simulated SFP storing mixed SF discharged from PWRs. The types of mixed SF studied include MOX plus UO2, oxide of thorium/uranium (UTh)O2 plus UO2, and oxide of thorium/transuranic (TRU-Th)O2 plus UO2. All the mixed SF was considered to contain 1/3 or 1/4 of either thorium-based fuels or reprocessed fuel. The simulations were implemented in CFX Ansys and OpenFOAM© codes. Tb from simulations with Ansys ranged from 4.05 h to 5.97 h, and from 3.45 h to 5.77 h from simulations with OpenFOAM©. Results show that, independent of the mixed loading pattern of the SFP, the water would reach the saturation temperature more rapidly when (TRU-Th)O2 was present. By contrast, when MOX was present, Tb was greater.