Derivation of a Correlation Between Fuel Temperature and Power for CANFLEX Fuel Bundles

Abstract

Using the ELESTRES fuel-modelling code and the WIMS-AECL lattice-physics code, a correlation between bundle-average fuel temperature and bundle power has been derived for CANFLEX natural-uranium fuel. WMS-AECL calculations provided the relationship between bundle power and the power of the various pins in the bundle, and the ELESTRES code provided the pin volume-average fuel temperature versus pin linear power at various values of burnup. A uniform bundle-average temperature, which reproduced the lattice-cell reactivity for the CANFLEX bundle, was then determined at various values of bundle power and fuel burnup. This bundle-average fuel temperature was then correlated to bundle power. and the correlation was programmed into RFSP (Reactor Fuelling Simulation Program) for use in full-core, local-parameter calculations. Some comparisons were made of the core power distribution obtained with CANFLEX fuel with that obtained with 37-element fuel. In the time-average model, the maximum channel and bundle powers were very close (difference about 0.1%) to those calculated with 37-element fuel in core, and the maximum difference in any bundle and channel power was less than 0.2%. An 8-bundle-shift refuelling of channel N14 in a 37-element-fuel time-average core was simulated; the maximum bundle power was found to be only very slightly (about 0.1 %) higher for the refuelling with CANFLEX fuel than when 37-element fuel was used.