Storage of Natural-Uranium Fuel Bundles in Light Water: Reactivity Estimates

Abstract

This paper reports a study of the system reactivity of the storage of 37-element CANDU natural-uranium fuel bundles in different configurations in light water. The study used the Monte Carlo method to calculate the reactivity worth of CANDU fuel bundles immersed in light water. All the configurations that were studied of 37-element CANDU natural-uranium fuel bundles in a light-water environment, whether fresh fuel or plutonium-peak fuel, satisfied the criticality-safe criterion with a reactivity at least 50 mk subcritical. The largest value of bff calculated was 0.928 for an infinite hexagonal lattice of plutonium-peak fuel. This paper demonstrates that the possibility of having a nuclear criticality excursion with 37-element CANDU natural-uranium fuel bundles in light water is remote.