Worth of boron rod in the reactor MOATA

Abstract

The U235 fuel increase required to compensate for the insertion in MOATA of an enriched boron rod is measured. The DIFF code is used to calculate the mass increase and comparison with the experimental result provides a check on the theory incorporated in the code. In addition to the experimental check, a simplified calculational mock-up of the experiment is used as the basis of a more detailed comparison between the diffusion theory and transport theory. The worth of the rod as calculated by the diffusion theory is high by 10 per cent when compared to experiment and low by about 3 per cent when compared to transport theory. In general, the neutron fluxes calculated by the diffusion theory agree to within 2 per cent with those from transport theory.