Monte Carlo applications to core-following of the National Research Universal reactor (NRU)

Reactor code TRIAD, relying on a two-group neutron diffusion model, is currently used for core-following of NRU - to track reactor assembly locations and burnups. The Monte Carlo (MCNP or SERPENT) full-reactor models of NRU can be used to provide the core power distribution for calculating fuel burnups, with WIMS-AECL providing fuel depletion calculations. The MCNP/WIMS core-following results were in good agreement with the measured data, within the expected biases. The Monte Carlo methods, still very time-consuming, need to be able to run faster before they can replace TRIAD for timely support of NRU operations. (author)