Core defueling strategies and monitoring

A number of CANDU reactors went through refurbishment during which some major components were replaced, and there are some more reactors that will be refurbished in the near future. Core defueling is an important step in this process. Effective, continuous monitoring of the neutron flux is always required during core defueling, even when the reactor is deeply sub-critical is still a requirement as per stations Operating Policies and Principles. Different core defueling and neutron flux monitoring strategies exist based on Operating Experience (OPEX) and are briefly discussed. Bruce B core defueling was simulated using MCNP [1] and the RFSP [2] 2-group neutron diffusion code and their predictions were compared. (author)