Influence of some parameters on the void reactivity and pin power calculation for typical CANDU cells

The void coefficient of the reactivity in a typical CANDU cell is positive and it represents a sensitive issue for the regulatory discussions. The paper investigates the influence of some parameters (as geometry, composition, temperatures) on the void reactivity and power distributions. The methodology is based on integral transport calculation by the first flight collision probability approach (WIMS and CP₂D codes). The results offer a general view regarding the importance of different parameters and physical phenomena on the magnitude of the void reactivity, useful for educational & training purpose, and for the future development of new fuel bundles. The influence of each parameter is separately treated in order to understand the individual importance in the global effects. (authors)