Actinide-only burnup credit for pressurized water reactor spent nuclear fuel - III: Bounding treatment of spatial burnup distributions

摘要

A flat uniform axial burnup assumption does not always conservatively estimate the pressurized water reactor spent-fuel cask multiplication factor. An alternative approach is to augment the multiplication factor from the axially uniform calculation by an appropriate k_(eff) bias determined by applying the limiting axial burnup profiles and assuming a single-assembly cask configuration. However, because of their conservative nature, k_(eff) bias curves are recommended only for a large reactivity in the particular cask of interest. The horizontal burnup distribution poses less reactivity concern because it is bounded by assuming a conservative horizontal burnup gradient within individual assemblies and the most reactive arrangement of multiple assemblies.