BWR power transient optimization with PRESTO-POWERMAX

POWERMAX is an ABB-Atom power optimization algorithm developed for use as a boiling water reactor (BWR) operational support tool for prediction of optimal return strategies following power transients. Using input target power versus time data together with relevant data describing the initial core state, including distributions of burnup, void, void history, control rods, and poison, it basically searches for the maximum power path, with nonnegative thermal and pellet/cladding interaction margins as constraints. The model uses a combination of a three-dimensional (3-D) simulator and a closely coupled, one-dimensional (1-D) axial model, which is used as an alternative quick tool in the optimization search, provided the radial power distribution is relatively unchanged. This assumption is considered reasonable in normal control-line operation with unchanged control rod positions. The algorithm, originally built around the POLCA method, has now been also adapted to the PRESTO simulator.