Axial offset anomaly: coupling PWR primary chemistry with core design

摘要

Axial offset anomaly (AOA) in pressurised water reactors (PWRs) is a larger than expected negative flux depression beginning approximately at 5000 MWd/MtU feed fuel burnup. AOA can threaten the full power shutdown margin and thereby force a costly derate. More than 20 US cores have exhibited AOA, one seriously enough to have derated to 70/100 Power for several months of the cycle. Deregulation of The US power market demands improvements in fuel Economics; this means extended cycles with high boron At the beginning of core life, core design with Increased sub-cooled steaming, and shortened outages With less effective corrosion product clean-up.