Loop Studies Addressing the Hydraulic Impact From the Presence of Part-Length Fuel Rods Within a BWR Fuel Element, Using Water and Air-Water Mixtures at Room Temperature and Low Pressure

There are a number of reactivity incidents which could possibly occur at low pressure in boiling water reactor (BWR) cores, and some of them may cause local boiling — entailing reactivity feed-back. Unfortunately, theoretical studies of events of this nature are somewhat hampered by the dearth of knowledge about the thermal-hydraulics involved. The research presented here addresses one particular aspect of this issue: how is BWR core thermal-hydraulics — at low pressure — affected in such fuel assemblies where some full-length rods have been replaced by part-length rods?