Correlation and flux tilt measurements of coupled-core reactor assemblies

Abstract

The systematics of coupling reactivity and time delay between cores have been investigated with a series of coupled-core assemblies on the AAEC Split-table Critical Facility. The assemblies were similar to the Universities' Training Reactor (UTR), but had graphite coupling region thickness of 450 mm, 600 mm and 800 mm. The coupling reactivity measured by both the cross-correlation of reactor noise and the flux tilt methods was stronger than for the UTRs, but showed a similar trend with core spacing. The cross-correlograms were analysed using the two-node model to derive the time delays between the cores. The time delays were compared with thermal neutron wave propagation, and found to be consistent when the time delays were added to the individual node response-function delays.