Local In-Core Power Measurements with Out-of-Core Gamma Detectors

Preliminary measurements have been made of local power level inside a reactor core using two collimated gamma-ray beams containing reactivity induced noise information. A conventional two-input correlator was used for the electronics. The results indicate that power distribution in a reactor probably could be obtained to a core depth of ∼10 cm with simple detecting apparatus mounted external to the core. A plot obtained with correlated gamma rays closely resembled one obtained by conventional cobalt wire neutron activation.