Dynamic range and time response of a new hafnium neutron detector

A Babcock and Wilcox hafnium neutron detector was evaluated for use in measuring shut-down speed of a reactor during fast scram tests. The detector measured neutron flux over a dynamic range of eight decades and responded in a time that was short compared to 50 microseconds. Response was determined inside the cavity of a Godiva reactor operated in continuous and pulsed modes to generate power levels from 100 watts to 10/sup 10/ watts. The detector will provide neutron measurements previously unavailable for pulsed reactors and is already being used for the fast response part of an in-core reactor power monitor at Savannah River Plant in Aiken, South Carolina. 2 refs., 7 figs.