Experimental Measurement of Gamma Heat in the High Flux Isotope Reactor

The combined neutronic heating from gamma and neutron attenuation was measured in stainless steel and graphite samples irradiated in the High Flux Isotope Reactor (HFIR). Measurements were made at intervals during a reactor fuel cycle and at various elevations with respect to the reactor core. Peak energy depositions measured were 13.6 W/g in graphite and 16.6 W/g in stainless steel. The experiments illustrated the importance of considering local environment, especially near by radiation sources and sinks, as well as the geometry of the material, when estimating energy deposition rates.