Gamma Heating Estimate at the McMaster Nuclear Reactor

Abstract

Gamma heating is an important issue that can contribute significantly to the heat generation in the reactor core, either by prompt- or delayed decay processes. While photons account for around 7% of the total energy produced in fission along with the additional component of capture gamma production, this is still a considerable amount of energy created. In this paper, a measurement has been carried out to estimate the nuclear heating using a Halden-type Gamma Thermometer (GT) at the McMaster Nuclear Reactor (MNR). It was found that around 84 ± 8.4 % of the measured nuclear heating in non-fuel regions is due to the prompt gamma, including radioactive captures, and a maximum of around 14 ± 1.4 % is due to the decay gamma heat. The latter usually occurs immediately after the reactor shuts down and then it decreases exponentially.