Volume 3, Issue 8 (September 2006)
Characterizing the Time- and Energy-Dependent Reactor n/γ Environment
In a reactor pulse, the early radiation has a neutron/gamma component resulting from the prompt fission neutron and gamma radiation and from the neutron-induced secondary gammas. However, after the primary reactor pulse, the radiation environment also includes a time-dependent delayed neutron and gamma component. At even later times, the material activation dominates the source term. When active tests are conducted in the reactor, the radiation environment at a particular time may not be well characterized by the time-integrated spectrum provided by the typical radiation transport calculations. This paper defines the steps that are required to adequately model the time- and energy-dependent radiation environment in the reactor environment. This paper also compares the time-dependent response from a range of active dosimeters in a reactor pulsed environment and shows how the n/γ mixed-field response for the dosimeters and the changing radiation field can influence the interpretation of the dosimetry.