Reactivity Accountability Attributed to Reflector Poisons in the High Flux Isotope Reactor

Impact of HFIR LEU Conversion on Beryllium Reflector Degradation Factors

“…This means that the conditions for higher gas production are created in regions where the fastneutron flux is higher, such as in the removable reflector. Low-energy neutronic channels exist for gas production also, such as the 3 T/ 3 He production and the α production that originate from 6 Li. However, unless this 6 Li isotope already exists (such as an impurity), it must be produced via the…”

“…However, monitoring 3 He, as well as 6 Li, is important because these isotopes are strong thermal neutron absorbers and could potentially lead to degradation of the beryllium properties as a neutron reflector.…”

“…The isotopic production after 17 irradiation cycles * obtained with fluxes and cross sections from this model were compared with the isotopic production from the reference model that uses the standard Cycle 400 BOC concentrations of 6 Li and 3 He. FigureFig.…”

“…More recently, other studies estimated the amount of thermal poison buildup in the HFIR beryllium reflector in order to more accurately predict reactivity worth at startup after a long reactor shutdown period [6], [7]. The procedure used the ORIGEN module of the SCALE package [8] to estimate the total amount of 3 He and 6 Li produced in the reactor as a function of time.…”

“…The procedure used the ORIGEN module of the SCALE package [8] to estimate the total amount of 3 He and 6 Li produced in the reactor as a function of time.…”