Abstract
A computational model of the reactor core of the High Flux Isotope Rector (HFIR) was developed
in order to analyze non-destructive accidents caused by transients during reactor operation. Such a
model was built based on the available description parameters as provided by the latest version of
the nuclear analysis software package called Program for the Analysis of Reactor Transients
(PARET). Analysis performed with the model constructed was compared with previous data
obtained with other tools in order to benchmark the code. Finally, the model was used to analyze
the behavior of the reactor under transients using a different nuclear fuel with lower enrichment of
uranium (LEU) than the fuel currently used, which has a high enrichment of uranium (HEU). The
study shows that the presence of fertile isotopes in LEU fuel which increases the neutron
resonance absorption reduces the impact of transients on the fuel and enhances the negative
reactivity feedback, thus making LEU fuel a safe alternative fuel for the reactor core.