b'Figure 1. MCNP rendition of the ATR core and ARCTIC concept in the NE flux trapapproaches by using an off-the-shelfAccomplishments: fuel assembly as the booster fuel. ThisThis project included brainstorming, concept has been termed the Advancedcategorization, and prioritization fast Reactor Concept in Thermal-spec- of several concepts for specimen trum Irradiation Capability (ARCTIC).types and flux/spectra modification These studies used modern modelingschemes. These options were then to investigate the hypothesis thatinvestigated by predictive models. ARCTIC would result in a worthwhileA detailed Monte Carlo N-Participle fast flux increase whose deployment in(MCNP) model was constructed ATR would be timely in maturing fast(Figure 1) for the favored concept spectrum research while the commu- where an existing fuel assembly nity awaits availability of a true fastdesign in production for the Belgium spectrum test reactor. Reactor -2 (BR2) was placed in an ATR flux trap to boost fast flux to a 2021|AFC ACCOMPLISHMENTS 129'