Modeling space–time evolution of flux in a traveling wave reactor

• Monte-Carlo MCNPX was used to analyze flux profile in a traveling wave reactor.
• Results show steady propagation of flux (2 cm/year) over life of the reactor.
• High discharge burn-up of 394 GWd/MTU was observed for the prototype compact model.

Simulations have been carried out using Monte Carlo code MCNPX to evaluate the space and time evolution of flux in a prototype traveling wave reactor under constant thermal power condition. A 3-D box-shaped model of the reactor is developed. The reactor core is divided into two primary regions: the smaller, enriched region with fissile material; and the larger non-enriched region with fertile material. This enrichment strategy is aimed to allow breed-and-burn in the core. The core, on the outside, is surrounded by shielding material of uniform thickness. To facilitate the study, these two primary regions in the core are further divided into thin slab-like regions referred to as cells. Results show propagation of flux profile from the enriched region to the non-enriched region at a near constant speed. Analyses of time evolution of local power density (power fraction) at specified locations in the core are presented. Space and time evolution of the overall core burn-up and localized burn-up are discussed.