Burn-cycle-dependent spatial distribution of nuclear fuel actinides and fission products based on the AGENT code

Abstract

BRITTS (Burnup of Reactor Isotopes, Tracking in Time and Space) is a newly developed burnup module based on the Runge-Kutta 4th order method supplementing the well-known AGENT neutronics code. Unlike other burnup codes that are limited to 2D models, cumulative-only calculations, or one specific fuel type, BRITTS provides detailed spatial distributions of actinides in 2D and approximate 3D (through a 2D/1D coupled characteristic solution provided by the AGENT code) at user-specified points in a burn cycle. Using two simple MOX fuel pins, BRITTS is compared with SCALE6.2. BRITTS is also compared against a well-known OECD/NEA benchmark of UO2 fuel pin with 16 participants. These comparisons show that BRITTS provides reliable calculations for concentrations of nuclear fuel actinides and fission products in both 2D and approximate 3D and can be uniquely used to analyze the spatial distributions of the actinides during the burn-cycles. This paper presents the mathematical and numerical methods employed in BRITTS and a series of benchmark examples showing the code capabilities for reactor fuel analyses.