Implementation of Uncertainty Propagation in TRITON/KENO

BACKGROUND Monte Carlo methods are beginning to be used for three- dimensional fuel depletion analyses to compute various quantities of interest, including isotopic compositions of used nuclear fuel. The TRITON control module, available in the SCALE 5.1 code system, can perform three-dimensional (3-D) depletion calcula- tions using either the KENO V.a or KENO-VI Monte Carlo trans- port codes, as well as the two-dimensional (2-D) NEWT discrete ordinates code. To overcome problems such as spatially non- uniform neutron flux and non-uniform statistical uncertainties in computed reaction rates and to improve the fidelity of calculations using Monte Carlo methods, uncertainty propagation is needed for depletion calculations. RESEARCH OBJECTIVES AND METHODS To enhance and expand the proper/ informed use of Monte Carlo methods for 3-D depletion analyses, statistical uncer- tainty propagation will be developed and implemented in the TRITON/KENO se- quence of SCALE. In particular, work will focus on development and implementation of an approach to determine the uncer- tainty in isotopic predictions based on the compound effects of multiple calculations (depletion time steps) with stochastic un- certainties in the spatial fluxes in each time step. Subsequently, an evaluation of the statistical uncertainties for an actual commercial used fuel sample will be per- formed to verify the implementation and develop a better understanding of the im- portance of statistical uncertainties in the prediction of isotopic compositions.