Simplification of multigroup cross-section processing for large depletion calculations in TRITON

TRITON is the primary lattice physics module of the SCALE code system. Initially developed under U.S. Nuclear Regulatory Commission funding for high-fidelity mixed-oxide fuel assembly analysis, TRITON is now being used internationally for a wide variety of applications. However, for large heterogeneous lattice configurations, the cross-section processing required to obtain appropriately weighted burnup-dependent cross sections can be a bottleneck in a calculation. To overcome this issue, two new approaches have been implemented to simplify the cross-section processing requirements for lattice depletion calculations in TRITON. Both approaches were implemented and tested within TRITON and found to result in very little loss of accuracy in the rigorous multigroup cross-section weighting available within SCALE. Results of an analysis of a 9 × 9 boiling-water-reactor lattice in which 41 independent depletion pin cells were tracked are presented. These results show that the simplified cross-section processing option in TRITON results in a substantial reduction in computational time with very little loss of accuracy. The capabilities described herein are available within the latest update to the Version 5.1 release of SCALE.