Comprehensive evaluation of nuclear data library variations and TRISO distribution methods on neutronic properties of HTR-10 pebble-bed fuel using OpenMC

Abstract

The HTR-10 reactor requires highly complex modeling, particularly in pebble distribution within the core and TRISO particle distribution within the pebbles. This complexity significantly impacts the suitability of nuclear data library selection and the accuracy of model simplifications to enhance computational efficiency. While most related studies focused on k-eigenvalue calculations, they often overlooked depletion calculations, which were essential for determining reactor operational lifetime. This study comprehensively evaluated the impact of four nuclear data libraries (ENDF/B-VIII.0, ENDF/B-VII.1, JEFF-3.2, and JEFF-3.3) and three TRISO distribution methods (random lattice, hexagonal lattice, and rectangular lattice) on the neutronic characteristics of HTR-10 pebble-bed fuel, including k-eigenvalue, material depletion, and the dominant physical properties influencing these parameters. The results indicated that all four data libraries provided consistent criticality calculations, but significant differences were observed in material depletion, particularly between ENDF/B-VIII.0 and ENDF/B-VII.1, with relative difference remaining below 1.00 %. The geometric simplification aspect that was implemented resulted in a sixfold reduction in computation time for k-eigenvalue calculations and a 43-fold reduction for depletion calculations, without compromising accuracy or precision, maintaining differences below 1.00 % for k-eigen, material depletion, and other physical parameters. Notable discrepancies between simplified and random models were primarily observed in reaction rate distributions, yet these did not substantially affect total reaction rate calculations, with relative errors remaining under 1.5 × 10⁻³. These findings highlighted that simplifying TRISO distribution using hexagonal lattice and rectangular lattice significantly enhanced the efficiency of HTR-10 pebble-bed fuel analysis without causing significant deviations in accuracy or precision.