Expansion of the ORNL VALID Library

The Verified Archived Library of Inputs and Data (VALID) maintained at Oak Ridge National Laboratory contains high-quality, independently reviewed models and results that are used in SCALE validation and testing. Most of the contents of VALID are models of evaluated critical benchmarks from the International Criticality Safety Benchmark Evaluation Project (ICSBEP) Handbook. The criticality safety validation of SCALE 6.2.2 used the models from VALID, which included 618 individual critical configurations covering 15 ICSBEP experiment categories. Ongoing benchmark intercomparison studies being performed under the auspices of the US Department of Energy Nuclear Criticality Safety Program have shown that VALID must be expanded to provide more common experiments with other participating institutions. Interest in uranium enriched to between 5 and 20 wt % ²³⁵U for advanced reactors is also driving expansion of VALID to enhance coverage of this enrichment range. This engagement of multiple sponsors representing different user communities has driven a broad program to increase the depth and breadth of VALID. At this writing, 138 additional configurations have completed the review process, including systems fueled with highly enriched uranium, intermediate enriched uranium (IEU), low enriched uranium (LEU), and plutonium. Fissile forms in this set include metal, solution, and compound. Fast, intermediate, and thermal spectrum systems are all also included in the new configurations. These additional models also include deuterium- and polyethylene-moderated systems, in addition to the light-water moderated systems already being added to VALID. Additionally, 139 more configurations are currently in the review process. These expansion efforts will continue in the future.