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Validation is the characterization of the suitability of a selected mathematical model and data to correctly predict and describe real-world physical phenomena. This places validation at the intersection of modeling, simulation, and experimental methods. ORNL has broad validation experience, including the collection and qualification of experimental validation data, leadership in international benchmark handbooks, development of problem-specific validation criteria, as well as comparison and visualization of large data sets.

ORNL experts participate in numerous international standards organizations, OECD/NEA, and IAEA expert groups, and other bodies that define validation standards and develop international benchmark databases. Our experts are available to partner with you to improve the validation basis for your tools in your application domains.

Because of their origins as NRC and industry licensing tools, ONRAMP neutronics tools such as SCALE and VERA are built on a robust validation basis. For SCALE, continuous-energy and multigroup neutronics data and tools are validated against 600 nuclear criticality experiments from the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and the International Reactor Physics Benchmark Evaluation Project (IRPhEP). The validation suite itself is maintained under a quality assurance and configuration management program known as the Verified, Archived Library of Inputs and Data (VALID). Burnup calculations are validated on a nuclide-specific basis, with over 100 post irradiation examination measurements of commercial reactor fuel from the Spent Fuel Composition (SFCOMPO) database. Decay heat calculations are validated against another suite of over 100 commercial reactor spent fuel assemblies whose heat generation rates were measured at the Swedish Central Interim Spent Fuel Storage Facility (Clab) assembly calorimeter. For short-term calculations of decay heat, burst fission measurement data experiments are used for validation.

The TSUNAMI S/U tools of SCALE are specifically designed to support advanced neutronics validation approaches and are routinely applied to quantify important aspects of application systems for validation, to identify the best available experimental data to apply, to combine experimental data from many sources to build a cumulative validation basis, and where validation gaps exist, to assign an appropriate safety margin or design a new, optimized experiment that could fill this gap in the future.

The VERA tools that implement the same nuclear data and physics foundations as SCALE build upon these validated results to create extended multiphysics capabilities. For validation of the integrated reactor analysis capabilities of VERA, data from operating power plants are applied, including startup criticality tests, boron letdown data, and detailed in-core flux maps. VERA has been validated with data from 16 reactors with over 100 operating cycles.