Nuclear Data for Criticality Safety: Past Insights and Future Directions

Around the world, nuclear data is used in radiation transport codes for criticality calculations. Because these calculations often determine criticality safety margins for operations involving special nuclear material, it is quintessential that the data are of the highest quality. The United States nuclear data library, Evaluated Nuclear Data File Version B (ENDF/B), is maintained, updated, extended, verified, and validated by the Cross Section Evaluation Working Group (CSEWG), which is a well-established group made up of members from national laboratories, industry, and universities. The process of improving nuclear data, commonly referred to as traversing the nuclear data pipeline, often involves numerous steps and support from multiple organizations. New public releases of ENDF/B are dependent on individuals successfully completing this process for many nuclides. The latest version of ENDF/B, ENDF/B-VIII.1, was formally released to the public last year. The ENDF/B-VIII.1 nuclear data library has files that have incorporated significant updates to major actinides and nuclides in moderators, reflectors, and structural materials. In this work, the nuclear data pipeline is briefly outlined, evaluated nuclear data file changes from some of the past ENDF/B version releases that could have significant impact on criticality safety applications are discussed, and future work for nuclear data investigation is proposed.