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Validating nuclear data uncertainties obtained from a statistical analysis of experimental data with the “Physical Uncertainty Bounds” method

Concerns within the nuclear data community led to substantial increases of Neutron Data Standards (NDS) uncertainties from its previous to the current version. For example, those associated with the NDS reference cross section 239Pu(n,f) increased from 0.6–1.6% to 1.3–1.7% from 0.1–20 MeV. | Validating nuclear data uncertainties obtained from a statistical analysis of experimental data with the Physical Uncertainty Bounds method EPJ Nuclear Sci. Technol. 6 19 2020 Nuclear Sciences c D. Neudecker et al. published by EDP Sciences 2020 amp Technologies https doi.org 10.1051 epjn 2020007 Available online at https www.epj-n.org REGULAR ARTICLE Validating nuclear data uncertainties obtained from a statistical analysis of experimental data with the Physical Uncertainty Bounds method Denise Neudecker Morgan Curtis White Diane Elizabeth Vaughan and Gowri Srinivasan Los Alamos National Laboratory P.O. Box 1663 MS-P365 Los Alamos NM 87545 USA Received 19 July 2019 Received in final form 25 January 2020 Accepted 12 February 2020 Abstract. Concerns within the nuclear data community led to substantial increases of Neutron Data Stan- dards NDS uncertainties from its previous to the current version. For example those associated with the NDS reference cross section 239 Pu n f increased from 0.6 1.6 to 1.3 1.7 from 0.1 20 MeV. These cross sections among others were adopted e.g. by ENDF B-VII.1 previous NDS and ENDF B-VIII.0 current NDS . There has been a strong desire to be able to validate these increases based on objective criteria given their impact on our understanding of various application uncertainties. Here the Physical Uncertainty Bounds method PUBs by Vaughan et al. is applied to validate evaluated uncertainties obtained by a statistical anal- ysis of experimental data. We investigate with PUBs whether ENDF B-VII.1 or ENDF B-VIII.0 239 Pu n f cross-section uncertainties are more realistic given the information content used for the actual evaluation. It is shown that the associated conservative 1.5 1.8 and minimal realistic 1.1 1.3 uncertainty bounds obtained by PUBs enclose ENDF B-VIII.0 uncertainties and indicate that ENDF B-VII.1 uncertainties are underestimated. 1 Introduction an evaluated uncertainty is not a physical quantity and there is no notion of .