Non-intrusive simultaneous calculation of nuclear data sensitivity and uncertainty of core simulator parameters for the full-scale Krško NPP core model

Malec, Jan (author), Fiorito, Luca (author), Grimaldi, Federico (author), Trkov, Andrej (author)

We present a framework for propagating uncertainties from nuclear data to integral parameters of the Krško PWR core design calculations and for calculating their sensitivity profiles to nuclear data. This non-intrusive method is intended for multi-step calculations using codes where nuclear data sensitivity capabilities based on adjoint calculation are not available. In our approach, incident neutron reaction cross-sections and $\overline{ν}$ are randomly sampled based on covariance information in the source evaluated nuclear data files and perturbed core design calculations are run. The uncertainties of the critical boron concentration, of the axial difference in relative power and of their change in the reactor cycle are calculated as the standard deviation of the core design output runs. A linear regression framework is designed to compute sensitivity profiles from the nuclear data perturbations used for uncertainty propagation. After validation against the results of the Serpent Monte Carlo code for the TMI pincell criticality benchmark, we calculated the propagated uncertainty of $^{235}$U, $^{238}$U, $^{16}$O, $^{56}$Fe and $^{239}$Pu to the selected reactor core parameters and the sensitivity of the Krško critical boron concentration at hot zero power to the fission cross section of $^{235}$U. The contribution of individual nuclides to the overall uncertainties was estimated with first-order Sobol indices.

• Language: English
• Keywords: sensitivity, uncertainty, nuclear core simulator, SANDY, linear regression, stochastic sampling
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 7 str.
• Numbering: Vol. 189, art. 105892
• PID: 20.500.12556/RUL-182551
• UDC: 539.1
• ISSN on article: 0149-1970
• DOI: 10.1016/j.pnucene.2025.105892
• COBISS.SI-ID: 241446659
• Publication date in RUL: 15.05.2026

Record is a part of a journal

• Title: Progress in nuclear energy
• Shortened title: Prog. nucl. energy
• Publisher: Elsevier
• ISSN: 0149-1970
• COBISS.SI-ID: 2627111

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: jedrska fizika, simulatorji, modeli

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0073
• Name: Reaktorska fizika