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NEA SFR subassembly benchmark sensitivity/uncertainty propagation with depletion

Abstract : For the next generation of fast reactors, global objectives are required in terms of safety improvement, sustainability, waste minimization and non-proliferation. Concerning safety issues, particular efforts have been made in order to obtain core designs that can be resilient to accidental transients. Under the auspices of the Working Party on Scientific Issues of Reactor Systems (WPRS) an OECD/Nuclear Energy Agency (NEA) Expert Group Task Force on Uncertainty Analysis in Best-Estimate Modelling (UAM) for Design, Operation and Safety Analysis of Sodium-cooled Fast Reactors (SFR-UAM) has been initiated in 2015 with the objective to study the uncertainties in different stages of the next generation Sodium Fast Reactors. Among the identified topics of this expert group, a representative SFR fuel subassembly depletion benchmark has been set up in order to analyse the reactivity swing as well as the associated uncertainty level based on available nuclear data variance/covariance matrices coming from evaluations. The benchmark focuses on changes on number densities, on Doppler Effect and sodium void worth as well as kinetic parameters from the beginning of equilibrium cycle up to the end of cycle. For sensitivity/uncertainty estimation, two methods are tested a deterministic one based on sensitivities and a stochastic one using direct nuclear data sampling. In the deterministic approach, Boltzmann and Bateman equations are coupled at the sensitivity level with the help of the perturbation theory. This coupling is currently operational in ERANOS code system. The present implementation gives sensitivities for both reactivity coefficients and mass balance. For stochastic approach, relevant nuclear data set are directly sampled from variance/covariance data and used as input parameter for neutronic calculations. Both methods are found to be consistent.
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Submitted on : Monday, December 9, 2019 - 3:15:18 PM
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  • HAL Id : cea-02400194, version 1




L. Buiron, G. Rimpault. NEA SFR subassembly benchmark sensitivity/uncertainty propagation with depletion. BEPU 2018 (ANS Best Estimate Plus Uncertainty International Conference), May 2019, Lucca, Italy. ⟨cea-02400194⟩



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