Deterministic uncertainty propagation methods are certainly powerful and time-sparing but their access to uncertainties related to the power map remains difficult due to a lack of numerical convergence. On the contrary, stochastic methods do not face such an issue and they enable a more rigorous access to uncertainty related to the PFNS. | A stochastic method to propagate uncertainties along large cores deterministic calculations EPJ Nuclear Sci. Technol. 4 12 2018 Nuclear Sciences L. Volat et al. published by EDP Sciences 2018 amp Technologies https epjn 2018015 Available online at https REGULAR ARTICLE A stochastic method to propagate uncertainties along large cores deterministic calculations Ludovic Volat Bernard Gastaldi and Alain Santamarina CEA DEN DER SPRC Cadarache 13108 Saint-Paul Les Durance Cedex France Received 10 November 2017 Received in final form 13 February 2018 Accepted 4 May 2018 Abstract. Deterministic uncertainty propagation methods are certainly powerful and time-sparing but their access to uncertainties related to the power map remains difficult due to a lack of numerical convergence. On the contrary stochastic methods do not face such an issue and they enable a more rigorous access to uncertainty related to the PFNS. Our method combines an innovative transport calculation chain and a stochastic way of propagating uncertainties on nuclear data first our calculation scheme consists in the calculation of assembly self-shielded cross sections and a pin-by-pin flux calculation on the whole core. Validation was done and the required CPU time is suitable to allow numerous calculations. Then we sample nuclear cross sections with consistent probability distribution functions with a correlated optimized Latin Hypercube Sampling. Finally we deduce the power map uncertainties from the study of the output response functions. We performed our study on the system described in the framework of the OECD NEA Expert Group in Uncertainty Analysis in Modelling. Results show the 238U inelastic scattering cross section the 235U PFNS the elastic scattering cross section of 1H and the 56Fe cross sections as major contributors to the total uncertainty on the power map the power tilt between central and peripheral assemblies using COMAC-V2 covariance library amounts to .
