Regular Article

Impact of correlations between core configurations for the evaluation of nuclear data uncertainty propagation for reactivity

¹ CEA, Reactor Studies Department, Reactor Physics and Fuel Cycle Division, 13108 Saint Paul-Lez-Durance, France
² CEA, Reactor Studies Department, Experimental Physics Division, 13108 Saint Paul-Lez-Durance, France

^⁎ e-mail: Thomas.frosio@gmail.com

Received: 2 April 2016
Received in final form: 11 May 2016
Accepted: 25 November 2016
Published online: 8 March 2017

Abstract

The precise estimation of Pearsons correlations, also called “representativity” coefficients, between core configurations is a fundamental quantity for properly assessing the nuclear data (ND) uncertainties propagation on integral parameters such as k-eff, power distributions, or reactivity coefficients. In this paper, a traditional adjoint method is used to propagate ND uncertainty on reactivity and reactivity coefficients and estimate correlations between different states of the core. We show that neglecting those correlations induces a loss of information in the final uncertainty. We also show that using approximate values of Pearson does not lead to an important error of the model. This calculation is made for reactivity at the beginning of life and can be extended to other parameters during depletion calculations.