Regular Article

How to obtain an enhanced extended uncertainty associated with decay heat calculations of industrial PWRs using the DARWIN2.3 package

¹ CEA, DEN, DER Cadarache, 13108 Saint Paul-lez-Durance, France
² EDF Research and Development, 7 Boulevard Gaspard Monge, 91120 Palaiseau, France
³ Aix Marseille Univ., Université de Toulon, CNRS, IM2NP, Marseille, France

^* e-mail: jordan.huyghe@cea.fr

Received: 27 June 2018
Received in final form: 20 December 2018
Accepted: 27 March 2019
Published online: 29 July 2019

Abstract

Decay heat is a crucial issue for in-core safety after reactor shutdown and the back-end cycle. An accurate computation of its value has been carried out at the CEA within the framework of the DARWIN2.3 package. The DARWIN2.3 package benefits from a Verification, Validation and Uncertainty Quantification (VVUQ) process. The VVUQ ensures that the parameters of interest computed with the DARWIN2.3 package have been validated over measurements and that biases and uncertainties have been quantified for a particular domain. For the parameter “decay heat”, there are few integral experiments available to ensure the experimental validation over the whole range of parameters needed to cover the French reactor infrastructure (fissile content, burnup, fuel, cooling time). The experimental validation currently covers PWR UOX fuels for cooling times only between 45 minutes and 42 days, and between 13 and 23 years. Therefore, the uncertainty quantification step is of paramount importance in order to increase the reliability and accuracy of decay heat calculations. This paper focuses on the strategy that could be used to resolve this issue with the complement and the exploitation of the DARWIN2.3 experimental validation.