Qualification and Uncertainty Evaluation of a Best Estimate Loca Study of the Mochovce NPP by RELAP5/3.2-Gamma and CIAU

The paper describes the work that has been done in cooperation between VUJE, Inc. (Slovakia) and University of Pisa (UNIPI, Italy). The aim was to evaluate Best Estimate Plus Uncertainty calculation (BEPU) of Mochovce Nuclear Power Plant WWER-440/213 (NPP) for the selected LOCA scenario utilizing the Code with the capability of Internal Assessment of Uncertainty (CIAU) developed at UNIPI. At the basis of CIAU, there is the Uncertainty Method based on Accuracy Extrapolation (UMAE) previously proposed by UNIPI. The project was considered as a full pilot BEPU application for WWER-440 type of unit in VUJE, Inc. that can be taken as a basis for utilization in licensing process later on. Project objectives are as follows: • To prove capability of available Mochovce NPP nodalization for RELAP5/3.2.2 gama to predict meaningful results for LOCA type accidents following UMAE procedure [1]. • To apply the CIAU [2, 3] to a LOCA transient selected for the Mochovce NPP and produce uncertainty bands for selected relevant parameters.