Quantification and propagation of neutronics uncertainties of the Kozloduy-6 VVER-1000 fuel assembly using SCALE 6.2.1 within the NEA/OECD benchmark for uncertainty analysis in modelling of LWRs

Abstract

This work is based on the benchmark for uncertainty analysis in modelling of light water reactors compiled by the Nuclear Energy Agency within the Organisation for Economic Cooperation and Development (OECD/NEA). The objective of the benchmark is to determine and verify uncertainty bounds for results of calculations of LWRs based on operating data using best-estimate codes. The main contribution of this paper is the quantification of uncertainties in the Kozloduy-6 VVER-1000 fuel assembly using SCALE-6.2.1 methodology. The benchmark consists of three phases, each with three exercises. Three reactor systems are also studied, viz. the PWR, VVER and BWR reactors. In this study, Phase I of the benchmark was considered for the uncertainty quantification. The sources of uncertainties are classified into three groups, namely uncertainties due to nuclear data, manufacturing tolerances and numerical uncertainties due to methods’ implementations. The calculations are carried out using KENO-VI to perform the neutronics calculations and TSUNAMI-2D/3D and SAMPLER to perform the sensitivity and uncertainty analysis. Nuclear data uncertainty has been identified to be the highest contributor of uncertainty of the VVER-1000 fuel assembly. Although this is true, the uncertainty due to other parameters must always be considered together with nuclear data, since some of them could be significant