About Power Error Estimation Using the Method of Uncertainty and Sensitivity Analysis for Verification of the Coupled Neutronic and Thermal Hydraulic Codes

Abstract

This paper describes the capability of sensitivity and uncertainty analysis (SUA) for estimation of power calculation error during the computer code verification compared to the data received in experiments at operating power plants. Estimation of errors in code verification calculation against measurements at operating plants and assessment of conservatism in safety calculations are considered as two interrelated problems. A defining moment in this approach is that one or more test cases are selected; selected test cases are included in matrix of code verification assuming that these test cases involve the same physical phenomena as in simulated accident scenarios. The criterion of test case “representativeness” is similarity between correlation coefficients of model predictions in accident scenario and test case. The example demonstrates how the SUA approach is used in calculations with the VVER-1000 coupled neutronic and thermal-hydraulic simulation model based on the KORSAR/GP and SAPFIR_95&RC_VVER codes.