Uncertainty Quantitative Analysis of Subchannel Code Calculation of PSBT Void Distribution Benchmark

Abstract

In order to evaluate the accuracy and reliability of the subchannel code, it is necessary to quantitatively give the uncertainty of the calculation results. The uncertainty analysis is conducted by using the statistical method based on propagation of input uncertainties, and the uncertainty range of the subchannel code calculation results can be obtained quantitatively. Based on the assumption that the uncertainty of model parameters obeys normal distribution, the statistical method is used to determine the distribution of the uncertainty of model parameters to replace the traditional expert judgment. Through the calculation of the pressurized water reactor sub-channel and bundle tests (PSBT) benchmark, the ability of the subchannel code COBRA-IV to predict the experimental results is analyzed, and the uncertainty interval satisfying the tolerance limit of the calculation results is obtained. The results demonstrate that the experiment data is well enveloped by the obtained uncertainty bands and the model calibrated by the statistical mean value presents a good improvement of calculations.

Keywords

• uncertainty quantification
• subchannel code
• void fraction