Assessment of Modeling SBO Accident by MELCOR Code versus the Results of PSB-VVER Test Facility Using Fast Fourier Transform Based Method (FFTBM )

This paper deals with quantitative accuracy assessment of MELCOR code capability to predict Thermal-Hydraulic (TH) response of PSB-VVER Integral Test Facility (ITF) during Station Black-Out (SBO) accident. The PSB VVER is a full-height, 1:300 volume and power scale representation of a VVER-1000 nuclear power plant and has been widely used in validation of TH codes for VVER-1000 applications. A MELCOR nodalization has been developed for modeling SBO accident in PSB-VVER ITF and Fast Fourier Transform Based Method (FFTBM) method has been used to assess the code prediction with experimental data. The FFTBM has been widely applied to a number of comparisons involving separate and integral test facilities experiments. The FFTBM shows the measurement–prediction discrepancies (accuracy quantification) in the frequency domain. For accuracy quantification of MELCOR predictions for SBO accident, the FFTBM was applied to 28 selected TH variables. It is observed that there is a good agreement between MELCOR predictions and PSB-VVER measured data, and results of quantitative analysis are in acceptable range of quality for most of the parameters.