Quantitative accuracy evaluation of small break LOCA Counterpart Tests performed in LOBI, SPES, BETHSY and LSTF Facilities

An experimental data base relevant to scaling in nuclear thermal-hydraulics was created prior to this report. The Integral Test Facilities (ITF) considered are LOBI, BETHSY, SPES and LSTF. The same Small Break Loss of Coolant Accident (SBLOCA) accident scenario was measured in the four facilities. However six experiments were performed because in each of LOBI and SPES ITF two test were carried out. The former (in each case) was the ‘low’ initial power consistent with the power in the two ITF, the latter (in each case) was the ‘high’ initial power exploiting the capabilities of both SPES and LOBI (in terms of maximum scaled power available). The gathered database includes three main parts: • Geometrical and material configuration of ITF • Boundary and initial conditions for the 6 experiments • Selected time trends (about 50) during the experiments The database constitutes a milestone achievement for the demonstration of thermal-hydraulic system code capabilities addressing the scaling issue. A database of calculations for each experiment (e.g. comparing experimental data with calculated results for each test – noticeably part of the ‘virtual’ Counterpart Test [CT] international program - ) was created prior to this report. In this report the Fast Fourier Transform Based Method (FFTBM) was applied to the evaluation of the comparison between experimental data and calculated results. The FFTBM application allowed the confirmation that quality of all calculations was adequate, thus allowing, among the other things, the use of UMAE (uncertainty method) for calculating the error in the prediction of the same (CT-SBLOCA) scenario in a Nuclear Power Plant.