Thermal Hydraulics of LOFT Large Break Experiments and its Simulations with DRUFAN-02

Abstract

Several large break experiments were conducted in the Loss-of-Fluid Test (LOFT) facility in Idaho. The LOFT pressurized water reactor (PWR) was a fully operation, 50 MW (t) facility and was related to a commercial PWR through volumetric scaling principles. The main phenomena observed during large break LOCE (Loss of Coolant Experiments) are analysed. Most of the measurements were reproducible and so it was easy to identify the phenomena. Four large break LOCE are discussed in detail with special attention to early rewet and the influence of pump behavior on such a phenomenon. Other phenomena in connection with the exit flow, intact loop behavior and Emergency Core Coolant Injection (ECCI) are analysed. The thermal hydraulic code DRUFAN-02 was used for pre-test and post-test calculation of these experiment. Good agreement between measured and calculated thermal hydraulic parameters such as a system pressure, exit flow and fluid density was found. Differences between measured and calculated cladding temperatures are mainly due to multidimensional effects.