IIST and LSTF counterpart test on PWR station blackout transient

A reduced-height, reduced-pressure (RHRP) integral system test facility at the Institute of Nuclear Energy Research (INER) has been established for simulating the thermal-hydraulics of a Westinghouse three-loop pressurized water reactor (PWR). To understand whether or not the physical phenomena observed in this RHRP integral system test facility during a station blackout (SB) transient can be reliably extrapolated to those for an actual plant, a counterpart test based on the same scenarios as those of the full-height, full-pressure (FHFP) large-scale test facility (LSTF) test was performed. To see the result of differences in the design, scaling approach and facility operational conditions in the systems, the present study examines their effects on the SB transient, particularly for the tests performed at full and reduced pressures. We also identify the occurrence of key thermal-hydraulic phenomena, as well as their possible distortions. Results of the INER integral system test (ISST) facility and LSTF tests showed the common thermal-hydraulic phenomena, such as the secondary coolant boil-off and the subsequent primary coolant saturation, pressurization, coolant inventory depletion and redistribution, and core uncovery caused by coolant boil-off. The sequence and timing of the significant events during the SB transient studied in the RHRP IIST facility are also consistent (in most cases) with those for the SB transient studied in the FHFP LSTF.