Experiments to investigate DCH phenomena with large-scale models of the Zion and Surry nuclear power plants Original Research Article

The Surtsey Test Facility and the Containment Technology Test Facility (CTTF) at Sandia National Laboratories (SNL) have been used to perform scaled experiments for the Nuclear Regulatory Commission (NRC) that simulate high-pressure melt ejection (HPME) accidents in a nuclear power plant (NPP). These experiments are designed to investigate the effects of direct containment heating (DCH) phenomena on the containment load. High-temperature, chemically reactive alumino (thermitic) melt is ejected by high-pressure steam into a scale model of either the Zion or Surry NPP. Integral effects tests under prototypic conditions have been performed to investigate the effects of dispersal of molten core materials on DCH loads, and to study the effects of Westinghouse plant configurations on DCH loads. In Westinghouse plants, there is (1) an intermediate compartment that is large compared with the reactor cavity but small compared with the main containment volume, and (2) no significant line-of-sight pathway for debris transport from the cavity to the main containment volume. Containment compartmentalization is the dominant mitigating feature for Zion, Surry, and most other pressurized water reactors. Experimental results will be used to further assess the applicability of existing DCH models to Westinghouse plants on DCH loads.