Evaluation of the Scaling of the APEX-1000 Test Facility to AP1000 for Design Basis Events

The AP1000 is a 1000 MWe advanced nuclear power plant that uses passive safety features to enhance plant safety and to provide significant and measurable improvements in plant simplification, reliability, investment protection and plant costs. The AP1000 relies heavily on the 600 MWe AP600 which received design certification in 1999. A critical part of the AP600 design certification process involved the testing of the passive safety systems. A one-fourth height, one-fourth pressure test facility, APEX-600, was constructed at the Oregon State University to study design basis events, and to provide a body of data to be used to validate the computer models used to analyze the AP600. This facility was extensively modified to reflect the design changes for AP1000 including higher power in the electrically heated rods representing the reactor core, and changes in the size of the pressurizer, core makeup tanks and automatic depressurization system. Several design basis events have been simulated at APEX-1000 including double-ended direct vessel injection (DEDVI) line break, 2-inch cold leg break, and inadvertent actuation of the automatic depressurization system. These events were analyzed as part of the AP1000 safety analysis using the NOTRUMP computer code. Applying the scaling factors that were used to sizemore » the APEX-1000 facility, the test results can be compared to the NOTRUMP plant simulations. These comparisons indicate the similarity between the design basis events in AP1000 and APEX-1000, the adequacy of the scaling of APEX-1000, and the applicability of the NOTRUMP code. (authors)« less