Dynamic system characterization of an integral test facility of an advanced PWR

Abstract

This work characterizes the dynamic behavior for the modified Large Scale Test Facility (LSTF), which has been selected by the U.S. Nuclear Regulatory Commission for confirmatory testing of the Westinghouse AP600 design. The LSTF is performing a series of tests to generate data for code assessment against AP600 relevant phenomena. The AP600 design relies only on passive safety features such as gravity driven draining pressurized tanks, and battery power logic and actuators for its safety functions. The inclusion of Core Makeup Tanks and passive heat removal systems into the design increase its dynamic complexity well beyond that of any conventional pressurized water reactor, in which the safeties can be treated as imposed boundary conditions. The bond graph methodology was used to formulate the equations and their topology, as they are used to characterize such a complex system. This characterization was applied to one of the Rig of Safety Assessment (ROSA) program transients, the one-inch cold leg break (AP-CL-03), to construct a mathematical model of the system. The model's constitutive equations were linearized for a selected period of the transient that is of particular importance to the safety analysis. These equations were used for the linear analysis of the system.