Methods for Design, Evaluation, and Analysis of the 1/4 Scale Water RCCS at Wisconsin
The Reactor Cavity Cooling System (RCCS) is a key safety system in the design of the gas-cooled Next Generation Nuclear Plant (NGNP). Developed under the auspices of the DOE Generation IV program, the RCCS must accommodate limiting accident scenarios by successfully removing decay heat from the reactor pressure vessel. To evaluate the heat removal performance and stability bounds of the RCCS design, a scaled experimental facility has been constructed at the University of Wisconsin – Madison, modeling a 5° sector and 1/4 axial extent of a full scale, water cooled concept prototype.
A diverse set of instrumentation has been incorporated into the facility, serving as a guide for experimental practices and providing measurement of key thermal hydraulic data including water temperatures, pressure drop, mass fluxes, and void fractions. Meeting the project goals presented unique challenges that required balancing prototypic design constraints and practical considerations for an experimental facility. An overview of the design approach and solution methods are presented, which employed the use of tools such as MATLAB, ANSYS, RELAP5, and FLUENT. Results are first presented from a series of experiments at single phase steady-state conditions, which establish linearity and performance bounds and provide baseline data sets for comparison to computer codes. Then, results from testing at two-phase saturation are presented that characterize the magnitude and behavior of flow oscillations at varying power levels.