抄録
Series of slow transient and rapid blowdown calculations were performed to evaluate potential code problems for supercritical applications. The slow transients investigated transitions between sub-critical and supercritical pressures and temperatures. The rapid blowdown calculations simulated the geometry of the Edwards pipe experiment, but with supercritical initial conditions. Both series of calculations investigated a wide range of supercritical thermodynamic states. Overall, 20 of the 27 of the slow transient cases failed with the original code, and the probability of failure increased dramatically near the critical point. Eight of the 85 rapid blowdown calculations encountered water property failures and did not run to completion. The failures generally occurred near the critical point. Various code updates were implemented to correct the code execution failures. Changes were made to the reset water property derivatives at the critical point, the number of pressure and temperature points used to generate the steam tables near the critical point, the interpolations used for specific volume and isothermal compressibility, extrapolations for metastable states near the critical point, the interfacial heat transfer coefficient for vapor near the critical point, and to the transport properties. The modified code was able to successfully execute all of the slow transients and rapid blowdowns. In addition, the modified code was able to successfully execute a loss-of-coolant accident in a light water reactor pressurized to supercritical conditions.
