Flow oscillation simulation with CATHENA

Flow oscillations may occur in some postulated accident events in CANDU 6 reactors, which may influence the timing of reactor trip and occurrence of fuel sheath dryout. Therefore an accurate prediction of the characteristics of the flow oscillations is necessary from a reactor trip coverage perspective. Flow oscillations in the heat transport system of CANDU 6 reactor due to a single pump trip have been predicted by different codes. However, the predicted results are not always consistent. To make certain that CATHENA code is capable of predicting flow oscillations in some postulated accidents events, a commissioning test performed at Point Lepreau Generating Station in 1983 is simulated using CATHENA Plant Model. The simulation results indicate that CATHENA code is able to capture the characteristics of the oscillations caused by initial perturbation of the heat transport system though the amplitude of the oscillation is much smaller than that cause by single pump trip. The sensitivity of the results to the maximum time step is also examined. This simulation of a reactor commissioning test may provide confidence in the capability of CATHENA in simulating flow oscillation phenomena. (author)