Method for determining core flow rate and water temperature/density in

Abstract

A method for determining the core flow rate from pump differential pressure method equations and a heat balance equation for determining the temperature and density of the reactor water in the downcomer and lower plenum region. The measured reactor water temperature is used only as an initial estimate for this new method. This allows the first estimate of the core flow to be determined based upon the reactor water density that corresponds to this temperature and the pump differential pressure and pump rotational speed measurements. Then, with this intial core flow measurement value, and other available plant measurements and assumed nominal values for the heat balance equation, revised values for the reactor water temperature and density can be calculated. Using a standard numerical method, such as the successive approximation technique, a more accurate estimate for the reactor water density can be obtained. A more accurate value for the core flow can be determined by the pump differential pressure method core flow equation using this more accurate density estimate. The iterative process is continued until tightly converged values for the calculated core flow and calculated reactor water temperature and density are obtained. By this approach, the overall accuracy of the calculated reactor core flow and the reactor water temperature/density is improved.