DYNAMIC-RESPONSE OF HOT COLD LIQUID INTERFACES TO PUMP SPEED PERTURBATIONS IN A THERMAL-HYDRAULIC LOOP SIMULATING A PIUS-TYPE REACTOR/

The operation of a PIUS-type reactor requires controlling the reactor pump speed to keep stationary the hot/cold liquid interfaces between t he reactor coolant and cold berated water. The dynamic response of the interface location to pump speed perturbations is analyzed for an exp erimental loop simulating a PIUS-type reactor. The transfer function b etween the pump speed and the interface location is obtained by pertur bing and Laplace-transforming the one-dimensional fluid momentum equat ions. The analytical results agree well with experimental data taken f rom the same facility. It is shown that the magnitude of the phase lag in the response of the interface location, which needs to be consider ed in designing a pump speed controller, primarily depends on the flui d inertia in the loop, the density lock flow area, and the density dif ference between the simulated reactor coolant and berated water.