Experimental Studies of Reflooding in Horizontal Fuel Channels

Abstract

This paper describes the result of the experimental studies on reflooding in horizontal fuel channels. The experiments were performed in order to understand the thermohydraulic behaviour in horizontal fuel channels following a loss-of-coolant accident (LOCA) in the CANDU reactor. The basic reflooding behaviour in a horizontal fuel channel was made clear by the single-channel reflooding experiments. It was shown as a result of the multichannel reflooding tests that the flow resistance of feeders in the outlet side, particularly that of the orifice in the inZet feeder in the event of a reactor inlet-side break, is an important factor affecting flow distribution among the channels and that it appears to be very important to properly determine the discharge-depressurization characteristics of the accumulator to reflood all the channels within a short enough time to avoid unacceptable sheath overheating. In addition, the threshold of flow stratification under conditions expected during reflooding was experimentally obtained.