Investigation of Refilling Behaviour of a Simulated CANDO Feeder Pipe

Abstract

In order to enhance understanding and improve modelling of the refilling behaviour of CANDU feeder pipes under accident conditions, an experimental program has been initiated to study separate acts phenomena associated with diabatic conditions in a feeder. As part of this program a test loop has been designed and constructed with a vertical-to-horizontal test section containing a 90 degree elbow connected to a simulated header vesseL The simulated feeder test section is initially heated to about 3W C, and the coolant at different subcooling is injected into the feeder pipe though the header at different flow rates. Several scoping experiments have been performed and the results are presented in this report. The thermocouples spotwelded on the outside wall of the test section gave wall temperature histories and quenching data hm which several unique characteristics of the refilling process were identified. In particular, the elbow region was observed to quench immediately after the coolant injection began and the refilling process was initiated simultaneously in the vertical and horizontal sections. Furthermore, under low liquid subcooling conditions, some evidences of flooding in the horizontal section were observed resulting in a delay in the overall refilling rate.