Analysis of refill behaviour in CANDU-type feeders

By analyzing the feeder-surface temperature and channel differential-pressure measurements in these experiments, a detailed picture of the quench and refill processes in a feeder has been obtained. The extended time delay associated with feeder refill can be split into two components: a feeder-quenching time delay and a feeder complete-refill time delay. It is concluded that the rate of feeder quenching is limited by countercurrent flow flooding in the feeders, whereas the rate of feeder complete refill is controlled by the hydrostatic pressure imbalance between the inlet and outlet feeders. The progress of the quench front through the feeder pipework is observed to be nonuniform. It takes more time to quench some feeder sections (referred to as critical feeder sections) than others. A possible explanation is presented to account for this observation. The influence of parallel channels on feeder refill is also described. (orig./DG)