This paper deals with liquid film dryout and rewetting behavior under BWR (Boiling Water Reactor) transient condition. The rewetting behavior has not been fully clarified. Therefore, the transient BT (Boiling Transition) tests were performed using a simulated BWR 4×4 rod bundle which many thermocouples were installed along one of the heater rod in order to clarify the re-wetting behavior.
The following results were obtained;
(1) The BT occurs initially just upstream of the spacer. The location of BT then propagates upstream, and finallyrewetting occurs upstream between adjacent spacers.
(2) The liquid film front exists between spacers.
(3) Rewetting propagation velocity decreases, as wall superheat increases.
