COMECO experiments on molten pool coolability in BWR lower head

A new series of experiments on the COMECO (COrium MElt COolability) test facility were carried out at the Nuclear Power Safety Division of the Royal Institute of Technology, Stockholm. During the experiments the molten pools were quenched by establishing a water layer above the melt pool. The aim of the experiments was to investigate the additional melt coolability capacity, offered by the presence of a large number of the Control Rod Guide Tubes (CRGT's) in the lower head of the Reactor Pressure Vessel (RPV) of BWR type reactors. The CRGT's offer a rather high Coolability potential, since there is a large number of these tubes in the lower head, with each of them offering a substantial additional heat transfer area. Also, additional coolant could be supplied to the RPV via the guide tubes. The primary objective of the experimental program was to obtain data on the heat removal capacity, offered by CRGT's in the melt pool with temperatures of up to 1100 .deg. C. This paper summarizes the experimental results along with related analysis