An experimental investigation of BWR/4 long-term cooling with either intact or broken jet pumps

Experiments simulating emergency core cooling (ECC) conditions after a hypothetical design basis loss-of-coolant-accident (LOCA) in a 218-BWR/4, for either intact or broken jet pump seals, were performed at RPI in a special parallel channel effects (PCE) test section in which Freon-114 was used as the working fluid. The experimental results show that, as expected, core uncovery occurs first in the cold channels. These data were shown to agree with the results of an analytical drift-flux model, and indicate that broken jet pump seals can lead to early core uncovery, and may have a determinal effect on the long-term cooling of a BWR/4. Moreover, it was found that breaks in the lower seal are far more detrimental than a breach of the throat-to-diffuser slip joint. (orig.)