[en] The effectiveness of the core spray-cooling system (CSCS) and the low-pressure-coolant-injection (LPI) system during a design-basis accident (DBA) in a boiling-water nuclear reactor (BWR) was investigated. This investigation considered a BWR/4 with both intact and broken jet pumps during the short-term and long-term core cooling of a postulated loss-of-coolant accident (LOCA). The experiments were performed in a special parallel channel effects (PCE) test section in which Freon-114 was used to simulate the conditions in a BWR/4. The PCE test section simulated the major regions of a BWR/4, namely: three heated parallel channels; a bypass channel; a bypass-to-channel leakage path; a jet pump; lower and upper plena; a steam separator and standpipe; and a downcomer. Extensive use of glass components in the PCE test section provided visual observation of the thermal-hydraulic phenomena