The Rig-of-Safety Assessment (ROSA)-III Program conducted a 200% recirculation pump-suction line break test, RUN 903, simulating a loss-of-coolant accident (LOCA) in a boiling water reactor (BWR). In this test, the main recirculation pumps (MRPs) were continuously operated during the transient following the break to study the influence of increased core flow rate on the system responses. This report describes major thermal-hydraulic phenomena observed in this test and presents all the experiment data. The effects of prolonged pump operation on system responses are described in comparison with the results of standard 200% break test, RUN 926, in which the core flow coasted down after the break faster than a scaled BWR LOCA condition. It is shown that the significant core heatup observed during the early blow-down phase in RUN 926 was not observed in RUN 903 due to an additional mass transport (approximately 6% of the initial system mass) from the downcomer into the core shroud as a result of the prolonged pump operation. It is clear that the lower-than-scaled transient core flow rate in the ROSA-III tests significantly affected the core thermal conditions especially during the early blowdown phase. (author).