[en] This report documents a study of an accident sequence in boiling water reactor (BWR) in which there is a large reactivity insertion due to the flushing of borated water from the core. This has the potential to occur during an anticipated transient without scram (ATWS) after the injection of borated water from the standby liquid control system. The boron shuts down the power, but if there is a rapid depressurization of the vessel (e.g., due to the inadvertent actuation of the automatic depressurization system), large amounts of low pressure, relatively cold, unborated water enters the vessel causing a rapid dilution and cooling. This study was carried out to determine if the reactivity addition caused by this flushing could lead to a power excursion sufficient to cause catastrophic fuel damage. Calculations were carried out using the RELAP5/MOD2 computer code under different assumptions regarding timing and availability of low pressure pumps and with different reactivity coefficients. The results showed that the fuel enthalpy rise was insufficient to cause catastrophic fuel damage although less severe fuel damage might still be possible due to the overheating of the fuel cladding. 10 refs., 13 figs., 5 tabs