ATWS mitigation for a BWR-2

One major concern during an isolation ATWS event from power operation is the need to reduce reactor power as early as possible in order to minimize suppression pool heatup via relief valve blowdown and thus increase the time available to shut the reactor down. A means of accomplishing this for a BWR-2 during ATWS conditions is to trip the recirculation pumps and initiate isolation condensers automatically on high system pressure and then intentionally allow the core power generation and system coolant inventory to reach equilibrium by manual termination of feedwater. The results using the RELAP5/MOD1 code for Main Steam Isolation Valve Closure and Loss of Feedwater ATWS events, show that core power is reduced to a value approximately equal to that of the emergency condenser steam relief capacity while core cooling is maintained and suppression pool heatup is minimized