Auxiliary feedwater line automatically isolation method

The present invention belongs to the nuclear power plant control technology, in particular to a SGTR accident conditions auxiliary feedwater line automatically isolation methods can be used. The method of adding auxiliary feedwater isolation valves on each steam generator auxiliary feedwater piping, auxiliary feedwater isolation valves controlled by the control system; in the event of a steam generator tube rupture accident, according to the high steam generator level setpoint using corresponding steam generator "steam generator level high" and "low-low water level regulator," joint action trigger this signal corresponding line of the steam generator auxiliary feedwater isolation valve is closed, isolating the corresponding pipeline ruptured steam generator the auxiliary feedwater, steam generator to ensure that rupture does not occur overflowing; while blocking other steam generator isolation signal to other auxiliary steam generator feedwater is not affected, in order to ensure adequate core cooling water away heat. The present invention can improve the level of safety and effectiveness of plant operation of the auxiliary feedwater system.