Patent Number: 
Section: claims

1. A safety valve drive system in which a safety valve of a nuclear power plant is opened by supplying a driving gas by using a pilot valve at an occurrence of an accident or a transient state occurs, thereby protecting a reactor against pressure application, the safety valve drive system comprising:a safety valve drive unit, as the safety valve actuating means, configured to actuate in a manner such that the safety valve is opened in response to respective auto-depressurization system actuating signals for two or more segments among respective auto-depressurization system actuating signals for four segments, and is configured to close by an auto-depressurization system actuating signal for one or less segments among the auto-depressurization system actuating signals for the four segments; andcables connected up the safety valve drive unit and configured to transfer the auto-depressurization system actuating signals for the four segments;wherein the safety valve drive unit comprises:an opening line provided for a gas supply line for safety valve opening operation;a pilot valve driving gas supply line configured to drive the pilot valve provided for the opening line so as to be closed when a pilot valve driving gas is supplied and to be opened when the pilot valve driving gas is not supplied; anda pilot valve driving circuit provided for the pilot valve driving gas supply line so as to supply the pilot valve driving gas to the pilot valve in response to respective actuating signals for two or more segments among the actuating signals for four segments, and not to supply the pilot valve driving gas to the pilot valve if an actuating signal for one or less segment among the actuating signals for the four segments is received. 2. The safety valve drive system according to claim 1, further comprising an accumulator provided for the pilot valve driving gas supply line in preparation for loss in functions of a pilot valve driving gas supply system. 3. A safety valve drive system in which a safety valve of a nuclear power plant is opened by supplying a driving gas by using a pilot valve at an occurrence of an accident or a transient state, thereby protecting a reactor against pressure application, the safety valve drive system comprising:a safety valve drive unit actuating unit, as safety valve actuating means: configured to actuate in such a manner that the safety valve is opened in response to respective relief valve pressure setpoint “high” actuating signals for two or more segments among respective relief valve pressure setpoint “high” actuating signals for four segments, and is closed state when a relief valve pressure setpoint “high” actuating signal for one or less segments among the relief valve pressure setpoint “high” actuating signals for the four segments is received; andcables connected to the safety valve drive unit and configured to transfer the relief valve pressure setpoint “high” actuating signals for the four segments;wherein the safety valve drive unit comprises:an opening line provided for a gas supply line for safety valve opening operation;a pilot valve driving gas supply line configured to drive the pilot valve provided for the opening line so as to be closed when a pilot valve driving gas is supplied and to be opened when the pilot valve driving gas is not supplied; anda pilot valve driving circuit provided for the pilot valve driving gas supply line so as to supply the pilot valve driving gas to the pilot valve in response to respective actuating signals for two or more segments among the actuating signals for four segments, and not to supply the pilot valve driving gas to the pilot valve if an actuating signal for one or less segment among the actuating signals for the four segments is received. 4. The safety valve drive system according to claim 3, wherein an accumulator is provided for in the pilot valve driving gas supply line in preparation for loss in functions of a pilot valve driving gas supply system. 5. A safety valve drive system in which a safety valve of a nuclear power plant is opened by supplying a driving gas by using a pilot valve at an occurrence of an accident or a transient state, thereby protecting a reactor against pressure application, the safety valve drive system comprising:a safety valve drive unit, as safety valve actuating means, configured to actuate in such a manner that the safety valve is opened in response to respective auto-depressurization system actuating signals for two or more segments among respective auto-depressurization system actuating signals for three segments, and is closed when an auto-depressurization system actuating signal for one or less segments among the auto-depressurization system actuating signals for the three segments is received; andcables connected to the safety valve drive unit and configured to transfer the auto-depressurization system actuating signals for the three segments;wherein the safety valve drive unit comprises:an opening line arranged in a gas supply line for safety valve opening operation;a pilot valve driving gas supply line configured to drive the pilot valve arranged in the opening line so as to be closed when a pilot valve driving gas is supplied and to be opened when the pilot valve driving gas is not supplied; anda pilot valve driving circuit provided for the pilot valve driving gas supply line so as to supply the pilot valve driving gas to the pilot valve in response to respective actuating signals for two or more segments among the actuating signals for the three segments, and not to supply the pilot valve driving gas to the pilot valve if an actuating signal for one or less segment among the actuating signals for the three segments is received. 6. The safety valve drive system according to claim 5, further comprising an accumulator provided for the pilot valve driving gas supply line in preparation for loss in functions of a pilot valve driving gas supply system.