Control apparatus for residual heat removal system for nuclear reactor

Claim 1

An apparatus for controlling a residual heat removal system for a nuclear reactor, comprising a reactor housed in a containment vessel; a main steam conduit for leading reactor steam to a turbine for generating electric power, said main steam conduit having isolation valves near said containment vessel; and a residual heat removal system to be started upon closure of said isolation valves to remove residual heat out of said reactor, said residual heat removal system including a closed loop having a heat exchanger for condensing steam generated in said reactor into water and a pump for pressurizing the condensed water sent thereto through a first control valve and for supplying said pressurized water into said reactor, and an auxiliary turbine actuated by reactor steam sent thereto through a second control valve so as to drive said pump, wherein a tank for containing make-up water therein, a check valve inserted in a make-up water pipe for supplying said make-up water to the outlet of said first control valve, a make-up water control apparatus for controlling said first control valve according to the lowering of the level of the reactor water after the closure of said isolation valves so as to lower the pressure at the outlet of said first control valve, and a feedwater flow control apparatus for determining the aperture of said second control valve in accordance with the deviation signal representing the difference between the temperature fall rate in said reactor and a desired value for said rate are further provided and wherein said make-up water control apparatus supplies make-up water into said reactor to compensate the lowered level of the reactor water when the pressure at the outlet of said control valve falls below the pressure to open said check valve while the feedwater flow is controlled by said feedwater flow control apparatus in accordance with said desired value for said rate so as to control the water level to the initial level.

Claim 2

An apparatus for controlling a residual heat removal system for a nuclear reactor, comprising a reactor housed in a containment vessel; a main steam conduit for leading reactor steam to a turbine for generating electric power, said main steam conduit having isolation valves near said containment vessel; and a residual heat removal system to be started upon closure of said isolation valves to remove residual heat out of said reactor, said residual heat removal system including a closed loop having a heat exchanger for condensing steam generated in said reactor into water and a pump for pressurizing the condensed water sent thereto through a first control valve and for supplying said pressurized water into said reactor, and an auxiliary turbine actuated by reactor steam sent thereto through a second control valve so as to drive said pump, wherein a tank for containing make-up water therein, a check valve inserted in a make-up water pipe for supplying said make-up water to the outlet of said first control valve, a make-up water control apparatus for controlling said first control valve according to the lowering of the level of the reactor water after the closure of said isolation valves so as to lower the pressure at the outlet of said first control valve, and a feedwater flow control apparatus for determining the aperture of said second control valve in accordance with the deviation signal representing the difference between the temperature fall rate in said reactor and a desired value for said rate are further provided and wherein said make-up water control apparatus supplies make-up water into said reactor to compensate the lowered level of the reactor water when the pressure at the outlet of said control valve falls below the pressure to open said check valve while the feedwater flow is controlled by said feedwater flow control apparatus in accordance with said desired value for said rate so as to control the water level to the initial level.

Claim 4

An apparatus for controlling a residual heat removal system for a nuclear reactor, comprising a reactor housed in a containment vessel; a main steam conduit for leading reactor steam to a turbine for generating electric power, said main steam conduit having isolation valves near said containment vessel; and a residual heat removal system to be started upon closure of said isolation valves to remove residual heat out of said reactor, said residual heat removal system including a closed loop having a heat exchanger for condensing steam generated in said reactor into water and a pump for pressurizing the condensed water sent thereto through a first control valve and for supplying said pressurized water into said reactor, and an auxiliary turbine actuated by reactor steam sent thereto through a second control valve so as to drive said pump wherein a feedwater flow control apparatus is further provided which determines the aperture of said second control valve in accordance with the deviation signal representing the difference between the temperature fall rate in said reactor and a desired value for said temperature fall rate.

Claim 5

An apparatus for controlling a residual heat removal system for a nuclear reactor, comprising a reactor housed in a containment vessel; a main steam conduit for leading reactor steam to a turbine for generating electric power, said main steam conduit having isolation valves near said containment vessel; and a residual heat removal system to be started upon closure of said isolation valves to remove residual heat out of said reactor, said residual heat removal system including a closed loop having a heat exchanger for condensing steam generated in said reactor into water and a pump for pressurizing the condensed water sent thereto through a first control valve and for supplying said pressurized water into said reactor, and an auxiliary turbine actuated by reactor steam sent thereto through a second control valve so as to drive said pump wherein a feedwater flow control apparatus is further provided which determines the aperture of said second control valve in accordance with the deviation signal representing the difference between the temperature fall rate in said reactor and a desired value for said temperature fall rate.