JP5696056B2 - Reactor isolation cooling system - Google Patents

Description

  The present invention relates to a reactor isolation cooling device, and more particularly to a reactor isolation cooling device suitable for application to a boiling water nuclear power plant.

  In a boiling water nuclear power plant, a nuclear reactor is surrounded by a reactor containment vessel, and a pressure suppression chamber is formed in the reactor containment vessel. In this boiling water nuclear power plant, even when the reactor is shut down with all control rods inserted into the reactor, decay heat of several percent of the rated power is generated in the reactor core. In a boiling water nuclear power plant in operation, if for some reason all control rods are inserted into the reactor core and the operation of the boiling water nuclear power plant is stopped, the main steam pipe connected to the nuclear reactor The provided main steam isolation valve is fully closed, and the steam generated in the core due to the decay heat of the nuclear fuel material is released into the cooling water in the reactor pressure suppression chamber from the relief safety valve provided in the main steam pipe. This release of steam results in a drop in the water level in the reactor.

  For this reason, the reactor isolation cooling system that removes the decay heat generated in the reactor core when the control rods are fully inserted into the reactor core and the reactor is isolated suppresses the decrease in the reactor water level described above. It is used to In the reactor isolation cooling system, steam generated by the decay heat of nuclear fuel material is introduced from the reactor into the heat transfer tube installed in the fuselage fuselage, and this steam is present outside the heat transfer tube in the fuselage. This system removes heat by exchanging heat with cooling water. The condensed water produced by the condensation of steam in the heat transfer tube is returned to the reactor pressure vessel.

  An example of a reactor isolation cooling device is described in Japanese Patent Application Laid-Open No. 4-27896. This reactor isolation cooling device is provided with a cooling water storage tank provided with a heat transfer tube inside, a steam pipe connected to the reactor pressure vessel connected to the inlet side of the heat transfer tube, and an outlet side of the heat transfer tube The connected condensate piping is connected to the reactor pressure vessel, and the condensate piping is provided with a flow control valve. When a reactor isolation event occurs, steam generated by decay heat in the reactor pressure vessel is led to the heat transfer tube through the steam pipe to condense, and the generated condensed water passes into the reactor pressure vessel through the condensate pipe. Returned. At this time, the control device that has input the measured reactor pressure adjusts the opening of the flow control valve to adjust the amount of condensed water returned into the reactor pressure vessel. For this reason, when an isolation event occurs, the pressure drop in the reactor pressure vessel is suppressed, and this pressure is kept constant.

  Further, a reactor isolation cooling apparatus described in Japanese Patent Laid-Open No. 3-246492 has a condenser arranged in a pool filled with cooling water, and steam is connected to one end of a heat transfer tube of the condenser. A pipe is connected to the reactor pressure vessel, and the other end of the heat transfer tube is connected to the reactor pressure vessel through a condensate pipe. A first isolation valve is provided in the steam pipe and a third isolation valve is provided in the condensate pipe. The first bypass pipe provided with the second isolation valve bypasses the first isolation valve and is connected to the steam pipe. The second bypass pipe provided with the fourth isolation valve bypasses the third isolation valve and is connected to the condensate pipe. When starting the reactor isolation cooling device, the second and fourth isolation valves are opened, and the first and third isolation valves are opened after the time required for warming up the condenser has elapsed. In this way, the condenser is warmed up. The temperature in the reactor pressure vessel after the reactor isolation cooling device is started is controlled by adjusting the opening of each of the second and fourth isolation valves or adjusting the opening of each of the first and third isolation valves. Is done. In addition, each opening degree of a 1st isolation valve, a 2nd isolation valve, a 3rd isolation valve, and a 4th isolation valve is controlled by the control apparatus.

JP-A-4-27896 JP-A-3-246492

  In the reactor isolation cooling device described in Japanese Patent Application Laid-Open No. 4-27896, when a power loss occurs at the time of reactor isolation, the flow control valve provided in the condensate pipe cannot be opened. As a result, at the time of reactor isolation, the reactor cannot be cooled by the reactor isolation cooling device.

  An object of the present invention is to provide a reactor isolation cooling device that can cool a reactor even when a power loss occurs at the time of reactor isolation.

  A feature of the present invention that achieves the above-described object is that a condenser having a heat transfer tube, a steam supply pipe that is connected to the inlet of the heat transfer pipe and guides the steam generated in the reactor pressure vessel to the heat transfer pipe, and A condensed water return pipe that leads the condensed water discharged from the heat transfer pipe connected to the outlet of the heat pipe to the reactor pressure vessel, a first opening / closing valve that is provided in the condensed water return pipe and opens when the reactor is isolated, and a first opening / closing A bypass pipe having both ends connected to the condensed water return pipe by bypassing the valve and a second on-off valve provided in the bypass pipe and opened when the power is lost are provided.

  Bypassing the first open / close valve and connecting the condensate return pipe with the bypass on / off valve, which opens when the power is lost, opens the first open / close valve when power is lost during reactor isolation. Even when it is not possible, the second on-off valve can be opened. Thereby, the condensed water produced by the condensation of steam in the heat transfer tube of the condenser can be guided to the reactor pressure vessel through the bypass pipe, and the reactor can be cooled.

  According to the present invention, it is possible to cool a nuclear reactor even if a power loss occurs during the isolation of the nuclear reactor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of a reactor isolation cooling apparatus according to embodiment 1, which is a preferred embodiment of the present invention. It is a block diagram of the valve actuator which operates the bypass valve shown in FIG. 1 at the time of power loss. It is a block diagram of the bypass valve used for the reactor isolation | separation cooling device of Example 2 which is another Example of this invention.

  Examples of the present invention will be described below.

  A reactor isolation cooling apparatus according to embodiment 1, which is a preferred embodiment of the present invention, will be described with reference to FIGS.

  The reactor isolation cooling device 3 of the present embodiment will be described with reference to FIG. The reactor isolation cooling device 3 is applied to a boiling water nuclear power plant. This boiling water nuclear power plant has a reactor pressure vessel 1 in which a core 2 is built. A pressure gauge 13 and a water level gauge 14 are installed in the reactor pressure vessel 1. The pressure gauge 13 and the water level gauge 14 are connected to the operation signal generator 15.

  The reactor isolation cooling device 3 includes a condenser 4 having a heat transfer pipe 5 installed in the fuselage, a steam supply pipe 8, a condensed water return pipe 9, a condensate valve 10, a control device 11, a bypass pipe 16, and a bypass valve 17. And a valve actuator 27. A steam supply pipe 8 connected to the reactor pressure vessel 1 is connected to an inlet portion of the heat transfer pipe 5 of the condenser 4. The position of the opening of the steam supply pipe 8 in the reactor pressure vessel 1 is located above the liquid level of the cooling water formed in the reactor pressure vessel 1 during normal operation of the boiling water nuclear power plant. Yes. A condensed water return pipe 9 connected to the outlet of the heat transfer pipe 7 is connected to the reactor pressure vessel 1. The position of the opening of the condensed water return pipe 9 in the reactor pressure vessel 1 is located below the liquid level of the cooling water formed in the reactor pressure vessel 1 during normal operation of the boiling water nuclear power plant. ing. A condensate valve 10, which is an electric valve, is provided in the condensed water return pipe 9. A bypass pipe 16 provided with a bypass valve (open / close valve) 17 bypasses the condensate valve 10 and is connected to the condensed water return pipe 9. A flow restriction orifice (flow restriction device) 18 is attached to the bypass pipe 16.

  As shown in FIG. 2, the bypass valve 17 includes a cylinder 19, a piston 20, and a valve body 21. The piston 21 is disposed in the cylinder 19 and the valve body 21 is connected to the piston 20 with a rod. Cylinder chambers 22 and 23 are formed in the cylinder 19. The cylinder chamber 23 is formed closer to the valve body 21 than the piston 20, and the cylinder chamber 22 is formed on the opposite side of the valve body 21 with respect to the piston 20.

  The valve actuator 27 has trip valves 24 and 25 and a solenoid valve 26. Trip valves 24 and 25 are air operated valves. A of the trip valve 24 is connected to the cylinder 19 by a pipe 36 and communicated with the cylinder chamber 22. P of the trip valve 24 is connected to the volume tank 32 by a pipe 38. A pipe 37 connected to the cylinder 19 and connected to the cylinder chamber 23 is connected to A of the trip valve 25. E of the trip valve 25 is connected to the pipe 38 by the pipe 39. P of the trip valve 25 is connected to an instrument air source 28 by a pipe 31. A check valve 29 is provided in the pipe 31.

  A pipe 40 for supplying driving air to the trip valve 24 is connected to A of the electromagnetic valve 26. A pipe 41 that supplies driving air to the trip valve 25 is connected to the pipe 40. A pipe 30 connected to P of the electromagnetic valve 26 is connected to the pipe 31 between the check valve 29 and the instrumentation air source 28. The E of the trip valve 24 and the E of the electromagnetic valve 26 are not connected anywhere. A power supply 12 is connected to the control device 11 and the electromagnetic valve 26. An operation signal generator 15 is also connected to the control device 11.

  During normal operation of the boiling water nuclear power plant, the condensate valve 10 is closed, and the steam generated in the reactor pressure vessel 1 is prevented from flowing into the condenser 4 of the cooling device 3 during reactor isolation. Has been.

  The water level in the reactor pressure vessel 1 is measured by the water level gauge 14, and the pressure in the reactor pressure vessel 1 is measured by the pressure gauge 13. The measured water level and pressure are input to the operation signal generator 15. When the pressure measured by the pressure gauge 13 becomes equal to or higher than the set pressure, or when the water level measured by the water level gauge 14 becomes equal to or lower than the set water level, an operation signal is output from the operation signal generator 15 to the control device 11. Is done. The control device 11 to which the operation signal output from the operation signal generator 15 is input opens the condensate valve 10. When the condensate valve 10 is opened, the reactor isolation cooling device 3 is activated. That is, the reactor isolation cooling device 3 is activated during the reactor isolation. In addition, when the measured pressure exceeds the set pressure during the operation of the boiling water nuclear power plant, or when the measured water level falls below the set water level, all control rods are inserted into the reactor core and boil The operation of the water nuclear plant is stopped, and a main steam isolation valve (not shown) provided in a main steam pipe (not shown) connected to the reactor pressure vessel 1 is closed.

  When the operation of the boiling water nuclear power plant is stopped, the steam generated by the decay heat of the nuclear fuel material in the core in the reactor pressure vessel 1 is opened when the condensate valve 10 is opened at the time of reactor isolation. It is led into the heat transfer pipe 5 of the condenser 4 through the steam supply pipe 8. The opening degree of the condensing valve 10 is adjusted by a control device 11 to which current is supplied from a power source 12. The steam in the heat transfer tube 5 is condensed by the water 6 existing in the body of the condenser 4 outside the heat transfer tube 5 to become condensed water 7. The condensed water 7 is discharged from the heat transfer pipe 5 into the condensed water return pipe 9. When the power source 12 is normal, the condensed water 7 is guided into the reactor pressure vessel 1 through the condensed water return pipe 9, and the core 2 is cooled by the condensed water 7.

  When the power supply 12 is in a normal state and the condensing valve 10 is open, the bypass valve 17 is closed. The closing operation of the bypass valve 17 when the power supply 12 is in a normal state will be described. When the power supply 12 is in a normal state, current is supplied from the power supply 12 to the electromagnetic valve 26, so the electromagnetic valve 26 opens A and P and closes E. For this reason, the pressurized air from which the air from the instrumentation air source 28 has reached the electromagnetic valve 26 via the pipes 31 and 30 is discharged to the pipe 40 through P and A of the electromagnetic valve 26, and the trip valve 24. A part of the pressurized air discharged to the pipe 40 is supplied to the trip valve 25 through the pipe 41. In each of the trip valves 24 and 25, A and P are opened by the action of pressurized air, and E is closed. For this reason, the pressurized air in the volume tank 32 is supplied to the cylinder chamber 22 through the pipe 41, P and A of the trip valve 24, and the pipe 36. An instrument air source 28 is communicated with the cylinder chamber 23 through the pipe 31, P and A of the trip valve 25, and the pipe 37. Since the pressure of the pressurized air in the volume tank 32 is higher than the pressure of the pressurized air of the instrumentation air source 28, the piston 20 moves toward the cylinder chamber 23, and the bypass pipe 16 is the valve body 21 of the bypass valve 17. Closed by.

  If the operation of the boiling water nuclear plant is stopped and the power supply 12 is lost, the condensing valve 10 is closed. When the power source 12 is lost, that is, when no current is supplied from the power source 12 to the solenoid valve 26, the solenoid valve 26 is opened by A and E and P is closed. For this reason, the pressurized air of the instrumentation air source 28, which is the driving air for the trip valves 24, 25, is not supplied to the trip valves 24, 25 from the electromagnetic valve 26, respectively. A and E are opened and P is closed. Pressurized air in the volume tank 32 is supplied to the cylinder chamber 23 through the pipes 38 and 39, the E and A of the trip valve 25, and the pipe 37. The pressurized air in the cylinder chamber 22 is exhausted to the outside through the pipe 36 and the trip valves 24 A and E. For this reason, the piston 20 moves to the cylinder chamber 22 side and lifts the valve body 21. The bypass valve 17 is opened.

  In the present embodiment, as described above, when the reactor is isolated, the bypass valve 17 is opened even if the power source is lost. Therefore, the reactor 2 is generated by the decay heat of the nuclear fuel material in the core 2 in the reactor pressure vessel 1. The steam thus condensed is condensed in the heat transfer tube 5 of the condenser 4 as described above. The condensed water 7 generated by the condensation of the steam is discharged to the condensed water return pipe 9 and guided to the reactor pressure vessel 1 through the bypass pipe 16.

  In the present embodiment, when the reactor is isolated in a state where current is supplied from the power source 12 to the control device 11, the condensate valve 10 is opened by the control device 11, so that the core in the reactor pressure vessel 1 is opened. 2, the steam generated by the decay heat of the nuclear fuel material can be condensed in the heat transfer tube 5 of the condenser 4. The generated condensed water 7 is guided into the reactor pressure vessel 1 through the condensate valve 10. In this way, when current is supplied from the power supply 12, the condensate valve 10 can be opened to cool the nuclear reactor.

  When the power source is lost at the time of reactor isolation, the condensing valve 10 is fully closed, and the bypass valve 17 can be opened by the valve operating device 27 as described above. For this reason, the steam generated by the decay heat of the nuclear fuel material in the reactor core 2 at the time of reactor isolation is condensed in the heat transfer pipe 5, and the generated condensed water 7 is condensed water return pipe 9, bypass pipe 16 and condensed water return pipe 9. Are sequentially led into the reactor pressure vessel 1 to cool the reactor. At this time, the condensed water 7 does not pass through the condensate valve 10. Further, since the condensed water 7 is guided into the reactor pressure vessel 1, the water level in the reactor pressure vessel 1 does not substantially change.

  A flow rate restriction orifice 18 provided in the bypass pipe 16 limits the flow rate of the condensed water 7 guided to the reactor pressure vessel 1. That is, the flow restriction orifice 18 restricts the condensed water 7 from flowing into the reactor pressure vessel 1 excessively. For this reason, it can prevent that the temperature decreasing rate in the reactor pressure vessel 1 becomes larger than a limit value. When current is supplied from the power supply 12, the opening of the condensate valve 10 is adjusted, the flow rate of the condensed water 7 guided to the reactor pressure vessel 1 is adjusted, and the temperature reduction rate in the reactor pressure vessel 1 is limited. It can prevent becoming larger than the value. Since the opening degree of the bypass valve 17 cannot be adjusted when the power source is lost, the flow rate of the condensed water 7 guided to the reactor pressure vessel 1 is limited by the flow rate restriction orifice 18.

  A reactor isolation cooling apparatus according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIG.

  The reactor isolation cooling device of the present embodiment is configured by replacing the bypass valve 17 with the bypass valve 17A in the reactor isolation cooling device 3 of the first embodiment. By using the bypass valve 17A, the valve operating device 27 used in the first embodiment becomes unnecessary. Other configurations of the reactor isolation cooling device of the present embodiment are the same as those of the reactor isolation cooling device 3 of the first embodiment.

  The detailed structure of the bypass valve 17A used in the present embodiment will be described below. The bypass valve 17 </ b> A includes an iron core 36, an electromagnetic coil 33, a spring (compression spring) 34, and a valve body 21. The iron core 36, the electromagnetic coil 33, and the spring 34 are installed in the case. The valve body 21 is attached to a rod that is attached to the iron core 36 and penetrates the case. The electromagnetic coil 33 surrounds the iron core 32. The spring 34 is attached to the case and supports the iron core 32. The electromagnetic coil 33 is connected to a power source 35.

  When the power source is not lost at the time of reactor isolation, a current is supplied from the power source 35 to the electromagnetic coil 33 to excite the electromagnetic coil 33. The iron core 32 is attracted downward by excitation of the electromagnetic coil 33, and the bypass pipe 16 is blocked by the valve body 21. In the present embodiment, the steam generated by the decay heat of the nuclear fuel material in the core 2 is condensed in the heat transfer tube 5 of the condenser 4 at the time of the nuclear reactor isolation. When the power source is not lost, the condensate valve 10 is opened as in the first embodiment, so that the condensed water 7 generated in the heat transfer pipe 5 is not the bypass pipe 16 but the condensed water return pipe 9. It is led through the reactor pressure vessel 1. Even during normal operation of the nuclear power plant, the electromagnetic coil 33 is excited and the iron core 32 is attracted downward by the excitation of the electromagnetic coil 33, and the bypass pipe 16 is sealed by the valve body 21.

  When power is lost during reactor isolation, the condensate valve 10 remains closed. Since no current is supplied from the power source 35 to the electromagnetic coil 33 of the bypass valve 17 </ b> A, the electromagnetic coil 33 is not excited and the iron core 32 is pushed upward by the spring 34. The valve body 21 is pulled upward, and the bypass valve 17A is opened. At this time, the condensed water 7 generated in the heat transfer tube 5 is led into the reactor pressure vessel 1 through the bypass pipe 16 and the core 2 is cooled.

  In the present embodiment, each effect produced in the first embodiment can be obtained. Further, since the bypass pipe 17A that is released when the power source is lost is provided in the bypass pipe 16, the valve operating device 27 is not necessary in this embodiment, and the configuration is more than that of the reactor isolation cooling device 3 of the first embodiment. Simplified.

  DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel, 2 ... Reactor core, 3 ... Reactor cooling system, 4 ... Condenser, 5 ... Heat transfer pipe, 8 ... Steam supply pipe, 9 ... Condensate return pipe, 10 ... Condensate valve, DESCRIPTION OF SYMBOLS 11 ... Control apparatus, 10 ... Water level gauge, 11 ... Steam supply pipe, 13 ... Pressure gauge, 14 ... Water level gauge, 15 ... Actuation signal generator, 16 ... Bypass piping, 17, 17A ... Bypass valve, 18 ... Flow restriction orifice , 19 ... cylinder, 20 ... piston, 21 ... valve body, 24, 25 ... trip valve, 26 ... solenoid valve, 27 ... valve actuator, 32 ... iron core, 33 ... electromagnetic coil, 34 ... spring.

Claims (6)

  A condenser having a heat transfer tube, a steam supply pipe connected to the inlet of the heat transfer pipe to guide the steam generated in the reactor pressure vessel to the heat transfer pipe, and an outlet of the heat transfer pipe connected to the heat transfer pipe. A condensed water return pipe for guiding the condensed water discharged from the heat pipe to the reactor pressure vessel, a first opening / closing valve provided in the condensed water return pipe and opening when the reactor is isolated; bypassing the first opening / closing valve; A reactor isolation isolation cooling device comprising: a bypass pipe having both ends connected to the condensed water return pipe; and a second on-off valve provided in the bypass pipe and opened when power is lost.   The reactor isolation cooling device according to claim 1, wherein the first on-off valve is an electric valve.   The reactor isolation cooling device according to claim 1 or 2, wherein a flow rate limiting device for limiting a flow rate of the condensed water led into the reactor pressure vessel is provided in the bypass pipe.   The reactor isolation cooling device according to claim 3, wherein the flow restriction device is a flow restriction orifice. The second on-off valve is an air operated valve, and the air operated valve has a cylinder and a piston disposed in the cylinder and connected to the valve body,
The cylinder is connected to a first cylinder chamber formed on the valve body side of the piston in the cylinder, and the first working air is supplied to the first cylinder chamber and the first working air is supplied from the first cylinder chamber. A first trip valve for discharging, connected to a second cylinder chamber formed in the cylinder in a direction farther from the valve body than the piston, and supplying the first working air to the second cylinder chamber and the second A valve operating device having a second trip valve that discharges the first operating air from a two-cylinder chamber, and an electromagnetic valve that controls the supply of the second operating air to each of the first and second trip valves. When the current is supplied to the solenoid valve, the first and second trip valves are controlled so that the pressure in the second cylinder chamber is higher than the pressure in the first cylinder chamber, 2. The valve operating device for controlling the first and second trip valves so that a pressure in the first cylinder chamber is higher than a pressure in the second cylinder chamber when no current is supplied to the magnetic valve. 5. The reactor isolation cooling device according to any one of items 1 to 4. The second on-off valve, a spring for moving iron core connected to the valve body, the core when the supply of current to the electromagnetic coil及beauty before Symbol electromagnetic coil is interrupted surrounding the core in a direction away from the bypass pipe It claims 1 to have a to the reactor core isolation cooling system according to any one of 4.

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