JPS6137593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nuclear power plant system.

Taking a boiling water nuclear power plant as an example, a condensate storage tank is used as a water source for surplus water conditioning and cooling systems. This will be explained below with reference to the attached drawings.

FIG. 1 is a schematic diagram showing the flow of water around a conventional boiling water nuclear power plant.

A large number of control rod drive devices 26 are provided at the bottom of the reactor pressure vessel 1, and a reactor containment vessel 2 is installed surrounding the reactor pressure vessel 1. A partition wall 3 is provided that divides the inside of the reactor containment vessel 2 into an upper reactor well 4a and a lower dry well 4b. A pressure suppression pool 5 is provided below the outside of the reactor containment vessel 2, and a reactor building 6 is provided surrounding it. A turbine building (not shown) installed outside the reactor building 6 is equipped with a turbine 7, a main condenser 8, etc., and is connected to the reactor pressure vessel 1 through valves 10a, 10b, and 10c. and are connected by a main steam pipe 9. A pipe 11 is provided from upstream of the valve 10b via a valve 12, bypassing the turbine 7, and connecting to the main condenser 8. This main condenser 8 communicates with the turbine 7, and further includes a condensate pump 13, a purifier 14, a boost pump 16a, a feed water heater 15, and a feed water pump 16.
b. It is connected to the reactor pressure vessel 1 by a water supply pipe 19 via a feed water heater 17 and a valve 18, respectively. Further, a condensate storage tank 20 containing condensate is communicated with the water supply pipe 19 through a piping 21, and is also connected to the main condenser 8 through a makeup water pump 22 through a piping 23. This condensate storage tank 20 is connected to the control rod drive device 26 through a pipe 27a that connects the control rod drive pump 24 and the water pressure control unit 25, and its return pipe 27b.
It is also connected via a hydraulic control unit 25 to a waste treatment device 28 having a drain pipe to a pit 29 and further connected to a condensate storage tank 20 by a pipe 30. The reactor pressure vessel 1 includes a recirculation pump 31 and piping 32 for forcibly circulating the reactor core flow rate.
A recirculation system consisting of the following is provided within the reactor containment vessel 2. The mechanical seal portion of this recirculation pump 31 is connected to the waste treatment device 2 via piping 33.
8 is connected. On the other hand, pressure suppression pool 5
is connected to the pipe 3 via the emergency cooling pump 34 and the valve 35.
6 to the reactor pressure vessel 1.
Further, a pipe 37 communicating with the condensate storage tank 20 is connected to the suction side pipe of the emergency cooling pump 34 to constitute an emergency core cooling system. Reactor building 6
A fuel storage pool 38 and a skimmer surge tank 39 connected to the fuel storage pool 38 are provided in the inner upper part.
A pump 40, a heat exchanger 41, a purification device 42, and a pipe 43 connecting the reactor well 4a constitute a fuel storage pool cooling and purification system.
Further, a pipe communicating with the skimmer surge tank 39 and the reactor well 4a is connected to the main condenser 8 by a pipe 44.

The operation will be explained below. Steam generated in the reactor pressure vessel 1 is sent to the turbine 7 through the main steam pipe 9, rotates the turbine 7, and is condensed in the main condenser 8. In some cases, the water passes through a pipe 11 that bypasses the turbine 7 and is condensed in the main condenser 8. The condensed water is sent to condensate pump 1
After being pressurized in Step 3 and purified in the purification device 14, a portion is returned to the condensate storage tank 20 through the pipe 21,
The remaining water is heated by feed water heaters 15 and 17, pressurized by booster pump 16a and feed water pump 16b, and returned to reactor pressure vessel 1 through water feed pipe 19. Further, the control rod drive device 26 provided at the bottom of the reactor pressure vessel 1 is cooled by water in the condensate storage tank 20 during normal reactor operation. This water flows into the reactor pressure vessel 1 through the control rod drive device 26 . Further, during a scram of the reactor, the waste water from the control rod drive device 26 is sent to the waste treatment device 28. In addition, the staging flow rate from the mechanical seal part of the recirculation pump 31 that forcibly circulates the coolant inside the reactor is also sent to the waste treatment device 28, where this water is purified and stored as condensate for reuse. The remaining water is returned to the tank 20, but the remaining water is discharged to the pit 29 and taken out of the plant.

When replenishing water to the main condenser 8, the replenishment water pump 22 replenishes the water in the condensate storage tank 20, and in order to replenish the condensate storage tank 20 with water, there is a A system (not shown) is provided.

In addition, the fuel storage pool cooling and purification system is equipped with a heat exchanger 4.
1. The purification device 42 removes decay heat from the spent fuel and purifies the pool water.

Furthermore, pool water is stored in the pressure suppression pool 5, which absorbs the energy of the high-temperature, high-pressure coolant that would be released in the event of a primary system piping rupture accident, and also increases the pressure with the emergency cooling pump 34 to cool the reactor core in an emergency. It functions as a water source for injecting into the reactor pressure vessel 1. The water in the condensate storage tank 20 also functions as this water source.

However, this pressure suppression pool 5 water is rarely used except in the event of a loss of coolant accident as mentioned above, and is used for periodic inspections of turbine-driven pump operation, equipment and piping when the cooling system is activated during reactor shutdown. Reactor water containing radioactive materials flows in and accumulates due to warm-up of the reactor, subsequent pump tests, activation of the relief safety valve (not shown) of the main steam pipe 9, etc., and if this continues for a long period of time, the pressure suppression pool 5 and the surrounding area may increase the dose rate. Therefore equipment,
If water is injected into the reactor pressure vessel 1 during repair of piping or when the emergency core cooling system is activated, there is a risk that the reactor internal structures will also be adversely affected.

The object of the present invention is to have a device for purifying pressure suppression pool water, and to organically combine or share this device with an existing system to obtain a rationalized nuclear power plant.

FIG. 2 is a schematic system diagram showing an embodiment of a nuclear power plant according to the present invention. The same parts as in FIG. 1 will be described with the same reference numerals.

A reactor containment vessel 1 is provided surrounding a reactor pressure vessel 1 having a number of control rod drive devices 26 provided at its bottom. A partition wall 3 is provided that divides the inside of the reactor containment vessel 2 into an upper reactor well 4a and a lower dry well 4b. A pressure suppression pool 5 is provided outside the reactor containment vessel 2, and a reactor building 6 is provided surrounding it. A turbine building (not shown) provided outside the reactor building 6 is provided with a turbine 7 and a main condenser 8.
It is connected by main steam piping 9 via b and 10c. A pipe 11 is provided from upstream of the 10b, which bypasses the turbine 7 and is connected to the main condenser 8 via a valve 12. This main condenser 8 communicates with the turbine 7, and further connects a water supply pipe through a condensate pump 13, a purifier 14, a boost pump 16a, a feedwater heater 15, a feedwater pump 16b, a feedwater heater 17, and a valve 18, respectively. 19 is connected to the reactor pressure vessel 1 as in the conventional case. The pressure suppression pool 5 is connected to the control rod drive device 26 through a pipe 27a that connects the control rod drive pump 24 and the water pressure control unit 25, and the return pipe 27b is also connected to the pit 29 via the water pressure control unit 25. Waste treatment equipment 2 with drain pipe
8 and further connected to the pipe 5 via a pump 53.
4 to a pressure suppression pool 5. In the reactor pressure vessel 1, a recirculation system consisting of a recirculation pump 31 and piping 32 for forcibly circulating the reactor core flow rate is provided in the reactor containment vessel 2. A mechanical seal portion of the recirculation pump 31 is provided with a pipe 33 that communicates with the waste treatment device 28 .

Further, a fuel storage pool 38 and a skimmer surge tank 39 connected thereto are provided in the upper part of the reactor building 6 (comprised of a purification system pump 40, a heat exchanger 41, and a purification system 42). ) and a pipe 43 connecting the reactor well 4a constitute a fuel storage pool cooling and purification system.

The pressure suppression pool 5 includes an emergency cooling pump 34,
The reactor pressure vessel 1 and the piping 36 via the valve 35
are connected to form the emergency core cooling system.
Also, outside the pressure suppression pool 5 are a purification system (consisting of a pump 45, a heat exchanger 46, and a purification device 47), piping 48 connecting these, and piping bypassing the heat exchanger 46 and purification device 47. 49
A pressure suppression pool cooling and purification system will be installed. The downstream side of the purification device 47 in this system is connected to the waste treatment device 28 by a pipe 52 via a valve 51. The pressure suppression pool 5 is provided with a water level sensing device 50 whose signal is interlocked for use as an input to the valve 51 and pump 53. Further, the suction side of the pump 40 of the fuel pool cooling and purification system and the pressure suppression pool 5 are connected to the piping 4.
4a, and is connected to the downstream side of the purifier 14 of the water supply system by a pipe 21a. The pressure suppression pool 5 and the main condenser 8 are connected to a piping 23 via a make-up water pump 22.
Connected by a.

FIG. 3 is a system diagram showing details of the pressure suppression pool cooling and purification system shown in FIG. 2, and the same parts as in FIG. 2 are given the same reference numerals.

A pump 45 is provided outside the pressure suppression pool 5 and is connected to the pressure suppression pool 5 via a valve 55 through a pipe 48, which is connected to a heat exchanger 46, a purification device 47, a flow rate detection device 56, and a valve 57. 58,5
9 are connected to each other to form a closed loop returning to the pressure suppression pool 5. Piping 9 and valves 60a, 60 that bypass the heat exchanger 46 and purifier 47
b, 60c are provided. The valves 55 and 59 are automatically driven and have the function of isolation valves. or,
Figures 4 and 5 show details of the suction section in the pressure suppression pool 5 of this system, and the same parts as in Figures 1 to 3 are given the same reference numerals for explanation. do.

In the example of a Mark I type boiling water nuclear power plant, the pressure suppression pool 5 has a donut shape with a circular cross section as shown in Figs. 4 and 5, and is composed of a plurality of segments. A reinforcing ring 5a is provided between each segment. Since these reinforcing rings 5a are attached in the form of protrusions within the pressure suppression pool 5, the contaminants that accumulate at the bottom of the pressure suppression pool 5 will accumulate in each segment and are not expected to migrate between segments. Therefore, a suction sparge is provided for each segment. The suction spargeer has 48 small holes.
A pipe 48 located at the center of the bottom with a
b, a header 48d installed at a higher place and closer to the wall, and connected via a valve 48c.
It is assumed that the suction section is configured as follows. The header 48d is connected to the pipe 48, but the header 48d may be a plurality of pieces or a single piece.
It goes without saying that the valve 48c is a remotely controllable valve. Furthermore, in a pressure suppression pool with a flat bottom, the spargeers may be provided at certain intervals.

The action will be explained below. Steam generated within the reactor pressure vessel 1 is sent to the turbine 7 through the main steam pipe 9, rotates the turbine 7, and is condensed in the main condenser 8. In some cases, the water passes through a pipe 11 that bypasses the turbine and is condensed in the main condenser 8.
The water condensed in this way is pressurized by the condensate pump 13 and purified by the purifier 14, and then a part of the water is sent to the pipe 21a.
The remaining water is heated by feed water heaters 15 and 17, pressurized by booster pump 16a and feed water pump 16b, and returned to reactor pressure vessel 1 through water supply pipe 19.

The control rod drive device 26 provided at the bottom of the reactor pressure vessel 1 is connected to the pressure suppression pool 5 during normal reactor operation.
Cooled by water. This water flows into the reactor pressure vessel 1 through the control rod drive device 26 . Note that the control rod drive device 26 may be cooled by taking water from the downstream side of the purification device 14 of the condensate water supply system.
Also, during a reactor scram, the control rod drive device 2
The waste water from 6 is sent to the waste treatment device 28 via piping 27b. In addition, the staging flow rate from the mechanical seal part of the recirculation pump 31 that forcibly circulates the cooling material inside the reactor is also sent to the waste treatment device 28, but this water is purified by this device and sent for reuse. The water is returned to the pressure suppression pool 5 by the pump 53, and the remaining water is discharged into the pit 29 and taken out of the plant.

In the fuel storage pool cooling and purification system, the pressure is increased by a pump 40 and returned to the fuel storage pool 38 through a heat exchanger 41 and a purification device 42 to remove decay heat from the spent fuel and purify the pool water.

At the time of fuel exchange, the reactor well 4a is filled with water, and at that time, water from the pressure suppression pool 5 is injected into the reactor pressure vessel 1, and water is poured into the reactor well 4a from the upper part of the reactor pressure vessel 1 with the top cover removed. The water is drained out and filled with water. Further, when draining water from the reactor well 4a, the valve of the pipe communicating with the reactor well of the fuel storage pool cooling and purification system is opened, and water is drained into the pressure suppression pool 5 through the pipe 44a or the pipe 68. In either case, the reactor is shut down and the reactor core is filled with water, so there is no safety problem.

The water level of the pressure suppression pool 5 is set based on the minimum water level based on the steam condensation capacity in the event of a loss of coolant accident, and based on the restriction of the air volume (space) within the pressure suppression pool 5, which is related to the design internal pressure of the pressure suppression pool 5 as a containment device. It is necessary to determine the highest water level respectively. A water level detection device 50 is provided for this purpose, and when the water level exceeds the maximum water level, a valve 51 is opened to send the water to the waste treatment device 28 or drain it to the pit 29. If the water level falls below the minimum water level, condensate is supplied from the waste treatment device 28 to the pressure suppression pool 5 using the pump 53. Alternatively, it is of course possible to replenish water from a replenishment water tank as in the conventional case. Therefore, although the water level detection device 50, pump 53, and valve 51 are interlocked, the reactor is stopped at the time of fuel change, so there is no need for water level control and the interlock can be removed.

Water in the pressure suppression pool 5 is pressurized by a pump 45, cooled and purified through a heat exchanger 46 and a purification device 47, and returned to the pressure suppression pool 5 for management of pool water. The faster the suction speed from the spargeers, the better the material around them will be sucked in, and this can be done by appropriately opening and closing the valves 48c provided on each spargeer. Therefore, the pump may have a low capacity. Heat exchanger 46, purification device 4
7 may be bypassed when it is not necessary. Also, the flow rate of this system is adjusted by the flow rate detection device 5.
6 and a throttle valve 57. or,
Valves 55 and 59, as well as other isolation valves, shall be interlocked so that they will automatically close in the event of an accident requiring isolation of the pressure suppression pool. It goes without saying that the devices in this system do not have to be arranged in the order described above. The quality of the water in the pressure suppression pool 5 can be sampled, investigated, and checked using an existing sampling device.

As explained above, the pressure suppression pool 5 water can be cooled and purified by the pressure suppression pool cooling and purification system, so the pool water becomes condensate with low radioactivity, reducing the dose rate in the pressure suppression pool 5 and its surroundings. This will result in lowering the value. Therefore, when repairing equipment and piping, etc., the exposure to radiation for workers is reduced, which in turn shortens the repair period and contributes to improving the operating rate of the nuclear power plant. or,
The volume of water in the pressure suppression pool is approximately the same as the volume of water stored in the condensate storage tank (approximately 2000m ³ ), and by keeping the pressure suppression pool water clean at all times, it combines the functions of a condensate storage tank with a pressure suppression pool. This makes it possible to eliminate the condensate storage tank, which not only improves the economic efficiency of the equipment, but also reduces pressure suppression pools, including the reactor containment vessel, compared to condensate storage tanks that are open to the atmosphere. Since it is a closed container that is isolated from the atmosphere, the amount of dissolved gases harmful to piping, such as dissolved oxygen, is reduced.
Furthermore, even if the pressure suppression pool water is injected into the reactor pressure vessel by the emergency core cooling system or the like, the quality of the pool water is controlled, so there is almost no effect on the reactor internals. In addition, it can not only purify pool water, but also cool it, and lower the pool water temperature to the lowest possible temperature.
Because it is almost no longer subject to such restrictions,
The safety of nuclear reactors can be further improved.

Furthermore, in this embodiment, the condensate storage tank 20
However, the condensate storage tank is not removed and is installed in the same way as before, and the pressure suppression pool is combined with the function of a condensate storage tank. Of course, both the suppression pool and the suppression pool may be provided, and in this case, in addition to the above advantages, there will be a plurality of clean water sources, and the safety of the reactor will be further improved.

It goes without saying that the pressure suppression pool may have a condensate storage tank with conventional functions and a pressure suppression pool water cooling and purification system.

Fig. 6 is a system diagram showing another embodiment of the pressure suppression pool water cooling and purification system in the nuclear power plant according to the present invention, and the same parts as in Fig. 2 are given the same reference numerals for explanation. shall be.

There is a fuel storage pool 3 in the upper part of the reactor building 6.
8 and the skimmer surge tank 39 connected to this
A fuel storage pool cooling and purification system is constituted by a pump 40, a heat exchanger 41, a purification device 42, and piping 43 and valves connecting these to the reactor well 4a. Further, a pipe 44b and valves 61, 63 connecting the pressure suppression pool 5, an auxiliary pump 62 located outside the pool, and the suction side pipe of the pump 40 of the fuel storage pool cooling and purification system, and a pump of the fuel storage pool cooling and purification system. 40, a heat exchanger 41, a purification device 42, and a pipe 43 connecting them are shared, and the downstream side of the purification device 42,
A system consisting of a pipe 68 and valves 65, 66, and 67 connecting the pressure suppression pool 5 is provided. In other words, it is a pressure suppression pool cooling and purifying system that shares the pump 40, heat exchanger 41, and purifier 42 of the fuel storage pool cooling and purifying system. However, it goes without saying that the arrangement order of the pump 40, heat exchanger 41, and purifier 42 does not necessarily have to be as shown in the figure. Note that the auxiliary pump 62 may not always be necessary due to the arrangement of the equipment.

In the fuel storage pool cooling and purification system, water overflowing from the fuel storage pool 38 flows through a weir into a skimmer surge tank 39, is pressurized by a pump 40, is cooled and purified by a heat exchanger 41 and a purification device 42, and is reused as fuel. Returned to storage pool 38. On the other hand, the pressure suppression pool cooling purification system cools the pressure suppression pool 5 water,
The pressure is increased by an auxiliary pump 62 in order to flow into the suction side of the pump 40 of the fuel storage pool cooling and purification system located several tens of meters above the ground. The pool water is pressurized by the pump 40 and cooled and purified through the heat exchanger 41 and the purifier 42, and is returned to the pressure suppression pool 5 via the piping 68.

Reactor water flows into the pressure suppression pool 5 when the turbine exhaust for driving the pumps of the emergency core cooling system, when the main steam relief safety valve is activated, and when the reactor shutdown cooling system is started or stopped. If the pressure suppression pool 5 water is purified, the pool water will not be contaminated so much unless the above-mentioned devices are operated. On the other hand,
Immediately after a fuel change, the fuel storage pool cooling and purification system requires continuous operation to remove heat and purify the fuel storage pool, but in this case as well, once the fuel storage pool water is purified, it will not become contaminated. There is no need for continuous operation if the decay heat of the fuel removed from the core and stored falls. Therefore, by combining both systems and sharing some equipment, it is possible to rationalize the systems without impairing the functions of both systems. In this way, similarly to the embodiment shown in FIG. 2, the pressure suppression pool water can be cooled and purified.
This reduces the dose rate in the pressure suppression pool and its surroundings, reduces exposure to workers, contributes to shortening construction periods, and improves the operating rate of nuclear power plants.
Furthermore, the condensate storage tank can be removed, improving economic efficiency, and since the pressure suppression pool is a closed container, water with low dissolved gases can be obtained, greatly reducing the impact on equipment, piping, etc. Furthermore, even if the pressure suppression pool water is injected into the reactor, there is almost no effect on the reactor internal structures. Furthermore, since it is also possible to cool the pressure suppression pool water, the safety of the entire reactor is of course improved.

Also, in this embodiment, the function of the condensate storage tank may be combined with the pressure suppression pool, and the condensate storage tank may be deleted, or both the condensate storage tank and the pressure suppression pool may be provided, and either one may be used as a backup. Of course, it can also be used as a water source.

[Brief explanation of the drawing]

Fig. 1 is a schematic system diagram showing the flow of water around a conventional boiling water nuclear power plant, Fig. 2 is a schematic system diagram showing an embodiment of the nuclear power plant according to the present invention, and Fig. 3 is Fig. FIG. 4 is a system diagram showing an embodiment of the pressure suppression pool cooling and purification system of FIG. 3, and FIG. FIG. 6 is a perspective view showing the details of the suction sparge part by cutting out a part of the pressure suppression pool, and FIG. 6 is a system diagram showing another embodiment of the pressure suppression pool cooling and purification system. 5... Pressure suppression pool, 8... Main condenser, 20
... Condensate storage tank, 22 ... Make-up water pump, 2
4... Control rod drive pump, 25... Water pressure control unit, 26... Control rod drive device, 28... Waste treatment device, 31... Recirculation pump, 34... Emergency core cooling pump, 38... Fuel storage pool, 3
9... Skimmer surge tank, 40... Pump,
41... Heat exchanger, 42... Purification device, 45...
Pump, 46... heat exchanger, 47... purification device,
48, 49...Piping, 48a...Small hole, 48b...
...Suction spargeer, 48c...Valve, 48d...Header, 50...Water level detection device, 56...Flow rate detection device, 62...Pump.

Claims (1)

[Claims] 1. A reactor pressure vessel, a reactor well provided in the vicinity of the reactor pressure vessel, a first pipe led out from the reactor well, and a connection to the first pipe. A purifier system comprising a first pump, a heat exchanger, and a purifier, a second pipe provided downstream of this purifier system, and this second pipe are connected. a fuel storage pool, a skimmer surge tank connected to the fuel storage pool and connected to the first pipe, a pressure suppression pool from which water from the purification system is led out, and water in the pressure suppression pool. A nuclear power plant, comprising: a third pipe that introduces water into a purification system; and a second pump provided in the third pipe. 2 The purifier system includes a first pump from the upstream side,
The nuclear power plant according to claim 1, characterized in that a heat exchanger and a purification device are connected in this order. 3 The purifier system includes a first pump from the upstream side,
The nuclear power plant according to claim 1, characterized in that a purification device and a heat exchanger are connected in this order. 4. A patent claim characterized in that the water in the pressure suppression pool is introduced directly upstream of the purification device through the third pipe, and is led out from the immediately downstream side of the purification device and introduced into the pressure suppression pool. A nuclear power plant according to item 2 or 3 within the scope of .