JPH0550714B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a nuclear reactor in which coolant within a reactor pressure vessel is circulated by an internal pump, and particularly to a drive device for the internal pump.

[Technical background of the invention]

Generally, in a boiling water reactor, the flow rate of coolant in the reactor is adjusted as one means for controlling the output of the reactor. In order to operate a nuclear reactor at its rated capacity, it is necessary to force a flow rate greater than that obtained by natural convection of the coolant, and for this purpose a reactor coolant recirculation system is installed.

There are two types of configurations for this reactor coolant recirculation system, one of which is to take the coolant out of the reactor pressure vessel, pressurize the extracted coolant with a pump, and return it to the reactor pressure vessel. By returning it to the inside, a circulating flow is generated within the pressure vessel. Another method is to incorporate the pump impeller inside the reactor pressure vessel, eliminating the need for piping outside the pressure vessel. The pumps used in this latter configuration are called internal pumps, and in a standard-sized nuclear reactor with an electrical output of 1.3 million kW, 12 internal pumps are built into the reactor pressure vessel. There is.

A conventional configuration of a nuclear reactor equipped with this internal pump is shown in FIG.

In FIG. 1, a cylindrical core shroud 2 is disposed inside a reactor pressure vessel 1, and a reactor core 3 is formed inside this core shroud 2. As shown in FIG. The coolant filled in the reactor pressure vessel 1 is heated in the reactor core 3 to become a mixture of steam and water, and this mixture is separated at the upper part of the reactor pressure vessel 1. (not shown) and used for power generation. On the other hand, after rotating the turbine, the separated water descends in the reactor pressure vessel 1 outside the core shroud 2 together with the water condensed by the condenser, bypasses the lower end of the core shroud 2, and returns to the reactor pressure vessel 1. It is supplied to the reactor core 3. The circulating flow rate of the coolant within the reactor pressure vessel 1 is regulated by twelve internal pumps 4 connected in the circumferential direction at the bottom of the reactor pressure vessel 1. This internal pump 4 is configured to rotate an impeller 7 facing into the reactor pressure vessel 1 via a rotating shaft 6 by driving a motor 5 provided inside.

In addition to the internal pump 4, a reactor coolant purification system for circulating coolant is also provided. This reactor coolant purification system includes a first suction pipe 8 connected to the reactor pressure vessel 1 at a position higher than the reactor core 3, and a second suction pipe 9 connected to the lowest part of the reactor pressure vessel 1. These suction pipes 8 and 9 are connected to a main pipe 10. Two circulation pumps 11, 11 are installed in parallel in this main line 10 to circulate the coolant, and the downstream end of the main line 10 is connected to the reactor pressure vessel 1. Also,
A heat exchanger inlet valve 12 and an outlet valve 13, each of which is normally open, are installed in series in the main pipe line 10, and the outlet valve 1 is connected from the downstream side of the inlet valve 12 to the outlet valve 1.
A regenerative heat exchanger 14, a non-regenerative heat exchanger 15, and a filtration desalination device 16 are interposed in this order upstream of the heat exchanger 3. Among these, the regenerative heat exchanger 14 also faces the downstream pipe line 10b of the filtration and demineralization device 16, and gives the heat taken from the coolant to the coolant downstream of the filtration and demineralization device 16 to be cooled once. The system is designed to heat the coolant again. Further, the non-regenerative heat exchanger 15 is provided with a cooling water pipe line 17, so that the cooling water is cooled by external cooling water. Furthermore, the main pipe 10a on the upstream side of the inlet valve 12 and the main pipe 10c on the downstream side of the outlet valve 13 are connected by a bypass pipe 19 having a normally closed bypass valve 18 interposed therein.

According to the configuration described above, the circulation pumps 11, 11
is driven by the main pipe 1 through both suction pipes 8 and 9.
The coolant in the reactor pressure vessel 1 supplied to
It passes through a regenerative heat exchanger 14 and a non-regenerative heat exchanger 15 to be cooled, and then passes through a filtration and demineralization device 16 to remove impurities. Then, it is heated by the regenerative heat exchanger 14 and then returned to the reactor pressure vessel 1.

FIG. 2 shows a state in which the conventional internal pump 4 and reactor coolant purification system described above are normally powered off. Since the internal pumps 4 are supplied with power from the normal power source, they all stop, and therefore the circulating flow inside the reactor pressure vessel 1 becomes very weak.If left in this state, the reactor Coolant with a relatively low temperature and high specific gravity accumulates in the lower part of the reactor pressure vessel 1, and only the lower part of the reactor pressure vessel 1 gradually cools down.
However, in order to prevent abnormal thermal stress from acting on the reactor pressure vessel 1, the temperature difference between the upper and lower parts of the reactor pressure vessel 1 must be kept within 80°C, so The circulation pumps 11, 11, which can be driven by the current of This prevents low-temperature coolant from accumulating at the bottom. At this time, the inside of the reactor pressure vessel 1 is kept at the rated temperature to make it easier to restart the reactor.
When the pressure is to be maintained, the inlet valve 12 and outlet valve 1 of the main line 10 are closed, as shown in FIG.
3 is closed, the bypass valve 18 of the bypass pipe 19 is opened, and the coolant is circulated through the bypass pipe 19 without passing the coolant through the heat exchangers 14, 15, etc., which is a so-called high temperature standby operation. I'm starting to do it.

[Problems with background technology]

In such a conventional system, the internal pump 4 normally stops when the power is cut off, so the high-temperature standby operation of the reactor must be performed by the reactor coolant purification system. The reactor coolant purification system requires a bypass pipe line 19, which makes the configuration of the reactor coolant purification system complicated.

[Object of the Invention] In view of these points, an object of the present invention is to provide an internal pump drive device that can simplify the configuration of a nuclear reactor coolant purification system.

[Summary of the invention]

In the present invention, four internal pumps separated from each other at an angle of 90 degrees are connected to an emergency diesel generator that supplies power to each of the four emergency core cooling systems, and one emergency One internal pump can be driven by current from a diesel generator, and the internal pump circulates coolant within the reactor pressure vessel without using the reactor coolant purification system. It is.

[Embodiments of the invention]

The present invention will be explained below with reference to embodiments shown in the drawings. Note that the same components as those of the conventional device described above are denoted by the same reference numerals in the drawings, and the explanation thereof will be omitted.

FIG. 3 shows an embodiment of the present invention, in which twelve internal pumps 4, 4... are arranged at equal intervals in the circumferential direction at the lower end of the reactor pressure vessel 1. All internal pumps 4 are supplied with power from a normal power supply bus 20. Furthermore, four of these internal pumps 4A
is also connected to the emergency diesel generator 21, and is also driven by the current from the emergency diesel generator 21. Since the emergency core cooling system is divided into four systems, there are also four emergency diesel generators 21, and one emergency diesel generator 21 supplies power to one internal pump 4A.

Next, the operation of the embodiment described above will be explained.

Normally, when the power is cut off, each internal pump 4
loses its normal power source, and the internal pump 4, which is not connected to the emergency diesel generator 21, continues to stop. On the other hand, the internal pump 4A connected to the emergency diesel generator 21 automatically restarts after the emergency diesel generator 21 automatically starts after the normal power is cut off, and the internal pump 4A connects to the reactor pressure vessel. The coolant inside 1 is circulated.

In order to prevent relatively low-temperature coolant from accumulating at the bottom of the reactor pressure vessel 1, a flow rate of about 25% or more of the coolant rated flow rate is required. It is only necessary to drive three or more internal pumps 4A out of a certain internal pump 4. Therefore, in this embodiment in which four internal pumps 4A are driven by the emergency diesel generator 21, this fully satisfy the conditions. Furthermore, since the four internal pumps 4A driven by the emergency diesel generator 21 are separated from each other at an angle of 90 degrees, a uniform circulating flow of coolant is formed within the reactor pressure vessel 1. Ru.

In the above embodiment, it was explained that when the emergency diesel generator 21 is automatically started, the internal pump 4A connected to the emergency diesel generator 21 section is automatically restarted. , the internal pump 4A may be restarted by remote manual operation by a worker. That is, the emergency diesel generator 21
supplies power to devices other than the internal pump 4A, but since the electrical load is at its maximum during startup before reaching rated operation, if all devices are started automatically at any time, the capacity of the emergency diesel generator 21 will be reduced. There is a risk that the emergency diesel generator 21 will be overloaded. Therefore, increasing the capacity of the emergency diesel generator 21 eliminates the risk of overload, but if the emergency diesel generator 21 is started at a different start time from other equipment by remote manual operation by a worker, Emergency diesel generator 2
The risk of overload is eliminated without increasing the capacity of 1.

As mentioned above, some internal pumps4
In a configuration in which A is connected to the emergency diesel generator 21, reactor coolant as shown in FIG. It can be configured as a purification system. That is, the internal pump 4A is powered by the emergency diesel generator 21 after the normal power supply is cut off.
By driving the reactor pressure vessel 1, it is possible to prevent relatively low temperature coolant from accumulating in the lower part of the reactor pressure vessel 1.
The reactor coolant purification system does not need to perform high-temperature standby operation, and therefore the reactor pressure vessel 1
It is sufficient to extract the coolant from a position higher than the upper end of the reactor core 3 using only the suction pipe 8.

As a result, the second suction pipe 9 in FIG. 1 can be omitted, reducing the possibility of an accident in which coolant leaks and is lost from a portion of the reactor pressure vessel 1 lower than the reactor core 3, thereby increasing the reliability of the reactor. You can increase your sexuality.

In addition, the bypass pipe line 19 of the reactor coolant purification system
Since the inlet valve 12 and the outlet valve 13 can also be omitted, the system and operating method can be simplified.

Furthermore, by omitting both conduits 9 and 19, it is also possible to reduce the radiation exposure of workers during periodic inspections.

〔Effect of the invention〕

As explained above, the internal pump drive device of the present invention operates four internal pumps separated by an angle of 90 degrees from each other, and supplies power to each of the four emergency core cooling systems. The system is connected to an emergency diesel generator, and one internal pump can be driven by the current from one emergency diesel generator, so even if the normal power is cut off, coolant can be supplied only within the reactor pressure vessel. The reactor coolant purification system can be easily configured, and four internal pumps separated at 90° from each other are driven by an emergency diesel generator. Therefore, even in an emergency, the flow of coolant inside the reactor pressure vessel can be made uniform, and the conventional emergency diesel generator can be used, eliminating the need to add a new generator. Emergency diesel generators can be used efficiently, and each of the four emergency diesel generators drives one internal pump, greatly increasing the capacity of the emergency diesel generators. It produces an effect that is not necessary.

[Brief explanation of the drawing]

Figure 1 is a pipeline diagram showing a reactor coolant purification system using a conventional internal pump drive device, and Figure 2 is a pipeline diagram showing the high-speed standby operation state of the reactor coolant purification system in Figure 1. 3 is a schematic plan view showing an embodiment of the internal pump drive device according to the present invention, and FIG. 4 shows a reactor coolant purification system to which the internal pump drive device of FIG. 3 is applied. It is a pipe diagram. 1...Reactor pressure vessel, 3...Reactor core, 4,4A...Internal pump, 8,9...Suction pipe, 14,1
5... Heat exchanger, 16... Filtration desalination device, 19... Bypass pipeline, 20... Normal power supply bus, 21... Emergency diesel generator.

Claims (1)

[Claims] 1. In a nuclear reactor in which cooling water in a reactor pressure vessel is circulated by a plurality of internal pumps, four internal pumps separated by an angle of 90 degrees from each other are It is characterized by being connected to an emergency diesel generator that supplies power to each of the four emergency core cooling systems, so that one internal pump can be driven by the current from one emergency diesel generator. Drive system for internal pumps in nuclear reactors. 2. The internal pump connected to the emergency diesel generator is configured to be automatically restarted by the current from the emergency diesel generator when the normal power supply is lost. Internal pump drive device. 3. The internal pump connected to the emergency diesel generator is restarted by current from the emergency generator after manual operation when the power is lost. The internal pump drive device according to item 1.