JPS61173196A - Remaining heat removing device for boiling water type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is capable of selectively performing decay heat removal operation, etc. during reactor shutdown, and extraction and condensation operation of excess steam from the main steam pipe during reactor operation. This invention relates to residual heat removal equipment for boiling water reactors.

[Technical background of the invention]

In boiling water reactors, decay heat of radioactive materials is generated in the core of the reactor pressure vessel even when the reactor is shut down.
In order to prevent overheating caused by this, a residual heat removal device is provided that cools the reactor by circulating the reactor water outside.

FIG. 4 shows a conventional example of such a residual heat removal device for a boiling water reactor.

Piping 2 for reactor water circulation is led out from the reactor pressure vessel 1,
A reactor water circulation pump 3 circulates reactor water to a heat exchanger 'a4 connected to the piping 2. heat exchanger 4
is of the heat exchanger tube type, and a large number of U-shaped heat exchanger tubes 6 are provided within the cylinder 5. Piping 2 is connected to the internal space of the circle Ji5 of this heat exchanger 4, and this space is used as a flow path for reactor water. Cooling water piping 8 of an m-unit cooling heat exchanger 7 for cooling reactor m-units is connected to the heat transfer tube 6, and equipment cooling water is circulated within the heat transfer tube 6 by an equipment cooling water pump 9. The reactor water flowing on the outer surface of the heat tube 6 is cooled. In the device cooling heat exchanger 7, the device cooling water is cooled by exchanging heat with sea water or the like 10.

By the way, the main steam pipe 11 led out from the reactor pressure vessel 1
is provided with a pressure regulating valve 12, and for example, when the turbine load decreases, surplus steam is transferred to the pressure regulating valve 12.
It is designed to be discharged from The heat exchanger 4 is used to condense this excess steam and lead it to the pressure suppression boule 13. That is, the pressure regulating valve 1 is installed in the main steam pipe 11.
A heat exchanger 4 is connected through the reactor 2, and during reactor operation, the valve 14 of the reactor water circulation pipe 2 is opened to introduce excess steam to the heat exchanger 4 instead of reactor water. When condensing excess steam, the valve 16 of the condensed water discharge pipe 15 connecting the heat exchanger 4 and the pressure suppression boule 13 is opened, and the condensed water 19 is opened.
is discharged into the pressure suppression boule 13.

In the conventional residual heat removal device, the heat exchanger 4 is of a vertical type, and the inlet 17 for the reactor water or surplus steam of the heat exchanger 4 is provided in the upper part of the cylinder 5, so that the reactor water and surplus steam condensed water can be An outlet 18 is provided at the bottom of the cylinder 5. When condensing excess steam, the condensed water discharge pipe 15
By opening the valve 16 and adjusting the water level of the condensed water 19 stored in the cylinder 5, the contact area of the surplus steam with the heat transfer tube 6 is adjusted, thereby controlling the amount of condensation of the surplus steam. ing.

In addition, the steam generated from the core of the reactor pressure vessel 1 includes
Contains non-condensable gases. This non-condensable gas is
Due to the condensation action of surplus steam, it accumulates inside the cylinder 5 of the heat exchanger 4, and if the accumulation port becomes too large, the steam condensing performance of the surface of the heat exchanger tube 6 will be reduced. For this reason,
A non-condensable gas discharge pipe 20 is provided in the middle of the cylinder 5 to discharge the accumulated non-condensable gas to the outside.

[Problems with background technology]

As mentioned above, in the conventional residual heat removal device, since it is necessary to have a structure that can discharge non-condensable gas from the heat exchanger 4, reactor water or surplus steam is made to flow inside the cylinder 5,
On the other hand, equipment cooling water is made to flow inside the heat exchanger tubes 6.

Therefore, in such a configuration, the pressure of the reactor water or surplus steam flowing outside the heat exchanger tubes 6 is higher than that of the equipment cooling water flowing inside the heat exchanger tubes 6, so the heat exchanger tubes 6 must be designed with external pressure. Therefore, the wall thickness of the heat exchanger tube 6 increases.

As a result, the heat transfer performance of the heat transfer tubes 6 is lowered, resulting in problems such as an increase in the heat transfer area and the size and weight of the heat exchanger itself.

In addition, since the latent heat of steam is extremely large, the exchange heat exchanger required for condensing surplus steam is extremely large. Conventionally, all of the condensing action of such surplus steam is performed by equipment cooling water flowing through the heat exchanger 4. Therefore, the configuration of the equipment cooling heat exchanger 7 also had to be enlarged.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a residual heat removal device for a boiling water reactor that can reduce the size and weight of a heat exchanger without inhibiting the discharge of non-condensable gases. The purpose is to

[Summary of the Invention] In order to achieve the above object, the present invention connects a heat exchanger type heat exchanger to the reactor water circulation piping led out from the reactor pressure vessel, and also installs a pressure control valve in the main steam pipe. The heat exchanger is connected through the boiling water reactor, thereby making it possible to selectively perform reactor water residual heat removal operation during reactor shutdown and excess steam condensation operation during reactor operation. In the apparatus, a piping for circulating reactor water and an excess steam introduction pipe from the main steam pipe are connected to the water chamber on the inlet side of the heat exchanger tube of the heat exchanger, and the inside of the heat exchanger tube is used as a flow path for reactor water and surplus steam. In addition, the water chamber on the outlet side of the heat transfer tube is connected to the pressure suppression pool through a condensed water discharge pipe and a steam discharge pipe.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

A reactor water circulation pipe 22 is led out from the reactor pressure vessel 21, and a reactor water circulation pump 23 circulates the reactor water. A heat exchanger 24 is connected to this pipe 22.

This heat exchanger 24 has a horizontal heat exchanger tube type configuration, and the axis is a horizontal circle II! A large number of U-shaped heat exchanger tubes 26 are provided within the tube 25. At both ends of the U-shaped heat exchanger tube 26, the inside of the cylinder 25 is divided into upper and lower parts, and an inlet side water chamber 27 and an outlet side water chamber 28 are provided.
is formed. Piping 22 for circulating reactor water communicates with an inlet side water chamber 27 and an outlet side water chamber 28 of heat transfer tubes 26 of this heat exchanger 24 . Note that the piping 22 is equipped with a valve 2 for opening and closing the flow path.
There are 9.

Further, a pressure regulating valve 30 of a main steam pipe 31a led out from the reactor pressure vessel 21 is connected to the inlet side water chamber 27 of the heat transfer tube 26 via a surplus steam introduction pipe 31. Furthermore, the lower part of the water chamber 28 on the outlet side of the heat transfer tube 26 is connected to a pressure suppression pool 32.
It is connected to via a condensed water discharge pipe 33. In addition, the upper part of the outlet side water chamber 28 is connected to the pool water 34 of the pressure suppression pool 32.
It is connected to the inside via a steam exhaust pipe 35. Note that the condensed water discharge pipe 33 and the steam discharge pipe 35 are provided with valves 36 and 37 for flow control, respectively. In addition, the steam exhaust pipe 3
A so-called quencher 38, which is a metal fitting having a fine air discharge hole, is attached to the tip of the tube 5.

On the other hand, the cooling water piping 40 of the equipment cooling heat exchanger 39 is connected to the internal space of the cylinder 25 of the heat exchanger 24, and the equipment cooling water pump 41 circulates the III-cooling water into the cylinder 25. ing. The device cooling heat exchanger 39 exchanges heat between the device cooling water and seawater or the like 42 .

Next, the effect will be explained. When removing residual heat due to decay heat etc. during reactor shutdown, valve 29 of piping 22 for reactor water circulation
, and the reactor water circulation pump 23 is driven. Also, the equipment cooling water pump 41 of the equipment cooling heat exchanger 39 is driven, and the cooling I
Equipment cooling water is made to flow through the J1 water pipe 40. In this case, the valves 36 of the condensed water discharge pipe 33 and the steam discharge pipe 35
．． 37 is closed. As a result, in the heat exchanger 24 for residual heat removal, the reactor water flowing through the heat transfer tubes 26 is cooled by exchanging heat with the equipment cooling water flowing inside the cylinder 25, and the reactor water that has become low temperature is The residual heat is circulated into the furnace pressure vessel 21 to remove residual heat.

In addition, when surplus steam generated during reactor operation is to be condensed, the valve 29 of the reactor water circulation pipe 22 is closed, and the valves 36 of the condensed water discharge pipe 33 and the steam discharge pipe 35 are closed.
Open 37. Then, surplus steam in the main steam pipe 31a flows from the surplus steam introduction pipe 31 into the inlet side water chamber 27 via the pressure control valve 30, and then passes through the heat transfer pipe 26 and is condensed by heat exchange with equipment cooling water. It is discharged into the water chamber 28. Note that a part of the surplus steam passing through the heat exchanger tube 26 is not condensed and is discharged from the heat exchanger tube 26 to the outlet side water chamber 28 together with the condensed water as steam. The steam and condensed water are separated in the outlet water chamber 28, and the condensed water accumulated in the lower part of the outlet water chamber 28 is discharged to the pressure suppression pool 32 via the condensed water discharge pipe 35. On the other hand, the steam discharged to the upper part of the outlet side water chamber 28 is discharged into the pool water 34 of the pressure suppression pool 32 through the steam discharge pipe 35 and condensed.

The steam released from the steam exhaust pipe 35 into the pool water 34 becomes minute bubbles via the quencher 38, so it causes vibrations! There will be no impact.

Note that when condensing excess steam, non-condensable gas contained in the steam needs to be discharged from the heat exchanger 25.

Therefore, instead of condensing all of the steam within the heat transfer tube 26, a portion of the steam is guided to the outlet side water chamber 28 in a steam state as described above. Such a heat exchanger tube 26
In order to control the steam flow rate in the steam exhaust pipe 35, the flow rate control valve 37 of the steam exhaust pipe 35 is adjusted. In other words, if the opening degree of the steam flow rate control valve 37 is increased to increase the volume of discharged steam, the amount of steam discharged from the outlet side water chamber 28 will increase. The outflow of gas is promoted, and the concentration of non-condensable gas remaining in the heat exchanger tubes 26 is also reduced.

This improves the contact between the inner surface of the heat transfer tube 26 and the steam passing therethrough, and increases the amount of steam condensed.

According to such a configuration, in the heat exchanger 24 for residual heat removal, reactor water or surplus steam having a higher pressure than the equipment cooling water is made to flow inside the heat transfer tube 26, so that the heat transfer tube 26 has an internal pressure. design, and the wall thickness of the heat transfer tube 26 can be reduced. Therefore, the heat transfer performance of the heat transfer tube 26 is improved,
Not only can the heat transfer area be reduced, but the heat exchanger itself can also be made smaller and lighter.

In addition, since a part of the steam is guided from the upper part of the water chamber 28 on the outlet side of the heat transfer tube 26 to the pressure suppression pool 32 via the steam exhaust pipe 35, when excess steam is condensed during reactor operation, the steam is The non-condensable gas contained therein does not accumulate in the heat exchanger tubes 26, and therefore good contact between the inner surface of the heat exchanger tubes 26 and the steam is maintained.

Furthermore, since a part of the steam is discharged and condensed into the pool water 34 of the pressure suppression & 11 boule 32, the amount of heat exchanged in the heat exchanger 24 is reduced by the amount of heat exchanged in the pool water 34. It turns out. Therefore, equipment cooling heat exchanger 3
The configuration of 9 itself can also be downsized.

In addition, according to the configuration of the embodiment in which the heat exchanger 24 is of a horizontal type, maintenance, inspection, etc. can be performed more easily than in the case of a conventional vertical type.

In addition, in the above embodiment, the condensed water discharge pipe 33 and the steam discharge pipe 35 were directly led to the pressure suppression 1111 pool 32.
The present invention is not limited to such a configuration; for example, as shown in FIG. 3, a tank 43 for water level control may be provided in the middle of the condensed water discharge pipe 33.

With this configuration, by adjusting the valve 37 of the condensed water discharge pipe 33 and controlling the water level inside the outlet side water chamber 28 communicating with the tank 43, a part of the heat transfer tube 26 can be condensed. By submerging in water, the amount of steam condensation can be controlled to various values. Therefore, the amount of steam condensation can be accurately and easily controlled.

In addition, in FIG. 3, the tank 43 has a structure in which it communicates with both the condensed water discharge pipe 33 and the steam discharge pipe 35, but it goes without saying that the tank 43 may have a structure in which it communicates only with the condensed water discharge pipe 33. It is.

〔Effect of the invention〕

As described above, according to the residual heat removal device for a boiling water reactor according to the present invention, the heat exchanger tube of the heat exchanger for residual heat removal is used as a flow path for reactor water and surplus steam, and high-pressure reactor water or surplus steam is Since the heat exchanger is made to flow through the inside of the heat exchanger tube, it is possible to reduce the wall thickness of the heat exchanger tube, thereby improving heat transfer performance and making it possible to make the heat exchanger itself smaller and lighter.

In addition, the water chamber on the outlet side of the heat exchanger tube is connected to the pressure suppression pool via a condensed water discharge pipe and a steam discharge pipe, so that a portion of the steam is condensed in the water of the pressure suppression pool, so that the heat exchanger can reduce the amount of heat exchanged in
It becomes possible to downsize the heat exchanger structure.

In addition, since the non-condensable gas contained in the steam can be reliably discharged through the steam exhaust pipe, contact between the inner surface of the heat transfer tube and the steam is not inhibited, and good heat exchange is always possible. Be able to do it.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of the residual heat removal device for a boiling water reactor according to the present invention, Fig. 2 is a sectional view showing an enlarged main part of Fig. FIG. 4 is a schematic sectional view showing another embodiment of the invention, and FIG. 4 is a schematic configuration diagram showing a conventional example. 21... Reactor pressure vessel, 22... Piping, 24...
・Heat exchanger, 25...Cylinder, 26...Heat transfer tube, 27
...Inlet side water chamber, 28...Outlet side water chamber, 30...
Pressure control valve, 31...excess steam introduction pipe, 31a...
Main steam pipe, 32... Pressure suppression pool, 33... Condensed water discharge pipe, 34... Pool water, 35... Steam discharge pipe.

Claims (1)

[Claims] 1. A heat exchanger type heat exchanger is connected to a pipe for circulating reactor water led out from a reactor pressure vessel, and the heat exchanger is connected to a main steam pipe via a pressure control valve, In the residual heat removal device for a boiling water reactor that can selectively perform a reactor water residual heat removal operation during reactor shutdown and an excess steam condensation operation during reactor operation, the heat transfer tube of the heat exchanger Pipes for reactor water circulation and excess steam introduction pipes from the main steam pipe are connected to the water chamber on the inlet side of the heat exchanger tube, and the inside of the heat exchanger tube is used as a flow path for reactor water and surplus steam. A residual heat removal device for a boiling water reactor, characterized in that a chamber is connected to a pressure suppression pool through a condensed water discharge pipe and a steam discharge pipe. 2. The boiling water type atom according to claim 1, wherein the heat exchanger is of a horizontal type, and the condensed water discharge pipe has a tank for controlling the water level in the water chamber on the outlet side of the heat transfer tube in the middle thereof. Furnace residual heat removal device.