JPH10148692A - Emergency injection device for cooling water for nuclear reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely emergency-inject a plenty of emergency cooling water necessary for core cooling into reactor vessel by forming pressure-equalizing path of which both ends are connected to a pair of openings provided on cylindrical wall of a volute diode. SOLUTION: A pair of openings 9, 9 are punched in a cylindrical wall of a volute diode 5 putting an outflow hole 5d in between. To these openings 9, 9, a pressure equalizing path 10 connected at both ends is formed. If the pressure in a reactor primary cooling system pipe largely lowers, a check valve opens and emergency cooling water 6 is injected by way of the volute diode 5. Even if pressure difference due to production error of the volute diode 5 is caused, the pressure difference is cancelled by way of the connection path 11 in the equalizing path 10 connected to the openings 9, 9. Therefore, the flow reduction of emergency cooling water at the injection initiation caused by the production error of the volute diode 5 is prevented and a plenty of emergency cooling water necessary for core cooling and the like can be surely emergency-injected in the reactor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for urgently injecting emergency cooling water into a reactor vessel when an accident such as a breakage of a primary cooling system piping of a nuclear reactor occurs.

[0002]

2. Description of the Related Art As an apparatus for urgently injecting emergency cooling water into a reactor vessel of a pressurized water reactor, Japanese Patent Publication No. 6-4406 is disclosed.
There is known an emergency water injection device disclosed in Japanese Patent Publication No. 0-203. This emergency water injection device has a water injection pipe for injecting emergency cooling water into the reactor primary cooling system piping, a check valve provided in the middle of this water injection pipe to prevent backflow, and an upstream side of this check valve. A closed-type pressure accumulating water injection tank is provided, and emergency cooling water is stored inside the pressure accumulating water injection tank. The emergency cooling water is pressurized by the gas sealed in the pressure accumulating water injection tank, and the pressure is slightly lower than the pressure of the primary cooling system of the reactor. Further, this emergency water injection device has a spiral diode inside the accumulator water injection tank, and has a structure in which the amount of emergency cooling water injected is switched from a large flow rate to a small flow rate by the spiral diode.

FIGS. 4 and 5 show the structure of a spiral diode used in the above-mentioned emergency water injection device. In the drawing, reference numeral 41 denotes a spiral diode. The spiral diode 41 is a cylindrical body 42 provided in a pressure accumulating water tank (not shown).
And a pair of end plates 4 for closing the openings at both ends of the cylindrical body 42.
3 and 44, and an outlet 45 is formed in one of the end plates 43 and 44 (for example, the end plate 44). One end of a water injection pipe 46 is connected to the outlet 45,
The other end of 6 is connected to a primary cooling system piping (not shown). Outlet ends 47a and 48a of inflow pipes 47 and 48 are connected to the cylindrical body 42 of the spiral diode 41 so as to face each other. Of these inflow pipes 47, 48, the inflow pipe 47
The inlet 47b is opened at a lower portion in the accumulator water injection tank, and the cooling water flowing into the spiral diode 41 from the inlet 47b flows along the inner wall surface of the cylindrical body 42. On the other hand, the inlet 48b of the inflow pipe 48 is open at the lower part in the accumulator water injection tank. It flows in the opposite direction.

In the emergency water injection device provided with such a spiral diode 41, when the pressure of the primary cooling system of the reactor decreases due to a breakage of the primary cooling system piping or the like, the check valve opens to open the inside of the accumulator injection tank. Cooling water is injected into the reactor primary cooling system piping via the spiral diode 41 and the injection pipe 46. Here, at the initial stage of water injection into the reactor primary cooling system piping, the cooling water level in the accumulator water injection tank is higher than the inlet 48b of the inflow pipe 48,
The emergency cooling water flows from both of the inflow pipes 47 and 48. This is because the emergency cooling water flowing into the spiral diode 41 from the inflow pipe 48 and the spiral diode 41
This is to prevent the generation of a vortex by colliding with the emergency cooling water that has flowed into the tank, and to inject a large amount of necessary cooling water. The impinging cooling water forms a non-swirl flow 49 flowing linearly toward the outflow port 45, and forms swirl sub-flows 50 on both sides of the non-swirl flow 49. On the other hand, in the latter stage of the injection of water into the primary cooling system piping of the reactor, the cooling water level in the accumulator injection tank is lower than the inlet 48b of the inlet pipe 48 because a large amount of cooling water is not required. Therefore, the emergency cooling water flows into the spiral diode 41 only from the inflow pipe 47. At this time, the emergency cooling water flowing into the spiral diode 41 is, as shown in FIG.
The swirling flow 51 flowing along the inner peripheral surface of the nozzle is formed, and the outflow resistance increases. Therefore, the amount of cooling water flowing out of the outlet 45 and injected into the primary system pipe is reduced to a flow cross-sectional area ratio of the inlet pipe or less.

[0005]

Such a cooling water emergency injection device utilizes a spiral diode 41 provided inside a pressure accumulating water injection tank, and requires a required flow rate change pattern, that is, without using a dynamic device such as a pump. Achieving a flow rate change that switches the injection amount of emergency cooling water from a large flow rate to a small flow rate,
While it is possible to improve the reliability of the apparatus, it has the following problems. That is, in the above-mentioned emergency water injection device, for example, when there is a manufacturing error in the spiral diode 41 or when the flow of the emergency cooling water flowing into the spiral diode 41 is disturbed, the non-swirl flow 49 generated at the initial stage of the water injection is formed on both sides. The pressure balance of the formed swirl auxiliary flow 50 is lost, and the flow of the emergency cooling water flowing into the spiral diode 41 from the inflow pipes 47 and 48 becomes a swirl flow as shown in FIG. 7, and a necessary large amount of injected water is obtained. There was a problem that can not be. As a countermeasure to prevent such a decrease in the amount of water injected at the beginning of the water injection, it is conceivable to increase the size of the spiral diode. In this case, however, the amount of water injected at the latter stage of the water injection also increases.
For this reason, in the latter stage of the injection of a small amount of emergency cooling water for a predetermined time, the pressure accumulating injection tank must be increased in size in order to prevent the depletion of the cooling water, resulting in an increase in cost. The present invention has been made in order to solve such a problem, and it is intended to prevent a decrease in a flow rate of cooling water at an initial stage of water injection due to a manufacturing error of a spiral diode and to provide a large amount of emergency necessary for core cooling and the like. It is an object of the present invention to provide an emergency cooling water injection device for a nuclear reactor that can surely inject cooling water into a nuclear reactor vessel.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a pressure-accumulating water injection tank connected to a reactor primary cooling system pipe through a communication pipe provided with a check valve, and a pressure-accumulating water injection tank. A spiral diode provided in the tank and having an outlet connected to the communication pipe;
A first cooling water inlet pipe connected to the inflow port and having an inlet opened at a relatively lower position in the pressure accumulating water injection tank;
A second cooling water inlet pipe connected to a second inlet of the spiral diode and having an inlet opened at a relatively upper position in the pressure accumulating water injection tank; A spiral diode, wherein the first and second inflow ports are tangentially opposed to each other and open to a cylindrical wall;
The end of the cylindrical wall is closed and at least one of the end plates has the outflow port opened. At least one of the cylindrical walls of the spiral diode has the first inflow-side space and the space with the outflow port interposed therebetween. A pair of openings are respectively opened in the space near the second inflow port, and equalizing passages having both ends connected to these openings are formed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
An embodiment of the present invention will be described. FIG. 1 is a schematic diagram of a cooling water emergency injection device according to an embodiment of the present invention,
As shown in FIG. 1, the cooling water emergency injection device 1 includes a communication pipe 2 for injecting emergency cooling water into a reactor primary cooling system pipe (not shown). The communication pipe 2 has a check valve 3 for preventing backflow.
And a pressure accumulating water injection tank 4 is provided upstream of the check valve 3. The pressure accumulating water injection tank 4 has a sealed structure, and a spiral diode 5 as a flow rate switching means is provided inside the pressure accumulating water injection tank 4.
Emergency cooling water 6 is stored inside the pressure accumulating water injection tank 4.
The pressure is maintained at a predetermined value by a pressurized gas such as a nitrogen gas supplied to the inside.

The spiral diode 5 will be described with reference to FIGS. 2 and 3. The spiral diode 5 has a cylindrical body 5a forming a peripheral wall of the diode 5. The cylindrical body 5a is closed at both ends in a liquid-tight manner by a lower end plate 5b and an upper end plate 5c, and one of the end plates 5b, 5c (for example, the lower end plate 5b) is particularly shown in FIG. An outlet 5d for injecting the emergency cooling water 6 into the communication pipe 2 is provided so that the emergency cooling water 6 can be injected.

A cylindrical body 5a forming the peripheral wall of the spiral diode 5 has an emergency cooling water 6 inside the spiral diode 5.
The outlet ends 7a, 8a of the first cooling water introduction pipe 7 and the second cooling water introduction pipe 8 for injecting the water are connected. These outlet ends 7a and 8a are opposed to each other in the tangential direction of the cylindrical body 5a and open. The emergency cooling water flowing into the spiral diode 5 from the outlet end 8a of the second cooling water introduction pipe 8 is supplied to the first cooling water introduction pipe. Emergency cooling water that has flowed into the spiral diode 5 from the outlet end 7a of the cooling water introduction pipe 7 is collided with the emergency cooling water. And
As shown in FIG. 1, the inlet end 7b of the first cooling water introduction pipe 7
Is open at the lower part of the accumulator injection tank 4.
The inlet end 8b of the cooling water introduction pipe 8 is opened at the upper part in the pressure accumulating water injection tank 4.

As shown in FIG. 3, a pair of apertures 9, 9 are formed in the peripheral wall of the spiral diode 5 with an outlet 5d provided in the lower end plate 5b interposed therebetween. Both ends of a pressure equalizing tube 10 provided outside the spiral diode 5 are connected to these openings 9, 9, and inside the pressure equalizing tube 10, a right side formed on the right side with the outlet 5 d as a center. A communication passage 11 is formed to keep the left internal space 5L formed on the left side around the outflow port 5d in the same pressure state as the internal space 5R.

In such a configuration, when the pressure in the primary cooling system piping of the reactor is greatly reduced, the check valve 3 is opened, and the emergency cooling water 6 in the accumulator injection tank 4 is connected to the spiral diode 5 and the communication pipe 2. After that, water is injected into the reactor primary cooling system piping. Here, even if a pressure difference due to a manufacturing error of the spiral diode 5 occurs, the right internal space 5R of the spiral diode 5
And the left internal space 5L through a communication passage 11 formed inside a pressure equalizing tube 10 to which a pair of openings 9, 9 provided in a peripheral wall portion of the spiral diode 5 with an outlet 5d interposed therebetween. The difference is negated. Therefore, it is possible to prevent a decrease in the flow rate of the emergency cooling water at the initial stage of water injection due to a manufacturing error of the spiral diode 5 and to surely urgently inject a large amount of emergency cooling water necessary for core cooling into the reactor vessel. Can be.

[0012] In one embodiment of the present invention described above,
Both ends of the pressure equalizing tube 10 are connected to openings 9, 9 provided in the peripheral wall of the spiral diode 5 to communicate the right internal space 5 </ b> R and the left internal space 5 </ b> L of the spiral diode 5. May have a double wall structure, and a communication path may be formed between the outer wall and the inner wall to communicate the right internal space 5R and the left internal space 5L of the spiral diode 5 with each other.

[0013]

As described above, according to the present invention,
It is possible to prevent a decrease in the flow rate of the cooling water in the initial stage of the water injection due to a manufacturing error of the spiral diode and to surely urgently inject a large amount of emergency cooling water necessary for cooling the core into the reactor vessel.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cooling water emergency injection device according to an embodiment of the present invention.

FIG. 2 is a side view of the spiral diode shown in FIG.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a longitudinal sectional view of a spiral diode in a conventional cooling water emergency injection device.

FIG. 5 is a sectional view taken along the line BB of FIG. 4;

FIG. 6 is a view for explaining a flow of emergency cooling water flowing into the spiral diode shown in FIG. 4;

FIG. 7 is a diagram for explaining a problem of a conventional cooling water emergency injection device.

[Explanation of symbols]

 2 Communication pipe 3 Check valve 4 Accumulated water injection tank 5 Spiral diode 5a Cylindrical body 5b Lower end plate 5c Upper end plate 5d Outlet 5R Right internal space 5L Left internal space 6 Emergency cooling water 7 First cooling water introduction pipe 8 second cooling water introduction pipe 9 opening 10 equalizing pipe 11 communication passage

Claims (1)

[Claims] An accumulator injection tank connected to a primary cooling system piping via a communication pipe provided with a check valve, and a spiral diode provided in the accumulator injection tank and having an outlet connected to the communication pipe. A first cooling water inlet pipe connected to a first inlet of the spiral diode and having an inlet opened at a relatively lower position in the pressure accumulating water tank, and a second inlet of the spiral diode. A second cooling water inlet pipe having an inlet opened at a relatively high position in the accumulator water injection tank, and wherein the spiral diode includes the first and second spiral diodes. The inflow port has a cylindrical wall that is opened tangentially facing and a pair of end plates that close the end of the cylindrical wall and open at least one of the outflow ports, and the cylindrical wall of the spiral diode has The outlet A pair of openings are respectively opened in the first inlet space and the second inlet space, and pressure equalizing passages having both ends connected to these openings are formed. Emergency water injection system for nuclear reactor.