JP2589630Y2 - Core cooling system for light water reactor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core cooling device for a light water reactor.

[0002]

2. Description of the Related Art In general, in light water reactors, as a safety facility assuming a large-scale loss of coolant accident,
A cooling water storage tank is installed outside the reactor containment vessel, and when the reactor water level inside the reactor pressure vessel falls below the warning level, the level is detected by a liquid level gauge, etc. A cooling device (emergency core cooling device) for supplying water from the cooling water storage tank to the core by driving the pump is employed. In this case, since the piping from the cooling water storage tank to the reactor pressure vessel is arranged so as to penetrate the wall surface of the containment vessel, an isolation valve is arranged near the penetrating portion. By providing the isolation valve in this way, the piping system inside and outside the reactor containment vessel can be separated, and when a failure such as breakage occurs in each piping, the isolation valves are closed to thereby mutually prevent the failure. It is designed to avoid impact.

[0003]

However, in the above-described cooling device, when the piping is broken outside the containment vessel, the reactor is not closed until the isolation valve is closed. Because the pressure inside the pressure vessel may cause leakage of steam containing radioactive materials inside the reactor pressure vessel, a detailed breakage detection system that monitors every part of the piping system to improve safety And the responsiveness and reliability of the isolation valve, which should be closed in the event of an emergency, had to be improved.

The present invention has been made in view of the above-mentioned circumstances, and eliminates piping penetrating a reactor containment vessel, thereby improving the reliability, safety, etc. of the core cooling of a light water reactor. It is intended to provide a device.

[0005]

In order to achieve the above-mentioned object, the present invention provides a method for cooling a reactor core by injecting cooling water into the reactor pressure vessel when the reactor water level of the reactor pressure vessel falls below the warning level. A cooling water storage tank having at least a part of a partition wall housed in a reactor containment containing a reactor pressure vessel and having a liquid level above a reactor water level; and A water supply pipe arranged in a state penetrating the partition wall of the storage tank and connected to the reactor pressure vessel, and water is supplied by a water level detecting means attached at an intermediate position of the water supply pipe and detecting a warning water level of the reactor pressure vessel. The present invention provides a core cooling apparatus for a light water reactor, comprising: an operating valve for opening a pipe for use.

[0006]

According to the core cooling system for a light water reactor according to the present invention, when the water level detecting means detects that the reactor water level falls below the warning level, the operating valve connected to the water level detecting means is opened. Then, the water supply pipe to which the operating valve is attached is opened. Since the cooling water storage tank has a liquid level above the reactor water level, the cooling water falls due to a head difference and is injected into the reactor pressure vessel through a water supply pipe. Further, since the cooling water storage tank has a part of the partition wall accommodated in the reactor containment vessel, the water supply pipe arranged through the partition wall and connected to the reactor pressure vessel is Even if the water supply pipe is broken inside the containment vessel and the water supply pipe is broken, the cooling water leaking from the broken part and the steam etc. ejected from the reactor pressure vessel are It will be stored inside the reactor containment vessel.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling system for a light water reactor according to the present invention will be described below with reference to FIGS. In these figures, reference numeral 1 denotes a reactor containment vessel, 2 denotes a reactor pressure vessel, 3 denotes a suppression pool,
10 is a core cooling device, 11 is a cooling water storage tank, 12 is a water supply pipe, 13 is a pump, 14 and 15 are hydraulically operated valves (operating valves), 16 is a stop valve, 17 is a check valve, and 18 is a pressure relief valve. A valve, 19 is a pressure relief line, 20 and 21 are casings, 22 and 23 are valve bodies, 24 and 25 are diaphragm portions, and 26 is a water level detecting means.

[0008] The reactor containment vessel 1 has a reactor pressure vessel 2 disposed therein, and has a suppression pool 3 for suppressing internal pressure at a lower portion surrounding the reactor pressure vessel 2. .

As shown in FIG. 1, the cooling water storage tank 11 is a closed vessel disposed above the reactor containment vessel 1 and has an opening provided in the reactor containment vessel 1. 1a is mounted so as to close it, and a part of the wall surface (partition wall) 11a is disposed inside the reactor containment vessel in a housed state. The tank liquid level B of the cooling water storage tank 11 is set to be always higher than the reactor water level A of the reactor pressure vessel 2. The cooling water storage tank 1
One water supply pipe 12 penetrating the wall surface of the reactor pressure vessel 2 and one pressure relief line 19
Are disposed in a penetrating state. Two of the water supply pipes 12 are cooling water injection lines 12 a for supplying the cooling water in the cooling water storage tank 11 to the reactor pressure vessel 2, and the other two are provided.
This is to reduce the internal pressure of the reactor pressure vessel 2 to the cooling water storage tank 1
1 is a tank pressurization line 12b for transmitting the pressure to the tank.

The cooling water injection line 12a has one end connected to the liquid phase portion 11c of the cooling water storage tank 11 and the other end disposed above the core 2a in the reactor pressure vessel 2. A stop valve 16 is provided near the wall surface 11a of the cooling water storage tank 11 at an intermediate position of the cooling water injection line 12a, and a hydraulically actuated valve 14, which will be described later, is mounted in the reactor pressure vessel 2. .

One end of the tank pressurizing line 12b is disposed in the gas phase portion 11b of the cooling water storage tank 11, and the other end is disposed above the core 2a similarly to the cooling water injection line 12a. In the middle of the tank pressurizing line 12b, near the wall surface 11a of the cooling water storage tank 11,
A check valve 17 for preventing flow from the cooling water storage tank 11 in the direction of the reactor pressure vessel 2 is attached, and a hydraulically actuated valve 15 described later is attached inside the reactor pressure vessel 2.

The pressure relief line 19 has one end connected to the cooling water storage tank 11 similarly to the tank pressurizing line 12b.
And the other end is disposed in a state of landing on the suppression pool 3 in the containment vessel 2. A pressure relief valve 18 is mounted at a midway position of the pressure relief line 19.
Is opened when the pressure in the cooling water storage tank 11 exceeds a predetermined pressure so that the steam in the cooling water storage tank 11 escapes to the suppression pool 3 and is condensed in the suppression pool 3. Has become.

Two pumps 13 are arranged outside the reactor pressure vessel 2 and are connected in parallel with each other by connecting an inlet 13a and an outlet 13b. The suction port 13a of the pump 13 is provided inside the wall of the reactor pressure vessel 2 through the wall thereof, and the discharge port 13b is also provided inside the wall of the reactor pressure vessel 2 through the wall. It is connected to a hydraulic valve 14. The suction port 13a is disposed at the height of the warning water level A 'of the reactor pressure vessel 2. When the reactor water level A falls below the warning water level A', the reactor water is no longer sucked into the pump 13 and the discharge pressure is reduced. Is reduced, whereby a water level detecting means 26 for detecting that the reactor water level A has fallen below the warning level A 'is formed. FIG.
Reference numeral 13c denotes a check valve for preventing backflow to the pump 13.

The hydraulic valves 14 and 15 are fixed inside the reactor pressure vessel 2 and, for example, as shown in FIGS. 2 and 3, casings 20 and 21 connected to a discharge port 13 b of the pump 13. And valve bodies 22 and 23 for opening and closing the water supply pipe 12 connected to the internal space of the reactor pressure vessel 2.
And the pump 13 disposed inside the casings 20 and 21.
And the diaphragm portions 24 and 25 for driving the valve bodies 22 and 23 by the discharge pressure of the diaphragm.

[0015] The diaphragm portions 24 and 25 are connected to the inner space of the casings 20 and 21 by the discharge port 1 of the pump 13.
3b and open side spaces 20b and 21b opened inside the reactor pressure vessel 2.
Bellows 24a and 25a and plate 2 partitioned into
4b and 25b, and the bellows 24a and 25a are attached to the pump side space 20a and 25b on the plates 24b and 25b.
Compression coil springs 24c and 25c for urging in the direction of 21a
And the valve elements 18 and 19 are attached. In a free state in which the discharge pressure of the pump 13 does not act, the valve bodies 22 and 23 are moved by the compression coil springs 20c and 21c in a direction to open the water supply pipe 12. In FIG. 2, reference numeral 24d
Is a bellows for isolating the valve body 22 from the pump side space 20a in an airtight state.

The core cooling device 11 configured as described above
The operation state of is described below. In the normal operation state of the reactor, the reactor water level A inside the reactor pressure vessel 2 is:
It is set to be in a certain state. In this state, since the pump 13 has landed on the reactor water at the suction port 13b, by operating the pump 13,
Generates a constant discharge pressure. The discharge pressure is transmitted to the hydraulic pressure operated valves 14 and 15 and generates a pressure difference between the inside and outside of the diaphragm portions 24 and 25 disposed inside the hydraulic pressure operated valves 14 and 15. That is, the pressure in the pump-side spaces 20a and 21a defined by the diaphragm portions 24 and 25 is increased by the discharge pressure, and a force acts in a direction to compress the compression coil springs 24c and 25c. And bellows 24a
The valve bodies 22 and 23 hold the water supply pipe 12 in a closed state by the balance of the forces due to the 24d and 25a, the compression coil springs 24c and 25c, and the pressure difference. In this state, the cooling water stored in the cooling water storage tank 11 is blocked by the hydraulic valve 15 so as not to be injected into the reactor pressure vessel 2, and the internal pressure of the reactor pressure vessel 2 is reduced. , The cooling water storage tank 11
Will not be communicated to.

At this time, the internal pressure of the cooling water storage tank 11 is substantially atmospheric pressure, and the internal pressure of the reactor pressure vessel 2 is a normal operating pressure (for example, 70 kg / cm).
² g), the pressure difference is
A force is generated in the direction in which the cooling water injection line 12a is closed by acting on the valve body 23, and the cooling water is stably held so as not to be injected in the normal operation state.

Next, the core cooling device 1 in the case where the reactor water level A drops due to some cause and falls below the warning water level A '.
1 will be described. When the reactor water level A falls below the alert water level A ', the suction port 13a of the pump 13 is exposed above the reactor water and the discharge pressure of the pump 13 decreases. The pressure in the pump-side space 20a and the pressure in the open-side space 20b of the valve 14 are both equal to the internal pressure of the reactor pressure vessel 2, the hydraulic valve 14 is free, and the tank pressurizing line 12b is opened. . At this time, if a sharp pressure rise occurs in the cooling water storage tank 11,
When the pressure relief valve 18 is opened, the internal pressure of the cooling water storage tank 11 is maintained so as not to exceed the set pressure.

In the hydraulic valve 15, the hydraulic valve 1
4, the internal pressure of the casing 21 becomes the internal pressure of the reactor pressure vessel 2. However, due to the pressure difference applied to the valve 23, the casing 21 is not immediately brought into the free state, but is kept in the closed state for a while. You. Then, the internal pressure of the reactor pressure vessel 2 is transmitted to the cooling water storage tank 11 through the tank pressurizing line 12b, the internal pressure of the cooling water storage tank 11 is increased, and the cooling water of the cooling water injection line 12a is added. By being pressed, the pressure difference acting on the valve body 23 is reduced, and the hydraulic valve 15 is opened.

Here, the tank level B of the cooling water stored in the cooling water storage tank 11 is set to be higher than the reactor water level A of the reactor pressure vessel 2. The cooling water drops due to the head difference and is injected into the reactor core 2a through the cooling water injection line 12a. The cooling water injected in this way makes up for the lost reactor water and cools the core 2a.

When the pump 13 breaks down, the discharge pressure acting on the hydraulic valves 14 and 15 is lost, and the core cooling is performed in the same manner as when the reactor water level A falls below the warning level A '. The device 10 will operate. However, in such a case, it is unnecessary to operate the core cooling device 10. Therefore, by disposing the two pumps 13 in parallel, one pump 13 may be broken. Also, the discharge pressure acting on the hydraulic valves 14 and 15 is not lost, so that the hydraulic valves 14
15 is kept closed. In this case, the suction ports 13a of the two pumps 13 are connected, and the discharge pressure decreases at the same time as the furnace water level A lowers. Therefore, the core cooling device 10 functions in the same manner as when one pump 13 is used. Will do.

Here, assuming that the cooling water injection line 12a and the tank pressurizing line 12b connecting the reactor pressure vessel 2 and the cooling water storage tank 11 are broken, these pipes are connected to the reactor containment vessel 1 Therefore, the steam and the like containing the radioactive material in the reactor pressure vessel 2 are stored in the reactor containment vessel 1 and safety is improved.

<Other Embodiments> In the core cooling device 10 of the light water reactor according to the present invention, the following technology can be adopted. The number of pumps 13 connected in parallel with the hydraulic valves 14 and 15 is set to an arbitrary number of two or more. Another actuator such as a cylinder is used in place of the diaphragm portions 24 and 25 made of bellows of the hydraulic valves 14 and 15. Instead of the water level detecting means 26 formed by disposing the suction port 13a of the pump 13 at the alert water level A ', a water level detecting means such as a liquid level meter is used. Instead of the water pressure operated valves 14 and 15, a water level detecting means 26
Use other actuated valves driven by signals from The entire cooling water storage tank 11 is housed inside the containment vessel.

[0024]

As described above, according to the light water reactor core cooling apparatus of the present invention, the cooling water storage tank in which the partition wall is housed inside the reactor containment vessel, and the cooling water storage tank A water supply pipe connected to the reactor pressure vessel through the partition wall of the tank; and an operating valve for opening the water supply pipe by a water level detecting means for detecting a warning water level. Steam or the like containing radioactive substances leaking from the reactor pressure vessel when the piping is broken or the like is stored in the containment vessel, which has the effect of improving safety.

[Brief description of the drawings]

FIG. 1 is a model diagram showing one embodiment of a core cooling device of a light water reactor according to the present invention.

FIG. 2 is a longitudinal sectional view showing a hydraulic valve connected to a tank pressurizing line of the core cooling device of FIG. 1;

FIG. 3 is a longitudinal sectional view showing a hydraulic valve connected to a cooling water injection line of the core cooling device of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor containment vessel 2 Reactor pressure vessel 3 Suppression pool 11 Cooling water storage tank 11a Wall surface (partition wall) 11b Gas phase part 11c Liquid phase part 12 Water supply pipe 12a Cooling water injection line 12b Tank pressurization line 13 Pump 13a Suction Port 13b Discharge port 13c Check valve 14.15 Water pressure operated valve 16 Stop valve 17 Check valve 18 Pressure relief valve 19 Pressure relief line 20 ・ 21 Casing 20a ・ 21a Pump side space 20b ・ 21b Open side space 22 ・ 23 Valve body 24/25 Diaphragm 24a / 24d / 25a Bellows 24b / 25b Plate 24c / 25c Compression coil spring A Furnace water level A 'Warning water level B Tank liquid level

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaru Togasaki 1 Shin-Nakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Ishikawajima-Harima Heavy Industries Co., Ltd. Yokohama No. 1 Factory (56) References , A) JP-A-62-212594 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G21C 15/18

Claims (1)

(57) [Scope of request for utility model registration] An apparatus for cooling a reactor core by injecting cooling water into a reactor pressure vessel when a reactor water level of the reactor pressure vessel falls below a warning level, wherein the reactor houses the reactor pressure vessel. A cooling water storage tank having at least a part of the partition wall housed therein and having a liquid level above the reactor water level; and a reactor pressure which is disposed in a state penetrating the partition wall of the cooling water storage tank. A water supply pipe connected to the vessel, and an operating valve attached at an intermediate position of the water supply pipe to open the water supply pipe by a water level detecting means for detecting a warning water level of the reactor pressure vessel. Core reactor for light water reactors.