JPS6151705B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pressure relief safety device for a nuclear reactor that is connected to a main steam pipe of a nuclear reactor and is used to release high pressure steam generated in the reactor at abnormal pressures to a suppression pool.

Generally, a pressure relief safety valve is installed in the main steam pipe of a nuclear reactor, and when the pressure in the reactor becomes abnormally high, the safety valve automatically opens to suppress the reactor pressure and The emergency core cooling water system injects cooling water stored outside the reactor into the upper part of the reactor core to maintain the integrity of the reactor body.

That is, as shown in FIG. 1, a main steam pipe 3 is attached to a pressure vessel 2 containing a reactor core 1, and an isolation valve 4 is provided on this main steam pipe 3. Steam is fed to the turbine.

On the other hand, a pressure relief safety valve 5 is attached to the main steam pipe 3 before the isolation valve 4, and an operating cylinder 6 is connected to the safety valve 5. Further, an exhaust pipe 7 is connected to the safety valve 5, and this exhaust pipe 7 is connected to a suppression pool 8. When the inside of the reactor becomes abnormally high pressure, the safety valve 5 is connected to the high pressure main steam in the main steam pipe 3 or The operating cylinder 6, which is pneumatically operated, opens in response to a detection signal from a pressure detector installed around the reactor, and high-pressure main steam is discharged to the suppression pool 8.

Usually, four main steam pipes 3 are provided, and each main steam pipe 3 is provided with a total of 10 to 20 safety valves 5, and each safety valve 5 is formed at the junction of the exhaust pipe 7 and the main steam pipe 3. It has a valve body 10 that opens and closes a valve seat 9,
A stem 11 is connected to the valve body 10, and the stem 11 passes through a casing 12. A compression spring 13 is housed in the casing 12.
3, the valve body 10 is biased to be in a normally closed state.

A head plate 11a is attached to the upper end of the stem 11, and the push-up piece 14a of the operating lever 14, which rotates around the fulcrum P, is in contact with the lower side of the head plate 11a. At the opposite end of the fulcrum P, a piston rod 15 of the working cylinder 6 is attached.
Piston 1 is attached to the upper end of the rod, and a piston 1 is attached to the lower end of the rod.
6 is slidably mounted within a cylinder 17, and this piston 16 is biased in the direction of retracting the rod 15 by a compression spring 17a.

The cylinder 17 has a conduit 18 and a valve 19.
Working gas (N ₂ ) is supplied through the valve 19.
The reactor is designed to be opened by a signal from a pressure detector installed around the reactor when the pressure inside the reactor becomes high.

A limit switch 2 is installed on the top of the rod 15.
The actuator 20a of No. 0 comes into contact with the rod 15, thereby detecting the vertical movement of the rod 15. The limit switch 20 detects the open/closed state of the valve body 10 through the vertical movement of the rod 15. However, this limit switch 20
This ensures that when the actuating cylinder 6 is actuated and the rod 15 is extended to open the valve body 10, the valve body 10 is opened.
However, when the supply of working gas to the working cylinder 6 is stopped and the rod 15 is retracted, the head of the stem 11 and the push-up piece 14a are in contact connection, and the stem 11 is forcibly moved. Since it is not pressed down, a close signal may be sent to the limit switch 20 even if the valve body 10 remains open.

As described above, unless the limit switch 20 accurately grasps the open/closed state of the valve, it is difficult to perform operations such as replenishing the flow of coolant in the furnace, making it an incomplete safety device.

In view of the above, the present invention provides a pressure relief safety device for a nuclear reactor that can accurately detect the open/closed state of a safety valve, take appropriate measures in an emergency, and improve the safety of a nuclear reactor. The purpose is to

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 3, a pressure relief safety valve 29 of the present invention is shown.
At the joint between the exhaust pipe 7 and the main steam pipe 3,
A valve seat 30 is formed, and a valve body 31 is mounted on this valve seat 30.
The valve body 31 is attached to the lower end of the stem 32. The stem 32 is housed in a casing 33, and a flange 32a is attached to the middle of the stem. A compression spring 34 is disposed between the flange 32a and a step 33a formed in the casing. The valve body 31 is biased to a normally closed state.

The upper end of the stem 32 is pivotally connected to the vicinity of the right end of the actuating lever 35 by a pin 36.
The right end of 5 is the shaft 3 fixed to the upper part of the casing 33.
7, the operating lever 35 extends outward through the casing upper opening 33b, and a locking pawl 38 is fixed near the left end thereof. This locking claw 38
A pin 39 protruding from the upper end of the piston rod 15 comes into contact with it from below, and a piston 16 is attached to the lower end of the rod 15. This piston 16 is slidably housed in a cylinder 17, and this Working gas is injected into the cylinder via a conduit 18 and a valve 19.

A limit switch 20 is provided on the left side of the operating lever 35, and its actuator 20a is in contact with the right end surface of the operating lever.

Next, the effect will be explained.

When the reactor pressure increases, a pressure detector installed around the reactor operates, opens the valve 19, and sends working gas into the cylinder 17. This results in
The piston 16 moves upward in the figure and the actuating lever 35
is rotated clockwise in the figure around the shaft 37. Therefore, the stem 32 moves upward while compressing the compression spring 34, causing the valve body 31 to separate from the valve seat 30. In this way, the valve is opened and closed, and the steam in the main steam pipe 3 is exhausted to the suppression pool 8.

On the other hand, the rotation of the operating lever 35 is detected by the limit switch 20, which lights up a valve open indicator lamp (not shown).

When the reactor pressure decreases, the valve 19 closes and the piston 16 returns to its original position by the action of the compression spring 17a, and the rod 15 descends independently of the movement of the operating lever 35. However, when the main steam pressure becomes less than the withstand pressure limit of the pressure vessel boundary, the stem 32 also descends due to the action of the compression spring 34, and the valve body 31 comes into contact with the valve seat, closing the valve.
When the stem 32 descends, the stem 32 and the operating lever 35 are connected by the pin 36, so the operating lever 35 rotates counterclockwise in the figure, and the movement of the operating lever 35 is detected and displayed by the limit switch. be done.

In this case, if the ratio of the distance between the shaft 37 and the pin 36 and the distance between the shaft 37 and the pin 39 is set to about 1:5, the required movement distance of the stem 32 of 5 mm will be at the detection position of the limit switch 20. Since the width is increased to approximately 25 mm, the detection span of the limit switch 20 is sufficient, and the open/closed state of the valve can be reliably detected.

Next, we will explain the case where the reactor pressure exceeds the pressure limit of the reactor pressure vessel boundary.
The main steam pressure overcomes the pressing force of the compression spring 34 and pushes up the valve body 31 and stem 32. Then, the actuating lever 35 rises independently of the rod 15 of the actuating cylinder 6, and its movement causes the limit switch 20 to move upward.
is detected and displayed.

Conversely, when the reactor pressure decreases and falls below the pressure limit of the pressure vessel boundary, the compression spring 3
4, the stem 32 and the actuating lever 35
This lowering of the operating lever 35 is detected and displayed by the limit switch 20.

In this way, the movement of the stem 32 is controlled by the operating lever 3.
If a detection member (limit switch 20) is used to detect and display the safety valve via 5, even if a valve malfunctions, such as a stuck valve, the safety valve will be reliably displayed as open or closed, allowing the operator to take appropriate measures. This has the effect of preventing serious accidents such as leakage of cooling water and steam inside the reactor.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the reactor pressure relief system, Figure 2 is a schematic diagram of the conventional reactor pressure relief safety device,
and FIG. 3 are longitudinal sectional views of the nuclear reactor pressure relief safety device of the present invention. 6... Operating cylinder, 15... Piston rod, 20... Limit switch, 29... Pressure relief safety valve, 31... Valve body, 32... Stem, 35
...Actuation lever, 36, 39...Pin, 37...
Shaft, 38...Latching claw.

Claims (1)

[Claims] 1. A pressure relief safety valve that is attached to the main steam pipe and opens to discharge main steam to a suppression pool when the pressure inside the reactor becomes abnormally high, and the pressure inside the reactor. A pressure relief safety device for a nuclear reactor, comprising an actuating cylinder that is activated by a signal from a pressure detector that detects pressure to open the safety valve when the pressure inside the reactor is high; One end of an operating lever that swings around a fixed fulcrum for interlocking the operation of the operating cylinder and the opening and closing of the safety valve is pivotally connected to the biased valve stem, and the other end of the operating lever is connected to the operating cylinder. The actuating lever is engaged with the piston rod so as to forcefully rotate the actuating lever only when the rod moves in the direction of opening the safety valve, and the movement of the actuating lever is detected and displayed by a detection member. Pressure relief safety device for nuclear reactors. 2. The nuclear reactor according to claim 1, characterized in that a pin is attached to the piston rod of the operating cylinder, and a locking pawl is attached to the operating lever, and the locking pawl is connected to the pin in contact with the pin. Pressure relief safety device.