JPH0478158B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hydraulic control unit, and more particularly to a hydraulic control unit that operates reliably during scram and can improve reliability.

2. Description of the Related Art For example, a hydraulic control unit used in a nuclear power plant is equipped with a double solenoid type pilot valve (hereinafter simply referred to as a pilot valve) that operates in an emergency to start a scram. This pilot valve has a pair of movable iron cores to which a valve body is attached, and a pair of solenoids that displace the movable iron cores by supplying a signal. Then, the pilot valve closes the air pressure supply to the diaphragm chamber only when the signals supplied to the pair of solenoids are in one combination, and displaces the movable iron core so as to switch to opening to the atmosphere, thereby reducing the pressure inside the diaphragm chamber. A movable iron core that opens the main valve, and when a signal of a combination other than the above is supplied, blocks the release of the atmosphere to the diaphragm chamber, supplies air pressure, and closes the main valve. It was designed to displace the .

A conventional mounting manner of the pilot valve having the above structure is shown in FIG. This figure is an enlarged view of the vicinity of the pilot valve 1 of the water pressure control unit. As shown in the figure, an air supply pipe 2 is connected to the upper part of the pilot valve 1, and a pressure guiding pipe 3 for introducing air pressure to a scram valve (not shown) is connected to the lower part. Further, the pilot valve 1 was attached to the water pressure control unit in a so-called horizontally attached state in which a pair of solenoids 4a and 4b were disposed horizontally with respect to a pressure guiding pipe 3 extending in the vertical direction.

Problems to be Solved by the Invention As described above, in the conventional water pressure control unit, the pilot valve 1 consists of a pair of solenoids 4a and 4b.
Since the mounting structure was such that the movable iron core was disposed horizontally, the moving direction of the movable iron core displaced by the solenoids 4a and 4b was also horizontal. Therefore, the movable core is placed horizontally on the cylinder inside the pilot valve 1, and when the movable core is displaced during scram, the movable core can move smoothly due to the large contact area between the movable core and the cylinder. There was a problem in that so-called stagnation, in which there was no displacement, was likely to occur. Furthermore, situations requiring scram rarely occur in nuclear power plants, and therefore the pilot valve 1 is extremely rarely activated. Therefore, the movable iron core maintains the position that closes the main valve for a long period of time. This causes a phenomenon of sticking between the movable core and the cylinder, which poses a problem in that the movable core may not be smoothly displaced during a scram. Furthermore, the design seismic intensity conditions for nuclear power plants are generally more strictly specified in the horizontal direction than in the vertical direction. Therefore, in the pilot valve 1 having a configuration in which the movable iron core is displaced in the horizontal direction as described above, the structure must be made stronger in order to satisfy the design seismic intensity conditions, and the shape of the pilot valve 1 must be made to perform its function. However, there were problems in that it was larger than necessary and the structure was complicated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a water pressure control unit that solves the above-mentioned problems by mounting the pilot valve vertically.

Means and Effects for Solving the Problems In order to solve the above problems, in the present invention, when power is cut off to a pair of solenoids during a scram, a pair of movable iron cores corresponding to the solenoids are displaced in a predetermined direction. In a hydraulic control unit equipped with a double solenoid type pilot valve configured to open the main valve, the double solenoid type pilot valve is oriented so that the direction of displacement of the movable iron core during scram is approximately vertical. I installed it like this. With the above configuration, the movable core moves in the falling direction during a scram, and malfunctions can be reduced.

Embodiment FIG. 2 shows an embodiment of the hydraulic control unit according to the present invention. The water pressure control unit 5 shown in the same figure is
It is roughly composed of a water pressure control section 6 and a scram section 7. The water pressure control unit 6 has four selection valves for normal control that control driving water, and is configured to drive the control rod in an appropriate direction by controlling these selection valves from a central operation panel. . The scram section 7 generally includes a pilot valve 8, a scram valve 9,
10, an accumulator 11, and the like. In normal times, the pilot valve 8 is closed, but in an emergency, the pilot valve 8 is opened and the air pressure in the scram valves 9 and 10 is released to the atmosphere via the pilot valve 8. The N ₂ gas in the N ₂ cylinder 11a is press-fitted into the cylinder 11b filled with emergency drive water and presses the piston inside the cylinder 11b, so that the emergency drive water flows into the control rod drive device and the control rod It is configured to rapidly insert.

The vicinity of the pilot valve 8 is shown enlarged in FIG. 1 and will be described in detail below. In the figure, reference numeral 12 denotes a ball valve as an air supply source, which is normally open and supplies air pressure to the pilot valve 8 via a joint 13 and piping 14. The pilot valve 8 is a double solenoid type pilot valve having a pair of solenoids 15a and 15b, and as shown in FIG. 3, a main valve 17 that opens during a scram is provided in a diaphragm chamber 16 formed inside. ing. This main valve 17 is provided corresponding to the solenoids 15a and 15b, and is displaced by a signal supplied to the solenoids 15a and 15b (the direction of displacement is indicated by arrows X ₁ and X ₂ in the figure).
The valve is configured to be opened and closed by the displacement of a pair of movable cores 18a and 18b (shown by ). Normally, the solenoids 15a and 15b are connected to the connectors 19a and 19.
is energized via b, and in this state,
In addition, when either one of the solenoids 15a and 15b is energized, the main valve 17 is displaced to the closing position (displaced in the direction of arrow _X1 in the figure), and the pilot valve 8 is moved from the ball valve 12. The air pressure of the T-shaped joint 20 and piping 21 shown in FIG.
It is supplied to scram valves 9 and 10 for emergency driving of control rods (not shown). Note that FIG. 3 shows a state in which the main valve 17 is closed.

During scram, solenoids 15 on both sides
Power supply to both a and 15b is stopped. In this state, the movable iron cores 18a and 18b are displaced to the position where the main valve 17 is opened (displaced in the direction of arrow _X2 in the figure), the main valve 17 is opened, and pressure is accumulated in the scram valves 9 and 10. Exhaust the air. Scram valve 9, 10
When the air pressure inside is exhausted and reduced, the _N2 cylinder 1
The high-pressure _N2 gas in 1a is press-fitted into the cylinder 11b filled with emergency drive water and presses the piston in the cylinder 11b, so that the emergency drive water flows into the control rod drive device and the control rod is inserted into the reactor.

Attention will now be paid to the mounting structure of the pilot valve 8. As shown in FIGS. 1 and 2, the water pressure control unit 5 of the present invention has a pilot valve 8 installed so that its pair of solenoids 15a and 15b are arranged in the vertical direction, and the installation direction is the same as in the scram. It is characterized in that the movable cores 18a and 18b are displaced in a substantially vertical direction (direction indicated by arrow _X2 in the figure). This causes the movable cores 18a, 18b to be displaced in the vertical direction. In accordance with this, each component of the pilot valve 8, including the solenoids 15a and 15b, is arranged vertically.

With the above configuration, when power to the solenoids 15a and 15b is stopped during scram,
Each movable core 18a, 18b is displaced vertically downward, that is, in the direction of falling. In addition, each movable core 18a, 18b has a structure in which it is only movably supported by cylinders 22a, 22b (shown in FIG. Unlike the so-called horizontal mounting structure mounted above, the sliding contact area during displacement can be made small. As a result, the occurrence of sticks is prevented, the movable cores 18a and 18b are activated immediately and smoothly during scram, and the main valve 17 is opened to ensure that the control rods are inserted into the reactor via the scram valves 9 and 10. Can be inserted in an emergency. Furthermore, as mentioned above, situations that require scrams rarely occur in nuclear power plants, and therefore the movable iron core 18
a and 18b maintain the position where the main valve 17 is closed for a long time (the position displaced in the direction of arrow _X1 in the figure).
Therefore, the movable iron cores 18a, 18b and the cylinder 22
Although there is a possibility that a sticking phenomenon may occur between the movable cores 18a and 22b, as described above, the movable cores 18a and 18b are only supported by the cylinders 22a and 22b to guide their displacement in the vertical direction. Since the sliding contact area is small, the occurrence of sticking phenomenon can be reliably prevented, and thereby the movable cores 18a, 18b can be reliably activated.

Furthermore, considering the vertically installed pilot valve 8 from the aspect of design seismic intensity, the design seismic intensity conditions for nuclear power plants are more strictly specified for the horizontal direction than for the vertical direction. Therefore, in the case of a conventional horizontally mounted pilot valve, it has been difficult to satisfy the design seismic intensity conditions because the movable core is configured to perform horizontal displacement under severe design seismic intensity conditions. However, by vertically mounting the pilot valve 8, the displacement of the movable cores 18a, 18b becomes vertical, which is gentle under the design seismic intensity condition. Thereby, there is no need to make the structure of the pilot valve 8 unnecessarily strong in order to satisfy the design seismic intensity conditions, and the structure of the pilot valve 8 can be simplified and miniaturized.

When wiring a conventional horizontally mounted pilot valve to drive a solenoid,
Because the electrical wiring had to be laid above the front of the hydraulic control unit, the cable duct through which the electrical wiring was inserted had to be bent approximately 90 degrees at the pilot valve position, but it was possible to install the pilot valve 8 vertically. This makes it possible to connect electrical wiring directly from above, eliminates the need to bend the cable duct, and improves the ease of assembling the water pressure control unit 5.

Effects of the Invention As described above, according to the hydraulic control unit of the present invention, the pilot valve is attached to the hydraulic control unit in such a direction that the displacement direction of the movable core during a scram is approximately vertical, so that the movable core during a scram can be moved in the vertical direction. The displacement will be in the falling direction according to gravity, and in addition, the movable core is guided and supported by the cylinder in the pilot valve so that it can be displaced, so the sliding contact area between the movable core and the cylinder is small, and The sticking phenomenon between the movable core and cylinder is reliably prevented, the movable core is displaced immediately and smoothly during a scram, and the main valve is opened smoothly and the control rods are inserted into the reactor via the scram valve. Emergency insertion can be performed reliably, and the direction of displacement of the movable core is perpendicular to the design seismic intensity condition, which eliminates the need to unnecessarily complicate the structure of the pilot valve in order to satisfy the design seismic intensity condition.
It has the advantage of simplifying and downsizing the structure of the pilot valve, thereby improving its earthquake resistance.

[Brief explanation of the drawing]

FIG. 1 is an enlarged front view showing the vicinity of the pilot valve of an embodiment of the water pressure control unit according to the present invention;
Fig. 2 is a front view showing the whole of an embodiment of the water pressure control unit according to the present invention, Fig. 3 is a vertical sectional view of the pilot valve, and Fig. 4 is an enlarged view of the vicinity of the pilot valve of an example of a conventional water pressure control unit. FIG. 5... Water pressure control unit, 8... Pilot valve, 9, 10... Scram valve, 15a, 15b...
... Solenoid, 17... Main valve, 18a, 18b...
...Movable iron core, 22a, 22b...Cylinder.

Claims (1)

[Claims] 1 A water pressure control unit equipped with a double solenoid type pilot valve configured to open a main valve by displacing a pair of movable cores corresponding to the solenoids in a predetermined direction when power is cut off to a pair of solenoids during a scram. In the hydraulic control unit, the double solenoid type pilot valve is mounted in such a direction that the displacement direction of the movable iron core during the scram is substantially vertical.