JP2505808B2 - Control rod drive hydraulic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control rod drive water pressure device, and in particular, to a control rod drive mechanism (CRD) for supplying cooling water and control rod insertion / pull-out drive water. In a control rod drive water pressure device equipped with a check ball built-in cooling water check valve in the cooling water supply line to the water pressure control unit to be supplied, vibration and abnormal noise of the check ball are suppressed, and control rod drive speed fluctuations. The present invention relates to a control rod drive water pressure device suitable for preventing the above and appropriately adjusting the distribution of cooling water to each CRD.

[Conventional technology]

FIG. 4 shows an example of the system configuration of a conventional control rod drive water pressure device. In this example, in order to cool the seal portion of the drive piston 8 of the CRD 6 even when the control rod 4 is not driven, the condensate storage tank 54 drives the drive water pump 52, the system flow rate control valve 50, and the pressure control. Valve 46 and balance valve 48, cooling water header 44
From the cooling water supply line 42 to the cooling water check valve 36
Through the cooling water pipe 34 and the insertion pipe 10.
There is a cooling water supply system for.

When the control rod 4 is stopped, the control rod drive water pressure device is in the cooling water supply mode in order to protect the CRD 6. Various seal packings and seal bushes are used inside the CRD6.To prevent these members from deteriorating under the influence of heat from the hot core, cooling water is constantly supplied during operation of the reactor. ing.

In the cooling water supply system, the cooling check valve 36, as shown in FIG. 5, includes a valve body 36A, a check ball 36B, and a valve seat 36C, and is cooled from the cooling water passage 42A on the cooling water pipe 42 side. It has a structure in which cooling water flows to the cooling water flow path 34A side of the water pipe 34.

Vibration or noise may occur in the cooling water check valve 36, resulting in a phenomenon in which the valve closing operation becomes incomplete or uncertain. As described above, the cause of the vibration or noise of the cooling water check valve 36 is that air bubbles remain in the components such as the pipe or the valve of the control rod drive water pressure device, or the components such as in the pipe or the valve. This means that pressure vibrations occur inside and vapor bubbles are generated. Such a phenomenon is caused by the pressure applied from the insertion pipe side to the cooling water pipe side when the control rod is driven, whereby air bubbles and vapor bubbles are compressed and absorbed, and the cooling water check valve is closed. When sufficient pressure is not transmitted and the closing operation becomes uncertain, and when air bubbles and steam bubbles are generated due to the sudden pressure difference between the insertion pipe side and the cooling water pipe side that occurs when the control rod is driven,
Since it rapidly flows into the check ball from the insertion pipe side and passes through to the cooling water pipe side, vibration is applied to the check ball,
The closing operation may be uncertain.

As a method of preventing the unstable operation of the cooling water check valve and ensuring the drive of the control rod, for example, as shown in Japanese Patent Laid-Open No. 61-144593, instead of the cooling water check valve, cooling water is used. A method is known in which a remote control valve is provided in the middle of piping and the remote control valve is closed during control drive. This method requires a remote control valve that opens and closes when an electric signal is input and an electric control system, which complicates the equipment.

Note that Japanese Patent Application No. 60-104287 and the like have been proposed for the purpose of preventing abnormal insertion and withdrawal of the control rod due to defective operation of the water pressure control unit inward control valve. In addition, Japanese Patent Application No. 58-173 was used for the purpose of adjusting the flow rate of cooling water to the CRD.
There is No. 065.

[Problems to be Solved by the Invention]

The above-mentioned conventional technology uses a method using a remote control valve, that is, an electrical method, as a solution, in order to prevent vibration and abnormal noise of the cooling water check valve in the water pressure control unit of the CRD, and control rod drive speed fluctuations. There is a risk that new electrical troubles such as erroneous signals will occur without avoiding complication. In order to reduce the cause of this trouble, it is necessary to provide a double guarantee circuit and the like, and there is a problem that the facility system becomes more and more complicated.

On the other hand, in Japanese Utility Model No. 60-185299, depending on the diameter of the check ball 36B, the seatability on the valve seat 36C may deteriorate.
The relationship between the diameter D of the check ball 36B and the hole diameter D1 of the valve seat 36C is regulated within a predetermined range as the cause of vibration and noise of the cooling water check valve in the water pressure control unit of the RD and fluctuation of the control rod drive speed. A check valve for cooling water is proposed.

According to our recent knowledge, the seatability of the check ball 36B when the check valve is suddenly loaded with reverse pressure cannot be improved only by the regulation of the relationship of D1 and D2.
It was found that the relationship between the diameter D2 of 36B and the inner diameter D of the ball storage portion of the valve body 36A is important. When the counter pressure is applied, the check ball 36B swings in the counter pressure flow. At that time, if the gap D-D2 between the check ball 36B and the valve body 36A is large, the swing amount of the check ball 36B is increased accordingly, and the misalignment with the seating hole of the valve seat 36C and the back pressure flow toward the cooling water side occur. The amount of leakage of the
The seatability of the check ball 36B on the valve seat 36C deteriorated, and the control rod drive speed fluctuated.

In order to improve the seatability of the check ball, the gap D-D2 is provided within a range that does not hinder the movement of the check ball when opening and closing.
It is inferred that it is important to make the pressure as small as possible to prevent leakage of back pressure flow to the cooling water side and swing of the check balls. By doing so, it is considered that the problem of seating property can be solved without being restricted by the range of D2 / D1 regulated by Jitsukai Sho 60-185299.

It is an object of the present invention to utilize the advantage that the cooling water check valve of the prior art does not require electrical control, while vibrating or abnormal noise of the cooling water check valve in the control rod drive water pressure device and controlling rod drive speed fluctuation. The present invention is to provide a control rod drive water pressure device that can prevent the above and also appropriately distribute the cooling water to the CRD.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention provides a check ball built-in type cooling system in a cooling water supply line to a water pressure control unit that supplies cooling water to a control rod drive mechanism and control rod insertion / withdrawal drive. In a control rod drive water pressure device equipped with a water check valve, a check ball built-in type cooling water check valve vibrates a check ball including a vibration absorbing cage that has a hole on the side that communicates with the supply line and stores the check ball. The present invention proposes a control rod drive hydraulic device equipped with an absorption mechanism.

It is desirable to form a plurality of communication holes on the side surface of the vibration absorbing cage and symmetrically with respect to the vibration absorbing cage.

The vibration absorbing mechanism may be composed of a vibration absorbing cage that houses the check ball and a vibration absorbing body that is arranged between the check valve body and the vibration absorbing cage.

The vibration absorbing mechanism may include a cooling water supply flow rate adjusting orifice on the cooling water inflow side end surface of the vibration absorbing cage.

[Action]

In the present invention, since the cooling water check valve with a built-in check ball is provided with the vibration absorbing mechanism of the check ball including the vibration absorbing cage having the hole communicating with the supply line on the side surface and storing the check ball. Even if vibration and abnormal noise occur, it is immediately suppressed, and CRD speed fluctuations are prevented.

If a plurality of communication holes, that is, cooling water outlet flow paths are formed on the side surface of the vibration absorbing cage in axial symmetry of the vibration absorbing cage,
When the cooling water flows, the deviation and fluctuation of the check ball in the radial direction from the axis of the vibration absorbing cage are reduced, and the fluctuation of the CRD speed is prevented. That is, by providing a plurality of cooling water outlet channels on the side surface of the vibration absorbing cage and changing the size, shape, number, position, etc. of the cooling water outlet channels, the required flow rate of cooling water is secured. , It is possible to reduce the direct transmission of the water hammer wave to the cooling water side when the back pressure is suddenly applied.

The flow rate adjusting orifice of the present invention is installed for the purpose of adjusting the flow rate of cooling water to each CRD. In a large nuclear power plant, for example, 185 CRDs are installed in a nuclear reactor, and the temperature environment varies depending on the arrangement position in the nuclear reactor. As described above, it was not possible to supply an appropriate amount of cooling water to each of the CRDs having different temperature conditions in the above-mentioned No. 60-185299, which has no cooling water flow rate adjusting mechanism.

When the orifice is provided in the cooling water check valve according to the present invention, the orifice which has been conventionally in the CRD can be eliminated, and the temperature rise due to the clogging of the orifice in the CRD can be prevented. With the conventional structure, if the orifice in the CRD was clogged during reactor operation, disassembly and adjustment were impossible, but
The water pressure control unit can be disassembled and adjusted by closing the isolation valve when necessary and isolating the system, and even if an abnormality occurs in the orifice in the cooling water check valve, it can be easily inspected and adjusted.

Moreover, in this structure, since electricity is not used, reliability is not deteriorated even if a multiplex guarantee circuit or the like is not provided. Therefore, the cost is almost the same as the conventional one, and it can be back-fitted to the conventional system.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a diagram showing a system configuration of an embodiment of a control rod drive hydraulic device according to the present invention.

In FIG. 1, 2 is a reactor pressure vessel, 4 is a control rod to be inserted into or extracted from the reactor core, 6 is a drive piston 8
CRD for driving the control rod 4, 10 is an insertion pipe for supplying pressure water to the CRD 6 at the time of insertion, 12 is a drawing pipe for supplying pressure water to the upper side of the drive piston 8 when the control rod is withdrawn, 14 is a water pressure control unit, 16 is a normal drive switching valve having four valves 18 to 24 for switching between insertion and withdrawal of a control rod, 26
Is a scrum outlet valve for discharging water on the extraction side during reactor scram, 28 is a drain header for discharged water, 30 is a scrum inlet valve for emergency insertion of control rod during scram, and 32 is high pressure water. An accumulator to be supplied, 34 is a cooling water pipe for supplying cooling water to the seal portion of the CRD even when the control rod is stopped, 37 is a cooling water check valve according to the present invention, and 38 is a vibration absorbing mechanism check. A valve, 40 is an orifice as a cooling water flow rate adjusting mechanism, 42 is a cooling water supply line, 44 is a cooling water header, 46 is a pressure control valve, 48 is a balance valve in parallel with the pressure control valve 46, and 50 is a system flow rate control valve. , 52 is a driving water pump, 54 is a condensate storage tank, 56 is a filling water line, 58 is a filling water header, 60 is a driving water supply line, 62 is a driving water supply header, 64 is a discharging water line, and 66 is discharging water. It is a header.

The feature of this embodiment is that a cooling water check valve 37 including a vibration absorbing check valve 38 and an orifice 40 for adjusting the cooling water flow rate is provided in place of the cooling water check valve 36 of FIG. It is a point.

FIG. 2 is a sectional view showing a check valve 38 with a vibration absorbing mechanism, which has an orifice 40 built therein.

The check valve 38 with the vibration absorbing mechanism of the present embodiment is provided with the valve body 38A.
And a check ball 38B, a vibration absorbing cage 38D, and a vibration absorber 38E. The vibration absorbing cage 38D is provided at its lower end with an orifice 40 as a cooling water flow rate adjusting mechanism. The vibration absorber 38E is made of a rubber-based material or a resin-based material as in the present embodiment and has its own absorbing ability, and is constructed in the shape of a flat spring to absorb vibrations as shown in FIG. There are cases.

The system flow rate adjusting valve 50 is automatically controlled in accordance with the steady set flow rate so that the cooling water flow rate having the water pressure necessary to protect the seal parts of all CRDs can be supplied, and the cooling water supply line 42 CR via the water pressure control unit 14 and the insertion pipe 10.
Supply cooling water to D6. The pressure control valve 46 adjusts to drive water having a water pressure necessary for the normal drive operation of the CRD 6 for inserting or withdrawing the control rod 4, and any valve in the balance valve 48 is opened or closed to open the control rod 4. A stable flow rate of driving water at the time of insertion or withdrawal is supplied to the CRD 6 through the driving water supply line 60, the water pressure control unit 14, the insertion pipe 10 or the withdrawal pipe 12.

Next, the operation of moving the control rod in and out by the control rod drive water pressure device according to the present invention having such a configuration will be described.

When the control rod 4 in the reactor pressure vessel 2 is inserted, that is, moved upward, the high-pressure water boosted by the drive water pump 52 passes through the system flow control valve 50 and is driven by the pressure control valve 46 to drive it. Adjusted to water pressure. The withdrawal side of the flow balance valve 48 is closed, and the flow rate required to drive the insertion of one CRD is passed through the drive water supply header 62 and then the normal drive switching valve in the water pressure control unit 14.
Is supplied to the lower chamber of the drive piston 8 of the CRD 6 via 18.
Push up the drive piston 8. On the other hand, the water in the upper chamber of the drive piston 8 is discharged by the drawing pipe 12 connected to the CRD 6.
It flows out to the discharge water header 66 through the normal drive switching valve 24 in the water pressure control unit 14.

When pulling out the control rod 4 from the core, that is, moving it downward, the high-pressure water pressurized by the driving water pump 52 passes through the system flow rate adjusting valve 50 and is driven by the pressure adjusting valve 46, as in the insertion mode described above. It is adjusted to the water pressure required for. This time, the insertion side of the flow balance valve 48 is closed, and the flow rate necessary for pulling out drive of one control rod drive device passes through the drive water supply header 62, the normal drive switching valve 20 in the water pressure control unit 14, and the CRD. Is supplied to the upper chamber of the drive piston 8 and pushes down the drive piston 8. The water in the lower chamber of the drive piston 8 flows out from the insertion pipe 10 connected to the CRD 6 to the discharge water header 66 via the normal drive switching valve 22 in the water pressure control unit 14.

Further, when an abnormality occurs in the reactor plant and it is necessary to stop the reactor urgently, a signal from the reactor protection system is received, and the scrum inlet valve 30 in the water pressure control unit 14 automatically opens, High-pressure water filled in the accumulator 32
It is supplied to the lower chamber of the drive piston 8 in the CRD 6 through the insertion pipe 10 and rapidly inserts all the control rods 4 into the core. At this time, since the scrum outlet valve 26 in the water pressure control unit 14 is automatically opened at the same time as the scrum inlet valve 30, the water in the upper chamber of the drive piston 8 in the CRD 6 is pulled out.
12, It flows out to the scrum discharge header 28 through the scrum outlet valve 26, and the scrum operation can be surely achieved.

Explaining the cooling water supply passage, the driving water pump 52
The high-pressure water that has been increased in pressure is adjusted by the system flow control valve 50 to a cooling water pressure that always maintains a constant differential pressure with respect to the cooling water supply flow rate required for all control rod drives and the furnace pressure, and passes through the cooling water header 44. , Through each water pressure control unit 14 and the insertion pipe 10, flows into the lower chamber of the drive piston 8 of each CRD 6, passes through the cooling water port, the cooling water orifice, and the seal portion, and flows out into the reactor. In addition, at the time of other than scrum, that is, during the normal drive operation, the CRD is selected and operated one by one,
The CRDs that are not operated are stopped in place and are all in cooling mode.

In the control rod drive water pressure device of the present embodiment, in any case of the control rod insertion and withdrawal and the emergency stop operation when the reactor is abnormal, the same operation as in the prior art can be performed, and the control rod stopped cooling water supply can be performed. There is no change in the mode.

As shown in FIG. 5, the conventional cooling water check valve has a valve seat 36C formed on a valve body 36A, and the valve body 36A is welded to the cooling water pipe 34. Although it was very difficult to replace with a spare part, in the present invention, since the valve seat is formed in the vibration absorbing cage 38D, this part can be easily disassembled and inspected and replaced with a spare part.

Further, since an orifice as a cooling water flow rate adjusting mechanism is formed in the lower part thereof, the flow rate to each CRD 6 can be finely adjusted.

〔The invention's effect〕

According to the present invention, the cooling water check valve is provided with the vibration absorbing mechanism including the vibration absorbing cage, restricts the movement of the check balls in the radial direction of the flow path, that is, the vibration, and suppresses the back pressure water to the cooling water side. Since there is less leakage and the seatability of the ball can be improved, there is no vibration or abnormal noise of the check ball, and CR
D speed fluctuation is prevented.

Further, when the cooling water check valve is provided with an orifice, it is possible to eliminate the orifice which has conventionally been in the CRD and prevent the temperature rise due to the clogging of the orifice in the CRD. Even if the orifice of the cooling water check valve is clogged, it is easy to isolate the water pressure control unit and disassemble and adjust it.

A plurality of cooling water outlet channels are provided on the side surface of the vibration absorbing cage. By changing the size, shape, number, position, etc. of this cooling water outlet channel, the water hammer wave when a reverse pressure is suddenly applied is directly applied to the cooling water side while securing the required flow rate of the cooling water. You can ease the transmission.

Furthermore, since electricity is not used to drive the cooling water check valve,
The reliability does not decrease even if the multiple guarantee circuit is not provided.
Therefore, the cost is almost the same as that of the conventional system, and the system can be back-fitted to the conventional system.

[Brief description of drawings]

1 is a diagram showing a system configuration of an embodiment of a control rod water pressure device according to the present invention, and FIG. 2 is a longitudinal sectional view showing a configuration of an example of a cooling water check valve used in the embodiment of FIG. FIG. 3 is a longitudinal sectional view showing another embodiment of the cooling water check valve, FIG. 4 is a view showing an example of a system configuration of a conventional control rod drive water pressure device, and FIG. 5 is a conventional example of FIG. It is a figure which shows an example of the cooling water check valve used. 6 …… CRD, 8 …… Drive piston, 10 …… Insertion pipe, 12
...... Pulling out piping, 14 …… Water pressure control unit, 34 …… Cooling water piping, 37 …… Cooling water check valve, 38 …… Check valve with vibration absorbing mechanism, 38A …… Valve body, 38B …… Check ball , 38D ...
… Vibration absorber cage, 38E …… Vibration absorber, 40 …… Cooling water flow rate adjusting mechanism (orifice), 42 …… Cooling water supply line, 44 …… Cooling water header.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Noriaki Mase 3-1-1 Sachimachi, Hitachi, Ltd. Inside the Hitachi factory, Hitachi Co., Ltd. (56) References Kai 57-98370 (JP, U)

Claims (4)

(57) [Claims] 1. A check water built-in cooling water check valve is provided in a cooling water supply line to a water pressure control unit that supplies cooling water for cooling and control rod insertion / withdrawal driving to a control rod drive mechanism. In the control rod drive water pressure device, the check water built-in type cooling water check valve includes a vibration absorbing mechanism of a check ball including a vibration absorbing cage having a hole communicating with the supply line on a side surface and storing the check ball. A control rod drive hydraulic device characterized in that 2. The control rod drive hydraulic device according to claim 1, wherein a plurality of the communication holes are formed on a side surface of the vibration absorbing cage. 3. The vibration absorbing mechanism according to claim 1 or 2, wherein the vibration absorbing mechanism is arranged between the vibration absorbing cage storing the check ball and the check valve body and the vibration absorbing cage. A control rod drive water pressure device comprising: 4. The vibration absorbing mechanism according to any one of claims 1 to 3, wherein the vibration absorbing mechanism includes a cooling water supply flow rate adjusting orifice at an end surface of the vibration absorbing cage on the cooling water inflow side. A control rod drive hydraulic device characterized in that