JPS63309891A - Hydraulic device for driving control rod - Google Patents

Abstract

PURPOSE:To prevent the vibration of a cooling water check valve and the fluctuation in the speed of a control rod driving mechanism by providing a check valve with a vibration absorbing mechanism and orifice for adjusting the flow rate of cooling water to the cooling water check valve. CONSTITUTION:The check valve 38 with the vibration absorbing mechanism consists of a valve body 38A, a check ball 38B, a vibration absorbing gage 38D, and a vibration absorbing body 38E and is provided with the orifice 40 as a mechanism for controlling the flow rate of the cooling water at the bottom end of the gage 38D. Since the vibration absorbing mechanism of the check ball 38B is provided to the check valve 38 in such a manner, the vibration and abnormal noise of the check ball 38B are immediately controlled even if said vibration and noise are generated. In addition, the fluctuation in the speed of the control rod driving mechanism is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control rod drive hydraulic device, and in particular, a control rod drive mechanism (hereinafter referred to as CRD) with cooling water and control rod insertion/extraction drive. In a control rod drive hydraulic system that is equipped with a cooling water check valve with a built-in check ball in the cooling water supply line to the hydraulic control unit that supplies drive water to the control rod drive speed, vibration and abnormal noise of the check ball are suppressed. The present invention relates to a control rod drive hydraulic system suitable for preventing fluctuations in the flow rate and appropriately adjusting the distribution of cooling water to each CRD.

[Conventional technology]

An example of the system configuration of a conventional control rod drive hydraulic system is shown in FIG. In this example, in order to cool the seal portion of the driving piston 8 of the CRD 6 even when the control rod 4 is not being driven, the driving water pump 52. System flow rate adjustment valve 50. Pressure regulating valve 46 and balance valve 48. A cooling water supply system is provided from the cooling water ladder 44 to the CHD 6 through the cooling water check valve 36 provided in the middle of the cooling water supply line 42 and through the cooling water piping 34 and the insertion piping 10.

When the control rod 4 is stopped, the control rod drive hydraulic system is in a cooling water supply mode to protect the CHD 6. Various seal backings and seal bushings are used inside CHD6, and cooling water is constantly supplied during reactor operation to prevent these components from deteriorating due to the effects of heat from the high-temperature reactor core. .

In the cooling water supply system, the cooling check valve 36 has a valve body 36A and a check ball 36B, as shown in FIG.
and a valve seat 36G, and has a structure in which cooling water flows from the cooling water passage 42A on the cooling water piping 42 side to the cooling water passage 34A side of the cooling water piping 34.

Vibration and abnormal noise may occur in the cooling water check valve 36, which may cause the valve to close incompletely or unreliably. As described above, vibrations and abnormal noises may occur in the cooling water check valve 36 due to air bubbles remaining in the piping or components such as valves of the control rod drive hydraulic system, or due to air bubbles remaining in the piping or components such as valves. This is the case when pressure oscillations occur inside the tank and steam bubbles are generated. In this case, when the control rods are driven, air bubbles and steam bubbles are compressed and absorbed by the pressure applied from the insertion piping side to the cooling water piping side, and the cooling water check valve does not have enough pressure to close. If the pressure is not transmitted, making the closing operation uncertain, or if air bubbles and steam bubbles are generated when the control rod is driven, the cooling water piping may be disconnected from the insertion piping side due to a sudden pressure difference between the insertion piping side and the cooling water piping side. Since it rapidly flows into and passes through the check ball portion to the side, it may cause vibration to the check ball and make the opening movement difference uncertain.

As a method to prevent the unstable operation of the cooling water check valve and ensure the drive of the control rod, for example, as shown in Japanese Patent Application Laid-Open No. 144593/1983, a cooling water piping system is used instead of the cooling water check valve. A method is known in which a remote control valve is provided in the middle and the remote control valve is closed during control driving. This method requires a remote control valve that opens and closes by inputting an electrical signal and a control electrical system, which complicates the equipment.

Note that Japanese Patent Application No. 104287/1987 is aimed at preventing abnormal insertion and withdrawal of control rods due to malfunction of the internal directional control valve of the water pressure control unit. Furthermore, there is a system for adjusting the flow rate of cooling water to the CRD, such as Japanese Patent Application No. 173065/1983.

[Problem that the invention seeks to solve]

The above conventional technology uses a method using a remote control valve, that is, an electrical method, in order to prevent vibrations and abnormal noises of the cooling water check valve in the CRD water pressure control unit, as well as control rod drive speed fluctuations. Complications are inevitable, and new electrical troubles such as erroneous signals may occur. In order to reduce this trouble factor, it is necessary to provide a double guarantee circuit, etc., which causes the problem that the equipment system becomes increasingly complex.

It is an object of the present invention to take advantage of the advantage that the conventional cooling water check valve does not require electrical control, and to solve the problem of vibrations and abnormal noises of the cooling water check valve in a control rod drive hydraulic system and control rod drive speed fluctuations. It is an object of the present invention to provide a control rod drive hydraulic device that can prevent this and also appropriately distribute cooling water to the CHD.

[Means for solving problems]

In order to achieve the above object, the present invention provides a cooling water check valve with a built-in check ball in the cooling water supply line to the water pressure control unit that supplies cooling water to the CHD and driving water for driving control rod insertion and withdrawal. This paper proposes a control rod drive hydraulic system equipped with a check ball vibration absorption mechanism in a check ball built-in cooling water check valve.

The vibration absorbing mechanism includes a vibration absorbing cage that accommodates a check ball, and a vibration absorbing body disposed between the check valve body and the cage.

This vibration absorption mechanism may include a cooling water supply flow rate adjustment orifice on the cooling water inflow side end face of the vibration absorption cage.

(Function) In the present invention, since the check ball built-in cooling water check valve is equipped with a check ball vibration absorption mechanism, even if check ball vibration and abnormal noise occur, they are immediately suppressed, and C
RD speed fluctuations are prevented.

In addition, if an orifice is provided in the cooling water check valve, conventionally,
The orifice in the CRD can be removed, and temperature rises due to clogging of the orifice in the CRD can be prevented. With the conventional structure, if the hydraulic rift in the CRD becomes clogged during reactor operation, it is impossible to disassemble and make any adjustments. It can be disassembled and adjusted, and even if an abnormality occurs in the orifice inside the cooling water check valve, it can be easily inspected and adjusted.

Furthermore, since this structure does not use electricity, reliability does not decrease even if a multiple guarantee circuit or the like is not provided.

Therefore, the cost is almost the same as that of the conventional system, and it is possible to backfit the system to the conventional system.

〔Example〕

Next, embodiments of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a system diagram showing an example of the system configuration of a control rod drive hydraulic device according to the present invention. In the figure, 2 is a reactor pressure vessel, 4 is a control rod that is inserted into or withdrawn from the reactor core, and 6 is a control rod that is inserted into or withdrawn from the reactor core.
is a CRD that drives the control rod 4 by a drive piston 8;
, 10 is an insertion pipe that supplies pressurized water when inserted into the CHD 6, 12 is a withdrawal pipe that supplies pressurized water to the upper side of the drive piston 8 when withdrawing the control rod, 14 is a water pressure control unit, and 16 is a control A normally operated switching valve having four valves 18 to 24 for switching between insertion and withdrawal of rods; 26 is a scram exit valve for discharging water on the extraction side during reactor scram;
28 is a discharge header for discharged water, 30 is a scram valve for emergency insertion of a control rod during a scram, 32 is an accumulator that supplies the high-pressure water, and 34 is a CHD control valve even when the control rods are stopped, as described above. 37 is a cooling water check valve according to the present invention, 38 is a check valve with a vibration absorption mechanism, 40 is an orifice as a cooling water flow rate adjustment mechanism, and 42 is a cooling water pipe that supplies cooling water to the seal portion. Supply line, 44 is a cooling water header, 46 is a pressure control valve, 48
50 is a system flow rate regulating valve; 52 is a drive water pump; 54 is a condensate storage tank;
58 is a filling water line, 60 is a driving water supply line, 62 is a driving water supply header, 64 is a discharge water line, and 66 is a discharge water header.

The feature of the present invention is that in place of the cooling water check valve 36 in FIG.
It is equipped with a cooling water check valve 37 consisting of a check valve 38 with a vibration absorption mechanism and an orifice 40 for adjusting the flow rate of cooling water.

FIG. 2 is a sectional view showing a check valve 38 with a vibration absorbing mechanism incorporating an orifice 40. As shown in FIG.

The check valve 38 with a vibration absorption mechanism of the present invention has a valve body 38A.
, a check ball 38B, a vibration absorbing cage 38D, and a vibration absorber 38E.

The vibration absorbing cage 38D is provided with an orifice 40 at its lower end as a cooling water flow rate adjustment mechanism.

The vibration absorber 38E may be made of a rubber-based material or a resin-based material as in this example, and may have absorption capacity itself;
As shown in FIG. 3, it is sometimes configured in the shape of a bell spring to absorb vibrations.

The system flow rate adjustment valve 50 is automatically controlled in accordance with the steady set flow rate so as to supply a flow rate of cooling water with the water pressure necessary to protect the seal portions of all CRDs, and ．． Water pressure control unit 14. Insertion piping 1
0 and is supplied to CHD6. The pressure regulating valve 46 adjusts the driving water to have the water pressure necessary for the normal driving operation of the CHD 6 for inserting or withdrawing the control rod 4, and opens or closes any valve in the balance valve 48 to control the control rod 4. The driving water supply line 60 and water pressure control unit 14 maintain a stable driving water flow rate during insertion or withdrawal. It is supplied to the CHD 6 via the insertion pipe 1o or the withdrawal pipe 12.

Next, the operation of moving the control rod in and out using the apparatus of the present invention having such a configuration will be described.

When inserting (moving upward) the control rod 4 in the reactor pressure vessel 2, the high-pressure water boosted by the drive water pump 52 passes through the system flow rate adjustment valve 5o and is driven by the pressure control valve 46. Adjust to the required driving water pressure10). The withdrawal side of the flow rate balance valve 48 is closed, and the flow rate necessary for driving the insertion of one CRD is supplied to the driving water via the ladder 62.
Via the normally operated switching valve 18 in the water pressure control unit 1.4,
It is supplied to the lower chamber of the driving piston 8 of the CRD 6 and pushes up the driving piston 4.

On the other hand, the water in the upper chamber of the drive piston 4 flows out to the discharge water header 66 via the continuous drive switching valve 24 in the water pressure control unit 14 through the withdrawal pipe 12 connected to the CRD 6.

When withdrawing the control rods 4 from the core (moving them downward), the high-pressure water boosted by the driving water pump 52 passes through the system flow rate adjustment valve 50 and is driven by the pressure adjustment valve 46 in the same way as in the insertion mode described above. The water pressure is adjusted to the required level. This time, the insertion side of the flow rate balance valve 48 is closed, and the flow rate necessary for the withdrawal drive of one control rod drive device is supplied to the drive water via the ladder 62, the constant drive switching valve 20 in the water pressure control unit 14, and the flow rate to the CRD. It is supplied to the upper chamber of the drive piston 8 and pushes the drive piston 8 down. The water in the lower chamber of the driving piston flows out of the insertion pipe 10 connected to the CRD 6 to the exhaust water header 66 via the constant drive switching valve 33 in the water pressure control unit 14.

In addition, if an abnormality occurs in the reactor plant and it is necessary to stop the reactor urgently, the scram inlet valve in the water pressure control unit 14 receives a signal from the reactor protection system.
0 automatically opens, and the high-pressure water filled in the accumulator 32 passes through the insertion pipe 10 and reaches the drive piston 8 in the CRDG.
is supplied to the lower chamber of the reactor, and all control rods 4 are rapidly inserted into the reactor core.

At this time, since the scram exit valve 26 in the water pressure control unit 14 is also automatically opened at the same time as the scram inlet valve 30, the water in the upper chamber of the drive piston 8 in the CRDG is removed from the extraction pipe 12. It flows out through the scram outlet valve 26 to the scram discharge header 28 to ensure that scram operation can be achieved.

To explain the cooling water supply flow path, the drive water pump 52
The high-pressure water boosted at
The water flows through the water pressure control unit 14 and the insertion pipe 10 into the lower chamber of the drive piston 8 of each CRD 6, passes through the cooling water 2-t, the cooling water orifice and the seal, and flows out into the reactor. . It should be noted that the CRDs that are constantly operated except during scram are selectively operated one by one, and the CRDs that are not operated are stopped at a predetermined position and are all in cooling mode.

As described above, in the control rod drive hydraulic system according to the present invention, both the insertion and withdrawal of control rods and the emergency shutdown operation in the event of a reactor abnormality can be performed in exactly the same manner as in the prior art, and the control rods are in a stopped state. There is no difference at all in the cooling water supply mode.

As shown in FIG. 5, the conventional cooling water check valve has a valve seat 36C formed on a valve body 36A.
Since the valve body 36A is welded to the cooling water pipe 34, it has been very difficult to disassemble and inspect it and replace it with spare parts.However, in the present invention, the valve seat is attached to the vibration absorbing cage 38.
Since it is formed in the shape of D, it is easy to disassemble and inspect this part and replace it with spare parts. Also, since the orifice is formed in the lower part as a cooling water flow rate adjustment mechanism, each C
The flow rate to RD6 can be finely adjusted.

〔Effect of the invention〕

According to the present invention, since the cooling water check valve is equipped with a vibration absorption mechanism, there is no vibration of the check ball and generation of abnormal noise, and speed fluctuations of the CRD are prevented.

Further, when the cooling water check valve is provided with an orifice, the orifice that was conventionally located inside the CRD can be removed, and a temperature rise due to clogging of the orifice inside the CRD can be prevented.

Even if this orifice should become clogged, it is easy to isolate the water pressure control unit and disassemble it for adjustment.

Furthermore, since electricity is not used to drive the cooling water check valve, reliability does not deteriorate even if a multiple guarantee circuit is not installed. Therefore, the cost is almost the same as that of the conventional system, and it can be backfitted to the conventional system.

[Brief explanation of the drawing]

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

Claims (1)

[Claims] 1. A cooling water check valve with a built-in check ball in the cooling water supply line to the water pressure control unit that supplies cooling water to the control rod drive mechanism and drive water for driving control rod insertion and withdrawal. A control rod drive hydraulic system comprising: the check ball built-in cooling water check valve comprising a check ball vibration absorption mechanism. 2. Claim 1 provides that the vibration absorption mechanism includes: a vibration absorption cage that accommodates the check ball; and a vibration absorption body disposed between the check valve body and the cage. Features a control rod-driven hydraulic system. 3. The control rod drive according to claim 1 or 2, wherein the vibration absorption mechanism includes a cooling water supply flow rate adjustment orifice on the cooling water inflow side end surface of the vibration absorption cage. Water pressure equipment.