JPS5913985A - Control rod drive hydraulic device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control rod drive hydraulic system that alleviates the differential pressure between the inflow side and the outflow side of a flow control valve when the pressure inside the reactor is lower than during rated operation. .

[Technical background of the invention]

FIG. 1 shows a control rod drive hydraulic system. In the figure, 1 is a condensate storage tank that serves as a water source, and 2 is a drive water supply pump that draws υ drive water from this tank 1. On the downstream side of the pump 2, it branches into a control rod drive pipe 4 and a scram water filling pipe 6.

A flow control valve 8 is inserted into the control rod drive pipe 4 . 10 in the trench diagram is a directional control valve unit, and this directional control valve unit ytro has a pair of insertion solenoid valves 12 and 12B.
and extraction solenoid valves 141.14B are alternately connected in a ring shape. The four control rod drive pipes are connected via the check valve 15 between the insertion solenoid valve 12A and the withdrawal solenoid valve 14 of the direction control unit 1θ. Solenoid valve 12A for inserting the broken directional control valve Kornit 10
The insertion pipe 16 is connected between the solenoid valve for insertion 12B and the solenoid valve for withdrawal 1.
A drawn-out pipe 18 is connected between 4 and 4. 7. Both the insertion pipe 16 and the withdrawal pipe 18 communicate with the inside of the cylinder 22 of the control rod drive mechanism 20, and the insertion pipe I6 supplies driving water to the lower surface of the piston 24 to raise the piston 24. , the drawing pipe 18 is configured to supply driving water to the upper side of the piston 24 to lower the piston 24. The piston 24 is connected to a control rod 28 in the reactor pressure vessel 26, and is configured to pull out the control rod 28 from the reactor core.

In the figure, reference numeral 30 denotes a cooling water pipe that is branched into multiple branches from the downstream side of the flow control rod 8 of the control rod drive pipe 4, and this linear water pipe 30
is connected to the insertion pipe 16. A pressure regulating valve 32 and a check valve 34 are sequentially inserted into the cooling water pipe 30 from the upstream side. Further, between the insertion solenoid valve 12B and the withdrawal solenoid valve 12 of the directional control valve unit IO, the driving water discharged from the cylinder 22 of the control rod drive mechanism 20 is supplied to the nuclear reactor with coolant. A return pipe 36 for returning into the pressure vessel 26 is connected. A check valve 37 is inserted into the return pipe 36, and the downstream side of the check valve 37 is connected between the pressure regulating valve 32 and the check valve 34 of the cooling water pipe 30 via a branch pipe 38. Another pressure regulating valve 39 is inserted into the branch pipe 38.

On the other hand, the scram water filling pipe 6 is connected to the insertion pipe 16. A georift 40, a check valve 41, and a scram valve 42 are sequentially inserted into this pipe 6 on the upstream side, and are provided in multiple branches between the check valve 4 and the scram valve 42. An accumulator 46 is connected via a branch pipe 44 . This accumulator 46 is filled with scram water used for scram operations, and is also configured to be supplied with high-pressure gas (for example, high-pressure nitrogen gas) for pressurizing the scram water.

Further, a scram outlet valve 50 is connected to the drawn-out pipe 18 via a scram discharge pipe 48.

Next, the operation of the control rod drive hydraulic system constructed as described above will be explained in detail.

First, when inserting control rods during rated reactor operation,
Solenoid valve 121.12B for insertion of directional control valve unit 10
open the valves at the same time. Then, the condensate in the condensate storage tank 1 is drawn out by the drive water supply pump 2, pressurized to a required pressure, and then adjusted to a constant flow rate by the flow control valve 8. In addition, the pressure is adjusted by the pressure 5-regulating valve 32, and the insertion solenoid valve 1
2k and the insertion pipe 16 into the cylinder 22 of the control rod drive mechanism 20, and pressurizes the lower m+ side of the piston 24. This causes the piston 24 to rise, and the control rod 28 connected to the piston 24 to be inserted between the type assemblies loaded in the reactor core. On the other hand, the water on the upper surface side of the piston 24 is discharged through the withdrawal pipe 18, and
and is returned to the reactor pressure vessel 26 via the return pipe 36.

Next, when withdrawing the control rod, the insertion solenoid valves 12A and 12B of the directional control valve unit IO are closed, and at the same time the withdrawal solenoid valve 14. Then, open valve 14B. As a result, the drive water pressurized by the drive water supply pump 2 is supplied to the direction control valve unit lθ through the flow control valve 8 and the control rod drive pipe 4. Then, it flows into the cylinder 22 of the control rod drive mechanism 20 via the drawn pipe 14B and the drawn pipe 18, and pressurizes the upper surface side of the piston 24. As a result, the piston 24 is lowered, and the control rod 28 connected to the piston 24 is pulled out between the type assemblies loaded in the reactor core. On the other hand, water on the lower surface side of the piston 24 is discharged through the insertion pipe 16,
It is returned to the reactor pressure vessel 26 via the extraction solenoid valve 14A and the return pipe 36.

Next, when a system scram signal is generated during reactor shutdown, the scram population valve 42 and the scram outlet valve 5 receive this signal.
0 opens. The top side of the piston 24 is opened to the atmosphere through the scram outlet valve 50, and highly pressurized scram water in the accumulator 46 is supplied to the bottom side of the piston 24 through the scram population valve 42. Ru. Therefore, the piston 24 rises rapidly due to the differential pressure between the upper and lower surfaces, and the control rod 28 is inserted into the reactor core at high speed.

In addition, when the control rod 28 is not inserted, withdrawn, or scrammed, a small amount of low-pressure drive water is used as cooling water through the control rod drive piping 4, the cooling water piping 30, and the insertion piping 16 to control the control rod. A current is passed through the cylinder 22 of the drive mechanism 20 to maintain the function of the control rod drive mechanism 20.

[Problems with background technology]

In order to ensure scram operation in the event of an emergency, the filling water in the Agi Mullet tie 6 is kept at all times.
It is necessary to pressurize it to 120 to 130 kg/-. Therefore, a high pressure required for supplying scram water to the achievement unit 46 acts on the upstream side of the flow rate control valve 8 .

On the other hand, in order to overcome the pressure inside the reactor pressure vessel 26 and insert or withdraw the control rod 28, the reactor pressure vessel 2
20 Kg/or from inside of 6! A fairly high pressure is required, and this pressure is the pressure on the lower IX side of the flow control valve 8. In addition, in order to cause cooling water to flow through the control rod drive mechanism 20, the pressure on the downstream side of the pressure regulating valve 32 is applied to the reactor pressure vessel 26.
It is necessary to keep the internal value of 2Ky/ct/ high.

By the way, the pressure inside the reactor pressure vessel 26 is generally O~
It varies between 70 phrases/crit, and is low when the reactor is shut down (or when the scram is completed) and high during rated operation. Therefore, for example, after the scrum is completed, the accumulator 4
6 When the pressure inside the reactor pressure vessel 26 is low, such as when filling with Hescram water or when the reactor is shut down or started, a temperature of 40 to 110 K is applied between the upstream and downstream sides of the flow control valve 8.
A differential pressure of f/- is generated, and such a high differential pressure may cause erosion in the valve body and valve seat of the flow 1 control valve 8. When such a situation occurs, the flow rate control valve 8 becomes unable to perform control operations, and as a result, the drive pressure for inserting and withdrawing the control rod 28 and the flow rate and pressure of the cooling water for the control rod drive hydraulic device are reduced. There was a risk that it would not be possible to secure it.

[Object of the invention] The present invention was made based on the above circumstances, and
Its purpose is to create a high differential pressure between the upstream and downstream sides of the flow 1 control valve when the pressure in the reactor pressure vessel is low, at the completion of a scram, during reactor shutdown, or during reactor shutdown. This prevents the occurrence of erosion in the valve body and valve seat of the flow control valve, and reduces the drive pressure required for control rod insertion/extraction operations and the flow rate and pressure of cooling water for the control rod drive hydraulic system. The object of the present invention is to provide a control rod-driven hydraulic device that can ensure the following.

[Summary of the invention]

The control rod drive hydraulic device according to the present invention includes a drive water supply pump, a flow control valve that adjusts the flow rate between the pump and the control rod drive unit, and a flow control valve that adjusts the flow rate between the control rod drive unit and the pump. The scram water filling piping is branched from between the scram water filling piping and the pressurized scram water is filled with scram water through this filling piping and is supplied to the control rod drive mechanism via the scram valve to drive the control rods. an akeemulator for high-speed insertion operation; and the flow 1' control valve, which is provided between the branch point leading from the pump to the scram water filling pipe and the flow control valve, and is used when the pressure inside the reactor is lower than during rated operation. A pressure reducing device 10 that relieves the differential pressure between the inflow side and the outflow side of
- A pressure reducing device installed upstream of the flow control valve can reduce the pressure upstream of the flow 1 control valve, thereby reducing the pressure on the upstream side of the flow control valve and This can alleviate the difference H between the downstream side and the downstream side.

[Embodiments of the invention]

FIG. 2 shows one embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

The difference from the control rod drive hydraulic system shown in FIG. 1 is that an orifice 52 as a pressure reducing device is inserted in the control rod drive piping 4. This orifice 52 is provided between the branch point from the driving water supply pump 2 to the scram water filling pipe 6 and the flow I' control valve 8.

With the above configuration, there is an orifice 52 in the control rod drive piping 4 on the upstream side of the (Ilt, iA-control valve 8).
is inserted, a differential pressure is generated between the flow side and the downstream side of the orifice 52, and the upstream pressure of the flow 1 control valve 8 is reduced by that amount.

Therefore, for example, at the completion of a scram, during reactor shutdown, or at reactor startup, the pressure within the reactor pressure vessel 2° decreases,
Along with this, one side of the downstream side of the flow rate control valve 8 decreases, but even in such a case, the upstream side pressure of the flow rate control valve 8 is decreased by the orifice 52, so the pressure on the upstream side of the flow rate control valve 8 and the other side of the flow rate control valve 8 decrease. The differential pressure with the downstream side does not increase at all.

Therefore, the integrity of the flow control valve 8 is maintained even though erosion occurs in the valve body and valve seat of the flow control valve 8. Therefore, the driving pressure required for inserting and withdrawing the control rod 28 and the flow of cooling water for maintaining the control rod drive mechanism 20 are
・It is possible to secure pressure.

Note that the present invention is not limited to the above embodiments.

For example, in the above embodiment, the orifice 52 is used as a pressure reducing device, but the pressure reducing device f! ′ is not limited to orifices.

FIG. 3 shows another embodiment of the present invention, in which a pressure reducing valve 54 is used as the pressure reducing device. In addition, the pressure reducing valve 5
The configurations other than 4 are the same as those in the previous embodiment. Further, the pressure reducing valve 54 changes the throttle 1 according to the differential pressure between the upstream force and the downstream pressure of the flow I control valve 8.
The pressure difference between the upstream side and the downstream side of the control valve 8 may be suppressed.

'') Even with the above configuration, the differential pressure that acts on the flow 1 control valve 8 when the pressure inside the reactor pressure vessel 20 becomes low can be alleviated by the pressure reducing valve 54, so that the flow 1 There is no risk of erosion occurring on the valve body and valve seat of the control valve 8, and the integrity of the flow 1 control valve 8 is maintained. Therefore, the driving pressure of the driving water required for inserting and withdrawing the control rods and the flow rate and pressure of the cooling water flowing through the control rod drive mechanism 20 can be ensured.

〔Effect of the invention〕

As detailed above, the control rod drive hydraulic system according to the present invention @
comprises a drive water supply pump, a directional control valve unit that switches the flow path of drive water from the pump to the control rod drive mechanism to omit insertion or withdrawal of control rods from the core, and this directional control valve unit. 13- A flow rate control valve that performs a flow rate p1 with the pump, a scram water filling pipe branched from between this flow rate control valve and the pump, and a scram water filling pipe provided through the filling pipe. An akeemulator that supplies pressurized scram water filled with water to the control rod drive mechanism via a scram valve and inserts the control rods at high speed; a branch point from the pump to the scram water filling piping; 1 control valve, and a pressure reducing device that relieves the differential pressure between the inflow side and the outflow side of the flow rate control valve when the pressure inside the reactor is lower than during rated operation. If the pressure inside the reactor pressure vessel is low (
This prevents high differential pressure from occurring between the upstream and downstream sides of the flow control valve even at the completion of a scram, during reactor shutdown, during reactor startup, etc. Erosion can be prevented from occurring. Therefore, the integrity of the flow control valve can be maintained, the driving pressure of the driving water required for inserting and withdrawing the control rod, and the pressure of the cooling water flowing through the control rod drive mechanism can be secured, and the control rod Drive-14= The integrity of the mechanism can be maintained and its reliability can be improved.

In addition, since the frequency of replacing the flow 1 control valve is reduced, the radiation exposure of workers and personnel involved in the replacement work is reduced, and the operating rate of the nuclear reactor plant is also improved, providing excellent effects.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a control rod drive water pressure device showing an example of the present invention. Figure 2 is a schematic diagram of a control rod drive water pressure device showing an embodiment of the present invention. FIG. 2 is a schematic configuration diagram showing a part of a control rod drive hydraulic device according to an embodiment of the present invention. 2... Drive water supply pump, 4... Control rod drive piping,
6...Scram water filling pipe, 8...Flow control valve, 1
0... Directional control valve unit, 20... Control rod drive mechanism, 46... Akiko, mulator, 52... Orifice (sweat reduction device), 54... Pressure reducing valve (pressure reducing device). Applicant's agent Patent attorney Takehiko Suzue 15-

Claims (3)

[Claims] (1) A driving water supply pump, a directional control valve unit that switches the flow path of driving water from the pump to the control rod drive mechanism to insert or withdraw the control rods from the core, and this directional control valve unit. A flow rate control valve that adjusts the flow rate between the pump and the pump, a scram water filling pipe branched from between the flow control valve and the pump, and scram water filled through the filling pipe. and an akeemulator that supplies pressurized scram water to the control rod drive mechanism via the scram valve and inserts the control rods at high speed;
Provided between the branch point leading from the pump to the scram water filling piping and the flow control valve, and between the inflow side and the outflow side of the flow control valve when the pressure inside the reactor is lower than during rated operation. A control rod drive hydraulic device characterized by comprising a pressure reducing device that relieves differential pressure. (2) The control rod drive hydraulic device according to item (1) of the special Ff request, characterized in that the pressure reducing device is an orifice. (3) The control rod drive hydraulic device as set forth in claim (1), wherein the pressure reducing device is a pressure reducing valve.