JPS60205395A - Driving hydraulic device for control rod - 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 [Technical Field of the Invention] The present invention relates to a control rod drive hydraulic system for a boiling water nuclear reactor.

[Technical Background of the Invention] Generally, a boiling water nuclear reactor is provided with a control rod drive mechanism driven by water pressure, and the control rod drive mechanism inserts or withdraws the control rods from the reactor core. The control rod drive mechanism is supplied with drive water and cooling water from the control rod drive hydraulic system, and waste water discharged from the control rod drive mechanism is returned to the control rod drive hydraulic system.

The control rod drive hydraulic system is constructed as shown in FIG. In other words, 1 in the figure shows only a part of the bottom of the reactor pressure vessel, which has a closed structure.
A control rod drive mechanism housing 2a is provided in the control rod drive mechanism housing 2a, and the control rod drive mechanism 2 is incorporated inside this housing. Although a large number of control rod drive mechanisms 2 and control rod drive housings 2a are provided in a 1M nuclear reactor, only one of them is illustrated.

Each control rod drive mechanism housing 2a has an insertion pipe 3
A water pressure control unit 5 is connected via a drawn piping 4. Driving water is sent from this water pressure control unit 5 to the control rod drive mechanism 2, and each control rod drive mechanism 2
The drained water is returned to the water pressure control unit 5.

Each hydraulic control unit 5 is provided one unit 1 for each control rod drive mechanism 2, and the total hydraulic control unit 5 constitutes a control rod drive hydraulic device.

Pressure water is distributed and supplied to each of the water pressure control units 5 from a drive water supply unit 6 provided for each nuclear reactor. This drive water supply section 6 is provided with a pump 7, which pressurizes condensate supplied from a condensate storage tank 7a installed outside the reactor building. The high-pressure water discharged from the pump 7 passes through the flow rate adjustment valve 8 and is supplied to each water pressure control unit 5 as driving water via the driving water header 9a and the driving water piping 9. Further, the high pressure water discharged from the pump 7 passes through a pressure regulating valve 10 and is reduced in pressure to a predetermined pressure, and then is supplied as cooling water to each water pressure control unit 5 via a cooling water header 11a and a cooling water pipe 11. Furthermore, a stabilizing valve 12.13 is connected in parallel with the pressure regulating valve 10.
A portion of the drive water passes through these stabilizing valves 12, 13, bypasses the pressure regulating valve 10, and is supplied as cooling water to each hydraulic control unit 1-5. and tlI
When driving the IIll rod, when the flow rate of driving water supplied to the hydraulic control unit 5 increases, these stabilizing valves 12゜1
3 is closed and the flow rate sent as cooling water is reduced to compensate for the increase in the flow rate of driving water, so that the required flow rate as driving water is always ensured. On the other hand, wastewater discharged from the control rod drive mechanism 2 when driving the control rods passes through the water pressure control unit 5 and is returned to the drive water supply section 6 via the drainage pipe 14 and the drainage header 14a. The returned wastewater is then sent as cooling water through the cooling water header 118 to another water pressure unit (not shown).

Further, a directional control valve mechanism 15 including four directional control valves 15a, 15b, 15c, and 15d is provided in the water pressure control unit 5, and the upper l! [! The driving water piping 9, the cooling water piping 11, and the drainage piping 14 all have this directional control valve mechanism 15, and each isolation valve 3a,
It is connected to the insertion pipe 3 and the withdrawal pipe 4 via 4a.

The directional control valves 15a, 15b, 15c, and 15d are all closed when the control rod drive mechanism 2 is not driven. The cooling water sent through the cooling water pipe 11 is supplied to the insertion side of the control rod drive mechanism 2 through the insertion pipe 3. This cooling water passes through an orifice (not shown) provided in the IIIllIiM motive net 2.
It rises between the rod drive mechanism 2 and the control rod drive mechanism housing 2a, cools the control rod drive mechanism 2, and then flows into the reactor pressure vessel 1.

In addition, when inserting the ffIIwJ rod, the direction control valve 15
b, 15c is opened, and driving water is supplied to the insertion side of the control rod drive mechanism 2 through the direction INHI valve 15c and the insertion pipe 3. At this time, the wastewater discharged from the withdrawal side of the control rod drive mechanism 2 is discharged from the withdrawal pipe 4, the direction control valve 15b, and the drainage arrangement i! 14 and is returned to the driving water supply section 6.

Also, when pulling out the control rod, the direction control valve 15a.

Open the valve 15d and let the driving water pass through the direction control valve 15d and the extraction pipe 4. 1111 Supplied to the extraction side of the rod drive mechanism 2. At this time, the wastewater discharged from the insertion side of the rod drive mechanism 2 is transferred to the insertion pipe 3 and the direction control valve 1.
5a and the discharge water pipe 14 to the driving water supply section 6.
be returned to.

Furthermore, the hydraulic control unit 5 is provided with an accumulator 16 for scram insertion of a control rod.

A sufficient amount of scram water is stored in this accumulator 16 to cause the control rod drive mechanism 2 to perform a scram operation, and this scram water is constantly pressurized by high-pressure nitrogen in a nitrogen container 17.

The accumulator 16 is connected to the insertion pipe 3 via a scram inlet valve 18.

Further, a scram discharge header 19 is connected to the drawn pipe 4 via a scram outlet valve 20. For example, a pair of scram discharge headers 19 are provided, and have a customer base sufficient to store a large amount of scram drainage discharged from the extraction side of all 1111 JIII rod drive mechanisms 2 during scram, and the bottom of the header 19 is connected to the drain valve 19a. , and the upper portion thereof is connected to a drain groove 190 via an overflow valve 19b. The drawn piping 4 of each water pressure control unit 5 is connected to the scram discharge header 19 via a scram outlet valve 20 and an isolation valve 20a on the drainage side, and the scram Yamaguchi valve 20 is opened and controlled during scram. The structure is such that a large amount of scram discharge water discharged from the rod drive mechanism 2 is sent into the scram discharge header 19.

The scram population valve 18 and the scram outlet valve 20 are held closed by air pressure within their respective diaphragms, and each diaphragm is provided with a solenoid valve 21.
．． Air for maintaining the valve open is supplied from an air supply device 23 via 22. Further, the solenoid valve 21.
22 is de-energized by a scram valve opening signal from the reactor emergency shutdown command system 24 for emergency shutdown of the reactor when a scram signal is generated, and the scram population valve 18 and scram exit valve 20 are deenergized by the air supply device. The air supply path leading to each diaphragm is shut off, the diaphragms are released to the atmosphere, and both valves 18 and 20 are opened.

Therefore, when a scram signal is generated, the solenoid valves 21 and 22 are de-energized by the scram valve opening signal output from the reactor emergency shutdown command system 23, and the scram population valve 18 and the scram outlet valve 20 are opened. As a result, the high-pressure scram water stored in the accumulator 16 is supplied to the insertion side of the control rod drive mechanism 2, and the control rods are inserted into the reactor core by 1.6 mm.
Fully insert it in ~3°5 seconds. Further, during this scram, a large amount of scram waste water is discharged from the withdrawal side of all the control rod drive mechanisms 2, and this scram waste water does not return to the drive water supply section 6 but is stored in the scram discharge header 19.

(Problems with the background technology) By the way, in the control rod drive hydraulic device with this configuration,
For example, when disassembling and inspecting the 11J control rod drive mechanism 2 during periodic plant inspections, in order to isolate the control rod drive mechanism 2 from the hydraulic 11JIll unit 5,
Isolation valves 3a and 4a are closed. Furthermore, scrum exit valve 2
0 and the scram drainage header 19 may be closed. After the inspection work is completed, those isolation valves 3a and 4a.

20a, but although the isolation valve 3a on the insertion pipe 3 side opened, they forgot to open the isolation valve 4a on the withdrawal pipe 4 side or the isolation valve 20a on the scram drainage header 19 side, and it remained fully open. In this case, if a scram signal is generated in this state, the scram population valve 18 and the scram outlet valve 20 are opened, and the water in the accumulator 16 is rapidly pushed out by the high pressure nitrogen gas in the nitrogen container 17. This water attempts to scram through the insertion pipe 3 to the control rod drive mechanism 2 at a pressure as high as 80 to 120 KgZaIg per unit area.
Since the valve a is closed and the water outlet is blocked, an extremely large internal pressure of approximately 400/9/aJg is applied inside the control rod drive mechanism 2. In this case, the control rod drive mechanism 2 expands outward and collides with the inner surface of the control rod drive mechanism housing 2a, making it impossible to drive the control rods thereafter.

-9= [Object of the invention] The present invention was made based on the above circumstances, and
The purpose of this is to prevent damage to the control rod drive mechanism even if the isolation valve on the drainage side closes before the isolation valve on the water supply side during a scram.
An object of the present invention is to provide a control rod drive hydraulic device that can reliably prevent deformation and the like.

[Summary of the Invention] In order to achieve the above object, the control rod drive hydraulic system of the present invention detects the respective opening degrees of the isolation valve on the handling piping side, which is the drainage piping during scram, and the isolation valve on the scram drainage header side. A scram inlet valve that monitors whether there is a situation that requires an emergency shutdown of the reactor and controls the inflow of high-pressure scram water into the insertion pipe, and a scram that controls the outflow of scram waste water from the withdrawal pipe. A reactor emergency shutdown command system that controls the opening and closing of the exit valve and a signal from the valve position detection device are input, and the scram of the reactor emergency shutdown command system is performed only when both isolation valves are fully open. 10- The present invention is characterized by comprising a determination device that permits the output of a valve opening signal to the artificial valve and the scram exit valve.

[Embodiment of the Invention] FIG. 2 is a piping system diagram of a control rod drive hydraulic system shown as an embodiment of the present invention, in which the same parts as in FIG. 1 are given the same reference numerals.

The control rod drive hydraulic device is a device for pressurizing condensate from the condensate storage tank 7a as described above, and for supplying drive water, cooling water, and high-pressure scram to the control rod drive mechanism 2. This control rod drive hydraulic system is provided with a valve position detection device 25 and a determination device 26.

The valve position detection device 25 detects the respective opening degrees of the isolation valve 4a on the side of the drawn pipe 4, which becomes the drainage pipe during scram, and the isolation valve 20a on the side of the scram drainage header 19, and the detection signal is sent to the judgment device 26. is input.

On the other hand, the determination device 126 controls the reactor emergency shutdown command system 24 as follows based on the detection signal from the valve position detection device 25. That is, the detection signal from the valve position detection device 25 causes the isolation valve 4a on the side of the drawn pipe 4, which becomes the drainage pipe during scram, and the scram drainage header 19
The opening degrees of the side isolation valves 20a are all 100% (fully open).
Only when it is confirmed that this is the case, the determination device 126 causes the reactor emergency shutdown command system 24 to output a signal to de-energize the solenoid valves 21. This prohibits the output of a signal that causes 22 to be de-energized. Therefore, a signal from the valve position detection device M25 indicating that neither one of the isolation valves 4a and 20a is fully open (for example, the opening degree of one valve 4a is 90% and the opening degree of the other valve 20a is 90%) is detected by the judgment device. 26, the reactor emergency shutdown command system 24 will not output a signal to de-energize the solenoid valves 21 and 22.

Next, the action will be explained.

During normal reactor operation, isolation valves 3a, 4a, and 20a are all open. In addition, if it becomes necessary to isolate part of the control rod drive mechanism 2 from the hydraulic control unit 5 for some reason, first close the isolation valve 3a on the insertion pipe 3 side, then isolate the extraction pipe 4 side. In the case of closing the valve 4a, essentially no problem occurs. However, when the isolation valve 4at on the pull-out pipe 4 side or the isolation valve 208 on the scram drainage header 19 side closes before the isolation valve 3a on the insertion pipe 3 side, at least one of the isolation valves 4a and 20a is other than fully open. While in this state, the determination device 26 uses the signal from the valve position detection device 25 to stop the output of the signal from the reactor emergency shutdown command system 24 indicating that the solenoid valves 21 and 22 are to be de-energized. .

When both the Fall I valves 4a and 20a are fully opened, output of the above signal from the reactor emergency shutdown command system 24 is permitted, and the scram population valve 18 and the scram outlet valve 20 are opened. This prevents the control rods from scrambling and increasing the internal pressure of the control rod drive mechanism 2 due to the scram, and prevents the control rod drive mechanism 2 from being damaged or deformed.

[Effects of the Invention] As detailed above, according to the present invention, when the isolation valve on the scram water discharge side is not fully open, the control rod scrams before the water outlet is blocked. Excessive water pressure on the control rod drive mechanism can be removed,
Damage, deformation, etc. of the control rod drive mechanism can be reliably prevented.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram showing a conventional example of a control rod drive hydraulic system for a boiling water reactor, and FIG. 2 is a piping system diagram of a control rod drive hydraulic system showing an embodiment of the present invention. 2... Control rod drive mechanism, 3... Insertion piping, 3a, 4
a, 2Qa... Isolation valve, 5... Water pressure control unit,
18...Scram population valve, 19...Scram drainage header, 20...Scram outlet valve, 21.22...Solenoid valve, 23...Air supply device, 24...Reactor emergency shutdown command System, 25... Valve position detection device, 26... Judgment device. Applicant's agent Patent attorney Takehiko Suzue 14-

Claims (1)

[Claims] A valve position detection device that detects the opening degree of the isolation valve on the withdrawal piping side that becomes the drainage piping during scram and the isolation valve on the scram drainage header side, and a valve position detection device that monitors the presence or absence of a situation that requires an emergency shutdown of the reactor, and A reactor emergency shutdown command system that controls the opening/closing of a scram population valve that controls the inflow of high-pressure scram water to the scram valve and a scram outlet valve that controls the outflow of scram waste water from the extraction pipe, and inputs signals from the valve position detection device. and a determination device that permits output of a valve opening signal to the scram population valve and the scram outlet valve of the reactor emergency shutdown command system only when both of the isolation valves are fully open. control rod-driven hydraulic equipment.