JPS60207090A - 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. The control rod drive mechanism housing 2a, of which only one is shown, is provided with a hydraulic control unit 5 via an insertion pipe 3 and a withdrawal pipe 4, although a large number of them are provided in the control rod drive mechanism 2.
is connected. Then, driving water is sent from this water pressure control unit 5 to the control rod drive machine m2, and each control rod is driven! ! ! The wastewater discharged from lt2 is transferred to the water pressure control unit 5.
will be returned to. Note that one hydraulic control unit 5 is provided 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 driving water supply unit 6 provided in each 1M 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 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 the pressure regulating valve 1o and is reduced in pressure to a predetermined pressure, and then is supplied as cooling water to each water pressure control unit 5 via the cooling water header 11a and the cooling water piping 11. Furthermore, a stabilizing valve 12.1 is connected in parallel with the pressure regulating valve 10.
3 are provided, and a portion of the driving water flows through these stabilizing valves 12.13.
The cooling water is supplied to each water pressure control unit 5 as cooling water, bypassing the pressure regulating valve 10. When the control rods are driven, when the flow rate of driving water supplied to the hydraulic control unit 5 increases, these stabilizing valves 12 and 13 are closed, reducing the flow rate sent as cooling water and reducing the flow of driving water.
It is configured to compensate for the increase and always ensure the required flow rate as driving water. 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 to another water pressure control unit (not shown) through the cooling water header 11a.

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 includes the drive water pipe 9, the cooling water pipe 11, and the drainage pipe. 14 are both connected to the insertion pipe 363 and the withdrawal pipe 4 via this directional control valve arrangement 15 and each isolation valve 3a, 4a.

The directional control valves 15a, 15b, 15c,
All valves 15d are closed when the control rod drive mechanism 2 is not driven. Then, the cooling water sent through the cooling water pipe 11 passes through the insertion pipe 3 to U 1b11 il! ]
It is supplied to the rod drive machine drive mechanism 2 side. This cooling water passes through an orifice (not shown) provided in the control rod drive mechanism 2 to the control rod drive mechanism 2 and the control rod drive mechanism housing 2.
a, cools the control rod drive mechanism 2, and then flows into the reactor pressure vessel 1.

In addition, when inserting a control rod, the direction control valves 15b, 15
c is opened, and driving water is supplied to the insertion side of the control rod drive mechanism 2 through the direction control valve 15c and the insertion pipe 3. At this time, the waste water discharged from the withdrawal side of the control rod drive TFIII 42 is returned to the driving water supply section 6 through the withdrawal pipe 4, the direction control valve 1511, and the drainage pipe 14.

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

The valve 15d is opened and driving water is supplied to the withdrawal side of the control rod drive t114112 through the direction II/III valve 15d and the withdrawal pipe 4. At this time, the waste water discharged from the insertion side of the control rod drive mechanism 2 passes through the insertion pipe 3, the direction control valve 15a, and the discharge water pipe 14, and is returned to the drive water supply section 6.

Further, 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 tube v13 via a scram 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 capacity sufficient to store a large amount of scram drainage discharged from the extraction side of all the control rod drive mechanisms 2 during scram, and the bottom gutter has a drainage valve 19a. After that, the upper part is the overflow valve 19b.
, and are connected to the drainage ditch 19c, respectively. The drawn pipe 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 during scram, this scram Yamaguchi valve 20 is opened and controlled. It is configured to send a large amount of scram discharge water discharged from the rod drive machine 4112 into the scram discharge header 19.

The scram population valve 18 and the scram outlet valve 20 are held in a closed state by air pressure within their respective diaphragms, and each diaphragm is provided with a 1f solenoid valve (
Air for maintaining the valve open is supplied from an air supply device 23 via scram valve pilot valves 21 and 22. Further, the solenoid valves 21 and 22 are 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 This shuts off the air supply to each diaphragm of the scram outlet valve 20, releases those diaphragms to the atmosphere, and opens both valves 18 and 20.

Therefore, when a scram signal is generated, the solenoid valves 21 and 22 are de-energized by the scram valve opening signal issued from the reactor emergency shutdown command system 24, 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. That is, during a scram, the scram inlet valve 1 is transferred from the accumulator 16.
8 and the insertion pipe 3 that reaches the insertion side of the control rod drive mechanism 2 via the isolation valve 3a becomes the scram water supply pipe A that supplies scram water. In addition, the extraction side hs 4 isolation valve 4a of the control rod drive mechanism 2, the scram outlet valve 20, the scram discharge line check valve 20b, the U-shaped seal 20G (1
'3 and the line including the pull-out pipe 4 leading to the scram discharge header 19 via the valves of the isolation valve 20a becomes the scram waste water discharge pipe B that discharges the scram waste water.

Note that it is not only the reactor emergency shutdown command system 24 that generates the signal to de-energize the solenoid valves 21 and 22, but also the scram test device 2 provided for each water pressure control unit 5.
5 also occurs in the solenoid valves 21 and 22 of each unit 5.

[Problems with the background technology] By the way, in a control rod-driven hydraulic system with such a configuration,
For example, during regular plant inspections, the control rod drive mechanism 2
When carrying out disassembly and inspection work, isolation valves 3a,
Close valve 4a. Furthermore, the isolation valve 20a between the scram outlet valve 20 and the scram drainage header 19 may be closed. After the inspection work is completed, those isolation valves 3a,
4a.

20a, but although the isolation valve 3a on the insertion pipe 3 side opened, he 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 closed. If the scram signal is generated in this state, the scram inlet valve 18 and the scram outlet valve 20 will be opened, and the water in the accumulator 16 will be rapidly pushed out by the high pressure nitrogen gas in the kiln container 17. Ru. This water is trying to be scrammed by the control rod drive mechanism 2 through the insertion pipe 3 at a high pressure of 80 to 120 Kfllct1g per unit area, but on the other hand, the isolation valve 4a or 20a on the drainage side is closed and the water outlet is blocked. Because of being
An extremely large internal pressure of about 400 Kfj/cd9 is applied inside the control rod drive mechanism 2. The same thing can be said if only the scram inlet valve opens when a scram signal is generated, but the scram outlet valve does not open for some reason.

In such a case, not only will the scram operation become impossible, but the control rod drive mechanism 2 will expand outward and collide with the inner surface of the control rod drive mechanism housing 2a, resulting in damage to the control rod drive mechanism and damage to the control rod drive mechanism. Due to deformation etc., subsequent 11111
I was used to not being able to drive one stick.

[Object of the invention] The present invention was made based on the above circumstances, and
The purpose of this is to enable scram operation even in the unlikely event that the valves inserted in the drainage pipe are not open during scram, and to prevent damage or deformation of the control rod drive mechanism. It is an object of the present invention to provide a control rod drive hydraulic device that can reliably prevent such problems.

[Summary of the Invention In other words, the control rod drive hydraulic system according to the present invention includes a scram water supply pipe that supplies high-pressure scram water to the control rod drive mechanism during a scram, and a scram water supply pipe that discharges scram drainage from the control rod drive mechanism to a scram drainage header during a scram. The scram water discharge piping includes a scram water discharge piping, a valve inserted in the scram water discharge piping, and a scram drainage relief mechanism inserted between the valve and the control rod drive mechanism. .

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a piping system diagram of the control rod drive hydraulic system according to this embodiment, in which the same parts as in FIG. A scram drainage relief mechanism 11 is branched and connected to the drawn piping 4 between the isolation valve 4a and the control rod drive mechanism 2. This scram drainage relief m structure 51 has the following configuration. Reference numeral 52 in the figure indicates a cylindrical pressure suppression container, and a piston 5 is contained in this pressure suppression container 52.
3 is slidably housed. The pressure suppression vessel 52
A hose 55 with an on-off valve 54 inserted therein is connected to the top of the piston 53, and nitrogen gas is sealed into the pressure suppression container 52 on the upper surface side of the piston 53 through a connection port 55a at the tip of the hose 55.

Further, a safety valve 56 is branched and connected to the hose 55, and the outlet side of the safety valve 56 is open to the atmosphere.

The operation will be explained based on the above configuration. First, as described above, nitrogen gas is sealed in the pressure suppression container 52 on the upper surface side of the piston 53 via the hose 55. Assume that a scram signal is generated in such a state. In this case, as described above, the reactor emergency shutdown command system 24 outputs the scram valve opening signal, the solenoid valves 21 and 22 are de-energized, and the scram population valve 18 and the scram exit valve 20 are opened. Furthermore, since the isolation valves 4a and 20a are opened in advance, the scram population valve 18 and the scram outlet valve 2
Scram operation is possible with a one-open valve of 0. Then, the high-pressure scram water contained in the accumulator 16 is supplied to the insertion side of the control rod drive machine 4fli2 to fully insert the control rods into the reactor core at high speed. On the other hand, a large amount of scram drainage is stored in the scram drainage header 19 via the drawn pipe 4. At that time, if the scram outlet valve 20 is inoperable or the isolation valves 4a and 20a are closed and the scram drainage discharge pipe B is blocked, the scram drainage will be discharged from the bottom surface of the piston 53 of the scram drainage relief mechanism 51. Flow into the side. The piston 53 is pushed upward by the inflow of this scram waste water, thereby absorbing the shock wave during the scram. At the same time, scram waste water is contained in the pressure suppression vessel 52 below the piston 53. The above piston 5
3, the nitrogen gas sealed in the upper surface of the piston 53 is compressed, and this compression maintains the pressure balance. In addition, the pressure suppression vessel 5 is compressed by the compression of the nitrogen gas.
When the pressure inside 2 exceeds a predetermined value, the safety valve 56 operates to release the pressure and prevent the pressure suppression container 52 from being damaged.

According to the control rod drive hydraulic system according to the present embodiment, in the unlikely event that the scram outlet valve 20 does not open when a scram signal is generated, or the isolation valves 4a and 20a are closed and the scram wastewater discharge pipe B is blocked. However, the scram drainage release mechanism 11 can contain the scram drainage and absorb the impact at that time, making it possible to perform the scram operation. Thereby, the control rod drive mechanism 2
Of course, it is possible to maintain the health of
It can significantly improve the safety of nuclear reactors.

The scram drainage relief mechanism i may also have a configuration in which the safety valve is directly connected to the scram drainage discharge pipe B. In this case, the pressure is set in advance, and the safety valve is activated by the pressure increase in the scram water supply pipe B during scram. The valve is opened to allow scram drainage to escape, thereby enabling scram operation.

Therefore, the same effects as in the embodiment described above can be achieved.

(Effects of the Invention) As detailed above, the control rod drive water pressure control device according to the present invention has a scram water supply pipe that supplies high pressure scram water to the control rod drive mechanism during a scram, and a scram water supply pipe that supplies high pressure scram water to the control rod drive mechanism during a scram. A scram water discharge piping for discharging scram drainage to a drainage header, a valve inserted in the scram water discharge piping, and a scram drainage relief mechanism inserted between the valve and the control rod drive mechanism. The configuration includes the following.

Therefore, even if the scram drainage discharge piping is blocked when a scram signal is generated, scram operation can be made possible. This not only maintains the integrity of the rod drive mechanism but also greatly improves the safety of the reactor. I can do it.

[Brief explanation of drawings]

FIG. 1 is a piping system diagram showing a conventional example of a control rod driving hydraulic system for an 'am water reactor, and FIG. 2 is a piping system diagram of a control rod driving hydraulic system showing an embodiment of the present invention. 2... Control rod drive mechanism, 3... Insertion piping, 3a, 4
a, 20a... Isolation valve, 5... Water pressure control unit,
18... Scram population valve, 19... Scram outlet valve, 21.22... Solenoid valve, 23... Air supply device,
24... Reactor emergency shutdown command system, A... Scram water supply piping, B... Scram wastewater discharge piping, 51...
Scram drainage relief mechanism. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A scram water supply piping that supplies high-pressure scram water to the control rod drive 1J11il during a scram, and a scram water discharge that discharges scram wastewater from the control rod drive mechanism to the scram drainage header during a scram. A control rod comprising piping, a valve inserted in the scram water discharge piping, and a scram drainage relief mechanism inserted between the valve and the control rod drive mechanism. Drive hydraulic equipment. (2) The scram drainage relief mechanism includes a pressure suppression vessel;
Claim 1, characterized in that the device comprises a piston slidably housed in the pressure suppression container, and nitrogen gas is sealed in the pressure suppression container on the upper surface side of the piston. control rod-driven hydraulic system. (3) The control rod drive hydraulic device according to claim 1, wherein the scram drainage relief mechanism is a safety valve branch-connected to the scram drainage discharge piping.