JPS6170488A - Emergency drive for control rod of nuclear reactor - 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] [Field of Application of the Invention] The present invention provides an emergency pivot device for a nuclear reactor control shaft drive mechanism, more specifically, by driving a hydraulic piston built in the control shaft drive mechanism. This invention relates to an emergency 2 drive device of a control rod drive mechanism for a boiling water reactor that inserts a control rod into the reactor in an emergency.

[Background of the invention]

FIG. 3 is an explanatory diagram of a control rod drive system of a conventional (boiling water type) nuclear reactor.

In FIG. 3, 1 is a control shaft drive mechanism having a hydraulic piston inside, 2 is a hydraulic second point of the control shaft drive mechanism 1, and 3
indicates a control rod-driven water pump, and the control rod *i# water pressure system is
It consists of a scram water supply system A for control rod insertion (scram) in an emergency, a control rod drive water supply system B for shim operation, and a control rod drive mechanism cooling system C.

A scram population valve 4 and a scram outlet valve 5 are connected to the scram water supply system A, and these scram valves 4,
5 is connected to a scram pilot valve 7a via an air supply pipe 8.
and 7b are connected. Furthermore, the scram water supply system B is connected to an achievator 9 that operates during reactor scram.

A scram pilot valve air header 10 is connected upstream of the air supply pipe 8 .

The control rod drive water supply system B includes a drive water control device 11 for controlling shim operation, and controls normal control rod insertion and removal operations. Also, known flow control valves 14 and pressure control valves 15 are provided at required locations.

A conventional control rod drive system for a boiling water reactor has the above configuration, and the control rod insertion (scram) operation in an emergency will be explained based on FIG.

In nuclear reactors, in order to quickly bring the reactor core to subcriticality in emergencies such as large earthquakes or abnormally high neutron flux,
Inserting the control rod. Generally, in a boiling water reactor, the above-mentioned emergency control rod insertion (scram) is performed using a hydraulic piston.

When a scram signal is issued in a reactor emergency, the scram pilot valve 7a, which is a -3-way electromagnetic switching valve.

7b changes from an energized state to a non-excited state, and the valve seat is switched. That is, when the scram pilot valve is in an energized state, air pressure from the scram pilot valve air header 10 is applied to the scram population valve 4 and the scram outlet valve 5. When the scram pilot valve becomes non-energized and switches due to the scram signal, the air pressure from the scram pilot valve air header 10 is cut off, and the air pressure applied to the scram valve 4.5 is discharged.

The scram valve 4 is an air-operated valve that is normally fully closed. When the air pressure to the scram valve 4 is cut off and discharged, the scram valve 4 is fully opened.

By fully opening the scram valve 4, high-pressure scram water, which is the drive source for the control rods stored in the accumulator 9, is supplied to the lower part of the hydraulic piston of the control shaft drive mechanism 1.

On the other hand, the scram outlet valve 5 is also an air-operated valve that is normally fully closed, and when the air pressure to the scram outlet valve 5 is cut off and discharged, it is similarly fully opened. When the scram outlet valve 5 is fully opened, the drive water above the hydraulic piston of the control shaft drive mechanism 1 is discharged into the scram water discharge container. As a result, the hydraulic piston is rapidly pushed upward and the control rod is inserted into the reactor.

In the above, the scram water supply system and the control rod drive water system are incorporated into the hydraulic unit 2.

Therefore, a hydraulic unit 2 is installed for each control drive mechanism, and for example, in a 1.1 million kWe atomic coupler plant, approximately 185 hydraulic units are required. The number of valves, scram pilot valves, accumulators, and other equipment increases significantly, and the number of factors that can cause problems with the hydraulic unit increases. In addition, incorporating a large number of valves and other equipment into the hydraulic unit 2 installed for each control S drive mechanism means that the time required for periodic plant inspection work becomes longer; , which is undesirable in terms of reducing radiation exposure for workers.

[Purpose of the invention]

The present invention has been made in consideration of the above points, and includes:
The purpose of this is, of course, to shorten the working time during periodic inspections of the plant and reduce the burden on workers.
The present invention aims to provide a reactor control rod emergency 1ql movement device that is also highly economical.

[-Summary of the invention]

In order to achieve the above object, the present invention provides a plurality of control P! Each of the I-rods is provided with a control rod drive mechanism independently, and each of the control rod drive mechanisms described above is operated by boiling water, which inserts the control rod in an emergency by driving a hydraulic piston built into each drive mechanism. In a type nuclear reactor, a scram water supply unit equipped with an emergency drive source for the hydraulic piston as well as an emergency device is configured to be shared by several control rod drive NJJ mechanisms. It is.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on an embodiment shown in FIG.

In FIG. 1, 1 is a control shaft drive mechanism having a hydraulic piston inside, 2 is a control rod, a hydraulic unit for a pivot mechanism 1,
Reference numeral 12 indicates a scram water supply unit that operates the hydraulic piston built in the control rod 1 moving mechanism 1 in an emergency. The control rod drive system pressure system is composed of a scram water supply system A, a control rod for shim operation, a drive water supply system B, and a control rod drive mechanism cooling system C.

The control rod drive water supply system B includes a drive water control device as in the conventional case.

Therefore, in the present invention, the scram water supply unit 12 described above is connected to a plurality of control rods 1.1...
However, in the illustrated embodiment, the control shaft drive mechanism 1 is
), and the scram valves 4a, 4b, 4c, 4d and the scram outlet valve 5a,
5b, 5c, and 5d are configured in series and in parallel, respectively.In the embodiment shown in FIG. 4d are arranged in series, and the valves 4b, 4! are connected to the valves 4a, 4c in series. Columns are arranged in parallel. Also, the valve 4a,
A tie line/13 is provided to connect the 4c row and the valves 4b and 4d rows. Scram outlet valves 5a, 5b.

5c, sd, and tie line 14 have similar configurations.

Further, one set of scram pilot valves 7a and 7b is provided for the shared scram supply water unit 12.

In other words, in the embodiment shown in FIG.
, 5a, . . . , 5d) fail to open, other valves are bank-amplified to supply and discharge scram water. Furthermore, even if one of the valves malfunctions and opens accidentally, the other valves are closed, so scram water is not supplied or discharged, and the hydraulic piston is accidentally activated. No control rods are inserted.

The present embodiment has the above-mentioned configuration, and the operation thereof will be explained below with reference to FIG. 1 regarding insertion of the control rod in an emergency.

When a scram signal is issued in a reactor emergency, the scram pilot valve 7a, which is a three-way electromagnetic switching valve.

7b is switched in the same manner as in the conventional example. That is, the air pressure from the scram pilot valve air supply source is cut off, and the air pressure applied to the scram valves 4a...4d, 5a...5d is discharged.

The scram valves 4a...4d are air-operated valves that are normally fully closed. Scrum population valve 4a...4
When the air pressure to d is discharged, the scram population valve 4a...
...4d is fully opened. Scrum population valve 4a...4
By fully opening d, high-pressure scram water, which is the three motive power sources for the control rods stored in the accumulator 9, is supplied to the lower part of the hydraulic piston of the control rod drive mechanism a.

Here, even if any one of the scram population valves 4a...4d does not fully open due to a failure, the other valves fully open, thereby supplying the scram water to the hydraulic piston. Furthermore, even if two valves do not fully open due to a failure, such as in the case of a combination of failure valves 4a and 40 or 4a and 4d, scram water can be supplied to the hydraulic piston by fully opening the other valves.

On the other hand, the scram outlet valves 5a...5d are also air-operated valves that are normally fully closed, and the scram outlet valves 5a...
...When the air pressure to 5d is discharged, it opens fully in the same way. By fully opening the scram outlet valves 5a...5d, the drive water above the hydraulic piston is discharged into the scram discharge container. At this time, similar to the scram valve, even if one or two of the scram outlet valves 5a...5d does not fully open due to a failure, the other valves will open to the full mL, and the drive water will flow. be discharged.

As a result, the hydraulic piston is pushed upward rapidly,
Control rods are inserted into the reactor.

Since the scram water supply unit 12 is configured to be shared by a plurality of control rods, a plurality of control rods can be rapidly inserted at the same time by fully opening the scram population valve and the scram outlet valve.

Therefore, according to the present embodiment having the above configuration, a plurality of scram water supply units 12 equipped with a drive source and a control device for rapid driving of the hydraulic piston built in the control drive mechanism 1 in an emergency are provided. Control drive mechanism 1
, 1...... By configuring it to be shared,
The number of valves used in the scram water supply unit can be significantly reduced compared to conventional nuclear reactor plants.

Reducing the number of valves used in a scram water supply unit means that the causes of trouble are removed from the unit, and the MTBF (Mean Time Between Failures) is reduced.
1a1lure), which is very effective in improving the reliability of equipment during nuclear reactor operation.

In addition, the scram water supply unit 12 is shared by a plurality of control drive mechanisms 1.1.
Reducing the number of valves and other equipment incorporated in the reactor plant as a whole contributes to improving the efficiency of periodic plant inspection work and is also effective in reducing radiation exposure for workers. Furthermore, the scram water supply unit 12
The reduction in the number of valves and devices incorporated in the system means that the installation of piping equipment can be omitted, which is effective in reducing piping equipment costs.

Fig. 2 shows another embodiment of the present invention, Fig. 3 (a) is an arrangement diagram of the control rod drive water pressure unit, and Fig. 3
FIG. 2 is an explanatory diagram of the drive system of the hydraulic unit shown in FIG.

In FIG. 2, the same reference numerals as in FIG. Water pressure unit 2'.

In this embodiment, the entire control drive mechanism 1, 1...'f
! : It is divided into two blocks and each block is equipped with a shared scram water supply unit 12, and according to the above configuration, compared to a case where a single scram water supply unit is used, It is possible to shorten the length of the piping and provide ample space between the installed piping, which is convenient for on-site work.

In another embodiment, the pivoting water control device 11 can also be combined with a scram water supply unit and shared by a plurality of control drive mechanisms. Furthermore, for control rods and moving devices that use electric motors for shim operation and hydraulic pressure for scram operation, by sharing the scram water supply system as in this example, it is possible to reduce the need for hydraulic piping equipment. It becomes possible to achieve a significant reduction.

〔Effect of the invention〕

As detailed above, the present invention not only improves the reliability of equipment during reactor operation, shortens work time during periodic plant inspections, and reduces radiation exposure for workers, but also improves economic efficiency. Excellent reactor control rod emergency drive system f1
It can be provided.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a nuclear reactor lj control rod drive system showing one embodiment of the present invention, FIG. Figure (B) is an explanatory diagram of the drive system of the hydraulic unit shown in Figure 2 (A), and Figure 3 is an explanatory diagram of the control rod drive system of a conventional (boiling water) nuclear reactor. A...Scram water supply system, B...Control rod drive water supply system, C...Control rod drive mechanism cooling system, 1...Control rod drive mechanism, "2.2' and 2"...・Hydraulic unit),
4a, 4b. 4c, 4d--Scrum population valve, 5a, 5b, 5c. 5d...Scram outlet valve, 7a, 7b...Scram pilot valve, 12.12' and 12''...Scram water supply unit, 9...Accumulator.

Claims (1)

[Claims] 1. A plurality of control rods arranged in the reactor are each provided with an independent control rod drive mechanism, and each of the control rod drive mechanisms drives a hydraulic piston built into each drive mechanism. In a boiling water reactor, in which a control rod is inserted into the reactor in an emergency, a plurality of control rod drive hydraulic units equipped with an emergency drive source and a control device for the hydraulic piston are controlled. A nuclear reactor control rod emergency drive device characterized by having a configuration that is shared by a rod drive mechanism.