JPH0216493A - Hydraulic controller for driving control rod - Google Patents

Abstract

PURPOSE:To facilitate read of a pressure gauge, and also, to eliminate the degrease of thickness due to a fact that moisture is stuck to a bursting plate and it is corroded by providing an instrumentation block on the upper part of a nitrogen container and attaching the pressure gauge and the bursting plate to this instrumentation block. CONSTITUTION:A pressure gauge 21 and a bursting plate 18 are attached to the upper instrumentation block 39 attached directly to the top part of a nitrogen container 14. As a result, since the pressure gauge 21 can be placed in the vicinity of a position of eyes, read of scale is facilitated. Also, since the bursting plate 18 is placed in the most distant position from water in the upper part of the nitrogen container 14, the sticking of moisture which becomes a factor of corrosion can be prevented, therefore, it can be eliminated to deteriorate a scram function due to unexpected bursting caused by the degrease of the thickness of the bursting plate 18.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control rod drive system for nuclear power generation equipment,
In particular, the present invention relates to a control rod drive hydraulic pressure control device suitable for a boiling water type (hereinafter referred to as BWR) nuclear reactor emergency shutdown system.

[Conventional technology]

The control rod drive system of a BWR reactor consists of a control rod drive water pump, water pressure control device, insertion/extraction drive piping, flow rate, pressure control valve, detector, measuring instrument, etc., and controls the operation of the control rod drive mechanism. The basic system is shown in Figure 3. This system controls the flow rate and pressure required for the control rod drive mechanism and supplies them to the control rod drive mechanism.

(Pumps, flow rate, pressure control valves, detectors, measuring instruments, etc. are not shown in the diagram.) Control rod operations include regular insertion and withdrawal according to pre-planned patterns, and emergency insertion (scram) in the event of an abnormality in a nuclear power plant. ), that is, there is unsteady insertion, and during steady insertion, the insertion drive valve 27 and the insertion discharge valve 29 are opened by the insertion signal in FIG. ．． Check valve 46. Insertion drive valve 2
7. Water is sent to the insertion side water chamber 7 of the control rod drive mechanism 2 via the insertion side piping 10, pressurizing the piston head lower part 4 of the piston rod 3 connected to the control rod, and the water in the extraction side water chamber 6 is sent to the insertion side water chamber 7 of the control rod drive mechanism 2. Engineering 1. The control rod is discharged to the exhaust ladder 42 through the insertion and discharge valve 29 and inserted into the reactor. Also, during steady withdrawal, the drive water is supplied to the withdrawal drive valve 30 by the withdrawal signal. Then, the extraction discharge valve 28 opens, and the drive water header 41. Check valve 46. The piston head 4 enters the extraction side water chamber 6 through the extraction side piping 11.
The upper part of the control rod is pressurized, and the water in the insertion side water chamber 7 passes through the insertion side piping 10° and the withdrawal discharge valve 28, and is discharged to the discharge ladder 42, and the control rod is withdrawn from the inside of the reactor.

System operation during unsteady insertion, that is, scram, is performed by the piston type accumulator 13 built into the hydraulic control device 40.
There are three types of driving: one is driven by water pressure via the piston 37 by the nitrogen gas 16 accumulated in the reactor, the other is driven by the reactor water pressure in the reactor pressure vessel 1, and the other is driven by both. , the selection is determined by the level of reactor water pressure when a scram occurs. In a conventional control system for a BWR type nuclear reactor, nitrogen gas 16 is stored in a nitrogen container 14 at a rate of about 8
The scram drive water in the water chamber 24, which is filled with 0 kg/a# and connected to the nitrogen gas chamber 17 of the piston-type accumulator 13 through the accumulator connecting pipe 15 and partitioned by the piston 37, is pressurized.

A rupture disc 18 is installed in the middle of the connecting pipe 15 to protect the accumulator from abnormally high pressure of nitrogen gas. Pressure gauge 21. to monitor abnormally low pressure. Pressure switch 22 for detection, and
A level switch 19 is provided to detect water leakage from the seal portion of the piston 37. In the steady state, the inlet scram valve 25° and the check valve 35 are closed, and the water chamber 2
The pressure inside 4 is in balance with the nitrogen gas pressure. In addition, the reactor pressure scram system is connected to the reactor water inlet 5 provided in the reactor pressure vessel 1. It is configured such that reactor water is guided to the insertion side piping via a reactor water introduction pipe 8 and a check valve 9. When the furnace pressure is low, the scram signal activates the inlet scram valve 2.
5, the outlet scram valve 26 is opened, and the scram drive water in the water chamber 24 is introduced into the insertion side water chamber 7, and the piston head 4
is pressurized, and the water in the ice chamber 6 on the extraction side is pumped through the extraction side piping 11. The scram accumulator is discharged to the rudder 43 through the outlet scram valve 26 for scram discharge, and scram is performed.Since the scram accumulator is pressurized with nitrogen gas, its discharge pressure is dependent on the control rod insertion ratio, that is, the scram drive water discharge capacity. Since the relationship pv=changes under constant conditions, when the discharge pressure becomes lower than the reactor pressure, the check valve 9 opens and scram with reactor water is performed.

An example of the structure of the water pressure control device is shown in FIG. Water pressure control equipment requires a large number of equipment and piping in a small space.

In order to efficiently store valves and the like, the heavy objects of the accumulator 13 and nitrogen container 14 are placed on the lower side for stability. Therefore, the piping 15 connecting the accumulator 13 and the nitrogen container 14 is located at the lowest stage, and instruments for monitoring pressure inside the container and monitoring leakage water are also concentrated at the lowest stage. Since the pressure gauge 21 and the rupture disc 18 are arranged at the lower stage, it is difficult to read the scale of the pressure gauge 21 while patrolling, and the rupture disc 18 is also attached to the bottom where water tends to accumulate. The communication pipe 15 is a manifold, and the rupture disc 18. Level switch 19. Cartridge valve 20. Pressure gauge 21. A pressure switch 22 is also attached. The inside of the manifold has a complicated shape due to the parts attached to it, and if water gets in it, it will be difficult to remove.

This water intrusion route is caused by leakage from the piston 37 seal.
Also, water for calibration of the level switch 19 can be considered. This water remains in the manifold and blows nitrogen gas,
Alternatively, it scatters during filling and adheres to the rupture disc 18. If corrosion products such as chlorine were attached to the rupture disc 18, the thickness of the rupture disc 18 would decrease due to corrosion, and there was a risk that the rupture disc 18 would be ruptured at a pressure lower than the intended pressure.

[The problem that the invention attempts to solve]

In the above conventional technology, the mounting position of the pressure gauge for monitoring the nitrogen gas pressure, which is one of the purposes of patrolling around the water pressure control device, is located low at the bottom of the nitrogen container, and does not take into account the fact that the pressure gauge can be read while walking. , there was a problem in terms of visibility. The rupture disc is provided to protect the pressure vessel, and is made of a thin metal plate so that it ruptures at a pressure lower than the allowable pressure of the pressure vessel. In order to rupture at the predetermined pressure, it is necessary to keep the plate thickness constant, and thinning due to a corrosive environment is the most important thing to avoid. Moisture plays an important role in corrosion, but the rupture disc is installed at the bottom of the IJ, where water easily collects and accumulates, and no consideration has been given to the corrosion environment, resulting in corrosion and thinning of the IJ. There was a risk of external rupture.

An object of the present invention is to facilitate monitoring of a pressure gauge during patrol and to improve the accuracy of bursting a rupture disc.

[Means to solve the problem]

The above object is achieved by providing an instrumentation block on top of the nitrogen container and mounting a pressure gauge and a rupture disc on this instrumentation block.

The hanger at the top of the nitrogen container is made into a large block, and this is used as an instrumentation block. The problem was solved by relocating the pressure gauge and rupture disc here.

[Effect]

In addition to the instrumentation block at the bottom of the nitrogen container, an instrumentation block that also serves as a hanging bracket is installed on the top of the nitrogen container, and a pressure gauge is attached to the instrumentation block to detect pressure. The scale can be placed close to the eye, making it easier to read the scale. In addition, the rupture disc is located at the top of the nitrogen container farthest from the water, which prevents moisture from adhering to it, which can cause corrosion, and prevents damage to the scram function due to unplanned rupture due to thinning of the cover plate. do not have.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

The water pressure control device has a length x width x height of 500 x 550 x 370.
A large number of devices in a small space of 0 (mm).

Contains piping, valves, etc. The heavy objects of the accumulator 13 and nitrogen container 14 are placed on the lower side for stabilization. A level switch 19 for detecting leakage from the seal part of the piston 37 inside the accumulator 13 is attached to the lowermost instrumentation block 38, and the pressure gauge 21 and the rupture disc 18
is attached to an upper instrumentation block 39 that is attached directly to the top of the nitrogen container 14. Therefore, the scale of the pressure gauge 21 becomes easy to read, and the rupture disc 18 is not affected by water, so that thinning due to corrosion can be prevented.

In Figure 1, 31 to 34 and 36 are valves, 39 is an upper instrumentation block, 44 is a driving water header, and 45 is a check valve.

〔Effect of the invention〕

According to the present invention, the pressure gauge can be easily read during patrol, and the rupture disc is not affected by water.

Therefore, there is no wall thinning caused by moisture adhering to the rupture disc and corroding it.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a water pressure control device according to an embodiment of the present invention, FIG. 2 is a front view of FIG. 1, FIG. 3 is a system diagram of a conventional water pressure control device, and FIG. 4 is a system diagram of a conventional water pressure control device. It is a front view. 1... Reactor pressure vessel, 2... Control rod drive mechanism, 13
...Accumulator, 14...Nitrogen container, 18...
- Rupture disc, 19... Level switch, 20... Isolation valve, 21... Pressure gauge, 22... Pressure switch.

Claims (1)

[Claims] 1. In the control rod drive system of a boiling water reactor, a pressure gauge for monitoring the gas pressure in the scram accumulator is installed on the top of a vertical cylindrical nitrogen container, and a rupture disc is installed on the top of the nitrogen container. Features a control rod-driven hydraulic control device.