JPH04181199A - Control rod drive mechanism - Google Patents

Abstract

PURPOSE:To prevent flowing-in of driving water into which air and foreign substance such as crudes are mixed, to a control rod driving machine by making one of filters which are installed, in a plurality of units, in a piping of control rod driving hydraulic pressure system in order to filtrate the driving water, to be a hollow fiber membrane filter. CONSTITUTION:During normal operation, water from a condensate demineralizer 3 passes through a suction filter 5 and pressurized by a driving water pump 4 and then, after passing through a hollow fiber membrane filter 28, a part of the water is supplied to a control rod drive mechanism via a flow regulating value 8 and a pressure regulating valve 10 and another part of the water is supplied as purging water for mechanical seals of a pump 30. Foreign substances mixed into the driving water are, for the first place, removed by passing through the filter 5. However, the filter 5 can not remove fine insoluble solids and then the water enters the pump 4 and discharged to the filter 28, where the solids are almost completely removed. Therefore, the driving water coming out of the filter 28 is pure and clean water. By these procedures, abnormality such as biting the foreign substances in the driving water can be prevented and driving function of the mechanism can be kept at rather stable condition.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a control rod drive device, particularly a control rod drive hydraulic system that supplies drive water to the control rod drive mechanism, which has been improved. It relates to a drive device.

(Prior Art) A control rod drive system of a control rod drive device of a conventional general boiling water nuclear power plant will be described with reference to FIGS. 4 and 5. The control rod drive system mainly consists of a control rod drive mechanism and a hydraulic control unit provided for each control rod, and a control rod drive hydraulic system common to all control rods. FIG. 4 shows the configuration of the control rod drive mechanism and hydraulic control unit, and FIG. 5 shows a schematic system diagram of the control rod drive hydraulic system.

In FIG. 4, the control rod drive mechanism 1 employs a hydraulic piston drive system, and is mainly composed of a drive piston La, an index tube 1b, and a locking mechanism 10. The drive piston 1a is attached to the lower part of the index tube 1b, has upper and lower pressure-receiving surfaces, and inserts and withdraws the control rod based on the pressure difference between the upper and lower surfaces. Also, index tube 1b
A locking groove is provided on the outer peripheral surface of the IC, and a locking mechanism such as a ratchet type collet finger can be used.
The control rod is moved and held by a certain fixed stroke, so that the control rod can be fixedly held in a predetermined position.

The system that supplies and adjusts the water pressure and flow rate necessary for the operation of these control rods is the hydraulic control unit 2 shown in Figure 4 attached to each control rod, and the control system common to all control rods in Figure 5. It consists of a rod-driven hydraulic system.

This control rod drive hydraulic system is a system for supplying desalinated condensate from the condensate desalination device 3 to the control rod drive mechanism 1 during plant operation, and includes a drive water pump 4, a suction filter 5, Driving water filter 6, flow nozzle 7 as a flow rate measuring device, flow rate adjustment valves 8, 9, pressure adjustment valve 1 (1, 1
1, a stabilizing valve 12, etc.

The driving water sent from the condensate desalination device 3 by the driving water pump 4 is passed through two types of filters, namely a suction filter 5 and a driving water filter, which removes foreign substances that may cause malfunctions of the control rod drive mechanism 1, etc. A portion of the water passes through the filter 6 and flows to the filling water header 13 as a scram hydraulic system. In addition, some parts include a flow rate adjustment valve 8 for maintaining the filling water pressure.
9, the water flows to a drive water header 14, which is a drive water pressure system that operates the control rod drive mechanism 1, and a cooling water header 15, which is a cooling water pressure system for the control rod drive mechanism piston seal.

Here, the filling water header 13, driving water header 14, and cooling water header 15 in FIG. 5 are each connected to the header section in FIG. 4.

The stabilizing valve 12 is composed of two solenoid valves installed in parallel, and the flow rate of one of the stabilizing valves under normal conditions is equal to the flow rate required for the control rod insertion operation of the control rod drive mechanism 1, and the flow rate of the other stabilizing valve is equal to the flow rate required for the control rod insertion operation of the control rod drive mechanism 1. The flow rate is adjusted to be equal to the flow rate required for extraction. The water exiting the stabilizing valve 12 is then circulated to the cooling water piping. That is, when one of the stabilizing valves 12 is closed during drive operation, a predetermined flow rate flows toward the control rod drive mechanism 1, allowing operation to be performed while keeping the water pressure at the pressure regulating valve 10 constant. There is.

Furthermore, piping from the drainage header 16 is connected to the downstream side of the stabilizing valve 12, and during operation, the drainage flowing from the drive water header 14 through the control rod drive mechanism 1 to the drainage header 16 is directed to the cooling water header 15. and is discharged into the reactor pressure vessel through another hydraulic control unit 2. This drainage header 16 is connected to the drainage header 16 in FIG. 4.

During normal operation, only cooling water flows, with a constant flow rate sufficient to cool all the control rod drive mechanisms 1, and from each header 13 to 16, the same number of pipes as the control rods are connected to each water pressure control. Leads to unit 2.

In addition, a condensate storage tank (tank) 18 is included in the control rod drive hydraulic system.
is provided, and the water source of driving water can be switched from the condensate desalination device 3 to the condensate storage tank (tank) 18.

The hydraulic control unit 2 supplies filling water, cooling water, and driving water from the control rod drive hydraulic system to the control rod drive mechanism 1, and one unit is provided for each control rod.

As shown in FIG. 4, the water pressure control unit 2 includes four electromagnetic selection valves 21, 22, 23, 24 and two scram valves 2.
5.2B is assembled into a unit.

This water pressure control unit 2 operates as follows.

When inserting the control rod, use the solenoid selection valve 21°22 for insertion.
is opened, water pressure applied to the rudder 14 is applied to the lower surface of the driving piston 1a, and water on the upper surface is discharged to the discharge header 1B. Conversely, when pulling out, insert solenoid selection valve 2.
1.22 for a short period of time to raise the index tube 1b slightly to make it easier to unlock the collet finger, open the extraction solenoid selection valve 23.24 to apply driving water pressure to the upper surface of the driving piston la. The water on the lower surface is discharged to the discharge header 16. At the same time, spread the collet fingers along the guide and insert the index tube ib.
Pull out the control rod by separating it from the control rod so that it can be pulled out freely. During scram operation, by opening the scram valves 25 and 28, high-pressure water flows from the filling water header 13 to the lower surface of the drive piston 1a, and water on the upper surface of the drive piston 1a is discharged to the scram discharge header 27 at atmospheric pressure. This allows for rapid scrum operations.

With the above configuration, the control rod drive system changes the position of the control rods in the reactor core in response to manual control signals, increases or decreases the output at low output, adjusts the long-term reactivity, and controls the reactor. The internal output distribution has been adjusted.

Further, the condensate purified by each filter in the control rod drive hydraulic system is also used as purge water for the mechanical seal of the reactor coolant recirculation pump 30.

Mechanical seals must be replaced as consumables during periodic inspections, or they come into contact with reactor water, which can trap strong radioactivity. For this reason, purified condensate at a pressure higher than the reactor pressure is supplied as purge water for mechanical seals to prevent workers from being exposed to radiation.

(Problems to be Solved by the Invention) As mentioned above, the conventional control rod drive system has a purpose of purifying the drive water of the control rod drive mechanism 1 that drives the control rods and removing foreign substances such as crud. Two types of filters are installed, that is, a suction filter 5 with an absolute filtration performance of about 251 mm is installed on the inlet side of the drive water pump 4 that pressurizes the drive water, and a driven water filter 6 with an absolute filtration performance of about 50 μm is installed on the outlet side, respectively. This filters the drive water of the control rod drive mechanism 1. The purified condensate is also supplied as purge water for the mechanical seals of the reactor coolant pumps.

However, with this filtration performance, it is difficult to completely remove foreign substances such as minute rads, and the control rod drive mechanism 1
There is a possibility that leakage may occur due to foreign matter getting into the control rod drive hydraulic control unit 2, or foreign matter getting caught in the mechanical seal of the reactor coolant recirculation pump that supplies purge water from the control rod drive hydraulic system. . Additionally, air may get mixed into the control rod drive hydraulic system during operations such as overhauling and inspecting each device or switching water sources. There was a problem that Ghent work had to be carried out sufficiently to remove the air as it would cause some damage.

The present invention has been made in view of the above circumstances, and it improves the filtration performance to the extent that it can almost completely remove foreign matter mixed into the control rod drive hydraulic system, and also makes it possible to collect air, thereby eliminating foreign matter and air. It is an object of the present invention to provide a control rod drive device that is capable of supplying contamination-free drive water to a control rod drive mechanism.

[Structure of the Invention] (Means for Solving the Problem) In order to achieve the above object, a control rod drive device according to the present invention includes a control rod drive mechanism that drives control rods of a boiling water reactor. In a control rod drive device in which drive water for driving a control rod drive mechanism is supplied from a drive hydraulic system, one of a plurality of filters for purifying drive water installed in piping of the control rod drive hydraulic system is provided. It is characterized by being a hollow fiber membrane filter.

(Function) According to the present invention configured as described above, the hollow fiber membrane filter substantially removes insoluble solids in the liquid by the filtration holes of 0.1 or less on the surface of the hollow fibers of the filter. Since it can be completely removed and air does not pass through, the drive water for the control rod drive mechanism is filtered by passing it through a hollow fiber membrane filter inside the control rod drive hydraulic system, thereby removing crud, etc. It is possible to prevent drive water mixed with foreign matter or air from flowing into the control rod drive mechanism, etc.

Furthermore, since the mechanical seal purge water of the reactor coolant recirculation pump can be purified, it is possible to prevent foreign matter from entering the mechanical seal.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic system diagram of a control rod drive hydraulic system according to a first embodiment of the present invention. In addition, the same parts in the drawing as in FIG. 5 are indicated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

In this embodiment, one of the two driving water filters 6 installed on the outlet side of the driving water pump 4 in the conventional example shown in FIG. 5 is replaced with a hollow fiber membrane filter 28. Here, the driving water filter 6 uses a conventional notched wire type or the like.

In this embodiment, during normal operation of the nuclear power plant, water from the condensate desalination device 3 passes through the suction filter 5, is pressurized by the drive water pump 4, and then passes through the hollow fiber membrane filter 28. A portion of the water is supplied to the control rod drive mechanism 1 via the flow rate regulating valve 8 and the pressure regulating valve 10, and a portion is supplied as purge water for the mechanical seal of the reactor coolant recirculation pump 30.

Here, foreign substances such as crud mixed into the drive water are first removed by passing through the suction filter 5. However, the suction filter 5 enters the drive water pump 4 without removing minute insoluble solids of 251 or less, and is discharged from the pump 4 to the hollow fiber membrane filter 28. This hollow fiber membrane filter 28 captures even about 0.11 crud, and almost completely removes the solid content. Therefore, the driving water that exits the hollow fiber membrane filter 28 is clean water that is free of foreign matter. Therefore, it is possible to prevent malfunctions such as malfunctions of the control rod drive mechanism 1 due to foreign objects being caught in the drive water, and to maintain stable drive performance.

In addition, since the purge water for the mechanical seal of the reactor coolant recirculation pump 3o is branched from the control rod drive hydraulic system, the control rod drive water is purified and at the same time, the purge water for the mechanical seal of the reactor coolant recirculation pump 30 is Since the mechanical seal purge water is also purified, it is possible to prevent foreign matter from getting caught in the mechanical seal, thereby reducing the possibility of leakage.

Furthermore, in the conventional example shown in FIG. 5, during plant construction, during periodic inspections, when disassembling equipment, and when switching the water source from the condensate desalination device 3 to the condensate storage tank (tank) 18,
It was necessary to carry out sufficient vent work to remove air, but in this example, the hollow fiber membrane filter 28 is installed on the outlet (discharge) side of the drive water pump 4 of the control rod drive water pressure supply system. , air is collected by this hollow fiber membrane filter 28. This greatly reduces venting work and
It can be simplified, and the load on the construction process and periodic inspection process can be reduced, making it possible to operate economically.

By the way, in this embodiment, for the two control rod drive water filters, one drive water filter 6 such as a conventional notch wire type filter and one hollow fiber membrane filter 28 are installed in parallel. Since the hollow fiber membrane filter 28 needs to be replaced periodically, the driven water filter 6 such as a notched wire filter is used when the hollow fiber membrane filter is replaced, and the hollow fiber membrane filter 28 is used at other times. Is it possible to consider using hollow fiber membrane filters for the two filters? In the case of hollow fiber membrane filters, crud, etc. will adhere even if they are installed without filtering the driving water, so it is difficult to actually use them. Hollow fiber membrane filters that have not been used must also be replaced periodically. In other words, installing a hollow fiber membrane filter in a filter section that is not normally used increases the replacement work.
This would be economically disadvantageous, and waste would also increase. On the other hand, in the case of a notch wire type filter, it can be used semi-permanently, and the time required to replace the hollow fiber membrane filter is short. In this embodiment, since the notch wire type filter is used only when replacing the hollow fiber membrane filter, the replacement work can be reduced and the amount of waste can be halved, which is also economically advantageous. Furthermore, by installing different types of filters, the redundancy of the filter function can be improved and loss of function due to a single trouble can be prevented.

Next, FIG. 2 shows a schematic system diagram of a control rod drive hydraulic system according to a second embodiment of the present invention. In the figure, the same parts as in FIG. 5 and FIG. 1 are indicated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

In this embodiment, one of the two suction filters 5 installed on the inlet side of the driving water pump 4 in the conventional example shown in FIG. 5 is replaced with a hollow fiber membrane filter 28.

The drive water from the condensate desalination device 3 passes through a hollow fiber membrane filter 28 before entering the drive water pump 4, where foreign matter is removed.

With the above configuration, the same operations and effects as in the first embodiment can be obtained in the second embodiment.

Further, in the case of this embodiment, since the drive water from which foreign objects have been removed enters the drive water pump 4, the performance of each device can be maintained while preventing the drive water pump 4 from being jammed by foreign objects.

Next, FIG. 3 shows a schematic system diagram of a control rod drive hydraulic system according to a third embodiment of the present invention. In the drawings, the same parts as in FIG. 5, FIG. 1, and FIG. 2 are indicated by the same reference numerals, and the explanation of the overlapping parts will be omitted.

In this embodiment, when only one suction filter 5 is installed on the inlet side of the driving water pump 4 in the conventional example shown in FIG. 5, this suction filter 5 is replaced with a hollow fiber membrane filter 28. be.

With the above configuration, the same actions and effects as the first and second embodiments can be obtained in the third embodiment. [Effects of the Invention] As described above, according to the present invention, the hollow fiber membrane It is possible to prevent foreign matter such as crud from entering the drive water supplied from the control rod drive water pressure supply system to the control rod drive mechanism via the filter, thereby preventing malfunctions of the control rod drive mechanism. It is possible to maintain stable driving performance.

In addition, the purge water of the mechanical seal of the reactor coolant recirculation pump branched from the control rod drive hydraulic system is also purified, which prevents foreign matter from entering the mechanical seal and reduces the possibility of leakage.

In addition, even if air gets mixed into the driving water during plant construction, periodic inspections, disassembly work, or even when switching water sources, this air will be collected by the hollow fiber membrane filter and will not pass through, making venting work easier. This has the effect of reducing vent work time significantly and enabling more economical operation.

Furthermore, by installing different types of filters, it is possible to improve the redundancy of the filter function and prevent loss of function due to a single trouble.

[Brief explanation of drawings]

FIG. 1 is a schematic system diagram showing a control rod drive hydraulic system of a control rod drive device according to a first embodiment of the present invention, and FIG. 2 is a control rod drive system of a control rod drive device according to a second embodiment of the present invention. A schematic system diagram showing a hydraulic system; FIG. 3 is a schematic system diagram showing a control rod drive hydraulic system of a control rod drive device according to a third embodiment of the present invention;
The figure is a configuration diagram showing the relationship between the control rod drive mechanism and the hydraulic control unit of a boiling water nuclear reactor, and FIG. 5 is a schematic system diagram showing the control rod drive hydraulic system of a conventional control rod drive device. 1... Control rod drive mechanism 2... Water pressure control unit 3... Condensate desalination device 4... Drive water pump 5.
...Suction filter 6... Drive water filter 7... Flow nozzle 8.
9... Flow rate adjustment valve 10.1.1... Pressure regulation valve 12... Stability valve 13... Filling water header 1
4... Ivy to drive water 15... Cooling water header 16
... Drain header 18 ... Condensate storage tank 21,
22.23.24...Solenoid selection valve 25, 28...Scrum valve 27...Scram drainage header 28/Hollow fiber membrane filter Agent Patent attorney Noriyuki Chika @1 Figure 3 Figure 4

Claims (2)

[Claims] (1) In a control rod drive device in which drive water for driving the control rod drive mechanism is supplied from a control rod drive hydraulic system to a control rod drive mechanism that drives the control rods of a boiling water reactor, the control rod drive mechanism A control rod drive device characterized in that one of a plurality of filters installed in piping of a hydraulic system for purifying drive water is a hollow fiber membrane filter. (2) A claim characterized in that one of the two filters for purifying drive water installed in parallel behind the drive pump installed in the piping of the control rod drive hydraulic system is a hollow membrane filter. Item 1. The control rod drive device according to item 1.