JPH0862366A - Control rod drive - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a control rod drive device capable of increasing the operating rate of a plant. [Structure] This device comprises a plurality of control rod drive mechanisms for driving a plurality of control rods 6, a plurality of first water supply systems for supplying high-pressure water for driving the control rod drive mechanisms, and a plurality of first water supply systems. The second water supply system connected to the first water supply system via the high-pressure water distribution means (filling water header 5, purge water header 17) to supply high-pressure water, the first water supply system to the control rod drive mechanism 6 It is composed of a logic circuit 26 and the like for controlling the supply of high pressure water to.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control rod drive device,
In particular, the present invention relates to a control rod drive device that supplies high-pressure scrum water to a motor / water pressure control rod drive mechanism.

[0002]

2. Description of the Related Art FIG. 5 is a vertical cross-sectional view of the core of a conventional boiling water nuclear reactor. A reactor pressure vessel 27 has a core 29 loaded with a large number of fuel assemblies 28 and a shroud 30. A large number of control rod drive mechanisms 6 are installed at the bottom of the reactor pressure vessel 27. The upper end of the control rod drive mechanism 6 is connected to a control rod 31 which is arranged between the fuel assemblies 28 and controls the reactivity of the nuclear reactor. The control rod 31 can be stored in the control rod guide tube 32 below the reactor core 29 in the shroud 30.

The control rod drive mechanism 6 is incorporated into the control rod drive mechanism housing 33 from below, and a motor 34 is installed at the lower end of the control rod drive mechanism 6, and the core of the control rod 31 is driven by the motor 34. The reactivity of the nuclear reactor is controlled by inserting it into and removing it from the chamber 29 (normal drive). Also,
Since it is necessary to rapidly insert the control rod 31 into the core 29 in an emergency, the control rod 31 is urgently inserted into the core 29 by the high pressure water supplied from the control rod drive device 35 through the scrum insertion pipe 9. To do.

In the conventional control rod drive device 35, as shown in FIG. 4, the condensate water supplied from the condensate water supply system (not shown) is boosted by the pump 1 to the filling water system 3 via the main pipe 2. It is distributed to the purge water system 4. The high-pressure condensate supplied to the filling water system 3 is distributed via the filling water header 5 to the plurality of water pressure control units 7 connected to the plurality of control rod drive mechanisms 6. The distributed condensate is supplied to the scrum insertion pipe 9 a and the accumulator 10 via the filling water check valve 15. The logic circuit 26a opens the scrum valve 11 which is closed during normal operation of the nuclear reactor in an emergency, and supplies the high-pressure condensate accumulated in the accumulator 10 to the control rod drive mechanism 6 via the scram insertion pipe 9.

In the above structure, when the supply of high-pressure condensate is cut off for some reason such as failure or stop of the pump 1 and the water pressure of the filling water system 3 drops for a long time, the control rod drive mechanism 6 To insert all the control rods 31 into the core 29 before the emergency insertion drive pressure is lost, the logic circuit 26a is used.
Controlled to open all the scrum valves 11. That is, the logic circuit 26a takes in the filling water pressure signal 25 obtained by measuring the water pressure at the pressure measuring point 20 of the filling water system 3, and when all the scram valves 11 have the water pressure reduced to a predetermined pressure or less. The scram signal 19 was transmitted and all the control rods 31 were urgently inserted into the core 29.

[0006]

SUMMARY OF THE INVENTION In the above conventional configuration,
Even if the pump 1 is stopped or the water pressure of the filling water system 3 is lowered for some reason in a range where there is no problem in plant operation, the emergency stop of all the control rods 31 into the core 29 is executed and the plant stops. Therefore, there is a problem that the plant operating rate is unnecessarily lowered.

An object of the present invention is to provide a control rod drive device capable of increasing the operating rate of a plant.

[0008]

In order to achieve the above object, the present invention provides a plurality of control rod drive mechanisms for driving a plurality of control rods and high-pressure water for driving the control rod drive mechanisms. In a control rod drive device comprising: a plurality of first water supply systems, and a second water supply system that is connected to the plurality of first water supply systems via distribution means and supplies the high-pressure water, The first water supply system is connected to a first pipe connected to the control rod drive mechanism, a second pipe connected to the distribution means, and a second pipe via a check valve. And a high pressure gas supply for supplying a high pressure gas for pumping the high pressure water in the third pipe to the first pipe, and a third pipe connected to the first pipe via an automatic opening / closing valve. And a system
Of the first pressure measuring means for measuring the gas pressure of the high-pressure gas supply system, the second pressure measuring means for measuring the water pressure of the second water supply system, and the first and second pressure measuring means. And a control means for controlling the opening / closing of the automatic opening / closing valve based on the output.

[0009]

According to the above means, the control means controls the opening / closing of the automatic opening / closing valve on the basis of the outputs of the first and second pressure measuring means, whereby the first water supply system is judged to be scrammed. The scrum signal is issued only to the automatic open / close valve of
Only the control rod corresponding to the first water supply system can be urgently inserted. Therefore, it is possible to prevent the urgent insertion of all the control rods into the core, which is unnecessary for plant operation, so that the plant operating rate can be increased.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A control rod drive device according to a first embodiment of the present invention will be described with reference to FIG. This device includes a plurality of control rod drive mechanisms that drive a plurality of control rods 6, a plurality of first water supply systems that supply high-pressure water that drives the control rod drive mechanisms, and a plurality of first water supplies. High pressure from the second water supply system and the first water supply system, which are connected to the supply system via high-pressure water distribution means (filling water header 5 and purge water header 17) and supply high-pressure water, to the control rod drive mechanism 6. It is composed of a logic circuit 26 for controlling the supply of water.

The first water supply system includes a scrum insertion pipe 9 connected to the control rod drive mechanism 6, a filling water pipe 8 connected to the filling water header 5, and a filling water pipe 8 via a check valve 15. A scrum valve (automatic valve) 1 connected to the scrum insertion pipe 9
1, a high-pressure nitrogen gas supply system (nitrogen gas pipe 12, nitrogen cylinder 13) for supplying high-pressure nitrogen gas for pumping high-pressure water in the scrum insertion pipe 9a and the scrum insertion pipe 9a ) Etc.

In the second water supply system, the condensed water supplied from the condensate water supply system (not shown) is boosted by the pump 1,
It is distributed to the filling water system 3 and the purging water system 4 through the main pipe 2. The high-pressure condensate supplied to the filling water system 3 is distributed to the plurality of water pressure control units 7 connected to the plurality of control rod drive mechanisms 6 via the filling water system check valve 14 and the filling water header 5. The distributed condensate is filled with the filling water pipe 8 and the filling water check valve 1
5, the scrum insertion pipe 9a and the accumulator 1
0 is supplied.

During normal operation of the nuclear reactor, the scrum valve 11
The piston 1 inside the accumulator 10 is pushed up by the nitrogen gas that has been pre-filled because it is closed.
0A is pushed down by the high-pressure condensate, and further compresses and stores the nitrogen gas in the nitrogen cylinder 13 connected through the nitrogen gas pipe 12. And in an emergency, the scrum valve 11
Open, the scrum insertion pipe 9a and the accumulator 10
The high-pressure condensate accumulated inside is supplied to the control rod drive mechanism 6 via the scrum insertion pipe 9. Fill water system check valve 14
And 15 temporarily hold the respective pressures of the filling water system 3 and the accumulator 10 when the pressures of the main pipe 2 and the filling water system 3 decrease.

The control rod drive mechanism 6 of FIG. 1 has a structure as shown in FIG. FIG. 6 is a vertical sectional view of the control rod drive mechanism 6,
The motor 34 performs the insertion / extraction drive of the control rod 31 during the normal drive by the control rod drive mechanism 6. That is,
When the drive shaft 36 is rotated by the motor 34, its rotational force is transmitted via the spline coupling 37 to the ball screw 38.
And the rotational movement of the ball screw 38 is converted into the up-and-down movement of the ball nut 39. Since the hollow piston 40 and the control rod 31 also move up and down together with the ball nut 39, the core 2 of the control rod 31 changes depending on the rotation direction of the motor 34.
9 can be inserted into or removed from the core 29.

Scrum operation in an emergency (control rod 31
Emergency full insertion) is performed by supplying high-pressure scrum water from the control rod drive device 35 through the scrum insertion pipe 9. That is, the scrum water supplied from the control rod drive device 35 flows into the inner cylinder 41 and pushes up the hollow piston 40. As a result, the hollow piston 40 separates from the ball nut 39 and rises integrally with the control rod 31, and the control rod 3
1 is fully inserted into the core 29.

The flow rate of the condensate supplied to the purge water system 4 is adjusted by the flow rate control valve 16 and is distributed via the purge water header 17 to the plurality of water pressure control units 7 connected to the plurality of control rod drive mechanisms 6. Condensed water distributed is purge water check valve 1
It is supplied to the scrum insertion pipe 9 on the downstream side of the scrum valve 11 via 8. Scrum insertion pipe 9 during normal operation
The condensate supplied to the control rod drive mechanism 6 is used as purge water for preventing sedimentation of clad and the like in the control rod drive mechanism 6. Further, in an emergency, the water pressure on the side of the scrum insertion pipe 9 becomes high, so the purge water check valve 18 is closed to prevent the back flow of scrum water to the purge water system 4.

Next, the control contents of the logic circuit 26 will be described. The logic circuit 26 includes a main pipe pressure signal 24 measured by a pressure measuring means such as a pressure gauge at a pressure measuring point 22 provided on the main pipe 2 and a pressure gauge at a pressure measuring point 21 provided on the nitrogen gas pipe 12. The nitrogen gas pressure signal 23 measured in 1 is taken in, and the scrum signal 19 is transmitted to each water pressure control unit according to the combination of each signal. That is, the scram signal 19 for emergency insertion is issued only to the hydraulic control unit that is determined to require emergency insertion, and the control rod corresponding to the hydraulic control unit is emergency inserted.

For example, when both the main pipe pressure signal 24 and the nitrogen gas pressure signal 23 are below the threshold values set respectively, and the state continues for a predetermined time (indicated by a circle in Table 1), A scrum signal 19 is issued to the scrum valve 11 of the water pressure control unit 7 that has output the nitrogen gas pressure signal 23. In this way, the control rod 31 corresponding to the hydraulic control unit 7 which has issued the scrum signal 19 is urgently inserted, and an alarm is issued to notify that the control rod 31 has been urgently inserted.

[0019]

[Table 1]

When the pressure signal of either the main pipe pressure signal 24 or the nitrogen gas pressure signal 23 falls below the threshold value set for each of them and the state continues for a predetermined time (marked by Δ in Table 1). In the case (1)), an alarm is issued to notify that the main pipe pressure or the nitrogen gas pressure has dropped.
In this case, the scrum signal 19 is not emitted. Furthermore, when the main pipe pressure signal 24 and the nitrogen gas pressure signal 23 are both higher than the threshold values set for each (Table 1
(Indicated by X), the control rod drive device 35 is in a healthy state, and thus the plant operation is continued.

According to this embodiment, the logic circuit 26 controls the opening / closing of the scrum valve 11 based on the outputs of the main pipe pressure signal 24 and the nitrogen gas pressure signal 23, thereby controlling the water pressure which is judged to be scram. Since only the control rod 31 corresponding to the unit 7 can be urgently inserted, urgent insertion of all the control rods, which is unnecessary for plant operation, into the core can be prevented, and the plant operating rate can be increased.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a view showing a control rod drive device according to a second embodiment of the present invention, and the same parts as those in FIG. In this embodiment, the main pipe pressure signal 24 of the first embodiment is used.
The difference is that the filling water pressure signal 25 of the filling water system 3 is used instead of the above, and the other configurations are the same as those in the first embodiment, and therefore the description thereof is omitted here.

The logic circuit 26 of this embodiment has a filling water pressure signal 25 measured by a pressure gauge at a pressure measuring point 20 provided on a pipe between the check valve 14 of the filling water system 3 and the filling water header 5.
And a nitrogen gas pressure signal 23 measured by a pressure gauge at a pressure measuring point 21 provided on the nitrogen gas pipe 12, and a scrum signal 19 is transmitted to each water pressure control unit 7 according to a combination of the signals. Similar to the first embodiment, the scram signal 19 for emergency insertion is issued only to the hydraulic control unit determined to require emergency insertion, and the control rod 31 corresponding to the hydraulic control unit is emergency inserted.

In the logic circuit 26, the magnitude relation between the filling water pressure signal 25 and the nitrogen gas pressure signal 23 and the respective threshold values is compared, and the scram valve 11 is determined according to the relation, as in the first embodiment. Open and close control. Scrum signal 1
9 and the conditions for issuing an alarm are different in the three cases indicated by ○, △, and × in Table 2, and the logic circuit 26 in each case is different.
The control content of is the same as that of the first embodiment.

[0025]

[Table 2]

In this embodiment, since the pressure measuring point 20 is located downstream of the check valve 14 for the filling water system, even if the pump 1 is stopped for some reason, the side of the filling water system 3 is closer to the main pipe 2.
Since the water pressure is higher than that on the side, the filling water system check valve 14 is closed and the water pressures in the filling water pipe 8 and the filling water system 3 can be maintained for a long time. Therefore, it can be confirmed that the filling water system 3 maintains the emergency insertion drive pressure of the control rod drive mechanism 6 even when the pump 1 is stopped, and unnecessary plant stop can be avoided and the plant operating rate can be increased.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a view showing a control rod drive device according to a third embodiment of the present invention, and the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals. In this embodiment, pressure measuring means is provided on the main pipe 2 by providing pressure measuring means on the main pipe 2, on the pipe between the check valve 14 of the filling water system 3 and the filling water header 5, and on the nitrogen gas pipe 12. Main pipe pressure signal 24 measured at point 22, fill water pressure signal 25 measured at pressure measurement point 20 provided on filling water system 3, and pressure measurement point 21 provided on nitrogen gas pipe 12 The nitrogen gas pressure signal 23 and the logic circuit 2
6, the logic circuit 26 sends the scrum signal 1 to each water pressure control unit 7 according to the combination of the respective signals.
9 is transmitted. The rest of the configuration is the same as that of the first embodiment, so its explanation is omitted here. Also in the present embodiment, as in the first embodiment, the scram signal 19 for emergency insertion is issued only to the scram valve 11 of the water pressure control unit 7 which is determined to require emergency insertion, and the water pressure control unit is generated. The control rod 31 corresponding to No. 7 is urgently inserted.

The logic circuit 26 of this embodiment includes a main pipe pressure signal 24, a filling water pressure signal 25, and a nitrogen gas pressure signal 2.
3 is taken in and the combination of the main pipe pressure signal 24 and the nitrogen gas pressure signal 23 is judged in the same manner as in the first embodiment,
The combination of the filling water pressure signal 25 and the nitrogen gas pressure signal 23 is determined in the same manner as in the second embodiment, and the opening / closing control of the scrum valve 11 is performed based on these two determination results. As a result of the judgment, there are three cases indicated by ◯, Δ, and X as described above, and judgment is made for each of the two combinations (see Table 3).

[0029]

[Table 3]

Regarding the control for opening the scrum valve 11,
The mark has the highest priority, and the marks have a lower priority in the order of Δ and X. Therefore, if the judgment results of the two combinations are the same, the logic circuit 26 performs control according to the judgment results, and
When the judgment results of the two combinations are different, the control is performed according to the judgment result of the higher priority.

In this embodiment, the water pressure drop can be detected more reliably by multiplexing the water pressure measurement points.
As in the first and second embodiments, unnecessary plant stoppages can be avoided and the plant operating rate can be increased.

[0032]

EFFECTS OF THE INVENTION According to the present invention, even if the pump for supplying high-pressure water is stopped or the water pressure of the filling water system is lowered for some reason within a range where there is no problem in plant operation, the plant is unnecessary. Since it is possible to avoid the stop of the plant, it is possible to increase the plant operating rate.

[Brief description of drawings]

FIG. 1 is a diagram showing a control rod drive device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a control rod drive device according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a control rod drive device according to a third embodiment of the present invention.

FIG. 4 is a view showing a conventional control rod drive device.

FIG. 5 is a vertical cross-sectional view around the core of a conventional boiling water reactor.

FIG. 6 is a vertical cross-sectional view of the control rod drive mechanism according to the first embodiment.

[Explanation of symbols]

1 ... Pump, 2 ... Main piping, 3 ... Filled water system, 5 ... Filled water header, 6 ... Control rod drive mechanism, 7 ... Water pressure control unit, 8
… Filling water piping, 9… Scrum insertion piping, 10… Accumulator, 11… Scrum valve, 12… Nitrogen gas piping, 19
... Scrum signal, 20 ... Pressure measurement point, 21, 22 ... Pressure measurement point, 23 ... Nitrogen gas pressure signal, 24 ... Main pipe pressure signal, 25 ... Fill water pressure signal, 26 ... Logic circuit, 27 ... Reactor pressure vessel , 31 ... control rod, 34 ... motor, 35 ... control rod drive device.

Claims (4)

[Claims] 1. A plurality of control rod drive mechanisms for driving a plurality of control rods, a plurality of first water supply systems for supplying high-pressure water for driving the control rod drive mechanisms, and a plurality of the first plurality of water supply systems. A second water supply system which is connected to the water supply system of FIG. 1 through a distribution means and supplies the high-pressure water, wherein the first water supply system is connected to the control rod drive mechanism. A first pipe, a second pipe connected to the distributing means, a second pipe connected to the second pipe via a check valve, and a first pipe connected to the first pipe via an automatic opening / closing valve. A third pipe and a high-pressure gas supply system for supplying high-pressure gas for pumping the high-pressure water in the third pipe to the first pipe are provided, and the gas pressure of the high-pressure gas supply system is further provided. First pressure measuring means for measuring, second pressure measuring means for measuring water pressure of the second water supply system, and Control rod drive, characterized in that a control means for controlling the opening and closing of the automatic opening and closing valve on the basis of the output of the first and second pressure measuring means. 2. The high pressure system according to claim 1, wherein the second water supply system is connected to a fourth pipe connected to the distribution means, and is connected to the fourth pipe via a check valve. A fifth pipe having a pump for increasing the pressure of water, wherein the second pressure measuring means is connected between the pump and the check valve in the fifth pipe. Rod drive. 3. The high-pressure water supply system according to claim 1, wherein the second water supply system is connected to a fourth pipe connected to the distribution means, and is connected to the fourth pipe via a check valve. A fifth pipe having a pump for increasing the pressure of water, wherein the second pressure measuring means is connected to the fourth pipe. 4. The high-pressure system according to claim 1, wherein the second water supply system is connected to a fourth pipe connected to the distribution means, and is connected to the fourth pipe via a check valve. A second pipe having a pump for increasing the pressure of water, wherein the second pressure measuring unit is a pressure measuring unit connected to the fourth pipe, and the pump and the reverse of the fifth pipe. A control rod drive device comprising: a pressure measuring means connected between the stop valves.