Fine motion control rod drive mechanism handling apparatus and method of handling fine motion control rod drive mechanism

A fine motion control rod drive mechanism handling apparatus attaches a fine motion control rod drive mechanism having a control rod drive mechanism body, a spool piece, a motor bracket and a motor unit to a reactor pressure vessel, and detaches it from the reactor pressure vessel. The fine motion control rod drive mechanism handling apparatus is provided with a bolt wrench assembly, a motor unit attachment mounted to the bolt wrench assembly, for meshing a first gear of a first gear coupling on a spool piece side with a second gear of a second gear coupling on a motor unit side, and a rotation mechanism mounted to the bolt wrench assembly, for rotating the motor unit attachment.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent application serial no. 2010-80068, filed on Mar. 31, 2010, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a fine motion control rod drive mechanism handling apparatus and a method of handling a fine motion control rod drive mechanism for attaching and detaching a fine motion control rod drive mechanism.

2. Background Art

A fine motion control rod drive mechanism is provided with four kinds of components of a control rod drive mechanism body, a spool piece, a motor bracket, and a motor unit. The fine motion control rod drive mechanism is attached to and detached from control rod drive mechanism housings installed side by side crosswise at a pitch of about 300 mm at the bottom of a reactor pressure vessel by a fine motion control rod drive mechanism handling apparatus.

In Japanese Patent Laid-open No. 2000-329892, an attaching and detaching attachment of the motor unit being used in the fine motion control rod drive mechanism is described. The motor unit attachment for fitting phase of a flange of the motor unit to phase of a flange of a motor bracket and for executing fine adjustment of the attaching position of the motor unit by using a rotational position adjusting means when attaching the motor unit is described.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

Technical Problem

However, in the prior art described in Japanese Patent Laid-open No. 2000-329892, there exists the following problem. Conventionally, when attaching the motor unit to the motor bracket, it is necessary to mesh outer teeth of a gear coupling on the motor unit side with inner teeth of a gear coupling on the spool piece side in the tip-root position of the gear. When the gear coupling on the motor unit side is not meshed with the gear coupling on the spool piece side in the tip-root position phase of the gear, the leading edge faces of the gear couplings make contact with each other, thereby not meshing with each other, thus a bolt wrench assembly of the fine motion control rod drive mechanism handling apparatus cannot ascend and the motor unit cannot be attached to the motor bracket. Therefore, it becomes necessary to descend the bolt wrench assembly, adjust a rotational position at the tip-root position of the gear of the gear coupling on the motor unit side by visually confirming the tip-root position of the gear of the motor unit so as to mesh with the tip-root position of the gear of the gear coupling on the spool piece side, ascend the bolt wrench assembly again, and repeatedly execute the attaching operation of the motor unit to the motor bracket.

An object of the present invention is to provide a fine motion control rod drive mechanism handling apparatus and a method of handling a fine motion control rod drive mechanism capable of improving operability for attaching a motor unit and of shortening the attaching operation time.

Solution to Problem

The present invention for accomplishing the above object is characterized in that in a fine motion control rod drive mechanism handling apparatus provided with a motor unit attachment for attaching a motor unit of a fine motion control rod drive mechanism to a motor bracket, the fine motion control rod drive mechanism handling apparatus has a rotational mechanism for rotating the motor unit and a spring mechanism for pressing the motor unit to the bracket.

Advantageous Effect of the Invention

According to the present invention, the attaching operation time of the motor unit can be shortened.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, each embodiment will be explained with reference to drawings.

(Explanation of the Fine Motion Control Rod Drive Mechanism)

FIG. 4is a longitudinal sectional view showing an overall schematic structure of a fine motion control rod drive mechanism16to which a fine motion control rod drive mechanism handling apparatus is applied. InFIG. 4, the fine motion control rod drive mechanism16is provided with a control rod drive mechanism body13having a mechanism for moving up and down a control rod18disposed in a reactor pressure vessel100and a rotary shaft20, a spool piece14having a magnet coupling23for transmitting the turning force by magnetic force via the pressure resistant portion joined to the rotary shaft20, a motor unit7having a built-in motor as a drive source, and a motor bracket15for connecting the motor unit7and spool piece14. The control rod drive mechanism body13is disposed in a control rod drive mechanism housing12connected to a bottom head portion of the reactor pressure vessel100.

FIG. 2is an explanatory drawing showing a preparation state of operation for attaching a motor unit by using a fine motion control rod drive mechanism handling apparatus. The fine motion control rod drive mechanism16has four kinds of components of the control rod drive mechanism body13, spool piece14, motor bracket15, and motor unit7. The components thereof are each attached to and detached from the control rod drive mechanism housings installed side by side crosswise at a pitch of about 300 mm at the bottom head portion of the reactor pressure vessel by using the fine motion control rod drive mechanism handling apparatus. The fine motion control rod drive mechanism handling apparatus has four kinds of attachments of a control rod drive mechanism body attachment, a spool piece attachment, a motor bracket attachment, and a motor unit attachment in correspondence with the four kinds of components composing the fine motion control rod drive mechanism16. The attachment attached to a head portion of the bolt wrench assembly11of the fine motion control rod drive mechanism handling apparatus is changed one of the above four attachment depending on the target component of the fine motion control rod drive mechanism for executing attaching and detaching, thus each device can be attached and detached.

FIG. 3is an explanatory drawing showing operation for attaching a motor unit, using a fine motion control rod drive mechanism handling apparatus. A motor unit attachment6is attached to the attachment of the head portion of the bolt wrench assembly11. The bolt wrench assembly11is ascended by the fine motion control rod drive mechanism handling apparatus, and then the motor unit7is attached to the motor bracket15with an attaching bolt17.

Further, the fine motion control rod drive mechanism16, in which the control rod drive mechanism body13, spool piece14, motor bracket15, and motor unit7are each bolt-joined, is provided with a rotary shafts19and20. The rotary shaft19transmits drive force from the motor unit which is a rotation drive source to the magnet coupling23via a gear coupling8on the motor unit side and a gear coupling21on the spool piece side. The rotary shaft20transmits the drive force from the magnet coupling23to the mechanism for driving the control rod so as to ascend in the pressure partition. To hold the control rod, the brake in the motor unit7is used. When the motor unit7is removed from the motor bracket15, the rotary shaft20rotates in a withdrawal direction of the control rod18. To prevent rotation of the rotary shaft20and gear coupling21of the spool piece14, a rotation stopping mechanism (not shown) is installed in the spool piece14. Also in the motor bracket15, a rotation stopping mechanism22is installed.

(Explanation of the Motor Unit Attachment)

FIG. 1is a longitudinal sectional view showing a fine motion control rod drive mechanism handling apparatus according to present embodiment and shows a state that the motor unit7is put on the motor unit attachment6of the fine motion control rod drive mechanism handling apparatus. InFIG. 1, the motor unit attachment6has mainly a bracket1for putting the motor unit7on, a spring mechanism2(an elasticity portion) as an elasticity member for relieving the load when the bracket1is pressed, a casing3for supporting an entire device including the motor unit7, and a shaft5having a connection portion connected to the bolt wrench assembly11. The bracket1of the motor unit attachment6includes a bolt wrench27for tightening an attaching bolt17for attaching the motor unit7to the motor bracket15and a positioning pin4for positioning the motor unit7in the rotational direction. Further, the motor unit attachment6operates in accordance with the operation of the bolt wrench assembly11of the fine motion control rod drive mechanism handling apparatus that rotates at a specified angle. In addition, the motor unit attachment6has a load meter10for measuring the load and a limit switch9for detecting the movement limit.

(Explanation of the Motor Unit Attaching Operation of the Fine Motion Control Rod Drive Mechanism)

Next, the operation of attaching the motor unit7of the fine motion control rod drive mechanism16will be explained.

As shown inFIG. 2, the motor unit attachment6is attached to the bolt wrench assembly11at the head portion of the fine motion control rod drive mechanism handling apparatus. The bolt wrench assembly11where the motor unit attachment6is already attached is positioned to a position for attaching the motor unit7. After positioning, the motor unit7being an attaching object is put on the motor unit attachment6attached to the bolt wrench assembly11.

As shown inFIG. 3, the bolt wrench assembly11is ascended and the motor unit7is mounted to the motor bracket15attached to the spool piece14fixed to the control rod drive mechanism housing12, by the bolt wrench assembly11. When the bolt wrench assembly11ascends, the outer teeth of the gear coupling8of the motor unit7and the inner teeth of the gear coupling21of the spool piece14mesh with each other, and the bolt wrench assembly11ascends straight, thus the motor unit7is pressed in, and the motor unit7is mounted to the motor bracket15. After mounting the motor unit7, the attaching bolt17of the motor unit7is tightened by the bolt wrench27of the motor unit attachment6, and the motor unit7is attached to the motor bracket15. After attaching the motor unit7, if the bolt wrench assembly11with the motor unit attachment6attached to it is descended, the motor unit7and the motor unit attachment6are separated from each other. Furthermore, the bolt wrench assembly11is descended, and the motor unit attachment6is detached from the bolt wrench assembly11, thus the attaching operation of the motor unit7is finished.

(Explanation of the Motor Unit Detaching Operation of the Fine Motion Control Rod Drive Mechanism)

Next, the operation of detaching the motor unit7of the fine motion control rod drive mechanism16will be explained. The position of the bolt wrench assembly11of the fine motion control rod drive mechanism handling apparatus is positioned to the motor unit a position of the motor unit11being a detaching object mounted to the motor bracket15. The motor unit attachment6is attached to the bolt wrench assembly11, and the bolt wrench assembly11with the motor unit attachment6attached to it is ascended, and the motor unit attachment6is mounted to the motor unit7to be detached. After mounting the motor unit attachment6, the attaching bolt17of the motor unit7is loosened by the bolt wrench27of the motor unit attachment6, and the motor unit7is detached from the motor bracket15. The detached motor unit7is put on the top of the motor unit attachment7and if the bolt wrench assembly11is descended, it is separated from the motor bracket. The bolt wrench assembly11is descended furthermore, and the motor unit7is taken out from the motor unit attachment6. The motor unit attachment6is detached from the bolt wrench assembly11, thus the motor unit detaching operation is finished.

A method for attaching the motor unit7in the embodiment 1 by using the fine motion control rod drive mechanism handling apparatus will be explained with reference toFIGS. 5 and 6.FIG. 5shows a flowchart of operation procedure for attaching a motor unit7andFIG. 6shows specific contents of processes shown inFIG. 5. A case that the gear coupling8on the motor unit side shown inFIG. 5and the gear coupling21on the spool piece side do not coincide with each other in the tip-root phase of the gear will be described below.

The motor unit7is attached to the motor unit attachment6(step S1). After that, the motor unit7is ascended (step S2).FIG. 6(a) shows a state where the motor unit attachment6is attached to the bolt wrench assembly11of the fine motion control rod drive mechanism handling apparatus, and the bolt wrench assembly11has been ascended with the motor unit attachment6on which the motor unit7is put. The ascent and descent is executed by a mechanism for ascending and descending the bolt wrench assembly11by a motor drive. The mechanism for ascending and descending the bolt wrench assembly11is attached to the fine motion control rod drive mechanism handling apparatus. The bolt wrench assembly11is positioned to the specified attaching position of the motor unit7, and then the motor unit7is ascended. At this time, the motor unit attachment6and motor unit7are ascended in a state where they have been rotated by a specified angle on the axis relative to the bolt joint position to the motor bracket15. In this rotation, the motor unit attachment6and motor unit7can be rotated by a rotational mechanism installed on the bolt wrench assembly11. As an example of the rotational mechanism, a motor may be cited. Further, the motor unit7is attached in accordance with the positioning pin4in the rotational direction of the motor unit attachment6, thus the position in the rotational direction is not changed.

Whether the tip-root phase of the gear of the gear coupling8on the motor unit side and the tip-root phase of the gear of the gear coupling21on the spool piece side coincide with each other or not is determined (step S3). When this determination is “YES”, that is, these tip-root phases coincide with each other; operation of step S7is executed. The operation of the steps S7and S8will be described later. When that determination is “No”, that is, these tip-root phases do not coincide with each other; operation of step S4is executed. The motor unit7is ascended (step S4).FIG. 6(b) shows a state that the motor unit attachment6, and the bolt wrench assembly11with the motor unit7attached are ascended and end faces of the gear coupling8and the gear coupling21are in contact with each other.

Outer teeth84of the gear coupling8on the motor unit side and inner teeth82of the gear coupling21on the spool piece side are shaped as shown inFIGS. 7(a) and7(b). When the motor unit7ascends, if the outer teeth84of the gear coupling8on the motor unit side and the inner teeth82of the gear coupling21on the spool piece side do not mesh with each other in the tip-root position of the gear, a tip end of the gear coupling8on the motor unit side come into contact with an end face of the gear coupling21on the spool piece side. Further, when the outer teeth84and inner teeth82do not mesh with each other in the tip-root position of the gear, the tip-root positions of both gears may be detected based on the information from the sensor for detecting the respective rotational angles of the outer teeth84of the gear coupling8on the motor unit side and the inner teeth82of the gear coupling21on the spool piece side and the design data of the respective gears. And, the procedures shown inFIG. 6(c) and the subsequent drawings may be executed so as to phase-focus the shifted positions using the detected positions.

In a state that the end faces of the gear couplings come into contact with each other, the bolt wrench assembly11is ascended furthermore, so that to prevent the gear couplings from application of an excessive load, the spring mechanism2built in the motor bracket15of the motor unit attachment6is contracted. Consequently, in the motor unit attachment6, a state that a pressing load is acted upward by the spring reaction force is kept. The gear coupling8on the motor unit side and internal parts can be prevented from damage because excessive load is not added to the gear couplings by the spring mechanism. Furthermore, the bolt wrench assembly11is ascended, so that the position of the motor unit7is not changed. However, the spring mechanism2is compressed. The movement amount of the bolt wrench assembly11is detected by the position detector installed in the bolt wrench assembly11, and the bolt wrench assembly11is stopped at a preset position. The position detector measures the movement amount by the position detector for detecting the rotational angle of the motor on the side of the fine motion control rod drive mechanism handling apparatus. At this time, the ascending height of the bolt wrench assembly11should be such that the attaching faces of the motor unit7and motor bracket15are within the range free of contact with each other when the outer teeth of the gear coupling8on the motor unit side and the inner teeth of the gear coupling21on the spool piece side mesh with each other in the tip and root of the gear and the gear coupling8on the motor unit side is inserted in the gear coupling21on the spool piece side. One reason of setting the attaching faces of the motor unit7and motor bracket15within the range free of contact with each other is that if the motor unit7is lifted up beyond the range in which the motor unit7come into contact with the motor bracket15, when the motor unit7is rotated by the next operation and the gears coincide with each other in the phase, the motor unit7is lifted up by an upward pressing load of the spring mechanism2and the motor unit7collides with the motor bracket15and is damaged, so that the damage of the motor unit7and motor bracket15must be prevented, and the other is that, if the faces of the motor unit7and motor bracket15make contact with each other after the gears coincide with each other in the phase during rotation, the rotation that must be performed before the bolt joint position comes up becomes impossible, so this must be prevented. In addition, to detect that the end faces of the gear coupling8on the motor unit side and the gear coupling21on the spool piece side make contact with each other, when the spring mechanism2of the motor unit attachment6is contracted and the bracket1descends, a limit switch9installed in the motor unit attachment6can detect it. When the limit switch9detects the descent of the bracket1, the ascent of the motor unit7is stopped. Further, when the end faces of the gear coupling8on the motor unit side and the gear coupling21on the spool piece side make contact with each other and the upward pressing load acts on the bracket1of the motor unit attachment6, the upward pressing load can be confirmed by an increase of a measurement value measured by the load meter10installed at the lower end of the motor unit attachment6.

After the end faces of the gear coupling8on the motor unit side and the gear coupling21on the spool piece side made contact with each other and the ascent of the motor unit7was stopped, the motor unit7attached to the bolt wrench assembly11is rotated (step S5).FIG. 6(c) shows a state that the bolt wrench assembly11has been rotated in the state shown inFIG. 6(b) and the motor unit attachment6and motor unit7have been rotated together. When the upward pressing force by the spring mechanism2built in the motor unit attachment6is acted on the bracket1, the bolt wrench assembly11rotates the motor unit attachment6and motor unit7. Consequently, between the gear coupling21on the spool piece side and the gear coupling8on the motor unit side, the gear coupling8on the motor unit side rotates relatively. In this rotation, the gear coupling8on the motor unit side is rotated by the motor (not shown) installed on the bolt wrench assembly11of the fine motion control rod drive mechanism handling apparatus. At this time, in the motor unit7, the upward pressing force of the spring mechanism2built in the motor unit attachment6is generated, and the spring force of the spring mechanism2built in the motor unit attachment6is set so that upward pressing force smaller than the resistance due to the sliding friction during relative rotation will be obtained in the state that the end faces of the gear coupling8on the motor unit side and the gear coupling21on the spool piece side make contact with each other.

The motor unit7is inserted into the motor bracket15(step S6).FIG. 6(d) shows a state that the motor unit attachment6and motor unit7were rotated in the state shown inFIG. 6(c), and the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincided with each other in the tip-root phase of the gear, and the bracket1and motor unit7were pressed up by the upward pressing force of the spring mechanism2built in the motor unit attachment6, and the gear coupling8on the motor unit side has been inserted into the gear coupling21on the spool piece side, thus the gears of the gear couplings8and21have meshed with each other. At this time, that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side have coincided with each other in the tip-root phase of the gear, can be detected by the limit switch9installed in the motor unit attachment6because the bracket1of the motor unit attachment6is lifted up by the upward pressing force of the spring mechanism2. Furthermore, since the value of the load meter10installed at the lower end of the motor unit attachment6is reduced by the release from the upward pressing force of the spring mechanism2, it can be confirmed that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side have coincided with each other in the tip-root phase of the gear. Additionally, as for a rotational angle of the motor unit7, the motor unit7has been ascended in a state that the motor unit7has firstly rotated by a specified angle relative to the bolt joint positions to the motor unit7and motor bracket15. When the rotation is finished, the bolt joint positions to the motor unit7and motor bracket15coincide with each other.

Further, the rotation of the motor unit7is started, and after the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear during the rotation and the gear coupling8on the motor unit side is inserted into the gear coupling21on the spool piece side, the rotation of the motor unit7is continued. The motor unit7is rotated continuously in the state that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side are meshing with each other in the gear. The rotation is stopped at the bolt joint position of the motor unit7and motor bracket15.

The bolt wrench assembly11is ascended (step S9).FIG. 6(e) shows a state that in the state that as shown inFIG. 6(d), the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear and the gears are meshing with each other, the bolt wrench assembly11has been ascended furthermore, and the motor unit7and motor bracket15are in contact with each other. When ascending the bolt wrench assembly11, the bolt wrench assembly11is pressed up furthermore to confirm that the motor unit7come into contact with the motor bracket15, and the spring mechanism2built in the motor unit attachment6is further compressed, and the bracket1is pressed down. It can be detected that the bracket1has come into contact with the motor bracket15by the limit switch9installed in the motor unit attachment6. Further, if the motor unit7has come into contact with the motor bracket15, the measurement value of the load meter10installed at the lower end of the motor unit attachment6also increases. That the motor unit7has come into contact with the motor bracket15can be simultaneously confirmed by the limit switch9and load meter10. It is confirmed that the motor unit7come into contact with the motor bracket15based on the position detection and load detection and the ascent of the bolt wrench assembly11is stopped. Further, when the bolt wrench assembly11ascends and the motor unit7is inserted into the motor bracket15, the motor unit7corrects the position shifts in the horizontal direction by the spigot joint of the motor unit7and the positioning pin4and rotational direction of the motor bracket15. Thus, the motor unit7is positioned.

The motor unit7is attached to the motor bracket15(step S10),FIG. 6(f) shows the state that after the motor unit7and motor bracket15are positioned inFIG. 6(d), the bolt wrench27installed on the motor unit attachment6comes out and tightens the motor unit attaching bolt17, and the motor unit7is attached to the motor bracket15.

The motor unit attachment6is withdrawn from the motor unit7(step S11).FIG. 6(g) shows a state that the motor unit7is attached to the motor bracket15, and the attached bolt wrench assembly11to which the motor unit attachment6was attached has descended, and the motor unit attachment6has been pulled out from the motor unit7. Since the motor unit attachment6is withdrawn from the motor unit7, the bracket1of the motor unit attachment6is lifted up by the upward pressing force of the spring mechanism2. It can be confirmed that the motor unit attachment6has been withdrawn from the motor unit7by the change in the limit switch9installed on the motor unit attachment6and the reduction in the measurement value of the load meter10installed at the lower end of the motor unit attachment6after the load of the motor unit7is released. After the motor unit attachment6was detached from the descended bolt wrench assembly11, the attaching operation of the motor unit7completes.

Next, When the determination of the step S3shown inFIG. 5is “YES”, that is, in the case that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear, operation procedure for attaching a motor unit7will describe with reference toFIGS. 5 and 8.

Similarly toFIG. 6(a),FIG. 8(a) shows the state where the bolt wrench assembly11is ascended with the motor unit7put on the motor unit attachment6.

The motor unit7is ascended (step S7).FIG. 8(b) shows a state that the motor unit attachment6and the bolt wrench assembly11with the motor unit7attached to is ascended and, since the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear, the outer teeth of the gear coupling8on the motor unit side are inserted into the inner teeth of the gear coupling21on the spool piece side and the gears are meshed with each other. Since the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear, the gear coupling8on the motor unit side is inserted into the gear coupling21by the ascent of the bolt wrench assembly11, and the bolt wrench assembly11ascends up to a specified height. As for the ascending height of the bolt wrench assembly11, similarly toFIG. 6(b), the movement amount of the bolt wrench assembly11is detected by the position detector installed on the bolt wrench assembly11. When it was detected by the position detector that the bolt wrench assembly11has ascended up to the specified height, the bolt wrench assembly is stopped at a preset position. Further, the confirmation of the consistency of the tip-root phase of the gear between the gear coupling8on the motor unit side and the gear coupling21on the spool piece side can be judged from that the bolt wrench assembly11reaches the specified height and the limit switch9installed on the motor unit attachment6and the load meter10installed at the lower end of the motor unit attachment6are not changed.

The motor unit7is rotated (step S8).FIG. 8(c) shows the state that inFIG. 8(b), that is, in the state that the teeth of the gear coupling8on the motor unit side and the gear coupling21on the spool piece side have been inserted and the gears are meshing with each other, the bolt wrench assembly11is rotated. The rotational angle, similarly toFIG. 6(d), is a set rotational angle. The state in which the operation of the step S8was finished is in the same state as the state in which the operation of the step S6was finished. As a consequence, processes for attaching the motor unit to the motor bracket15executed after step S8is the same as the processes of the steps S9-S11. Further, both procedures of the case that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side do not coincide with each other in the tip-root phase of the gear (the processes of the steps S1-S6and S9-S11) and the case that the phases coincide with each other (the processes of the steps S1-S3, S7,S8and S9-S11) are automated before the motor unit7is joined to the motor bracket15by the attaching bolt17. Further, it is possible to keep the procedures unautomated, confirm the limit switch operation and change in the load meter by a person at each step, and then go to the next step or to keep the procedures automated, confirm the limit switch operation and change in the load meter by a person at each step, and then go to the next step. In the automation processing, the processes of the steps S1-S11shown inFIG. 5are performed by a control apparatus. The control apparatus is a computer having a storage device such as a memory and a hard disk for receiving information from each sensor and recording the received data. The data measured by the sensors and transmitted from the sensors is received by the input/output section of the control apparatus and is subject to the processes of the steps S1-S11by the CPU of the control apparatus. Each process of the steps S1-S11is performed by loading and executing the program in the computer.

According to the use of the aforementioned fine motion control rod drive mechanism handling apparatus of the present embodiment, when the gear coupling8on the motor unit side and the gear coupling21on the spool piece side do not coincide with each other in the tip-root phase of the gear, the readjustment of the rotational position of the gear coupling8on the motor unit side is unnecessary and the retry operation is unnecessary. Consequently, a series of attaching operations are simplified and can be automated, and the attaching operability of the motor unit7is improved. By doing this, the time of the motor unit attaching operation can be shortened.

Further, the damage of the motor unit7at the time of attachment of the motor unit7and the damage of the rotation stopping mechanism22of the spool piece14can be prevented, so that a highly reliable control rod drive mechanism16can be provided.

A fine motion control rod drive mechanism handling apparatus according to embodiment 2, which is another embodiment of the present invention, will be described below with reference toFIG. 9. Assuming the state that the fine motion control rod drive mechanism handling apparatus can only ascend and descend (the rotational mechanism by which the bolt wrench assembly11is ascended does not operate or there is an interference article in the periphery, so that it cannot operate), the apparatus can respond to it by only rotating the motor unit7.

The attaching rotational position of the motor unit7when the bolt wrench assembly11is ascended in the state that the motor unit attachment6is attached to the bolt wrench assembly11of the fine motion control rod drive mechanism handling apparatus and the motor unit7is put on the motor unit attachment6, is different from the state shown inFIG. 6(a), and the motor unit attachment6and motor unit7is ascended at the rotational position which is the bolt joint position to the motor bracket15. After the ascent of the motor unit7, if the gear coupling8on the motor unit side and the gear coupling21on the spool piece side do not coincide with each other in the tip-root phase of the gear, similarly toFIG. 6(b), the bolt wrench assembly11with the motor unit attachment6and motor unit7attached to it is ascended, and the end face of the gear coupling8on the motor unit side comes into contact with the end face of the gear coupling21on the spool piece side, and the spring mechanism2built in the motor unit attachment6is compressed, and the state that a pressing load is acted upward by the spring reaction force is kept. Thereafter, similarly toFIG. 6(b), it is detected that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side have come into contact with each other by the change in the limit switch9and the increase in the load meter10.

FIG. 9shows a state that in the state that the end faces of the gear coupling8on the motor unit side and the gear coupling21on the spool piece side come in contact with each other and the upward pressing force is acted by the reaction force of the spring mechanism2built in the motor unit attachment6, the brake in the motor unit7is released by a brake release mechanism26and a counter-output shaft24of the motor unit7is being rotated.

After release of the brake of the motor unit7, a rotation lever25is attached to a counter-output shaft24of the motor unit7and a rotation lever is rotated. If the rotation lever is rotated, a drive shaft in the motor unit7that is connected to the counter-output shaft24of the motor unit7is rotated and the gear coupling8on the motor unit side is also rotated. If the gear coupling8on the motor unit side is rotated relatively between the gear coupling8on the motor unit side and the gear coupling21on the spool piece side, the gear coupling8on the motor unit side is inserted into the gear coupling21on the spool piece side at the position where the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear. At this time, since the change in the limit switch9installed on the motor unit attachment6and the reduction in the load meter10installed at the lower end of the motor unit attachment6are confirmed, it can be confirmed that the gear coupling8on the motor unit side and the gear coupling21on the spool piece side have coincided with each other in the tip-root phase of the gear and the gear coupling8on the motor unit side has been inserted into the gear coupling21. Furthermore, also after the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the tip-root phase of the gear, the rotation lever25is rotated at a fixed angle and thereafter, the brake of the motor unit7is released by the brake release mechanism26, and the drive shaft is restrained, and then the rotation lever25is detached from the counter-output shaft24of the motor unit7.

After the gear coupling8on the motor unit side and the gear coupling21on the spool piece side coincide with each other in the phase of the gear, the brake of the motor unit7is released, and the drive shaft is restrained, the processes of the steps S9-S11are executed. That is, the bolt wrench assembly11is ascended, and the motor unit7and motor bracket15are permitted to come into contact with each other. Additionally, the bolt wrench27installed on the motor unit attachment6comes out and tightens the motor unit attaching bolt. Thus, the motor unit7is attached to the motor bracket15. After that, the bolt wrench assembly11with the motor unit attachment6attached to it is descended, and the motor unit attachment6is withdrawn from the motor unit7.

A fine motion control rod drive mechanism handling apparatus according to embodiment 3, which is another embodiment of the present invention, will be described below with reference toFIG. 10.

The procedure for attaching the motor unit7is the same as the procedure of embodiment 1 shown inFIG. 5, thoughFIG. 10shows a state that using a displacement meter28installed on the motor unit attachment6instead of the limit switch9, the distance between the bracket1of the motor unit attachment6and the casing3can be measured. The displacement meter28may be either the contact type or the non-contact type. The movement amount of the bracket1is measured by the displacement meter28, thus the contract amount of the spring mechanism2installed on the motor unit attachment6can be confirmed. Further, the attaching procedure of the motor unit7is the same as that of the embodiment 1, so it will be omitted. The method for detaching the motor unit7from the motor bracket15is also the same as that of embodiment 1, so it will be omitted.

As mentioned above, the correct contract amount of the spring mechanism2can be seen by a numerical value by using the displacement meter28. In Embodiment 1, the last moved position can be determined as approval or disapproval, and if the displacement amount is furthermore found by the displacement meter28, the ascending distance can be judged accurately. As mentioned above, in the fine motion control rod drive mechanism handling apparatus using for attaching or detaching the fine motion control rod drive mechanism having the four kinds of components of a control rod drive mechanism body13, spool piece14, motor bracket15, and motor unit7to or from the reactor pressure vessel100, by the fine motion control rod drive mechanism handling apparatus having the motor unit attachment6for meshing the gear coupling21on the spool piece side with the gear coupling8on the motor unit side in the gear, the motor unit attaching operability is improved and the attaching operation time can be shortened.

As mentioned above, even when the gear coupling21on the spool piece side and the gear coupling8on the motor unit side do not mesh with each other in the gear, since the gear couplings can be immediately meshed with each other by the fine motion control rod drive mechanism handling apparatus including the bolt wrench assembly11ascending and descending on the motor unit7and the rotational mechanism for rotating the motor unit attachment6, the motor unit attaching operability is improved and the attaching operation time can be shortened. Further, the above rotational mechanism is provided with the rotational mechanism installed in the bolt wrench assembly11used in embodiment 1, and the rotational mechanism used in embodiment 2 and having the brake release mechanism26for releasing the brake of the motor unit7when the gear coupling21on the spool piece side and the gear coupling8on the motor unit side do not coincide with each other in the gears by the motor unit attachment6, and the counter-output shaft24for rotating the gear coupling8of the motor unit side.

As mentioned above, since the fine motion control rod drive mechanism handling apparatus has the load detection function (example, the load meter10) or the position detection function (for example, the limit switch9) for detecting the gear meshing state of the gear coupling21on the spool piece side and the gear coupling8on the motor unit side, it can be confirmed easily that the gears are meshing with each other.

As mentioned above, the motor unit attachment has the function (for example, the spring mechanism2) for releasing the pressing force of the motor unit7when the gear coupling21on the spool piece side does not mesh with the gear coupling8on the motor unit side in the gear, so that the gears and the like can be prevented from application of a large load.

As mentioned above, the motor unit attachment7can perform a more precise attaching operation by the fine motion control rod drive mechanism handling apparatus having the function for detecting the tip-root position of the gear of the gear coupling21on the spool piece side and the gear coupling8on the motor unit side and executing phase fitting for the gears of the gear couplings.

As mentioned above, since the motor unit attachment6has the function for positioning the motor unit in the rotational direction, it attaches the motor unit7in accordance with the positioning pin4of the motor unit attachment6in the rotational direction to prevent the position of the motor unit7in the rotational direction from changing. Thus the motor unit attaching operability can be improved and the attaching operation time can be shortened.

As mentioned above, the method of handling the fine motion control rod drive mechanism ascends the motor unit7to press each other in the gears, and in the pressed state, rotates the gear of the gear coupling8on the motor unit side when the gear coupling21on the spool piece side and gear coupling8on the motor unit side of the fine motion control rod drive mechanism do not mesh with each other in the gear. Accordingly, the motor unit attaching operability can be improved and the attaching operation time can be shortened.

As mentioned above, when pressing each in the gears, a motor unit attachment6having an elastic mechanism is used to press the gears, thus the gears can be prevented from application of a large load.