JPS6142837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control rod drive device (CRD) exchanger for a boiling water nuclear reactor, and particularly to a protection device for preventing collisions during replacement work in this exchanger.

Generally, in a boiling water reactor, the control rods that control the reactor's output and the power distribution within the reactor core are
The position of the rods is controlled by a hydraulic control rod drive device (hereinafter referred to as CRD) installed outside the reactor pressure vessel, and a malfunction occurred during regular inspections.
The CRD can be separated from the control rods and CRD housing and transported outside the containment vessel for repair, or a new control rod drive device can be transported to the lower part of the reactor pressure vessel inside the containment vessel and reinstalled. It's on.

As described above, since CRD replacement work requires a large number of workers, there is a strong demand for remote control and automation in order to reduce radiation exposure and speed up replacement work.

On the other hand, in addition to many CRDs, the lower part of the pressure vessel of the above reactor, that is, the pedestal, contains guide pipes for the neutral region monitor (SRM), intermediate region monitor (IRM), and local power monitor (LPR).
The guide tubes and various neutron measuring devices of M) are complicated and are installed in large numbers, especially the S.
Each of the RM and IRM guide pipes hangs long from the pressure vessel, and many of these cables hang low.

Therefore, when replacing a conventional control rod drive unit using a replacement machine, the control rod drive unit must be moved horizontally while being held vertically, avoiding the low parts that grip the guide tubes of each SRM and the cable guide tubes of the LPRM. Next, this is rotated within the pedestal, held horizontally, and then transferred to a cart and transported outside.

However, in the replacement work using the above-mentioned exchanger, if there are misoperations or various cables or equipment hanging down in unexpected places, the guide tubes of control rods etc. may collide with them and be damaged, or the regular inspection period may be extended. This causes a decrease in the operating efficiency of nuclear power plants.

In view of the above-mentioned points, the present invention provides a platform trolley with a lifting device for gripping the control rod drive device, and a pair of conductive detection members are attached to this lifting device. Detects contact with equipment and various cables to prevent damage to them, speeds up replacement work to prevent exposure to radiation, shortens periodic inspection periods, and improves operating efficiency of nuclear power plants. The present invention provides a control rod drive device exchanger for the following purposes.

Hereinafter, the present invention will be described with reference to an illustrated embodiment.

In FIGS. 1 to 3, reference numeral 1 denotes a pedestal equipped with an entrance 3 through which a control rod drive device 2 is brought in using a moving cart (not shown). A rail 4 is installed horizontally, and a platform (also referred to as a turntable) 5 is rotatably provided on the rail 4. Further, a cart 6 is provided on the platform 5 so as to be movable in the horizontal direction, and a lifting device (also referred to as a rotating device) 7 is provided on the cart 6 so as to rotate approximately 90 degrees around a support shaft 8. It is set up so that it can be moved. Furthermore, a pair of gripping members 9 are attached to a part of this raising/lowering device 7, and the control rod drive device 2 extracted from the control rod drive device housing 10 is detachably attached to each of the gripping members 9. It is becoming more and more gripped.

On the other hand, a pair of arm rods 11 are rotatably mounted around a support shaft 12 at one end (upper end in FIG. 1) 7a of the lifting device 7.
A conductivity detection member 13 made of, for example, a copper wire and having a substantially donut shape is provided on the free end portion 11a of the control rod drive device 2 so as to surround the upper portion 2a of the control rod drive device 2 from the outside. In addition, a substantially donut-shaped conductivity detection member 14 made of copper wire that can be divided into two parts is provided in a part of the lifting device 7 so that it can be separated from the control rod driving device 2 by opening its legs. The conductivity detection members 13 and 14 are connected to a ground fault detection device 15 which is grounded (earthed) as shown in FIG. Furthermore, this ground fault detection device 15
is connected to a trip device 16, and the signal from this ground fault detection device 15 activates the trip device 16 to issue an alarm, and at the same time stops the operation of the exchange.

On the other hand, an electric motor 17 is provided near the support shaft 12 of the arm rod 11, and a worm 18 is mounted on the output shaft of the electric motor 17. A worm wheel 19 is engaged with the worm 18, and the worm wheel 19 is rigidly mounted on the base 14a of the conductivity detection member 14 via a connecting rod 20.

Therefore, as shown in FIGS. 1 and 2,
In the process of gripping the control rod drive device 2 pulled out from the control rod drive device housing 10 with each of the gripping members 9 of the raising/lowering device 7 and moving the trolley 6 to a predetermined position, each of the conductivity detection members 13 and 14 When it collides with various cables or equipment hanging below the pedestal 1, current flows and the ground fault detection device 15 is activated, and the signal from this ground fault detection device 15 activates the trip device 16 to issue an alarm. At the same time, the operation of the hoisting device 7 and the truck 6 is stopped.

In this way, the replacement work can be performed safely using the exchanger without damaging the various cables, equipment, control rod drive device 2, etc. mentioned above.
In particular, each of the conductive detection members 13 and 14 is elastic and highly flexible, so that the size of the collision can be detected based on the size of the contact.

On the other hand, when the truck 6 and the platform 5 move to a predetermined position, the raising/lowering device 7 rotates approximately 90 degrees to the left around the support shaft 8 to hold the control rod drive device 2 horizontally.

By driving the electric motor 17, the arm rod 11 rotates to the right around the support shaft 12, and on the other hand, by rotating the worm wheel 19 meshing with the worm 18. , the other conductivity detection member 14 opens its legs and separates from the control rod drive device 2 . Next, each of the gripping members 9 is released, and the control drive device 2 is transferred to a moving cart waiting at the entrance 3 and carried out.

As described above, according to the present invention, the carriage 6 of the platform 5 is provided with the lifting device 7 for gripping the control rod driving device 2, and the pair of conductive detection members 13 and 14 are attached to the lifting device 7. The conductive detection members 13 and 1 are attached so as to surround the drive device 2.
4 is connected to the ground fault detection device 15, and this ground fault detection device 15 is connected to the trip device 16.
During replacement work, not only does it detect contact with equipment inside the pedestal and various cables, eliminating the risk of damaging them, but it also automatically detects collisions with cables, etc., reducing work time and reducing radiation exposure. In addition to preventing this, the structure is also small, so handling and operation are easy.

[Brief explanation of the drawing]

FIG. 1 is a side view of an exchanger for a control rod drive device according to the present invention, FIG. 2 is a perspective view showing only the essential parts of the present invention, and FIG. 3 is a system diagram of the present invention. 1...Pedestal, 2...Control rod drive device, 5
. . . Platform, 6 . . . Dolly, 7 . . . Lifting device, 11 .

Claims (1)

[Scope of Claims] 1. A platform trolley is provided with a lifting device for gripping the control rod drive device, a pair of conductive detection members are attached to the lifting device so as to surround the control rod drive device, and each conductive detection member is attached to the lifting device so as to surround the control rod drive device. The member is connected to a ground fault detection device, and this ground fault detection device is connected to a trip device, so that when replacing the pedestal, contact with equipment and various cables in the pedestal is detected to prevent damage to them. Control rod drive exchanger. 2. One conductivity detection member is formed into a substantially donut shape using a copper wire material, and the other conductivity detection member is formed into a substantially donut shape so that it can be divided into two to enclose the control rod drive device. An exchanger for a control rod drive device according to claim 1.