JPH02128193A - Exchange method of neutron counter cable and coiling device therefor - Google Patents

Abstract

PURPOSE:To facilitate the exchange work and treatment work of a nuclear reactor neutron flux monitor and contrive the reduction of exposure of workers to radiation by making a charged cable of a detection part in a neutron counter penetrate through a cask and housing a coiling detection part in the cask by a coiling device. CONSTITUTION:A cable 17 of a detection part 16 charged in a neutron counter of a reactor is arranged in the lower part of a reactor pressure vessel and penetrate a cask in which an opening and closing cover is provided in the upper part and a through hole in the lower part to connect to a coiling device arranged thereunder. The coiling device is driven to coil the cable 17 off so as to take the detector 16 into the cask, a cover is closed to coil the cable 17 on a drum part of the coiling device so as to house it, the cable 17 is cut by a cutter incorporated in the coiling device and the detector 16 housed in the cask and the cable 17 of the coiling device are separated are treated.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a method for replacing a neutron instrumentation tube cable in a nuclear reactor;
The present invention relates to the cable winding device.

(Prior art) In boiling water reactors, neutron source region monitors (
SOLlrCe Rengc Montor, hereinafter S
RM) and intermediate area monitor (Intermed i).
ateRenge Mon1tor1 (hereinafter referred to as IRM), but in place of this, a new neutron flux monitor wide range monitor (hereinafter referred to as WRNM) that can cover a wide range of neutron flux areas (from the neutron source area to the intermediate area) was installed.
) will be adopted.

By the way, in conventional SRM/IRM detectors, neutron detectors are movably arranged at several locations within the reactor core, and these neutron detectors are centrally controlled. :It is connected to the II board to monitor the neutron flux inside the reactor. That is, the neutron detector, which was centrally located outside the reactor core during operation, is inserted into the reactor core during periodic inspections and the like to confirm a decrease in neutron flux.

The neutron instrumentation tube is inserted into the SRM/IRM installed in the pedestal at the bottom of the reactor pressure vessel (hereinafter referred to as RPV).
This is done by a detector driver. The new neutron flux monitor WRNM is always fixed at a fixed position within the reactor core with its detection unit housed in a dry tube. Therefore, there is no need for a driving device, and there is no need to worry about malfunction when inserting the device for monitoring after an earthquake or accident.

Even with such a high-performance WRNM, if the reactor is operated for a long period of time, the IJ 215 coating on the detection part may deteriorate or other problems may occur, and in this case, it is necessary to replace it with a new WRNM. The need arises.

(Problem to be solved by the invention) When the WRNM breaks down and needs to be replaced, remove the reactor well cover above the RPV, remove the RPV insulation material, loosen the RPV stud bolts, remove the RPV head, and then The dryer housing and shroud head inside the RPV had to be moved underwater, the fuel assembly around the WRNM had to be temporarily moved, and after the WRNM was replaced, it had to be restored to its original state, which required many work days. there were. In addition, the work is performed by many workers, and workers are free to use their time.
There were concerns about A-ray exposure.

Generally speaking, when removing the WRNM from the upper part of the reactor, the dry tube is also removed at the same time, so handling the long dry tube is not easy. The dry tube also needed to be replaced.

The present invention was developed in view of these circumstances, and it facilitates the replacement and processing of reactor neutron flux monitors, reduces radiation exposure of workers, and improves plant operating efficiency. An object of the present invention is to provide a method for replacing a nuclear reactor neutron instrumentation tube cable and a cable winding device for the same.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a system in which the cable of the detection unit loaded in the neutron instrumentation tube of the nuclear reactor is placed in the lower part of the reactor pressure vessel and can be opened and closed in the upper part. A cask having a through hole provided in the lid and bottom of the cask is passed through the cask, and is further connected to a winding device disposed at the bottom of the cask, and the winding device is driven to wind up the cable, thereby winding the detector section. The cable section is pulled into the cask and the lid is closed, the cable section is wound up and stored on a drum section in the winding device, cut by a cutting device built into the winding device, and then put into the cask. It is characterized in that the housed detector section and the cable section within the winding device are processed separately.

The invention also includes a cable winding device movably disposed at the bottom of the reactor pressure vessel, and a cask detachably assembled to the top of the cable winding device and forming a space in the center, The cable winding device is characterized by comprising a cable winding drum, a cable pressing roller, a cable winding detection section, a cable cutting device, and a drum drive motor control device.

(Function) The cable of the detector loaded in the neutron instrumentation tube passes through the inside of the cask and is connected to the cable winding drum of the winding device, and is driven by this winding drum drive motor to wind the cable. . Then, store the detector unit attached to the tip of the cable inside the cask, close the lid of the cask, and then cut the cable with the cable cutting device inside the winding device to separate and remove the container and winding device. .

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 7. Before explaining this embodiment, the main parts of the nuclear reactor and the structure of the reactor wide range monitor will be explained with reference to FIGS. 7 and 8.

FIG. 7 shows the main parts of the reactor, where 1 is the RPV, and above the RPV 1 there is a reactor well, heat insulating material,
'RPVn etc. are installed.

Further, inside the RPV't, a shroud 2 is disposed integrally with the RPV1. Inside the shroud 2, a core support plate 3 and an upper grid plate 4 are provided horizontally. A core portion 5 is located between the core support plate 3 and the upper grid plate 4, and a fuel assembly (not shown) is loaded therein. An Incora housing 6 is arranged at the bottom of the RPVI. An in-core guide tube 7 is connected above the in-core housing 6 up to the core support plate 3, and a dry tube 8 is removably inserted into the in-core guide tube 7. The upper end of the dry tube 8 is seated at the bottom of the intersection of the upper grid plate 4.

A signal cable 10 is connected to the lower end of the in-core housing 6 by a connector 9, and this signal cable 10 is connected to a WRNM circuit 12 arranged outside the pedestal 11. Further, a control rod drive mechanism 13 is incorporated into a CRD housing 14 in parallel with the in-core housing 6 at the lower part of the RPVl.

FIG. 8 is an enlarged view of part A in FIG.
It is connected and fitted by 7. In addition, cable 1
An intermediate spacer 18 is connected to 7.

In such a configuration, replacement work is performed from the top of the furnace to the RP.
The conventional method was to release the VI, move the reactor internals (not shown), take out the dry tube 8 above the RPVI, and install a new dry tube 8 and WRNM 15 for replacement.

Next, an embodiment of the apparatus will be described with reference to FIGS. 1 to 6.

FIG. 1 shows a structural diagram of the cable winding device, and FIG. 2 is a front view of FIG. 1.

Reference numeral @21 is a trolley, which is equipped with movable wheels 22 on its lower surface, and can be freely moved and installed within a pedestal (not shown). A joint portion 23 is provided on the upper surface of the truck 21 to be combined with and connected to the cask 50 shown in FIG. 4, and a through hole is formed in the center, through which a cable is inserted. WRN (not shown) is attached to the penetration part of the joint part 23.
A cable drum 24 is provided for passing the M cable and winding the cable. cable drum 24
is assembled with a screw cap 25 so that the drum part can be separated into two parts so that the cable can be easily removed after being wound up. The cable drum 24 is rotated by an electric motor 26. In addition, the cable drum 24 is equipped with a manual handle 2 so that the couple can be wound even when the power is lost.
7 makes it possible to take LJ remotely. Switching between the electric motor 26 and manual handle 27 is done using gear part 2.
This is done by the clutch in 8.

The cable winding speed is controlled by the inverter 29 (
The cable winding speed can be changed freely. The cable winding length is measured by a roller 30 and a counter 31 located between the cable drum 24 and the splicing section 23. The cable wound around the cable drum 24 is cut by a cutting blade 32 and separated from the detection section. The cutting blade is driven by an air cylinder 34 that rotates an arm 33.

FIG. 3 shows a side view of FIG. Reference numeral 40 denotes a presser roller that presses down the cable wound around the cable drum 24, and presses the cable by operating an air cylinder 42 connected to an arm 41.

FIG. 4 shows an overall view of the cask assembled to the cable winding device of FIG. 1. 5 is a plan view of FIG. 4, and FIG. 6 is a side view of FIG. 4.

The body portion 52 has a cylindrical shape and is densely filled with shielding material so as to form a space in the center. Here, the space is open at the top and communicated with the outside through a small-diameter through hole at the bottom. Lid 5
1 is rotatably attached to the upper part of the body part 52 via a shaft, and is constantly applied with a force in the closing direction by a spring (not shown), and a lock pin is used to fix it to the body part 52 when it is closed. has been established. The inner cylinder, which is filled with a shielding material, is removably inserted into the space, and has an open upper part and a fixed bottom part with a small diameter through hole.

Next, a method of exchanging the WRNM will be explained.

After the reactor is shut down, the WRNM connector 9 in the pedestal 11 is released to separate it from the WRNM circuit 12, as shown in FIG. Then, the CRD replacement platform musk 50 and the winding device are installed and moved to a predetermined WRNM position. The wire of the winding device (not shown) is passed through the through hole in the bottom of the cask 50, passes through the inner cylinder, and is connected to the lower end of the cable 17 of the WRNM. In this state, when the winding device is operated to wind the wire rope (not shown) onto the drum 24, the WRNM connected to the wire (not shown)
The cable 17 is also gradually wound up on the drum 24 of the winding device. As the WRNM cable 17 is further wound up, the WRNM detection section 16 is removed from the dry duplex 8 and stored in the inner tube of the cask 50 as shown in FIG. 4, and the lid 51 is closed.

In this state, the cask 50 and the winding device are separated, and the cask 50 is moved to a predetermined position.

Furthermore, when installing a new WRNM detection section 16, it can be installed by directly inserting it into the dry tube 8.

Therefore, according to the above configuration, the following effects can be achieved.

(1) There is no need to remove the WRNM from above the RPV, and the effort of opening the upper part of the furnace to replace only the WRNM after operation can be omitted, which greatly contributes to improving the operating rate of the plant.

(2) When using WRNM in the upper part of the furnace, it is necessary to handle the dry tube at the same time when replacing the WRNM.
The dry tube must also be replaced with a new one, but since the WRNM is wound up at the bottom of the furnace and replaced, it can be handled continuously. Therefore, the handling operation can be performed without stopping midway, there is no need to worry about things getting caught, and it is possible to eliminate the waste of replacing the dry duplex.

(3) Since the detection part with a high radiation dose can be remotely controlled to be stored in the cask immediately after being pulled out from the dry tube, there is no radiation exposure to the workers and this leads to improved work efficiency.

Although the above embodiment describes a method for replacing the detection section 16 of a WRNM, the present invention can also be applied to the case of replacing the detection section of a conventional nuclear reactor neutron flux monitor. Further, the Kireshu 50 winding device may be detachably attached to a frame which is movable within the pedestal 11 in addition to the CRD exchange platform.

[Effects of the Invention] According to the present invention, the detection section of the reactor neutron flux monitor can be handled and housed in the cask by remote control.

Therefore, after removing and opening the reactor well cover, PCV head, heat insulating material, RPV head, dryer housing, shroud head, and fuel assembly in the upper part of the reactor, the detection part of the reactor neutron flux monitor was replaced and the original condition was restored. This eliminates the need for recovery work, which greatly improves work efficiency.

It can also greatly contribute to improving the operating rate of nuclear reactors.

[Brief explanation of the drawing]

Fig. 1 is a structural diagram showing an embodiment of the cable winding device according to the present invention, Fig. 2 is a front view of Fig. 1, Fig. 3 is a side view of Fig. 1, and Fig. 4 is a diagram of Fig. 1. FIG. 5 is a front view of FIG. 4, FIG. 6 is a side view of FIG. 4, and FIG. 7 is an overview of the main components of a nuclear reactor related to the present invention. FIG. 8 is a side view, partially in cross section, of the structure of a wide range monitor related to the present invention. 1...Reactor pressure vessel 5...Reactor core 8...Dry tube 11...Pedestal 12...WRNM circuit 15...WRNM 16...Detection section 17...Cable 21...・Dolly 23...Joint part 24...Cable drum 25...Screw cover 26...Electric motor 27...Manual handle 28...Gear part 19...Inverter 30...Roller 31 ... Counter 32 ... Cutting blade 33 ... Arm 34 ... Air cylinder 40 ... Presser roller 50 ... Cask 51 ... Lid

Claims (2)

[Claims] (1) The cable of the detection unit loaded in the neutron instrumentation tube of the reactor pressure vessel is placed at the bottom of the reactor pressure vessel, with a lid that can be opened and closed at the top and a through hole at the bottom. The cable is passed through the cask and further connected to a winding device disposed at the bottom of the cask, and the winding device is driven to wind up the cable to draw the detector section into the cask, and to open the lid. The cable section is wound and stored on a drum section in the winding device, and is cut by a cutting device built into the winding device, and the detector section housed in the cask and the winding device are cut. A method for replacing a neutron instrumentation tube cable, characterized by separating the cable from the cable inside the device. (2) Equipped with a cable winding device movably disposed at the bottom of the reactor pressure vessel, and a cask detachably assembled at the top of the cable winding device and forming a space in the center. A neutron instrumentation tube cable winding device, characterized in that the cable winding device comprises a cable winding drum, a cable pressing roller, a cable winding detection section, a cable cutting device, a drum drive motor, and a control device.