JPH05312992A - Repair method for core structure and water seal chamber - Google Patents

Abstract

PURPOSE:To reduce exposure of workers by performing preventive maintenance and repair, keeping the laid in-reactor equipment in air environment and keeping the reactor chamber and the outside of small chamber filled with reactor water. CONSTITUTION:In-reactor chamber main body 8 is constituted of a guide pipe 9 for using in inserting various devices for preventive maintenance and repair and surveillance devices in the chamber, a guide 10 for insertion, an extending arm 11 capable of fixing the heads of the various devices, a placing and fixing mechanism 15 to fix the chamber main body, a gas supply pipe 12 to supply gas, a guide drive mechansim 22 and a reactor chamber control device 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to preventive maintenance, repair and replacement of reactor internals, and more particularly to a compact reactor chamber utilizing a shroud structure and capable of following narrow spaces. It relates to the structure of the chamber.

[0002]

2. Description of the Related Art A conventional reactor pressure vessel 1 is replaced by a conventional water supply sparger replacement method, for example.
The work is carried out with the water inside drained. Under the present circumstances, a shielding wall is installed on the inner surface of the reactor pressure vessel 1, and a worker enters the reactor pressure vessel 1 and carries out each work by using some remote devices. Therefore, in consideration of preventive maintenance, repair, and replacement work of the reactor internal structure in the future, it is necessary to establish a remote construction method in consideration of reduction of exposure of workers.

[0003]

In the above-mentioned prior art, no remote replacement method has been established as represented by the replacement method of the water supply sparger, and the radiation from the inside of the reactor is shielded in the air. It was difficult to reduce the exposure of workers by using a shield.

An object of the present invention is to raise the water level of a nuclear reactor in preventive maintenance, repair and replacement work of a core support and a core structure represented by a shroud 2, an upper lattice plate 5 and a core support plate 6. In this state, the core support structure is utilized to provide a reactor internal chamber suitable for remote automation of work and reduction of worker exposure.

[0005]

A chamber in a reactor according to the present invention for solving the above-mentioned problems is provided in the reactor pressure vessel in a state where reactor water is held in the reactor pressure vessel. A steam dryer mounted on the core shroud, a device such as a shroud head and a steam separator, and the like,
Then, the fuel assembly, the control rod guide tube, and the like in the core shroud are removed, and the chamber main body is installed and fixed using the upper end flange surface and the lug of the core shroud. However, before this work, a seal plug is installed in the nozzle part located above the jet pump installed in the reactor pressure vessel to prevent running water to the lower part in the reactor pressure vessel. Next, a gas is supplied from the upper part of the chamber in the reactor to create an air atmosphere in the chamber and the lower part of the shroud, and a guide and a device for inserting the device into the air atmosphere part in the shroud from the upper part of the chamber in the reactor. Preventive maintenance and repair work can be performed by inserting various device heads using the operation arm.

A small chamber that can be inserted by a wire or the like is installed and fixed in the narrow portion between the shroud and the reactor pressure vessel by using the outer wall of the shroud and the inner wall of the reactor pressure vessel. The small chamber has a plurality of driving units capable of driving the beds of various devices, with the inside of the chamber made into an air atmosphere by supplying gas using a plurality of air bags.

[0007]

According to the reactor internal chamber and the small chamber of the present invention, reactor water enters the outside of the reactor internal chamber while keeping the inner surfaces of the existing shroud, shroud support cylinder, and shroud support leg in the air atmosphere. In this state, the equipment for preventive maintenance and repair of internal structures such as the shroud, shroud support cylinder, shroud support leg, upper lattice plate, core support plate, etc. is installed from the upper part of the chamber in the reactor to the equipment insertion guide and the equipment operation arm. By inserting by using, it is possible to improve the reliability of preventive maintenance and repair, and reduce the exposure of workers.

According to the small chamber of the present invention, only the outside of the existing shroud and part of the inside of the reactor pressure vessel are put into the atmospheric atmosphere, and then the reliability of preventive maintenance, repair, etc. of the part is improved and the operator's reliability is improved. The exposure can be reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows an example of the overall configuration of an internal reactor chamber used in this embodiment and a state in which a small chamber is inserted.

In this embodiment, the reactor internal chamber body 8 is installed and fixed on the flange surface of the shroud 2, and the telescopic arm 11 is extended from the guide pipe 9 above the reactor internal chamber body 8.
Is fixed at an arbitrary position, and the small chamber body 24 is installed outside the shroud 2 at the same position as the telescopic arm 11. In the same figure, the reactor pressure vessel 1 is shown as a cross section, and the shroud 2, shroud support cylinder 3, 3 of the reactor internal structure directly related to the reactor internal chamber body 8 and the small chamber body 24 of the present invention. Only the shroud support leg 4, the upper lattice plate 5, the core support plate 6, and the jet pump 7 are shown.

Therefore, the steam dryers, steam separators, shroud heads, fuel assemblies, etc., which are other internal reactor structures, are excluded.

The in-reactor chamber main body 8 is a telescopic unit that can fix the guide pipe 9, insertion guide 10 and heads of various devices used for inserting various devices for preventive maintenance and repair and monitoring devices into the chamber. It comprises an arm 11, a device fixing mechanism 15 for fixing the chamber body, a gas supply pipe 12 for supplying gas, a guide drive mechanism 22, and a reactor chamber control device 23. As for the handling of the chamber body 8 in the reactor, with the preventive maintenance of the reactor water level in the shroud 2 or the like, or in a state where the repair target is equal to or lower than the repair target part, a dedicated suspender or a suspender prepared in the existing nuclear power plant, The suspender rod 16 and the guide rod installed in the reactor pressure vessel 1 are used for positioning and fixing to the upper flange portion of the shroud 2. Next, while supplying dry gas from the gas supply pipe 12, the reactor water level is raised to below the flange of the reactor pressure vessel 1, and the shroud 2
The inside is made to be an air atmosphere. However, at this time, in order to prevent the reactor water from flowing into the shroud 2, the seal plug to the nozzle portion of the jet pump 7 installed in the reactor pressure vessel 1 and the valve of the recirculation piping portion are closed. It is carried out in the state where the above has been done. In preventive maintenance and repair work,
When the outer wall side of the shroud 2 also needs to be in the air atmosphere, the small chamber body 24 is installed in advance and the inside of the chamber is kept in the air atmosphere state. After confirming that there is no abnormality in the reactor main body 8 and the small chamber main body 24 by the monitoring camera and the illumination 33, various devices are attached to the tip of the telescopic arm 11 using the guide pipe 9 and the insertion guide 10. Then, the guide drive mechanism 22 is operated by the in-reactor chamber control device 23 to the preventive maintenance or repair target position, and positioning and fixing are performed. After that, preventive maintenance or repair work is performed. It should be noted that operation monitoring such as insertion, positioning, fixing and pulling out of various devices is performed by the monitoring camera, the illumination 33 and the like. Also,
The in-reactor chamber body 8 has a structure in which the service platform 32 can be attached to the flange surface of the reactor pressure vessel 1 in consideration of the operation of putting in and out various devices and cables from the guide pipe 9.

FIG. 2 is a block diagram of the chamber body 8 in the nuclear reactor. The insertion guide 10 has a structure in which a plurality of guide auxiliary pads 17 are arranged so that the guide pipe 9 can be inserted into the guide pipe 9 with high positional accuracy and smoothly. The operation of the telescopic arm 11 can be driven in various directions by an arm swing-up mechanism 18 and an air cylinder driven by an air cylinder, or a telescopic mechanism driven by an electric motor, and a guide drive mechanism 22 driven by an electric motor. .. Further, it is possible to attach various device heads to the arm fixing head 19 and press them against the inner wall of the shroud 2. Water seal mechanism 2 with upper flange of shroud 2
Reference numeral 1 denotes a sealing mechanism by supplying an O-ring and gas, and a device fixing mechanism 15 enables tightening between the lug portion of the shroud 2 by driving an air cylinder or the like, and is installed in the reactor pressure vessel 1 when the device is installed. The guide block 34 is provided so that the existing guide rod can be used as an installation guide. Next, surveillance camera and lighting 33
In order to monitor the entire inside of the chamber body 8 in the nuclear reactor, a plurality of them are installed in the chamber, and rotation and swing drive can be performed by remote control. It should be noted that each device head attached to the arm fixing head 19 has a structure in which a dedicated surveillance camera and a dedicated illumination are attached.

FIG. 3 shows an example of the overall configuration of a small chamber used in this embodiment. In this embodiment, the shroud 2 is inserted and fixed between the shroud 2 and the reactor pressure vessel 1, and
The vertical cross section is shown when performing work such as preventive maintenance and repair on any outer surface of the.

The small chamber body 24 is inserted into the small chamber main body 24 with a wire or the like by a suspending method, and a propulsion device 36 for roughly positioning the device, a fixing pad 25 for fixing the device,
Air bag 26 for water sealing for sealing the reactor water to the opening located in the front of the chamber, for opening the water sealing for sealing the reactor water in the chamber which can be opened and closed freely An air bag 27, a drive mechanism 28 capable of driving a plurality of axes of various device heads, a gas supply port 29 for supplying a dry gas into the chamber, a gas exclusion port 30 for excluding the gas, and an overall monitoring of the inside of the chamber. It is composed of a monitoring camera and lighting 35, and a small chamber control device 31. The small chamber body 24 is handled such that it can be attached for preventive maintenance or even when the repair target is in the air or underwater. An example underwater condition
Will be explained. FIG. 4 shows a vertical cross section when the shroud 2 and the reactor pressure vessel 1 are inserted into arbitrary positions. Figure 5
Shows a plan view when positioning and fixing to an arbitrary place. When inserting the chamber into an arbitrary position, air is supplied to the opening water sealing air bag 27 to seal the reactor water in a state where the guide bar 37 is bulged upward with the guide, and the dry gas is supplied by the gas supply port 29. While the chamber is being supplied with air, the structure is such that it can be moved to any position by the thrust of a plurality of propulsion devices 36 arranged above and below and to the left and right of the chamber. Positioning and fixing the chamber
Performed by a fixing pad 25 that is driven by an air cylinder, and then supplies air to a plurality of water sealing air bags 26 that are arranged on the front surface of the chamber to inflate and seal the reactor water. Air bag 2
It has a structure that can be shortened by removing the air in 7. In this state, the drive mechanism 28 to which various device heads are attached is remotely operated by the small chamber control device 31 to perform preventive maintenance or repair work. It should be noted that abnormality monitoring in the chamber and operation monitoring of various apparatus heads are performed by a monitoring camera and an illumination 35 which are installed in the chamber and can rotate and swing.

[0016]

According to the chamber and small chamber of the present invention, while maintaining the inside and outside surfaces of the existing shroud, the upper lattice plate, the core support plate, the shroud support cylinder, the shroud support leg, etc. in the air atmosphere, It is possible to improve the reliability of preventive maintenance and repairs and reduce the exposure of workers while the reactor water and the small chamber are filled with reactor water.

[Brief description of drawings]

FIG. 1 is a sectional view of a chamber in a nuclear reactor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a chamber in a nuclear reactor.

FIG. 3 is a cross-sectional view of a small chamber in a repair work state.

FIG. 4 is a plan view of a repair work state of a small chamber.

FIG. 5 is a transverse cross-sectional view of a small chamber inserted into a nuclear reactor.

[Explanation of symbols]

1 ... Reactor pressure vessel, 2 ... Shroud, 3 ... Shroud support cylinder, 4 ... Shroud support leg, 5 ...
Upper lattice plate, 6 ... Core support plate, 7 ... Jet pump, 8
... Reactor chamber body, 9 ... Guide pipe, 10 ... Insertion guide, 11 ... Telescopic arm, 12 ... Gas supply pipe, 13 ... Lower fixing ring, 14 ... Upper fixing ring, 15 ... Device fixing mechanism, 16 ... Hanging tool rod, 17 ...
Guide assist pad, 18 ... Arm raising mechanism, 22 ...
Guide drive mechanism, 23 ... Reactor chamber control device, 2
4 ... Small chamber body.

Front Page Continuation (72) Inventor Yunobu Sato 3-2-2 Sachimachi, Hitachi City, Ibaraki Prefecture Hitachi New Engineering Co., Ltd. (72) Noriaki Wada 3-1-1, Saiwaicho, Hitachi City, Ibaraki Prefecture No. 1 Hitachi Ltd., Hitachi Works (72) Inventor Koichi Kurosawa 3-1-1, Saiwai-cho, Hitachi, Ibaraki Hitachi Ltd. Hitachi Works, Hitachi (72) Inventor, Hiroshi Tsujimura Saiwaicho, Hitachi, Ibaraki 3-1-1, Hitachi Ltd., Hitachi Works (72) Inventor, Kunio Enomoto, 502, Kamidate-cho, Tsuchiura-shi, Ibaraki Hiritsu Seisakusho Co., Ltd.

Claims (4)

[Claims] 1. A shroud inside a reactor pressure vessel and a shroud within a reactor pressure vessel for preventive maintenance, repair and replacement of core support and core internals attached to the core and lower part of the reactor pressure vessel. Even if the removable equipment is removed and a water seal chamber is installed using the upper flange surface of the shroud, and the water level of the reactor is raised up to the lower part of the flange of the reactor pressure vessel, the water is introduced into the shroud. The inflow of reactor water is blocked by enclosing gas, etc., and various devices inserted from the upper part of the water seal chamber while keeping the entire inside of the shroud in the air are installed on the entire inside of the shroud and installed. A method for repairing an in-core structure, characterized in that the preventive maintenance, repair and replacement work of a core support structure can be performed remotely underwater. 2. The guide according to claim 1, wherein a guide rod is attached to an inner wall of the reactor pressure vessel at an upper flange portion of the shroud, and a bracket and a lug are attached to an upper portion of the shroud. A block and a device fixing mechanism are provided, and a water sealing mechanism for keeping the entire inside of the shroud in the air, a gas supply pipe and various devices, and a guide pipe necessary for putting in and out a cable, an insertion guide and various devices are provided. Provided with a telescopic arm that can be attached to move to any position and a guide drive mechanism,
A monitoring chamber that can monitor the entire surface of the water seal chamber and a chamber inside the reactor that also has lighting. 3. The device according to claim 1, which can be inserted into the narrow portion between the reactor pressure vessel and the shroud by suspending a wire or the like, and from a plurality of air bags for putting the chamber into an air state. A small chamber that has a water seal mechanism that is configured, can be moved to any position by the thrust of multiple thrusters, and has a fixing mechanism for positioning and fixing. 4. A surveillance camera for monitoring the entire surface of the chamber according to claim 3, further comprising a drive mechanism capable of mounting various device heads in the small chamber and driving the heads to arbitrary positions. A small chamber that also has illumination and that enables the preventive maintenance, repair, and replacement of the outer surface of the shroud and the like simultaneously or independently with the water seal chamber underwater remotely.