KR100281425B1 - Heater replacement device for pressurizer for nuclear power plant - Google Patents

Abstract

The present invention relates to a welding repair apparatus for replacing a heater (4), which is a part of a pressurizer (1) for a nuclear power plant, and a working procedure for carrying out the replacement of the heater (4) of the pressurizer (1) for a nuclear power plant. The cutting and processing work, which is dependent on the manual device, and the welding process are difficult for the operator to perform the efficient work in the radioactive polluted area, and it requires a lot of manpower and cost. It was being influenced. Therefore, the establishment of the apparatus and the working process according to the present invention is to solve the problems as described above, using the welding device 41 combined camera-monitoring system, the operator controls the welding situation even at a distance of 30M In order to improve the handleability of the cutting device, a device capable of welding has been developed. Nuclear power generation is provided in which the standard detachable clamp head 25 is retrofitted and the chip protection cover 52 is attached to the clamp head 25. The present invention relates to a method and apparatus for replacing a heater of a pressurizer.

Description

Heat exchanger replacement method and device of pressurizer for nuclear power plant

The nuclear pressurizer is connected from the nozzles of the inlet and outlet of the reactor in the nuclear power plant to maintain a constant operating pressure and serves as a buffer tank to compensate for the volume change of the coolant generated when the coolant is heated and cooled. This pressurizer minimizes the pressure change by controlling the heater power installed in the lower part and the cooling spray installed in the upper part in the transient state, and the inside of the pressurizer is maintained in a saturated mixture of steam and water of 652 ° F. and 2250 Psi during normal operation.

However, industrial boiler equipment or small pipes in nuclear power generators that are in normal operation after completion of installation are frequently damaged or damaged due to the end of natural life according to the years of use or the inadequate operation. Partial replacement and repair of damaged and damaged parts is needed to reduce costs and shorten downtime rather than to reinstall equipment.

Therefore, the heater of the pressurizer for nuclear power plants as described above is a place where such damages and breakages frequently occur. To remove the existing damaged and broken heaters and replace them with new heaters, the welding part of the heater is cut and welded to the pipe. Although cutting and processing with an improvement device and welding by a welding torch, the worker has to be exposed for a long time in a radioactive polluted area. Therefore, there is always a risk of safety accidents. In the related art, it is entirely dependent on the proficiency of the worker, and thus, the work efficiency is reduced due to the work process that is not established. Therefore, it is very important to develop a new welding apparatus and to establish a work process that can perform it correctly.

The present invention has been made in order to solve the problems described above, cutting and processing the heater and sleeve with a heater cutting device and pipe end improvement device to replace the heater directly by the operator in the current pollution area, a lot of radiation exposure After cutting and processing the welding torch with a welding torch is performed in a short time, the operator performs directly at the work site, and the welding work takes a long time, so that the remote control is possible, that is, by attaching a camera to the conventional welding head The camera was switched to a welding device that allows welding while controlling the welding situation through a remote TV monitor with a camera-monitoring system. Install two cameras that can be observed before and after Connect to an eBlo monitor, insert a special filter into the camera to see the camera's strong welding light of about 6000 ° C, fix the camera's scanning speed to its maximum value, and prevent overheating of the camera due to prolonged use The cooling water line was connected to the camera housing to enhance cooling.

In general, the welding power supply has a short power supply cable connected to the welding head, so the arc voltage drop characteristic of the change in the length of the power supply cable, that is, the electrical signal (voltage) transmitted from the welding power supply to the welding head is connected to the welding head. The length of the cable is affected. According to the test of this welding device, if the cable length is less than 10M, the electric signal supplied from the power supply is transmitted to the welding head without difficulty, but if the cable length is more than 20M, the minimum voltage required for arc generation As the voltage drop phenomenon that is not transmitted to the welding head occurs and welding does not proceed, in the case of the device of the present invention, since the remote control is performed through a cable having a length of 30M due to the remote control, the voltage in the power supply circuit Output cable of welding power supply to prevent falling and noise of cable Junction box of which a cable connection block and the weld head (JUNCTION BOX) was attached to the reinforced filter circuit which can deliver and maintain a constant voltage applied to the internal PCB.

In addition, since the working conditions in a narrow space should improve handling efficiency only when the required tools are handled well, the standard clamp head in the conventional cutting device is heavy (about 10 kg). Since the clamp head is manufactured as a separate type, it takes a long time to install it on the workpiece. The clamp head is integrated to improve the work efficiency. Also, to prevent the chips generated during cutting of the heater from falling to the floor, the clamp Attaching the protective cover to the head portion can correctly establish the procedure of the entire process from initial preparation to completion through proper performance of the devices can improve the performance of the heater replacement construction.

1 is a vertical sectional view showing a schematic configuration of a pressurizer for a nuclear power plant,

2 is a partially enlarged view of the heater portion of FIG. 1, FIG.

3 is a schematic configuration diagram of a welding part cutting device;

4 is a schematic configuration diagram of a tip improving device for improving an inner surface of a pipe of a cut heater;

5 is a schematic configuration diagram of a welding apparatus for joining a sleeve and a replaced heater;

6 is a perspective view of the bonding state of the welding device and the camera housing of FIG. 5;

7 is a front view of a state where the detachable clamp head of FIG.

8 is a front view with a protective cover attached to the integrated clamp head.

<Explanation of symbols for main parts of the drawings>

One… Pressurizer; Spray nozzle,

3... Safety valve, 4.. Heater,

5... Heater support skirt, 6.. SURGE nozzles,

7... Level measuring nozzle, 8... Temperature measuring nozzle,

9... Heater support plate, 10... sleeve,

11... Cutting and welding, 21.. Cutting device,

22... Pressure control valve, 23.. Pneumatic motor,

24,24 '... Byte feeder, 25... Clamp head,

26... Truncation bite, 31... Tip improver,

32... On / off switch, 33... Processing bite,

34... Clamping screw, 41.. Welding equipment,

42... Weld head, 43... Tungsten rod positioning,

44... Filler metal positioning portion, 45... Filler metal positioning screws,

46... Welding torch, 47... Brackets,

51... Cutting chip, 52... Protective cover,

61... Camera, 67... Camera cable,

63... Special filter, 64... Triangular Prism,

65... Cooling water line, 66... Camera housing.

Hereinafter, the configuration and operation of the present invention in detail based on the drawings.

The apparatus of the present invention is used for the replacement work of the heater 4, which is part of the components of the pressurizer 1 for the nuclear power plant as shown in FIG. 1, and the welded portion of the heater 4 and the sleeve 10 shown in FIG. A device for cutting and processing, and inserting a new heater at the tip of the improved sleeve 10 to weld and join the sleeve 10 and the heater 4, the overall configuration of the apparatus of the present invention is shown in FIG. As shown in FIG. 7, the pressure control valve 22, the pneumatic motor 23, the integrated clamp head 25 of FIG. 7, the bite feeding part 24, and the cutting bite 26 are used for cutting and improving the welded surface. 8, a welding part cutting device 21 having a protective cover 52 attached to the clamp head 25; As shown in FIG. 4, the pipe tip improving device including an on / off switch 32, a clamp fixing screw 33, a bite feeder 24 ′, and a processed bite 34 for the pipe (sleeve) surface improvement process. (31); As shown in FIG. 6, two cameras 61 attached before and after the welding head 42 of the welding torch 46 are used to remotely control the welding state through a TV monitor, and to heat the heater 4 and the sleeve 10. ) Is a welding device 41 for joining by welding.

The welding torch 46 is composed of a welding head 42, a tungsten rod positioning portion 43, a filler metal positioning portion 44, and a filler metal positioning screw 45, as shown in Figure 5, the camera housing 66 Assembled in the inside of the camera 61 is installed on the body of the welding head 42 using the bracket 47, the camera 61 is attached to the left and right around the tungsten rod is fixed in the direction toward the end of the tungsten rod.

As shown in FIG. 6, the camera cable 67 is directly connected to the camera 61, and the camera housing 66 is connected to a cooling hose through the processed cooling water line 65 to circulate the cooling water (distilled water), thereby using for a long time. To prevent overheating of the camera 61, and by attaching a triangular prism 64 to the end of the camera housing 66, an external image of the camera perpendicular to the prism 64 is refracted by 90 ° to be captured by a camera lens. Afterwards, it appears as a TV monitor. This method can be advantageously used when the installation conditions for the camera direction to which the tungsten rod should be pointed are difficult, and the special filter 63 can be used to observe the very high temperature welding arc. Inserted into the reassembled, the special filter 63 is a state in which a black spot is drawn in the center of the film.

Work process for repairing the heater of the pressurizer for nuclear power plants using the apparatus as described above is as follows.

1) Work Preparation

-Check technical specifications (welding procedure specifications, etc.)

-Welder and work tool movement

-Confirm required materials

-Check the power supply line

2) Free up workplace space

-Prepare protective equipment for safety

3) Removing the heater

-Display of welded parts of damaged and damaged heaters

-Fixing the cutting device to the sleeve

-Cutting operation

-Cut off the heater

4) Improvement of heater sleeve

Internal observation of the cut sleeve

-Improved sleeve tip

5) heater welding

-Insert a new heater into the sleeve

-Welding sleeve and heater

-Clean welding area

6) weld inspection

-Carry out the inspection according to the liquid penetrant inspection (PT) procedure

-Fix welding when defect is found

7) Arrangement and Demolition of Workplace

-Clean around the workplace

-Work tool, move out after welding machine decontamination

-Release safety guards installed around the workplace

Referring to the effect of the method and apparatus for replacing the heater of the pressurizer for a nuclear power plant of the present invention made of the above objects and configurations as follows.

Working environment conditions in a radioactive contaminated area or a narrow area with limited worker access should be reinforced by the ability to remotely control the working situation using a camera-monitoring system and to easily handle necessary devices. It is possible to smoothly perform the work process as described above, the devices of the present invention can be used in combination with other devices as necessary by changing the use of each conventional device manually operated, in particular, the work procedure is very demanding By establishing a work process that can be applied to work in radioactive contaminated areas, a high level of application technology is secured.

Therefore, the present invention can improve the work efficiency and protect valuable lives by allowing the operator to work safely in a nuclear power plant or other radioactive polluted area where safety is a top priority, and in view of the overall know-how of operating a nuclear power plant. It has the advantage of making a small contribution to accumulation.

Claims (4)

Welder cutting device 21 consisting of pressure control valve 22, pneumatic motor 23, clamp head 25, bite feeder 24, cutting bite 26 for cutting and improving the welded part; ; A pipe tip improving device 31 composed of an on / off switch 32, a clamp fixing screw 34, a bite feeding part 24 ', and a processing bite 33 for pipe (sleeve) inner surface improving process; The welding situation is carried out through a TV monitor with two cameras 61 attached together with the camera housing 66 using brackets 47 before and after the welding head 42 around the tungsten rod of the welding torch 46. Heater replacement device for a pressurizer for a nuclear power plant, characterized in that the remote control is composed of a welding device 41 for coupling the heater (4) and the sleeve (10) by welding. The method of claim 1, The clamp head (25) is made in one piece, the protective cover 52 is attached to the heater replacement device for a nuclear power plant, characterized in that attached. The method of claim 1, The camera housing 66 has a processed coolant line 65 for circulating the coolant to prevent overheating, and a triangular prism 64 attached to the end of the camera housing 66 capable of refracting a 90 ° external image in the direction perpendicular to the camera. Heater replacement device of the pressurizer for nuclear power plant. The method of claim 1, The camera 61 is directed toward the end of the tungsten rod in the welding head 42, the special filter 63 is inserted into the center of the film paper to observe the ultra-high temperature welding arc, characterized in that inserted Heater replacement device for pressurizer for nuclear power plant.