KR820001087B1 - Apparatus for the in situinspection of tubes while submerged in a liquid - Google Patents

Abstract

Arrangement is described for the inspection of the vertical coolant filled tubes (10) of a nuclear steam generator (1) which is out of service by drawing a sensor (34) attached to a cable (38) in and out of the tubes. Means are provided to remove coolant fluid from the cable being drawn out of the reactor to prevent the spread of contamination. Suitable means to remove the coolant include jets of compressed air. The recovered fluid is recycled to the reactor. The apparatus allows the tubes to be inspected without the need to drain away the primary coolant fluid.

Description

Customs inspection device for steam generator

1 is a cross-sectional view of the steam generator is installed.

2 is a partial cross-sectional view showing the structure of the surface moisture removing apparatus used in one embodiment of the present invention.

3 is a side view showing a cut away portion of an adjusting device used to adjust the position of the sensing element by means of a remote control on the customs to be inspected.

The present invention relates to a device for on-site inspection of the original condition of a plurality of tubes installed in the steam generator, in particular, the site of the original state of the customs while the customs of the steam generator is immersed in the primary coolant supplied from the reactor A device for testing is provided.

In general, such inspections are performed by passing a detector, such as a vortex sensor, into the tubules to produce an electrical effect that changes when any defect occurs in the tubules. This detector is connected to a flexible cable that makes an electrical connection to it and allows it to be moved within customs.

When the detector is pulled from the tubules at a constant rate, several feet per minute, eddy current data in analog form is collected by a receiver such as a magnetic tape or a strip chart recorder (digital). Before or during recording, this data is transformed into its horizontal and vertical components and converted into digital form to aid in the analysis of the data.

Safety inspections of the reactor facility are made during the operation of the reactor to periodically inspect the coolant circulated from the reactor for the original condition of the customs in the steam generator. This test is usually done during the reloading of fuel in the reactor.

Because of the presence of radiation in the reactor, it is necessary to transfer the spent fuel assembly to the fuel storage pool, replace it with a new fuel assembly, and then rearrange the fuel assemblies and control rods within the reactor core filled with primary coolant.

Because of the relative height of the reactor and the steam generator, the steam generator is partially filled with primary coolant upon refueling. The presence of the reactor coolant in the steam generator's tubing itself does not affect the vortex test, but the detector actuator that pulls the detector out of the tubing is wetted by the coolant, causes the cable to erode and further reduces the reliability of the data. will be.

In order to prevent the mechanical detector actuator from getting wet or contaminated with the reactor coolant, the primary coolant in the steam generator must be discharged before customs inspection. Even if the test method is fast, the steam generator can be operated for 3 days or 3 days and a half days. I had to stop about. Therefore, due to this problem, the actual utility value loss of the power generating unit amounted to $ 300,000 per day.

The object of the present invention is to reduce the downtime of the power generator in practice by inspecting the customs in the steam generator partially filled with the primary coolant in parallel with the refueling in the above state, by way of example drawing More detailed description is as follows.

1 shows a steam generator 1 in which a primary coolant is supplied from a reactor (not shown) through a nozzle 2 and a primary coolant is supplied to the reactor through the nozzle 4. It is formed to be discharged to recover. In addition, the steam generator 1 is provided with a water supply port 5 for water supply and a steam outlet 7 for discharging the generated steam.

In the steam generator 1, a plurality of tubules 10 are positioned by tube plates 6 and 8 and a general support plate body (not shown), through which primary coolant flows. This type of steam generator has up to 16,000 customs, up to approximately 1.56 centimeters in diameter, approximately 0.085 centimeters in wall thickness, and approximately 18.24 meters in length, and has three of the total customs selected according to a pre-determined pattern when reloading the fuel. The percentage is checked.

In FIG. 1, a single tube 10A is enlarged to clarify the description of the present invention. When reloading nuclear fuel, the hemispherical front part 12 of the steam generator is completely filled with primary coolant and the customs is partially filled with primary coolant up to the level determined by the relative height of the reactor and the steam generator.

A detector regulator 18 composed of an arm 22 and a servomotor 20 supported at the center of the steam generator through a passage 16 in the upper portion 14 of the steam generator during nuclear fuel reloading. Is installed, where the arm 22 is adapted to be rotated in a 360 degree direction. The carriage 24 supported by the arm by the roller 25 coupled to the guideway 21 on the arm 22 is connected to the servo motor 26 and the rack and pinion gear 28. Thereby moving forward and backward along the arm from the center of the steam generator and moving in a radial direction. At the lower end, a fixture 27 receiving the guide tube 29 having a bell-shaped inlet 33 and a gooseneck tube 32 at its upper end is fixed to the carriage 24 in a detachable manner. Thus, by operation of the servo motors 20, 26, the bell-shaped inlet 33 can be carried in accordance with any of the customs 10 selected for inspection.

The tubule 10A is described as an example, and the detector 34 is an electrical conductor inserted into the flexible conduit 40 to a drive 36 actuated by a motor capable of reversing the cable 38 connected thereto. By releasing it, it can be sent down the predetermined length within customs. After the detector has reached the predetermined length, the drive 36 rotates in reverse to draw the detector from the customs at a constant speed.

During the pull up, the electrical signal generated by the detector is transmitted to a device installed for analysis.

The control device for adjusting the analysis device and the servo motors 20 and 26 and the driving device 36 may be installed far from a dangerous place around the steam generator for its convenience and safety.

As shown in FIG. 1, the surfaces of the detector 34 and the cable 38 are wetted with primary coolant in the tubule 10A. Surface to allow the coolant on the surface of the cable 38 to be recovered and sent to the steam generator to prevent primary coolant on the cable 38 from interfering with the drive 36 and contaminating the steam generator. A moisture removal device 42 is installed in the flexible 40 between the gooseneck tube 32 and the drive device 36.

Thus, the cable 38 is treated to be dry and free from contamination before passing through the drive device 36.

As shown in FIG. 2, the surface moisture removing device 42 has an inner tube portion 46 having an axial passage 47 extending through the cable 38 and in communication with the conduit 40. As shown in FIG. The cylindrical housing 44 is comprised. The flange 50 of the inner tube portion 46 forms a plenum chamber 52 capable of hermetically supplying a drying medium such as air having a pressure associated with the inlet opening 48. The O-ring gasket 51 is inserted. The drying medium is discharged from the plenum chamber 52 to the passage 47 through which the cable 38 passes through the outlet port 54. The outlet port 54 is formed at an acute angle with respect to the center line of the passage 47 so that the drying medium can be sprayed onto the cable 38 to dry the coolant on the surface of the cable 38.

All coolant removed from the cable 38 is discharged to the steam generator 1 through the bell inlet 33 along the air flow in the conduit 48, and the coolant collected in the passage 47 is discharged ( 56 and the discharge line 58 is recovered to the steam generator (1). In addition, the surface moisture removing device 42 is provided with a nipple 57 in which the conduit 40 is welded, and a baffle 60 so that the drying medium does not flow in an opposite direction that is not required.

Claims (1)

A device for inspecting the original state of customs while these customs contain the reactor coolant in the steam generator (1) of the nuclear power plant, which allows the reactor coolant to flow through a plurality of vertical customs (10) with open top and bottom ends. In this case, the detector 34 is introduced into the customs, the cable 38 is connected to the detector, and at the same time it is connected to the drive 36 located remotely from the steam generator customs, between the drive and the customs to be inspected. The conduit 40 surrounding the cable in the form a bell-shaped open end 33 which is aligned with the open upper end of the tubule, and the dehumidifier 42 is the drying medium while the drive pulls the detector through the tubule. A customs inspection device for a steam generator that introduces a flow of gas into a conduit adjacent to a driving device and discharges a drying medium through an open end of the conduit.

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