HUT69275A - Sensing probe - Google Patents

Abstract

The invention relates to a sensing probe for examining the local corrosion state of inner tube surfaces, which comprises a radiation source (6) emitting electromagnetic radiation, a radiation detecting means (7), built into the same structural unit as the radiation source, measuring the irradiation reflected from the inner surface to the tube, and an element (3) arranged between the radiation source (6) and the detecting means (7), the said element (3) being opaque for the irradiation, wherein the wavelength of the said electromagnetic radiation emitted by the radiation source (6) is chosen in the range where the intensities of the irradiation reflected from the bare metal and from the corroded surface are different. Furthermore, the invention relates to a method for examining the local corrosion state of inner tube surfaces.

Description

BACKGROUND OF THE INVENTION The present invention relates to a sensor probe for detecting an internal surface condition of tubes, characterized in that it comprises a radiation source emitting electromagnetic radiation, an integrated radiation detector detecting radiation reflected from the inner surface of the tube, and a non-transmissive electromagnetic radiation and a measurement procedure with the above probe.

The sensor probe of the present invention is preferably used in nuclear reactors to test the corrosion of the cooling pipes in the primary circuit heat exchanger of the nuclear reactor.

It is a prerequisite for the safe operation of nuclear reactors that radioactive materials cannot be released into the environment through corrosion of structural materials. In pressurized water reactors, so-called nuclear fission is heated. it is utilized by the primary water of the water in the waiting water placed in the secondary water circuit. The heat exchangers between the primary and secondary water circuits are one of the most dangerous parts of power plants in terms of corrosion, because of the high flow velocities and large temperature differences.

Radioactivity from the primary circuit to the secondary circuit can be measured by tracer techniques (see, for example, DE 2,810,699), but these procedures do not predict tube wall faults, provide no cause for leakage, or provide heat exchangers. not applicable.

The need for corrosion testing of heat exchanger tubes is underlined by the fact that in practice,

No methods have yet been developed for the direct investigation of the effects of coenzyme inside the heat exchanger tubes of nuclear reactors.

or, indirectly, as a general rule

The first method is to determine what changes have occurred *

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One group of procedures is based on the measurement of (ultra) sound. It is sensed (see, for example, DE 3,131,883). The results of the measurements give information about the Eanees wall thickness and whether there is a crack in the wall. However, the condition of the surface of the pipe wall is not directly attributable to the process of winter change.

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136). The methods of this invention are to induce a current in the magnetic field in metals and thus to produce a magnetic field.

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provide information about your average condition.

There is widespread use of mechatical methods.

Some of them use a video camera (see GB 2 242 497) or take photographs of the surface of the tubes (see EP 282 687) and visually detect changes in the tube. The disadvantage of the method is that it does not allow for simple, fast but at the same time quantitative data evaluation methods. Light reflection based on <99 ··

- 5 tube screening methods, including high-volume instrumentation,

1VS to the tube annulus and their resonance measured with fiberglass optics maximize release,

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The object of the invention is, on the one hand, to display the surface state of the zalaxalosanda zscvar of Zala, characterized by ^ -LSX'C ^ TOiucicneseS SUC £ r2dSt AlphocosSsC SUgS-OL, 3Z Z S.J.

a unit comprising a radiation detector for reflecting radiation from the inner surface of the tube and an element impermeable to electromagnetic radiation emitted between the two.

The invention further relates to a method for testing the surface conditions of tubes by applying electromagnetic radiation to the inner surface of the tube and detecting reflected radiation by a radiation detector which is sealed off ^from primary radiation.

When a sensor probe as defined above is preferably used, surface corrosion is determined by locally emitting a small annular portion of the inner surface of the tube to be tested and measuring the reflected radiation near the source but well spaced from the direct primary radiation. The intensity of the reflected radiation characterizes the state of the surface in terms of corrosion. Repeating the measurement parallel to the longitudinal axis of the tube at several discrete points, or continuously measuring, gives quantitative data on the corrosion state of the tube generally and locally.

The measured intensities can also be processed and stored by computer, enabling

- proper probe calibration,

- regular monitoring of oso status.

- graphical evaluation of intensities by tube length dependence:

- determining trends over time and thus eliminating the dangerously corroded tube from the heat exchanger.

The preferred embodiment of the sensor probe according to the invention includes the following:

(a) a tube with openings cut in such a way that radiation exiting the radiation source can escape from the tube or reflected radiation can enter the tube;

b) an impermeable element, preferably a disc, which divides the tube into two portions perpendicular to its longitudinal axis;

(c) a source of radiation incorporated in a part of the tube by a soluble or insoluble bond;

(d) a beam detector fitted to the other part of the tube with a soluble or insoluble bond.

The wavelength range of the radiation emitted by the radiation source must overlap the wavelength range at which the reflection of the metal, especially steel, and the oxide layer formed on its surface can be clearly distinguished. In addition, the size and availability of the radiation source are crucial. Based on all these, it is most expedient to use a radiation source within the visible range, e.g. use a light bulb or light emitting diode (LED). They are inexpensive, readily available commercially and do not require any maintenance. In addition, UV sources, in particular discharge tubes, may be used, but these must be individually tailored to the particular need or to ZR as a source.

It is advisable to use a photodiode as a radiation detector. Depending on the wavelength range of the light to be measured, the device contains semiconductors of different material quality, the electrical conductivity of which varies with the intensity of the illuminating light and can be detected in the form of a change in intensity - a change in voltage. The great advantage of photodiodes is that they are small, inexpensive and also maintenance-free.

In a preferred embodiment of the sensor probe according to the invention visible light is used, more preferably white light, whereby the light source is preferably an incandescent lamp and the detector is a visible light detecting diode.

In Figure 1, parts of a preferred embodiment of the preferred embodiment of the invention, operating in the visible light region, are described below.

a stainless steel tube 1 with four openings 2 cut in such a way that each opening forms a stadium curve parallel to the longitudinal axis X of the tube 1 and spaced evenly along the periphery of the tube 1;

a light-impermeable disk 3, preferably made of plastic, which divides the tube 1 into two equal portions 4,5, perpendicular to the longitudinal axis X;

a light source 6 inserted into a portion 4 of the tube 1 with a soluble or insoluble bond;

and a photodetector 7 inserted into the other part 5 of the rain with a suitable size soluble or insoluble bond;

the DC voltage required for the operation of the 6 light sources and the signal measured by the photodiode are switched on and off. and a rigid cable 3 for moving the probe (the cable consists of a 10-wire wire wrapped around a steel wire 9 and a plastic cover 11 surrounding it, and the wire 9 is spot-welded to the pipe 1 to provide electrical ground), two opposing plastic skirts 12 holding the tube 1 in the longitudinal axis of the tube to be tested (the skirts are secured to the stainless steel tubes 13, 14 and the latter tubes are connected by helical springs 15 to ensure that the tubes are bent into the probe) also able to progress);

a conical shaped solid plastic nose 16 secured to a steel tube 14 holding one of the skirts (this ensures safe passage of the probe);

an outer plastic cover which is secured to the end of the steel tube 13 supporting the other skirt with a non-slip surface finish.

Preferably, the sensor probe of the present invention is sized such that it can be connected to manipulators commonly used inside nuclear reactors and can travel unobstructed in the tubes being tested.

The probe shall be calibrated on specimens of known reproducible surface prior to measurement.

The signal measured by the probe may be stored and processed by computer. This makes it possible to monitor the corrosion processes and to compare the different pipes quantitatively. In computer signal processing, it is essential to standardize the measured signals with calibrated luminous intensity values and to store the results obtained under the conditions of measurement. Sz allows quantitative comparisons of data series. It is advisable to reduce the noise of the measured data by a properly chosen mathematical procedure and smooth the data series. The chemical information can then be separated from the measurement inaccuracy. The evaluation can be done graphically by plotting the tube length dependence of the luminous intensities or by jointly processing time-separated measurements, plotting the intensity of light reflected from a given point on the wall. All of these can also be given in percentage form.

The solutions detailed above apply mutatis mutandis if no visible light is used during the measurement.

Claims (11)

Claims A detecting probe for indicating the internal surface condition of tubes, characterized in that the radiation source (6) emitting electromagnetic radiation, a radiation detector (7) receiving radiation reflected from the inner surface of the tube, and an emitter radiation arranged between the two contains an impervious element (3). Sensor according to claim 1, characterized in that the radiation source (6) emits a visible light, 3. The sensor of claim 1, wherein said radiation source emits white light. Sensor according to Claim 3, characterized in that the radiation source (6) is an incandescent lamp. 5. A serine sensor according to any one of claims 1 to 4, characterized in that the radiation sensor (7) is a photodiode detecting visible light. 6. Sensor according to any one of claims 1 to 3, characterized in that the element (3) impermeable to electromagnetic radiation is a plastic disk. 7. A method for examining the surface conditions of tubes, characterized in that electromagnetic radiation is emitted to the inner surface of the tube and reflected radiation is detected by a radiation detector sealed against primary radiation. 8. The method of claim 7, wherein said light is electromagnetic radiation. 9. The method of claim 7, wherein the electromagnetic radiation is white light. 10. A serine method according to any one of claims 1 to 5, characterized in that the radiation detector is a photodiode detecting visible light. 11. A method according to any one of claims 1 to 3, characterized in that the radiation sensor is closed with a plastic disk from the primary radiation. 0 -y