JPH0539505Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is an article removal monitor that measures the surface contamination concentration of articles taken out from a controlled area such as a nuclear power generation facility, especially an upper or lower radiation detector. The present invention relates to a signal processing device provided to prevent a background count value from changing due to movement of any one of the signals.

(Prior Art) Conventionally, an article taking-out monitor includes radiation detectors provided on the upper side, side surface, and lower side of the article to be measured, and a detector that moves the upper radiation detector to approach the surface of the article, for example. It consists of a moving mechanism. The detection value detected by each radiation detector (detector) measures and displays the contamination concentration on the surface of the article.

(Problem that the invention aims to solve) However, in addition to the detected radiation emitted from the object, radiation from the surrounding atmosphere that affects the upper, side, and lower detectors is measured using the background (BG). That's what it means. When moving (lowering) the upper detector closer to the article surface, a shielding portion occurs in which a portion of the side detector is shielded by the upper detector. Moreover, a shielding portion occurs between the upper detector and the lower detector. For this reason, there was a problem in that the BG count value detected by each detector changed due to a change in the vertical position of the upper detector. The tendency of this change is that when the upper detector is lowered, the BG count value tends to decrease. Therefore, when measuring surface contamination of articles,
Since the BG count value changes depending on the position of the upper detector, that is, the height from the object, there was an important problem to be solved: accurate radiation measurements could not be made.

In view of the above-mentioned points, the present invention effectively solves the problems of the conventional technology, eliminates the change in BG count value due to the movement of the detector, improves measurement accuracy, and achieves accurate judgment of article removal. The purpose is to provide a monitor.

(Means for solving the problem) In order to achieve such an objective, the present invention
A signal processing device is provided that stores a change in the background count value of each of the detectors caused by movement of either the upper or lower detector, corrects the detection signal of the detector, and displays contamination on the measuring section. It is characterized by being prepared.

(effect) This signal processing device operates as follows.

By means of storing changes in the BG count value at the moving position of the detector,
Eliminates changes (decrease) in BG count values to enable accurate radiation contamination measurements.

(Example) Next, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention, where A is in its measurement standby state, B is in its measurement state,
FIG. 2 is a measurement block diagram of FIG. 1. In FIGS. 1 and 2, the article removal monitor 20 is
Mainly upper, side and lower detectors 1, 2,
3, a detector moving mechanism 4 for moving the upper detector 1 downward in this embodiment, a signal processing device 8, and a measuring section 11. The side detector 2 and the lower detector 3 are connected to this article taking-out monitor 2.
It is fixed to the main body of 0. Moreover, the upper detector 1 is
It is lowered by the detector moving mechanism 4 and approaches the article 5.

At this time, parts of the side detectors 2, 2, hatched areas a, a shown in FIG. 1, are portions that are shielded by the upper detector 1. Therefore, the side detectors 2, 2
BG count value changes. Furthermore, the distance between the upper detector 1 and the lower detector 3 is reduced. Therefore, the portion where the upper and lower detectors 1 and 3 shield each other also increases, the effective area for detecting the BG count value decreases, and the BG count value decreases.

The signal processing device 8 includes a calculation section 9, a determination section 10, and a storage section 12. The calculation unit 9 receives detection signals from the upper, side, and lower detectors 1 , 2 , and 3 via the scaler 6 . Along with this, the storage unit 12
stores the BG count value of each of the detectors 1, 2, and 3 by the article height detection device 7, and transmits it to the calculation unit 9. The calculation unit 9 operates on these detectors 1, 2, 3.
The detection signal is corrected and calculated using the stored signal in the storage section 12. The determination unit 10 determines the calculation result of the calculation unit 9 as an appropriate radiation contamination value, and causes the measurement unit 11 to display the contamination value.

Note that the detector moving mechanism 4 detects the height relative to the article 5 by the height detection device 7, and detects the height with respect to the article 5 using the signal processing device 8.
, the upper detector 1 is moved (lowered) to approach the article 5 .

(Effects of the invention) As explained above, according to the invention, changes in the background count value of each detector generated by a moving detector are memorized and the detection signal of each detector is corrected. By providing a signal processing device that performs calculations and displays contamination on the measurement unit, the problems of the prior art are effectively solved, and since the structure does not suffer from changes in the BG count value due to the movement of the detector, it is possible to Even though the height changes, accurate radiation contamination determination is always achieved, and there are effects such as preventing environmental contamination due to items being taken out.

In addition, in one embodiment of the present invention, a case will be described in which the upper detector moves and the lower detector is fixed, but the invention is not limited to this. It is also possible to have a function of correcting a change in the BG count value due to the lower detector rising with the article while the detector is fixed.

[Brief explanation of the drawing]

FIG. 1 shows a schematic diagram of an embodiment of the present invention, in which FIG. 1A shows an article waiting state, FIG. 2B shows an article measurement state, and FIG. 2 is a measurement block diagram of FIG. 1. 1...Top detector, 2...Side detector, 3...
Lower detector, 4...Detector moving device, 7...Height detection device, 8...Signal processing device, 9...Calculating unit,
10... Judgment unit, 11... Measuring unit, 12... Storage unit, 20... Item removal monitor.

Claims (1)

[Scope of utility model registration request] a plurality of radiation detectors arranged on the upper side, side surface and lower side of an article to detect the presence or absence of radiation contamination of the article, and moving either the upper side or the lower side of the radiation detectors to narrow the interval between them. A detector moving mechanism for moving the object closer to the object; an object positioning mechanism for detecting and positioning the distance between the object and the radiation detector using the detector moving mechanism; and a measuring section for measuring and displaying a measurement based on a detection signal from the radiation detector. In the article taking-out monitor, a change in the background count value of each of the radiation detectors caused by movement of either the upper radiation detector or the lower radiation detector is stored, and the detection signal is corrected to perform the measurement. 1. An article removal monitor comprising a signal processing device that displays a contamination indicator.