JP4155523B2 - Article removal monitoring device - Google Patents

Description

  The present invention relates to an article carry-out monitoring device that inspects the presence or absence of contamination by radioactive substances on the surface of a carry-out article when carrying out an article used in a nuclear facility from a radiation control area to a non-control area.

  In a nuclear facility such as a nuclear power plant, articles such as scaffolding plates and pipes used for construction, or tools, instruments, clothing, etc. used for work in radioactive control areas are made of radioactive materials. There is a possibility of contamination.

In order to prevent these items contaminated with radioactive materials from being taken out of the radioactive controlled area when they are carried out to the non-radioactive controlled area, the articles to be carried out (hereinafter measured) It is necessary to inspect for contamination by radioactive materials.
Conventionally, an article carry-out monitor device is provided as a device for performing such an inspection.

  As a conventional article carry-out monitoring device, a conveying device such as a belt conveyor that conveys an object to be measured to be inspected for contamination by a radioactive substance in the horizontal direction is provided, and a plurality of items are arranged along the conveying direction of the conveying device. The radiation detectors of the table are arranged and fixed side by side.

  Then, the object to be measured is conveyed and moved into the monitor device by the conveying device, and when the object to be measured passes through the position where the radiation detector is provided, the surface of the object to be measured or a part of the object is measured by the radiation detector. It is configured to measure the amount of radiation that is attached to and to detect the presence or absence of contamination by radioactive substances.

  However, in such an article carry-out monitor device, when the contaminated area of the measurement object to be inspected is larger than the size of the radiation detector, the radiation count value decreases with only one radiation detector, and the measured object There are cases where radiation contamination of objects cannot be detected.

In such a case, an article carry-out monitor device as shown in FIG. 5 has been conventionally considered.
That is, in FIG. 5, 1 is a conveying device such as a belt conveyor, 2 is a driving device of the conveying device 1, 3 is an object to be measured conveyed by the conveying device 1, 4 is a radiation contamination region of the object to be measured 3, S1, S2,... Sx,... Sn are a plurality of radiation detectors arranged along the transport direction of the transport device 1 so as to cover the size of the largest object to be measured and to cover it. 5 is a signal processing device to which detection outputs from the plurality of radiation detectors S1, S2,... Sx,... Sn are input, and 6 is a computer to which signals from the signal processing device 5 are input (for example, (See Patent Document 1).

In such an article carry-out monitor device, when the size of the object to be measured 3 cannot be covered by one radiation detector S, the radiation dose of the object to be measured 3 is detected by the adjacent radiation detector S. Then, by adding and measuring the outputs of the adjacent radiation detectors S, the radiation amount of the object 3 to be measured is compensated for by the decrease in the count value per radiation detector and the decrease in the S / N ratio. I try to detect it.
On the other hand, although it is conceivable to manufacture the radiation detector S with a sufficiently large dimension, it is difficult to manufacture a detector having a large area and there is a possibility that the handling operation may be difficult.
Japanese Utility Model Publication No. 3-55111

  In the above-described conventional article carry-out monitor device, the measurement object 3 is large, and when the detection is performed by a large number of radiation detectors S1, S2,... Sx,. All of the radiation detectors S1, S2,... Sx,... Sn are moved, and the radiation dose is detected by all the radiation detectors S1, S2,. It shifts in order along the movement of the measurement object 3.

  The detection timings of the adjacent radiation measuring instruments S can be synchronized and the outputs can be added. However, since the detection timings of the radiation detectors S arranged at distant positions are shifted, all the radiation detectors S1 and S2 are detected. ,... Sx,... Sn are not added.

For this reason, it is difficult to accurately measure the radiation dose, and it is difficult to accurately identify the contaminated area of the object to be measured.
In addition, since accurate measurement is difficult, the radiation dose detection processing takes more time than necessary.

  The present invention has been made to solve the above-described problems, and can measure the radiation dose of the object to be measured accurately in a short time, and can easily identify the radiation-contaminated region of the object to be measured. It is an object to obtain an article carry-out monitor device.

In order to achieve the above object, the invention according to claim 1 is arranged side by side along a transport direction of a transport device that transports a measurement object to be inspected for contamination by radioactive substances. A plurality of radiation detectors for sequentially counting the amount of radiation of the object to be measured conveyed by the conveying device, and a loading side of the conveying device, and the object to be measured is placed at a predetermined position on the loading side of the conveying device. A first position detector that detects that the object has reached, and a second position detector that is provided on the carry-out side of the transfer device and detects that the object to be measured has reached a predetermined position on the carry-out side of the transfer device And the object to be measured is transported by a transport device, and the sampling time is from the detection time of the first position detector to the detection time of the second position detector, and each of the radiation detectors at the sampling time is the count value Sn based on Characterized by comprising a stomach count value Ci (t) and a computer for calculating the sum by the following equation.
Ci (t) =
(N′d−vt + d) / d × Sn′−i (t) + (vt−n′d) / d × Sn ′ + 1−i (t)
However, i is 1 to n (n is the number of radiation detectors), n ′ = MOD (vt / d) (MOD = value of an integer part when divided), d is a width dimension of the radiation detector, and v is Transport speed, t is sampling time, Sn is a count value of the nth radiation detector.

  According to the article carry-out monitor device according to the present invention, the radiation dose of the object to be measured can be accurately measured in a short time, and the radiation-contaminated region of the object to be measured can be easily identified.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiment, the same parts as those in the conventional article carry-out monitoring apparatus shown in FIG.

  1 and FIG. 2B, S1, S2,... Sx,... Sn are a plurality of radiation detectors arranged in a line along the transport direction of the transport apparatus 1, and 7a is an article entrance of the transport apparatus 1. A first position detection device such as a photoelectric switch provided on the side (loading side), for example, 7b is a second position detection device provided on the article outlet side (unloading side) of the transport device 1, The position detection signal is input to the computer 6.

  8 is provided at a position separated from the position where the first position detector 7a is provided by the dimension L along the conveyance direction, and images an image of the measurement object 3 conveyed by the conveyance device 1, An imaging device such as a camera for inputting image signals to the computer 6, and a display device 9 connected to the computer 6.

Next, the operation of this embodiment will be described.
In FIG. 1, an object to be measured 3 is placed on a transport device 1, moves at a transport speed v in the direction indicated by an arrow, and is transported into a monitor device.

A plurality of radiation detectors S 1, S 2,... Sx,... Sn provided along the transport device 1 sequentially count the radiation dose as the measured object 3 passes through the radiation contamination region 4.
Detection signals counted by the respective radiation detectors S1, S2,... Sx,... Sn are input to the signal processing device 5, and each radiation detector S1, S2,. ... the count value of Sn is transmitted to the computer 6 and added.

  During the predetermined time (sampling time t), the first position detector 7a detects that the object to be measured 3 has reached a predetermined position on the entrance side of the transport apparatus 1, and transmits the detection signal to the computer 6. In the computer 6, the second position detector 7b detects that the object to be measured 3 has reached a predetermined position on the exit side of the transport device 1 with the time as the origin, and until the detection signal is received. Let time be the sampling time t.

Based on the sampling time t, the computer 6 adds the count values of the radiation detectors S1, S2,... Sx,... Sn according to the following equations (1) to (3).
Here, the count value of each radiation detector S is C (t), the detector width dimension along the transport direction of the radiation detector alone is d, and the transport speed of the transport device is v .

The count value of the first radiation detector S1 is C1, and the count value of the first radiation detector S2 is C.
2. If the count value of the i-th radiation detector Si is Ci,
C1 (t) =
(N′d−vt + d) / d × Sn′−1 (t) + (vt−n′d) / d × Sn ′ (t) (1)
C2 (t) =
(N′d−vt + d) / d × Sn′−2 (t) + (vt−n′d) / d × Sn′−1 (t) (2)
Ci (t) =
(N′d−vt + d) / d × Sn′−i (t) + (vt−n′d) / d × Sn ′ + 1− i (t) (3)
Here, n ′ = MOD (vt / d)
(MOD = value of the integer part when dividing)
In the above-described addition of the count value C, it is expressed as if the object to be measured 3 is fixed at the same position for the entire time on the transport device 1.

  In the calculator 6, the count value C of each radiation detector S1, S2,... Sx,... Sn is added until the time t = t0 when the DUT 3 passes through the last radiation detector Sn by the second position detector 7b. Then, as shown in FIG. 3 (a), on the display device 9, the count value C of each radiation detector S is set to a count value (C1, C2, C3, For example, Cn) is green, the count value (Cn-2) exceeding a predetermined value is red, the intermediate count value is (Cx, Cn-1) is yellow, and the contamination distribution is displayed one-dimensionally. Is displayed, it is determined that the object to be measured 3 is contaminated with a radioactive substance, an abnormal alarm signal is generated, and a radiation-contaminated area is specified by color display on the display device.

Alternatively, instead of specifying the contaminated area by color display as described above, image processing may be performed on a bar graph or the like to express it primarily.
In such an article carry-out monitor device according to the present embodiment, even when the dimension of the object to be measured 3 to be inspected is larger than the size of the radiation detector alone, it is aligned in a line along the transport direction of the transport device 1. Since the count values of the plurality of arranged radiation detectors S1, S2,... Sx,... Sn are all added, accurate radiation dose measurement can be performed in a short time.
Further, since the count values of the radiation detectors S1, S2,... Sx,... Sn are displayed on the display device, it is possible to easily identify the radiation contamination area of the object to be measured 3.

Next, a second embodiment of the present invention will be described.
Also in FIG. 1, the first position detector 7 a detects the time when the DUT 3 starts to pass through the first position detector 7 a and the time when it passes through and inputs the detected time to the calculator 6.
Further, the transport speed v of the transport device 1 is input from the drive device 2 to the computer 6.

  The calculator 6 calculates the time when the DUT 3 starts to pass through the first position detector 7a and the time interval Δt at the end of passing, and this value and the unloading speed v of the transport device 1 by the driving device 2; From the distance (L) between the first position detector 7 a and the camera 8, the time T at which the center of the DUT 3 passes the position of the camera 8 is calculated by the following equation (4).

T = (L−0.5 × v × Δt) (4)
The computer 6 issues a command to the camera 8 at the timing of the time T, takes an image of the device under test 3 and extracts an image signal.

As shown in FIG. 4B, the image signal of the object to be measured 3 by the camera 8 and the image of the contamination distribution of the object to be measured 3 described in the first embodiment are combined. By expressing the contaminated area 4 in a screen display such as an ellipse, it is possible to visually identify the contaminated area.
In FIG. 4A, the contaminated area is represented by an ellipse, but the present invention is not limited to this.
Thus, by visually representing the contaminated area 4, the contaminated area can be identified more easily.

Next, a third embodiment of the present invention will be described.
In the present embodiment, as shown in FIG. 2B, FIG. 3B, and FIG. 4B, the radiation detector S is moved along the transport direction of the transport device 1 and substantially perpendicular to the transport direction. A plurality of rows may be arranged in the intersecting direction and arranged two-dimensionally.

  With this arrangement of the radiation detector S, the radiation dose C is also counted two-dimensionally, and an image of the two-dimensional radiation-contaminated region 4 of the object to be measured 3 is obtained. Can be accurately identified.

The schematic front view which shows the structure of the goods carrying-out monitoring apparatus by the 1st and 2nd embodiment of this invention. It is a schematic plan view which shows arrangement | positioning of the radiation detector in the goods carry-out monitor apparatus by embodiment of this invention, (a) is based on 1st Embodiment, (b) is based on 3rd Embodiment. It is a schematic plan view which shows the radiation contamination distribution display in the article delivery monitor apparatus by embodiment of this invention, (a) is based on 1st Embodiment, (b) is based on 3rd Embodiment. It is a schematic plan view which shows the radiation contamination distribution display in the goods carry-out monitor apparatus by the 2nd Embodiment of this invention, (a) is based on 1st Embodiment, (b) is based on 3rd Embodiment. thing. The schematic front view which shows the structure of the conventional article carrying-out monitor apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conveyance apparatus, 2 ... Drive apparatus of conveyance apparatus, 3 ... To-be-measured object, 4 ... Radiation contamination area | region of to-be-measured object 3, S1, S2, ... Sx, ... Sn ... Radiation detector, 5 ... Signal processing apparatus, 6 ... calculator, 7a ... first position detector, 7b ... second position detector, 8 ... photographing device, 9 ... display device.

Claims (7)

A transport device that transports a measurement object to be inspected for contamination by a radioactive substance, and a radiation device that is arranged side by side along the transport direction of the transport device and that is transported by the transport device is sequentially counted. A plurality of radiation detectors; a first position detector that is provided on the carry-in side of the transfer device and detects that the object to be measured has reached a predetermined position on the carry-in side of the transfer device; and A second position detector that is provided on the carry-out side and detects that the object to be measured has reached a predetermined position on the carry-out side of the conveying device; and the object to be measured is conveyed by the conveying device, and the first position The sampling time from the detection time of the detector to the detection time of the second position detector is used as a sampling time, and the count value Ci (t) is calculated by the following equation based on the count value Sn of each radiation detector at this sampling time. Calculation to add Consisting of an article carry-out monitoring device.
Ci (t) =
(N′d−vt + d) / d × Sn′−i (t) + (vt−n′d) / d × Sn ′ + 1−i (t)
However, i is 1 to n (n is the number of radiation detectors), n ′ = MOD (vt / d) (MOD = value of an integer part when divided), d is a width dimension of the radiation detector, and v is Transport speed, t is sampling time, Sn is a count value of the nth radiation detector.   2. The article carry-out monitor device according to claim 1, wherein the plurality of radiation detectors are arranged in a line along the transport direction of the transport device and are arranged one-dimensionally.   The article according to claim 1, wherein the plurality of radiation detectors are arranged in a two-dimensional manner in a plurality of rows arranged in a direction substantially perpendicular to the transport direction along the transport direction of the transport device. Unloading monitor device.   4. The display device according to claim 1, further comprising: a display device that displays a radiation dose count value of the plurality of radiation detectors on a screen and displays a distribution of radiation contamination of the object to be measured. Goods carry-out monitor device.   5. The article carry-out monitor device according to claim 4, further comprising a photographing device for photographing an image of the object to be measured and extracting an image signal of the object to be measured.   Combining a screen for displaying the radiation dose count values of the plurality of radiation detectors and an image signal from the imaging apparatus, and displaying a screen for specifying a radiation contamination area of the object to be measured on the display device; 6. The article carry-out monitoring device according to claim 5,   The timing at which the measurement object is imaged by the imaging apparatus is determined with respect to the time interval between the time when the measurement object starts to pass through the first position detector and the time when the measurement object passes and the conveyance speed of the conveyance device. The article carry-out monitor device according to claim 5, wherein the article carry-out monitor device is calculated from the distance between the first position detector and the photographing device.

Images