JPH02115785A - Contamination monitoring device - Google Patents

Abstract

PURPOSE:To improve the measuring performance of a contamination monitoring device with a simple constitution by covering or wrapping an object to be measured with a cloth-like scintillator member and counting light emitted when a radioactive contaminating substance adhering to the object is made incident on the cloth-like member. CONSTITUTION:An object 1 to be measured and cloth-like scintillator member 2 are housed in a dark room 3 and plural light guides 92 and plural photodetectors (photoelectric multipliers) 7 are arranged on inner walls of the dark room 3. When the object 1 is covered or wrapped with the cloth-like member 2, the distance from a radioactive material 4 adhering to the object 1 can be reduced within about 5cm or shorter being the range of alpha rays. Radiation 5 radiated from the material 4 is detected by the member 2 which converts the radiation 5 into light 6. The light 6 are led to the photodetectors 7 by the light guides 92 and the photodetectors 7 count the light 6. An arithmetic circuit 8 performs arithmetic operations on the counted results and displays the results. Therefore, alpha rays having a short range can be detected easily from an object 1 to be measured having an uneven surface.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a contamination monitoring device for measuring the concentration of contamination by radioactive contaminants on the surface of an object to be measured in a nuclear power station or a radioactive material handling facility. .

(Prior Art) Conventional dyeing monitor devices include a gas flow system that detects β-rays or gamma-rays emitted from the surface of the object to be measured, in order to measure the concentration of radioactive contamination on the surface of the object. Large, flat radiation detectors such as detectors or plastic detectors were used. FIG. 2 does not show a schematic tree diagram of a conventional contamination monitoring device.

In the figure, a contamination monitoring device 20 is composed of a large flat radiation detector 9, a shield 10 that blocks the infiltration of external radiation, and an object 1 to be measured installed within the shield 10. The QJFA detector 9 includes a scintillator 91, a photodetector (photomultiplier tube) 7, and a light guide 92. Furthermore, 4 is a radioactive substance attached to the surface of the object to be measured 1, and 5 is a line a=J ray emitted from this radioactive substance.

(Problem to be Solved by the Invention) However, when the surface of the object to be measured 1 has severe irregularities, the flat plate-like t! l! ) The J-ray detector 9 is brought as close to the object to be measured 1 as possible to shorten the distance to the object to be measured 1, but due to the unevenness of the object to be measured 1, it is difficult to get closer than a certain distance. It is n. For this reason, unlike beta and gamma rays, which have a long range, alpha rays, etc., have a short range.
There was a problem in that the light did not reach the one-line detector 9, making it difficult to detect it.

In view of the above-mentioned points, it is an object of the present invention to provide a contamination monitoring device that effectively overcomes the problems of the prior art, has a simple configuration, and has improved measurement performance.

(Means for solving the problem) In order to achieve such an object, the present invention provides a scintillator cloth member formed in a cloth shape and provided so as to cover or wrap around an object to be measured; A dark room that accommodates this scintillator cloth member and the object to be measured, and a dark room that is arranged on the inner wall of this dark room to count the light emitted when the radioactive contaminants of the object to be measured enter the scintillator (B-shaped member). It is characterized by comprising a photodetector and an arithmetic circuit that processes and displays the output of the photodetector.

(Function) With the technical means configured as described above, the scintillator cloth member covers or wraps around the object to be measured and comes close to or close to the object to be measured, thereby reducing the short range α. It becomes possible to sufficiently detect lines, the configuration is simple, and the detection performance is improved.

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

FIG. 1 is a schematic diagram of an embodiment of the present invention.

In the figure, parts having the same filtering performance as in FIG. 2 are given the same reference numerals. The contamination monitoring device 30 mainly includes an object to be measured 1 and a scintillator cloth-like member 2, a darkroom 3 that accommodates the object to be measured 1 and the scintillator tie-like member 2, and a plurality of lights arranged on the inner wall of this darkroom 3. It is composed of a guide 92, a plurality of photodetectors 7, and an arithmetic circuit 8 for processing the output of the photodetectors 7. 6 is light emitted from the scintillator cloth member 2.

This scintillator cloth-like member 2 is made of scintillation fibers etc. woven into a cloth shape, or a glass scintillator etc. woven into a cloth shape like a normal glass Iff, or a plastic scintillator etc. cut into small pieces and has flexibility. It is formed into a cloth-like shape by joining them together with adhesive or the like.

Therefore, this scintillation section 442
By covering or wrapping the object 1 to be measured, it is easy to bring the object 1 close to or close to the radioactive substance 4 at a distance 5k within approximately 5 cm, which is the range of alpha rays. Note that the photodetector 7 is a 10 g photomultiplier tube placed on the inner wall of the lla chamber 3 in this embodiment.

With this configuration, the IJ=J rays 5 emitted from the radioactive substance 4 attached to the object to be measured 1 are detected by the scintillator cloth member 2 and converted into light.

This light is guided by a light guide 92 to a photodetector 7 arranged on the inner wall of the dark room 3, counted by the photodetector 7, processed by an arithmetic circuit 8, and displayed.

That is, the radiation IEI 5 is converted into light very close to the radioactive substance 4, and by counting this light with the photodetector 7, it is possible to detect α-rays with a short range even though the object to be measured 1 has unevenness. etc. becomes easy to detect, and its measurement performance improves.

(Effects of the Invention) As described above, according to the present invention, there is provided a scintillator cloth member formed in a cloth shape and provided so as to wrap around an object to be measured, and a scintillator cloth member and the object to be measured. a photodetector disposed on the inner wall of the darkroom for counting the light emitted when the radioactive contaminant of the object to be measured enters the scintillator cloth member; The arithmetic circuit that performs arithmetic processing and display effectively solves the problem of conventional technology, which makes it difficult to detect alpha rays from objects with large irregularities.The structure is simple and the measurement performance is improved. It has effects such as:

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram of a conventional contamination monitoring device. 1: object to be measured, 2: scintillator cloth member, 3: darkroom,
4: Radioactive substance, 7: Photodetector, 30: Contamination monitoring device. Patent applicant Fuji Electric Hou Co., Ltd.

Claims (1)

[Claims] 1) In a contamination monitoring device that measures the concentration of contamination by radioactive contaminants on the surface of an object to be measured, a scintillator cloth-like member formed in a cloth shape and provided to cover or wrap the object to be measured. a dark room that accommodates the scintillator cloth member and the object to be measured; and a dark room that is arranged on the inner wall of the dark room to count the light emitted when radioactive contaminants of the object to be measured enter the scintillator cloth member. What is claimed is: 1. A contamination monitoring device comprising: a photodetector; and an arithmetic circuit that arithmetic processes and displays output from the photodetector.