JPH074619Y2 - Fluorescent glass dosimeter - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent glass dosimeter for measuring the radiation dose in the surrounding environment such as a nuclear power plant.

[0002]

2. Description of the Related Art In general, a fluorescent dosimeter glass element made of phosphate glass containing silver ions is used as a fluorescent glass dosimeter. This glass element emits fluorescence when excited by ultraviolet rays having a wavelength of 300 to 400 nm after being activated by exposure to radiation. Since the fluorescence intensity at this time is proportional to the radiation dose, it is possible to measure the radiation dose by detecting this fluorescence intensity.

In the measurement of such radiation, the light projected from the ultraviolet excitation light source is passed through an optical filter to selectively extract the ultraviolet light of a predetermined wavelength,
It is incident on one surface of a rectangular parallelepiped glass element almost vertically. Here, the glass that receives ultraviolet rays of a predetermined wavelength emits fluorescence, and the fluorescence emitted at this time is taken out from the direction perpendicular to the incident direction of the ultraviolet rays and the light in the predetermined wavelength range is passed through the optical filter. After that, photoelectric conversion is performed by a photomultiplier tube to obtain an electric signal having a level substantially proportional to the fluorescence intensity, and the fluorescence intensity, and thus the radiation dose, is measured from the level of this electric signal.

[0004] Conventionally, when measuring the cumulative radiation dose in the surrounding environment such as a nuclear power plant, the fluorescent glass dosimeter (hereinafter simply referred to as a dosimeter) is fixedly installed at each point to be measured for a certain period, The radiation dose was measured during that period.

[0005]

When the dosimeter is fixed as described above, since the dosimeter has a directional characteristic, the sensitivity to radiation from a specific direction, for example, radiation from 90 degrees to the left and right from the front, becomes low. Therefore, it may not be possible to measure the radiation dose with high accuracy, and it may not be possible to detect a small amount of radiation or radiation dose from facilities that handle radiation or business establishments.

Further, when a plurality of dosimeters are installed at one monitoring point, there is a problem that the measured values vary widely among the dosimeters due to the shielding effect between the dosimeters. .

The present invention, when performing environmental monitoring,
It is possible to reduce the occurrence of errors due to the radiation incident direction from the environment at the measurement point, to measure a small amount of leakage radiation at a natural level, and when multiple dosimeter samples are installed, It is an object of the present invention to provide a fluorescent glass dosimeter capable of measuring with a small variation in.

[0008]

SUMMARY OF THE INVENTION According to the present invention, at least one glass element that emits fluorescence when excited by ultraviolet rays after being activated by exposure to radiation is placed on a gantry installed at a position where radiation dose is to be measured. The monitoring container for housing or the glass element is rotatably supported.

[0009]

In the present invention, since the glass element or the monitoring container accommodating the glass element is configured to be rotatable, it is possible to reduce the occurrence of an error due to the radiation incident direction from the environment at the measurement point during environmental monitoring. Therefore, it is possible to measure a very small amount of leakage radiation at a natural level.

[0010]

Embodiments of the present invention will be described below. FIG. 1A is a block diagram showing a part of an embodiment of a fluorescent glass dosimeter according to the present invention. Lower horizontal mounting portion 1a included in the gantry 1 installed at a desired position for measuring radiation
The bearing 2 is vertically mounted on the bearing 2, and the rotary shaft 3 is rotatably provided on the bearing 2. A monitoring container 4, which will be described later, is connected to the lower end of the rotating shaft 3. Further, the rotary shaft 5a of the motor 5 is mounted vertically on the upper horizontal mounting portion 1b of the gantry 1, and the rotary shaft 5a of the motor 5 and the rotary shaft 3 are connected by the coupling 6. The controller 7 and the battery 8 for controlling the rotation of the motor 5 are fixed to the vertical mounting portion 1c of the gantry 1.
The connection lines 9 electrically connect the two.

FIG. 1 (b) is an enlarged perspective view showing a portion B of FIG. 1 (a), that is, a connecting portion between the rotating shaft 3 and the monitoring container 4, and an upper end portion of the monitoring container 4 is
It has a rotary shaft insertion portion 4a and a pin insertion hole 4b formed in the rotary shaft insertion portion 4a. The lower end of the rotary shaft 3 is thick enough to be inserted into the rotary shaft insertion portion 4a, and has a pin insertion hole 3a. In order to connect the monitoring container 4 having such a configuration and the rotating shaft 3, the lower end of the rotating shaft 3 is inserted into the rotating shaft inserting portion 4a, and the positions of the pin inserting hole 3a and the pin inserting hole 4b are aligned,
Insert the pin 10 into them.

FIG. 2 is a view for explaining the construction and assembling sequence of the monitoring container 4, which is constructed as follows. With the same configuration as the above-mentioned glass element, a bottomed cylindrical glass element storage container 41 made of, for example, polyvinyl, and stored in the glass element storage container 41,
For example, a triangular prism-shaped storage body 43 made of expanded polystyrene,
Also, a monitoring container body 45 consisting of glass elements 42a, 42b, 4c arranged on the outer peripheral surface of the container 43, and a lid 44 for closing the opening of the glass element container 41, and the monitoring container body 45 are provided. It is composed of a lower container 46 and an upper container 47 to be stored. The glass elements 42a to 42c are placed in a glass element storage container 41, and these are fixed by using a triangular prism-shaped storage body 43.

The monitoring container 4 having such a structure is
An energy compensating filter (not shown) is provided between the monitoring container body 45 and the lower container 46 and the upper container 47, whereby the absorbed air dose can be directly measured.

In FIG. 1, when electric power is supplied from the battery 8 to the motor 5 and the controller 7, the motor 5 rotates at a predetermined rotation speed, and the monitoring container 4 also rotates accordingly. The rotation speed in this case can be arbitrarily adjusted by the controller 7.

By rotating the monitoring container 4 in this manner, it is possible to reduce the occurrence of an error due to the radiation incident direction from the environment at the measurement point when performing environmental monitoring, and to keep a small amount of leakage radiation at a natural level. Can be measured, and the dispersion among the plurality of glass elements 42a to 42c can be reduced.

This is also clear from the following experimental results. FIG. 3 is a diagram for explaining the experimental state, FIG. 3A shows the state seen from the upper part of the glass element storage container 41 when the motor 5 is not rotationally driven, and FIG.
Shows the state seen from the upper part of the glass element storage container 41 when the motor 5 is rotationally driven, and in each figure, Samples 1 to 6 show the positions of dosimeter samples. The result of having carried out the monitoring test for one month in each state is shown in FIG. In FIG. 4, C.I. V. Is a coefficient of variation, and the larger this value is, the larger the variation between samples is.

From the above experimental results, it can be seen that the following effects are obtained.

(1) When the monitoring container 4 is rotated, a substantially constant value can be obtained irrespective of the installation positions of the dosimeter samples 4 to 6. Therefore, there is a difference due to the natural level radiation direction characteristics of the dosimeter. It can be seen that is alleviated. On the other hand, in FIG. 2, the radiation from the right and left 90 degrees from the front of the glass elements 42a to 42c has a slightly lower sensitivity, so if the monitoring container 4 is installed in a fixed state, the radiation from the specific direction is obtained. Cannot be measured accurately.

(2) When a plurality of dosimeter samples 4 to 6 are installed at one monitoring point, variations between glass elements are reduced and reliable data can be obtained.

The present invention is not limited to the above-mentioned embodiment, but can be modified and implemented as follows. When the exposure direction is also observed by environmental radiation monitoring using the above-mentioned embodiment, the directions of several dosimeters (the same as those described above) are changed together with the dosimeter that automatically rotates to the observation point. It should be fixed and installed. By doing so, it is possible to measure the accurate radiation dose at each observation point from each automatically rotating dosimeter and the direction of exposure from each fixedly installed dosimeter.

[0021]

According to the present invention, when environmental monitoring is performed, it is possible to reduce the occurrence of an error due to the radiation incident direction from the environment at the measurement point, and to measure a very small amount of leakage radiation at a natural level. Further, when a plurality of dosimeter samples are installed, it is possible to provide a fluorescent glass dosimeter capable of measuring with a small variation among the dosimeter samples.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the configuration of an embodiment of a fluorescent glass dosimeter according to the present invention.

FIG. 2 is a diagram for explaining the configuration of the monitoring container 4 of FIG.

FIG. 3 is a view for explaining the function and effect of the same embodiment.

FIG. 4 is a view for explaining the function and effect of the same embodiment.

[Explanation of symbols]

1 ... Stand, 2 ... Bearing, 3 ... Rotating shaft, 4 ... Monitoring container, 5 ... Motor, 6 ... Coupling, 7 ... Controller, 8 ... Battery.

Claims (1)

[Scope of utility model registration request] 1. A monitoring container for accommodating at least one glass element that emits fluorescence when excited by ultraviolet rays after being activated by exposure to radiation on a gantry installed at a position where a radiation dose is to be measured, or said glass element. A fluorescent glass dosimeter, which is rotatably supported.