JP3064538B2 - Fluorescent glass dosimeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates, on the optimal fluorescent glass dosimeter to measure the radiation dose radiation exposure, such as nuclear power plants.

[0002]

2. Description of the Related Art Generally, a glass element for a fluorescent dosimeter made of a phosphate glass containing silver ions is used as a fluorescent glass dosimeter. This glass element is exposed to radiation
After being activated by exposure , it emits fluorescence when excited by ultraviolet light having a wavelength of 300 to 400 nm. In this case, the fluorescence intensity is proportional to the radiation exposure dose, by detecting the fluorescence intensity, it is possible to measure the radiation exposure dose.

[0003] In measuring such radiation dose,
The light emitted from the ultraviolet excitation light source is passed through an optical filter to selectively extract ultraviolet light of a predetermined wavelength, and then enters one surface of a rectangular parallelepiped fluorescent glass element for a fluorescent dosimeter. Here, the fluorescent glass element that has received the ultraviolet light of a predetermined wavelength emits fluorescence, but the fluorescence emitted at this time passes light of a predetermined wavelength range through an optical filter,
Give the electrical signal of a level substantially proportional to the photoelectric conversion to the fluorescence intensity by the photomultiplier, the fluorescence intensity from the level of the electric signal, thus, is to measure the radiation radiation exposure dose.

[0004]

By the way, when each energy of γ-rays and x-rays is conventionally applied to a fluorescent glass element, in a certain energy region, an excessive response is exhibited, and so-called energy dependence is caused.

Therefore, in a general fluorescent glass dosimeter, as shown in FIG. 2, in order to compensate each energy of γ-ray and x-ray, the fluorescent glass dosimeter is connected to the fluorescent glass element 2 via an energy compensating filter 1 made of, for example, a metal filter. Irradiation is adopted. In addition, these are accommodated in the container which consists of the bottom body 3 and the lid body 4.

However, in the fluorescent glass dosimeter having the filter 1, when high energy γ-rays of 3 MeV or more are irradiated, secondary electrons are generated due to the interaction between the filter 1 and the high energy γ-rays. This causes the fluorescent glass element 2 to exhibit excessive responsiveness, resulting in energy dependence. That is, in the conventional fluorescent glass dosimeter, the amount of fluorescence detection increases for high energy γ-rays of 3 MeV or more due to the excessive response of the fluorescent glass element 2, and the radiation dose is measured accurately. It is difficult to do. For this reason, in a nuclear power plant or the like that may be exposed to high-energy γ-rays of 3 MeV or more, development of a fluorescent glass dosimeter capable of accurately measuring a radiation dose without excessive response is desired. Therefore, an object of the present invention is to provide a fluorescent glass dosimeter that can accurately measure high-energy γ-rays of 3 MeV or more.

[0007]

Means for Solving the Problems The present invention for achieving the above object, is activated by radiation radiation exposure, and a fluorescent glass element which emits fluorescence by being excited by ultraviolet light, at a position facing to the fluorescent glass element It is arranged, between at least one e conservation in Energy fluorescent glass dosimeter equipped with a compensation filter, the fluorescent glass element and the error Ne Energy compensation filter for d Ne Energy compensation desired γ-rays and x-rays is disposed to absorb secondary electrons produced when a gamma rays or high energy 3MeV is irradiated on the e conservation energy compensation filter, and is itself, gamma rays or high energy 3MeV is A substance that does not emit secondary electrons even when irradiated is provided.

[0008]

According to the present invention, between the fluorescent glass element and Effects conservation Energy compensation filter to absorb secondary electrons generated from the filter by γ rays or high energy 3 MeV, and per se Since a substance that does not emit secondary electrons is provided, high energy γ-rays of 3 MeV or more can be accurately measured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. This example, absorb in the conventional example of FIG. 2, between the fluorescent glass element 2 and d conservation Energy compensation filter 1, the secondary electrons generated from the filter by γ rays or high-energy 3 MeV, In addition, a substance (secondary electron absorbing material) 5 which does not itself emit secondary electrons, for example, one of plastic Pl and aluminum Al is provided.

With this configuration, 3 MeV
The above high-energy gamma rays can be measured with high accuracy. This is apparent from Table 1 showing the results of the experiment performed as follows.

Table 1 shows that several tens of samples constructed as shown in FIG. 1 were manufactured, and these were produced at a high energy γ of 3 MeV or more.
Line, for example, ¹⁶ N-γ ray (6.1 MeV), and a reference γ ray, for example, ¹³⁷ This is a comparison of the amount of fluorescence detected by the fluorescent glass element in both cases when irradiated with Cs-γ rays (0.66 MeV). Table 1, on the phantom simulating the actual measurement conditions, after the setting of the fluorescent glass dosimeters, ¹⁶ N over γ
Lines and ¹³⁷ This is a fluorescence detection amount ratio obtained by irradiating Cs-γ rays with the same dose equivalent and comparing the fluorescence detection amounts.

[0012]

[Table 1]

As apparent from Table 1, the sample N
O. In the case where only the metal filter is used (corresponding to the conventional example) as in 1 to 3, since the secondary electrons are generated by the interaction between the metal filter and the high-energy γ-ray, the fluorescence detection amount of the fluorescent glass element increases, and the measurement is performed. Accuracy decreases. This tendency is greater for metals with higher atomic numbers. However, the sample No. In the cases of Nos. 6 and 9, it is particularly excellent, and it can be seen that the fluorescence detection amount ratio falls within 1.00 ± 5%.

That is, the sample NO. No. 6 shows a case where a copper (Cu) filter having a thickness of 2.0 mm is used as a metal filter and a plastic Pl having a thickness of 1.0 mm is used as a secondary electron absorbing material. The ratio is 1.03. Sample No. Reference numeral 9 denotes a case in which a copper (Cu) filter having a thickness of 1.0 mm was used as a metal filter and a plastic Pl having a thickness of 2.0 mm was used as a secondary electron absorbing material. The ratio is 1.05. Therefore, 3 MeV or more high-energy γ-rays ⁽¹⁶ N) against a reference to γ-rays ⁽¹³⁷ Cs), there is no difference in the amount of detected fluorescence,
It can measure with high accuracy.

In the embodiment described above, any one of lead (Pb), tin (Sn), and copper (Cu) is used as the metal filter.
Alternatively, use a combination thereof, and use plastic Pl, aluminum (Al) as a secondary electron absorbing material.
Or a combination thereof, but the material, thickness, and arrangement method may be arbitrarily changed. In short, a γ-ray of high energy over 3 MeV, ¹³⁷ Anything may be used as long as there is no difference in the fluorescence detection amount of Cs-γ rays.

[0016]

According to the fluorescent glass dosimeters present invention, between the fluorescent glass element and Effects conservation Energy compensation filter, 3
By γ rays or high energy MeV absorb secondary electrons generated from the filter, and, since it itself has provided the material does not emit secondary electrons, upon measurement of radiation radiation exposure, more high 3MeV Energy gamma rays can be measured accurately.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of a fluorescent glass dosimeter according to the present invention.

FIG. 2 is a sectional view schematically showing an example of a conventional fluorescent glass dosimeter.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal filter, 2 ... Fluorescent glass element, 3 ... Bottom body, 4
... lid, 5 ... secondary electron absorbing material.

Claims (1)

(57) [Claims] 1. A is activated by radiation radiation exposure, and a fluorescent glass element which emits fluorescence by being excited by ultraviolet light, is disposed at the position facing to the fluorescent glass element, e conservation Energy compensation desired γ-rays and x-rays in the fluorescent glass dosimeter comprising at least one <br/> et conservation energy compensation filter, the disposed between the fluorescent glass element and the error Ne energy compensation filter, high energy above 3MeV absorb secondary electrons generated when the gamma rays were irradiated to the e conservation energy compensation filter, and, itself, gamma rays or high energy 3MeV does not emit secondary electrons be irradiated material , fluorescent glass dosimeter comprising comprising a.