JPH0697262B2 - Fine-grained amino acid radiation dosimeter element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention accurately and simply measures absorbed doses of ionizing radiation such as γ-rays, X-rays, electron beams, heavy charged particle beams and neutron beams. The present invention relates to a fine-grained amino acid radiation dosimeter element for performing.

[Prior Art] In recent years, large-scale facilities handling radioactive materials such as nuclear power plants and radiation waste treatment facilities, and various irradiation facilities such as particle beams and γ-rays have become widespread. In these facilities, it is required to accurately and simply evaluate the radiation dose over a wide dose range not only in the normal environment but also in the environment such as high temperature and high humidity.

Conventional solid-state radiation dosimeters for the purpose of high-level dosimetry from 10 Gy to 100 kGy include thermoluminescence dosimeters, lyoluminescence dosimeters, polymethylmethacrylate dosimeters, diachromic die film dosimeters, and cobalt glass. Dosimeters are known. After irradiating the solid-state element with radiation, all of these measure the amount of light emitted from the solid-state element or the absorption of light of a specific wavelength to obtain the irradiation dose. There are problems such as large changes and narrow effective dose measurement range.

Amino acids generate stable radicals (free radicals) that are stable in proportion to the dose of radiation when they are irradiated in the crystalline state. Therefore, the concentration of produced radicals per unit weight can be determined by an electron spin resonance (ESR) device. It is possible to measure According to this method, a wide range of doses from 10 Gy to 100 kGy can be measured, and since the change (decay) in the number of radicals is extremely small at about 2% in two years, the change over time in the dose response is comparable to the above dosimeters. There are few differences.

[Problems to be Solved by the Invention] Dosimetry using an amino acid is based on the number of radicals in the crystal as described above, and a constant amount of the amino acid crystal powder is always the measurement target, that is, the binder. It is important to make a device in which the amino acid crystal powder is uniformly dispersed therein and has a constant size. However, in the conventional radiation dosimeter element, an amino acid crystal powder having a relatively large particle size has been used, the variation in the element size is large due to poor moldability, and it is difficult to uniformly disperse in the binder, It is a cause of measurement error. Further, the mechanical strength is insufficient and there is a problem in handling.

The present invention has been made based on the above, by making the dispersion of the amino acid crystal powder in the binder uniform and the element size uniform, it is possible to eliminate the measurement error, also excellent mechanical strength. An object of the present invention is to provide a radiation dosimeter element having the above.

[Means for Solving Problems] The fine-grain amino acid radiation dosimeter element of the present invention is characterized in that amino acid crystal powder having a particle size of 500 μm or less is molded into a predetermined shape with a binder.

As the amino acid crystal powder, glycine which is a monoaminomonocarboxylic acid, valine, leucine, serine which is an oxyamino acid, cysteine which is an amino acid containing sulfur,
Cystine, monoaminodicarboxylic acid lysine, arginine, aromatic ring amino acid phenylalanine, anthranilic acid and the like having relatively low molecular weight and high crystallinity are effective.

It is necessary to use such an amino acid crystal powder having a particle size of 500 μm or less. If the particle size is larger than this, it is difficult to make the dispersion in the binder uniform and the device dimensions uniform due to deterioration in moldability. Also, the mechanical strength of the device is reduced. The particles of the amino acid crystal powder have an elongated needle shape or a rectangular shape, and the crystal length is the particle size in the present invention. Examples of the method for controlling the particle size of the amino acid crystal powder include a method of classifying a commercially available amino acid crystal powder by sieving and a method of mechanically crushing and classifying with a fine pulverizer. Examples of the binder include natural rubber, synthetic rubber, and synthetic resin, and in particular, those having a small amount of radicals generated by radiation or those having a rapid decay of generated radicals are preferable.

As the synthetic rubber, ethylene propylene (-diene) copolymer, ethylene-vinyl acetate copolymer, chloroprene rubber, nitrile rubber, butyl rubber, synthetic isoprene rubber, styrene butadiene copolymer, styrene-butadiene-acrylonitrile copolymer, Examples thereof include butadiene rubber, acrylic rubber, urethane rubber, silicone rubber, chlorosulfonated polyethylene, polyisobutylene, polyester rubber, epichlorohydrin rubber, and tetrafluoroethylene-propylene alternating copolymer.

Examples of the synthetic resin include paraffin, polystyrene, acrylonitrile-styrene resin, hard acrylonitrile-butadiene-styrene resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polycarbonate resin, polyethylene, polypropylene, polyester resin, nylon 12 and the like.

The mixing ratio of the binder and the amino acid crystal powder is not particularly specified, but the upper limit depends on the molding processability and whether or not the mechanical properties practical when handling the molded body are maintained, and the lower limit is as a dosimeter element. Determined by whether or not it contains an effective amount of alanine, amino acid crystal powder 10 to 1000 parts by weight, preferably 100 to 600 parts by weight with respect to 100 parts by weight of the binder.
It is appropriate to select from the range of parts by weight.

In the present invention, an antioxidant and a lubricant may be appropriately contained in addition to the above components. By adding an antioxidant and a lubricant, it is possible to suppress an increase in predose during kneading and molding, and improve the measurement accuracy.

[Examples of the invention] Examples 1 to 10 As shown in Table 1, a predetermined amount of alanine crystal powder having different particle sizes was used for low density polyethylene (UB, manufactured by Ube Industries, Ltd.).
EC-400) and then extruded into a 3 mmφ rod by an extruder.

Examples 11 to 12 Using glycine crystal powders having different particle sizes, Example 1
Extruded into a rod shape in the same manner as ~ 10.

Comparative Examples 1 to 3 Alanine crystal powder having a particle size larger than the specified value of the present invention was used, and extrusion molding was performed in a rod shape in the same manner as in Examples 1 to 10.

Table 1 shows the results obtained by measuring the dimensional uniformity, appearance, variation in measured values, and tensile properties of the dosimeter elements manufactured in the above Examples and Comparative Examples. Regarding the variation in the measured value, the variation in the peak height of the ESR spectrum of 20 elements irradiated with 2 × 10 ⁴ R measured by an electron spin resonance (ESR) device is shown in%.

[Effects of the Invention] As described above, by using the amino acid crystal powder having a particle size of 500 μm or less, the appearance, the uniformity of the size and the extrusion moldability are improved, and the measurement variation can be reduced, and the excellent mechanical property is obtained. It becomes possible to obtain a fine-grained amino acid radiation dosimeter element.

Claims (1)

[Claims] 1. A fine amino acid radiation dosimeter element, characterized in that an amino acid crystal powder having a particle size of 500 μm or less is molded into a predetermined shape with a binder.