JPS63221278A - Irradiation dose detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ionizing radiation radiation dose-sensitive detector, and in particular,
The present invention relates to an irradiation dose detector suitable for use as a sensor for controlling irradiation dose of a radiation irradiated object.

[Conventional technology]

Conventionally, when irradiating with a gamma ray irradiation device, the dose rate of the irradiation field was measured in advance, and then the dose rate required for the reaction was estimated based on the time.

In this case, the dosimeter used for measurement is described in, for example, radiation chemistry-related literature (Radiation Chemistry (70Nasha,
Chemical dosimeters such as P76-93) (1980) are common. The most popular measurement method is the Fritzke dosimeter, in which divalent iron ions (Fe"+) are oxidized by hydrogen peroxide (H2, □ Z ) produced by radiolysis of water in an aqueous solution. becomes iron ion (Fe3+).At this time, the ratio of Fez+→Fe3+ is proportional to the absorbed dose, so the dose rate can be found by expressing the absorbed dose as the quotient of the irradiation time.

In addition, glass dosimeters are known as solid-state dosimeters.

The dose range that can be measured with these dosimeters is 10” to 10
'G: y range.

On the other hand, the dose required for irradiation varies depending on the substance and application, but for polymerization reactions of polymeric materials, the dose required for irradiation is 103 to 3-0'.
108 for sterilization and sterilization of Gy, food, medical equipment, etc.
~10'Gy is required.

If you accurately measure the dose rate of the irradiation field with this dosimeter,
The required irradiation dose can be obtained by controlling the irradiation time.

[Problem that the invention seeks to solve]

However, in the conventional irradiation method described above, the strength of the radiation source remains unchanged,
It is also assumed that the object to be irradiated is point-like and that internal absorption can be ignored. Whenever the intensity of the radiation source changes, it is necessary to measure the dose rate of the irradiation field using this method. This chemical dosimetry method is a highly reliable measurement method, but since it deals with solutions, it requires basic chemical analysis techniques, and it cannot be said to be an easy and versatile method for general users. Also,
The sample solution also requires a certain amount or more, and there is a risk of scattering, so it cannot be said that it is easy to handle, and it is inconvenient when trying to irradiate the object at the same time. Furthermore, the biggest problem is that it is difficult to know the cumulative dose while irradiating the measurement results.

The purpose of the present invention is to extract measurement information related to irradiation dose as an electrical signal on the spot, and based on this signal, quickly perform operations such as transferring the irradiated object and storing the source after irradiation is completed, thereby improving the accuracy of irradiation control. The objective is to provide a simple sensor material that enables high automation.

In order to achieve the above objective, we focused on manufacturing conductive polymer materials by radiation polymerization reaction, irradiating a certain amount of radiation, obtaining a conductive signal when the polymerization reaction is completed, and performing operations after the irradiation is completed or after completion. Perform display.

The conductive polymer material is a polymer of acetylene (CHCH), polyacetylene (P, A), or diacetylene (R-C
C-CC-R') polymer polydiacetylene (PDA)
It has been known. (Region of Chemistry, Vol. 35, No. 3 (1980)
(2013) Description) Of these, PDA polymerizes in the same phase, so it can be polymerized by heat, light, or radiation just by applying a solid powder. PDA that is polymerized by γ-rays is pTs (substituent: paratorconesulfonate・-CHy
, -0-802-CaHa-CHa) and 3BCMU (substituent: butoxy carbonyl methylurethane:
(CHz)s-OCO-NH-CHz-COO(CHz
)a-CHa) is known. The conductivity of these solid phase polymerized polymer crystals varies depending on the manufacturing conditions, but when used alone they are insulators (10-'S/cm or less), but after polymerization they range from 10-'S/a!1 to 15Z1. Therefore, when monomolecular powder of diacetylene is placed in a layer between the electrodes and γ-rays of 104 Gy to 10 δay are irradiated, the polymerization reaction proceeds and the rise curve can be seen by measuring the conductivity. can be measured, i.e.
If the relationship between the irradiation dose and the polymerization reaction rate is determined in advance, it is possible to detect when a certain irradiation dose has been reached and convert it into an electrical signal. If this is made into a sensor, there are advantages such as being able to measure multiple points to obtain the a mass rate distribution, and applying the signal to control the irradiation device.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3. FIG. 1 shows a state in which a monomolecular diacetylene powder 1 is sandwiched between a pair of electrodes 2, and both ends are supported by an insulating material 3. In addition, from the gamma ray source 5 such as cobalt (6°Co), for example, in the case of PTS, 6X10' at room temperature.
When irradiated with a radiation dose of Gy, the powder of diacetylene alone undergoes a polymerization reaction and becomes a polymer crystal 6. The state is shown in FIG. Therefore, if monitoring is continued with the ammeter 4 during this irradiation, the completion point of the reaction, that is, the irradiation dose can be determined.

Since the polymerization reaction proceeds not only with gamma rays but also with ultraviolet rays and heat, quality control before irradiation must be planned. However, if this property is used to advance the polymerization reaction by applying heat or light irradiation in advance, the polymerization reaction can be completed with a small amount of γ-ray irradiation. By using diacetylene powder whose sensitivity has been adjusted through these pretreatments, it is possible to obtain any dose and the corresponding electrical signal.

Next, an example in which the irradiation dose detector shown in FIG. 2 is applied to an apparatus will be described with reference to FIG. 3. Figure 3 shows an example in which polymeric materials that undergo polymerization and crosslinking reactions, medical instruments and foods for sterilization and sterilization are placed in boxes or baskets, and irradiated sequentially in a batch manner. The object to be irradiated is placed in a box, and the irradiation dose detector 11 has the above-mentioned diacetylene powder sandwiched between electrodes inside the box.
Insert. The pre-irradiation object 12 is moved to the central irradiation field by a crane 16. An irradiated object 13 is placed at a predetermined location and exposed to gamma rays generated from a radiation source 15 made of, for example, 80Co. In this example, the solid state polymerization of the diacetylene powder is completed upon receiving an irradiation dose of 6 X 10'G y. When conductivity is interrupted, a current of a certain level or higher flows between the two electrodes, so this is detected by the detection circuit 17, signal processing is performed by the control and display unit 19, and the crane driving device 18 is operated. As a result, the irradiated object 13 is transferred by the crane to the outside of the biological shielding wall 20 as an irradiated object 14. Although this embodiment uses a batch method in which the materials are transferred by a crane, the transfer means may also be a belt conveyor. Further, operations after irradiation include not only moving the irradiation object but also automatically storing the radiation source in the storage hole.

When transferring the irradiated object in a continuous manner, use a crane,
Alternatively, in order to control the speed of the belt conveyor, optimization calculations are performed while measuring the time required to obtain a predetermined dose.

Note that it is also possible to measure the dose distribution and dose rate by adjusting the dose required for polymerization by changing the polydiacetylene material (type of N substituent), heat treatment, or pretreatment with ultraviolet light or ultraviolet irradiation. be.

〔Effect of the invention〕

According to the present invention, the irradiation dose detector can be miniaturized to the extent that it fits in one corner of the box of the irradiated object, and by embedding it in the irradiated object, it can be used inside the irradiated object with the same shape but different contents. The actual irradiation dose can be electrically detected without being affected by the absorption of radiation, and information related to the dose can be obtained at the same time as the irradiation, making it easier to automate the irradiation equipment.

[Brief explanation of the drawing]

Claims (1)

[Claims] 1. Consists of a structure in which a monomolecular compound that solid-phase polymerizes when irradiated with ionizing radiation is attached or packed in a layer between a pair of electrodes, and polymerizes when exposed to a predetermined amount of irradiation to form a conductive polymer crystal. An irradiation dose detector characterized in that when the irradiation dose is detected, the irradiation dose is detected by obtaining conductivity between the electrodes that exceeds a specified value.