TitleThe 200-Curie Cobalt-60 Gamma -Ray Irradiation Facility forTextile and Polymer Studies (Special Issue on Physical,Chemical and Biological Effects of Gamma Radiation, XI)

Author(s) Ikeda, Tetsuo

Citation Bulletin of the Institute for Chemical Research, KyotoUniversity (1970), 48(1): 45-52

Issue Date 1970-03-31

URL http://hdl.handle.net/2433/76324

Right

Type Departmental Bulletin Paper

Textversion publisher

Kyoto University

Bull. Inst. Chem. Res., Kyoto Univ., Vol. 48, No. 1, 1970

The 200-Curie Cobalt-60 Gamma-Ray Irradiation

Facility for Textile and Polymer Studies

Tetsuo IKEDA

Received Jaanuary 14, 1970

A 200-Curie cobalt-60 gamma-ray irradiation facility for textile and polymer studies was installed at the Institute for Chemical Research, Kyoto University in 1969. This facility is

composed of a source container and gamma-ray irradiation system. As this facility is equi- valent to so-called "gamma cell", can be used even in experimental room without any

special buildings or constructions for prevention of leakages. The leakage of gamma rays of this facility is controlled by lead shieldings below 0.5 mr/h at the surface of the facility.

I. INTRODUCTION

Recently, studies using high energy irradiation are spreading in the field of high polymer chemistry and valuable results are now being obtained in both

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T. IKEDA

fundamental and technical studies.The studies of high polymer chemistry using

high energy irradiation may be broadly divided into two classes, namely irradia-

tion polymerization and polymer irradiation.

Chemical improvements of textile properties of various natural and synthetic

fibers by means of graft copolymerization of vinyl monomers, and dynamic

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( 46 )

The 200-Curie Cobalt-60 Gamma-Ray Irradiation Facility

properties or molecular structures such as crystallinity and orientation of some crystalline polymers, for examples polyethylene and polypropylene, are studied in this laboratory using high energy irradiation.

For these purposes, cobalt-60 200-Curie gamma-ray irradiation facility which is relatively simple structure and easy to handle is introduced in this laboratory. Outline of this facility is described briefly in this paper.

II. OUTLINE OF THE FACILITYy

II-1 Cobalt-60 source

Cobalt-60 source manufactured by General Electric Co., U. S. A., is a lmmcb x 1 mm pellet type with specific radioactivity of 20.4 Ci/g. Weight of a pellet is about 7 mg. The cobalt-60 pellets of total 9.8 g . are sealed in a stainless steel capsule shown in Fig. 1.

II-2 Structure This facility may be divided into three parts.

1. Cobalt-60 source container, 2. Source-driving device,

3. Irradiation box. Figure 2 shows the vertical figure of the facility, and Figs. 3 and 4 are the

photographs of the facility. The source container is right side (the position of exposure—normal state) in Fig. 3 and left side (the position of sampling) in Fig. 4, respectively.

II-2. a. Source container

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T. IKEDA

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The 200-Curie Cobalt-60 Gamma-Ray Irradiation Facility

This container is approximately cylinder type (Fig. 5) and designed to be

used not only as a container for cobalt-60 200-Curie source but also as a trans-

portation container of the source. Inside of the container is made of stainless steel and outside is of normal

iron steel, respectively, and between them lead for leak shielding is packed so

as to control surface leakage below 0.5 mr/h. The source capsule is connected

with a source-driving rod (Fig. 6) . The upper and under sides of the source are

packed with lead rods (about 280 mm length) for prevention of leakage toward upper and under directions. The rod containing the source is stored vertically

in the center portion of the container, and at the time of exposure, the source

capsule together with shielding lead rods are drived down to the bottom of ir-

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radiation chamber by the source-driving device (Fig. 7) .

The container is installed on a truck above the irradiation chamber and

source driving is possible only when the truck (the container) is at right position

above the irradiation box. Putting in and out of samples to be irradiated are

carried out after the truck (the container) is moved manually to left side (com-

pare Fig. 3 with Fig. 4) . II-2. b. Source-driving device

The exposure and housing of the source are made using an gear-driving

mechanism (Figs. 7 and 8), while manual operation can also be conducted through

the handle installed on the control panel. The position of the source is indicated

both by mechanical indicator and pilot lamps installed on the control panel. It requires about 10 sec to exposure the source from the container to the bottom of

the irradiation chamber in the case of electric drive.

II-2. c. Irradiation chamber Size of inner part of the irradiation chamber is about 30 mmm x 320 mm. A

stainless disc with aluminum sample holders is placed at the bottom of the irra-

diation chamber. The sample holders are arranged in five concentric circles ar-

round the source, as shown in Fig. 10. Temperature in the irradiation chamber

is controlled from room temperature to about 100°C by a thermister thermometer

and heaters surrounding the chamber. Lead shieldings surrounding the outer

side of the chamber are used for prevention of leakage at the time of exposure. 1I-2. d. Electric circuit

Figure 9 shows electric circuit for the source driving.

I1-3. Dose rate and leakage

Dose rates at some points were measured with the fluoroglass dosimeter (To-

shiba FD-R1 fluoroglass). Measuring points and results are shown in Fig. 10 and

Table 1, respectively.

Leakages of gamma-rays at the time of exposure were measured using a transistorized GM radiation survey meter (Fujitsu Limited, SM-102). No leakage

over 0.5 mr/h was observed at any points of the surface of the facility.

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The 200-Curie Cobalt-60 Gamma-Ray Irradiation Facility

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T. IKEDA

Table 1. Dose rates measured with fluoroglass dosimeter.

Measuring pointsDose rate x 104 (r/h) Li

neNo.Height (mm)

108.26

1607.74 1706 .29 6707.90

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l1302.56 1702.63 13702.89 101.55

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ACKNOWLEDGENTS

The auther would like to express his sincere gratitude to Professor S. Shimizu

and Mr. R. Katano for their kind supports and suggestions. He is also indebted

to the Kimura Kakoki Co. Ltd. and Mr. T. Utsunomiya for the construction of

this facility.

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