An introduction to gamma irradiation center

Radiat. Phys. Chem. Vol. 35, Nos 4--6, pp. 560--564, 1990 Int. J. Radiat. Appl. lnstrum., Part C Printed in Great Britain

0146-5724/90 $3.00 + 0.00 Pergamon Press plc

AN INTRODUCTION TO GAMMAIRRADIATION CENTER

M. SOHRABPOUR Gamma Irradiation Center, Atomic Energy Organization of Iran, P.O. Box 11365-8486, Tehran-lran

ABSTRACT Radiation processing status in the Islamic Republic of Iran is reviewed. GammaIrradiation Center is the only center offering irradiation services to the manufacturers of disposable medical and hygienic supplies in the country. As a promoter of this technology GIC has also assumed a role and developed capacities for quality control, research and development in this expanding field of endeavor. The personnel, physical f a c i l i t i e s , operations record, quality control, and research activities of the GIC is presented. KEYWORDS Gamma Irradiation Center, GIC, radiation processing, process control, research, IR-136, I.R. of Iran. INTRODUCTION Gamma Irradiation Center, was the f i r s t center of its kind that introduced radiation processing on a p i l o t scale in the Islamic Republic of Iran. Previously there had been applications of gammarays for research purposes in the areas of sprout inhibition of root crops (Sekhavat et a l . , 1978) and wood-plastic composites (Gouloubandi, 1980) in I.R. of Iran. In the changing scientific climate of post-revolutionary Iran the notions of establishing this center was conceived and a cooperative project in the frame work of the UNDPdevelopmental cooperations was considered as an appropriate mechanism of implementation. Consequently a t r i p a r t i t e project involving Atomic Energy Organization of Iran, AEOI, United Nations Development program, and the International Atomic Energy Agency, IAEA, was defined, formulated, and project document was signed on September of 1982. The site selection, ground preparation, construction of the irradiation cell, as well as, the laboratories, offices etc. took about two years to complete. However, due to the prevailing state of war at that time the installation of the irradiator was delayed for several months and as a result the commissioning and inauguration of the center took place on October of 1985. DEVELOPMENT OBJECTIVES This project was to achieve the following principal objectives: i ) Establish a pilot scale irradiator for radiation processing of disposable medical supplies, i i ) Conduct research and development programs on the quality control of disposable medical supplies, and i i i ) Train Iranian nationals in the field of radiation technology. As w i l l be demonstrated in the following sections these objectives have been f u f i l l e d successfully. In addition during the course of execution of this project or shortly thereafter two additional laboratories i.e. food irradiation and environmental measurement laboratories were constructed and as a result new dimensions have been added to the functions of the GIC.

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LOCATION AND DESIGN GIC is located to the north western part of Tehran and is built adjacent to the premises of the AEOI. A large number of manufacturers of medical and hygienic supplies are found within a 50 km radius of the GIC. However, many factories located at relatively larger distances from Tehran, up to 1000 km, also bring and process their products at the GIC. GIC is set up in an area of 10000 m2 of land space. The building complex has about 3400 m2 of floor space. The center is divided into two functionally separate areas of production wing, and the laboratory and administration wing. Production section contains irradiation c e l l , control room, machine shop, about 200 m2and 600 m2 of storage areas for untreated and treated products respectively. This section is also served with a large parking, loading, and unloading docks. The laboratory and the administration section is located to the south of the production section and contains six laboratories, plus offices, and a conference hall. This wing is also served with a separate entrance and parking f a c i l i t y . Sufficient land space is set aside around the center for any future building expansions. Figure 1 shows the floor plan of the GIC.

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Floor plan of the

Gamma Irradiation Center .

FUNCTIONS AND PERSONNEL Because of the pioneering role of the GIC in the area of radiation processing in the country as well as its varied laboratories and fine equipment i t already has assumed a position of prominance in the country in the applications of radiation processing. In this connection i t offers irradiation services, performs research and quality control on pre- and post-irradiated products. GIC actively promotes cooperation with the universities by offering fellowships to graduate students to work in special research topics of interest having relevance to the cause of radiation processing or other areas in the work domain of the GIC laboratories or i t s scientif i c staff members. These research projects usually lead to obtaining of advanced academic degrees. Figure 2 shows the scope of functions of GIC, i t s collaborations with the academic and regulatory institutions as well as services that are offered to the industries. Current number of GIC personnel is 42 persons. This number is distributed into the following job categories: scientific 12, technical and administrative 8, technicians and operators 15, and manual workers 7 persons,respectively. The irradiator operations group is composed of three separate subgroups who work on 24-hour shifts, and each take two shifts per week.

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FUNCT I ONS

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Fig. 2.

Services

GIC Functions and coordination with local educational, regulatory, and industrial concerns.

LABORATORIES AND EQUIPMENT Various quality control and quality assurance activities are performed in support of the ongoing radiation processing at the GIC. In addition research projects in related areas are also performed to promote new applications of radiation processing in the country. Someof these activities include bioburden and s t e r i l i t y analysis, food analysis, trace element measurement, high dose dosimetry, polymer testing etc. These activities are performed in six different laboratories. Table 1. gives a l i s t i n g of these laboratories together with some of their major available instruments. Table 1.

Laboratories and major equipment items at Gamma Irradiation Center.

Laboratory

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Available

Instruments

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Dosimetry

I~--VIS ~pootrophotometer. Oyen. Gemma c e l l

(18 kCf Co-60).

TLD System; Dosimeters used: Rod p e r s p e z , ECH, F r i o k e , Food Irrad.

~oolave,

Environmental

AAS. Gamma Speotroseopy system.

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IRRADIATOR SYSTEMAND PROCESSING RECORD Gamma irradiator, IR-136, used in GIC is of AECL (Nordion) design. I t is a carrier plant having 69 carriers each with four irradiation shelves, dimensions 45x45x45 cm. Carriers make three passes on each side of the source rack or six passes in total. I t is a plant with product overlap and i t has an efficieny and overdose ratio of about 30 and 20 percent respectively at a product bulk density of 0.15 gm/cm3. More information on performance and dose mapping of this plant is given in another article in this proceedings (Raisali et a l . , 1989). Also more detailed technical specifications are given in the plant reference manual (AECL, 1985). Present source a c t i v i t y of the irradiator after a mid-course re-loading is about 7.8x1015 Bq (210 kCi). Our yearly number of processed cartons has shown a very impressive record. During the third year of operation about 116000 cartons or 10600 m3 of products have been processed at GIC which show more than ten and four fold increases relative to the production levels of f i r s t and second year of operations respectively. Figure 3 shows the histogram of the number of cartons processed on.a yearly basis during the three years of operation of our irradiato~

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No . of processed cartons during last three years of GIC's operation . Each carton volume = 0.091 m3.

PROCESS CONTROL Any new product considered for radiation processing at the GIC usually goes through three stages of control. These controls are applied at the time of receipt of application form, on sample analysis stage, and at the stage of processing of the actual production batches. Application Stage During this stage various licences, permits and production records of the prospective customer are inspected. Manufacturing f a c i l i t y is v i s i t e d , adherence to GMP is reviewed. Sample Testin 9 Stage In this stage the raw material as well as the manufactured product from the view point of microbiological quality and response to radiation treatment is assessed packaging materials are also tested. A complete status report on the bioburden, material testing results, as well as, the required dose value is prepared and submitted to the customer. A few irradiated samples are also given to the customer for his own or that of the regulatory agencies control. Batch Processing Stage With each consignment of product an application form requesting irradiation services at a specific dose is received. This information is usually obtained by the customer from the report that was provided to him at stage two. Random sampling and bioburden testing is again performed. S t e r i l i t y assurance level, SAL, is proposed, dwell time for machine operations is set, radiation dosimetry is performed. Upon completion of irradiation, and final control of the entire process, dosimetry c e r t i f i c a t e is issued and product is released. As to the matter of legal responsibility, GIC only c e r t i f i e s the absorbed dose value that is given to a product and the responsibility for s t e r i l i t y rests with the manufacturer only.

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RESEARCH ACTIVITIES The multi-disciplinary nature of GIC together with i t s many and varied laboratories and modern equipment has created an excellent setting for i n i t i a t i o n and conduct of research. At present time we have several graduate students who are pursuing thesis projects for completion of their M.S. and Ph.D. degrees in various fields of polymer technology, radiation physics, pollution assessment, microbiology, and food irradiation etc. The existing projects in addition to irradiation services are expected to enhance the level of awareness of the various government o f f i c i a l s and decision makers regarding the potential benefits of radiation processing for the well being of the society, and thereby, i t should increase their support for further programs of research and development in radiation processing. Table 2 shows some of the on-going research projects at the GIC. Table. 2.

Someof the current research projects at the GIC. RESEARCH PROJECTS

- Assessment of the dominant types of microorganisms found on the locally manufactured disposable medical supplies. - Determination of the DIO values of different types of microorganisms found on locally produced medical supplies. Effect of radiation on pbyslcal and chemical properties of polypropylene. - Radiation stabilization of polypropylene. - Determination of the dose to marrow, eyes, thyroid and skin of the Iranian population arising from diagnostic radiology. - Identi flcation of irradiated foodstuffs by thermeIumlnescencetechnique. - Dose response of agrlcuItural products l l k e potatoes, onions, garIics, strawberries, dates, figs, pistachio nuts etc. - Feeding studies of the irradiated food involving laboratory animals. - Determination of the major trace elements found In the atmosphere of Tehran using the methods of INAA and AAS. - Development of an analytical model for the dose rate mapping of gamma Irradlator systems. - Ten~oerature response of a number of hlgh dose dosemetara. - Applicatlons of the SIT method to confoat certain varlety o f local insects. i'

CONCLUSIONS Based on the foregoing discussions, i t is shown that radiation processing technology has been introduced in the Islamic Republic of Iran by establishment of the GammaIrradiation Center. GIC is shown to be a well integrated center thatcombines various complementary functions of service irradiation, quality control, and research. These different tasks of the GIC are coordinated with the needs of the relevant industrial firms, the existing local or international regulatory guides, and has also provided new possibilities or directions for cooperations with the universities in the areas of applied academic research. During i t s three years of operation GIC has demonstrated that there is a great potential for use and further expansion of radiation processing in the I.R. of Iran ACKNOWLEDGEMENT The author wishes to express his appreciation to Mr. F. Ghods Mirhydari for computer graphics design and to Mrs. S. Marandi for typing of the manuscript. REFERENCES AECL, (198S). Co-60Irradiator Operator's Manual, Model IR-136 for IAEA-IRAN, Ed. 1. Gouloubandi R., (1980). Wood-Plastlc Composites using woods native to Iran. Proc. IMRP2. Miami FL. U.S.A. Raisali, G.R., M. Sohrabpour, and A. Hadjinia (1989). A Computer code for dose rate mapping of gamma irradiators. IMRP7, Noordwijkerout, NL. Sekhavat, A., Z. Zare, M.G. Kudva, K.L. Chopra, and J.M. Sharitpanahi (1978). Preservation of Potatoes and Onions by Irradiation and Chemical Treatment. Food Preser. Irrad. IAEA Symp. Wagen. NL, Vol.1, pp. 83-97.