Ionizing radiation can modify physical, chemical, and biological properties of materials, which has resulted in its wide use in industry, medicine, and science. The industrial uses of ionizing radiation include a broad range of applications that continue to increase both in kind and in number. The DIIF database focuses on industrial irradiation facilities, which are typically equipped either with high activity gamma sources or with electron accelerators.
Over the decades many gamma ray irradiators have been built and it is estimated that several hundred of them are currently in operation in Member States of the IAEA. They are relatively robust, simple to operate, and highly reliable. However, gamma sources are also portable and can be lost, stolen, or misused. Low energy electron beam technology (~100 keV - 1 MeV) has been in use for several decades for material modification applications. Since the late 1990s, due to the increased availability and reliability of of 1 - 10 MeV electron beam irradiators, sterilization processes based on accelerator technology have become more common. Nevertheless, the use of e-beam is limited as even though they provide high dose rates and high product throughput, the radiation penetration depth is low and the dose distribution in the product is non-uniform. On the other hand, X-ray irradiators, based on the same electron accelerators, combine the advantages of the electron beam (high dose rates and low security concerns) and the gamma sources (high penetration depth and good dose uniformity). One of the biggest hurdles for X-ray irradiators is their high cost, however, recent developments of high power and high energy accelerators provided a significant boost to use of X-rays for industrial applications.
Gamma irradiation is an established and simple technology with about 500 MCi of cobalt-60 installed at about 200 facilities. However, recent perturbations in cobalt supply, and sharp increases in its cost have made many users consider alternative technologies. E-beam technology has gained popularity, but it is not suitable for many products. In addition, it requires much more complex machinery and maintenance which can result in prolonged shutdowns. It also requires a reliable supply of electricity, which can be an issue in some countries. However, it is very cost efficient and provides very high product throughput. X-ray technology is similar to e-beam in requirements as it uses the same accelerators. However, during the electron-to-photon conversion a significant fraction of energy is lost and the economic viability is not as great as in the case of an e-beam. On the other hand, this method can be used for a much wider portfolio of products. Several facilities now equip their accelerators with removable x-ray converters so that they can be used in both modes, e-beam and x-ray, as needed. The three main irradiation modes described above, and their advantages and disadvantages are summarized below:
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Gamma |
E-beam |
X-ray |
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Technology | -
Relatively simple and reliable
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Good uptime
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Complex
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Fair uptime
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Requires more personnel
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Complex technology
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Fair uptime
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Requires more personnel
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Products | -
Good penetration, can treat “dense” products
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Poor penetration, limited to low density and thin materials
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Good penetration, can treat “dense” products
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Maintenance | -
Cobalt needs to be replaced regularly
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Limited suppliers and uncertainty of future availability of cobalt
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High price of cobalt
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Requires stable power supply and backup systems for critical utilities
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Maintenance service contract usually required
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Requires stable power supply and backup systems for critical utilities
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Maintenance service contract usually required
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Costs | -
High capital costs
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Costs of cobalt increased significanlty recently
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High capital costs
- High costs of backup
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High capital costs
- High costs of backup
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User acceptance | | | -
Low as technology is relatively unknown
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