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Commercial Aspects of Radiation Technologies
Radiation processing as a commercial technology began in the 1960s with early work on the crosslinking of polymers and the sterilisation of single-use medical goods with both electron beam and gamma rays. While these remain the two most popular applications today, the number and range of products treated with ionising radiation continues to grow year on year. The radiation processing applications split broadly into those which are based on the destruction of biological molecules (such as sterilisation, food sanitisation, and pest control) and those that produce beneficial effects in materials (such as polymer cross-linking, semiconductors, gemstones). In the case of the two main applications of sterilisation and polymer cross-linking, the radiation processes is a key manufacturing step which is critical to making the product fit for purpose and underpins the sale of billions of dollars of product per year. Based on the information gathered by IAEA there are over 350 such facilities operating today, with particularly high growth in the case of China which now operates as many industrial electron beam accelerators as the rest of the world put together! The three principle types of radiation used for product treatment are neutrons from reactors, gamma rays from cobalt-60, and electron and ion beams from particle accelerators. In recent years neutron treatments have declined due to difficulty in accessing the ever-decreasing number of research reactors and product activation issues. Gamma and electron beam dominate as they do not make the product radioactive and have been developed into reliable and cost-effective processes by companies such as MDS-Nordion and IBA. Cobalt-60 has excellent penetration into product, making uniform doses achievable and the process, is generally quite simple and reproducible. It does, however, require large quantities of the radioactive isotope cobalt-60, the transport and use of which has rightly come under additional scrutiny in the aftermath of 9/11. It is also a process that works best from an economic perspective if large volumes of products are treated in the same way. Electron beam on the other hand has speed and flexibility of dose delivery as major advantages but even with the continued developments in recent years accelerators remain relatively complex machines with high capital and energy costs. Outside of these main historical application areas development of new applications continues, particularly in niche market areas such as the treatment of semiconductors to introduce dopants through transmutation or to control carrier lifetime, for gemstones where permanent cosmetically attractive colour changes can be achieved, and in the production of specialist membranes for applications as diverse as fuel cells and blood filtration. Additionally there are a number of areas where radiation technology has the potential to be a low-energy, environmentally-friendly alternative to conventional treatment technology. For example waste water and industrial waste gases can be cleaned, cellulose can be extracted from wood and the curing step in composite material production are all possible using electron beam. A further mass market which has been in discussion for many years is the treatment of food. As a process, it is recommended by the World Health Organisation and large processing plants could treat product at a cost which would be acceptable to the market. However, consumer acceptance is an issue and the regulatory framework in many countries (particularly in the European Community) is difficult. The former Soviet Union has a large number of diverse radiation facilities including reactors, gamma irradiators and accelerators, with the majority dating back to the Soviet era (although there are notable exceptions). These divide into roughly two categories. There are a number of large, highly specialised, historic facilities with very high operational costs which are unlikely to be sustainable unless they are the critical resource in a special, very high added value process. The increasing rarity of research reactors in the West creates specific opportunities in this area for example. Additionally there are some more modest facilities, which are similar in scale and capability to those used for radiation processing in the West. Such facilities are already being used to meet the radiation processing needs of the domestic markets and CNCP is supporting projects facilitating the expansion of such facilities (in SOSNY, Minsk and KIPT, Kharkov for example). As application areas continue to expand and the economies of the CIS develop further these opportunities can only continue to grow. Dr Steve Sugden, | |
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