Sterilizers electron accelerators

Irradiation. Although no irradiation systems for pasteurization have been approved by the U.S. Food and Dmg Administration, milk can be pasteurized or sterilized by P tays produced by an electron accelerator or y-rays produced by cobalt-60. Bacteria and enzymes in milk are more resistant to irradiation than higher life forms. For pasteurization, 5000—7500 Gy (500,000—750,000 tad) are requited, and for inactivating enzymes at least 20,000 Gy (2,000,000 rad). Much lower radiation, about 70 Gy (7000 tad), causes an off-flavor. A combination of heat treatment and irradiation may prove to be the most acceptable approach. 

The radiation field was surveyed for all possible types of sources that could be used for food sterilization. Since cobalt-60 and electron accelerators with energies greater than 5 m.e.v. showed the most promise, they were chosen. 

Cleland, M., O Neill, M.,Thompson, C. Sterilization with accelerated electrons. In Morrissey, R., Phillips, G.B. (eds.) Sterilization Technology A Practical Guide for Manufacturers and Users of Health Care Products. New York Van Nostrand Reinhold, 1993. 

The nuclear industry makes available about 3000 nuclides, including both the stable and the radioactive nuclides. Approximately 50 radioactive nuclides, along with some stable nuclides that have been isotopically enriched, are essential in research, medical, and industrial applications. Many of these are now produced commercially, but several still are dependent on government facilities. Some, for economic reasons, come from other countries. Radiation processing for sterilization of disposable medical supplies is an important operation using cobalt-60 from Canada. Electron accelerators have replaced... 

An accelerator is a device in which an electric field is developed by application of a voltage at opposite ends of a linear path. The greater the voltage, the faster the speed of the electrons the faster the speed of the electrons, the greater their penetrative power through matter. For practical sterilization purposes, accelerators of less than 100 MeV are being used for products such as hypodermic needles in which the requirement for penetration is minimal. 

Most of the irradiation in the field of sterilization is carried out by Co irradiation facilities however, sometimes electron accelerators are also used for this purpose. 

Both y- and electron radiation sterilization rely on ionizing energy, see Section 5.3. The energy source for electron radiation is an electron accelerator for y-radiation, radioactive isotopes (mostly CO) are used. 

Despite the serious criticisms against EtO related to toxicity and environmental aspects, sterilization using this gas, 100% or in various compositions, is one of the most widely used processes. Compared to alternative processes, EtO still remains a suitable choice than irradiation, because it promotes molecular alterations in different polymeric compounds, and it also causes long-term problems with the ramrods of Co, when its active life expires. Besides that, the irradiation with difficulties persists with accelerated electrons, in spite of the obtained improvements. 

UV irradiation can be used to eliminate viruses, especially airborne particles, by damaging viral nucleic acid, although again, small non-enveloped particles might be more resistant. Virus destruction can also be achieved by exposure to ionizing radiation (e.g. y-rays, accelerated electrons), which is used in terminal sterilization processes applied to pharmaceutical and medical products (Chapter 20). 

Several types of radiation find a sterilizing application in the manufacture of pharmaceutical and medical products, principal among which are accelerated electrons (particulate radiation), gamma-rays and UV light (both electromagnetic radiations). The major target for these radiations is believed to be microbial DNA, with damage occur -... 

Figure 1 7 0 MeV electron beam accelerator (Rhodotron with its scanned beam circled with the red line) in an EB/X-ray sterilization facility (courtesy ofIBA, Belgium).

X-ray Machine Sterilizers, Processors, and Particle Accelerators X-rays, protons, deuterons, electrons, gammas, Cesium-13 7, Cobalt-60 4 TBq to 40PBq Anywhere in an industrial area. Be aware of possible activation products. 

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