Resistance to Ionizing Radiation

In certain modern technological facilities, such as nuclear reactors, nuclear fuel reprocessing plants, radiochemical laboratories, irradiation plants, etc., a large parts of the materials used in their construction is exposed to high radiation loads. Space craft are also irradiated to a considerable degree. This can cause undesirable, but unavoidable influences on the materials. 

The tailored use of irradiation to improve the properties of plastic materials facilitates radiation curing and radiation-chemical modification, and also serves for sterilization purposes in medical technology. 

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Bruno, A. P., Laurent, G., Blaise, R., Averbeck, D., Demur, C., Bonnet, J., Bettaieb, A., Levade, T., and Jaffrezou, J.P., 1998, Lack of ceramide generation in TF-1 human myeloid leukemic cells resistant to ionizing radiation. Cell Death Diff. 5 172-182. 

Lee JM, Bernstein A. p53 mutations increase resistance to ionizing radiation. Proc Natl Acad Sci USA 1993 90 5742-5746. 

One problem associated with the yeast 2-hybrid system is that protein interactions that are dependent on posttranslational modifications that can occur only in mammalian cells, would not be detected. For example, monoubiquitinylation and serine phosphorylation of a Fanconi anemia complementation group D2 protein (FANC-D2) are both required for mediating cellular resistance to ionizing radiation (122), an interaction that would be missed using this approach. 

The effect of irradiation of polymer membranes was studied by several research groups [1-7]. All studies showed that polymeric membranes exhibit limited resistance to ionizing radiation, however the threshold values of doses are sufficiently high to use the membranes for low and medium radioactive solutions treatment for a period of time. Usually the practical lifetime for most membranes is of the order of 4-5 years that is sufficient to avoid deterioration of hltration and separation abilities. Ceramic membranes are expected to be more resistant to y, (3, and a emissions, but systematic studies have not been presented. 

Replacing polymeric membranes by inorganic, more resistant to ionizing radiation and aggressive chemical environment... 

Elongation was better retained also by the addition of 5% soot to LDPE. The material underwent a rapid erosslinking at 50-60 kGy whieh improved its elongation by a faetor of 4. At the same time, its tensile strength was decreased by 30%." Polyethylene eontaining earbon blaek was found to be resistant to ionizing radiation. The impact strength of carbon black filled HDPE and HDPE/EPDM was improved after exposure to Y-radiation. ... 

Polyimides are sensitive to alkaline chemicals and will be dissolved by hot, concentrated sodium hydroxide. They are also moisture sensitive, gaming 1% in weight after 1000 hours at 50% relative humidity and 72°F (23°C). The polyimides exhibit excellent resistance to ionizing radiation and very low outgassing in high vacuum. 

Polyimides have excellent physical properties and are used in applications where parts are exposed to harsh environments. They have outstanding high-temperature properties and their oxidative stability allows them to withstand continuous service in air at tempera-tures of 260°C. Polyimides will burn, but they have self-extinguishing properties. They are resistant to weak acids and organic solvents but are attacked by bases. The polymer also has good electrical properties and resistance to ionizing radiation. A disadvantage of polyimides is their hydrolysis resistance. Exposure to water or steam above 100°C may cause parts to crack. ... 

Resistance to ionizing radiation. In contrast to chemically cross-linked elastomers, which change the properties and exhibit brittleness when exposed to electron beams or gamma rays, as a consequence of crosslinking or main chain scission, TPEEs are resistant to radiation doses up to 150 kGy. 

Datta, R, Manome, Y, Taneja, N, Boise, LH, Weichselbaum, R, Thompson, CB, Slapak, CA and Kufe, D (1995) Overexpression of Bcl-XL by cytotoxic drug exposure confers resistance to ionizing radiation-induced intern ucleosomal DNA fragmentation. Gell Growth Differ, 6, 363-370. 

Table 2.26 Regulations Relevant for Resistance to Ionizing Radiation...

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