Post-irradiation embrittlement

The consequences of post-irradiation effects in polymer materials are progressive reduction in strength, cracking and embrittlement. Some reduction in these effects can be achieved by annealing of the trapped radicals, addition of appropriate... 

Microstructural Characterization of Reactor Pressure Vessel Steels Post-Irradiation Annealing Experiments Joint EPRI-CRIEPI RPV Embrittlement Studies (1999-2004), Electric Power Research Institute, Palo Alto, CA, 2004, 1003531, and CRIEPI, Tokyo, Japan, Q980401. 

Post-irradiation annealing results [55] suggest that microvoids or vacancy clusters are responsible for about 20-30% of the embrittlement effect in commercial RPV steels. Although such defects were detected in irradiated model alloys, there is no solid evidence for their detection in commercial RPV steels. 

The use of y-irradiation to sterilize polymers for medical applications requires careful stabilization of plastics such as polyolefins to prevent severe embrittlement. Most of this embrittlement occurs as a result of post-irradiation oxidative chain scission (1-4). Many stabilizer types have been investigated to minimize this problem in highly sensitive polymers such as polypropylene (2-7). 

Aging of an irradiated sample does not improve the mechanical properties they continue to deteriorate with time as seen in Figure 9. Post-embrittlement is caused by post-oxidation as a result of residual radicals and is discussed later (3). However, the oxidative reaction initiated by the irradiation cycle does not cease with irradiation but continues for long periods of time. 

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