High gamma dose tolerant glasses for vision systems in nuclear applications

For viewing systems to be used in highly radioactive environment, a comprehensive experimental study of optical lens glasses up to very high total gamma doses has been conducted, involving transmission degradation, temperature influence and surface corrosion analysis. The results obtained identify several materials with low optical transmission degradation and satisfactory properties for lenses fabrication. In particular pure silica and some stabilised glasses confirm their excellent behaviour even above the doses where they are usually applied. Other material, such as calcium fluoride or zinc sulphide, used for ultraviolet or infrared transmission show distinctive absorption peaks or even strong surface corrosion effects, leading in some cases to full opacity. Applicability of these glasses depend on the required bandwidth and on the development of suitable surface conditioning processes