Polymeric seal degradation in nuclear power plants: Determination of physical and mechanical properties

Abstract

o assess the suitability of different materials as polymeric seals in the Nuclear Industry three commercial samples of nitrile rubber at grades BA40, BA50, and BA60 have been tested. Differential scanning calorimetry was used to find the glass transition temperature (Tg) and a Lloyds Texture Analyser 500 (TA500) was used to find the ratio of energy returned during relaxation against energy applied during compression. The mechanical properties determined from these experiments were then compared against the materials infrared spectra to infer structural characteristics. These were in turn cross-analyzed against the materials ability to swell in a liquid solvent and absorption behavior in a gaseous solvent. From this information, a statement could be made about each material's capacity to perform as a seal. It was thus found that the high energy retention and low absorption characteristics of BA40 made this material the best choice out of those studied for use as a polymeric seal in the nuclear industry

Experimental testing and numerical simulations for life prediction of gate valve O-rings exposed to mixed neutron and gamma fields

“…However, the behavior of these seals in the presence of intense neutron fields remains almost unknown; some of the most recent studies are still reporting results for gamma radiation only [8][9][10]. The effects of neutron radiations on gasket materials and structural components in general are quite undocumented compared to the effects of γ radiations.…”