Relaxation of compressive stress in gamma-irradiated Viton™ fluoroelastomer

•Ring samples of Viton™ a hexafluoropropylene-vinylidene fluoride co-polymer fluoroelastomer were compressed 25% and irradiated at room temperature in air to nominal absorbed doses of 10 – 106 Gy with 1.17 and 1.33 MeV gammas from a cobalt-60 source.•True stresses decline slightly from 1014±93 kPa at zero dose to 996±115 kPa at a dose of 103 Gy, decrease to 967±98 kPa at 104 Gy and then drop sharply to 640±116 kPa at 105 Gy and 157±32 kPa at 106 Gy.•Replacement of critical seals of Viton™ a at doses of about 105 Gy, and all seals at about 106 Gy or more, is prudent for vacuum systems exposed to ionizing radiation of any form.•Replacement of seals on pressurized systems is indicated for doses approaching, but less than, the dose at which true stresses estimated from our data equal the pressure differences across the seals. We report our study of stress relaxation of Viton™ A hexafluoropropylene-vinylidene fluoride co-polymer fluoroelastomer compressed 25% and irradiated at room temperature in air to nominal absorbed doses of 10 – 106 Gy with 1.17 and 1.33 MeV gammas from a cobalt-60 source. Our data show that the true stresses at room temperature in ring samples of Viton™ A fluoroelastomer compressed 25% decline slightly from 1014±93 kPa at zero dose to 996±115 kPa at a dose of 103 Gy, decrease to 967±98 kPa at 104 Gy and then drop sharply to 640±116 kPa at 105 Gy and 157±32 kPa at 106 Gy. We briefly discuss the implications of this data for the integrity of seals in high-radiation environments.