Experimental durability studies of electrolysis cell materials for a water detritiation system

The radiation durability of the polymers in the solid-polymer-electrolyte (SPE) water electrolyzer of the water detritiation system (WDS) was investigated. A series of γ-ray and electron beam irradiation tests on the Nafion® N117 ion exchange membrane (a key polymer in the SPE electrolyzer, beyond the ITER-WDS requirement (530 kGy)) indicated that the Nafion® N117 membrane had sufficient radiation durability (up to 1600 kGy) with regard to the mechanical strength and the ion exchange capacity. To maintain the electrolysis function of the SPE cell up to 530 kGy, we suggest replacing the Teflon® insulator with a polyimide insulator. Any serious damage in the tensile strength of the Kapton® polyimide (up to 1500 kGy) was not observed during the γ-ray irradiation tests. Regarding the rubber material selection for the O-ring seal, we observed that the VITON rubber swelling in the water kept the tensile strength value constant (up to 1500 kGy). Moreover organic elution was not observed in the water after irradiation. With regard to its stable tensile strength and negligible organic elution, VITON rubber is a suitable material for the O-ring seal.