Although cement is the material of choice for encapsulating hazardous nuclear waste, in some scenarios it suffers limitations. For instance, reactive metals corrode causing cracking of the wasteform while polymeric wastes, such as ion exchange resins, do not bind properly to the concrete causing it to crack. Amine cured epoxy resins have been proposed as an alternative encapsulant, which is not susceptible to these processes and will maintain the integrity of the wasteform for as long as possible in the geological disposal facility environment. Radiolytic and chemical degradation of the epoxy polymer matrix could potentially lead to leaching of small organic products into the groundwater. This leaching is problematic if the organic species are acidic or capable of acting as ligands to mobilise radionuclides.A group of four resin formulations have been considered; two pure and two commercially available. In order to test their suitability as nuclear waste encapsulants, the polymers were irradiated with cobalt 60 gamma radiation in a number of environments; pure water at pH 7 and saturated Ca(OH)2 solutions, in both aerated and deaerated atmospheres. Samples were also irradiated using accelerated helium ions. The polymers and contacting aqueous phase were analysed to determine chemical and physical changes in the polymer and the identity and quantity of species leached from the resin. There is clear evidence of organic species being leached from the resins including discolouration of the water and a significant increase in total nitrogen and organic carbon contents measured. Investigations into the identity of leached species are ongoing, employing ion chromatography and HPLC-MS.

Radiation resistance of novel polymeric encapsulants

248th National Meeting (2014)

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