The generation of nuclear energy leads to the generation of contaminated, radioactive wastes. The current strategy in the UK is to dispose of high and intermediate level wastes to a geological disposal facility with no possibility for retrieval. The waste is contained in an encapsulation matrix, which is usually cement, however cement is unsuitable for certain waste types, for which epoxy resins have been proposed as an alternative. The radiation resistance of two candidate epoxy/amine resin formulations under repository conditions were tested with regards to the degradation of the backbone structure and the release of potential organic ligands from the polymer. The difference in the polymers was the choice of amine curing agent. Analysis of the polymer by infra-red spectroscopy and nuclear magnetic resonance spectroscopy revealed that the carbon nitrogen bonds are the most susceptible to radiation damage, regardless of the atmospheric and aqueous environment. The presence of an aqueous phase greatly reduces the availability of oxygen and reduces the rate of degradation when irradiated under an atmosphere of air. The properties of the aqueous phase has little effect on the degradation of the polymer. Thermal analysis revealed that the effects of the environment are limited to a thin surface layer of the polymer. Leachate analysis revealed that both organic and nitrogen containing compounds are leached from the polymer when irradiated in pure water. Under repository conditions however very little carbon and nitrogen is observed, suggesting that the calcium hydroxide present in repositories is capable of removing the leached species from solution. The generation of nitrate ions from air radiolysis over water is suppressed in the presence of the polymers, suggesting that nitrate is removed from solution by leached species or reaction with the polymer.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:654802 |
| Date | January 2015 |
| Creators | Barr, Logan |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://www.research.manchester.ac.uk/portal/en/theses/radiation-resistance-of-novel-polymeric-encapsulants(4a16b78f-f810-407d-815f-db63027aa014).html |
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