The work performed and presented in this thesis forms a small part of a large, ongoing body of work currently being performed in France by the CEA in preparation of a dossier outlining possible strategies and processes for the reduction of the volume and radio-toxicity of high level nuclear wastes. In particular, this work has focussed on some elements and issues surrounding the option to transmute or incinerate high level nuclear waste pins in dedicated moderated target assemblies within an existing technology fast spectrum reactor. This approach enables the use of high fast reactor flux levels and high thermal neutron crosssections to optimise reaction rates within the target. In order to give some insight into the physics of llS4C, ZrH2 and CaH2 moderator materials within such an environment and provide initial validation of the deterministic fast reactor neutronics code, ERANOS, the COSMO series of moderated sub-assembly core experiments were performed in the MASURCA test reactor at CEA, Cadarache, France. This thesis has focussed on a calculational analysis of elements of the COSMO-I e IS4C moderator) and COSMO-3 (ZrH2 and CaH2 moderator) experiments which both contained moderated target sub-assemblies positioned at the centres of the simulated LMFR MASURCA core. It is important to note that the COSMO experiments did not contain any americium and as such were designed solely as a means to provide information on the physics of localised moderator materials within such a core and the development of appropriate calculational methodologies in support of the forthcoming ECRIX moderated target experiment in the PHENIX fast reactor. France. The work has demonstrated that ERANOS is suitable for calculations involving IlS4C moderators positioned at the centre of a fast reactor core but that a modification to the cross-section library generation routine will be required for cores containing ZrHz moderators to account for both the thermal incoherent inelastic and incoherent elastic scattering components at low energy. The same is not true for the case of a CaH2 moderator and existing scattering data based on hydrogen in water was found to be adequate. Contributions to discrepancies found to be due to 'ray' effects in the MASURCA geometry suggest that maximum detail is required in modelling such cores within and around the moderated assembly region.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:410882 |
| Date | January 2003 |
| Creators | Morris, Peter |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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