Social and environmental justice for a growing and developing global population requires
significant increases in energy use. A possible means of contributing to this energy increase
is to incinerate plutonium from spent fuel of pressurised light water reactors (Pu(PWR)) in
high-temperature reactors such as the Pebble Bed Modular Reactor Demonstration Power
Plant 400 MWth (PBMR-DPP-400). Previous studies showed that at low temperatures a
3 g Pu(PWR) loading per fuel sphere or less had a positive uniform temperature reactivity
coefficient (UTC) in a PBMR DPP-400. The licensing of this fuel design is consequently
unlikely. In the present study it was shown by diffusion simulations of the neutronics, using
VSOP-99/05, that there is a fuel design containing thorium and plutonium that achieves a
negative maximum UTC. Further, a fuel design containing 12 g Pu(PWR) loading per fuel
sphere achieved a negative maximum UTC as well as the other PBMR (Ltd.) safety limits of
maximum power per fuel sphere, fast fluence and maximum temperatures. It is proposed
that the low average thermal neutron flux, caused by reduced moderation and increased
absorption of thermal neutrons due to the higher plutonium loading, is responsible for these
effects. However, to fully understand the mechanisms involved a detailed quantitative
analysis of the roll of each factor is required. A 12 g Pu(PWR) loading per fuel sphere
analysis shows a burn-up of 180.7 GWd/tHM which is approximately double the proposed
PBMR (Ltd.) low enriched uranium fuel burn-up. The spent fuel has only a decrease of
24.5 % in the Pu content which is sub-optimal with respect to proliferation and waste
disposal objectives. Incinerating Pu(PWR) in the PBMR-DPP 400 MWth is potentially
licensable and economically feasible and should be considered for application by industry. / MIng (Nuclear Engineering), North-West University, Potchefstroom Campus, 2012
| Identifer | oai:union.ndltd.org:NWUBOLOKA1/oai:dspace.nwu.ac.za:10394/10585 |
| Date | January 2012 |
| Creators | Richards, Guy Anthony |
| Source Sets | North-West University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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