Use of vibro compacted MOX fuel in thermal reactors

The main business drivers for the next generation of reprocessing and fabrication plants will be cost reduction and diversion resistance. Integration of reprocessing plant with refabrication plant provides the scope to reduce powder handling stages prior to pelleting, e.g. by utilizing ammonium carbonate co-precipitation or thermal de-nitration to produce a U/Pu Masterblend for pelleting. The pelleting stage must be eliminated to achieve greater cost reduction, as this will also eliminate the requirement for grinding and pellet inspection and significantly reduce reject rates. Gel spheres have been vibro compacted into fuel pins and tested in fast reactors. Although this type of fuel was limited in rating and burn-up compared to annular pelleted fuel, the performance achieved far exceeds any requirements for thermal reactors. Co-finishing routes like gel sphere precipitation offer a measure of diversion resistance in that a pure plutonium stream need never be isolated. The lower smear density of this fuel has a similar effect to annular fuel in reducing the relative amount of 238U available for breeding and so increases the capacity for burning plutonium. Gel sphere routes, being essentially wet and dust free, will reduce dose and, being suitable for remote operation, lend themselves to finishing and fabrication of steams from reprocessing flowsheets offering lower decontamination factors (DFs). Lowering decontamination factors has a negligible effect on dose from fuel and on subsequent reactor performance but allows a substantial reduction in reprocessing costs. Incorporating fission products into fuels also assists in detection and diversion resistance. The acceptance of fuel with residual fission products, and the ability to finish and fabricate it, would provide scope for alternative reprocessing routes, such as pyrochemical methods, previously rejected on the grounds of failing to provide the decontamination attainable in the PUREX process. (author). 4 refs, 1 fig