Recycling in CANDU of uranium and/or plutonium from spent LWR fuel

Good neutron economy, a requirement for natural uranium fuelling, makes CANDU (CANada Deuterium Uranium) the most neutron-efficient, commercially available reactor in which to employ a range of fuel cycles. Additionally, on-line refuelling provides flexibility in fuel management in accommodating different fuels. A synergism with light-water reactors (LWR) is possible through the use in CANDU of uranium and/or plutonium recovered from spent LWR fuel. In the TANDEM fuel cycle, the uranium and plutonium recovered from spent LWR fuel are recycled in CANDU. This MOX fuel (mixed uranium/plutonium oxide), which is about 1.5% fissile, would give a burnup in CANDU of about 25 MW.d/kg HE. The amount of energy which can be extracted in CANDU by burning the uranium and plutonium recovered from spent LWR fuel is four times greater than that available from simply recycling the plutonium in a PWR. In this cycle there is no need to separate the uranium from the plutonium-an attractive feature from the non-proliferation viewpoint. Thus, instead of conventional reprocessing, a so-called chemical decontamination process could be used, which would also result in lower costs in a new plant designed for that purpose. In another fuel cycle, uranium recovered from spent LWR fuel during conventional reprocessing is recycled in CANDU. One advantage of recycling this recovered uranium (RU) in CNADU is that re-enrichment is not required. An RU enrichment of 0.9% in U-235 results in a CANDU burnup of at least 13 MW.d/kg U. When this fuel is discharged, the U-235 enrichment is around tails level, and there is no incentive for further recycling of the uranium. Because of the softer neutron spectrum in CANDU, the neutronic effect of U-236 is an order of magnitude lower than in an LWR. Twice as much energy can be extracted from the RU when recycled in CANDU rather than in an LWR. To fulfil the additional performance requirements of these and other fuel cycles employing enrichment. Atomic Energy of Canada Limited is developing the CANFLEX (CANDU Flexible Fuelling) advanced fuel bundle as the optimal carrier for all fuel cycles envisaged for CANDU. (author). 20 refs, 6 figs, 4 tabs