IAEA activities in the area of thorium based nuclear fuel cycles

In the framework of IAEA activities Implementing Thorium in Nuclear Fuel Cycles is one of the challenging topics. Incentives for Th-based fuel cycles (vs. U-Pu cycles) are: 233-U breeding capability due to its higher neutron yields in thermal and epithermal regions in Th-233-U cycle; Large Th deposits in some countries; Potentials for fuel cycle cost reduction, 235-U enrichment reduction, safer reactor operation due to lower excess reactivity requirements, safer and more reliable ThO2 fuel at high burnup, potential benefits for reducing Pu production and higher actinides. Disadvantages for Th-based fuel cycles (vs. U-Pu cycles) are: More difficult fuel handling due to its stronger gamma radiation level (228-Tl: strong gamma emitter) - preferable for nonproliferation, more complicated fuel cycle mechanism, longer spent fuel cooling due to higher residual heat, potential difficulties in down stream spent fuel reprocessing. 'New' potential benefits for reducing Pu production and higher actinides are emerging. Coordinated Research Projects (CRPs) 'Potential of Thorium Based Fuel Cycles to Constrain Plutonium and to Reduce Long Lived Waste Toxicity' and 'Use of Thorium Based Fuel Cycles in Accelerator Driven Systems to Incinerate Plutonium and to Reduce Long-term Waste Toxicities' were completed. The following were published: assessment of thermo physical and thermo- hydraulic characteristics of lead, lead-bismuth, and sodium coolants for fast reactors (IAEA TECDOC-1289); Thorium fuel utilization: Options and trends (IAEA TECDOC-1319); Power Reactor and Sub-critical Blanket Systems with Lead and Lead-Bismuth as Coolant and/or Target Material (IAEA TECDOC-1348) Potential of thorium based fuel cycles to constrain plutonium and reduce long lived waste toxicity (IAEA TECDOC-1349). 35th and 36th TWG-FR Meetings recommended to convene a Consultancy to recommend topics for a CRP at investigating the potential benefits of Thorium fuels