Development of advanced fuels. The needs for longer term R&D concerning fuel and relative fabrication processes are identified in the following areas: (i) oxide fuels with optimized microstructure, including fuels incorporating Pu coming from multirecycling and transmutation fuels, (ii) advanced carbide and nitride fuels and (iii) alternative fuel concepts (see Table 10). For each case dedicated irradiation testing will also be necessary in material testing or fast neutron reactors. Once removed from the reactor, PIEs must be performed. • Advanced oxide fuels development Powder metallurgy will still be the choice for first MOX fabrication plants, but co-conversion routes to generate MOX powder should be developed to reduce dust issues, enable optimised remote handling with degraded Pu vectors (and concomitant 241Am pollution due to 241Pu decay) when Pu multi recycling is established, and to achieve greater Pu homogeneity, enabling greater reliability and accuracy in properties, lower risk of hot spots under power, and a product more readily dissolvable to close the nuclear fuel cycle. Incremental process improvements can be made. In particular, a deviation (partial or complete) from traditional powder blending should be considered to yield a more homogeneous MOX fuel devoid of Pu rich regions, enabling a more uniform burnup and a material readily soluble under PUREX conditions. Such an evolutionary step can be achieved at the conversion stage at the recycling plant, where the U and Pu solutions are unified in a predetermined Pu enrichment. The (U,Pu) solution can be co-converted into a powder ready for further manipulation and processing into product pellets. Classical hydroxide precipitation is to be avoided as it results in a dangerous material – ammonium nitrate, which is explosive when dry. Other co-precipitation routes should be considered, for example (U,Pu) oxalate precipitation. Plant simplification and automation will play an important role too. The implementation of such processes can be accelerated if important issues pertaining to dust can be eliminated. Ideally the co-precipitation steps should result in an essentially dust-free powder, and should in an optimum situation not contain particles with diameters less than 20 µm aerodynamic diameter. Such particles should also be spherical or near spherical to ease their transport in the production lines. If dust can be eliminated, the potential for radiological pollution of the gloveboxes and the equipment therein can be reduced...
