RRFM 2009 Transactions - European Nuclear Society

minor actinides (MA) considered as acceptable are 3% and 5% for the SFR and GFR,
respectively [7].
The incorporation of MA has some impact on the physico-chemical properties of fuel
material. Some results are available for the incorporation of MA in MOX fuel (smaller melting
temperature, influence of stoechiometry on thermal conductivity, redistribution of Am). But
additional data are needed to guarantee the safe operation of the reactor and fuel cycle
facilities (fuel fabrication and reprocessing).
The SUPERFACT irradiation in Phenix (1986-1988) represents the main body of existing
knowledge on the in-pile behaviour of MOX fuel loaded with MA. This demonstrated the
feasibility of MA incorporation up to 2% in (U-Pu-Am)O 2 et (U-Pu-Np)O 2 fuels (Figure 5).
Figure 5: SUPERFACT fuels (MOX fuels with or without MA)
SUPERFACT also showed that the addition of MA in significant quantity leads to increased
helium production which should be accommodated in the fuel design (fuel element free
volumes).
5. The qualification of innovative fuels
5.1 Phenix feedback experience
The Phenix fast sodium reactor resumed operation in 2003 after 6 years of a safety reevaluation
process. Authorization was granted for an operating period of 720 EFPD, which is
6 cycles of approximately 180 days of operation at 2/3 power. The reactor has had good
performance with availability factors at 74%, 85% and 78% in 2004, 2005 and 2006,
respectively. Good reactor operation has enabled both electricity production of and the
performance of irradiation programs according to the prescribed planning [8].
Phenix proved its excellent capability at performing experimental irradiations, owing to core
characteristics, operation flexibility, availability of hot cells for capsule mounting and postirradiation
examinations. More than 200 experimental irradiations have been realized in the
areas of MOX fuel and dense fuels (carbide, nitride) behaviour, clad and hexagonal tube
materials, transmutation of minor actinides (homogeneous and heterogeneous modes) and
of long-lived fission products, innovative fuel concepts and materials for 4 th generation
reactors,… Table 2 lists the experiments conducted in Phenix in the frame of irradiation
programs on transmutation and innovative systems.
The feedback experience gained from Phenix is considerable and has been very helpful at
identifying the areas to be further investigated for innovative fuels and reactor systems.
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