COMPLETE DOCUMENT (1862 kb) - OECD Nuclear Energy Agency

As regards the fast spectra, results from experiments conducted in the Phénix reactor are
available. They concern, on the one hand, irradiations of separated samples (PROFIL 1 and PROFIL 2
experiments [146]), and, on the other hand, an integrated experiment (SUPERFACT) during which fuel
pins containing different neptunium and americium contents were irradiated [59].
As for the thermal and epithermal spectra, results from tests conducted on separated samples
of actinides are likewise available (SHERWOOD and ICARE experiments conducted at the
MELUSINE reactor). Furthermore, analyses of a number of experimental assemblies irradiated in
power reactors are also available.
Critical experiments conducted in the MASURCA (for fast spectra), EOLE and MINERVE
(for thermal spectra) reactors provided data on some minor actinide fission rates.
The fission products capture cross-sections were validated through oscillation experiments
conducted in the MINERVE reactor [147]. Tc rods were irradiated in the HFR reactor in Petten for one
year.
In the framework of the 1995-1998 Programme on Nuclear Fission Safety funded by the
European Commission, six companies and research centres are comparing their MOX irradiation data
banks with recalculations using modern methods and data, mainly from the JEF-2.2 file, so as to assess
the accuracy of systems studies on actinide transmutation involving the use of MOX fuels. The
experimental base comes from France (as detailed above), Belgium and Germany [148].
In fast reactor spectra, an irradiation of pure isotopic samples, similar to the PROFIL 1 and 2
experiments quoted above, was performed up to a maximum burn-up of 185 GWd/t in the KNK-II
reactor at Karlsruhe. The results, after verification by JRC-ITU Karlsruhe, will be used to extend the
data base.
For thermal spectra, while the CEA recalculates mass balances from MOX fuel irradiated in a
900-MWe PWR up to 46 GWd/tHM, the SCK•CEN Mol/Belgonucléaire group has compiled the
results of many MOX irradiations in various PWRs and BWRs; the maximum burn-up reached was
82 GWd/tHM in the BR3 reactor. Cross-section libraries mainly based on the JEF-2.2 file are used for
recalculations. Their checks and recalculations are backed by sensitivity analyses done in parallel at
ECN Petten.
A complementary activity of ENEA Bologna, in relation with CEA, is to re-evaluate basic
cross-section files for Pu and Am isotopes and to add photon production cross-sections.
The minor actinide nuclear data are measured for fission-neutron yields, delayed-neutron
spectra, and fission yields at JAERI in collaboration with the Oak Ridge National Laboratory (ORNL)
and Texas A&M University. Actinide nuclear data in the JENDL File are evaluated using the integral
experiments at the fast critical facility, FCA [149].
Fission cross-section ratios of minor actinide nuclides ( 237 Np, 241 Am and 243 Am ) relative to
235 U in the fast neutron energy region have been measured at YAYOI fast neutron source reactor [150].
Making use of back-to-back (BTB) fission chambers and a lead slowing-down spectrometer
coupled to a 46 MeV electron linear accelerator at Kyoto university, the fission cross-sections of 237 Np,
241 Am, 242m Am and 243 Am have been measured relative to that for 235 U(n,f) reaction in the energy range
from 0.1 eV to 10 keV [151].
173