Active and passive non-destructive measurements for fuel assemblies nuclear monitoring

The monitoring of spent fuel assemblies in reactor pools or in reprocessing plants with N.D.A. methods has a lot of interest (non destructivity, non intrusivity) for process control, safety criticality and/or nuclear material management. We present the new developments using active and passive methods (neutron and gamma) which allow the measure of these three physical parameters : Burn-up, cooling-time, effective multiplying factor and the qualification of these methods in an industrial context. (author)