  While a considerable and world-wide growth of the nuclear share in the global
energy mix is desirable for many reasons, there are also, in particular in the
"old world" major objections. These are both concerns about safety, in
particular in the wake of the Fukushima nuclear accident and concerns about the
long-term burden that is constituted by the radiotoxic waste from the spent
fuel. With regard to the second topic, the present contribution will outline
the concept of Partitioning & Transmutation (P&T), as scientific and
technological answer. Deployment of P&T may use dedicated "Transmuter" or
"Burner" reactors, using a fast neutron spectrum. For the transmutation of
waste with a large content (up to 50%) of (very long-lived) Minor Actinides, a
sub-critical reactor, using an external neutron source is a most attractive
solution. It is constituted by coupling a proton accelerator, a spallation
target and a subcritical core. This promising new technology is named ADS, for
accelerator-driven system. The present paper aims at a short introduction into
the field that has been characterized by a high collaborative activity during
the last decade in Europe, in order to focus, in its later part, on the MYRRHA
project as the European ADS technology demonstrator.
