  The HIE-ISOLDE project represents a major upgrade of the ISOLDE nuclear
facility with a mandate to significantly improve the quality and increase the
intensity and energy of radioactive nuclear beams produced at CERN. The project
will expand the experimental nuclear physics programme at ISOLDE by focusing on
an upgrade of the existing Radioactive ion beam EXperiment (REX) linac with a
40 MV superconducting linac comprising thirty-two niobium-on-copper
sputter-coated quarter-wave resonators housed in six cryomodules. The new linac
will raise the energy of post-accelerated beams from 3 MeV/u to over 10 MeV/u.
The upgrade will be staged to first deliver beam energies of 5.5 MeV/u using
two high-$\beta$ cryomodules placed downstream of REX, before the energy
variable section of the existing linac is replaced with two low-$\beta$
cryomodules and two additional high-$\beta$ cryomodules are installed to attain
over 10 MeV/u with full energy variability above 0.45 MeV/u. An overview of the
project including a status summary of the different R&D activities and the
schedule will outlined.
