The accelerator tunnels need to be made safe to allow particles to blast around the accelerator ring at energies above 7TeV, an energy target that will hopefully be reached by the end of this month.
Another, less hi-tech issue surrounds the copper sheaths that surround the superconducting joints through the tunnel. The copper sheaths are a failsafe feature that have been installed to prevent sudden heating of the electromagnets that collimate and accelerate the particle "beams" during operation. Engineers are concerned that they might not be sufficient to mitigate the risk of a future breakdown.
This sudden heating is known as a "quench," an old nemesis of the LHC. Back in 2008, during the first commissioning of the collider, a quench caused terrible damage to a section of magnets, physically ripping them from the floor.
Although this is most definitely a setback, the LHC will still be able to carry out science at energies never before harnessed by mankind for at least another 18 months. It may not be the 14TeV collision energies that the LHC has been designed to deliver, but 7TeV will still provide us with a glimpse of what this monster physics experiment can do.