Access conditions to new HL-LHC galleries during Run3

This year, it will finally become possible to descend to the underground areas of the HL-LHC by lift, at Point 5 before the summer season and at Point 1 in November. From these dates onwards, different teams will enter these areas on a regular basis to commence the installation of technical services such as lighting and electricity, ventilation, and a provisional alarm system. The full functioning of these services is a prerequisite for the following installation of accelerator-related hardware.

With the issue of easy access via the new lifts nearly solved, the next question arising is safety: under which conditions may I enter the HL-LHC underground areas, and how do I evacuate, in case of an emergency?

While at this time no access control point is yet installed at the surface of the HL-LHC shafts, it is nevertheless obligatory to register each intervention, even a technical visit, in the IMPACT application. This allows the activity coordinator and the safety coordinator to schedule the intervention for a time when it is the safest, by avoiding overlap with other activities (the technical term is “coactivities”). If work is planned, the safety coordinator will conduct a joint inspection (VIC) with those responsible for the teams involved.

Once the day and time of the planned access are nearing, do not forget the following PPE (personal protective equipment):

  • Safety shoes,
  • Safety helmet with frontal light,
  • High-visibility clothing (for example, a fluorescent waistcoat)
  • Self-rescue mask
Fig 1: Personal protective equipment (PPE)
Fig 1: Personal protective equipment (PPE)​

The safety coordinator may require other safety equipment after the risk assessment. Since the underground areas of the HL-LHC are shielded and isolated from LHC, a personal dosimeter is not required, not even when LHC is operating with particle beams.

At the end of an activity or a visit, how to get out: the standard answer is: “on the same way that you went in”. This means: cleaning up the worksite, not leaving any equipment in the way, walking back to the access shaft in the US cavern and taking the lift to the surface. End of a successful intervention!

However, every underground area has at least two independent exits in case one of the exits is blocked and cannot be used. In the HL-LHC, two independent emergency exits lead from the end of the UA tunnels to an evacuation route through the LHC tunnel. The key-word is EMERGENCY: the use of these exits would entail an immediate stop of the LHC accelerator, and the personnel who use them would receive a very small, but measurable, dose of ionizing radiation when following the emergency exit route through the LHC tunnel. So, in case that the regular lift from the US cavern to the surface is under heavy use or temporarily blocked, we kindly ask for your patience. You can communicate over the intercom to find out what to do in this case, most likely it is just an extended wait. Only in case of a dangerous emergency (smoke, fire, …) you are entitled to use the emergency exits.

An e-learning is presently under preparation by the HSE Safety Training service, until then the safety coordinator will provide you and your teams with all necessary instructions.

Fig 2: Standard exit paths from the new HL-LHC underground areas at Point 5
Fig 2: Standard exit paths from the new HL-LHC underground areas at Point 5