Summary Session Infrastructure and Operation P.Collier & Ph. Lebrun

Participation Quite a lively session 31 participants (8 from outside CERN) No structured set of presentations  Presented the proposed WBS  Presentation on the Geological study Went round the table to discuss the individual infrastructure systems and concepts to see the next steps  CE  Cooling/Ventilation  Survey  Cryogenics  Operation – Reliability  Safety –RP aspects  Safety systems  Cabling and electrical distribution

Civil Engineering – next steps ARUP presented their workplan: Stage 1: Development of geological model and GIS alignment decision aid tool Stage 2: Identification of key alignment layout optimisation requirements and constructability Stage 3: Refinement of above stages and establish concept for Pre-Feasibility Stage Stage 1: Feb 2014  June 2014 Stage 2: July 2014  Dec 2014 Stage 3: Jan 2015  May 2015

CE Discussion: Stage 1 is quite general – basic geology of the region Mentioned that other specific studies exist.  Several ideas – invited to contact John with possible links As we enter stage 2 there needs to be a limited number of options to study in more depth:  A requirements document is needed by early summer setting out the parameters of the (limited number of) options to study.  This could include constraints/requirements on:  the number of tunnels  Surface points/shafts  footprint/form of the machine  Inclination and planarity Preparation of such a document is the responsibility of the I&O coordination group  The timescale is rather short!!  Take into account all aspects including spoil at the relevant level of detail. Nothing is cast in concrete at this point – but we cannot study everything!!

Cooling & Ventilation General consensus concerning Ventilation  The maximum heat load should be taken by water cooling  The ventilation system should rather be determined by legislative requirements for access and safety  The length of sectors is important – but CV can actually help define or constrain this.  The use of multiple tunnels as mechanisms for ventilation needs to be elaborated.  Intermediate shafts – just big enough for CV and emergency access should be considered Water Cooling:  Cooling towers will most likely be required, but these are not so easy to sell to the general population  Possibilities for waste heat recovery – for the CERN surface installations?  Synchronization between production and need!!  Dumping heat into the tunnel surroundings? (CE models exist)  Use of Lake water discussed for part of the machine – but would this work if different temperatures were delivered to different parts of the machine?

Survey We need to extend the present CERN co-ordinate system!  Link the CERN system to the Swiss and French systems  Accuracy and quality of the data is different.  Minor inaccuracies here can have a major impact on the scale of FCC.  Number of access points is an important factor for the accuracy of the alignment! What are the constraints on the machine being at a specific inclination? What are the constraints on the machine being in a plane?? Alignment accuracy in the experiments  FCC-ee seems an extreme case with the mm beta*  Alignment of the machine to the detector – taking into account earth movements during and after excavation! FCC-ee seems to be the driver here!

Cryogenics A lot of basic scaling work has been done! Major areas of study:  Pushing the state of the art cryo-plant (presently ~25kW) versus the complexity of multiple plants.  Separate Cryo feedline?  Minimizing the He Inventory in conjunction with the magnet(RF) designers Location:  Nominally the 4.5K cryoplants would be on the surface and the 1.9K plants in the tunnel  But hydrostatic pressure is an important consideration here and the depth of the tunnel might be problematic  Discussion if we should consider underground intermediate caverns for infrastructure  Lower visibility on the surface  Still accessible during operation  Simplify hydrostatic pressure constraints.

Reliability General discussion on reliability of components, sub-systems, systems and the accelerator as a whole Consensus that this will be key to making the machine(s) work WBS contains WU on accelerator simulation that could help developing early fault detection and fault prevention scenarios. A model would need to be developed and could be fed with data from existing LHC monitoring data. Today we do not have the required analytics infrastructures to work on detecting patterns and correlations. Other labs can contribute to this LHC is the nearest in scale, but is a ‘young’ machine Tevatron attempted this kind of analysis and has a 25-year history of improvements and ‘tweaks’. Every facility has the same problem on different scales Tests, ideas and pilot schemes are directly applicable to operating facilities world-wide “We can study for the future while improving the reliability of our existing facilities”

Transport, handling Experience shows that redundant lifts would make life much easier!! Maintenance during operation also very desirable, Horizontal transport between shafts is a challenge if the distance becomes large Inductive powering systems look promising Monorail technologies are not advised if they are also to be used for the installation of large loads. Can envisage personal transport systems of 20-30km/h underground Should we consider an underground intervention system? Discussion on robotics/remote handling Clearly desirable in ’hot’ areas of the machine Less obvious for the rest. General survey/video remote facilities are clearly interesting everywhere. Design machine and systems with remote/automated intervention in mind from the beginning on

RP Issues Choice of materials is important to minimize activation Electronics gets more radiation sensitive as feature density increases. Possibility to have controllers close to machine, but radiation protected would be desirable Noted that the ee and the hh machines are very different: hh is very clean in the arcs – but not in the experimental SS and in the beam cleaning LSS ee is relatively clean in the LSS, all the main radiation is concentrated in the arcs! Need a simple study of the radiation field in the different cases. This can be refined as we make progress Basically looking at the impact on surrounding materials Input for the decision on the need for a service tunnel … a safety/access tunnel We need this for R2E Safe access Infrastructure installation

Conclusions Lots to do!!!!! External collaborators are keen to be involved! In the next 6 months we need to produce a requirements doc for the CE studies with a limited number of options!!!! Beginning of a consensus around the table that we cannot manage with a single tunnel! Still possibilities of a large split tunnel RP and safety will be the key factors here If the service and safety areas are sufficiently far away they can be accessible during operation of the machine. Reliability is considered as critical Not enough discussion on electrical distribution and surface vs. tunnel distribution of services.  Still, indications that a complete underground distribution of services might be necessary.