HSE Preliminary General Requirements for FCC layout and air management A. Henriques & M. Widorski on behalf of the HSE Unit 17/12/2014 FCC I&O Meeting

Tunnel cross-section Choice of tunnel cross-section should respect the main Safety requirements: 17/12/2014 Conventional SafetyRadiation Protection Personnel transportation for egress Personnel transportation for short transit times between access and intervention point “Safe zone” in the tunnel (fire resistant, air/gas tightness and in ‘overpressure’) Parallel service tunnels along all potential high-activation sectors Air management aspects FCC I&O Meeting

Single vs. Double tunnel SingleDouble Larger tunnel diameter required Smaller tunnel diameter, in total more space available to integrate/handle infrastructure Larger air volume will lead to higher activity levels Smaller air volume will lead to a lower total activity. Fire resistant and ODH proof passage for egress (with dedicated ventilation) Optimised separation of hazards (activation, cryo, electricity, heavy equipment transport) from evacuation and passage ways Frequent passage doors between “Safe Area” and tunnel (min. every X meters) Frequent passages between both tunnels (min. every Y meters) 17/12/2014 FCC I&O Meeting Ref: “CLIC Conceptual Design Report”, CERN , Geneva 2012

Tunnel cross-section 1. Ideal solution: Double concept for the whole of the FCC 17/12/2014 FCC accelerator tunnel “Hazard Area” FCC access tunnel “Safe Area” with personnel transport mean FCC I&O Meeting

Tunnel cross-section 2. Alternative solution: Double concept for high activation sectors 17/12/2014 FCC accelerator tunnel with “Safe Area” for egress: Optimise area w.r.t. Safety FCC I&O Meeting

Underground infrastructure TopicRequirement Personnel transport and evacuation Personnel transport system for fast transfer between access point and intervention locations and for fast evacuation Equipment transport Autonomous transport devices for equipment and material distribution (“Dispatch service”) Remote inspection and handling Prepare infrastructure for remote handling of highly radioactive equipment Integrate remote inspection devices Sanitary facilitiesRadiation Safe areas for sanitary facilities Tunnel walls Tunnel surfaces shall be treated to minimise dust production and limit tritium releases from concrete Potential need for a cooling system for rock heating and wall insulation EquipmentCooling of equipment should not rely on HVAC systems 17/12/2014 FCC I&O Meeting

Underground infrastructure TopicRequirement Fire Fighting Ad-hoc and standard fire fighting and rescue equipment stored underground Extinguishing systemAutomatic extinguishing systems for early fire attack Fire and smoke compartments Compartmentalization (walls or curtains) to facilitate evacuation and intervention and to limit the extent of damage. Lifts Feasibility with respect to Safety requirements be clarified for expected depth Storage/Buffer zones Activation Safe (shielded) storage areas for highly radioactive equipment removed from the accelerator and for important spare parts 17/12/2014 FCC I&O Meeting

Tunnel & shafts location Maintain minimum distances to lake bottom and underground infrastructures Hydrogeological optimisation to prevent ground water activation Place air release sites in less densely populated areas to minimise impact from air- borne radioactivity Environmental impact on the surface sites 17/12/2014 FCC I&O Meeting

Air activation General considerations on the radiological impact by radioactive air: The total released activity and activity concentration is determined by the air exchange rate and the effective decay time of the air before being released For the environmental impact, only the total released activity is of concern. For the exposure of workers surrounded by activated air only the activity concentration is of concern. Known beam loss locations may be shielded to minimise air activation (dumps, collimators, forward shielding at interaction points) 17/12/2014 FCC I&O Meeting

Air management TopicRequirement Transverse vs. Longitudinal ventilation Transverse ventilation does not offer advantages without shielded ducts, therefore longitudinal ventilation is a viable option if the smoke/ODH extraction proposal is implemented ConfinementCompartmentalization between high activation, low activation and no activation sectors Static: air tightness in the civil engineering and sealing cables, ducts, piping, etc. Dynamic: pressure difference between compartments with different activation sectors; ReleasesAir from high activation sectors should be released at distant outlets to maximise the decay time Release points shall be placed in less densely populated areas Could air compression or condensation be a technical option for temporary decay storage ? 17/12/2014 FCC I&O Meeting

Air management: Smoke extraction TopicRequirement Smoke extractionProposal presented to I&O in July 2014: Limit propagation and contamination of smoke to others volumes of the tunnel Provide the dynamic confinement Reduced cross section of the ducts compared to transverse ventilation Linear pressure drop for 8 km  ~5 kPa (EDMS ) 10 km  ~7 kPa Smoke filteringFiltration or cleaning of extracted smoke shall be considered 17/12/2014 FCC I&O Meeting

Air management: Operating modes TopicRequirement In beam modeDetermine optimal extraction flow-rate considering: Release of short lived emitters Accumulation of long lived emitters Tritium concentration in condensates Guarantee sufficient confinement Operational parameters (temperature, humidity, air speed) In access modeOnly flush the accelerator sectors to be accessed Temperature, humidity and air renewal adapted to occupational health requirements In incidental situationsIn case of fire  stop the tunnel ventilation and start the smoke extraction Helium release  same as fire (simulations still need to be done) 17/12/2014 FCC I&O Meeting

Air management: HVAC infrastructure TopicDescription Operating parametersExtraction rates, temperature and humidity shall be controlled Parameter monitoringSufficiently dense monitoring network for temperature, humidity, pressure, air speed and oxygen level Installation locationsInstall HVAC on the surface or in accessible locations StacksSufficiently high stacks to be foreseen Release monitoringAll release stacks equipped for radioactivity monitoring RedundancyForesee redundancy for full or partial functions CondensatesConsider condensate collection and reduction infrastructure on the surface or in accessible locations 17/12/2014 FCC I&O Meeting

Summary 17/12/2014 Tunnel cross-section - Ideal solution: Double tunnel - Acceptable solution: Tunnel to bypass high radiation zones + transport mean inside the “Safe Area” Underground infrastructure - Personnel & equipment transport means - Shielded storage areas - Fire compartmentalization - Rescue equipment stored underground Tunnel & shafts location - Assess environmental sensitive areas - Hydrogeological study - Extraction points in less densely populated areas FCC I&O Meeting

Summary 17/12/2014 Air management - Longitudinal ventilation + smoke/ODH extraction proposal is a viable option for ventilation - Static and dynamic confinement different activation and fire sectors - Optimise extraction to maximise the decay time - Filtration of smoke - During beam mode: optimise extraction flow-rate - During access mode: Only flush the accelerator sectors in access mode FCC I&O Meeting

17/12/2014 Spare Slides FCC I&O Meeting