FCC I&O Meeting

HSE Preliminary General Requirements for FCC layout and air managementA. Henriques & M. Widorski on behalf of the HSE Unit

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FCC I&O Meeting

Tunnel cross-sectionChoice of tunnel cross-section should respect the main Safety

requirements:

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Conventional Safety Radiation Protection

Personnel transportation for egressPersonnel 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 tunnelSingle Double

Larger tunnel diameter requiredSmaller 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)

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Ref: “CLIC Conceptual Design Report”, CERN-2012-007, Geneva 2012

FCC I&O Meeting

Tunnel cross-section1. Ideal solution: Double concept for the whole of the FCC

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FCC accelerator tunnel“Hazard Area”

FCC access tunnel“Safe Area” with personnel transport mean

FCC I&O Meeting

Tunnel cross-section2. Alternative solution: Double concept for high activation sectors

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FCC access tunnels to bypass high-radiation areas

FCC accelerator tunnel with “Safe Area” for egress:

Optimise area w.r.t. Safety

FCC I&O Meeting

Underground infrastructureTopic Requirement

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 facilities Radiation 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

Equipment Cooling of equipment should not rely on HVAC systems

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FCC I&O Meeting

Underground infrastructureTopic Requirement

Fire Fighting Ad-hoc and standard fire fighting and rescue equipment stored underground

Extinguishing system Automatic 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 zonesActivation Safe (shielded) storage areas for highly radioactive equipment removed from the accelerator and for important spare parts

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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

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FCC I&O Meeting

Air activationGeneral 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)

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FCC I&O Meeting

Air managementTopic Requirement

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

Confinement Compartmentalization 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;

Releases • Air 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 ?

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FCC I&O Meeting

Air management: Smoke extraction

Topic Requirement

Smoke extraction Proposal 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 1396658)10 km ~7 kPa

Smoke filtering Filtration or cleaning of extracted smoke shall be considered

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FCC I&O Meeting

Air management: Operating modes

Topic Requirement

In beam mode Determine 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 mode • Only flush the accelerator sectors to be accessed• Temperature, humidity and air renewal adapted to

occupational health requirements

In incidental situations • In case of fire stop the tunnel ventilation and start the smoke extraction

• Helium release same as fire (simulations still need to be done)

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FCC I&O Meeting

Air management: HVAC infrastructure

Topic Description

Operating parameters Extraction rates, temperature and humidity shall be controlled

Parameter monitoring Sufficiently dense monitoring network for temperature, humidity, pressure, air speed and oxygen level

Installation locations Install HVAC on the surface or in accessible locations

Stacks Sufficiently high stacks to be foreseen

Release monitoring All release stacks equipped for radioactivity monitoring

Redundancy Foresee redundancy for full or partial functions

Condensates Consider condensate collection and reduction infrastructure on the surface or in accessible locations

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FCC I&O Meeting

Summary

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• 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

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• 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 Meeting17/12/2014

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