1 st LTEX meeting Protecting the experimental caverns and personnel from a "sector 34 like" incident: work planned in the LHC tunnel Prepared by M GASTAL with contributions from D HAY (EAM team), Christoph SCHAEFER (CMS Glimos), Nebojsa SMILJKOVIC & Jean BOS(CMS design office) and Giuseppe FOFFANO (Mechanical Design Office) 22/06/20091 Agenda: 1- Modifications in the CMS TAS regions 2- Sealing all remaining openings 3- Pressure resistant doors and ODH sensors

The CMS TAS region: an overview

CMS TAS is inside the Fixed Iron Nose FIN is fixed to Cubical Steel Frame Rotating Shielding closes around FIN Cubical steel frame Rotating Shielding Fixed Iron Nose The CMS TAS region: an overview

CMS TAS is inside the Fixed Iron Nose FIN is fixed to Cubical Steel Frame Rotating Shielding closes around FIN Cubical steel frame Rotating Shielding Fixed Iron Nose The CMS TAS region: an overview TAS

The CMS TAS region: an overview Fixed Iron Nose Rotating Shielding

The CMS TAS region: an overview TAS and its survey & alignment systems Modifications cannot prevent the TAS to be aligned in X and Y Inner triplet side

The CMS TAS region: an overview IP side

Modifications in the TAS region → Goals to achieve: → Restrict the TAS movements in Z during alignment → Prevent TAS movement in case of an September 19 th type of incident → Prevent a flow of He from the tunnel to propagate into the UXC55 → Avoid having to stay in the vicinity of the TAS once it is activated → E.g. alignment and removal operations → Limitations: → Stay clear of vacuum equipment → Keep a fixed point on tunnel side for TAS bake-out purposes → Keep the air flow around TAS for cooling purposes → Allow for a removal of the TAS during the phase 1 upgrade with minimal radioprotection risks → No machining in the tunnel if possible

Restrict TAS movements in Z Use of a spring to allow disengaging the TAS quickly, without using spanners, from a distance if using a stick No need to drill new holes Access to vacuum equipment remains the same Design to hold in case of 9/19 incident System will be compatible with CMS B field Pin provides a fixed point and prevent movement in Z

Seal TAS area (Option1) →~2cm of clearance between TAS & FIN →Cooling pipe has to remain accessible →Position of thermocouples and power cables connector to be respected

Annular clapper valve of a few mm of thickness Material to be stainless steal Allows air flow from UXC55 to tunnel Prevent air flow from tunnel to UXC in case of a 110mbar overpressure

Fixing of the clapper valve done using existing holes Thin seal will collapse when pulling TAS towards IP during Phase 1 upgrade removal

Seal TAS area (Option2) →Access only through UXC55, but it is more difficult because of the proximity of the vacuum remote handling system →Small leaks are still possible through TAS alignment and survey systems →Seal the volume on the IP side of TAS

Seal UXC55 from tunnel →Holes between the CSF and the FIN have to be closed →The resulting seal will withstand 110mBar →Existing seal is airtight but made of rock wool →New system uses metal plates and blocks filled up with concrete →Installation will not require access to tunnel but FIN doors will be open

Seal UXC55 from tunnel →FIN doors will be bolted and remaining gaps will be sealed by AGI

Seal UXC55 from tunnel →Examples of jobs done by AGI →All ducts, cables and cables trays will be sealed to guarantee 20Pa between Tunnel and UXC55

22/06/ /07/ Blast fire proof doors to sustain 110mbar All blast doors should open towards the incoming pressure Escape path for He Additional ODH sensors Remove existing door, include the UPX56 into the ventilated volume of the USC55 Change to fire proof door F90 Pressure resistant doors and ODH sensors

1 st LTEX meeting Protecting the experimental caverns and personnel from a "sector 34 like" incident: work planned in the LHC tunnel 22/06/ Conclusions: 1- Modifications in the CMS TAS regions: → To be done by end September 2- Sealing all remaining openings: → To be done by 26/06 3- Pressure resistant doors and ODH sensors: → To be installed by 15/07