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Radiation Protection Issues After 20 Years of LHC Operation

Radiation Protection Issues After 20 Years of LHC Operation. D. Forkel-Wirth, M. Magistris , S. Roesler, C. Theis, L. Ulrici, H. Vincke, Hz. Vincke DGS-RP Malta, 15 th October 2010. HE-LHC from RP’s Point of View.

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Radiation Protection Issues After 20 Years of LHC Operation

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  1. Radiation Protection Issues After 20 Years of LHC Operation D. Forkel-Wirth, M. Magistris, S. Roesler, C. Theis, L. Ulrici, H. Vincke, Hz. Vincke DGS-RP Malta, 15th October 2010

  2. HE-LHC fromRP’s Point of View To convertLHC/HL-LHC into HE-LHC after 20 years of operationimplies: • exposureof workers to ionizing radiation • removal of dipoles • removal of inner triplets (?) • removal of collimators(?) • modification of beam dumps (?) • LHC experiment modifications/upgrades • installation of new components • radioactive waste • production • conditioning • interimstorage • final disposal

  3. Risk Analysis ..based on measurements

  4. Optimisation – Based on Outcome of Risk Analysis special devices dry-runs remote handling accomplishment

  5. LHC: forecasts on ambient dose equivalent rates can be only based on Monte Carlo simulations – comparison with measurements only later (LHC not yet very radioactive) Critical LHC Regions TCDQ/TCDS diluters TAS, TAN, Inner Triplet, dispersion suppressor

  6. Extrapolation of FLUKA results for nominal and 180 d of operation to 20 years of operation (including ultimate and HL-LHC) Fluka study Irradiation times: 180d, 5y, 20y Cooling times: 1d, 1w, 1m, 4m Materials of Cylinder: Iron (r= 7.874 g/cm3) Steel (r= 7.252 g/cm3) Protons@ 7TeV Iron or steel (radius: 24 cm, length:1m)

  7. Steel magnet, various irradiation times and 4 months cooling Irradiation time: 5 years Irradiation time: 20 years Irradiation time: 180 days E=7TeV • Assumption good enough for a reasonable extrapolation of ambient dose equivalent rates: • 20 years = 20 x 180 days irradiation, 185 days shutdown • removal of LHC accelerator components starts 4 months after beam stop

  8. Ambient dose equivalent rates along a steel magnet 20 years of operation: ambient dose equivalent rates are about a factor 2 higher when compared to 180 days of operation

  9. RP relevant LHC Parameters Assumption: no technical modification of LHC installations and no change of beam loss pattern -> ambient dose equivalent rates scale with beam energy (E0.8), with luminosity (experiments, Inner Triplet), beam intensity (arcs, collimators) and total number of protons

  10. Activation of Arcs Assumption: 2.4 × 104 protons/m/s (both beams), 7TeV, lost for 180 days continuously (corresponds to an H2-equivalent beam gas density of 4.5 × 1014 /m3) nominal 1 week 1 day 4 months 1 month ~20 uSv/h Aisle: ~200 nSv/h

  11. Activation of Arcs 2030 - after HL-LHC Assumption: 2.4 × 104 x ~1.5 protons/m/s (both beams), 7TeV, lost for 20 years operation (corresponds to an H2-equivalent beam gas density of 4.5 × 1014 /m3) 1 week 1 day times ~ 3 times ~ 3 4 months 1 month times ~ 3 ~20 -> ~ 60 mSv/h times ~ 3 Aisle: ~200 nSv/h -> ~600 nSv/h

  12. Inner Triplet Monte Carlo results for 180 days at nominal luminosity

  13. Collimators Aisle: 0.01-0.1mSv/h Close: 0.1-1mSv/h 2030 – after HL-LHC: Aisle: 0.03 – 0.3 mSv/h Close 0.3 – 3 mSv/h Monte Carlo results for 180 days of nominal operation, 4 months cooling

  14. Removal of Dipoles • Removal of dipolesimplies destructive work (cuttingbeam pipes, splices, etc.) and suchrisk of contamination. Adequate technique willbedevelopedduringspliceexercise in 2012. • Dose to workersduringdismantlingand transport needs to beoptimised: • avoiding Point 7 and Point 3 • dipoles out at Point 2 and Point 6? • new sidegalleries (?) • shieldedvehicles • remotecontrolledvehicles (?)

  15. Removal of Inner Triplet • Dismanlingimplies destructive work – experiencewillbegainedfrom the the first triplet exchange in some few years • The dose rates mayreach 500 uSv/h to 1 mSv/h after four months of cooling: major optimisation has to bedonewith respect to design, installation, removal and transport – validalready for the next Triplet generation and optimised design isimperative • material choice, • fastflangeconnectioninstead of welding? • adequatehandlingmeans to bedeveloped

  16. Removal of Collimators, Warm Magnets, etc. Ambient dose equivalent rates willbe in the order of some few 100 uSv/h to mSv/h - evenafter 4 months of cooling • Dismanling of collimatorshad been studied and optimised – development of remotehandlingtoolisongoing • Dismantling of warm magnets and passive absorbersneeds to beprepared and optimised – remotehandlingtools and special transport vehiclesneed to bedeveloped(alreadyrequired for the nextyears of LHC operation ) • Installingequipment in addition to the alreadyexisting, radioactive material in Point 3 and Point 7 seemsextremelydifficult if not impossible

  17. Waste Production Radioactive after 10 years of LHC nominal operation and 4 months of cooling 2030: LH-LHC, lower release limits ARC ? LSS7

  18. Waste Storage and Disposal • CERN’spresentinterimstorage for radioactive wasteisnot adapted to store LHC dipoles (cranes limited to 8 t). • « Light storage solutions for dipoles» need to bestudied • Radioactive wasteothersthandipolesneed to bestored in shielded areas equippedwithproperhandlingmeans • Wastestudy to define the eliminationpathway for dipoles (possible final repositoryCSTFA in Aube, today about 1000 Euros/m3) • The restrisks to stayat CERN waiting for final repository in France or Switzerland. Wastedisposal techniques and regulationmightevolveuntil 2030. CSTFA - 2033 Capacity: 750 000 tonnes Surface 48 h Storage 28,5 h

  19. Summary RP issues of HE-LHC are challenging • Exposure to workers during dismantling: • Much experience in removing components (dipoles, triplet, collimators) will be gained in the next few years, optimised dismantling will be required within the next years • Design of any new generation of components (like Inner Triplet) need to be optimised before being installed -> preparation for HE-LHC • Operation of HE-LHC will not increase the radiological risk to workers and public when compared to LHC-ultimate and HL-LHC (based on best present knowledge)

  20. Summary • Radioactive waste production, storage and disposal – needs to be addressed today as even small quantities of radioactive waste from LHC risk to pose a problem. • Moving from LHC to HE-LHC will double the amount of radioactive LHC waste , more options should be studied: • recycling of dipoles • “Magnet Disassembly Facility” to separate radioactive from non-radioactive material (if at all possible)

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