LHC Cryogenics Safety Training Day: Risks and Precautions

1. LHC HARDWARE COMMISSIONING SAFETY TRAINING DAY CRYOGENICS S. Claudet (AT-ACR-OP) With great help from G. Lindell (Safety commission)

2. Content • Introduction LHC Cryogenics - What are the risks ? • LHC strategy for oxygen deficiency hazards (ODH) Specification, procedures, Level 4 safety course • Cold surfaces and adapted behavior • Access restrictions during between 300 K - 80 K • Interventions on helium circuits (cryo work permit) • Summary LHC HWC safety training: Cryogenics

3. Helium @ 1.9 K LHC cryogenics architecture • Helium • Modularity • Single cryo line along the machine LHC HWC safety training: Cryogenics

4. Helium Ring Line Warm Recovery Line • Pressure vessels (code D2) with appropriate materials and safety devices • No Nitrogen in underground areas • QRL header D as large acceptance discharge line to avoid local discharges • No circulator underground LHC HWC safety training: Cryogenics

5. Risk duringoperation Adapteddesign Risk duringInterventions Major hazards associated with cryogenics (IS47) • Asphyxia: Oxygen is replaced by another gas (floor or ceiling depending on density) • Burns: Contact with cold surfaces could burn, (cold burns) as if it was hot surfaces • Explosion:After heating to ambient temperature, 1l of liquid will be at 700 atm or more • Materials:Material properties change radically with temperature: shrinkage, fragility + Interventions on part of the helium circuit: Could be under pressure, cold or about to be pressurised LHC HWC safety training: Cryogenics

6. Content • Introduction LHC Cryogenics - What are the risks ? • LHC strategy for oxygen deficiency hazards (ODH) Specification, procedures, Level 4 safety course • Cold surfaces and adapted behavior • Access restrictions during between 300 K - 80 K • Interventions on helium circuits (cryo work permit) • Summary LHC HWC safety training: Cryogenics

7. Oxygen Deficiency Hazards (ODH): risks LHC Project Report 523: Oxygen deficiency hazard (ODH) monitoring system in the LHC tunnel • Tunnel ventilation, curvature, alcoves • Worst case scenario analysis • Experimental studies, validation • Recommendations: detection + training LHC HWC safety training: Cryogenics

8. Oxygen Deficiency Hazards (ODH): Engineering specification LHC-SG-ES-0001 rev 4.0 EDMS 398629 LHC HWC safety training: Cryogenics

9. Oxygen Deficiency Hazards (ODH): Complement for specific cases LHC HWC safety training: Cryogenics

10. 21 % O2 18 % O2 ODH = Oxygen Deficiency Hazard (Lack of oxygen) 0 % O2 Oxygen Deficiency Hazards (ODH): Cryogenic safety level 4 course • Required for LHC HWC activities underground • Web based course available (incl. movie): SC’s home page / safety training / level 1, 2, 3 &4 and FAQ for help LHC HWC safety training: Cryogenics

11. Oxygen Deficiency Hazards (ODH): Cryogenic safety level 4 course LHC HWC safety training: Cryogenics

12. Content • Introduction LHC Cryogenics - What are the risks ? • LHC strategy for oxygen deficiency hazards (ODH) Specification, procedures, Level 4 safety course • Cold surfaces and adapted behavior • Access restrictions during between 300 K - 80 K • Interventions on helium circuits (cryo work permit) • Summary LHC HWC safety training: Cryogenics

13. T Condensation of water wet 0 C Ice Skin do not detach ! WHITE COLOUR Cold burns Cold burns • Surfaces could become cold • How to detect it could be dangerous: Condensation of air Simply avoid contact with cold « white » surfaces This also applies to “cold vapour clouds” and your lungs !!! LHC HWC safety training: Cryogenics

14. Limit at 80 K due to characteristics of thermal contraction of materials 1st Cool-down to 80K or Warm-up:Engineering specification LHC-S-ES-0003 rev 2.0 EDMS 615783 LHC HWC safety training: Cryogenics

15. 1st Cool-down to 80K or Warm-up • If required and validated by HWC coordinator as a must, blue token for doors could be granted from local cryo control rooms • Otherwise,access defined by HWC Engineering Specifications such as LHC-S-EC-00017 rev 1.2 (EDMS 848560) for S4-5 LHC HWC safety training: Cryogenics

16. Content • Introduction LHC Cryogenics - What are the risks ? • LHC strategy for oxygen deficiency hazards (ODH) Specification, procedures, Level 4 safety course • Cold surfaces and adapted behavior • Access restrictions during between 300 K - 80 K • Interventions on helium circuits (cryo work permit) • Summary LHC HWC safety training: Cryogenics

17. Cryogenic work-permit: When/ What for ? + Interventions on part of the helium circuit: Could be under pressure, cold or about to be pressurised • After the pressure test, interventions (opening, cut, welding) on helium circuits have to be secured by the cryogenic operation team. For this, a cryogenic work permit with corresponding consignation has to be issued • For purge, evacuation and pressurization of circuits which are not consigned, work permit is not required. (they are self protected) • The cryogenic work permit covers only risks related to pressure, cold burn and oxygen deficiency after the pressure test, when the initial circuit configuration is complete and the tunnel circuits are connected to the interconnection box. • For other risks (electrical, fire, …), relevant authorizations or consignations are required(a cryogenic work permit is necessary but not sufficient to safely weld on helium circuits of a DFB which has also electrical and fire hazard) LHC HWC safety training: Cryogenics

18. Cryogenic work-permit: stakeholders • The requester: Project Engineer (PE) or Installation Supervisor (IS) (according to the A9 safety code) is responsible for: • documentation and information supply (P&ID, drawings…) • Communication of the intervention completion. • The Intervention Team Leader (ITL) in charge of: • the work execution (CERN or sub-contractor). • The Operation Engineer (OE) (one per cryogenic island). Responsible for: • Definition and validation of the consignation procedure. • Execution of the consignation of the circuits • Communication of the consignation and deconsignation completion. LHC HWC safety training: Cryogenics

19. Cryogenic work-permit: how/where ? EDMS 754940 To be updated and finalised Point 2 (2007) Udo wagner + Jean-Paul Lamboy + SdC 79240/79241 Point 4 Udo wagner + Jean-Paul Lamboy + SdC 79440/79441 Point 6 Gérard Ferlin + Steffen Junker + SdC 79640/79641 Point 8 François Millet + Lionel Herblin + SdC 79840/79841 LHC HWC safety training: Cryogenics

20. Once you have applied the required procedures Summary • For LHC underground areas, be sure you have followed « cryogenic safety” level 4 course and that you know what to do in case ! • Never touch a cold « white » surface • Access is not systematic between 300 K and 80 K • Get a valid « Cryo work permit » prior to any intervention on a helium circuit Safety is often a matter of initiative and common-sense LHC HWC safety training: Cryogenics