LHC HARDWARE COMMISSIONING SAFETY TRAINING DAY

LHC HARDWARE COMMISSIONING SAFETY TRAINING DAY

S. Claudet (AT-ACR-OP)

With great help from G. Lindell (Safety commission)

CRYOGENICS

SC - 18 Oct'07 LHC HWC safety training: Cryogenics

Content• IntroductionLHC 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


QSCB

Sector 1-2 Sector 2-3 Sector 3-4 Sector 4-5 Sector 5-6 Sector 6-7 Sector 7-8 Sector 8-1

QSRB

QURA

QUIAQUIB

Point 4Point 2Point 1.8 Point 6 Point 8

Surface

CavernQURC

QSCA QSCA QSCB

QSRB QSRB

QSCB QSCAQSCA QSCB

QSRB

QURC QURC QURC QURC

QUIC QUIC

QURA

Shaft

QSCC QSCC QSCC QSCC QSCC

Tunnel

Storage Storage Storage Storage Storage

QURAQURA

Legend

Cryogenic Distribution Line

QSC_(A,B,C):QSR_(A,B):QURA:QURC:QUI_(A,B,C):

Warm Compressor StationSurface 4.5 K Refrigerator Cold BoxUnderground 4.5 K Refrigerator Cold Box1.8 K Refrigeration Unit Cold BoxCryogenic Interconnection Box

Commisionned & accepted

Under commissioning

Delivered / Under installation

Under fabrication

Ordered (Contract placed)

Under definition

Electrical Feed Box

Superconducting Link

QURC

QSCC

QSRA QSRA QSRA QSRA

QURC

QSCC QSCC

QURC

QUIC

LHC cryogenics architecture

Helium @ 1.9 K

- Helium

- Modularity

- Single cryo line along the machine


Warm Recovery Line

Helium Ring 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


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

Risk

dur

ing

oper

atio

nAd

apte

d de

sign

Risk

dur

ing

Inte

rven

tions

+ Interventions on part of the helium circuit: Could be under pressure, cold or about to be pressurised







• Summary


Oxygen Deficiency Hazards (ODH): risksLHC 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


Oxygen Deficiency Hazards (ODH): Engineering specification

LHC-SG-ES-0001 rev 4.0

EDMS 398629


Oxygen Deficiency Hazards (ODH): Complement for specific cases


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

ODH = Oxygen Deficiency Hazard(Lack of oxygen)

21 % O2

18 % O2

0 % O2


Oxygen Deficiency Hazards (ODH): Cryogenic safety level 4 course







• Summary


Cold burns

• Surfaces could become cold• How to detect it could be dangerous:

This also applies to “cold vapour clouds” and your lungs !!!

Condensation of air

Simply avoid contact with cold « white » surfaces

wet

Skin do not detach !Cold burns

WHI

TE

COLO

UR

Condensation of water

Ice

T

0 C


1st Cool-down to 80K or Warm-up:Engineering specification

LHC-S-ES-0003 rev 2.0

EDMS 615783

Limit at 80 K due to characteristics of thermal contraction of materials


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







• Summary


Cryogenic work-permit: When/ What for ?

• 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)

+ Interventions on part of the helium circuit: Could be under pressure, cold or about to be pressurised


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.


Cryogenic work-permit: how/where ?

EDMS 754940

To be updated and finalised

Point 2 (2007) Udo wagner + Jean-Paul Lamboy + SdC 79240/79241Point 4 Udo wagner + Jean-Paul Lamboy + SdC 79440/79441Point 6 Gérard Ferlin + Steffen Junker + SdC 79640/79641Point 8 François Millet + Lionel Herblin + SdC 79840/79841


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

Once you have applied the required procedures

Safety is often a matter of initiative and common-sense

LHC HARDWARE COMMISSIONING SAFETY TRAINING DAY

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