Review of Sector 45 - 28th of February 2008 1

Tunnel Access During Powering Tests

Hugues Thiesen, AB-PO

Review of Sector 45 - 28th of February 2008 2

Sector layout

Tunnel

QRL

ARCMLIT MR

RRUAPM PM

Mac

hine

Acc

ess

Mac

hine

Acc

ess

LHC surfaceaccess

LHC surfaceaccess

Sector layout

Review of Sector 45 - 28th of February 2008 3

Hazards in the tunnel

Different Hazards Radiation

Beam RF system

Electricity PCs QHPSs Instrumentation DFBs and theirs proximity equipments Cryo magnets

Cryogenic DFBs Cryo magnets QRL

Review of Sector 45 - 28th of February 2008 4

Radiation Hazards

Radiation risks Irradiation (beam or RF system)

Alpha, beta, etc.. Depend only of the area status, not of the powering tests

RB injection current is 760A (< 1kA) Access

No access when the sector is closed Control of the access

LHC access system (Doors and EIS)

NO ACCESS IN THE AREA WHEN IT IS CLOSED

Review of Sector 45 - 28th of February 2008 5

Electrical Hazards

Electrical risks Electrocution or burn

By touching a metallic part (active or not active)By an electrical arc (initiated by a metallic tool)

Do not depend of the current but only of the conformity of the equipmentsAt 350A the output voltage of the RB could be 160V

The electrical risks DO NOT depend on the current but only of the electrical conformity of the

equipments

Review of Sector 45 - 28th of February 2008 6

Electrical risks The electrical equipments have to be conform at the 15-100 standard (code C1)

Metallic parts have to be correctly grounded (DFB, cryo magnets, etc..)

Active parts have to be protected again direct contacts (IP2X)

Electrical Hazards

Review of Sector 45 - 28th of February 2008 7

Electrical risks Electrical inspection realized by AT/AS3 (Guy Salomon)

Electrical Hazards

The group/department must request the inspection after the installation and before the powering tests

The group/department is responsible of the conformity of its equipments

Review of Sector 45 - 28th of February 2008 8

If the equipments are not conform? Grounding

Always mandatory Electrical Protection IP2X

Fencing + flashing lightsB0V/H0V

Electrical Hazards

Review of Sector 45 - 28th of February 2008 9

Cryogenic Hazards

Cryogenic risks Asphyxia

Opening of the safety valveRupture of a cryogenic pipe

Cold burnOpening of the safety valveRupture of a cryogenic pipe

ExplosionRupture of a cryogenic pipe

Cryogenic risks vs Powering tests No powering tests

Access in the tunnel is restricted when the cool down is finished (see Serge Claudet presentation “Safety during HC” 18 October 2007)

Powering testsRisk of quench -> opening of the safety valve and/or rupture of the

cryogenic pipe (depend on the current in the circuit)

Review of Sector 45 - 28th of February 2008 10

Cryogenic Hazards

Powering tests of the corrector magnets (60A to 600A circuits) The energy stored in the magnet is not enough to created additional risks

(has to be confirmed by MPP and AT-ACR) Access in the tunnel is restricted

Powering tests of the main magnets (MB, MQ, IPD, IPQ and IT) The magnets do not quench below 1 kA (has to be confirmed by MPP) Access in the tunnel is restricted if the current is below 1kA above 1 kA ?

Review of Sector 45 - 28th of February 2008 11

Cryogenic Hazards

Powering tests of the main magnets above 1kA Limited asphyxia risk beyond 2 m (has to be confirmed by MPP/AT-ACR)

Limited Cold burn risk beyond 2 m (has to be confirmed by MPP/AT-ACR)

Limited explosion risk beyond the half sector (has to be confirmed by MPP/AT-ACR)

Review of Sector 45 - 28th of February 2008 12

Cryogenic Hazards

Powering tests of the main magnets above 1kA

IPD.L, IPQ.L (arc magnets included) or IT.L => no access in the left part of the sector (C1L to C34L) IPD.R, IPQ.R (arc magnets included) or IT.R => no access in the left part of the sector (C1R to C34R) MB, MQD or MQF => no access in the tunnel

QRL

ARCMLIT MR

RRUAPM PM

Mac

hine

Acc

ess

Mac

hine

Acc

ess

LHC surfaceaccess

LHC surfaceaccess

Review of Sector 45 - 28th of February 2008 13

Conclusion

Hazards in the tunnel Radiation hazards

Do not depend of the powering tests but only of the area statusRisks managed by the access systemAccess is forbidden when the machine is closed

Electrical hazardsDo not depend on the current levelThe electrical equipments in the tunnel have to be conform at the 15-100 standard (grounding, direct contacts protection, etc…) If the equipments are not IP2X, compensatory measures have to put in place

Fencing + flashing light or electrical screen Habilitation B0V/H0V

Access is restricted access

Review of Sector 45 - 28th of February 2008 14

Conclusion

Hazards in the tunnel Cryogenic hazards (< 1kA)

No additional risks if the current is less than 1kARestricted Access

Cryogenic hazards (> 1kA)Forbidden Access

IPD.L, IPQ.L (arc magnets included) or IT.L => not access in the left part. IPD.R, IPQ.R (arc magnets included) or IT.R => not access in the left part. MB, MQD or MQF => not access in the tunnel

Have to be confirmed by AT

General conditions Access must be ONLY given by the CCC for the tests team