1. Hazards for Personnel during Commissioning
Paul Proudlock

2. Acknowledgements
Ralf Trant
Gunnar Lindell
Fritz Szoncso
Marc Vadon
Ghislain Roy ……
who all said they would be delighted to give the talk but would be absent.
Then Robin changed the date!
I’ll try to give a summary with a few of my own views thrown in
Thanks also to;
David Nisbet and Robin Lauckner and anyone else I annoyed

3. Pre-amble
Commissioning is by nature a hazardous stage for equipment and personnel;
First time many systems are brought into service and their interactions observed
Procedures, although well studied, may need further development or we may discover we need new ones
The unexpected or unknown may well arise
Protection systems need to be tested and calibrated
Further;
Commissioning will be carried out while installation and other activities are going on elsewhere in the machine
Activities are changing; Installation  cool-down  powering
You can’t necessarily do what you ALWAYS did in the past
Non-experts may be invited to work within the commissioning zone (or worse, try to gain access to it without being invited!)

4. What do we need in order to start?
The best possible access restrictions and control
This will not be at the level we will have when the machine operates
interlocking, identification levels, restricted data bases…
We will have to use additional measures
Strictly NO TOURISTS
Restrictions will vary according to what is going on, e.g.1st powering of MB
Everyone must be aware of the hazards and risks and must have taken the training up to Level 4
Refresh your memory, have a look again; you don’t have to take the test !
The established safety procedures must be followed
All systems must have been inspected and accepted by SC
All activities must be co-ordinated through the HC Team and carried out by personnel competent in the task and aware of the hazards

5. So what are the Dangers?
Those associated with being underground in general
The need for fresh air
The risk of fire, flooding….
The difficulty of evacuation
You may find yourself a long way from an exit point
SO!
Make sure you know;
How to get around. Understand the geography! (very important)
Where are the “safe areas”
The safety systems and how they function
What to do and who to call in an emergency
If you don’t know – Find out or ASK

6. So what are the LHC specific Dangers?
With the exception of the Main Dipole, the superconducting circuits of LHC use Low Voltage to power them.
However,
There are dangers from the large currents
And more importantly there are particular dangers from the release of stored energy, particularly in an uncontrolled fashion!
Deliberate or accidental interruption of the current in the superconducting circuits will cause high voltages and arcing.

7. Therefore you should be aware that;
High voltages are developed during energy extraction (Deliberate insertion of a resistor in the circuit to cause rapid current decay). The audible noise level close to these devices, and particularly those associated with the Main Dipole circuit, will be high.
An accidental interruption due to equipment failure or intervention on the circuit will or could cause;
Arc UV
Explosion
Debris
Pressure waves
Fire
Smoke ….
Words of Fritz Szoncso

8. SO
Do not disconnect any part of a circuit unless it is clear that there is no current flowing and therefore no stored energy.
Procedure EDMS must be followed.
VAC, Validation of Absence of Current
Do not stand next to the extraction switches; you might get a surprise when they open.
Be equally wary of the DFBs

9. Are there other Electrical Dangers in LHC
YES,
All those associated with AC distribution
Conventional warm magnets
The QPS heater supplies
Injection and extraction systems use High Voltage kickers but are well shielded,
Generators,
PFN,
Capacitor banks,
Kicker magnets

10. Other Electrical and RP Dangers for Commissioning
The RF System at point 4
HV for Klystrons and other drives
HV Bunkers strictly out-of-bounds
Radiation from Cavities, particularly during conditioning
For any question, contact radiation protection (SC/RP): Isabel BRUNNER,

11. New Generation of Power Converters
The new generation of Switch-Mode Power Converters work at frequencies above audible level
They do not hum, vibrate and rattle like the “old” ones
SO, it is not immediately obvious whether they are ON or OFF
Don’t assume they are off just because there is no noise.

12. Oxygen Deficiency Hazard
LHC cryogenic layout
Level 4 Training
There will be large quantities
of helium (liquid & gas) in the
LHC tunnel for cooling down
parts of the accelerator
(about 800’000 litres).
The biggest quantities will
be found in:
Helium ring line (gaseous)
- The cryogenic distribution
ring line (QRL)
The magnet cold mass

13. Oxygen Deficiency Hazard
Risks in the event of a big helium release
Asphyxiation
--> low concentration of oxygen (O2)
(The liquid helium will evaporate to gas, which will displace the air)
Cold burns on skin and in lungs if inhaled
--> helium at -271ºC (1.8K)
Level 4 Training

14. Oxygen Deficiency Hazard
Level 4 Training
Conclusion
Warnings
Vapour cloud
Helium release
Red flashing light
Noise of rushing gas
Evacuation sirens
What to do
Crouch down
Put on oxygen mask
Evacuate away from
the helium release
Do not walk in to
a vapour cloud.
Alert

15. Emergency Stop
Be aware that not all equipment is shut down by the AUG (e.g. QPS)
The AUG does not cut equipment marked with orange stripes

16. A few comments for the CCC personnel
This is the first Commissioning Stage
Mixed activities
Learning how to do it properly and safely
Extra caution needed
Make full use of experts
The HC team are overall responsible and co-ordinate all activities
Roles and responsibilities must always be defined before an action is undertaken

17. Glossary Level 4 Training Disconnection procedure Kicker Systems
RF Systems
HV Bunkers
Emergency Stop