1. Helium spill in LHC tunnel
17/01/2013
He spill

2. Helium Spill Test in LHC tunnel Actual / Future situation
Actual situation: Restricted work area of 3 m, centred around release point (based on scale model);
Future situation?: Restricted work area of 12 m (9% of tunnel), based on scale model or
Restricted work area of 80 m (45% of tunnel), based on simulations
Large difference between result of studies
→ check with a real spill test
17/01/2013
He spill

3. Helium Spill Test in LHC tunnel Set-up of the spilling test
Liquid helium spill of 1 kg/s
Total spill per test 125 kg (= 1000 liquid liters)
Ventilation flow in access mode: m3/h, about 0.7 m/s in tunnel
(more tests foreseen)
1450 mm
DN 200
Equip the tunnel with measurement system
25 Temperature sensors (Pt100)
25 ODH (special development of fast reacting measurement head)
6 cameras
4 air velocity sensors
2 mass balances (used for calculation of mass flow)
Equipment will be placed within 100 m upstream and 200 downstream of release point
17/01/2013
He spill

4. Helium Spill Test in LHC tunnel Spilling test
Test foreseen for first week February, in sector 4-5, left of 5,
300 meter into arc, during night time
All equipment owners in the area where the spill test will find place, are asked to protect their sensitive material (electronic cards, connectors etc.) against condensation of water during the spilling test
Two conditions should be fulfilled during the test
Should have “reasonable” ventilation speed in the tunnel (as close as possible to nominal access conditions 0.7 m/s) > 0.2 m/s
Over pressure in CMS cavern so no helium will enter into the CMS cavern
17/01/2013
He spill

5. Test ventilation speed in sector 4-5 under test conditions
Close shielding between UL46 and UJ46
Close door in RB46
Close door between UA47 and RA47
Once the tunnel in this situation, a ventilation speed measurement will be made at test location. This ventilation speed can re-produced during test since we can re-create this same situation
Test Wednesday evening: ventilation speed at spill point: between 0.5 m/s and 1m/s (depending on height)
17/01/2013
He spill

6. Test overpressure CMS cavern
To close off the UXC55 cavern at least the following connections have to be closed:
UXC55 from tunnel (check beam tube and survey tunnels) and cap
USC55 from tunnel (closure of door betweenUSC55 and RZ54)
Once these modifications have been made a check of the capability to over pressurize (ideally 20Pa) the UXC55 cavern can be made.
Test Wednesday evening: overpressure of up to 31 Pa
17/01/2013
He spill

7. No showstopper identified up to now, so we continue the preparations:
Full seize spill (500 l) at surface (check of mechanical equipment and mass flow);
Installation of cabling and piping in tunnel
Equipment of test stands
Circulation of test procedure (at the moment being checked by Thomas Otto)
Sector 4-5 will be closed during week January 27th
17/01/2013
He spill

8. Access P5 during test week
Every test day, before test:
at 5 pm: shielding walls and ventilation doors closed at P4
at 8 pm: barriers put in place at
P4: RB46, UL46
P5: PM56, Q15L15, RR57
and
PM54 in closed mode
Patrol from P4 to RR57
Every test day, after test:
Fire brigade will make ODH check
Fire brigade will check conformity ODH, fire detection and alarm systems
Identification of eventual damages and contact with TI (piquet intervention)
Removal barriers at P4 and P5
Free access to PM54
In case of problems with ODH, fire detection or alarm system:
Only removal of barrier at P4
ASE intervention between 6 and 7.30 am
When problem solved, site coordination will remove barrier
17/01/2013
He spill