Context at P8

1
Context at P8
Last slide presented at LMC early May 2012
gt Delicate operation, 12hrs before getting to
the long 36 hrs recovery
2
21Sept12 - 1.8K unit for sector 81(78)
Faulty Heater 50 of flow generated
stopped, getting below minimum tolerated by CCs
Impossible to re-connect at low pressure without
it!
Decision to fill the pumping line to a pressure
compatible with reconnection at higher pressure
without the heater, But higher pressure means as
well higher temperature and long recovery!
3
Milestones

• During TS3, several strange effects on some
  instrumentation for this sub-system. Team
  investigating in cavern Friday when complete stop
  of 1.8K unit at 16h. 24VDC power unit found down,
  exchanged (medium term situation since 2010 with
  2-3 failures/year, type test ready, global
  upgrade gt LS1)
• Restart on tracks with sectors connected when
  400V heater failure stopped it again at 22h. As
  2nd time in 1 year, decision to go slowly without
  it (investigation to be foreseen when possible)
• 12hrs of delicate operation with control
  algorythm not correctly described, well mastered
  Saturday noon
• 36hrs of recovery for 2 sectors left without
  cooling for 18hrs

We will validate the 2nd refrigerator in the
coming days, and get
organised for diagnostic and repair of the heater
(window t.b.d)