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VERSION:2.0
PRODID:-//CERN//INDICO//EN
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SUMMARY:Update of the cryogenic risk analysis following the 19 September 2
 008 incident
DTSTART;VALUE=DATE-TIME:20091112T130000Z
DTEND;VALUE=DATE-TIME:20091112T150000Z
DTSTAMP;VALUE=DATE-TIME:20130522T053648Z
UID:indico-event-73392@cern.ch
DESCRIPTION:On 19 September 2008\, during powering tests of the main dipol
 e circuit in sector 3-4 of the LHC\, an electrical fault occurred producin
 g an electrical arc and resulting in mechanical and electrical damage\, re
 lease of helium from the magnet cold mass to the insulation vacuum enclosu
 re and consequently to the tunnel\, via the spring-loaded relief discs on 
 the vacuum enclosure. The helium discharge from the cold mass to the vacuu
 m enclosure exceeded by an order of magnitude\, the maximum credible incid
 ent (MCI) flow described in the preliminary risk analysis performed in 199
 8. Basing on the experience gained from the 19 September incident\, a new 
 MCI has been formulated and the cryogenic risk analysis has been revised a
 nd updated. The performed simulations enabled the revision of the helium d
 ischarge system protecting the vacuum enclosure against the over-pressuriz
 ation. \nDuring the incident the amount of about 6 ton of helium has been 
 released into the LHC tunnel in the way that can be classified as a physic
 al phenomenon with a high rate volume production. The performed analysis h
 as shown that any shock phenomena can be excluded\, and the pressure distr
 ibution has been uniform along the tunnel during the discharge process. Th
 e recommendations concerning the mechanical properties of the doors instal
 led in the tunnel have been formulated.\n\nhttp://indico.cern.ch/conferenc
 eDisplay.py?confId=73392
LOCATION:CERN Main Auditorium
URL:http://indico.cern.ch/conferenceDisplay.py?confId=73392
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