Take 5 for Safety
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Transcript of Take 5 for Safety
Electrical Fire in Terminal Room
Collider-Accelerator Department12-21-2010
Take 5 for SafetyTake 5 for Safety
Electrical Fire in Terminal Room
On November 9, 2010, in building 911, an electrical fire in a utility room containing stacks of electromagnetic relays near MCR
Activated the fire alarm system and a Halon fire suppression system About 50 relays and associated wiring were damaged by fire; relays
and wiring were associated with the AGS access controls system (ACS) A safe configuration of the AGS ACS was developed and is in place for
the FY11 running period, and the configuration includes features that reduce the risk of fire
There were no personnel injuries The investigation revealed an ignition source was proximate to rapidly
burning materials
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Fire Damage to 1950s First Floor Terminal Room, November 2010 The root cause of this fire was the failure to
identify the presence of non-flame retardant insulation on wiring proximate to CR120 relays that were known to overheat
Multi-conductor wiring installed in the 1950s had an outer sheath that was not flame retardant and inner insulation on individual wires that was found to be flammable in recent tests
Several circuit breakers (CB) powering relays tripped open preventing further damage; one breaker (CB19) did not trip although it should have
The 1978 recall of CR120 flammable contact-arm retainer was not known to Department employees
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Fire Damage to 1970s Second Floor Terminal Room in 2001
The root cause of the 2001 fire was the failure to identify the presence of non-flame retardant covers proximate to CR120 relays that were known to overheat
Plexiglas covers were installed for electrical safety
No significant damage from this fire Records show about 30 relay coils
overheated between 1990 and 2010
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Main Causal Factors Surveillance and Inspection of Relays LTA
· After the 2001 fire, the thermal scanning practice adopted for relay temperature monitoring was inadequate, inconsistent and poorly documented
Tracking and Trending of Low Level Issues from Critiques LTA· The written guidance for Critiques is in a C-AD procedure and it does not require trending of
specific problems or problem classifications over many years
Inaccurate Risk Perception· Managers, engineers and workers accepted relay-coil overheating failures and this was a latent
organization weakness· Coil overheating failures are failsafe for radiation safety but they created an ignition source· Past overheating failures did not result in personnel injury, programmatic loss or in wiring fires
Recognition of Non-Flame Retardant Insulation on Wiring Was Inadequate· Obvious flammables such as Plexiglas covers were the focus of the flammable hazards
reviews for Terminal Rooms, not the adjacent wiring that had insulation dating back to the 1950s
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Was He Supervising or Did He Just Stop By To Ask Directions?
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