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

2

3

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

4

5

6

7

8

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

9

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

10

Was He Supervising or Did He Just Stop By To Ask Directions?

11