Electrical Explosion
Luck is NOT a Robust Barrier

Fault
Occu
rred H
ere
Simplified Schematic of Plant Electric System

t
Faul

ere
red H
r
Occu
FT 1.0
Production
Decrease
0955-1920

Plant Trip
0955

See
FT 2.0

Full Production
1920

No
Personnel
Injury

See
FT 4.0

...
FT 2.0
Plant Trip
0955

Defect in
Cubicle

Causes
are
unknown

END

Contactors
Closed

Defect in
Cubicle
Not
Known
See
FT ...
FT 2.1
Defect in
Cubicle Not Known

Inspections not
capable

END

No test
available

Instrumentation
not capable

END

END
FT 3.0
No 4160volt
Blackout

Fast Transfer
to Start-up
Transformer

Start-up
Transformer
Available

Fault on 4160 V
Bus Cl...
FT 3.1
Fast Transfer to Startup Transformer
(Likely Scenario)

Aux Xfmr
Main Breaker
Opens on
Undervoltage

4160 Fault
Dra...
FT 4.0
No
Personnel
Injury

Stand-off
Distance
of 22’

END

Partial
Shielding
by Cubicle
Stack

Fault on 4160 V
Bus Cleare...
The next slide is a Factorsconsequence Matrix
It shows how various factors
would have affected the
consequences of the eve...
Actual
Case

Case 1 IP
enabled

Case 2
Anomaly
detected

Case 3
Atomizer
not
started.

Case 4
Combustible
s present.

Case...
Eight Questions For Insight

Quality & Safety Impact

What were the event consequences?
What was the event significance?

...
1. Consequences

No personnel injuries. Explosion, fire, trip, lost
revenue, etc.

2. Significance

Saved by luck, lots of...
Now is the time for
•
•
•
•

Questions?
Comments?
Recommendations?
Discussion?
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E atomizer explosion 2013.10.26

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E atomizer explosion 2013.10.26

  1. 1. Electrical Explosion
  2. 2. Luck is NOT a Robust Barrier Fault Occu rred H ere
  3. 3. Simplified Schematic of Plant Electric System t Faul ere red H r Occu
  4. 4. FT 1.0 Production Decrease 0955-1920 Plant Trip 0955 See FT 2.0 Full Production 1920 No Personnel Injury See FT 4.0 No 4160-volt Blackout See FT 3.0 No Rupture Disc Blow Proper Operator Action Spares Including “Breaker” in Stock Operator Initiative END END END
  5. 5. FT 2.0 Plant Trip 0955 Defect in Cubicle Causes are unknown END Contactors Closed Defect in Cubicle Not Known See FT 2.1 4160 Volts on Cubicle CRO Starts Atomizer END END
  6. 6. FT 2.1 Defect in Cubicle Not Known Inspections not capable END No test available Instrumentation not capable END END
  7. 7. FT 3.0 No 4160volt Blackout Fast Transfer to Start-up Transformer Start-up Transformer Available Fault on 4160 V Bus Cleared Feeder Bkr Tripped See FT 3.1 END END
  8. 8. FT 3.1 Fast Transfer to Startup Transformer (Likely Scenario) Aux Xfmr Main Breaker Opens on Undervoltage 4160 Fault Drags Voltage down Aux Xfmr Does Not Open on Overcurrent 4160-volt Feeder Breaker Clears Fault Breaker Opens on Timed Overcurrent Before SUT Main Bkr Shuts Unknown Unknown
  9. 9. FT 4.0 No Personnel Injury Stand-off Distance of 22’ END Partial Shielding by Cubicle Stack Fault on 4160 V Bus Cleared to Limit Energy END END
  10. 10. The next slide is a Factorsconsequence Matrix It shows how various factors would have affected the consequences of the event.
  11. 11. Actual Case Case 1 IP enabled Case 2 Anomaly detected Case 3 Atomizer not started. Case 4 Combustible s present. Case 5 Operator near cubicle. Case 6 No fast transfer Case 7 No circ water pump start Instantaneous protection disabled Yes No (not disabled) Yes Yes Yes Yes Yes Yes Undetected bkr abnormality Yes Yes No Yes Yes Yes Yes Yes Atomizer started Yes Yes Yes No Yes Yes Yes Yes No combustibles nearby Yes Yes Yes Yes No Yes Yes Yes Operator protected by location Yes Yes Yes Yes Yes No Yes Yes Fast transfer Yes Yes Yes Yes Yes Yes No Yes Circ water pump restarted Yes Yes Yes Yes Yes Yes Yes No None Less severe explosion . None. Anomaly fixed. None right away. Latent problem. Worse fire. Potential burns. Severe injury or death. No change. No change. Explosion ,Trip, Lost Revenue, Equipmen t damage No plant trip. Only feeder bkr trip. None None right away. Latent problem. Worse fire, etc.. Explosion, Trip, Lost Revenue, Long outage for investigatio n Explosion,Trip, Lost Revenue, Equipment damage. 4160v blackout. Longer outage due to rupture disc(s) blown. Factors Consequences Personnel Plant/Financial
  12. 12. Eight Questions For Insight Quality & Safety Impact What were the event consequences? What was the event significance? Vulnerability Consummation Exacerbation Mitigation Corrective Action (closeout) What set us up for the event? What triggered the event? What made the event as bad as it was? What kept it from being a lot worse? Learning: What should be learned from the event? Doing: What should be done about it? © 2000, William R. Corcoran, NSRC Corp., 860-285-8779, firebird.one@alum.mit.edu
  13. 13. 1. Consequences No personnel injuries. Explosion, fire, trip, lost revenue, etc. 2. Significance Saved by luck, lots of surprises, Arc Flash hazard underestimated, complex event 3. Set-up Bechtel wiring anomaly, latent defect in “breaker” 4. Trigger Starting an atomizer from Control Room 5. Exacerbation Feeder breaker didn’t trip on instantaneous. This caused plant trip. (what made it worse) kept it from being even worse) Operator location! Fast transfer malfunctioned in our favor! Good personnel actions. Spares on hand. 7. Lessons to be Learned Energizing a circuit is a hazard. Distance and shielding work. Control combustibles. 8. Corrective Actions Stand-off from energizations. Ring out protective circuits. Re-do Arc Flash Study. Re-do breaker coordination. 6. Mitigation (what
  14. 14. Now is the time for • • • • Questions? Comments? Recommendations? Discussion?

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