CASE STUDY ON BHOPAL TRAGEDY

1. 2.3a The BHOPAL Incident
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India, 2 Dec 84
• Presented to ES-317y at UWO in 1999.
• Dick Hawrelak

2. UC Block Diagram
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3. 3
The Catastrophe
• 54,000 lbs of extremely toxic methyl
isocyanate (MIC) were released from an
elevated stack for a period of nearly two
hours.
• The gas cloud covered an area 2.5 km. wide
by 4.5 km. long over a densely populated
area exposing 200,000 of the 800,000
people of Bhopal.

4. 4
BHOPAL Map

5. 5
Consequences
• 2,000 fatalities were reported initially.
• 15 years later, the death toll has risen to
4,000.
• Some 250,000 people have permanent
disabilities.

6. Emergency Response
• 11,500 people were hospitalized on Dec 3.
• 170,000 were treated the first few days.
• 1000 doctors, 200+ nurses, 700 paramedics
responded.
• 5 hospitals and 22 clinics were used.
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7. Storage Area As Designed
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8. Storage Area As Operated
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9. Sequence of Events
• Prior to the incident, there had been a
reduction in operator staff from 12/shift to
4/shift.
• There had also been a reduction in shift
supervisors from 3/shift to 1/shift.
• Because of these reductions, moral was low.
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10. 10
Dec 2, 10:20 PM
• Day shift operator reports pressure in V-610
as normal at 2 psig.
• The normal range of pressure is 2 to 25
psig.
• Tank contains 90,000 lbs of MIC at 75%
full.
• Tank is blocked with small transfer taking
place at 77 deg F.

11. 11
Dec 2, 10:45 PM
• Shift Changes.
• Normally operators discuss problems
experienced during their shift.
• No problems were communicated to the
midnight shift.

12. 12
Dec 2, 11:00 PM
• Control room operator notes pressure in V-
610 has risen to 10 psig.
• There was no concern since this was still in
the normal operating range.
• The rate of pressure rise over the 40 minute
period was not a concern.

13. 13
Dec 3, 00:15 AM
• A field operator reported a MIC in the MIC
process area.
• This was considered to be a normal fugitive
release and no alarms were sounded.

14. 14
Dec 3, 00:16 AM
• CR operator observes V-610 pressure at 30
psig and rising rapidly.
• The CR operator becomes concerned and
confused about the steps that should be
taken.

15. 15
Dec 3, 00:18 AM
• V-610 pressure goes off scale at 55 psig.
• CR operator runs to V-610 tank in the field.
• He hears tank rumbling, PSV screeching
and concrete cover cracking.
• He runs back to CR & turns on the vent gas
scrubber & the reirculating pump.
• The recirculating pump registers no flow.

16. 16
Dec 3, 00:20 AM
• MIC production supervisor notifies Plant
Superintendent that there is a problem in the
storage area.

17. 17
Dec 3, 00:25 AM
• Plant superintendent arrives at CR and notes
much MIC in the atmosphere.
• He spends the next 15 minutes with the CR
operator to learn what action has been
taken.

18. 18
Dec 3, 00:45 AM
• The Derivatives unit shuts-down because of
the high MIC in the atmosphere.
• The phone lines to the CR are all busy.

19. 19
Dec 3, 1:00 AM
• Derivative unit sounds toxic gas alarm.
• Plt Supt & MIC opr verify that MIC is
coming from an elevated stack before the
flare stack. They trace this back to V-610.
• They turn on firewater monitors on VGS
and V-610.
• They note steam coming from the cracked
concrete as they try to cool V-610.

20. Dec 3, 1:00 AM to 2:30 AM
• Sometime during this period of time, the
PSV reseats itself at 40 psig and the release
stops.
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21. Reasons For The Release
• Water entered V-610 at a high enough level
to start a polymerization reaction.
• The tank contents were initially at ambient
temperatures and the runaway progressed
unchecked because there was no cooling on
V-610.
• The heat of reaction boiled the MIC
monomer and 54,000 lbs of MIC was
released.
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22. Dispersion Results
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GAUSSIAN CONSEQUENCE ANALYSIS - A DETERMINISTIC METHOD
Basis: TNO Dispersion Coefficients With Wind Adjusted To 10m
Case = BHOPAL TNO Dispersion Coefficients - No Elevated Release
Flow, G = 3.6935 kgms/sec 29,314 lb/hr
Wind(10m) = 2.86 m/sec 6.40 mph Wind Uncertainty
Wind Correction Factor, p = 0.21 Angle, Ø = 20 °
Wind(2m), U = 2.86 m/sec Stab Class = Neutral - D
Chemical MIC Roughness = Residential, Zo = 1.0m
Mol Wt = 57.1 Wind
Probit Constant, k1 = -5.6420 CPQRA Probits Ø Variation
Probit Constant, k2 = 0.653 CPQRA Probits Evac Width, m = 5,492 W = 2,978
Probit "n" Constant = 1.637 CPQRA Probits Width
Exposure Duration = 100.00 Minutes
Temp = 25.00 °C 298.3 °K
Pressure = 14.70 psia 1 atm 4,092 LC10
Gas Constant = 0.082
7,545
AQPAC Dimensions = 0 (1 = Yes, 0 = TNO Disp'n Coeff'ts) Evac Dist, m LC01

23. Predicted Consequences
Predicted Consequences
Demographics And HSE Escape Probability
P(e1) = Prob Of Escape In C2 = 0.2 Not Used In Near Field because of elevated release.
P(e2) = Prob Of Escape In Zone 3 = 0.8 Default in U.K. = 0.8, In India ??
Population Density 0.0178 people/m2 (200,000 in 2.5 x 4.5 km area)
Probability Of Being Outdoors = 1.0 Assume poor ventilation = 1.0
Total No People Estimated Estimated
Exposure Wtd Avg Exposed Area Distance No People Exposed No People No People
Zone 3 Area Duratn. min. % Fatality Sq. Meters Meters Triang Area Outdoors Killed Wounded
LC100>LC90 Area A2 LC95 100 95.00% 71,608 919 1,273 1,273 242 1,031
LC90>LC50 Area A3 LC70 100 70.00% 225,691 1,940 4,012 4,012 562 3,451
LC50>LC10 Area A4 LC30 100 30.00% 934,954 4,092 16,621 16,621 997 15,624
1,232,252 21,907 21,907 1,801 20,106
Actual Data After 7 days = 2,000 11,500
After 10 Years - 1994 = 4,000 23,000
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24. 24
Lessons Learned
• V-610 refrigeration unit should never have
been shut down to conserve energy. It was
intended to slow a potential polymerization
reaction if one should accidently occur.
• The VGS should never have been put on
stand-by. It was a critical piece of
equipment and should have been available
100% of the time, as intended.

25. Lessons Learned Cont’d
• The caustic recirculaing pumps on the VGS
should never be turned off. Caustic pumps
often freeze-up when the are not in use and
never respond on demand.
• The plant should not have been in operation
without the flare stack, which was down for
maintenance.
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26. Lessons Learned Cont’d
• The plant never conducted “dry run” or
emergency practice drills.
• The various safety devices were not
checked on a regular basis.
• There was no warning to the nearby
community.
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27. Lessons Learned Cont’d
• There was no communication to local
authorities regarding the hazards of the
plant.
• There was no local emergency plan in
place.
• The shack community was too close to the
plant site. 6,000 to 7,000 meters was
estimated to be a safe distance.
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28. Lessons Learned Cont’d
• When you go through cost cutting measures
to save energy and reduce operators to save
operating expenses, moral is bound to
suffer. In this state, the safety integrity of
the plant is often compromised. This
situation often leads to sabotage or extreme
actions by those losing their jobs.
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29. The Bhopal Aftermath
• Industry throughout the world responded to
the Bhopal Aftermath by adopting the
Responsible Care program.
• 19 resolutions were adopted based on the
lessons learned.
• Emergency planning and green belt
separation are required for all toxic
chemicals.
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30. Possible Exam Questions
• What three critical equipment items were
out of service at the time of the Bhopal
incident?
• What was the global response to the Bhopal
Incident?
• ***
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