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2.3a The BHOPAL Incident India, 2 Dec 84

• Presented to ES-317y at UWO in 1999.

• Dick Hawrelak

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UC Block Diagram

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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.

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BHOPAL Map

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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.

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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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Storage Area As Designed

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Storage Area As Operated

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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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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.

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Dec 2, 10:45 PM

• Shift Changes.

• Normally operators discuss problems experienced during their shift.

• No problems were communicated to the midnight shift.

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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.

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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.

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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.

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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.

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Dec 3, 00:20 AM

• MIC production supervisor notifies Plant Superintendent that there is a problem in the storage area.

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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.

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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.

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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.

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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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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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Dispersion Results 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

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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 EstimatedExposure 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 WoundedLC100>LC90 Area A2 LC95 100 95.00% 71,608 919 1,273 1,273 242 1,031LC90>LC50 Area A3 LC70 100 70.00% 225,691 1,940 4,012 4,012 562 3,451LC50>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 11,500After 10 Years - 1994 = 4,000 23,000

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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.

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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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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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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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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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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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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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