© 1999 lockheed martin energy research corporation ca57 what is an accident

© 1999 Lockheed Martin Energy Research Corporation CA57

WHAT IS AN ACCIDENT

WHAT IS AN ACCIDENT

© 1999 Lockheed Martin Energy Research Corporation

OBJECTIVE

CA58

• Identify types of potential chemical accidents and associated hazards


• Can be defined in several ways– an unplanned release of chemical warfare agent into

environment at levels which exceed those permitted by state or federal regulations

– more conservative definition is any unplanned event that could lead to the release of chemical warfare agent

AN ACCIDENT . . .


• Important to know amount of material accidentally released

• Amount of material released called “source term”• Source term and weather conditions at time of release

determine– how far downwind hazardous materials will travel

– concentration of chemical warfare agent to which people could be exposed

CA60

SIZE OF ACCIDENT


PROXIMITY TO POTENTIAL

ACCIDENT SITE

• Also important to know how close people might be to a potential accident site and their location with respect to airborne agent plume

Illustrated CSEPP installation and community


ACCIDENT LIKELIHOOD

• Most likely accidents are small ones that do not pose a threat except to someone in very close proximity to accident

• Large accidents (source terms large enough to pose a threat to community) have much lower probability of occurring

• Unlikely that an accident will cause injury or death to anyone


• Engineers and scientists systematically studied different ways accidents could occur and estimated how likely events were that caused an accident

• They estimated probabilities of many different accidents and calculated number of fatalities that could occur for each accident

• They calculated the consequences of each accident

Risk =Probability For

of X Consequences ∑ all Accident (Times) (Summed) Events

CA63

WHAT IS MEANT BY UNLIKELY?

Calculation of risk


POTENTIAL ACCIDENT TYPES

AND HAZARDS• If accident large enough to pose threat to public,

dominant hazard is from breathing air in which agent exists as vapor

• Paths for liquid chemical warfare agent to travel from accident to off-site are limited and relatively easy to block therefore people off-site unlikely to encounter liquid agent


THREE BASIC TYPESOF POTENTIAL

ACCIDENTS

1. Spill

2. Explosion

3. Fire


SPILL

(not to scale)

• Onto ground or other surfaces• Resulting puddle of agent (liquid deposition) can

evaporate into vapor and drift downwind

Example of a plume resulting from a spill


(not to scale)

EXPLOSION

• Causes droplets of agent to be formed• Larger, heavier droplets quickly fall to ground

(deposition)• Releases vapors and aerosols (smaller droplets and

particles) that can travel greater distances

Example of a plume resulting from an explosion


FIRE

(not to scale)

• Both aerosols and vapors are formed• Vapors and aerosols lifted higher into air because of

heat from fire• Hazard similar to those of an explosion

Example of a plume resulting from a fire


DIFFERENCE BETWEENAEROSOLS AND

VAPORS• Think of a chemical agent release

in terms of hair spray coming from a spray can:– when spray is release, it is an aerosol

– larger particles and/or droplets are deposited near point of release

– particles quickly fall out of air onto hair and skin

– person across room can smell hair spray from breathing vapors released


• It is very unlikely the public would be exposed to droplets and aerosols

• Particles will mostly fall out of plume (via deposition) by time plume reaches installation boundary

WHAT IF AN ACCIDENT OCCURS?


VAPOR HAZARD

• For most accidents, the primary health hazard comes from vapors when they are breathed in or come in contact with skin or eyes

• Agent vapors pose greatest hazard when inhaled because they are rapidly absorbed by lung tissues

• Lethal dosage for agent vapor breathed in is several times lower than lethal dosage for vapor contact with skin


ACCIDENT CATEGORIES

• Selection of protective action strategies contingent on characteristics of accident

• Accident categories are group of accident scenarios bound together by common source terms and meteorological conditions

• Designed to support grouping of large number of protective action strategies

• Each installation has set of accident categories

CA72


CHEMICAL EVENT EMERGENCY

NOTIFICATION SYSTEM• Standard chemical accident notification• Provides a common language between installation and

off-site emergency responders• Fosters clear understanding and ready reference for

emergency response actions• Off-site response consists of 4 levels

– nonsurety (does not involve chemical warfare agents)

– limited area, post-only, and community emergencies (involve chemical warfare agents)

CA73


NON-SURETY EMERGENCY

• General interest to public• Poses no chemical surety hazard• Action: Notification to IRZ designated points of

contact

CA74


Army Installation Boundary

Limited Area Boundary



Plume



LIMITED AREA EMERGENCY

• Declared when predicted chemical agent no-effects dosage does not extend beyond chemical limited area

• Action: Notification of IRZ and State points-of-contact– IRZ emergency response

officials may go to level of readiness


POST-ONLY EMERGENCY

CA76

• Declared when predicted chemical agent no-effects dosage extends beyond chemical limited boundary but not installation boundary

• Not expected to present danger to off-site public• Action: Notification of IRZ, PAZ,

and State-designated points-of-contact– IRZ response organizations

mobilize– precautionary protective

actions may be initiated in nearby areas


Plume




COMMUNITY EMERGENCY

• Declared when predicted chemical agent no-effects dosage extends beyond installation boundary

• Action: Notification of IRZ, PAZ, and State-designated points-of-contact– all emergency response

organizations mobilize

– IRZ and affected PAZ areasimplement specified protective actions

CA77


Plume




• Army’s detection capability consists of low-level and gross-level detectors

• Any vapor detection efforts off-site would be conducted by Army survey teams using appropriate equipment

CA78

CHEMICAL WARFARE

AGENT DETECTION

© 1999 lockheed martin energy research corporation ca57 what is an accident

Documents

accident risk

liquid agent slide

spill slide

potential accident site

community slide

liquid chemical warfare

calculation of risk

airborne agent plume