Imagine that a hydroelectric dam burst or a large amount of radioactivity was accidentally released from a nuclear power plant? Suppose that a plume of toxic, flammable gases was released from an oil refinery fire or a gas pipeline explosion? Where would people living near the site of any of these incidents go, and how fast could they leave? If a terrorist group threatened to detonate a weapon of mass destruction in the center of a city, would it be feasible to evacuate the population at risk before the onset of damage (that could also affect the energy infrastructure)? Answers to these questions are being sought by ORNL researchers.
EVACUATION PLANNING TOOL
An ORNL-developed computer tool called the Oak Ridge Evacuation Modeling System (OREMS) is being used to help emergency responders develop plans for moving people quickly and safely away from the site of most any disastrous event. Various scenarios can be tried using this state-of-the-art, evacuation-planning model to determine which evacuation strategies would likely work best. These scenarios can range from a natural event, such as an earthquake or hurricane, to a deliberate attack on part of our energy infrastructure, to an accidental release of hazardous materials.
“The 1984 accident in Bhopal, India, that killed at least 5000 persons sparked interest in the problems of hazardous materials releases in populated areas,” says John Sorensen of ORNL’s Environmental Sciences Division (ESD). “The Three Mile Island accident in 1979 dramatically increased public awareness of the need for emergency planning for nuclear power plants.”
OREMS was developed by a team led by Sorensen. He and his colleagues have conducted research to assess community preparedness for dealing with an industrial accident that resulted in the release of toxic chemical plumes or radiation.
OREMS is based on data obtained from actual experiences and events, such as dam failures in Colorado and Wyoming and explosions at chemical plants. OREMS can be used to estimate clearance times for evacuating an area, predict traffic bottlenecks, and evaluate traffic control strategies.
“Evacuation planning has become very important for utilities that operate nuclear power plants,” says Sorensen, noting that OREMS is being used for four such facilities. “The Nuclear Regulatory Commission (NRC) requires that utilities use 2000 census data to estimate the time needed to evacuate the population around all nuclear power plants in case of a natural, accidental, or deliberate threat. Also, each nuclear utility must provide evacuation estimates as part of its application to renew its license to operate a nuclear power plant after its current license expires.”
Sorensen and his colleagues can offer experience and expertise in this area. For nuclear power plants, these ORNL researchers have studied evacuation planning issues, as well as the adequacy of warning systems, emergency plans, and public information programs. This work has been funded by DOE, NRC, the Federal Emergency Management Agency (FEMA), and the Three Mile Island Public Health Fund.
OREMS is also being used by planners in Las Vegas, Nevada, to evaluate evacuation scenarios there. A city department in Florida has requested it to use in making evacuation plans in the event of a hurricane.
“We have added a user interface to make it easier for a lay person to operate the OREMS model,” Sorensen says. “We expect this ease of use will increase demand for our tool.”
OREMS models the flow of vehicles over a network of roads around a source of hazardous material, as could result from an accident at a plant in which a plume of toxic chemicals is released. Most road network data are available from local departments of transportation, and local population census data are available from the U.S. Census Bureau.
Sorensen has a colleague in Florida who for a number of years has studied the evacuation of people after they were warned about an approaching hurricane. His studies show that the occupancy count for cars during evacuations consistently averages 3 to 3.2 people per vehicle.
“So if you know the population in the area of the disaster,” Sorensen says “you can estimate the approximate number of vehicles that will be on the network of roads. Using traffic-loading curves to calculate the distribution of cars over time, you can predict how long it will take for the local population to evacuate the area.”
The OREMS tool can be used to predict how fast a town can be evacuated if lanes are reversedfor example, turning a two-way, two-lane road into a one-way, two-lane road. For example, OREMS was used to illustrate the best way to evacuate a small town in Kentucky that can be accessed only by a two-lane road.
“We found that the town could be evacuated in less than three hours by reversing one lane and making the whole road one way,” Sorensen says. “It would take a lot longer if the road remained a two-way street.”
Use of OREMS might have prevented the congestion that resulted when people drove away from Florida and South Carolina in an attempt to escape Hurricane Floyd in 1999. “Part of the highway was made into a four-lane, one-way road to speed the evacuation,” says Sorensen. “But when the four lanes were merged into two lanes, terrible traffic congestion and delays resultedmore of a problem may have been created than would have happened with better planning.”
OREMS is the only evacuation simulation model that uses state-of-the-art traffic simulation codes derived from U.S. Department of Transportation (DOT) models. Furthermore, it is the only model of its kind endorsed for use by DOT in regional evacuation planning. OREMS was developed to replace obsolete technology used in other evacuation simulation approaches.
EVACUATION vs SHELTER IN PLACE
How do people normally respond to an emergency involving a release of hazardous material? Sorensen and his wife Barbara Muller Vogt (also of ESD) studied the responses of people to an actual accidentthe explosion of a pesticide repackaging plant that occurred May 8, 1997, in West Helena, Arkansas. In this accident, clouds of foul-smelling smoke spewed from the plant. “We found that 90% of those who were told to evacuate did so, but only 27% of those told to shelter in place stayed in their buildings,” Sorensen says. “At least 68% of those people advised to shelter chose to evacuate instead.”
Evacuation is not always wise. You could leave your house and unknowingly move closer to a plume of hazardous material rather than away from it. If the air initially is more contaminated outside your home than inside, studies by Sorensen and Vogt suggest it would be better to stay in an interior room and cover the doorway with duct tape and plastic sheetingnot a wet towelto prevent contaminated air from infiltrating the “safe” room. “You are 10 times safer if the doorway is sealed with these materials than if it is not,” says Sorensen. He recommends also that you take a battery-operated radio with you into the interior room to find out when it is safe to re-enter the area outside the room. After a few hours, the concentrations of the hazardous vapor infiltrating buildings may exceed those of the airborne toxic materials outside. Then it would be smart to leave your house until experts agree that it is safe to live there again.
This advice also applies to a plume of biological or chemical warfare agents. Sorensen made a video showing how people can protect themselves from these weapons of mass destruction for FEMA, from which he gets most of his funding. (The rest comes from the Department of Energy.) The video, available on tape and digital video disk (DVD), is called “Residential Shelter in Place.” One of the points made in the video is that people who shelter in place have more protection against toxic airborne agents if their homes have been weatherized to reduce energy use.
The results of Sorensen’s studies of people’s responses to emergencies were borne out by the reactions of occupants of the World Trade Center’s twin towers in New York City after they were hit by hijacked airplanes in the terrorist attack of September 11, 2001. “We found no evidence of panic,” Sorensen says. “Most people evacuated the twin towers and ignored the announcement after the first tower was hit telling them to stay in their offices. We found evidence of people helping people, an emerging therapeutic community. For example, two men carried out a woman who was wheelchair-bound.”
One thing that has changed in recent years is the speed of communication in response to an emergency, thanks to cell phones, electronic mail, and informative Web sites on the Internet. Sorensen’s study of the evacuation following the eruption of the Mt. St. Helens volcano in 1980 showed that it took 4 to 8 hours for people in eastern Washington to learn they could be covered in volcanic ash if they didn’t leave the area.
In the case of the fourth hijacked airplane that crashed near Shanksville, Pennsylvania, on September 11, communication by cell phone made some passengers aware that the hijackers of their airplane were on a suicidal mission to crash into an important American building filled with people. As a result, some of the passengers organized a response and took action to wrest control of the plane away from the terrorists. Their response to the perceived danger, says Sorensen, shows an “unprecedented speed of adaptation to the situation.”
HAZARD WARNING SYSTEM
In his “Hazard Warning Systems: Review of 20 Years of Progress,” published in the May 2000 issue of Natural Hazards Review, Sorensen writes that the United States has no comprehensive national warning strategy that covers all hazards in all places. “Since 1975,” says Sorensen, “forecasts for floods, hurricanes, and volcanic eruptions have improved most significantly, with public dissemination of warnings improved the most for hurricanes. However, a 100%-reliable warning system does not exist for any hazard.”
He also lists the myths about public responses to warnings about impending disasters: The public will panic. People will become overwhelmed with too much information. People won’t respond if false alarms have been issued earlier. Emergency information should come from a single spokesperson. People will take action and follow instructions immediately after a warning. None of these beliefs are true, Sorensen says.
Sorensen (as chair of the Subgroup on Prediction, Forecast, and Warning) and Vogt both contributed to the recently published book, Disasters by Design, edited by Dennis Mileti. Sorensen wrote about warning systems and Vogt wrote about the vulnerability of physically challenged people to emergencies and disasters and the need to identify which people need assistance and how to ensure that they get help.
Sorensen’s expertise in the area of planned and actual responses to natural and accidental disasters has been sought recently by the news media and the National Academy of Sciences because of the September 11 terrorist attacks. There is a need to determine how to plan effective responses (e.g., rapid evacuations, clear communication about sheltering in place, and the best ways to perform personal decontamination) to intentionally created disasters, in order to save lives and prevent injuries as much as possible.
DISRUPTION OF OIL AND GAS PIPELINES
If an oil or gas pipeline or distribution facility were blown up by a terrorist attack, how long would it take to restore service?
This question was studied in the mid-1980s by Sorensen and his ORNL colleagues L. W. Rickert, J. H. Horton, and W. Reed, in collaboration with M. M. Stephens at Tulane University. They published a report entitled “Emergency Response to Saboteur-induced Damage to Oil and Gas Distribution Facilities.”
For this report, they presented engineering calculations for many scenarios, including blowing up a pipeline running across a river and blowing up a terminal for offloading oil from a ship to a pipeline.
“We found that for the damage scenarios considered, most systems could be jury-rigged into at least partial operating capacity within a short time,” Sorensen says. “Depending on the situation, permanent replacement of pumping or compressor stations would take from 12 to 18 months because of the time it takes to deliver and install large valves, compressor drivers, and pumps. The federal government could help the pipe-line industry by working with it to develop emergency response plans to guide it in jury-rigging repairs, to minimize disruptions in service.”
So far, the U.S. government has not followed this recommendation, but there may be growing interest in doing so now that the U.S. Office of Homeland Security exists.
EMERGENCY PLANS FOR CHEMICAL FACILITIES
Sorensen and his associates have assessed community preparedness for dealing with chemical accidents. They have identified the technology, procedures, and management practices used to alert the public to a chemical release. They have investigated people’s responses to chemical accidents to protect themselves, including such strategies as evacuating, sheltering in place, and decontaminating victims and affected areas.
Sorensen and his colleagues have also provided technical support for the planning, training, and reentry programs associated with the disposal of the nation’s stockpile of chemical weapons. The final programmatic environmental impact statement for the disposal program, which involves on-site incineration of the chemical weapons near eight different cities, recommended a community-based emergency preparedness program. ORNL has been providing technical support to the Chemical Stockpile Emergency Preparedness Program, jointly managed by the U.S. Army and FEMA, which has the ambitious goal of achieving state-of-the-art plans with maximum public protection.
Largely as a result of the diversity of emergency management research at the Laboratory, ORNL was identified by DOE as a lead laboratory for emergency management at a recent Energy Infrastructure Assurance Technology Exposition, held in Washington, D.C. Some future ORNL research may be focused on developing plans to better prepare communities to deal with terrorist attacks involving weapons of mass destructionattacks that could have an adverse effect on not only populations but also energy infrastructure.
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