Lawrence Livermore National Laboratory



Since its foundation as an operational center in 1979, NARAC has responded to hundreds of alerts, accidents, and disasters; supported thousands of exercises; and conducted numerous studies. As part of its emergency response mission, NARAC collaborates with and supports a wide range of organizations, including over several hundred federal, state, and local agencies, emergency response teams, operations centers, and international organizations.

Color key: Accidents / Disasters Prepardness Exercises Operational Milestones

Choose a decade: 1970s, 1980s, 1990s, 2000s, 2010s


During the 2010s


2014 - Waste Isolation Pilot Plant
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NARAC was activated by DOE in response to a February 14-20 release of transuranic radioactive material at the Waste Isolation Pilot Plant (WIPP) in New Mexico. Airborne radioactive material was detected by the plant's stack exhaust and environmental air monitoring systems from an underground release. NARAC plume model simulations based on detailed on-site meteorological data and WIPP-developed airborne radioactivity release estimates were used to estimate on and off-site dose and contamination levels and were included in information provided to the public.

2011 - Mars Science Laboratory Spacecraft Launch (Florida)
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National Aeronautics and Space Administration (NASA) and other federal emergency response managers assembled at the Kennedy Space Center (KSC) to be ready to respond in the unlikely event of a launch accident involving the Mars Science Laboratory plutonium-238 radioisotope thermal generator.

A LLNL staff member served as the DOE Senior Science Advisor for the launch. Under his guidance, NASA deployed 30 Environmental Continuous Air Monitors which transmitted real-time alpha-radiation data from KSC and the surrounding communities.

NARAC's operations center provided worst case analyses of potential accident scenarios to over 70 local, state, and federal emergency responders and decision makers. The successful launch occurred on November 26, 2011 at 10:02am EST.

2011 - International Atomic Energy Agency Support
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Under the auspices of the Department of Energy Office of International Emergency Management and Cooperation, NARAC supports the International Atomic Energy Agency (IAEA) and its member states by providing the International eXchange Program (IXP) system for sharing information and performing radiological release simulations. In 2011, the IAEA Atomic Energy Agency Atoms for Peace recognized NARAC's contributions with a citation stating: "The Incident and Emergency Centre is pleased to welcome the participation of the International Exchange Program, National Atmospheric Release Advisory Center [LLNL/DOE] in the Response Assistance Network (RANET), thereby helping to strengthen the global system for the provision of international assistance in a nuclear or radiological emergency."

2010 - Deepwater Horizon Oil Spill (Gulf of Mexico)
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At the request of the federal Scientific Support Coordinator for the Deepwater Horizon incident, IMAAC Operations at LLNL produced 24-hour forecast of the smoke concentrations that could be produced by planned oil slick burns in April-May, 2010.

These simulations showed that air quality impacts from small in-situ burns would be unlikely to affect operations farther than a few km downwind and were provided to the National Oceanic and Atmospheric Administration and the Environmental Protection Agency.

IMAAC/NARAC also provided a simulation of the original fire on the Deepwater Horizon oil platform on April 22, 2010 at the request of the Department of Homeland Security.

2012 - NARAC Dedicated Compute Cluster
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NARAC acquired a 336-processor computer cluster to improve computational performance for complex, long running simulations such as those needed during the response to the Fukushima Dai-ichi Nuclear Power Plant accident. The cluster was interfaced with the NARAC modeling system and modifications were made to key models and software reducing the run-time required for complex or long-duration simulations by a factor of 25.

2011 - Las Conchas Wildfire (New Mexico)
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NARAC was activated on June 26, 2011 by the Department of Energy (DOE) to respond to the Las Conchas wildfire in New Mexico which posed a potential threat to Los Alamos National Laboratory (LANL).

NARAC provided twice-daily high-resolution regional wind forecasts to LANL, DOE, the Environmental Protection Agency and the U.S. Fire Service. The weather forecasts also were used on an experimental basis to generate a smoke visibility warning for the Fire Service.

NARAC prepared radiological source terms and worked with DOE to coordinate the shipment of portable real-time radiological monitors with NARAC satellite data feeds in case the fire reached Los Alamos (fortunately neither were needed as the fire did not penetrate the LANL site).

2011 - Fukushima Dai-ichi Nuclear Power Plant Emergency (Japan)
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NARAC was activated on March 11, 2011 following the devastating earthquake and tsunami that damaged the Fukushima Dai-ichi Nuclear Power Plant. NARAC operated on a 24/7 basis for almost 4 weeks and remained on alert through the end of May providing:

  • Daily weather forecasts and atmospheric transport predictions to inform planning for field monitoring operations and provide situational analysis for deployed U.S. personnel
  • Estimates of possible dose in Japan based on hypothetical U.S. Nuclear Regulatory Commission radionuclide release scenarios to support protective action planning for U.S. citizens in Japan
  • Predictions of possible plume arrival times and possible dose levels at locations in the U.S.
  • Source estimation and plume model refinement based on atmospheric dispersion modeling and available monitoring data
2010 - Eyjafjallajökull Volcano Eruption (Iceland)
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NARAC conducted demonstration predictions of the local dispersion of volcanic ash from the Eyjafjallajökull volcano that erupted in April, 2010. These simulations were provided to the Iceland Civil Defence Authorities and Meteorological Office under the auspices of the Department of Energy.

The simulations included a 144-hour forecast of the evolving spatial distribution of local, near-ground-level airborne and deposited ash concentrations using information provided by Icelandic government agencies on measured ash particle sizes.

NARAC products were transmitted to Iceland using the International Exchange Program (IXP) system.

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During the 2000s


2009 - Empire 09 exercise (Albany, NY)
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NARAC participated in the DOE-led Empire 09 exercise, which involved 550 participants from 30 federal, state, and local agencies. The challenging exercise scenario involved two dirty bombs using different radiological materials.

New Radiological Dispersal Device Briefing Products were produced for presentations to decision makers and the new LLNL CMweb was used to distribute NARAC and Federal Radiological Monitoring and Assessment Center (FRMAC) plots.

2008 - ConvEx-3 International Exercise, Mexico
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The International Atomic Energy Agency (IAEA) holds the Convention Exercise every 3–5 years. NARAC supported the 2008 exercise under the auspices of the Department of Energy. Mexico used LLNL’s IXP Web system to send radiological event notification to the U.S. and to share source-term and weather data with NARAC. LLNL provided predictions of the potential radiological contamination and health effects from the hypothetical nuclear power plant venting scenario.

2008 - Kilauea Volcano venting (Volcanoes National Park, HI)
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IMAAC/NARAC Operations predicted the health threat due to unusually large ventings of sulfur dioxide from the Kilauea crater in Hawaii Volcanoes National Park.

IMAAC/NARAC provided high-resolution forecasts and worked with the Department of Homeland Security (DHS), the Environmental Protection Agency (EPA), the Defense Threat Reduction Agency (DTRA), National Oceanic and Atmospheric Administration (NOAA), Civil Support Teams (CSTs), the National Park Service, the U.S. Geological Survey (USGS), and both the State and County of Hawaii.

The National Park Service closed the park and the County of Hawaii evacuated the town of Volcano for several days.

2007 - TOPOFF 4 exercise (Oregon, Arizona, and Guam)
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TOPOFF 4 challenged IMAAC/NARAC to support nearly simultaneous RDD events in three different locations: Portland, Oregon; Phoenix, Arizona; and Guam. The center worked collaboratively with operations centers, field teams, and technical experts to predict blast and radiation impacts and correctly estimate the quantity of source material and explosives used.

IMAAC was cited in the After Action Report for its success in coordinating federal plume modeling and providing model products to the wide-range of agencies involved in the response.

2007 - Solvents tank fire (Valley Center, KS)
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IMAAC/NARAC provided a 12-hour plume forecast for the massive Barton Solvents tank fire in Valley Center, KS. Plume forecasts were used to inform evacuation decisions.

2006 - Hazardous-waste plant fire (Apex, NC)
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IMAAC/NARAC produced forecasts of the downwind impacts from a major fire that burned overnight at a hazardous waste plant in Apex, North Carolina, in support of on-scene state and federal agencies, as well as the DHS National Operations Center in Washington DC. The center also estimated health effects from a chlorine facility potentially at risk due to the fire.

2006 - Pluto New Horizons launch (Kennedy Space Center, FL)
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LLNL deployed automated radiological measurement stations as a new element of DOE/NASA's support during launches of spacecraft powered by Radioisotope Thermoelectric Generators. These measurement stations provide near-real-time data feeds, significantly reducing the time required for NARAC to obtain data to refine model calculations.

2005 - Solvent plant fire (Fort Worth, TX)
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Fire and explosions occurred at a chemical plant in Fort Worth, Texas. IMAAC/NARAC estimated release rates based on chemical inventory information and provided predictions that were used by the City of Fort Worth to develop a shelter-in-place map for the public.

2005 - Chlorine railcar spill (Graniteville, SC)
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On January 6, 2005, two freight trains collided in the town of Graniteville, South Carolina, resulting in the rupture of railcars transporting liquefied chlorine. Approximately 60 tons of chlorine discharged, resulting in nine deaths, 500 injuries, and evacuation of more than 5,000 residents for periods up to nine days.

IMAAC/NARAC Operations supported monitoring teams from the Environmental Protection Agency (EPA) during the week-long clean-up operations following the accident.

2004 - Democratic National Convention (Boston, MA)
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IMAAC/NARAC Operations deployed a staff scientist to Boston to provide plume modeling expertise in support of the Multi-Agency Coordination Center's coverage of the 2004 Democratic National Convention.

2004 - Chemical facility fire (Conyers, GA)
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Only days after Interagency Modeling and Atmospheric Assessment Center (IMAAC) Operations support began at LLNL, a major fire broke out at a chemical facility in Conyers, Georgia. Approximately 250,000 lbs of chlorine compounds burned over a two-day period.

IMAAC/NARAC worked closely with the Department of Homeland Security (DHS), Department of Energy (DOE), Environmental Protection Agency (EPA), National Oceanic and Atmospheric Administration (NOAA), State of Georgia, and other agencies to develop data-informed model predictions that were used to assess the public health risk, guide monitoring teams, and inform sheltering recommendations.

2003 – 2007 - Environmental biological-agent detections
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IMAAC/NARAC analyzed wind patterns and possible source locations following several detections of biological agents by monitoring systems deployed in the US. All airborne agents were found to originate from natural environmental sources.

2003 - Mars Exploration Rover launches (Kennedy Space Center, FL)
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NARAC deployed personnel to Kennedy Space Center and provided daily forecasts of worst-case accident scenarios for the launch of NASA's two nuclear-powered Mars Exploration Rover spacecraft.

2002 - Winter Olympics (Salt Lake City, UT)
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NARAC supported the 2002 Winter Olympics as part of DOE's radiological emergency preparedness efforts.

NARAC developed access to a high-density regional meteorological observation network in the Salt Lake City area. Center staff deployed to the Unified Command Center in Salt Lake City and participated in interagency readiness exercises.

2000 - TOPOFF 1 exercise (Colorado, New Hampshire, and National Capital Region)
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The four congressionally mandated Top Officials (TOPOFF) counterterrorism exercises have been the largest exercises conducted in the US, involving local and state emergency responders and decision makers, federal agencies, and the White House.

For TOPOFF 1, NARAC produced real-time plots for three scenarios: a bioterrorism attack in Denver, CO; a chemical agent release in Portsmouth, NH; and a radiological dispersal device (RDD) in Washington, DC.

2000 - Cerro Grande wildfire (Los Alamos, NM)
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High winds turned a controlled burn in New Mexico into a disastrous forest fire that caused an estimated one billion dollars of damage and destroyed hundreds of homes and buildings.

NARAC developed wind forecasts and estimates of potential radiological hazards when the fire swept through parts of Los Alamos National Laboratory.

2009 - Presidential Inauguration (Washington, D.C.)
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NARAC/IMAAC supports National Security Special Events. For the 2009 and 2013 Inauguration events in Washington, DC, NARAC/IMAAC coordinated plume-modeling support with local, state, and federal agencies under the auspices of DOE and DHS, developing detailed interagency response procedures and deploying a liaison to the Washington DC multi-agency coordination center.

2008 – 2014 - Communication of Plume Hazard Information
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The National/Homeland Security Council tasked the Departments of Energy and Homeland Security to develop versions of NARAC/IMAAC atmospheric plume hazard products for use in briefing senior decision makers, emergency operations centers, and first responders. Versions of these "Briefing Products" have been developed for Radiological Dispersal Devices (RDD), Improvised Nuclear Devices (IND), Nuclear Power Plant (NPP) accidents, and Chemical and Biological (CB) releases. The reception of the new "Briefing Products" has been overwhelmingly positive, with the products praised as a major advance in effectively communicating hazard areas in easily understood terms and providing important information on the actions decision makers need to consider.

2008 - DOE Consequence Management Web site
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LLNL/NARAC was selected by the DOE Office of Emergency Response to develop a unified web site for distribution of all of its Consequence Management products. The CMweb stores and disseminates data, model products, and supporting information for the Federal Radiological Monitoring and Assessment Center (FRMAC), including NARAC model analyses.

2007 - International eXchange Program (IXP) Web
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NARAC supports the DOE/NNSA Office of International Emergency Management and Cooperation (IEMC) in strengthening world-wide emergency preparedness and response capabilities by participating in international cooperative research and serving on international expert committees. In 2007, LLNL developed an International eXchange Program (IXP) Web site that allows the IAEA and member states to run and share plume-model results under DOE auspices.

2007 - Welding facility fire (Dallas, TX)
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IMAAC/NARAC estimated the downwind footprint from explosions and fire at a welding facility south of Dallas, Texas.

2006 - Southern Crossing exercise (Dothan, AL)
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During the Southern Crossing exercise, NARAC worked closely with DOE, state teams, and the Federal Radiological Monitoring and Assessment Center (FRMAC) to develop realistic assessments of the impacts of a hypothetical dirty bomb.

Based on field and aircraft survey data, NARAC and FRMAC estimated the amount of radioactive material in the bomb and projected doses requiring the relocation of the public, as well as areas of potential crop contamination.

2005 - Hurricane Katrina (New Orleans, LA)
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In the wake of Hurricane Katrina, IMAAC/NARAC provided airborne-hazard predictions for several major industrial fires and chemical facilities at risk. The center worked with the National Oceanic and Atmospheric Administration (NOAA) Hazardous Materials Response Division and their deployed personnel in Louisiana.

In the months that followed, IMAAC/NARAC also assisted Environmental Protection Agency's (EPA) scheduling of debris burns by making 24-hour forecasts of the resulting hazardous footprint.

2005 - TOPOFF 3 exercise (New London, CT)
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IMAAC/NARAC provided accurate and timely predictions for TOPOFF 3, one of the nation's most realistic and complex counter-terrorism exercises.

The exercise kicked off with a simulated truck bomb in New London, Connecticut. IMAAC/NARAC analysts rapidly concluded that a small plane was the source of a blister-agent attack and not the bomb. Data provided later in the exercise confirmed the accuracy of this analysis.

Model prediction were used by local, state, and federal agencies, including the White House.

2004 - Chemical warehouse fire (Cincinnati, OH)
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One of the largest fires in Ohio's history broke out at the Queen City Barrel storage facility in Cincinnati, which contained over 50,000 drums of chemicals.

Concerned about potential health effects, the Cincinnati Fire, Health, and Environmental Departments used IMAAC/NARAC predictions to guide approach routes, plan air sampling, and develop shelter-in-place recommendations.

IMAAC/NARAC staff worked with the city to analyze the chemical hazard and provided forecasts of changing wind and plume directions.

2004 - Establishment of IMAAC
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The DHS-led Interagency Modeling and Atmospheric Assessment Center (IMAAC) was created at the direction of the Homeland Security Council in April, 2004. The IMAAC's role is to serve as "the single point for the coordination and dissemination of federal dispersion modeling and hazard prediction products that represent the Federal position" during incidents requiring federal coordination. The IMAAC is supported by eight federal agencies: DHS, DOE, DOD, EPA, HHS NASA, NOAA, NRC. NARAC served as the IMAAC Operations Center from 2004-2012 and is currently the primary provider of radiological/nuclear modeling for the IMAAC under DOE auspices.

2003 - TOPOFF 2 exercise (Seattle, WA)
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TOPOFF 2 was the first national-scale exercise led by the new Department of Homeland Security (DHS).

NARAC had an unprecedented role in the "dirty bomb" scenario in Seattle, supporting DOE's nuclear incident response teams, the interagency Federal Radiological Monitoring and Assessment Center (FRMAC), and first responders under the Local Integration of NARAC with Cities (LINC) Program. NARAC used its new Web portal to distribute plume products.

2003 - Gasoline barge fire (Staten Island, NY)
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A gasoline tanker-barge exploded and caught fire near the southern end of Staten Island. The plume was visible throughout the New York City area, and numerous 911 calls expressed concerns about another terrorist attack.

At New York City's request, NARAC modeled ground-level smoke concentrations, which were used to guide monitoring teams and to inform decisions on how to protect the public.

2001 - Post 9/11 threat assessments
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Over several months following the World Trade Center attack, NARAC provided assessments for a wide range of terrorist threats.

2000 – Present - Third-generation NARAC System

The third-generation Unix-based NARAC central computer system was a complete redesign using modern computer technology and next-generation atmospheric models. The system incorporated global and mesoscale weather forecast models and access to high-resolution weather observation networks.

2000 – 2003 - Local Integration of NARAC with Cities (LINC)
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The Local Integration of NARAC with Cities (LINC) pilot program demonstrated the value of NARAC's advanced operational modeling capabilities to local, regional, and state agencies. NARAC worked closely with five cities — Seattle, New York City, Cincinnati, Fort Worth, and Albuquerque — and their regional partners to develop technologies, interagency procedures, and training to support first responders and emergency operations center staff.

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During the 1990s


1999 – Present - NARAC Web Software
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New Java and Web-based tools were developed and deployed to allow users to access and share NARAC predictions. Interactive features and additional geographical information (street maps, aerial imagery, and population data) were provided for improved situational awareness.

1998 - Tire dump fire (Tracy CA)
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LLNL's Fire Chief requested NARAC assistance when a large tire dump south of Tracy, California, caught fire late on the afternoon of August 7. NARAC provided forecasts of the density of ground-level smoke over the following weekend to inform decisions on actions needed to protect the public. NARAC regularly responds to requests for assistance from the State of California and local communities.

1997 - Cassini launch (Kennedy Space Center, FL)
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Electrical power for the Cassini spacecraft was supplied by three Radioisotope Thermoelectric Generators. NASA requires NARAC support for any launch involving significant quantities of radioactive materials. LLNL personnel deploy to Florida and the center is prepared to respond in case of a launch accident.

1996 February 28 - NARAC Dedication (LLNL, CA)
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A new, specially designed National Atmospheric Release Advisory Center (NARAC) facility was dedicated on February 28, 1996. The building provided an operations center, computer rooms, a uninterruptible power supply and backup power generators, redundant communications systems, training facilities, and staff and program offices.

1995 - Nitric-acid railcar accident (Bogalusa, LA)
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ARAC assisted in the analysis of the potential health effects from a nitric acid railcar release in the rural town of Bogalusa, Louisiana. DOE and the U.S. Air Force authorized a joint federal offer of assistance to the State of Louisiana.

1993 - Sulfuric-acid railcar accident (Richmond, CA)
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Workers overheated a railroad car while attempting to transfer liquid oleum (saturated sulfuric acid). The safety valve blew, releasing eight tons of sulfuric acid to the air.

ARAC delivered accurate predictions of the inhalation hazard to local and state agencies using real-time local meteorology and the estimated quantity of material released.

1993 - Tomsk-7 waste-tank explosion (USSR)
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ARAC used weather forecasts provided by the U.S. Air Force to predict the regional extent of uranium and plutonium released when a waste tank exploded at the Tomsk-7 Russian nuclear facility. The cloud moved toward unpopulated areas northeast of the city.

1991 - Mt. Pinatubo eruption (Philippines)
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During multiple volcanic eruptions of Mt. Pinatubo, ash clouds reached heights of 90,000 feet. ARAC provided forecasts to assist in determining safe flight routes for the U.S. Air Force evacuation of 20,000 U.S. military personnel and citizens.

1990 - Ulysses spacecraft launch (Kennedy Space Center, FL)
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ARAC was a crucial DOE asset supporting NASA's launch of the Ulysses spacecraft from the Space Shuttle Discovery. Powered by a Radioisotope Thermoelectric Generator, Ulysses acquired solar data for 18 years.

1999 - Nuclear-fuel criticality accident (Tokaimura, Japan)
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Workers at a nuclear fuel-processing plant in Tokaimura, Japan, were adding enriched uranium to a precipitation tank when they saw a blue flash, indicating the initiation of a nuclear chain reaction.

NARAC modeled the radioactivity released into the atmosphere from this criticality accident and advised that the radiological hazard did not extend beyond the facility.

1998 - Cesium release from steel mill (Algeciras, Spain)
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In June 1998, radiological monitoring stations in Europe detected small amounts of cesium in the atmosphere. NARAC staff analyzed these measurements to reconstruct the event and develop model predictions consistent with the data.

The center's estimate of the source location, release time and the quantity of cesium involved were verified when Spanish authorities determined that a medical radiotherapy source had been accidentally melted in a scrap steel mill near Gibraltar on May 30.

1997 - European Tracer Experiment (ETEX)
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NARAC participated in an international blind test of the ability of models to simulate dispersion on a continental scale, motivated by the Chernobyl accident. Experimentally measured air concentrations produced by a controlled atmospheric release of an inert gas in Europe were used to assess model performance. NARAC was one of the top performing models.

1996 - Train accident with multiple releases (Cajon Pass, CA)
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On February 1, 1996, several tank cars on a derailed train in Cajon Pass, California, began leaking hazardous chemicals. ARAC delivered a 30-hour forecast of the expected impacted areas to the California Office of Emergency Services field teams, greatly assisting emergency planning.

1995 - Peacekeeper launches (Vandenberg Air Force Base, CA)
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ARAC provided Vandenberg Air Force Base with estimates of the potential health effects from missile exhaust clouds. An analysis based on these accurate calculations saved the LLNL Peacekeeper Test Program millions of dollars a day.

1991 - Railcar spill (Sacramento River, CA)
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A derailed train spilled 19,000 gallons of soil fumigant near Dunsmuir, California. The spill entered the Sacramento River and produced toxic gases as it flowed downstream.

ARAC provided a forecast to the California Office of Emergency Services that indicated an evacuation of the Lake Shasta area would not be necessary. This forecast was later verified by measurements.

1991 - Kuwaiti oil-field fires (Persian Gulf)
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For six months after the first Gulf War, ARAC delivered twice-daily ground-level smoke concentration forecasts to 17 agencies and countries in the Persian Gulf region to help assess air-quality conditions. This was one of ARAC's first responses utilizing regional forecast models outside the U.S.

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During the 1980s


1989 - Galileo spacecraft launch (Kennedy Space Center, FL)
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ARAC deployed as part of DOE's support of NASA's first launch of an interplanetary spacecraft powered by a Radioisotope Thermoelectric Generator. Galileo provided the first detailed survey of Jupiter.

1988 - Rocket-fuel plant explosion (Henderson, NV)
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ARAC provided emergency managers with estimates of the regional extent of the toxic smoke cloud resulting from an explosion and fire at the Space Shuttle solid rocket booster plant.

1986 - Sequoyah Fuels UF6 accident (Gore, OK)
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Workers heating an overfilled cylinder of uranium hexafluoride caused a rupture and release of toxic gases resulting in injuries to on-site personnel. ARAC estimates of the downwind extent of the cloud were later verified against Nuclear Regulatory Commission measurement data.

1983 – 1999 - Second-Generation ARAC System

The second-generation ARAC system added capabilities to allow model simulations to be easily run anywhere in the country. The system used desktop computers at up to 70 remote sites and a dedicated ARAC central computer system at LLNL.

1980 - Titan II missile accident (Damascus, AR)
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A mechanic dropped a two-foot-long wrench onto a Titan II missile in a silo at Damascus, Arkansas, igniting the hydrazine tank and blowing the warhead a half kilometer away.

ARAC developed estimates of the hazard from the hydrazine release and what-if radiological dispersal calculations in case the weapon was involved in an explosion. Fortunately, the warhead remained intact.

1989 - Tritium release (DOE Pantex Plant, TX)
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The DOE emergency response staff at the Pantex Plant called upon ARAC to estimate the dispersion of tritium gas released from an on-site building. ARAC provided predictions of a complex plume resulting from a multi-hour release during the passage of a weather front.

1988 – Present - NNPP and SWF Support

NARAC provides emergency-response atmospheric plume modeling tools and services to the Naval Nuclear Propulsion Program (NNPP) and Strategic Weapons Facilities (SWF). Initially, LLNL developed and deployed specialized site workstation software to these sites, later replaced by the NARAC iClient and Web.

1986 - Chernobyl reactor accident (USSR)
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A partial core meltdown at the Chernobyl nuclear power plant in the Soviet Union resulted in an explosion that blew the 2000-ton lid off the reactor core. Millions of curies of iodine and cesium were released.

Over the next 16 days, ARAC estimated the activity released, modeled the transport and deposition of the material involved, and estimated the dose to people in Europe and around the globe.

1983 - Russian Cosmos 1962 nuclear satellite re-entry (Indian Ocean)
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ARAC provided predictions of the dispersal of material from the uncontrolled re-entry of a Russian nuclear-powered satellite. Satellite debris landed in the Indian Ocean.

1980 – Present - Chemical and Biological Agent Modeling
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ARAC began development of toxic industrial chemical (TIC) modeling capabilities in the 1980s. In subsequent years, LLNL added an extensive set of TIC, chemical warfare and biological agent material property databases; release models for chemical and biological agent dispersal (sprayers, moving vehicles, etc.); and dose- and health-effect level information that are used to estimate the potential impacts of industrial and transportation accidents and terrorist attacks.

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During the 1970s


1979 — 1983 - First-Generation ARAC System

The original ARAC computer system was the first operational system using advanced 3-D models for emergency planning and response. The system employed mini-computers at LLNL and seven DOE remote sites and LLNL supercomputers for computational modeling.

1979 - Foundation of the ARAC Operational Center
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On March 29, 1979, DOE called on LLNL to use its prototype modeling system to respond to the Three Mile Island nuclear power plant accident. The center became operational on April 1, 1979 and has continued to serve as DOE's plume modeling center since that time.

1978 - Chinese atmospheric nuclear weapon tests
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LLNL scientists estimated the path of nuclear debris from the last set of Chinese atmospheric nuclear-weapons tests in the remote Lop Nur region.

1970s - LLNL regional and global models

In the 1970s, LLNL conducted leading-edge research on modeling of wind flow and dispersion in complex terrain and developed state-of-the science regional and global atmospheric transport and fallout models, including:

  • 2BPUFF global atmospheric transport model
  • KDFOC nuclear fallout model
  • LIRAQ regional air quality model

LLNL conducted leading-edge research on modeling of wind flow and dispersion in complex terrain. ARAC's TOPOG, MEDIC/MATHEW (mass consistent wind field) and ADPIC (particle-in-cell dispersion) computer codes became the first 3-D complex-terrain models developed to run in near-real-time as part of an emergency response system.

1979 - Three Mile Island Reactor Accident, PA
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The most serious nuclear power accident in the U.S. occurred at the Three Mile Island Nuclear Generating Station near Harrisburg, Pennsylvania. Utilizing the newly developed ARAC modeling system, LLNL generated maps that were used to guide DOE and state measurement teams in determining the impacts from the radiological material released. This event was ARAC's first major response.

1978 - Operation Morning Light (Canada)
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For several months, an LLNL team followed the steady decline of the orbit of a Soviet Cosmos satellite powered by a nuclear reactor and calculated possible contamination footprints in case of re-entry. On January 16, 1978, the satellite crashed in a remote area of northern Canada. Over the next several weeks, U.S. aerial and ground survey crews assisted the Canadian clean-up effort Operation Morning Light.

1973 - Creation of ARAC (LLNL, CA)
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The Atmospheric Release Advisory Capability (ARAC) began as a DOE feasibility study in 1973. Over the next five years, LLNL developed a prototype emergency response system that combined meteorological and dispersion models to provide reliable and timely dose-assessment advisories to emergency managers at DOE nuclear facilities and U.S. nuclear power plants.


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