Frequently Asked Questions About Emergency Preparedness and Response

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About Emergency Preparedness

Index to All Frequently Asked Questions Pages

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What is emergency preparedness?

Emergency preparedness means taking action to be ready for emergencies before they happen. The objective of emergency preparedness is to simplify decisionmaking during emergencies. Over the years, the combined efforts of the NRC, FEMA, nuclear power plant operators, State and local officials, as well as thousands of volunteers and first responders (such as police, firefighters, and medical response personnel), have produced comprehensive emergency preparedness programs that assure the adequate protection of the public in the event of a radiological emergency. The emergency preparednessprocess incorporates the means to rapidly identify, evaluate and react to a wide spectrum of emergency conditions. Emergency plans are dynamic and are routinely reviewed and updated to reflect an ever changing environment.

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How has emergency preparedness changed since the September 11, 2001, attacks?

After the terrorist attacks of September 11, 2001, emergency preparedness was strengthened. For example, NRC has verified that its regulations and guidance are appropriate for all types of emergency events, including terrorism. On the State and local level, many communities are upgrading their emergency response capabilities and modernizing communication systems, developing transportation analyses and assessments to improve traffic flow, improving local education and awareness, and developing interagency and cross-boundary coordination plans. These enhancements will improve emergency response whether the initiating event is a natural disaster or a terrorist act. For more information, see the Fact Sheet on Safety and Security Improvements at Nuclear Plants.

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Who is responsible for emergency preparedness oversight?

The NRC is responsible for oversight of a nuclear facility's emergency preparedness, and FEMA is responsible for oversight of preparedness outside the nuclear facility’s boundary. The NRC issues reactor operating licenses, which require an acceptable, integrated emergency plan (i.e., both onsite and offsite planning) that provides reasonable assurance that adequate protective measures can, and will, be taken in the event of a radiological emergency.

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What are the regulations governing emergency preparedness for nuclear reactors?

Emergency planning for the existing nuclear power plants, licensed under the 10 CFR Part 50 process, is evaluated under 10 CFR 50.47, Appendix E to Part 50, and includes the guidance in NUREG-0654/FEMA-REP-1, Rev. 1. For more information, see our Regulations, Guidance, and Generic Communications Web page.

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Will the emergency planning requirements for new nuclear power reactors be any different from those for currently operating reactors?

The requirements for emergency planning established in 10 CFR Part 50 and associated guidance will be applicable to new reactors.

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How do I know that NRC licensees are complying with emergency preparedness regulations and guidance?

The NRC performs oversight of emergency preparedness through performance indicators and through inspection. NRC inspectors dedicate thousands of hours to routine inspections, observations of drill and exercises, review of licensee corrective actions, as well as emergency plan changes. In addition, licensees are required to conduct a full-scale exercise involving Federal, State, and local agencies every two years. These exercises are evaluated by the NRC and FEMA. The results and, if necessary, enforcement of these emergency preparedness oversight activities are available for public review and can be found on the NRC Operating Reactor Oversight Web page.

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How are NRC Inspectors qualified to inspect for emergency preparedness?

NRC emergency preparedness inspectors are trained through a rigorous two-year qualification program which includes formal coursework and numerous inspections. The qualification process ends with each inspector sitting for a qualification board of senior subject-matter experts. Additionally, many of NRC's emergency preparedness inspectors have prior experience in the nuclear industry so they have first-hand knowledge of NRC policies and licensee programs. Emergency preparedness inspector qualification requirements are found in Manual Chapter 1245, Appendix C6.

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What is "reasonable assurance"?

Reasonable assurance is the recognition that “adequate protective measures can and will be taken in the event of a radiological emergency.” Reasonable assurance is based on licensees complying with NRC regulations and guidance, as well as licensees and offsite response organizations demonstrating that they can effectively implement emergency plans and procedures during periodic evaluated exercises.

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What happens if the NRC does not make a finding of reasonable assurance?

When, as described, in 10 CFR 50.54(s)(2)(ii) and 50.54(s)(3) of its regulations, the NRC finds the state of emergency preparedness does not provide reasonable assurance that adequate protective measures can and will be taken in the event of a radiological emergency, the NRC will notify the affected licensee accordingly and start the"120-day clock." If after four months ("120-day clock") the deficiencies are not corrected, the Commission will determine whether the reactor shall be shut down until such deficiencies are remedied or whether other enforcement action is appropriate.

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How can the public become involved in the emergency planning and preparedness process?

One way is by attending public meetings hosted by the NRC. The public can keep abreast of NRC's regulatory activities through a variety of open meetings, including Commission meetings, advisory committee meetings, hearings, and staff meetings open to the public. The latter includes most technical meetings with licensees, trade organizations, and public interest groups. For the most current list of scheduled public meetings, see our Public Meeting Schedule page.

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What are the 10-mile and 50-mile emergency planning zones?

Two emergency planning zones (EPZs) around each nuclear power plant help plan a strategy for protective actions during an emergency. The plume exposure pathway EPZ has a radius of about 10 miles from the reactor. Predetermined protection action plans are in place for this EPZ and are designed to avoid or reduce dose from potential exposure of radioactive materials. These actions include sheltering, evacuation, and the use of potassium iodide where appropriate. The ingestion exposure pathway EPZ has a radius of about 50 miles from the reactor. Predetermined protection action plans are in place for this EPZ and are designed to avoid or reduce dose from potential ingestion of radioactive materials. These actions include a ban of contaminated food and water.

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Will radiation from a nuclear power plant accident spread out over the entire 10-mile EPZ?

A radioactive plume (cloud with radioactive materials discharged from the nuclear power plant during an accident) travels in the same direction as the wind rather than spread out over the entire 10-mile EPZ. The plume characteristics are determined by natural environmental factors, such as wind speed, wind direction, turbulence due to solar heating, humidity, and ground temperatures. As radioactivity enters the plume, it travels downwind and expands in the horizontal and vertical directions. The expansion of the plume causes the concentration of the radioactivity in the plume to decrease with increasing downwind distance. The radiation dose to persons in the plume is a function of the concentration of the radioactivity at any point in the plume. So, as the plume expands downwind, the concentration decreases as does the radiation dose.

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What if conditions don't allow for an evacuation?

Evacuation is not the only protective action available to the public. In some situations sheltering may provide protection that is equal to or even greater than evacuation. Sheltering may be the preferred protective action in cases where weather, competing events, or short-term releases are factors.

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What are evacuation time estimates?

Evacuation time estimates are tools to assist offsite authorities to determine evacuation routes, traffic control plans,and impediments to traffic flow. These time estimates are used by State and local authorities when they make protective action decisions. Under inclement weather conditions, the time to evacuate may be longer, so the decision may be made only to evacuate a small portion of the area and advise sheltering for the remainder of the population. Evacuation time estimates are not linked, in any way, to the doses at which protective actions are recommended.

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Will sheltering result in a higher radiation dose than evacuation?

When the public evacuates, they are removed from further exposure to radioactive materials, and under most conditions, evacuation is preferred. However, there are many instances where sheltering may be the preferred protective action. Sheltering may provide protection that is equal to or greater than evacuation, taking into consideration such factors as weather, competing events, fast-breaking or short-term release, or traffic considerations. As an example, during a relatively short term release, it may be prudent to recommend that the population shelter in place, such as at home, the office, school, or shopping mall. Depending on the type of building, sheltering can result in a radiation dose reduction of up to 80% compared to being outdoors.

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Have there been any evacuations as a result of nuclear emergencies?

There has been only one nuclear emergency that resulted in an evacuation since the first nuclear power reactor started producing power in 1957. The accident at the Three Mile Island Unit 2 (TMI-2) nuclear power plant near Middletown, Pennsylvania, on March 28, 1979, was the most serious in U.S. commercial nuclear power plant operating history. The evacuation was recommended for pregnant women and preschool-age children within a 5-mile radius of the plant.

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What are "shadow evacuations"?

The term "shadow evacuations" is used to describe spontaneous evacuations by people outside of any officially declared evacuation zone(s).

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Are emergency preparedness exercises effective?

Yes, emergency preparedness exercises have been proven to be effective in the success of actual emergencies. Numerous examples, such as the emergency response to the 1989 San Francisco earthquake, have demonstrated that good training, drills, and exercises are the key to success.

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What is potassium iodide?

Potassium iodide is a salt, similar to table salt. Its chemical symbol is KI. It is routinely added to table salt to make it "iodized." Potassium iodide, if taken in time and at the appropriate dosage, blocks the thyroid gland's uptake of radioactive iodine and thus could reduce the risk of thyroid cancers and other diseases that might otherwise be caused by exposure to radioactive iodine that could be dispersed in a severe nuclear accident.

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What is the role of potassium iodide in radiological emergency preparedness?

The purpose of radiological emergency preparedness is to protect people from the effects of radiation exposure after an accident at a nuclear power plant. Evacuation is the most effective protective measure in the event of a radiological emergency because it protects the whole body (including the thyroid gland and other organs) from all radionuclides and all exposure pathways. However, in situations when evacuation is not feasible and in-place sheltering is substituted as an effective protective action, administering potassium iodide is a reasonable, prudent, and inexpensive supplement to evacuation and sheltering.

Potassium iodide is a special kind of protective measure in that it offers very specialized protection. Potassium iodide protects the thyroid gland against internal uptake of radioiodines that may be released in the unlikely event of a nuclear reactor accident. For more information on potassium iodide (KI), see our Frequently Asked Questions About Potassium Iodide Web page.

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Why is KI only being provided to the 10-mile EPZ around nuclear power plants?

The population closest (within the 10-mile EPZ) to the nuclear power plant is at greatest risk of exposure to radiation and radioactive materials. The purpose of radiological emergency preparedness is to protect people from the effects of radiation exposure after an accident at a nuclear power plant. Evacuation is the most effective protective measure in the event of a radiological emergency because it protects the whole body (including the thyroid gland and other organs) from all radionuclides and all exposure pathways. However, in situations when evacuation is not feasible, in-place sheltering is substituted as an effective protective action. In addition, administering potassium iodide is a reasonable, prudent, and inexpensive supplement to both evacuation and sheltering. When the population is evacuated out of the area, and potentially contaminated foodstuffs are prohibited, the risk from further radioactive iodine exposure to the thyroid gland is essentially eliminated.

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Will KI be effective in case of a terrorist attack or dirty bomb?

In a terrorist attack either at a nuclear power plant or with a dirty bomb, radioactive iodine would have to be released in order for potassium iodide (KI) to be needed. Potassium iodide protects the thyroid gland only against the internal uptake of radioiodines.

A nuclear power plant will make protective action recommendations based on current emergency plans, which may include the recommendation to take KI as a supplement to evacuation and/or sheltering. In the case of a dirty bomb, protective actions will be made according to the threat presented. If the bomb contained radioactive iodine, then the use of KI may be appropriate. However, radioactive iodine is not considered to be a viable component of a dirty bomb due to its relatively short half-life and the difficulties in obtaining significant quantities. More information on dirty bombs and response to terrorist activities can be found on the Nuclear Security and Safeguards web page. Other information can be found at the Department of Homeland Security.

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About Emergency Response

Index to all Frequently Asked Question Pages

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If I see a radioactive symbol on a box or container which is not in the custody of a responsible person, whom should I notify?

Please notify your FEMA’s State Offices and Agencies of Emergency Management, or the U.S. NRC to Report a Safety Concern.

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What's the difference between "emergency preparedness" and "emergency response"?

Emergency preparedness generally refers to actions which can and should be performed prior to an emergency. Actions, such as planning and coordination meetings, procedure writing, team training, emergency drills and exercises, and prepositioning of emergency equipment, all are part of "emergency preparedness."

Emergency response refers to actions taken in response to an actual, ongoing event. Good planning leads to organized and effective emergency response.

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What kinds of emergencies could occur at a nuclear facility?

Similar to other industrial facilities, a nuclear facility may encounter failures involving mechanical equipment, electrical power, instrumentation and control systems, or personnel error. Although significant efforts are made to minimize these occurrences, it is certainly prudent to assume that failures will occur, and that plans and procedures should be in place to prevent the initial failure from causing additional failures or threatening public health and safety.

Nuclear facilities contain radioactive materials within systems, structures, or components commonly referred to as "barriers." Several of these barriers must fail before a significant release of radioactive materials can occur. The severity of an emergency at a nuclear facility then, can be linked to the number of radiation barriers which are being threatened or have been damaged. 

Nuclear power plants, research and test reactors, nuclear materials licensees, and fuel cycle facilities use emergency classifications to indicate a level of risk to the public. For more detailed information, see our Emergency Classification Web page.

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Are all NRC licensees required to have offsite emergency response plans?

Yes. All NRC licensees are required to provide reasonable assurance that adequate measures can and will be taken in the event of an emergency. For nuclear power plants, both onsite and offsite emergency response plans are required. This is because a severe accident at a nuclear power plant could reasonably be expected to impact individuals located some distance away from the power plant.

For large fuel cycle and material facilities, only an onsite emergency response plan is required. No offsite response plan is needed since accidents at these facilities are not expected to impact individuals located much beyond the site boundary. (This arrangement is similar to that of other industrial facilities in which accidents are dealt with by offsite firefighters and police routinely without a formal offsite response plan.)

For smaller licensees, no formal response plans are required since accidents would have no significant impact outside the facility. These licensees are required to have appropriate internal procedures in place to protect workers and control radioactive materials.

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What is a "meltdown"? Can a meltdown be prevented?

A nuclear reactor is fueled with many thousands of ceramic uranium pellets located within 12-foot long metal fuel rods. As the reactor performs its intended function (uranium atoms fission, releasing heat energy, generating steam for electrical power production) many of the uranium atoms are converted into new atoms which are highly energetic and highly radioactive. Under normal conditions these highly radioactive "fission products" remain safely within the confines of the metal fuel rod. During a severe malfunction, it is possible that the energy released by the fission products could be sufficient enough to damage the metal fuel rod, and even melt the ceramic fuel pellet itself. Diagram of fuel pellet, metal fuel rod, and nuclear fuel assembly.

Fuel pellet melting is a significant concern because it indicates that multiple protection systems and radiation barriers have failed and that other systems and barriers are about to be challenged. Accidents of this magnitude are classified at the highest severity level (general emergency).

A meltdown is prevented by ensuring that sufficient cooling water is always available to remove fission product heat from the reactor. Multiple water systems, pumps, and flow paths are maintained to ensure that water will always be available for this purpose. But in case all these precautions fail, the emergency response organization must always be ready.

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Are nuclear facilities required to notify the NRC and offsite authorities if conditions indicate that an emergency is underway (or might develop?)

Yes. Those requirements can be found in Title 10 of the Code of Federal Regulations, Part 50.72. Any situation which would result in one of the four emergency classes must be immediately communicated to State and local emergency response officials, and then to the NRC Operations Center.

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What are the reporting requirements for NRC licensees and certificate holders?

Please refer to NRC's Reporting Requirements page.

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What is the International Nuclear Event Scale?

The International Nuclear Event Scale (INES) is a tool intended to promptly and consistently communicate to the public the safety significance of reported events at nuclear installations. For more details, see our International Nuclear Event Scale Web page.

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Does the NRC participate in the INES system?

The NRC has participated in the INES since 1993. Under this participation, the NRC rated all events at reactor facilities which resulted in the declaration of an Alert or higher emergency classification. A total of 32 INES reports were transmitted to the IAEA during the period from February 1993 through September 2001. In 2001, the NRC modified its level of participation in the INES to include the review of all events, including materials and transportation events, for potential rating using the INES. The NRC staff has developed methods and procedures to incorporate the INES rating process into the agency's events assessment program.

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How often does the NRC participate in emergency response exercises?

NRC Headquarters typically participates in five emergency response exercises each year, selected from among the list of full-scale, FEMA-graded exercises required of each U.S. nuclear power plant and fuel facility. On-scene participants include the NRC licensee, NRC Regional personnel, State, county, and local emergency response agencies. NRC also observes the onsite licensee response during the exercise. FEMA reviews the offsite response under the emergency plan implemented by the local and State governments. NRC will also participate in approximately six other exercises each year. This participation is usually performed with only regional staff. See Emergency Exercise Schedule.

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What's the difference between a "drill" and an "exercise"?

A drill is a test of a portion of the response organization (for example, a fire drill tests a facility's firefighting teams and the individuals in the vicinity of the area selected for that particular drill). An "exercise" typically tests many facets of the response organization and often involves close coordination between licensee (onsite) and State and local (offsite) response organizations.

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Do other Federal agencies participate in these exercises?

Typically, other Federal agencies receive notification and regular status updates during an exercise. Several agencies send representatives to the NRC Operations Center to assist NRC in simulating a coordinating Federal response under the Nuclear/Radiological Incident Annex to the National Framework Plan. Other agencies who respond include the following:

The Department of Homeland Security (DHS), is kept informed of an event status. DHS may require NRC staffing of the Homeland Security Operations Center (HSOC) to increase coordination and reach-back capability.

The Federal Emergency Management Agency (FEMA), which is responsible for coordinating the non-radiological portion of the federal offsite response. FEMA becomes especially active if the President declares that the event is a major emergency under the Stafford Act.

The Department of Energy (DOE), which can conduct overflights to assess the extent of radiation releases offsite. DOE also establishes a Federal Radiological Monitoring and Assessment Center or FRMAC to coordinate all radiological measurements from various field teams. The FRMAC helps ensure that decisions about protecting people will be made using all available and assessed data.

The Department of Agriculture (USDA), decides when livestock should be placed on stored feed or sheltered and makes other decisions regarding the food supply.

The Department of Health and Human Services (HHS), is involved for general health concerns.

The Environmental Protection Agency (EPA), addresses non-radiological environmental hazards associated with the response (e.g., chemical releases, oil spills).

The National Oceanographic and Atmospheric Administration (NOAA), supports the response by providing weather condition advisories.

The Department of State (DOS), will notify other countries under the notification protocols we have established. The NRC can notify Mexico and Canada directly, and also notifies the International Atomic Energy Agency (IAEA) for distribution to other countries.

The Federal Bureau of Investigation (FBI), becomes involved if criminal activities have occurred or are threatened on or near the nuclear facility.

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Who makes the decision for people to take shelter or evacuate if an emergency were to occur?

The State (or in some cases, a county or local official) makes the decision, based on information from the licensee. The State (local) officials may discuss the situation with NRC and seek its advice, but the ultimate decision is the responsibility of the State (or local) official. For more information, see FEMA’s State Offices and Agencies of Emergency Management.

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How will people learn if they need to take shelter or evacuate?

Persons located within about a ten-mile radius of a nuclear facility will be notified by means of sirens, tone-alert radios, and similar alert mechanisms. Persons living in the vicinity of a nuclear power plant must be advised annually regarding how they should respond and the procedures that they should follow. This is part of the licensee's Emergency Preparedness Plan, which the NRC and the Federal Emergency Management Agency (FEMA) must review and approve.

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How does the NRC investigate incidents or events that happen with their licensees?

Incident investigation is a formal process conducted for the purpose of accident prevention. The NRC Incident Investigation program provides a formal, structured, and appropriately measured NRC investigative response to significant operational events based on their safety significance. This process includes gathering and analyzing information; determining findings and conclusions, which include the causes of a significant operational event; and disseminating the investigation results for NRC, industry, and public review. NRC Management Directive 8.3, NRC Incident Investigation Programprovides the details of this process.

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How does the NRC track licensee events and share potential generic issues with the industry?

The NRC staff evaluates event reports to identify significant weaknesses in plant design and operation, or equipment problems that may systematically affect several plants of a given design. When Generic Safety Issues are identified, NRC staff formally tracks them, and may initiate formal communications with industry stakeholders to provide awareness and resolution of such issues.

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How does the Federal government respond to a radiation emergency?

The Federal Government’s response to a radiation emergency is guided by the National Response Framework, which is an all hazards plan for domestic incident response.

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Where can I get more information about radiation?

Please refer to NRC's Radiation Protection page.

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If I have a safety concern, whom should I call?

Please refer to Report a Safety Concern.

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Page Last Reviewed/Updated Friday, November 19, 2021