Emergency Planning for Nuclear Disasters

If a nuclear power accident occurs in the U.S., are we ready?

Published Dec 1, 2011 Updated Dec 2, 2011


One hundred and twenty million Americans live within 50 miles of a nuclear power plant. Fortunately, a serious accident at one of these plants is highly unlikely. But as we saw at Fukushima, sometimes the unlikely is what happens, and we must be prepared to respond when it does.

Who is responsible for emergency planning?

Emergency planning responsibilities for nuclear power plants fall into two categories: onsite (responding to the accident within the nuclear facility itself) and offsite (dealing with the consequences to the surrounding area and population).

According to guidelines prepared by a joint NRC/FEMA task force after the Three Mile Island accident in 1979, power plant owners are responsible for onsite emergency planning, while state and local governments are responsible for offsite emergency planning. The NRC has overall authority for final review in both cases.

The NRC reviews onsite emergency response planning and training procedures as part of a nuclear plant's initial licensing process, and plant owners are required to exercise their emergency plans with the NRC, FEMA, and offsite authorities at least once every two years. A number of different state and federal agencies, ranging from state health departments to the Department of Homeland Security, are involved in the process of preparing and approving offsite emergency response plans.

Emergency response measures

In the event of a nuclear power plant accident, plant personnel are required to immediately notify state and local authorities and the NRC. State and local emergency management agencies then decide what measures are needed to protect the public. They may order an evacuation of the area surrounding the plant, or advise residents to shelter in place to minimize radiation exposure. They may also distribute potassium iodide (KI) tablets to help reduce long-term cancer risk.

Emergency planning zones

Federal emergency planning criteria specify two types of emergency planning zones (EPZ):

  • a 10-mile EPZ, called the plume exposure pathway, where people could be harmed by direct radiation exposure, requiring protective measures such as evacuation or sheltering;
  • a 50-mile EPZ, called the ingestion exposure pathway, where the primary concern is contamination of water and food supplies, with evacuation at the discretion of local authorities.

This distinction received heightened attention during the Fukushima crisis, when the U.S. advised Americans living within 50 miles of the power plant to evacuate—suggesting a disconnect between emergency planning guidelines and actual practice in the event of an accident.  

UCS recommendations

The NRC should ensure that everyone at significant risk from an accident—not just people within the arbitrary 10-mile EPZ—is protected in the event of a nuclear disaster. Just as the U.S. government advised Americans within 50 miles of Fukushima to evacuate, an accident at a U.S. reactor could similarly require evacuation of people outside the 10 mile EPZ and other protective measures to avoid high radiation exposures. The NRC should therefore require reactor owners to develop emergency plans for a larger area, based on a scientific assessment of the populations at risk for each reactor site.

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