Mapping Fallout from Severe Nuclear Power Plant Accidents in the United States

The nuclear accident at the Fukushima-Dai’ichi nuclear plant in Japan, which began nearly one year ago, on March 11, 2011, has had a major impact on how Americans view the risks of nuclear power. The explosion and fire at the Chernobyl reactor in Ukraine a quarter century earlier also spurred strong U.S. responses, but it may have seemed further removed because that accident occurred in the context of the Cold War, in a country that tightly controlled information, and at a reactor that, unlike Western reactors, had no containment structure. The Japanese catastrophe felt closer to home: people watched the Fukushima accident unfold in real time in a modern democratic society which has a nuclear regulatory agency not very different from that in the U.S., and Fukushima involved types of reactors we also have operating in this country.

During the first days of the unfolding Japanese accident, I recall driving home from work in D.C. and listening to a radio report from a semi-deserted, darkened Tokyo, where skyscrapers swayed slightly in the earthquake’s aftershocks and radiation levels in the city were slowly rising. For me, Fukushima also brought back memories from my childhood when my family evacuated during the Three Mile Island accident in 1979. And I found myself wondering, how can Americans better understand the extent of the risks posed by nuclear power in the U.S. to their homes and families now?

One idea that came to us at NRDC was to create an online map showing the location of the 104 nuclear reactors at 65 power plants in the United States, and overlaying the radiation effects of a severe nuclear accident at any of these sites. We added to this information as to what in our judgment are heightened risk factors for severe accidents at certain plants – “red flags” – and also showed 10-mile and 50-mile zones around the plants.

The details of what would happen in a severe nuclear accident in the U.S. are impossible to predict with certainty. The government’s10-mile evacuation zone is a rough estimate of how far imminently dangerous, higher levels of radiation could spread in a severe accident; however wind and other aspects of the weather would determine the actual path and distance fallout would travel in the immediate aftermath of a crisis.

Fukushima is a pertinent example of this: the highest levels of contamination were along a plume that extended some 50 miles from the plant in the northwest direction. This fallout pattern was determined by wind direction during a progression of specific events, like hydrogen explosions, over the course of days. And at one point early on in the Fukushima accident progression, the Japanese government advised that Tokyo citizens not use tap water to make baby formula because rain was flushing fallout into the city’s water supply.

Given the uncertainty of what the weather patterns would be at the time of a nuclear accident in the U.S., we used historical weather data measured across the country for the specific days of March 11 and March 12, 2011 to compute the nuclear fallout patterns if a severe nuclear accident had occurred in the United States on the same days as when Fukushima began.

Heightened risk factors for a severe nuclear accident

The “red-flag” information in the popup windows for the 65 nuclear plants in NRDC’s online map indicate three categories of heightened risk: whether the reactor units are Boiling Water Reactors (BWRs); whether they have been re-licensed to operate 60 years; and whether the NRC has allowed the reactor operators to increase their power beyond their original designs.

In NRDC’s online map at each nuclear plant we also show the officially-defined 10-mile evacuation zone set by the Nuclear Regulatory Commission, as well as 50-mile zone which is the distance the U.S. recommended Americans abroad evacuate from the Fukushima plant after last year’s accident and a distance that conveys a more realistic picture of threat. We also counted how many schools and hospitals are within these zones. In putting together this information, we compared the different nuclear power plants in the United States and assessed which could have the greatest impacts on nearby residents.

Six nuclear power plants are situated with over a quarter of a million people living within the 10-mile evacuation zones: Indian Point (NY); Limerick (PA); St. Lucie (FL); McGuire (NC); Catawba (SC); and Three Mile Island (PA). We found that approximately six million people live in the 10-mile evacuation zones around these 65 nuclear power plants, and 120 million people - or about one-third of the U.S. population - live within 50 miles of the plants.

Unfortunately, the chance of a severe accident at a U.S. nuclear power plant is a very real threat – and it wouldn’t take an earthquake and tsunami to trigger it. The fundamental cause of the disaster in Japan was that the reactors lost both primary and back-up power sources. More common weather patterns – like flooding, tornadoes and hurricanes – could have the same impact and in fact five nuclear power plants in the U.S. underwent emergency shutdowns due to such extreme weather events in 2011 as flagged in NRDC’s map.

Predicting the aftermath

As someone who works on these issues in Washington, D.C., I already knew that the nuclear power plant closest to where I live and work is Calvert Cliffs in Southern Maryland. However, working with the map has helped me assess the risks for my family and friends. For example, I typed in the addresses of where my parents live and discovered that they are in the 50-mile zones of seven reactors at four plants.

Our online map shows a wide variation in the fallout patterns from severe nuclear accidents that are dependent on weather. For example, the Indian Point nuclear reactors are within 50 miles of New York City, and on some days northerly winds would carry fallout into Manhattan. But if a severe nuclear accident had occurred on March 11-12, 2011, the winds would have first blown nuclear fallout to the northwest then shifted and blown a smaller amount of radiation to the northeast. Strong winds off Lake Michigan on those days would have carried radioactivity particularly far south from the Donald C. Cook and Palisades nuclear power plants. At River Bend Station in Louisiana, the air was still March 11-12, 2011, and so the fallout would not have spread very far from the plant.

For this project Plymouth State University’s Weather Center provided NRDC with hourly METAR-formatted National Oceanic and Atmospheric Administration (NOAA) weather reports for weather stations across the United States for the 48-hour period beginning on March 11. We performed the calculations of the nuclear fallout given this weather data using the Department of Defense computer code “HPAC,” which stands for Hazard Prediction and Assessment Capability. The code HPAC is used by emergency first responders to calculate what would happen in the event of a terrorist nuclear explosion, chemical or biological attack, or a severe industrial accident like the catastrophe at Fukushima. The code includes a database with information about specific nuclear reactors, for example their containment structures and the inventory of radioactive material in their reactor cores. Therefore the nuclear fallout calculations that NRDC shows in its online map reflect data specific to these nuclear plants, as well as to the weather in mid-March last year.

Improving safety

Now nearly one year after the Fukushima accident, NRC and industry have failed to improve safety in response to Fukushima. While an NRC taskforce identified more than 30 safety recommendations, to date they have not acted on any of them, including safety upgrades identified as the most time-urgent. My colleague, NRDC scientist Jordan Weaver, discusses the actions NRC must take to better protect the American public in greater detail here. This includes addressing concerns that arose in Fukushima, like seismic and flood issues, better protections against hydrogen explosions, and improved venting to prevent containment failure while filtering out radioactive contaminants. Jordan also urges more government transparency with the public about the risks of an accident and the potential consequences. NRDC’s online mapping tool addresses just this issue of transparency, providing a means for people to better visualize and understand the risk that nuclear power presents in their communities.

About the Authors

Matthew McKinzie

Senior Scientist, Land & Wildlife program, and Director, Nuclear program

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