After a 9.0-magnitude earthquake and 30-foot waves from a tsunami struck Japan on March 11, 2011, nuclear reactors at the Fukushima Daiichi nuclear complex in northeastern Japan started overheating and leaking radiation, raising concerns about nuclear safety and nuclear security worldwide.
People around the world watched as the death and devastation of the earthquake and tsunami were compounded by new fears of a possible nuclear meltdown that could kill, injure or damage the health of thousands of people and lay waste the local environment for decades.
In every nation where nuclear reactors provide electricity, people asked the same question: Could it happen here?
The following is a short primer that answers important questions about the relative safety and security of nuclear reactors in the United States.
U.S. Reactors Do Pose Safety and Security Risks
Like the nuclear reactors in Japan, American nuclear reactors are aging, and some are located along major fault lines and in coastal areas. Here are a few facts:
- The United States has 104 operating nuclear reactors. Thirty-five are Boiling Water Reactors. Of those, 23 reactors at 16 nuclear power plants are the same GE Mark 1 design as the reactors involved in the nuclear crisis at the Fukushima Daiichi complex in Japan.
- All nuclear reactors currently operating in the United States [as of March 2011] broke ground before 1974; no new reactors have been built in the United States since the March 1979 Three Mile Island nuclear accident in Pennsylvania.
- Long-term exposure to radiation makes steel and other metals turn brittle. Those brittle materials—the condition is called "embrittlement"—can compromise the ability of nuclear reactors, especially older reactors, to function correctly and safely.
- The Tennessee Valley Authority is considering using plutonium mixed oxide fuel (MOX) at the Browns-Ferry Mark 1 reactor, the same fuel that is used in Fukushima reactor No. 3.
- Two U.S. nuclear power plants—each with two reactors—are located on California beachfront property near the San Andreas fault, making them particularly vulnerable to earthquakes and tsunamis. The Diablo Canyon reactors were built to survive a 7.5-magnitude earthquake; the reactors at San Onofre can survive a 7.0-magnitude quake. Engineers would not expect any of the four reactors at Diablo Canyon and San Onofre to survive a more powerful earthquake without serious damage.
Radioactive Leaks and Close Calls at U.S. Nuclear Reactors
Despite numerous safeguards, equipment failure and human error have led to accidents, radiation leaks and other problems at U.S. nuclear power plants. Here are a few facts:
- In 2010, workers at the Vermont Yankee nuclear power plant discovered that aging steam pipes were leaking, sending radioactive tritium into the groundwater. Radiation was measured at 775,000 picocuries per liter, 37 times the federal limit. In all, 20 plants have reported leaking tritium into groundwater, according to Greenpeace.
- In 2002, an undetected boric acid leak at the Davis-Besse nuclear power plant in Ohio ate through most of the 6-inch-thick steel reactor head. When the leak was discovered, only 3/8 inch remained.
- The partial nuclear meltdown at Three Mile Island in 1979 occurred after the cooling system failed, causing the reactor core to overheat. As a result of security- and alarm-system failures, workers at Three Mile Island took actions that reduced cooling even more and made things worse. Fortunately, the containment building held, the amount of radiation released was minimal, and the accident caused no deaths or injuries among workers or people in the surrounding community.
The Risks of Spent Fuel at U.S. Nuclear Reactors
In the United States, as in Japan, one ever-present danger at nuclear power plants is from spent fuel rods that are no longer usable as fuel, but still highly radioactive. Here are a few facts:
- Most spent fuel rods at U.S. nuclear reactors are submerged in storage pools of circulating water to keep them cool. Unlike nuclear reactors, these storage pools are not protected by steel containment structures, even though the pools hold five to 10 times more "long-live radioactivity than a reactor," according to Dr. Robert Alvarez, a senior scholar at the Institute for Policy Studies and former senior policy adviser to the Secretary and Deputy Assistant Secretary for National Security and the Environment at the U.S. Department of Energy.
- In such storage pools—at least one of which caught fire at the Fukushima Daiichi nuclear complex in Japan—tons of spent nuclear fuel rods are submerged in circulating water to keep them cool. Absent such cooling, the spent fuel can become as hot and dangerous as fuel inside the reactors. If the pumps that keep the water moving fail, the water can boil away in as little as 24 hours, exposing the fuel rods to the air and causing a self-propagating zirconium fire and a large, uncontrolled release of radioactive isotopes.
- Submerging used nuclear fuel rods in pools of circulating water is no longer considered the safest way to store spent fuel. Germany, for example, uses the safer method of storing spent nuclear fuel in dry casks. Dry storage casks use inert gas inside heavy steel and concrete containers, which "provide leak-tight containment for the spent fuel and provide radiation shielding to workers and members of the public," according to the U.S. Nuclear Regulatory Commission. U.S. nuclear reactors currently use only a limited number of dry casks for spent-fuel storage, but the trend toward dry-cask storage is growing.
Are U.S. Nuclear Reactors Vulnerable to Sabotage and Terrorist Attacks?
Even if U.S. nuclear power plants experience no accidents, leaks or system failures, they are still potentially vulnerable to sabotage and terrorism. Here are a few facts:
- Terrorist Mohammad Atta, a ringleader of the September 11, 2001 terrorist attacks and the pilot who crashed the hijacked plane into the north tower of the World Trade Center, considered attacking a nuclear reactor. That information prompted the 9/11 Commission to recommend increasing U.S. nuclear security, but many experts believe existing security measures are still inadequate.
- In 2007, reports of security guards sleeping on the job led Exelon Nuclear, operator of the Peach Bottom Nuclear Plant in Pennsylvania, to fire its security company—but not before video of the sleeping guards appeared on television.
Sources: Friends of the Earth; U.S. Nuclear Regulatory Commission; Institute for Policy Studies