Unacceptable Risk: Two Decades of “Close Calls,” Leaks and Other Problems at U.S. Nuclear Reactors

As the eyes of the world have focused on the nuclear crisis in Fukushima, Japan, Americans have begun to raise questions about the safety of nuclear power plants in the United States.


Iowa PIRG Education Fund

As the eyes of the world have focused on the nuclear crisis in Fukushima, Japan, Americans have begun to raise questions about the safety of nuclear power plants in the United States.

American nuclear power plants are not immune to the types of natural disasters, mechanical failures, human errors, and losses of critical electric power supplies that have characterized major nuclear accidents such as the one at Fukushima Daiichi power plant in Japan. Indeed, at several points over the last 20 years, American nuclear power plants have experienced “close calls” that could have led to damage to the reactor core and the subsequent release of large amounts of radiation.

These incidents illustrate the inherent dangers of nuclear power to people and the environment, and demonstrate why the United States must move away from nuclear power and toward safer alternatives.

On four occasions since 1990, the U.S. Nuclear Regulatory Commission (NRC) has rated a reactor event as a “significant precursor” of core damage – meaning that the chance of an accident that would damage the reactor core, and possibly lead to a large-scale release of radiation, increased to greater than 1 in 1,000. These events had a number of causes, including operator error, primary equipment degradation or failure, failure of emergency backup systems, and loss of offsite power.

  • In 2002, in perhaps the most dangerous nuclear incident in the United States since Three Mile Island, workers at the Davis-Besse Nuclear Generating Station in Ohio discovered that boric acid leaking from a cracked nozzle had eroded away six inches of carbon steel on the reactor vessel head, leaving only 3/8 inch of stainless steel to contain the reactor’s highly pressurized steam. Rupture of the vessel head could have resulted in the loss of coolant and damage to the plant’s control rods, creating the conditions for rapid overheating of the reactor core and possible release of radiation.
  • In 1996, critical systems at a reactor at Catawba Nuclear Station in South Carolina were without power for several hours when the plant lost outside power at the same time that one of its emergency generators was out of service for maintenance.
  • In 1994, workers accidentally allowed 9,200 gallons of coolant to drain from the core of a reactor at Wolf Creek nuclear power plant in Kansas. The plant’s operators estimated that the condition – had it persisted for five more minutes – could have led to the plant’s fuel rods being exposed and put at risk of overheating.
  • In 1991, valves and drain lines in an emergency shutdown system failed at the Shearon Harris nuclear power plant in North Carolina. Had an emergency occurred during that failure, the plant may not have been able to be shut down safely.

At least one out of every four U.S. nuclear reactors (27 out of 104) have leaked tritium – a cancer-causing radioactive form of hydrogen – into groundwater. Among the accidental releases of radioactive material from U.S. nuclear power plants in the past decade are:

  • The leakage of radioactive material into groundwater at New Jersey’s Salem nuclear power plant – a leak that was discovered in 2002 after it had already been going on for five years. Subsequently, a similar leak of tritium was discovered at New Jersey’s Oyster Creek power plant just one week after the plant received a 20-year license extension.
  • The leakage of radioactive tritium into groundwater at the Braidwood Nuclear Generating Station in Illinois.
  • The leakage of both tritium and radioactive strontium from the spent fuel pools at the Indian Point Energy Center in New York, which are located just 400 feet from the Hudson River.
  • The discovery of tritium in groundwater near the Vermont Yankee nuclear power plant, even though the plant’s owner, Entergy, had stated several times in sworn testimony that the plant had no subterranean pipes capable of leaking radioactive material.

In recent years, American nuclear power plants have frequently been forced to rely on safety systems to react to unexpected events. However, these safety systems often fail to work as expected.

  • Safety systems are the emergency diesel generators and emergency cooling systems that activate if the reactor loses power or needs to shut down rapidly.
  • In 2009, approximately 70 failures in key safety systems were found at U.S. nuclear reactors. That same year, U.S. reactors were required to activate safety systems approximately 24 times. Should these two types of events overlap at the same facility, a serious problem could result.

To protect the public from the inherent dangers of nuclear power, the United States should take a “time out” on nuclear relicensing and construction until safety problems at nuclear plants are fully addressed, and move away from nuclear power as a major source of America’s energy.

Specifically, President Obama should call for:

  • Completion of a comprehensive safety review of all 104 operating U.S. nuclear reactors.
  • A moratorium on the relicensing of existing, aging nuclear power plants – some of which share a similar design to the reactors in Fukushima, Japan.
  • A moratorium on the licensing of new nuclear reactors.
  • Elimination of federal loan guarantees and other subsidies for nuclear power plants. Taxpayers should not be required to subsidize inherently dangerous technologies such as nuclear power – instead, those incentives should be targeted toward low-risk forms of energy such as solar and wind power and improved energy efficiency.