Editor's note: This is part 2 of a four-part series.
BRACEVILLE, Ill. — Radioactive tritium has leaked from three-quarters of U.S. commercial nuclear power sites, often into groundwater from corroded, buried piping, an Associated Press investigation shows.
The number and severity of the leaks has been escalating, even as federal regulators extend the licenses of more and more reactors across the nation.
Tritium, which is a radioactive form of hydrogen, has leaked from at least 48 of 65 sites, according to U.S. Nuclear Regulatory Commission records reviewed as part of the AP's yearlong examination of safety issues at aging nuclear power plants. Leaks from at least 37 of those facilities contained concentrations exceeding the federal drinking water standard — sometimes at hundreds of times the limit.
While most leaks have been found within plant boundaries, some have migrated off site, but none is known to have reached public water supplies.
At three sites, two in Illinois and one in Minnesota, leaks have contaminated drinking wells of nearby homes, the records show, but not at levels violating the drinking water standard. At a fourth site in New Jersey, tritium has leaked into an aquifer and a discharge canal feeding picturesque Barnegat Bay off the Atlantic Ocean.
In response to the AP's investigation, two congressmen, Edward J. Markey of Massachusetts and Peter Welsh of Vermont, both Democrats, on Tuesday released a study by independent federal analysts who had identified problems with the regulation of underground piping.
The report by the U.S. Government Accountability Office noted that while the industry has a voluntary initiative to monitor leaks into underground water sources, the NRC hasn't evaluated how promptly that system detects such leaks. "Absent such an assessment, we continue to believe that NRC has no assurance that the Groundwater Protection Initiative will lead to prompt detection of underground piping system leaks as nuclear power plants age," the report's authors concluded.
Any exposure to radioactivity, no matter how slight, boosts cancer risk, according to the National Academy of Sciences. Federal regulators set a limit for how much tritium is allowed in drinking water, where this contaminant poses its main health risk. The U.S. Environmental Protection Agency says tritium should measure no more than 20,000 picocuries per liter in drinking water. The agency estimates seven of 200,000 people who drink such water for decades would develop cancer.
The tritium leaks also have spurred doubts among independent engineers about the reliability of emergency safety systems at the 104 nuclear reactors situated on the 65 sites. That's partly because some of the leaky underground pipes carry water meant to cool a reactor in an emergency shutdown and to prevent a meltdown. Fast-moving, tritium can indicate the presence of more powerful radioactive isotopes, such as cesium-137 and strontium-90.
So far, federal and industry officials say, the tritium leaks pose no health or safety threat. Tony Pietrangelo, chief nuclear officer of the industry's Nuclear Energy Institute, said impacts are "next to zero."
Leaks are prolific
Like rust under a car, corrosion has propagated for decades along the hard-to-reach, wet underbellies of the reactors, generally built in a burst of construction during the 1960s and 1970s.
There were 38 leaks from underground piping between 2000 and 2009, according to an industry document presented at a tritium conference. Nearly two-thirds of the leaks were reported over the past five years.
For example, at the three-unit Browns Ferry complex in Alabama, a valve was mistakenly left open in a storage tank during modifications over the years. When the tank was filled in April 2010, about 1,000 gallons of tritium-laden water poured onto the ground at a concentration of 2 million picocuries per liter. In drinking water, that would be 100 times higher than the EPA health standard.
And in 2008, 7.5 million picocuries per liter leaked from underground piping at Quad Cities in western Illinois — 375 times the EPA limit.
Subsurface water not only rusts underground pipes, it also attacks other buried components, including electrical cables that carry signals to control operations.
A 2008 NRC staff memo reported industry data showing 83 failed cables between 21 and 30 years of service — but only 40 within their first 10 years of service. Underground cabling set in concrete can be extraordinarily difficult to replace.
Under NRC rules, tiny concentrations of tritium and other contaminants are routinely released in monitored increments from nuclear plants; leaks from corroded pipes are not permitted.
The leaks sometimes go undiscovered for years, the AP found. Many of the pipes or tanks have been patched, and contaminated soil and water have been removed in some places. But leaks are often discovered later from other nearby piping, tanks or vaults. Mistakes and defective material have contributed to some leaks. However, corrosion from decades of use and deterioration is the main cause. And, safety engineers said the rash of leaks suggest nuclear operators are hard put to maintain the decades-old systems.
Over the history of the U.S. industry, more than 400 known radioactive leaks of all kinds of substances have occurred, the activist Union of Concerned Scientists reported in September.
Nuclear engineer Bill Corcoran, an industry consultant who has taught NRC personnel how to analyze the cause of accidents, said that since much of the piping is inaccessible and carries cooling water, the worry is if the pipes leak there could be a meltdown.
"Any leak is a problem because you have the leak itself, but it also says something about the piping," said Mario V. Bonaca, a former member of the NRC's Advisory Committee on Reactor Safeguards. "Evidently something has to be done."
Even with the best probes, however, it is hard to pinpoint partial cracks or damage in skinny pipes or bends. The industry tends to inspect piping when it must be dug up for some other reason. Even when leaks are detected, repairs may be postponed for up to two years with the NRC's blessing.
"You got pipes that have been buried underground for 30 or 40 years, and they've never been inspected, and the NRC is looking the other way," said engineer Paul Blanch, who has worked for the industry and later became a whistleblower. "They could have corrosion all over the place."East Coast issues