U.S. nuclear power plant operators haven’t figured out how to quickly detect leaks of radioactive water from aging pipes that snake underneath the sites — and the leaks, often undetected for years, are not going to stop, according to a new report by congressional investigators.

The report by the Government Accountability Office was released by two congressmen Tuesday in response to an Associated Press investigation that shows three-quarters of America’s 65 nuclear plant sites have leaked radioactive tritium, sometimes into groundwater.

Separately, two senators asked the GAO, the auditing and watchdog arm of Congress, to investigate the findings of the ongoing AP series Aging Nukes, which concludes that the U.S. Nuclear Regulatory Commission and the nuclear power industry have worked closely to keep old reactors operating within safety standards by weakening them, or not enforcing the rules.

A third senator, independent Bernie Sanders of Vermont, said the AP series has raised disturbing allegations about safety at aging plants and reiterated his demand that the Vermont Yankee plant be shut.

In the report released Tuesday by Democratic Reps. Edward J. Markey of Massachusetts and Peter Welch of Vermont, the GAO concluded that while a voluntary initiative that industry recently adopted is supposed to identify leaks, the U.S. Nuclear Regulatory Commission doesn’t know how fast problems are detected.

“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.

No leak is known to have reached aquifers that hold the drinking water supplies of public utilities, though tritium, a radioactive form of hydrogen, has contaminated residential drinking wells near at least three nuclear power plants. The tritium in those wells did not surpass the federal health standard. Though mildly radioactive, tritium poses the greatest risk of causing cancer when it ends up in drinking water.

Markey’s spokeswoman said his office received the GAO report in early June after requesting it in 2009 following reports of a tritium leak at the Indian Point nuclear plant north of New York City. Typically congressional offices hold reports for 30 days, but Markey released it in response AP’s tritium story, part of an ongoing investigative series.

In a written statement, he compared the ongoing nuclear crisis at Japan’s Fukushima Dai-ichi plant to the kind of meltdown he said could happen in the U.S. if a pipe that is supposed to carry water to cool a reactor’s core fails.

“There would be no warning because no one ever checks the integrity of these underground pipes,” Markey said.

The industry’s Nuclear Energy Institute cited its “underground piping integrity initiative policy,” launched voluntarily in 2009, as proof that it takes tritium leaks seriously.

“The initiative commits the industry to a series of actions to establish more frequent inspection and enhance dependability of underground piping with a goal of protecting structural integrity and preventing leaks,” the institute said in a statement.

The institute also criticized AP’s overall findings and “selective, misleading reporting in a series of new articles on U.S. nuclear power plant safety.”

Previously, the AP reported that regulators and industry have weakened safety standards for decades to keep the nation’s commercial nuclear reactors operating. While NRC officials and plant operators argue that safety margins can be eased without compromising safety, critics say these accommodations are inching the reactors closer to an accident.

In response to those findings, New Jersey’s two Democratic senators asked the GAO for a new investigation based on “the serious allegations” documented by the AP.

“It would be of grave concern to us if, in fact, aging power stations have achieved compliance with operating rules because of weakened NRC rules, rather than demonstrated compliance with existing standards,” Sens. Frank R. Lautenberg and Robert Menendez wrote.

Posted 6/22/2011