The Nuclear Regulatory Commission (NRC) recently established a task force to look into releases of water containing tritium into ground water at a half dozen plants over the last decade, including three recently in Illinois, where the state has sued Exelon Corp., for violating state environmental laws because of the releases.

Ground water contamination on plant sites also has been reported at reactors in New York, Connecticut, Florida, California and Arizona, according to the Union of Concerned Scientists, a nuclear industry watchdog group.

Tritium, which can cause cancer with significant exposures, is a normal product of a nuclear reactor. The releases - except for one at Exelon's Braidwood, Ill. reactor - have been kept within plant boundaries. All are reported to have been below the federal health standard of 4 millirems for ground water.

Nevertheless, the releases of tritium-contaminated water into soil at power plants has been of concern to the NRC. Some of the leaks went undetected for as long as 12 years. They generally have occurred because of leaks in pipes or in some cases from the pools in which spent reactor fuel rods are kept.

"The new industry program recognizes that even though radioisotopes have not been detected off site at levels that would jeopardize public health, the industry should adopt a higher standard of excellence in radiation protection that goes beyond what NRC regulations required," says Ralph Andersen, Nuclear Energy Institute's chief health physicist.

"When inadvertent radiological releases in ground water occur at levels that do not require formal reporting, we should inform local and state leaders and the public as a matter of openness and transparency."

Under the new policy, plant operators will establish an action plan "to assure timely detection" of such releases, submit reports to the NRC on ground water samples within plant boundaries and inform state and local officials ground water leaks if they exceed certain levels.

Before the creation of the recent NRC task force, the agency "has been treating the leaks as isolated events. But seven events in 10 years suggests a trend rather than a series of isolated events," says David Lochbaum, director of the nuclear safety project at the Union of Concerned Scientists.