BRATTLEBORO — Two of the state's leading environmental groups have asked U.S. Attorney General Eric Holder to launch a criminal investigation into Entergy Nuclear's admission that it gave false information under oath to state and federal officials.

"We implore you to take all actions necessary to gather information and enforce applicable legal requirements," stated a letter sent to Holder and U.S. Attorney Tristram Coffin of Vermont from the Conservation Law Foundation and the Vermont Public Interest Research Group.

The two groups said Entergy Nuclear had willfully violated federal law and had "carelessly disregarded obligations to maintain and provide accurate information on critical power plant systems."

That carelessness, the two environmental groups said, had led Entergy to operate Vermont Yankee "with careless disregard that has led to contamination of ground and surface waters with radiological substances."

Entergy Nuclear announced Jan. 7 that a monitoring well tested positive for tritium, a radioactive form of hydrogen, and it was launching an effort to find the source of the tritium in underground pipes, which the company last year had repeatedly said didn't exist.

"The public expects that violations will be aggressively pursued. Entergy's conduct should be investigated and appropriately prosecuted," wrote Christopher Kilian of CLF and Paul Burns of VPIRG.

Entergy Nuclear spokesman Larry Smith declined to comment on the CLF-VPIRG letter, but said the company was conducting its own investigation into what prompted company officials to give misinformation to state regulators.

Entergy removed its top executive in Vermont, Jay Thayer, from his position as vice president of operations, and placed him on leave pending the outcome of its own investigation, which is being conducted by an outside law firm.

Thayer apologized for making the false statements to state regulators last year. The issue was whether Vermont Yankee had any underground pipes containing radioactive materials.

The buried pipes have been a source of radioactive leaks at other reactors.

Vermont Attorney General William Sorrell is already conducting an investigation into the Entergy misinformation.

Work on finding Vermont Yankee's tritium leak, which is now in its seventh week, continued Friday, although plant officials are having trouble shoring up a key area they want to excavate, said Bill Irwin, the state's radiological health chief for the Department of Health.

Irwin said levels of tritium in monitoring wells appear to have stabilized, with seven wells showing varying levels of contamination, from a high of just less than 2 million picocuries per liter, to 2,700 picocuries, making it one of the worst tritium contamination cases in the United States, where 27 of 104 commercial nuclear reactors are leaking or have had a tritium leak.

Meanwhile, the Nuclear Regulatory Commission announced Friday that Entergy Nuclear had provided it with a financial guarantee for $40 million, which fills the funding gap the NRC had identified in Vermont Yankee's decommissioning trust fund.

But whether that fund, which is currently pegged at about $420 million, would fund the eventual cleanup of the Vermont Yankee tritium contamination is unknown. Eventual decommissioning costs are expected to be at least double that amount, if not higher, and those estimates were before the tritium leak.

Smith, the Entergy Nuclear spokesman, declined to say how Entergy would be paying for the cleanup, saying it was focusing on finding the leak.

And the NRC's spokesman Neil Sheehan said only that Entergy had to comply with state requirement that it had to return the site to a "green field."

Entergy engineers and technicians continue to focus on a concrete pipe tunnel that continues to have some standing water in it despite it being pumped out earlier.

Irwin said Entergy officials had to drill out the drain since it was plugged.

Irwin said he hoped Entergy would change the underground pipes, and either put them above ground or put them in underground structures that would allow workers to inspect them.

Irwin said there was no way for Entergy to inspect the concrete pipe tunnel that investigators are focusing on without a boroscope, or a tiny camera on a cable.

"I'm beating that drum as much as we can. I don't want to go through this again," Irwin said. He said other nuclear reactors had changed the location of their underground pipes.

"Entergy and VY are looking at the option how to deal with radioactive liquid, and attempting to find a variety of ways so that in the future they do not have to rely on wells," he said.

While the cost of changing the pipes would be significant, Irwin said, so is the investigation into the tritium leak.

Entergy has to make these pipes accessible for periodic inspection, he said.

"I have no idea what it's costing, but it's got to be in the millions of dollars," Irwin said.

susan.smallheer@rutlandherald.com