US regulators monitor tritium leak at Minnesota nuclear plant

Minnesota regulators have said that they're monitoring the cleanup of a leak of 400,000 gallons of radioactive water from Xcel Energy's Monticello nuclear power plant, and the company said there's no danger to the public. The leak was first detected in November of last year.

"Xcel Energy took swift action to contain the leak to the plant site, which poses no health and safety risk to the local community or the environment," the Minneapolis-based utility said in a statement, according to CBS News.

While Xcel reported the leak of water containing tritium to state and federal authorities in late November, the spill had not been made public before March 16.

"If at any point there had been a concern for the public safety, we would of course, immediately have provided more information," Chris Clark, president of Xcel Energy-Minnesota, North Dakota and South Dakota, told CBS Minnesota on March 16. "But we also wanted to make sure we fully understood what was going on before we started raising any concerns with the public around us."

State officials said they waited to get more information before going public with it.

"We knew there was a presence of tritium in one monitoring well, however, Xcel had not yet identified the source of the leak and its location," Minnesota Pollution Control Agency spokesman Michael Rafferty said.

"Now that we have all the information about where the leak occurred, how much was released into groundwater, and that contaminated groundwater had moved beyond the original location, we are sharing this information," he said, adding the water remains contained on Xcel's property and poses no immediate public health risk.

The Minnesota Department of Health also stated on its website that the leak did not reach the Mississippi River.

Tritium is a radioactive isotope of hydrogen that occurs naturally in the environment and is a common by-product of nuclear plant operations. It emits a weak form of beta radiation that does not travel very far and cannot penetrate human skin, according to the NRC [National Regulatory Commission]. A person who drank water from a spill would get only a low dose, the NRC says.

The NRC says tritium spills happen from time to time at nuclear plants, but that it has repeatedly determined that they've either remained limited to the plant property or involved such low offsite levels that they didn't affect public health or safety. Xcel reported a small tritium leak at Monticello in 2009.

Xcel said it has recovered about 25 per cent of the spilled tritium so far, that recovery efforts will continue and that it will install a permanent solution this spring.