A plant in Minnesota announced that tritium water had spilled after applying for a permit renewal
Authorities in the northern US state of Minnesota revealed on Thursday that a nuclear power plant near Minneapolis suffered a radioactive spill of more than 1.5 million gallons of water. Xcel Energy, owner of the Monticello nuclear power plant, is working to clean up the spill and insists there is no danger to the general public.
The Minnesota Pollution Control Agency (MPCA) said about 400,000 gallons of tritiated water leaked from a broken pipe at the facility. The leak was first reported on November 22, and the source was found and patched on December 19 “soon after.”
Xcel Energy and the state are “active management” the situation to prevent the underground plume of irradiated water from spreading to the nearby Mississippi River, MPCA Assistant Commissioner Kirk Koudelka told the Minneapolis Star-Tribune.
“This does not pose a public health or drinking water problem”, said Christopher Clark, the president of Xcel for Minnesota. He admitted that it is tritiated water “well above” the 20,000 picocuries standard mandated by the Environmental Protection Agency (EPA), being “in the millions” directly under the plant.
The city of Monticello issued a statement saying drinking water supplies were not affected by the leak, which occurred outside of the area where they extract groundwater for municipal wells.
The contaminated water has not been detected outside the perimeter of the plant, Xcel told KMSP-TV. An estimated 25% of the water was collected and pumped into a treatment system on site. The company is considering building storage tanks or a retention pond for the project, which could take a year or more.
Viktoria Mitlyng, a spokeswoman for the US Nuclear Regulatory Commission (NRC), said the leak was well below the NRC safety threshold and that the plan did not violate regulations. Tritium leaks “are not unusual for nuclear power plants,” she added.
The Monticello plant had a leak of about 2,000 gallons (7,500 liters) in 1981, with some of the water reaching the river, but health officials said it posed no danger to wildlife or public health.

In January, Xcel sent an application to the NRC to extend Monticello’s license for another 20 years beyond 2030, when the current license expires. The company said the extension was “criticism” to comply with Minnesota’s new law mandating 100% carbon-free electricity by 2040.
Tritium is one “mild” radioactive isotope of hydrogen, commonly found in water used to cool nuclear reactors. The only way it can affect people is if they breathe it in or drink tritiated water, said Daniel Huff, an assistant commissioner with the Minnesota Department of Health, adding that the public’s exposure to a nuclear power plant “should be zero.”
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