Minnesota nuclear power plant to shut down Friday to repair leak of water containing radioactive compound

By Aya Elamroussi and Andy Rose, CNN

Roughly four months after a nuclear power plant in central Minnesota experienced a water leak containing a radioactive compound, the operator said it will shut down the facility beginning Friday to conduct repairs of a new leak “immediately.”

The operator of the plant, Xcel Energy, said in a news release Thursday that the leak — near the Mississippi River — is confined to the facility.

Monitoring equipment determined earlier this week that a small amount of the leaking water has begun reaching groundwater at the site, the operator said, which comes a few months after about 400,000 gallons were released in an initial leak.

“While the leak continues to pose no risk to the public or the environment, we determined the best course of action is to power down the plant and perform the permanent repairs immediately,” said Chris Clark, president of Xcel Energy-Minnesota, North Dakota and South Dakota.

The shutdown is not expected to impact electrical service in the area, the company said.

The earlier radioactive compound leak was confirmed and reported to state and federal officials in late November 2022, according to a mid-March news release from the operator. The leak was “fully contained on-site,” the release said.

That initial leak consisted of about 400,000 gallons of water containing tritium, according to the Minnesota Pollution Control Agency. Tritium is a chemical compound that emits low levels of radiation and breaks down more quickly than many other radioactive materials.

On Thursday, Xcel Energy notified the state Pollution Control Agency of a new water leak near the same spot of the previous leak, which the agency said is a much smaller amount in the hundreds of gallons.

“State agencies have no evidence at this point to indicate a current or imminent risk to the public and will continue to monitor groundwater samples. Should an imminent risk arise, we will inform the public promptly,” the state agency said.

The plant’s shutdown comes about three months after Xcel Energy submitted an application to the US Nuclear Regulatory Commission to renew its operating license for the Monticello facility.

Valerie Myers, a senior health physicist with the US Nuclear Regulatory Commission and part of the federal team tasked with monitoring the cleanup, attended a public hearing held for residents to speak on the license renewal, CNN affiliate WCCO reported Wednesday.

Myers explained that there is three times as much tritium in a hallway exit sign than in the water under the Xcel Energy nuclear power plant, the outlet reported.

“If we look at the dose impact of something like this, it would be a fraction of a milligram. I’m talking 0.00-something milligrams. The average person will get 300 milligram in a year just from the sun, the ground, everything,” Myers told WCCO.

However, Myers indicated that the groundwater is being monitored due to the plant’s proximity to the Mississippi River.

“There are wells between the ones that are showing elevated tritium, and the Mississippi that are not showing any elevated levels. We are watching that because the ground flow is toward the Mississippi,” Myers said.

Tritium occurs naturally in the environment at extremely low concentrations, and people are generally exposed to it daily in small amounts, according to the US Environmental Protection Agency. It can enter the body when people swallow water containing the isotope, “inhale tritium as a gas in the air, or absorb it through their skin,” the agency states in an online explainer.

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