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Xcel Energy says it discovered low levels of radioactive tritium in two more monitoring wells near the Mississippi River in Monticello, although not in the river itself.

The utility has been working to recover tritium from as much as 900,000 gallons of contaminated water that leaked into the ground at its Monticello nuclear plant more than two years ago.

The tritium levels in both monitoring wells are below the U.S. Environmental Protection Agency's limit for safe drinking water, which is 20,000 picocuries per liter.

In response, Xcel said it's adjusting the amount it pumps to help control the flow of groundwater and recover it more effectively. 

Tritium is a naturally occurring radioactive form of hydrogen that is produced in the atmosphere. It is also a byproduct of producing electricity from nuclear power plants. 

A relatively weak source of radiation, tritium emits beta particles at such a low level they are unable to penetrate human skin. It can be hazardous, but only if it’s ingested in large quantities.

The utility says it has reduced tritium concentrations by more than 90 percent since the initial spill. Of more than three dozen monitoring wells on the site, two directly below the plant currently measure tritium above the EPA standard. 

“We remain committed to being good neighbors and stewards of the environment, as well as following all regulations, as we continue the cleanup,” the company stated.

State health officials have said the tritium has not posed a risk to the surrounding communities or the environment.

Xcel said the groundwater pumping will not affect the plant’s regularly scheduled outage for refueling, which begins Friday.

Kirsti Marohn

Author

The utility has been working to recover radioactive tritium from as much as 900,000 gallons of contaminated water that leaked into the ground at its Monticello nuclear plant more than two years ago. The tritium levels in both monitoring wells are below the U.S. Environmental Protection Agency's limit for safe drinking water. 

Electrical lines and towers frame a power plant

Tritium found in two more monitoring wells near Monticello nuclear plant

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