400,000 gallons of water contaminated with radioactive tritium leaked from Monticello nuclear power plant

Tritium is a radioactive gas or liquid derived from hydrogen that is a byproduct of producing electricity at nuclear power plants, according to Mark Smith, an environmental specialist with the MPCA.

Tritium leaks at nuclear power plants do not seem to be rare. A 2012 investigation by the Associated Press found that tritium at the time had leaked at 48 of the nation's 65 nuclear power plants. All of the leaks had been contained on plant sites with none of the leaks known to reach public water supplies, according to the Associated Press.

Tritium is extremely rare in its natural form as a radioactive form of hydrogen, but can be found in trace amounts in the atmosphere.

A plume of tritium-contaminated water is located in the groundwater on the nuclear power plant property. There is no eminent danger to the environment or drinking water supply in the region, according to Chris Clark, president of Xcel Energy–Minnesota, North Dakota, and South Dakota.

Neither the nearby Mississippi River nor a well providing water to nuclear power plant employees has been negatively impacted by the leak, Clark said.

Clark explained that about 400,000 gallons of water containing radioactive tritium leaked from a water pipe running between two buildings at the Monticello facility.

Since the leak was first detected in November, about 150,000 gallons of contaminated water has been recovered from the groundwater supply and is being contained in a series of 20,000 gallon vessels, the MPCA's Smith said.

Known as frac tanks, the recovery tanks resemble shipping containers utilized in the rail industry, added Pat Flowers, manager of environmental services with Xcel Energy.

Xcel Energy officials stated it could take up to a year to recover the entire 400,000 of contaminated water.

That recovery is being accomplished by pumping the contaminated groundwater through extraction wells and into the storage containers, according to the MPCA, which has actively been reviewing data, including well sampling results provided by Xcel Energy, and overseeing remediation efforts at the Monticello plant.

“Our top priority is protecting residents and the environment, and the MPCA is working closely with other state agencies to oversee Xcel Energy’s monitoring data and cleanup activities,” said Kirk Koudelka, MPCA assistant commissioner for land and strategic initiatives. “We are working to ensure this cleanup is concluded as thoroughly as possible with minimal or no risk to drinking water supplies.”  

Xcel Energy's Clark reiterated that there is no public health risk associated with the leak.  Tritium cannot permeate the skin and is harmful only if taken internally by drinking very large amounts of contaminated water.

The MPCA's Smith said his agency takes public health and environmental safety very seriously and went public with news of the tritium leak because after three months Xcel Energy and state agencies now had the data in hand to share the broader story.

"We want to make sure the folks out there have the complete information, the MPCA's Koudelka added.

 Xcel Energy President Clark added that the MPCA and City of Monticello officials encouraged the utility company to be fully transparent and share details of the leak as well, even though the water in question is contained on its property.

The bottom line, Clark said, is that "We put something in the ground and want to be sure we get it back up."

With the biannual outage coming to the Monticello plant in mid-April, Xcel Energy is exploring building above-ground storage tanks or installing a retention pond to store water containing tritium that has been collected during ongoing recovery activities.

The company is also considering options for treatment, reuse, or final disposal of the collected tritium and water. Minnesota state agencies will review any options selected by Xcel Energy.

During outage, Xcel Energy will also take a sample of the pipe that leaked and send it off for testing, Clark said.

"We will make sure this doesn't happen again in the future," Clark said.