Xcel Energy’s plan to fix leak at Monticello nuclear plant

Xcel Energy announced its plan to take the Monticello Nuclear Generating Plant offline to make permanent repairs after two tritium water leaks were reported.

The plant will slowly start powering down on Friday, which will last over the next couple of days before crews can go in and make repairs. The first leak was reported in November 2022 and released approximately 400,000 gallons of contaminated water. The newest leak was found earlier in the week and is estimated to be in the hundreds of gallons. 

The leak still poses no threat to the safety of drinking water or the environment, said Chris Clark, president of Xcel Energy–Minnesota, North Dakota and South Dakota, during a press conference on Friday. 

What caused the new leak at the Monticello plant

The first leak was detected after a cracked pipe likely led a bi-product of the nuclear reaction process called tritium to leak into the groundwater. Officials put a temporary solution in place to capture the contaminated water and pump it back to be treated at the plant. 

However, over the past couple of days, officials learned the new system was no longer catching all the water and some of it was spilling over and going back into the ground. While the new leak is reportedly much smaller than the first, it was still ongoing as of Thursday night, according to the Minnesota Pollution Control Agency and Minnesota Department of Health.

The leak was reported to state agencies and the Nuclear Regulatory Commission, Clark said. 

The exact cause of the leak is still unknown, but Clark said the pipe was from the plant's original structure, which is 50 years old. 

Xcel Energy's plan to fix the leak 

Over the next few days, Xcel Energy will slowly power down the plant and bring it offline to let it cool before crews go in and make repairs. The workers will cut out the damaged pipe, located between two buildings, and send it out for a complete analysis to see why the pipe failed and make sure it doesn’t happen again. 

It's unknown how much pipe is going to be cut out, but Clark said it's expected to replace the pipe "sufficiently on both sides of the wall."

After the repairs are complete, the plant will undergo a series of inspections to determine if the plant should be brought back online or if they will start the refueling process early, which wasn’t scheduled to begin until April. 

Xcel Energy said the plant being offline should not affect customers’ power as other plants can cover the energy needs. There is no specific timeline for when the plant could return online, but Clark said they can "be out as long as we need to, to what we need to do."

What is the ‘worst case scenario’

It’s "highly unlikely" for the contaminated water to reach the drinking supply, and Clark said it’s "physically impossible" for it to reach some wells as Monticello uses water from upstream the plant and Becker uses water from across the river.  

Clark explained the "worst case scenario" would be for the contaminated water to reach the groundwater and enter into the Mississippi River, but it would dilute so much it would be almost undetectable. The plant is monitoring the river, and it shows there is no leak happening as of right now. 

The plant is also monitoring its own well for drinking water on site and has not detected any tritium. They have a series of monitoring wells around the plant which they are also checking frequently.

Xcel Energy said the leaked water has remained onsite and has not been detected beyond the facility or in any local drinking water. So far, officials say an estimated 32% of the tritium released during the initial leak has been recovered so far.

Is tritium dangerous?

While concerning, tritium is not exceptionally dangerous. It's a very low level of radioactivity and can't penetrate the skin.

The company writes: "Tritium is a compound that is naturally present in the environment and is commonly created in the operation of nuclear power plants. It emits low levels of radiation, similar to everyday materials people use and the food we all eat."