Utility Shuts Down Minnesota Nuclear Plant Over Radioactive Leak

Radioactive water leaks from plant for 2nd time in recent days

Cooling towers release heat generated by boiling water reactors at Xcel Energy's Nuclear Generating Plant in Monticello, Minn., on Oct. 2, 2019. Evan Frost/Minnesota Public Radio via AP

A utility company said it will shut down its nuclear power plant in Minnesota after it found a radioactive substance that’s being leaked into nearby groundwater.

Xcel Energy confirmed Thursday it will start the shutdown of the Monticello power plant on Friday to perform repairs to “permanently resolve a leak of water containing tritium at the plant,” according to a news release. The firm said that no disruptions will be made to customer service.

“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,” claimed Chris Clark, president of Xcel Energy, in a statement. “We are continuing to work with and inform our state, federal, city and county leaders in the process.”

Earlier this month, Minnesota regulators said they are monitoring the cleanup of a leak of 400,000 gallons of radioactive water from the Monticello facility. At the time, Xcel said there was no danger to the public.

While Xcel reported the leak of water containing tritium to state and federal authorities in late November, the spill had not been made public before this month. State officials said they waited to get more information before going public with it.

In a statement in mid-March, the Minnesota Pollution Control Agency said it was working with other state agencies to “to ensure this cleanup is concluded as thoroughly as possible with minimal or no risk to drinking water supplies.” After the 400,000 gallons leaked, it was stopped by the company, the agency said, adding that it is now ”monitoring the groundwater plume through two dozen wells.”

The company said it notified the federal Nuclear Regulatory Commission (NRC) and the state on Nov. 22, the day after it confirmed the leak, which came from a pipe between two buildings. Since then, it has been pumping groundwater, storing and processing the contaminated water, which contains tritium levels below federal thresholds.

“After identifying the source of the leak late last year, which poses no health and safety risk to the local community or the environment, Xcel Energy implemented a short-term solution to capture water from the leaking pipe and reroute it back into the plant for re-use,” said the company in the Thursday news release. “This solution was originally designed to prevent any new tritium from reaching the groundwater until the company could install a replacement pipe during a regularly scheduled refueling outage in mid-April.”

The Monticello plant is about 35 miles northwest of Minneapolis, upstream from the city on the Mississippi River.

Tritium is a radioactive isotope of hydrogen that occurs naturally in the environment and is a common by-product of nuclear plant operations. It emits a weak form of beta radiation that does not travel very far and cannot penetrate human skin, according to the NRC. A person who drank water from a spill would get only a low dose, the NRC says.

A page on the NRC’s website suggests that tritium has been leaked at U.S. nuclear power plants over the years. But it stipulated that nuclear plants usually limit the radioactive substance on the plant’s property or are involved in such low levels that they don’t affect public safety.

“Ongoing monitoring from over two dozen on-site monitoring wells confirms that the leaked water remains fully contained on-site and has not been detected beyond the facility or in any local drinking water,” said Xcel on Thursday. “State agencies continue to monitor Xcel Energy’s remediation work to ensure the continued safety of the local community and surrounding environment. To date, Xcel Energy has recovered about 32 percent of the tritium released and will continue recovery over the course of the next year.”

It’s not clear when the Minnesota power plant will come back online for operations. Officials said that a “schedule for resuming operation at the plant is still to be determined” and that the plant will start its refueling process this spring.

Meanwhile, Japanese government officials recently announced a plan to release a large quantity of treated radioactive water into the ocean from the reactor meltdowns at the Fukushima power plant more than a decade ago following the March 11, 2011, earthquake. That radioactive water also contains tritium, according to reports.

The Associated Press contributed to this report.