Water containing radioactive material has leaked twice from a nuclear plant near Minneapolis and the plant will be shut down, but there is no danger to the public, the plant’s owner said Thursday.
A leak of what is believed to be hundreds of gallons of water containing tritium was discovered this week from a temporary repair at the Monticello Nuclear Generating Plant, where 400,000 gallons (1.5 million liters) of water with tritium leaked in November, Xcel Energy said in a statement on Friday.
The plant about 38 miles (61 kilometers) northwest of Minneapolis is scheduled to shut down Friday so permanent repairs can begin, the company said.
There was a months-long delay in disclosing the initial leak that raised questions about security and public transparency, but industry experts said there was no public health threat.
The new leak, which was announced a day after Xcel Energy said it had been discovered, was traced to a temporary repair to the original leak, the company said in a statement. This time, the leak is anticipated to be hundreds of gallons.
“While the leak continues to pose no risk to the public or the environment, we determined the best course of action was to shut down the plant and immediately make permanent repairs,” said Chris Clark, president of Xcel Energy–Minnesota, North Dakota. and South Dakota. “We continue to work with and inform state, federal, city and county leaders in the process.”
After the leak was first discovered in November, Xcel Energy made short-term fixes to retrieve water from the leaky pipes and redirect it to the plant for reuse. This solution is designed to prevent new tritium from reaching the groundwater until the installation of replacement pipes during the regularly scheduled outage in mid-April, the company said.
However, monitoring equipment showed Wednesday that a small amount of new water from the original leak had reached the groundwater. The operator discovered that, over the past two days, the temporary solution was unable to capture all of the leaking water, Xcel Energy said.
The leaked water remains at the site and has not been detected in local drinking water, Xcel Energy said.
Tritium is a radioactive isotope of hydrogen that occurs naturally in the environment and is a common byproduct of nuclear plant operations. It emits a weak form of beta radiation that does not travel far and cannot penetrate human skin, according to the Nuclear Regulatory Commission.
The Minnesota Pollution Control Agency and the Minnesota Department of Health released a statement Thursday saying they were notified of the new leak Thursday afternoon and it is still ongoing. The agency said it will continue to monitor groundwater samples and will notify the public if there is an imminent risk.
Minnesota regulators said last week that Xcel Energy voluntarily told state agencies and reported the tritium leak to the Nuclear Regulatory Commission after it was confirmed in November. The amount of leaked material never reached the threshold that required public notification and a public announcement is pending until more information is available, officials said.
Edwin Lyman, director of nuclear power safety with the Union of Concerned Scientists, told The Associated Press last week that significant health risks would only occur if people used high enough tritium. That risk exists if the plume remains on the company’s site, Xcel Energy and Minnesota officials said.