A Minnesota nuclear power plant released at least 400,000 gallons of radioactive water in November but the spill was finally made public on Thursday. Regulators in Minnesota informed the public of the development and stated that they had been keeping an eye on the Monticello nuclear facility cleanup, as per a report in the BBC.

Tritium, a typical byproduct of nuclear reactor activities, is present in the water. According to the federal Nuclear Regulatory Commission, tritium is a naturally occurring radioactive isotope of hydrogen that produces a weak type of beta radiation that does not penetrate human skin and does not travel very far in the air (NRC). Tritium spills occasionally happen at nuclear power facilities, although they are typically contained locally and infrequently endanger public safety or health, according to the NRC. Xcel Energy first noticed the leak on November 21 from a conduit between two structures.

The outlet citing Minnesota Department of Health, stated that Minneapolis, the state's largest city, is located roughly 35 miles (56 km) upstream along the Mississippi River from the plan and Mississippi River was not affected by the leak.

"Xcel Energy took swift action to contain the leak to the plant site, which poses no health and safety risk to the local community or the environment," the Minnesota-based utility said in a statement on Thursday.

"Though the Xcel plant is within our community, the City of Monticello does not have the authority to govern the nuclear plant. If state or federal oversight agencies determine that there is any potential or actual impact to the City's drinking water supply or infrastructure, the City will immediately notify the public with assistance from these agencies," Mayor Lloyd Hilgart said in a statement.

Crews checked the plant at all potential leak points, according to Xcel Energy and a lab will be looking at the pipe that leaked. About 25 per cent of the tritium that was spilled has been recovered so far and the company has indicated that it might construct above-ground storage tanks to house the toxic water.