: A US nuclear plant leaked 1,514,164 litres of radioactive water through a broken pipe, raising fears that the liquid had seeped into the ground.

Xcel Energy, which operates the facility northwest of Minneapolis, said the leak of water containing tritium occurred in November, but did not explain why it waited more than three months to publicly acknowledge what had happened.

The company said it notified state officials and the federal Nuclear Regulatory Commission (NRC) when it learned of the leak on November 22, but it was not announced until this week.

Tritium is a radioactive isotope of hydrogen that is a by-product of the production of electricity at nuclear plants. It can also occur naturally.

“While this leak does not pose a risk to the public or the environment, we take this very seriously and are working to safely address the situation,” Chris Clark, the utility’s president, said in a statement.

The Minnesota Pollution Control Agency said none of the water had “reached the Mississippi river or contaminated drinking water sources”. State officials “are actively reviewing data” from the site and “overseeing remediation efforts,” the agency said.

The company said it had “recovered about 25 per cent of the tritium released and will continue recovery over the course of the year”.

The leak originated in “a water pipe between two buildings” at the Monticello nuclear plant, 63km northwest of Minneapolis, the state’s largest city, where Xcel Energy has its headquarters.

The spill was detected during routine groundwater testing and contained by diverting it to an in-plant treatment facility.

Xcel will build “large tanks to store the recovered water until it can be treated and reused,” the company said.

The Daily Telegraph, London