Tritium is a naturally occurring radioactive form of hydrogen that is produced in the atmosphere. It is a byproduct of the production of electricity by nuclear power plants.
Xcel Energy said the leak came from a water pipe running between two buildings at its Monticello facility and was stopped.
The company also said it is monitoring the groundwater plume through two dozen wells while pumping contaminated groundwater through extraction wells.
“We are working to ensure this cleanup is concluded as thoroughly as possible with minimal or no risk to drinking water supplies,” said Kirk Koudelka, MPCA assistant commissioner for land and strategic initiatives.
Xcel Energy is said to be exploring building aboveground storage tanks or installing a retention pond to store water containing tritium that has been collected during ongoing recovery activities.