ST.PAUL, Minn. (AP) — Minnesota regulators said Thursday they are overseeing the cleanup of a 400,000-gallon leak of radioactive water from Xcel Energy’s Monticello nuclear power plant and the company said there was no danger to the public.
“Xcel Energy took swift action to contain the spill to the plant site, which did not pose a risk to the health and safety of the local community or the environment,” the Minneapolis-based company said in a statement.
While Xcel reported the leak of water containing tritium to state and federal authorities in late November, the spill was not made public until Thursday. State officials said they waited to get more information before releasing it publicly.
“We knew there was tritium present in one monitoring well, but Xcel has not yet identified the source of the leak and its location,” Minnesota Pollution Control Agency spokesman Michael Rafferty said.
“Now that we have all the information about where the leak occurred, how much was released into the groundwater and that the contaminated groundwater has moved away from the original location, we are sharing that information,” he said, adding the water residue contained in Xcel’s property and does not pose an immediate risk to public health.
The company said it notified the Federal Nuclear Regulatory Commission and the state on Nov. 22, a day after confirming the leak was coming from a pipe between two buildings. Since then, it has been pumping groundwater, storing and treating the contaminated water, which contains tritium levels below federal thresholds.
“Ongoing monitoring from over two dozen on-site monitoring wells confirms that the leaked water is fully contained on site and has not been detected off-site or in local drinking water,” Xcel Energy said in a statement.
When asked why Xcel Energy did not notify the public earlier, the company said, “We understand the importance of quickly informing the communities we serve if a situation poses an immediate threat to health and safety. In this case, there was no such threat. The company said it was focused on investigating the situation, containing the affected water and figuring out next steps.
The Monticello plant is about 35 miles (55 kilometers) northwest of Minneapolis, upriver from the city on the Mississippi River.
Tritium is a radioactive isotope of hydrogen that occurs naturally in the environment and is a common byproduct of nuclear power plants 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 receive only a low dose, the NRC says.
NRC says there are tritium spills occasionally at nuclear plants, but they have repeatedly been found to either remain confined to plant property or involve off-site levels so low that they do not affect public health or safety. Xcel reported a small tritium leak at Monticello in 2009.
Xcel said it has recovered about 25 percent of the spilled tritium so far, that recovery efforts will continue and that it will install a permanent solution this spring.
“While this spill does not pose a risk to the public or the environment, we are taking this very seriously and are working to address the situation safely,” said Chris Clark, president of Xcel Energy–Minnesota, North Dakota and South Dakota, in a statement. “We continue to collect and treat any potentially affected water while regularly monitoring nearby groundwater sources.”
Xcel Energy is considering building above-ground storage tanks to store the contaminated water it recovers, and is considering options for treating, reusing or ultimately disposing of the collected tritium and water. State regulators will review the options the company chooses, the MPCA said.
Japan is preparing to release a huge amount of treated radioactive waste water into the sea from the triple reactor meltdown 12 years ago at the Fukushima Daiichi nuclear power plant. The water contains tritium and other radioactive contaminants.