What exactly is tritium? And when is it a health concern?
ST. PAUL, Minn. – Xcel Energy says it has fixed the pipe leak at its nuclear power plant in Monticello and will reopen it soon.
Last fall, at least 400,000 gallons of water containing radioactive tritium leaked from the plant.
The company says it never reached the Mississippi River or contaminated drinking water, and it's cleaned up about one-third of the leak.
But what exactly is tritium? And when is it a health concern?
To understand tritium, WCCO spoke with Zack Mensinger, associate professor of chemistry at Metropolitan State University.
"Tritium, we would not see it directly on the [Periodic Table of Elements]," Mensinger said. "Tritium is an isotope of hydrogen."
Mensinger uses a car as an analogy.
"Hydrogen would be like the model of the car, the tritium would be like, 'Oh, you've added extra features to it,' like you got a sunroof and a fancy stereo system or something like that," he said.
Mensinger says tritium occurs naturally in the environment.
"Incoming cosmic rays can hit nitrogen molecules and then sort of break off pieces of those nitrogen molecules in a way that forms tritium," he said.
Though it can be in a gas, the radioactive element is most commonly found in the form of water. Tritium is also found in many consumer products.
"Things that basically we want to have sort of glow on their own," he said. "Watch dials, things like that that have kind of little pieces of them that will kind of show up at night. Gun sights…exit signs, those kind of all utilize tritium as that source to basically activate those phosphorus to give off that sort of green, luminescent glow."
Nuclear power plants also create tritium as a byproduct of producing nuclear energy. So, how harmful is it to humans?
"Very small amounts, it would probably be very unlikely to be in your body long enough and kind of have enough of it there to do any kind of damage," he said.
According to the Nuclear Regulatory Commission, our annual dose of radiation comes 50% from natural radiation from the outdoors and sun; 48% from medical procedures; 2% from products or air travel; and less than 1% from nuclear power generation.
"Sometimes these radioactive elements can sort of go through one decay process and actually decay into something else that is radioactive," he said. "But in this case, tritium pretty quickly is going to decompose into things that are not super harmful or concerning."
The Minnesota Department of Health says tritium can't travel far by air, and it's too weak to go through skin. So exposure is more likely from swallowing contaminated water.
However, there is no evidence the Monticello leak has reached private wells or public drinking water.
