VERNON — Vermont Yankee's plan to send radioactive wastewater cross-country to Idaho “will not have a significant effect on the quality of the human environment,” federal regulators have decided.
The U.S. Nuclear Regulatory Commission hasn't yet given the official green light for 200,000 gallons of water to be trucked from the Vernon plant to US Ecology's disposal facility near Grand View, Idaho.
But the NRC's environmental findings, announced April 3, show that the federal agency is now comfortable with Entergy's assurances that the shipments wouldn't pose radiological or nonradiological problems.
“Our evaluations show there would be minimal risk from the shipment and disposal of the water,” NRC spokesman Neil Sheehan said.
The December 2014 shutdown of Vermont Yankee left Entergy with two kinds of contaminated water.
There's “process” water, which is liquid drained from plant systems. And there's also “intrusion” water, which is groundwater that's been infiltrating the plant's turbine building at greater-than-expected rates.
Both types of water are contaminated with low levels of radioactivity.
Water-intrusion issues
Entergy had been expecting to deal with process water, but the intrusion problem first came to light in early 2016. At one point, flows were so high - as much as 2,500 to 3,000 gallons daily - that Entergy used open swimming pools and industrial bladders as temporary storage.
The pools are long gone. Entergy has worked to reduce the intrusion rate and also has been shipping water out of state via a contractor named EnergySolutions, which uses a disposal site in Tennessee.
“Generally speaking, we're shipping about one or two shipments per week, depending on how much we have in storage,” Joe Lynch, Entergy Vermont Yankee government affairs manager, said during a March 23 meeting in Brattleboro.
At that same meeting, Lynch said Vermont Yankee had shipped a total of 493,000 gallons of groundwater.
While EnergySolutions has been handling all of those shipments to date, Vermont Yankee administrators have been trying to formulate a backup disposal plan. Hence the NRC application for US Ecology in Idaho.
“Although not currently needed, we desire to have US Ecology as a contingency water-disposal option,” Lynch said in an April 4 email.
Entergy has no plans to send intrusion water to Idaho. Instead, the site is seen as a potential destination for approximately 200,000 gallons of radioactive process water that is currently stored at Vermont Yankee in a large tank called the torus.
The federal notice says that water would be transported by truck in 40 shipments, each consisting of 5,000 gallons. Upon arrival at US Ecology, the wastewater “will be solidified with clay and disposed as a soil-like waste.”
NRC officials are considering two matters related to the Idaho proposal - Entergy's pitch for an alternate disposal site, and US Ecology's request to accept the water. The latter request is necessary because the Idaho facility isn't currently licensed by the NRC.
There have been some questions raised about the plan.
'No significant impact'
NRC documents show that, while Idaho officials didn't comment on the matter, Vermont officials asked questions about radioactivity levels, projected impacts on truck drivers, and other issues.
The NRC asked similar questions last year, citing “uncertainty in the concentration of radionuclides in the water.”
But Sheehan said Entergy has answered those questions to the NRC's satisfaction, leading to the finding of “no significant impact.”
The NRC cites a number of factors in that decision, including:
• The US Ecology site has “natural and engineered features that limit the release of any stored radioactive material into the environment,” officials wrote.
Those include low annual precipitation rates; a “long average vertical distance” to reach groundwater; and landfill features including a cover, liners, and a monitoring system.
• Projected radioactivity doses to truck drivers and US Ecology workers will meet NRC requirements of “not more than a few” millirems per year, officials found.
To put that into perspective, Sheehan said the annual exposure limit for nuclear plant workers is 5,000 millirems. He added that an “average American is exposed to about 680 millirems of radiation each year from natural and manmade sources.”
Officials have said that the contaminated water at Vermont Yankee contains very low levels of radioactivity - so low that the trucks carrying it don't have to be marked with special placards.
• The NRC also determined that there would be no significant nonradiological impacts from the water shipments. That includes “no effect on endangered or threatened species or their critical habitat.”
If Vermont officials have any more questions about nonradiological contaminants in the water, they'll have to take those up separately with Vermont Yankee, the NRC added.