VERNON — The Intex Easy Set swimming pool retails for anywhere from $35 to $500 depending on its dimensions, and it's advertised as one of “the easiest family and friend-sized pools to set up in the world.”
But in Vernon, the Easy Set is serving a much different purpose: to help manage a complex groundwater-intrusion problem at Vermont Yankee.
Photos of the plant's interior show several blue pools marked with yellow radioactive warnings due to the full load of contaminated water inside. Pumps and hoses are connected to the pools in some images; others show nearby large inflatable bladders apparently filled with water.
The images were submitted to VTDigger.org, the nonprofit state journalism website with which The Commons collaborates on Vermont Yankee coverage.
While the setup might appear haphazard, Nuclear Regulatory Commission spokesman Neil Sheehan expressed confidence that the contaminated liquid is being handled safely while plant owner Entergy develops a longer-term plan for managing radioactive water there.
“The pools are located in the lower level of the turbine building and placed such that any leakage would drain into the plant's radioactive waste-treatment system,” Sheehan said. “Also, the company has moved to using more robust bladders to hold the water.”
“The pools filled with this low-level [radioactivity] do not pose a threat to public health because of their location inside the secured building,” Sheehan continued.
Entergy Nuclear Vermont Yankee spokesman Marty Cohn echoed those remarks, saying that “there is no health or safety impact to the public or employees from this issue.” The swimming pools are a temporary measure, he added.
“The integrity of the pools was found to be adequate and the water found to be acceptable for those types of pools,” Cohn said. “Drains near these pools lead to sump pumps, which in turn lead to a waste-processing system.”
Groundwater in the turbine building
Vermont Yankee stopped power production in December 2014, and the NRC last year removed its resident inspector from the site. But the federal agency has continued periodic inspections, and the groundwater issue first surfaced in the NRC's fourth-quarter report released in January.
That document notes that “radioactive water inventories were increasing due mainly to the intrusion of groundwater.” Officials wrote that Entergy had been considering options both to stem the flow of groundwater and to eventually dispose of it.
After the inspection report was released, Sheehan said the problem is occurring on the lowest level of the plant's turbine building. Groundwater intrusion has been averaging a few hundred gallons daily, Sheehan said, but there had been “occasional spikes” that on one day rose to 1,500 gallons.
Entergy has a water-management plan and has been pumping and storing groundwater, which is considered contaminated due to its contact with the building. By early February, 90,000 gallons had been collected.
Groundwater intrusion was anticipated and in some ways is a symptom of the plant's shutdown, since heat from power generation prior to shutdown had caused some of the liquid to evaporate.
But officials said they had not expected so much water to arrive so quickly.
Entergy, according the the NRC, has taken steps, including hiring a contractor to seal cracks and drilling “interceptor wells” to capture and pump out the water.
Photos from inside the building show additional methods for storing the collected liquid.
Sheehan said the large bladders are standard procedure for storing contaminated water. “The bladders - these heavy, rubberized-material containers - are used at many plants,” he said. “So that's an acceptable storage method.”
The pools, on the other hand, are meant as a short-term stopgap while Entergy attempts to address the issue, Sheehan said.
“The water in the pools has very low levels of tritium, not much above the [federal] limit for drinking water - though, of course, this water is not being used for drinking-water purposes,” Sheehan said.
There is a history of tritium problems at Vermont Yankee, though officials say the problem has decreased over the past several years.
In late 2009, elevated levels of tritium were detected in the groundwater at Vermont Yankee, the consequence of a leak from an underground pipe, despite the insistence of plant officials under oath in state Public Service Board proceedings that such a pipe did not exist.
The concentration of tritium then was 2,500,000 picocuries per liter, much higher than the concentration of the VY groundwater now.
Tritium, a colorless, odorless gas, is a radioactive isotope of hydrogen. The isotope, a byproduct of nuclear power generation, also occurs naturally, binding with oxygen to create its most common form: tritiated water.
In December, the NRC reported that 46 of 65 past or present nuclear plant sites in the United States have elevated levels of tritium. The report measured the concentration of tritium at Vermont Yankee at 19,000 picocuries per liter. Officials said the federal limit for safe drinking water is 20,000 picocuries of tritium per liter.
Officials say there is no evidence that the tritiated groundwater seeping into the turbine building is a threat to drinking-water supplies.
As for safety within the plant, photos also show several types of signs bearing contamination warnings in the water-containment area.
“[Plant workers] are trained in dealing with such material, including approaches to limiting exposure, and the areas must be properly marked,” Sheehan said.
What to do with the water?
Regardless of any short-term storage solutions, Entergy must come up with a plan for getting radioactive water off the property eventually.
And that plan stretches beyond the groundwater issue, as the NRC has said there are more than 1 million gallons of water at Vermont Yankee, including liquid storied in a large, doughnut-shaped reservoir at the base of the reactor building.
Entergy has requested NRC approval to ship about 200,000 gallons of radioactive water to Idaho for disposal. There also has been preliminary talk of possible discharges into the Connecticut River, though any such plan would come under intense scrutiny by state regulators.
Sheehan said the NRC is still “awaiting additional information from Entergy on its broader plans for addressing radioactive water at the site.”
In the meantime, the agency is continuing to monitor the situation. Sheehan said an NRC inspector last visited Vermont Yankee in early February, and “he did review work in progress to mitigate the inflow of groundwater into the turbine building.”
Groundwater contamination at Vermont Yankee also is monitored by the Vermont Department of Health. Bill Irwin, the department's radiological and toxicological sciences chief, said he has requested a meeting with Entergy administrators regarding the groundwater-intrusion issue.
But Irwin added that the state does not have jurisdiction in this matter.
“The management of water within the plant is an Entergy VY and NRC issue,” Irwin said. “The Health Department's particular interest is, though, when water from the plant moves from inside the structures, systems, and components into the environment for potential impacts on the public.”