VERNON—Since February, Vermont Yankee has shipped away nearly 400,000 gallons of polluted water via tanker truck.
But those trucks aren’t departing from the shut-down Vernon nuclear plant nearly as often as they had been earlier this year.
That’s because plant administrators say they’ve continued to attack a stubborn water-intrusion problem in the facility’s turbine building. In fact, they say the most recent water-control measure reduced flows by about half.
“That’s a success, and we continue to look at other areas that we can seal up or repair to continue to minimize that intrusion water,” said Joe Lynch, government affairs senior manager for plant owner Entergy.
The water issue first emerged in February as part of a routine inspection report issued by the federal Nuclear Regulatory Commission.
Vermont Yankee administrators said they had expected some groundwater to seep into the lower level of the dormant plant’s turbine building. But they hadn’t planned for so much, so fast — as evidenced by the fact that the radioactive water was for a short time stored in swimming pools.
Those pools soon were replaced by a more robust system utilizing industrial bladders and tanks. And Entergy contracted with Utah-based EnergySolutions to dispose of the liquid, which contains low levels of tritium due to contact with the turbine building.
At one point, EnergySolutions was taking four 5,000-gallon shipments a week from Vermont Yankee. A Dec. 1 Entergy report showed that 394,000 gallons of intrusion water had been shipped so far — the equivalent of about 79 truckloads.
But now, with the water problem easing, EnergySolutions is handling only three shipments per month. The water continues to go to a disposal facility in Tennessee, Lynch said.
Vermont Yankee has solicited help from consultants and hydrogeologists to slow the flow. A spokesman has said one solution simply was to seal “a number of cracks” in the turbine building.
A few months ago, administrators turned their attention to restoring an underground barrier between the turbine and reactor buildings. Lynch said that has pushed water-intrusion rates down to 400 to 500 gallons a day, a big decrease from 900 to 1,000 gallons a day prior to the project.
When the problem was at its worst, Entergy reported seeing water influxes as high as 2,500 to 3,000 gallons daily.
The NRC has endorsed Entergy’s handling of polluted water in Vernon. And state officials have said the plant’s water woes led to stronger lines of communication with Entergy.
At this point, Vermont Yankee needs only one storage tank for tainted water. Lynch said that tank has been winterized “so we can accept water and ship water during the winter months.”
That’s an indication, however, that the problem isn’t going away entirely anytime soon.
“We have implemented several projects producing significant reductions in water intrusion and will continue to identify and assess opportunities to reduce groundwater intrusion,” Vermont Yankee spokesman Marty Cohn said Monday.
Water issues aside, Lynch said Vermont Yankee’s “big focus” is still on construction of a second pad for spent fuel storage. That work is “on schedule or ahead of schedule,” he told the Vermont Nuclear Decommissioning Citizens Advisory Panel at a Dec. 1 meeting.
Most of Vermont Yankee’s radioactive spent fuel remains in a cooling pool inside the plant’s reactor building. As a condition of the proposed sale of the plant to NorthStar Group Services, Entergy now is pledging to move all of that fuel into sealed casks by the end of 2018.
That fuel move is a $143 million undertaking contracted to Florida-based Holtec International, which also manufactures the casks.
A dozen of those storage containers already have arrived at Vermont Yankee, and more are on the way: Cohn said the plan is to load 27 casks in 2017.
Lynch said crews have finished installing a new, 200-kilowatt diesel generator that will service the spent fuel storage facility. They’ve also completed demolition of a warehouse that stood where the second fuel pad will be built.
When winter arrives, “we’ll take a break on that project and start again in the spring,” Lynch said.