VERNON — Entergy Nuclear has begun the transfer of close to 3,000 nuclear fuel assemblies from the Vermont Yankee spent fuel pool into dozens of concrete and steel casks. The painstaking transfer, which will take until the end of 2018, is a milestone in the decommissioning of the Vermont Yankee plant, which shut down in December 2014 after more than 40 years of operation. A total of 2,996 fuel assemblies will be moved. Since 2008, Vermont Yankee owner Entergy Nuclear has removed 884 fuel assemblies from the pool and put them in what the nuclear industry calls “dry cask storage.” At that time, the transfer was viewed as giving Vermont Yankee additional storage space for its spent fuel, so it could continue operating. The transfer, which started Monday, means Entergy is two years ahead of its original schedule for transferring the fuel out of the plant’s reactor building into passive, aircooled storage containers, according to Joe Lynch, an Entergy spokesman. The company has transferred spent fuel in 2008, 2011 and 2012, and currently there are 13 casks full of old fuel. At the end of the transfer, 58 casks will be filled and on site. Entergy must complete the transfer of the radioactive fuel, which remains dangerous for thousands of years, as a condition of the sale of Vermont Yankee to NorthStar Group Services Inc., a New York City industrial demolition company. NorthStar is seeking approval for a license transfer from the Nuclear Regulatory Commission, as well as state approval from the Public Service Board. Lynch said Holtec International, the manufacturer of the dry casks Entergy is using for the long- term storage facility, is performing the fuel movement, under Entergy’s supervision. The 45 new casks will be moved to a concrete pad at the Vernon site, which is known as the independent spent fuel storage installation. Entergy received approval from the PSB earlier this year to build the second storage pad facility. The transfer of the spent nuclear fuel has long been supported by nuclear critics. “It’s a good thing that the fuel is going from the pool into dry cask storage,” said Arnie Gundersen o f Burlington, a nuclear engineer who has been a critic of Vermont Yankee’s owners. “ The reason it’s good, the pool is active, there are pumps that cool it. If the pumps fail you can have catastrophic results. The new pad, it’s totally passive.” He added, “It’s a good thing that the fuel i s being transferred. But there are two significant problems. School is still in session. I would wait until school is out. Why can’t they wait until school is out?” Vernon Elementary School is less than 4,000 feet from the nuclear reactor, Gundersen said. By waiting, he said, Entergy has “ one less problem to worry about.” The last day of school is Friday. “If it’s this close, why they can’t wait until school is out?” Gundersen noted Entergy had problems with the brakes on the giant lift that moves the uranium fuel into the casks during the first move in 2008. The crane must move 110 tons — the equivalent of 100 cars, he said. The concrete and steel cask weighs 70 tons each, and Entergy must load 40 tons of uranium fuel into the casks. “ All the more reason not to have the kids there,” he said, noting he had made the suggestion to Entergy officials in 2014.