Nuclear panel questions cask life span
By Christine LegerePosted Nov 29, 2018
Potential Pilgrim buyer outlines plan for spent fuel.
PLYMOUTH — Massive concrete and steel casks, described by their manufacturer as providing “an impregnable barrier,” will protect the public from radiation emitted by the 4,000 spent fuel assemblies left behind at Pilgrim Nuclear Power Station when the reactor permanently shuts down in May.
But how long will that protection last?
Developed by Holtec International, the company planning to buy Pilgrim and handle its decommissioning, the HI-STORM 100 casks are certified by the Nuclear Regulatory Commission for 20 years. Yet the spent fuel contained inside will remain radioactive for thousands of years.
Those facts were troubling to members of the Nuclear Decommissioning Citizens Advisory Panel on Wednesday, as Holtec representatives highlighted the “robust” program they plan for long-term handling of Pilgrim’s spent nuclear fuel.
The fuel assemblies will be placed into stainless steel canisters equipped with baskets of neutron-absorbing material developed by Holtec and capable of withstanding the heat generated by high burnup fuel.
The steel canister is then housed in an outer shell of carbon steel, with 27 inches of poured concrete separating the two.
The casks, each weighing 350,000 pounds, could take a direct hit from an F-16 fighter plane filled with fuel, a Boeing 767 traveling at 350 mph and withstand a raging brush fire with no release of radiation, Holtec representative Joy Russell said.
The company envisions the design life of the casks to be about 100 years, according to Stefan Anton, Holtec’s vice president of engineering and licensing. Once the 20-year federal certification is up, Holtec will return to the NRC for extensions, Anton said.
Advisory panel member John Flores, a Barnstable town councilor, questioned how the 100-year figure was arrived at, since the first such cask was loaded with spent fuel only in 2000.
“The 100-year life expectancy is theoretical,” Flores said. “In reality, 18 years is all you have as evidence.”
Even 100 years falls considerably short of what is needed, noted panel member Daniel Wolf, a former Cape and Islands state senator, who said the fuel would be radioactive for much longer. “We’re putting something that lasts for thousands of years into a container that lasts for 100,” he said.
Panel member Kevin O’Reilly, of Plymouth, asked Anton how his company came to the conclusion a cask could last for 100 years.
“As long as we take care of it, it is going to last a long time,” Anton said.
Inner canisters would be randomly tested for leakage, he said. If a leak was detected, the canister would be placed into a slightly larger one. “We’ve never had to do that,” he said.
Duxbury resident Mary Lampert, president of Pilgrim Watch, pointed out only one canister is chosen for testing. “That doesn’t mean you’ll get the important one — the one with the crack,” she said.
Wolf asked Russell how long the casks were under warranty, and was told the information was confidential since it was a contractual issue.
The answer frustrated panel Chairman Sean Mullin.
“We are the people that are going to have to live with it, so if it’s a confidential contract, that’s going to be a real problem,” he said. “A lot of the answers you have given are soft, so we may come back and ask you in writing.”
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https://www.capecodtimes.com/news/20181129/nuclear-panel-questions-cask-life-span
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