Nuclear plants warned to watch for damage
YORK (AP) — Federal authorities are warning nuclear power plants that store spent fuel in dry casks to watch for water damage, citing two incidents at central Pennsylvania plants.
The York Daily Record reported the U.S. Nuclear Regulatory Commission issued an information notice last week detailing how moisture can degrade structures and components associated with spent fuel storage.
“By obtaining baseline measurements and performing periodic evaluations, accelerated degradation can be detected before the structures and components of a storage system are unable to perform their intended function,” the commission said.
The notice cited two separate instances involving water damage to containers holding spent fuel from the Peach Bottom Atomic Power Station in York County and Three Mile Island in Dauphin County.
In 2010, a low-pressure alarm on one of the 115-ton casks holding spent fuel from the Peach Bottom plant indicated that a small amount of helium had leaked. Officials said no radiological material had leaked and the public was not endangered. Later investigation determined that water had caused the outer portion of the lid seal on the cask to corrode.
The commission said the plant and container manufacturer improved the design and came up with a way to verify the integrity of the cask’s protective cover.
Water was also blamed for cracks on concrete storage units protecting spent fuel and debris from the damaged core of Three Mile Island’s Unit 2, which is stored in Idaho. In 1999, Transnuclear installed the concrete enclosures to cover and protect the material but a year later officials started noticing insignificant cracks in the units. In 2007, officials said, seasonal freezing and thawing of water trapped near the roofs and in the cracks of the enclosures worsened the problem.
A later independent engineering study concluded that the units remained effective in protecting the canisters, despite the cracks, the inspection report said. Officials have repaired them and are monitoring any further water damage.