Nuclear storage casks vulnerable to flooding, Pilgrim Station critics argue

Most of the spent fuel at Pilgrim Nuclear Power Station is stored in a pool of water inside the reactor building.

Over the past few years, Entergy has started moving that fuel into dry storage at another location on their property and they say they want to move all of it out of the spent fuel pool and into dry casks once the plant shuts down for good at the end of June 2019. However, critics of the plant are concerned that even outside the pool, the spent fuel may still get wet.

Joe Lynch, a spokesman for Entergy outlined the company’s plans for the spent fuel at Pilgrim Station during a presentation to the Nuclear Decommissioning Advisory Panel, last Wednesday.

According to Lynch, the company has already moved 544 fuel rod assemblies into eight casks located in the north section of the PNPS site. They are on a pad that can hold 40 casks, though the company plans to only put 38 casks on it in order to facilitate their movement, Lynch said.

With 2,990 spent fuel assemblies in the pool and another 580 expected to be added in 2019, the company needs to build an additional pad to accommodate another 38 casks, Lynch  said. The new pad will hold all the spent fuel rods and also contain other radioactive waste produced when the plant shuts down, he said.

Lynch assured the NDCAP that the location of the second pad would have to meet a number of Nuclear Regulatory Commission requirements to handle flooding, earthquakes, tornadoes, fires and explosions. Given that PNPS is located close to the water, the flooding part of that list most concerned many panel and audience members.

Panel member Pine Dubois disputed the figures Entergy is using to determine where the pads could go. According to Lynch, the current pad is 25 feet above mean sea level and is 300 feet from shore. The company did flood evaluations in 2010 and 2015. Dubois said the figures were unreliable because the mean sea level is changing, The mean sea level figure Entergy is using was set in 2003, she said. “That stuff is old,” she said.

Heather Lightner, another panel member, noted the location of the current pad was chosen because it was close to the reactor building. She asked if that would be a factor in deciding the location of the new pad. Lynch declined to speculate.

The casks, which are 18 feet tall and weigh 173 tons, can be submerged, Lynch said. They are licensed by the NRC for 20 years, though they are, he said, designed to last longer. However, Mary Lampert of Pilgrim Watch stated that NRC regulations allow them to start showing cracks after 30 years. According to her, similar casks at the Diablo Canyon reactor in California are already showing wear. The casks, she said, where only designed for comparatively short-term storage until the nuclear waste  is moved to a permanent location.

Besides the dangers of flooding, Jim Lampert of Duxbury raised questions about the casks vulnerability to terrorist account. The NRC standards don’t account for that, he said. NRC rules require the casks be located in an secure area controlled by the owner, Lynch said.

The process for deciding on what vendor to use for the casks and where to locate them could take over a year, Lynch said. Besides NRC regulations, the siting would also be subjected to local approval, he noted.

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