The casks now holding the irradiated parts of Humboldt's old nuke are made up of three shells. An inner shell for containment, a series of thick steel intermediate shells for gamma shielding and an outer enclosure shell that houses the neutron shielding material, according to Holtec. The casks, in turn, are tucked inside a vault made of reinforced concrete between 3-feet and 7-feet thick. According to Holtec, the manufacturer, "Humboldt Bay became the first plant to feature subterranean storage, which is so unobtrusive and produces such a negligible [radiation] dose that the path to the beach runs in close proximity to the [storage site]!"
The casks are meant to "temporarily" hold the waste for 100 years or so. If the scientists who predict a 240,000-year toxicity are correct, that would leave 239,900 years, and for that, there's no plan. Yet, some local environmentalists are laying the groundwork to plan for site protection at least into the next century. They foresee a drowning bluff and an unsuspecting future generation.
"If the bay is our region's most important resource, the future integrity of the [storage] site, which sits 115 feet from the shoreline, across the mouth of the entrance to the bay, is a big deal," noted Jennifer Marlow, an assistant professor in Humboldt State University's Department of Environmental Science and Management. "For example, with 2 meters of sea level rise in Humboldt Bay, monthly and annual high tides could overtop the protective revetment wall protecting the bluff."
"According to the Ocean Protection Council's 2018 sea level rise projections, 2 meters of sea level rise could occur 'as early as 2076 under the extreme scenario, or by 2093 under the high-risk projection.' If either scenario comes true, it is likely that the spent nuclear waste will still be onsite. The California Coastal Commission has stated that, given the lack of an alternative permanent storage site, it 'must presume' that the spent nuclear waste will remain on site 'in perpetuity.'"
That phrase, "in perpetuity," underscores a heavy responsibility.
"It's unlikely that there will ever be a permanent national repository," said Humboldt Baykeeper Director Jennifer Kalt. "Waiting for that is not realistic. Ultimately, there's no safe place for the waste. Moving it will be dangerous and controversial and expensive, but it needs to be moved farther from the bay, out of the sea level rise hazard area. We need to start figuring out a real plan. Otherwise, we're just leaving the problem for future generations to deal with."