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Progress Energy Inc.'s willingness to consider "dry-cask" storage for spent nuclear fuel at two of its nuclear power plants in the Carolinas doesn't extend to its nuclear reactor in Crystal River.
Environmentalists and some industry experts say dry storage is safer than traditional water-filled cooling pools. But Crystal River reconfigured its pools two years ago to store more spent fuel in the same amount of space, which should meet the reactor's storage needs through 2014. By contrast, Progress' plants in Hartsville, S.C., and Southport, N.C., are mulling dry storage because their cooling pools have run out of space and can no longer be reconfigured, according to Progress spokesman Keith Poston.
Increasing the density of cooling pools is a common practice in the nuclear industry, which relies on pools for most long-term storage of spent fuel. Due to a lack of off-site storage facilities for spent fuel, the Nuclear Regulatory Commission has allowed high-density storage in pools that were designed to hold far smaller inventories, according to a report published this year in the Princeton University research journal Science and Global Security.
Because of the intense thermal heat generated by spent fuel newly removed from a nuclear reactor, increased storage density heightens the risk that the fuel could catch fire, which could lead to a catastrophic release of radiation, the report said. Given these risks and the added concerns about terrorist attacks, the report's researchers recommended that all spent nuclear fuel be transferred from cooling pools to dry storage within five years after being removed from a reactor.
Some of the waste in Crystal River's cooling ponds has been there for as long as 25 years.
Dry storage entails placing spent fuel rods in reinforced concrete casks, which can be dispersed and stored above ground, sometimes in bunkers. In addition to reducing the storage density of spent fuel, dry storage involves no moving parts and so is less susceptible to potential problems, according to David Lochbaum, nuclear safety engineer for the Union of Concerned Scientists in Washington. He notes that cooling pools must continuously monitor water levels and circulate the water in the pools to prevent evaporation.
Because dry casks are more dispersed, a terrorist attack would cause less damage than an attack on a cooling pool, says Jim Warren, executive director of the Durham, N.C., environmental group N.C. Warn. "It's a matter of scale," Warren says.
Progress' possible shift to dry storage at some of its nuclear plants has nothing to do with safety concerns but is motivated by simple economics, Progress' Poston said.
Once cooling pools can no longer be reconfigured to increase storage capacity, building dry storage makes sense economically because it's simpler and less expensive to build than additional pools, Poston said.
"Dry storage and wet storage are equally safe," he said. "In fact pool storage is the industry standard."
- Louis Hau can be reached at hau@sptimes.com or 813 226-3404