Water & Energy: Diablo Water Use Lined to Re-Licensing

By Published On: November 20, 2014

Plans to extend the operating license for the Diablo Canyon nuclear plant may run afoul of state regulations requiring a phase-out of once-through ocean water cooling for power plants. The state is being urged to require a retrofit to conserve water that could cost Diablo’s owner, Pacific Gas & Electric more than $14 billion. Given that, PG&E implored the State Water Resources Control Board to give the utility a variance from state water cooling phase-out rules. To meet California’s requirement to phase out once-through water cooling for power plants, state agencies and other stakeholders want the Diablo Canyon nuclear plant to switch to closed-cycle cooling if PG&E chooses to license the plant for another 20 years. The current federal licenses expire about 2025. “Closed-cycle cooling is a viable technology,” Melissa Jones, California Energy Commission senior policy analyst, told the board Nov. 18. The Energy Commission, the California Public Utilities Commission, and the Alliance for Nuclear Responsibility are part of the subcommittee on nuclear power plant water cooling. A retrofit to change from seawater cooling to closed-cycle is “enormously complex,” responded Kent Kauss, PG&E director of state government relations. It’s also expensive. Estimates to build a new cooling system range from $8.5 billion to $14 billion. All parties to the discussion have basically ruled out options other than building new cooling towers. Those options are wedge wire screening and fine mesh screens. The utility and stakeholders agreed those options are, as Kauss said, “not efficacious.” That leaves closed-loop saltwater cooling and freshwater cooling. Saltwater, said Kauss, would leave 900 tons/year of salt for the utility to dispose. Freshwater cooling construction “would take a mountain-sized excavation and incredibly high costs.” Bechtel, the company hired to provide engineering options and cost estimates, showed closed-loop cooling tower sketches that would loom over the already-massive nuclear plant. Bechtel project manager Dan Williams did not take his company out of the running to build a closed-loop system if that’s what is eventually required. The state board is considering the options. At a permitted intake of ocean water of up to 2.5 billion gallons/day, Diablo Canyon now is responsible for 78 percent of ocean water usage at the state’s once-through water-cooled power plants, according to Jones. The intake kills fish, fish larvae, and other sea creatures. When expelled at a higher temperature than surrounding water, the cooling water basically “bleaches” out the marine environment surrounding the release pipes, according to the Central Coast Regional Water Quality Control Board. “There is no basis” for the exemption PG&E seeks from the state phase-out of once-through water cooling, noted the Subcommittee of the Review Committee for Nuclear Fueled Power Plants. Although not discussed Nov. 18, the subcommittee proposed the water issue be “part of a larger discussion regarding re-licensing of the facility.” The subcommittee noted that “ultimately, the decision about retrofitting Diablo Canyon with closed-cycle cooling will be part of the re-licensing decision made by the California Public Utilities Commission and the Nuclear Regulatory Commission.

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