Four years after the state adopted a policy to phase out the use of seawater to cool coastal power plants, debate continues over if or whether to retrofit the largest once-through cooled power plant in the state. The discussion, the focus of recent documents, precedes a State Water Resources Control Board meeting on the issue set for Nov. 18. The feasibility and cost of various options for reducing harm to marine wildlife from the massive Diablo Canyon Nuclear Plant in San Luis Obispo is key. The facility is permitted to draw in and expel up to 2.5 billion gallons of coastal water/day. Pacific Gas & Electric, Diablo’s owner, hired Bechtel Corp. to evaluate the feasibility of a range of cooling options—from wire mesh screens to dry cooling towers—to mitigate the killing of fish, larvae, and other sea critters to meet state power plant cooling policy. The policy aims to reduce the “harmful effects associated with cooling water intake structures on marine and estuarine life” including Diablo, San Onofre Nuclear Generating Station, and 19 fossil-fueled plants, according to the Water Board. Diablo’s continuous withdrawals of seawater each year result in 1.5 billion larvae being entrained and 710 pounds of fish being impinged, according to the Water Board. PG&E wants to be exempted from the once-through cooling phase-out because of the high upfront costs of alternatives and ongoing annual costs. PG&E also questioned the effectiveness of various cooling technology alternatives evaluated by Bechtel. “All of the options, but especially the cooling tower options, will require detailed and time-consuming permit application documentation, many governmental approvals, and are likely to face substantial challenges from various organizations,” the utility stated in mid-September. Bechtel’s cost estimates for the alternatives, to be paid for by PG&E ratepayers, include: • $8.6 to $14 billion for freshwater wet- or dry-cooled towers; • $6.2 to $8 billion for saltwater towers; and • $456 to $675 million for the screening technology options—fine and wire mesh. The Water Board’s stakeholder Nuclear Fueled Power Plants Subcommittee rejects exempting Diablo from the once-through cooling policy. It backs closed-cycle cooling as the most effective method for reducing the plant’s aquatic impacts and meeting state policy, but notes “significant logistical challenges” will need to be overcome. In a Sept. 12 response to Bechtel’s August evaluation of plant retrofits, it added, “While there is a wide range of estimated costs associated with the closed-cycle cooling technology, the subcommittee believes that the only definitive way to determine the costs of retrofitting Diablo Canyon is for the utility to competitively bid the project with appropriate risk management and performance terms.” Friends of the Earth, in November 2013, rejected Bechtel’s cost estimate for cooling towers. It asserted that a saltwater cooling tower would be less costly and was feasible because there was adequate space for cooling towers—contrary to Bechtel’s finding. The water cooling retrofit question also is tied up with issue of whether PG&E pursues relicensing the Diablo facility for 20 years beyond its current license expiration dates in 2025. “Ultimately, the decision about retrofitting Diablo Canyon with closed-cycle cooling will be part of the relicensing decision made by the [California Public Utilities Commission] and the [Nuclear Regulatory Commission],” according to the state regulatory and stakeholder subcommittee. The panel, which released comments Sept. 12, includes the CPUC, California Energy Commission, the Center for Energy Efficiency & Renewable Technologies, and Alliance for Nuclear Responsibility.