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    Power plants seek to extend life of nuclear reactors

    Reactor operators staffed a control room at Peach Bottom Nuclear Generating Station in Delta, Pa. Proponents say that extending plants’ lifetimes is more economical, and a better way to hold down carbon dioxide emissions, than building more plants.
    Steve Ruark/The New York Times
    Reactor operators staffed a control room at Peach Bottom Nuclear Generating Station in Delta, Pa. Proponents say that extending plants’ lifetimes is more economical, and a better way to hold down carbon dioxide emissions, than building more plants.

    NEW YORK — The prospects for building more nuclear reactors may be sharply limited, but the owners of seven old ones, in Pennsylvania, Virginia, and South Carolina, are preparing to ask for permission to run them until they are 80 years old.

    Nuclear proponents say that extending plants’ lifetimes is more economical — and a better way to hold down carbon dioxide emissions — than building plants, although it will require extensive monitoring of steel, concrete, cable insulation, and other components. But the idea is striking even to some members of the nuclear establishment.

    At a meeting of the Nuclear Regulatory Commission in May, George Apostolakis, a risk expert who was then one of the five commissioners, pointed out that if operation were allowed until age 80, some reactors would be using designs substantially older than that.

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    “I don’t know how we would explain to the public that these designs, 90-year-old designs, 100-year-old designs, are still safe to operate,” he said. “Don’t we need more convincing arguments than just ‘We’re managing aging effects’?

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    “I mean, will you buy a car that was designed in ’64?” he asked.

    But the consensus of the commission staff and the industry is that with appropriate analysis and monitoring, the reactors can generate huge amounts of carbon-free electricity for additional decades. The commission itself has not yet approved a system.

    “If you’ve effectively paid off the plant, this is very cheap power,” said Neil Wilmshurst, a nuclear engineer at the Electric Power Research Institute, a nonprofit utility consortium that has been researching how to keep old plants running. “The whole basis of license renewal is that the plants are being well-maintained — that at the component level, things are being replaced when needed and maintained when needed.”

    The leading candidates are Exelon’s two operating reactors at the Peach Bottom plant in Pennsylvania, 50 miles southeast of Harrisburg; Dominion’s twin Surry reactors, near Jamestown, Va.; and Duke’s three Oconee reactors, near Seneca, S.C., all dating from the early 1970s.

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    “The preliminary analysis we’ve done is favorable,” said David A. Heacock, the chief nuclear officer of Dominion. But obtaining the extension would cost several million dollars, he said, and while Dominion is investigating just what would be needed, it has not decided yet to apply.

    Yet “it’s relatively inexpensive to relicense, compared to any new technology,” Heacock said. If the Environmental Protection Agency succeeds in setting a carbon dioxide emissions cap, he said, extending Surry’s life could save local consumers a lot of money.

    Surry’s steel and concrete are in good shape, he said, and the company is already replacing much of the high-voltage cabling anyway.

    The 100 operating power reactors, most of them completed by the late 1980s, were licensed for 40 years. In that era, new generating stations were expected to replace old ones within a few decades, but that turned out to be wrong for nuclear plants and coal-fired power stations as well. The nuclear industry now describes that 40-year period as an early estimate of the plants’ economic life, not physical viability.

    As construction of reactors tailed off to nearly nothing in the late 1980s, the Nuclear Regulatory Commission established a procedure in 1991 for 20-year license extensions, and it has now granted more than 70. Thus far it has not rejected any applications, although many are still under review.

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    The 1991 procedure allows for plants to receive additional 20-year extensions, but the commission is currently engaged in a major effort to determine the criteria it should set for years 61 to 80. It expects utilities to start seeking a second round of 20-year extensions by about 2018.

    The effort on reactors is part of a trend; airlines, highway departments, water system managers and others are all using major assets for longer than the builders imagined.

    Exposed to decades of radiation, some metal parts grow brittle and more likely to crack under stress. One potential source of stress is the emergency core cooling system; if the system sensed a leak in the piping, it could start up and dump huge volumes of cold water into a reactor, keeping it at operating pressure but at a far lower temperature. Engineers say that could lead to a condition called “pressurized thermal shock,” in which a reactor vessel would crack open.

    To measure embrittlement, the plants use extra samples of the metal from which their reactor vessels were made, called coupons, stored for years in irradiated areas inside the reactors. These have been removed at various intervals and analyzed for brittleness, in a test that usually destroys the coupon.

    A few of the reactors have run out of these coupons, and engineers are trying to draw conclusions about their conditions by extrapolating from coupons in other reactors. In others, they have moved the coupons closer to the center of the reactor, to age them faster, so they have an idea of what the vessel’s metal will look like in a few years, not just its current condition.

    Jim Riccio, a nuclear policy analyst at Greenpeace, said, “This isn’t about running reactors until they are 80. It’s amortizing the large capital additions that the industry can’t afford right now.” The reactors, he noted, have been required to buy new hardware after the Fukushima Daiichi accident in 2011.