Addition to Nuclear Plants' Capacity Questioned
By New York Times
CSA Z463 Electrical Maintenance
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In the last two decades, nuclear plants have won permits to uprate, meaning add capacity to reactors, with almost no opposition. With these upgrades, plus expanded working hours and 20-year extensions on operating licenses, the nuclear industry has expanded its electrical output to a point that safety experts say could be dangerous.
For their part, plant owners say they are modernizing in way that can improve safety.
But a battle line has been drawn over an application by Entergy Nuclear to raise a reactor's power output by 20 percent.
Some nuclear engineers outside the company hope they can mount a serious technical challenge to this application so it will not sail through as the previous 99 applications have.
Entergy Nuclear applied in September to the Nuclear Regulatory Commission for permission to raise the power output of a 32-year-old reactor it owns, the Vermont Yankee, by 20 percent.
In considering additions of capacity the commission has changed the way it measures the risk that emergency cooling water, which is needed to dissipate heat at the higher power level, will boil into steam during an accident.
If the water turned into steam, it would make cooling impossible, the fuel could melt, and radioactive material would be released.
The Vermont plant is exempt from some government safety regulations because it was licensed before they were written, and it is now trying to reduce its safety margin "far beyond anything that could be licensed today," said Paul M. Blanch, an engineer with decades of experience in the nuclear field.
While no one has ordered a new nuclear plant in this country since 1973, except for those that were canceled before completion, the 103 reactors now licensed have not only added capacity but will add the equivalent of another two or three plants in the next few years, industry and government experts say.
These uprates, involving mostly minor changes that allow more power production, helped allow the nuclear industry's share of American power production to stay around 20 percent even with no new plants.
Plant managers say that the Vermont Yankee, in Vernon, Vt., just north of the Massachusetts border, was built with enormous unused capacity. And nuclear experts, even some who say that Vermont Yankee's application should receive extra close scrutiny, say that increasing power output can make a plant safer because modernization may include installing more precise, reliable components.
According to Entergy's plans, when Vermont Yankee is next refueled with fresh uranium, technicians will put in more of the type that is easily split to produce energy, and workers will install water pumps that will deliver more water so the reactor can produce more steam. The company will also install a new turbine, which takes the energy of the steam and uses it to turn a shaft, and a new generator, which uses the shaft's energy to make electricity.
The reactor's current capacity of 524 megawatts of electricity would rise to 634; one megawatt would keep 1,000 window air-conditioners running. Experts say this upgrade will probably cost about $60 million — far less expensive than creating the equivalent by building a new plant. Fuel expenses would rise somewhat, but not the long-term labor and maintenance costs.
That economic logic has appealed to the nuclear industry, especially as the electric industry restructured over the last few years and some reactors were sold.
"As people began to look at competitive markets and renewing the operating licenses, they said, `If I make a little more investment in this plant, I can uprate it even further,' " said Marvin Fertel, the chief nuclear officer at the Nuclear Energy Institute, an industry trade group.
