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These lines are expected to be completed in 1973 or 1974. Only one-half of the distance of the lines to Site H and Newport is charged to the Oconee Plant.

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The three units of the Oconee Nuclear Station will be essentially identical. Each will consist of a pressurized water reactor producing steam to drive a turbine-generator. Figure III-4 is a simplified diagram

of one unit. A fairly detailed description of the nuclear steam system

has been published.

One of the reactor units is described below.

The uranium fission chain reaction will occur only in the reactor core, a 12-foot-high close-packed array of fuel assemblies inside the reactor vessel. Each of the 177 assemblies will contain 208 fuel rods, consisting of cylindrical pellets of uranium oxide sealed within zirconium alloy tubes. The rate of the chain reaction will be controlled by neutronabsorbing metal rods that can be moved into or out of the core. Heat produced within the fuel rods will be transferred into water (actually a dilute boric acid solution) that will circulate up through the core. The boron concentration in this primary coolant will be changed as necessary to adjust ("shim") the reactivity of the core. (Boron readily absorbs neutrons.)

When the reactor is operating at full power, heat will be produced at a rate of 2568 megawatts. Primary coolant water will leave the reactor vessel at 604°F and 2200 pounds per square inch; this pressure is high enough to prevent boiling on the fuel rods. The pressure is maintained by electrically heating a sidestream of water to the boiling point in a vessel called the pressurizer. A small amount of hydrogen gas is added to the pressurizer to aid in the recombination of any water decomposed by radiation in the fuel region. The hot primary coolant will pass through tubes in a steam generator, where it will transfer heat to water (secondary coolant) on the outside of the tubes. The pressure will be lower in the secondary system, and the water there will be converted to superheated steam at 570°F and 900 pounds per square inch. This steam will pass through a turbine, driving a shaft connected to a generator which will produce electricity at a rate of 922 megawatts. (About 36 megawatts will be used within the plant, leaving a net electrical output from each unit of 886 megawatts.)

In its passage through the turbine, the steam will expand and cool until it leaves as vapor at 80° to 100°F and at subatmospheric pressure. This vapor will be very pure water, which must be recycled. Recycling will require that the vapor be condensed to liquid water so that it can be pumped efficiently. Condensation will take place on the outside of tubes cooled by lake water being pumped through them. For each reactor unit, heat will be transferred from the condensing vapor to the cooling water at a rate of about 1650 megawatts.

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