Description: South Carolina is the third largest generator of nuclear electricity. The pair of light water reactors at the Catawba plant are the largest reactors in the State although, with three reactors compared to Catawba’s two, the Oconee plant has the most nuclear capacity in South Carolina.¹ Catawba is located on a 391-acre peninsula.

Catawba, Unit 1²

Nuclear Steam System Supplier (NSSS Vendor) = Westinghouse
Architect Engineer = Duke
Owner = North Carolina Electric Membership Corporation (56.3 percent), Duke Energy Corporation (25 percent), Saluda River Electric Coop, Inc. (18.8 percent).
Operator (Licensee) = Duke Energy Power Company, LLC

Catawba, Unit 2

Nuclear Steam System Supplier (NSSS Vendor) = Westinghouse
Architect Engineer = Duke
Owner = Duke
Operator (Licensee) = Duke Energy Power Company, LLC

Pressurized-Water Reactor (PWR)

In a typical commercial pressurized light-water reactor (1) the reactor core generates heat, (2) pressurized-water in the primary coolant loop carries the heat to the steam generator, (3) inside the steam generator heat from the primary coolant loop vaporizes the water in a secondary loop producing steam, (4) the steam line directs the steam to the main turbine causing it to turn the turbine generator, which produces electricity. The unused steam is exhausted to the condenser where it is condensed into water. The resulting water is pumped out of the condenser with a series of pumps, reheated, and pumped back to the steam generator. The reactors core contains fuel assemblies which are cooled by water, which is force-circulated by electrically powered pumps. Emergency cooling water is supplied by other pumps, which can be powered by onsite diesel generators. Other safety systems, such as the containment cooling system, also need power.

© U.S. Nuclear Regulatory Commission

Containment: Both reactors are PWRs with wet, ice condenser containment.³

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¹With the return to service of Browns Ferry 1, the Browns Ferry Plant in Alabama is now the only plant in the southeast with more capacity than Oconee.

²The South Carolina Office of Regulatory Staff notified this Agency that percentage of ownership for unit 1 may change soon. For more information, consult their website at http://dms.psc.sc.gov/dockets/dockets.cfc?Method=DocketDetail&DocketID=103421

³ Wet, Ice Condenser containment: A reactor containment design whose safety has been evaluated on the basis of a dry air atmosphere at ambient pressure AND an ice condenser present prior to the onset of a loss of coolant accident or steam pipe break. The containment design (concrete and steel tendons and ice melting) must be able to take the full thermal and pressure stress associated with the rapid energy release (steam) from a major pipe break. In lay terms, these containments have huge refrigerator ice trays in them that are stocked with abundant ice. If there is an accident, the pipe break leads to a rapid build up of steam and air pressure in the inside of the containment. NOTE: as air is heated in an enclosed space, it expands and hence pressure builds up. Also, as liquid water from the reactor flashes to steam, it occupies a much larger volume than the liquid did. This also builds up pressure inside the containment and could burst the walls. So, with ice condenser containment, the steam hits the stored ice. The ice melts and in doing so, robs the steam of some of its thermal energy. The air which is mixed with the steam stays cooler and does not expand so much. The ice also condenses the steam back into water thereby reducing the steam volume and pressure in the containment.

Sources for Data in Table: Capacity, for purposes of this report, is the net summer capability as reported in Energy Information Administration (EIA) Form EIA-860, "Annual Electric Generator Report." Capacity Factor is a percentage calculation in which the maximum possible generation (based on net summer capability) is divided into the actual generation then multiplied by 100. Generation is the net electricity output reported by plant owners on Form EIA-906, “Power Plant Report.” Type of Unit: All U.S. commercial reactors currently in operation are one of two types: BWR (boiling water reactor) or PWR (pressurized light water reactor). The type, on-line date, and the license expiration date are published annually in Information Digest by the U.S. Nuclear Regulatory Commission.