Nuclear, Reactors

Entergy’s Arkansas Nuclear One Unit 2 reactor vessel head passes inspection

RUSSELLVILLE, Ark., May 6, 2002 — Unit 2 at Entergy’s Arkansas Nuclear One is back on line, generating electricity after shutting down for refueling April 12. Unit 2’s 15th refueling outage ended Saturday after 21 days 18 hours, cutting four days off the world duration record for units designed by Combustion Engineering.

In addition to replacing about a third of 177 fuel assemblies in the Unit 2 reactor, major outage work included inspections of the reactor vessel head and steam generators and extensive turbine maintenance.

The reactor vessel head was determined to be in good shape. All 90 nozzle penetrations were thoroughly inspected and found to be leak-free. Inspections of reactor vessel heads for pressurized water reactors have taken on a new significance since February when severe reactor vessel head corrosion was discovered at the Davis Besse nuclear plant in Ohio. The corrosion there resulted from leakage of reactor coolant containing boric acid, an additive that regulates reactor power by absorbing neutrons. This condition is unique to pressurized water reactors.

Unit 2 comes out of this refueling outage capable of generating about 107 megawatts more electricity. The Nuclear Regulatory Commission recently approved a 7.5 percent increase in thermal power of the reactor. This increase, coupled with efficiency gains from secondary system modifications during this and past refueling outages, yields a total increased gross output of about 11 percent, or 107 megawatts. The added generation means ANO will be capable of supplying electricity for an additional 78,000 homes.

Each of the ANO units is refueled about every 18 months. The previous refueling outage duration record for ANO was 22 days 22 hours, set by Unit 1 last spring during its 16th refueling. That duration was also a record for a Babcock and Wilcox designed unit. Unit 2 was last refueled in fall 2000. That outage featured replacement of the unit’s two steam generators, prominent components for pressurized water reactor systems. Unit 2’s previous shortest refueling outage was 30 days for 2R12 in spring 1997.

The next refueling of Unit 1 is planned for this fall. Between the two ANO units, there have been a total of 31 refueling outages spanning the plant’s 27 years of commercial operation.

Last year was ANO’s best year yet for production. The two units combined to generate 14.7 million megawatt-hours of electricity, the most ever for the site. This equates to about a third of the overall electricity consumption in Arkansas. Unit 2 also set a unit-best record generating 7.9 million megawatt hours of electricity.

The nuclear businesses of Entergy Corporation are headquartered in Jackson, Miss. Entergy, a global energy company based in New Orleans, is the third largest power generator in the nation with more than 30,000 megawatts of generating capacity, about $10 billion in revenue and over 2.6 million customers.

Entergy’s nuclear businesses comprise five reactors at four locations in Arkansas, Mississippi and Louisiana under regulatory jurisdictions and four reactors at three sites in Massachusetts and New York. Entergy Nuclear has also signed an agreement to purchase the Vermont Yankee plant at Vernon, Vt., and expects to close the transaction in the second quarter of 2002. Entergy Nuclear also furnishes license renewal and decommissioning services to the U.S. nuclear power industry.

Entergy Nuclear’s on-line address is