July 11, 2012
Covert, Mich. - Control room operators at Entergy's Palisades nuclear plant returned the plant to service on Wednesday, July 11 at 2:36 a.m. EDT, ending a 28 day, 7 hour, 47 minute outage to conduct repairs to the plant's Safety Injection / Refueling Water tank. The plant will be increased to full power operation over the next several days. The aluminum SIRW tank is 50 feet in diameter and 35 feet tall. It holds up to 300,000 gallons of borated water that is used to fill the reactor cavity during refueling outages and to act as a source for the plant's safety injection system in the event of a loss of coolant accident.
Palisades was removed from service on June 12 when leakage from the tank exceeded an administrative limit of 31 gallons per day. The water leakage had been monitored, collected, and analyzed by Operations and Chemistry personnel since April 28. Hundreds of feet of floor plate, floor-to-wall plate, seam, and circumferential welds were examined during the outage using five different weld examination techniques. Potential weld flaws were identified, and those with minor through-wall leak paths were repaired. In addition, several modifications were performed on tank internal components to enhance structural integrity. Palisades, Entergy fleet, and tank construction and inspection experts from across the Midwest were on site to provide technical guidance during the repair process.
During the July 6 tank refill, water was observed coming from a sand bed that provides support for the tank's floor and reduces flexing of the metal. This was expected since previous tank leakage had dampened the sand under the tank. The residual water was now being forced out of the sand by the combined tank weight and the water being placed inside. The leaking water was captured in collection trays for analysis. Upwards of 20 gallons per day was collected initially and this amount has steadily decreased to 0.67 gallons per day collected on July 10.
With nuclear safety as the primary focus and consideration, based on the information learned about the sound structural integrity of the tank, the multiple non-destructive examination methods used, and input from industry-wide, fleet and Palisades' expertise, the decision was made to proceed with plant restart. Compensatory measures are in place to capture any tank leakage now and in the future, and actions are ready to be taken if tank leakage exceeds established administrative limits.
Entergy Corporation is an integrated energy company engaged primarily in electric power production and retail distribution operations. Entergy owns and operates power plants with approximately 30,000 megawatts of electric generating capacity, including more than 10,000 megawatts of nuclear power, making it one of the nation's leading nuclear generators. Entergy delivers electricity to 2.8 million utility customers in Arkansas, Louisiana, Mississippi and Texas. Entergy has annual revenues of more than $11 billion and approximately 15,000 employees.