Nuclear Unit Trips Offline in Arizona

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Researched by Industrial Information Resources (Sugar Land, Texas)--A malfunction of a steam chest valve on the 1,243-megawatt (MW) Palo Verde 1 caused the unit to trip offline early October 22, 2007. The steam chest valve is a control valve that is utilized to reduce thermal stresses in a steam turbine. In addition to this, malfunction engineers have said that they were having some transmission-line issues. As of now, officials are looking at four to five days of maintenance, hoping to have this unit at full power within the estimated time frame.

Palo Verde has been the largest generator of nuclear power since the mid-1980s with three units capable of producing 3,825 MW of electricity. The plant is about 35 miles west of Phoenix in Tonopah, Arizona. Palo Verde is operated by Arizona Public Service Company (APS), and owned by a consortium of seven utilities in the Southwest. APS is the largest stakeholder in the generating facility at 29.1%.

Unit 1 at Palo Verde houses an ALSTOM pressurized water reactor with a rated capacity of more than 17 million pounds per hour of steam at 1,070 pounds per square inch. This steam is used to drive a 1,243-MW GE tandem compound steam turbine generator. The unit commenced commercial operation in 1986.

Plant ID: 1015283
Outage ID: 63001

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