November 15, 2007

Comanche Peak Steam Electric Station, Glen Rose, Texas

Dr. Robert Peltier, PE

Comanche Peak, Luminant’s (formerly TXU) only nuclear plant, has two 1,150-MW pressurized water reactors (PWRs) that went into service in April 1990 and April 1993, respectively. Bechtel Power Corp., working with Luminant, completed a modernization project on Comanche Peak Unit 1 in April 2007 that shattered the record for fastest replacement of aging components at a nuclear power plant.

 

Bechtel’s long experience with steam generator (SG) replacements prepared it for perhaps its most ambitious project to date. As the prime contractor, Bechtel replaced four SGs and a reactor vessel head in Unit 1 during an outage that lasted just 55 days—eight days less than the previous record for a PWR SG replacement outage alone and 10 days under the original aggressive goal set when the project was awarded to Bechtel in 2004.

It’s a small world

Logistical support for nuclear plants is not a U.S.-centric business these days, and the world’s few nuclear-capable manufacturing facilities have plenty of business. Luminant made its purchase of new steam generators in Spain, transported them by barge to Houston, and then delivered them to the plant by a specially equipped train. Train tracks to the plant were upgraded to handle the loads because they had not been used since the plant was built. The new reactor vessel head, also fabricated in Spain, was outfitted with new control rod drives in Pennsylvania, transported by barge to Houston, and then trucked to the site.

The upgraded design of the new steam generators required installation of rerouted main feedwater piping, along with new seismically designed hangers, snubbers, and whip restraints. Rerouted feedwater piping interfered with existing containment building ventilation ductwork, so that ductwork also required rerouting and new seismically qualified hangers. The new steam generators’ instrument tap locations required that new instrument tubing as well as new hangers be installed. The project work scope for the new reactor head also included providing new cabling, new cable trays, and a new air-handling unit with all new ductwork.

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