Work to install a new reactor vessel head at the Davis-Besse Nuclear Power Station in Oak Harbor, Ohio, started early on 1 October. FirstEnergy Nuclear Operating Company (FENOC), which operates the 900MW reactor had originally scheduled the vessel head replacement in 2014. However, it decided to accelerate the works after modifications hwere needed to 24 of the 69 control rod nozzles on the current head in a spring 2010 refueling outage.
"Advancing the installation of the new reactor head provides additional margins of safety and reliability for long-term plant operations," said James Lash, president of FirstEnergy Generation and chief nuclear office.
The new head will replace the one installed in 2002. It is almost 17 feet in diameter, eight-feet tall and weighs more than 82 tons. Areva manufactured the reactor head in France and it was inspected by FENOC before being shipped to Davis-Besse in November 2010.
Once at the plant, the new reactor head was placed in a specially constructed building where new control rod drive mechanisms and other components were fitted and installed. The new head will be moved in and the old head removed from the plant via an opening that will be cut into the containment building during the outage.
Other work scheduled during Davis-Besse's maintenance outage includes installation of a new reactor control system and upgrading several battery chargers that provide DC power to important plant components. In addition, the station will replace underground piping in a water system that provides cooling to plant equipment and systems.
Around 1000 workers will be involved in the outage work.
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