Bechtel Power Corporation has won a contract to provide engineering, procurement and construction services for replacement of two steam generators and the reactor vessel closure head at Davis-Besse nuclear power station in Oak Harbor, Ohio.

Davis-Besse, operated by FirstEnergy Nuclear Operating Company is a 971MW pressurized water reactor.

The replacement steam generators, which are each about 74 feet tall, 12 feet in diameter and weigh 550 tons, will be installed during the scheduled refuelling outage in early 2014. Bechtel will deploy over 500 people to support the replacement project.

Bechtel was the original Architect Engineer for Davis-Besse when the plant was constructed in the 1970s. It also replaced the RPV head in 2002, after a football-sized cavity – caused by corrosion – was discovered in the vessel head.

Although the corrosion did not lead to an accident, it was considered to be a serious nuclear safety incident. The plant remained shut down until 2004 and the Nuclear Regulatory Commission imposed conditions on its restart.

The restart order required Davis-Besse to perform annual independent assessments in the areas of operations, engineering, corrective actions, and safety culture for five years. It also required a one-time inspection of key components on the reactor vessel during a mid-cycle outage to make sure it wasn’t again subject to boric acid corrosion. The order was issued to give the NRC an additional measure of confidence that the company would maintain focus on the areas that had contributed to the reactor vessel head degradation. In September the NRC determined that the operator had met the conditions of the 2004 order.