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Cocooned F Reactor Gets Five-Year Checkup

08.18.2008

RICHLAND, WA — Workers broke open welds on the steel doors of the cocooned F Reactor last week, welded shut since late 2003, to allow access for the reactor’s five-year inspection team.

The U.S. Department of Energy (DOE), Washington Closure Hanford (WCH), and the Environmental Protection Agency (EPA) performed the inspection as part of a safety and accountability measure.

During the checkup, the team assessed no degradation in the facility over the last five years and no evidence of animal intrusion. The reactor’s current condition is almost identical to when it was sealed in late 2003.

The F Reactor was the third Hanford plutonium production reactor to be placed in interim safe storage – called cocooning. It operated from February 1945 to June 1965.

Cocooning involves demolishing the reactor building down to its three-foot-thick concrete shield walls which surround the reactor core. All openings in the remaining structure are sealed and a new roof is installed. The objective of cocooning is to establish a safe, environmentally secure and stable structure that will protect the public and the environment from potential contamination. A major benefit to cocooning is that it significantly reduces surveillance and maintenance costs. The reactors are expected to remain in this state for up to 75 years.

Cocooning of Hanford’s reactors allows time for DOE and its regulators to determine a final disposal method. It also allows radiation levels to decay to more manageable levels.

Temperature and moisture sensors are used to remotely monitor conditions inside the sealed reactor building. Once every five years, workers will enter the structure to conduct inspections and make any necessary repairs.

To date, five of Hanford’s nine reactors have been cocooned. C Reactor was cocooned in 1998, DR in 2002, F in 2003, D in 2004 and H in 2005. N Reactor and the associated steam generator building are being readied for cocooning to be completed in 2011.