The Hanford Site is a U.S. Department of Energy (USDOE) owned/contractor operated facility located near Richland, Washington, in the Southeastern portion of Washington State. The 586-square mile site supports programs in waste management, environmental restoration, science, technology and energy. Hanford was established in secrecy during World War II to produce plutonium for America’s defense program. Peak production years were reached in the 1960s when nine production reactors were in operation at the Site. During this period, Hanford operations generated large volumes of high-level radioactive and hazardous chemical wastes. Hanford’s reactor sites were like self-sufficient cities.
Cocooning for Interim Storage
Today many of the reactor support facilities have been demolished and the reactor blocks are being "cocooned" for interim storage. The cocooning process involves removing all of the reactor building except for the five-foot-thick shield walls surrounding the reactor core. Openings and penetrations are sealed with corrosion resistant materials and a 75-year roof is placed over the remaining structure. The facility is equipped with heat and moisture sensors that are remotely monitored. 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 while significantly reducing surveillance and maintenance costs. Reactors can remain in the cocooned state for up to 75 years. This will provide time for the USDOE, regulators and stakeholders to determine the final disposal method and to allow radiation levels in the reactor cores to decay to more manageable levels.
The first of Hanford’s nine plutonium production reactors to be cocooned was C Reactor. The cocooning was carried out like a reverse construction project. This involved reducing the size of the 60,000-square-foot reactor building by more than 80%. Much of the demolition work in the interior of the reactor building focused on removing equipment such as the 29 vertical safety-rod lifting assemblies. Once the assemblies were removed and housings penetrating the reactor core were sealed, three stainless steel hoppers containing high-efficiency particulate air filters were installed to trap any potential contaminants vented from the reactor core as it naturally "breathes." After decontamination, workers also removed more than 181.2 cubic meters (6,400 cubic feet) of asbestos, 285,762 kilograms (630,000 pounds) of materials contaminated by low-level radiation, 104.3 metric tons (115 tons) of steel and copper and 189,250 liters (50,000 gallons) of contaminated water.
Removing the reactor’s fuel transfer pits posed a major technical challenge. Some of the pits held sediment from the fuel storage basin floor and contained significant quantities of plutonium. Through sampling, it was clear that any movement of the sediment caused the plutonium to become airborne, creating serious risks to worker safety. The removal option chosen was based on the lowest radiological exposure to employees and cost. Employees poured a concrete cap over the sediment in the transfer pit. All surrounding structures were demolished, and the monolith that was created was then cut to a 12-foot cube. It was removed in two 70-ton lifts and transported for onsite disposal.
D&D Technology Demonstration
While major portions of the C Reactor Complex were disappearing, C Reactor also served as a demonstration of innovative Decontamination and Decommissioning (D&D) technologies. At least 20 technologies and approaches were field tested to demonstrate safer, less expensive and more efficient ways of decommissioning aging facilities. In 1997, 11 of these innovative technologies were demonstrated, of which eight were adopted—replacing baseline technologies. Four of these technologies were also deployed for other Hanford Site and USDOE Complex projects and one technology was selected for use at the Chornobyl reactor in Ukraine.
In 1998, Bechtel Hanford, Inc., USDOE’s prime Environmental Restoration Contractor (ERC) at Hanford, completed the cocooning of C Reactor in just over two years for $27.8 million. The reactor "footprint" was reduced by 81%. One remaining door was welded shut, to be opened only once every five years for an internal physical inspection. In the meantime, sensors and a television camera monitor the interior.
Recently, workers entered C Reactor to make the first five-year inspection and found it about the same as they had left it. The team used a new high-resolution digital camera with newly developed software that enables the creation of 360-degree photographs. These photographs will be used to develop a virtual tour of the interior for future comparison. System users can zoom in to specific areas of interest and see them from all angles and in greater detail without having to enter the facility. This recent surveillance of C Reactor confirmed that cocooning creates a safe, environmentally secure structure while significantly reducing the surveillance and maintenance costs. Based on the results, the ERC team is evaluating whether the five-year period can be extended safely, reducing surveillance costs even further.
Five Reactors Complete or In Progress
As the ERC team completed work on C Reactor in 1998, they developed efficiencies that allowed them to complete DR Reactor in cutting the cost of cocooning nearly in half. Work is continuing on F, D and H Reactors. The F Reactor demolition is complete and a new roof has been installed, with cocooning to be completed in September 2003. D Reactor demolition is complete and the final step will be to install a new roof. Demolition of H Reactor is progressing with cleanout of the fuel storage basin to continue through most of 2003. Cocooning work will continue through 2004 on both D and H Reactors. Cocooning of D Reactor is scheduled for completion in 2004; H Reactor is scheduled for completion in 2005.
According to the Tri-Party Agreement between USDOE, the Environmental Protection Agency and the State of Washington, the surplus reactors were not originally scheduled to be cocooned for several more years. As part of USDOE’s effort to reduce risk and accelerate cleanup, the milestones were renegotiated in 2002. All work on DR was completed well ahead of the September 2003 milestone and cocooning of the other reactors will also be accelerated.
Hanford Communities Position
The Hanford Communities have strongly supported the Reactor Cocooning program since its inception and have worked with members of Congress to assure adequate funding to maintain the highly trained team of engineers and craft workers. The Hanford Communities along with others in the community support preservation of the B Reactor as a museum. Efforts are now underway to transfer ownership of the facility to the U. S. Parks Service.
To find out how you can become more involved in this important regional issue, or to have a Hanford Communities speaker talk to your organization, contact the Hanford Communities at (509) 942-7348 or by fax at (509) 942-7379.