Recycling a legacy of the Cold War
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The tons of surplus plutonium stockpiled in the United States and the former Soviet Union are no longer of interest to anyone...except perhaps terrorists.
This realization led to an agreement between the United States and the Russian Federation to dispose of 35 metric tons of plutonium each by removing the plutonium "pits" from the nuclear weapons and turning them into nuclear power plant fuel.
Rick Brouns is leading a team of Battelle scientists and engineers from Pacific Northwest National Laboratory and Battelle to help Washington Group International design the Pit Disassembly and Conversion Facility in the United States.
"Not only will these two new facilities recycle nuclear weapons into useful fuel and eliminate their costly safeguarding in perpetuity, but they will eliminate nuclear weapons as a potential commodity for terrorists," said Brouns, who manages Battelle's involvement in the project. The project is sponsored by the National Nuclear Security Administration.
The Pit Disassembly and Conversion Facility will convert the plutonium "pits" from nuclear weapons into an oxide form that will be used as a component of a mixed oxide fuel. At least one utility company has already agreed to use the recycled fuel in its nuclear reactors.
The team is responsible for material safeguards and security, environmental protection and worker safety aspects of the facility's design, as well as overseeing the integration of the plutonium processing, which is being developed by another national laboratory.
In addition to setting up the complex material control systems to ensure none of the special nuclear materials are smuggled out of the plant, the scientists and engineers are specifying the design of the physical security systems that prevent unauthorized access. "It's a unique facility in that regard," Brouns said. "We've created numerous barriers to deny access by potential adversaries, such as building it partially below ground with an engineered cover and berm."
The team also is designing a facility that meets all environmental health and safety regulations while maintaining overall security. "One of the unique features of this facility is its use of a safe haven concept for protecting workers during an emergency evacuation," Brouns said. "In the event of a major accident, natural disaster or other threat, the workers will evacuate to below-ground holding areas called safe havens. In the safe haven, they are removed from the potential threat while security personnel maintain control." NNSA is adopting the team's safe haven approach as the standard for other new facilities.
And both the facility workers and the public must be protected from the hazards of handling large quantities of lethal radioactive materials. "We provide the analysis and calculations for minimizing radiation exposure to the workers during regular operations and preventing accidents that could lead to high levels of exposure to both workers and public," Brouns said. "In a facility that handles large amounts of fissionable materials, accident prevention is a huge issue with major design and operating cost implications."
Brouns and his team analyze the systems used in the pit disassembly and conversion process, using various modeling techniques, to determine whether the dose rates to workers is acceptably low and the potential for accidents is extremely unlikely. When the exposures are too high or the accident risks can be further reduced, the team works closely with Washington Group International engineers to redesign the systems. For example, automated material control systems have been implemented in the design to reduce the potential for human error.
"We are overseeing design of the plutonium process technology being developed at another national laboratory because PNNL scientists have worked with plutonium for over 40 years in support of the Hanford Site missions and have successfully implemented first-of-a-kind nuclear processes in other facilities," Brouns said.
The design of the Pit Disassembly and Conversion Facility will be completed in the next year. Construction will start as soon as Congress approves DOE's funding plan. The facility will have a 20-year design life with the goal of processing 35 metric tons of plutonium weapons over a 10-year period.