Collaborative effort moves Lab step closer to shipping surplus plutonium off site
By Lynda Seaver
Newsline staff writer
The Lab has moved significantly closer to shipping its surplus plutonium off site, thanks to a collaborative effort between researchers from the Lab's Nuclear Materials Technology Program, several DOE/ NNSA and DOE EM facilities, and British Nuclear Fuels Limited.
Just this week, Lab researchers produced the first plutonium storage container of the DOE 3013 Campaign. Plutonium was welded into a can that meets the requirements for long-term storage at the Westinghouse Savannah River Site (SRS).
The Lab is the first among the sites to accomplish the task. Yesterday, representatives from LLNL, DOE and British Nuclear Fuels Limited gathered at the Labï¿½s Plutonium Facility within the Superblock, to celebrate.
"This is a tremendous example of what a good working relationship can accomplish," said Joe Sefcik, program leader for the Nuclear Materials Technology Program (NMTP). Without the cooperative effort between the Lab, DOE-Oakland and Savannah River, we wouldn't be doing this right now.
"Through this process we will be able to move surplus plutonium that we just donï¿½t need to have here," Sefcik added.
Over the past two years, the NMTP team has worked to install a British Nuclear Fuels Limited (BNFL) Plutonium Packaging System (PuPS) into the Superblock and to qualify the system to meet DOE Standard 3013 and a separate list of SRS requirements that would allow for the "canning" of surplus plutonium for long term safe storage.
Other DOE sites at Los Alamos, SRS, Hanford and Rocky Flats are also required to process surplus plutonium for safe long-term storage. However, besides LLNL, two other DOE sites, the Rocky Flats Plant and the Hanford Operations, have been working to meet SRS requirements for storing plutonium at the South Carolina site. The Lab is the first facility in the team effort to satisfy the DOE Standard 3013 and the multiple SRS packaging requirements. The SRS requirements range from processing of the plutonium materials to make them safe for long term storage, to the quality of the can and closure welds.
The canned plutonium will be shipped from LLNL to the Savannah River Site for storage, where the plutonium will be eventually removed from the cans and either immobilized for safe underground disposal, or converted into mixed oxide fuel for nuclear reactors.
The Lab expects to begin shipping the plutonium cans sometime in late summer.
"This is a very gratifying achievement for everyone involved," said Karen Dodson, a pyrochemist in the Superblock and the leader in the Lab effort. "Not only have the Labï¿½s researchers worked together as a team to complete a very difficult job, but they have worked as a team with multiple sites."
"Quite a bit of effort is about to pay off."
The disposition of the plutonium stems from Defense Nuclear Facilities Safety Board Recommendation 94-1, recommending that DOE sites stabilize plutonium, especially residues, for long-term storage of up to 50 years. Shortly after this recommendation, the DOE complex along with contractor sites started work on a process for stabilizing the plutonium and storing it in cans that would be safe for long term storage of up to 50 years. Brent Ives of NMTP and Aundra Richards of DOE-OAK initiated the process of selecting a subcontractor for generating the design and delivery of a welding system that would be used for welding the plutonium within stainless steel cans.
Denver-based BNFL was chosen as the subcontractor for producing a welding system. The company completed the design and development of the process for laser welding the plutonium cans shut. Doug McAvoy and Joe Arluck, NMTP, led the installation effort in the Plutonium Facility, while GSE construction was responsible for installation of the ventilation and electrical systems required for operation of the welding system. Livermore researchers then worked alongside BNFL engineers and technicians to perfect the laser welding system.
DOE/NNSA/OAK then ran a Readiness Assessment to certify that the operations would be performed safely within the authorization basis for the Plutonium Facility. NMTP researchers worked closely with SRS technical managers to qualify the plutonium processing and canning for shipment and storage of the cans at SRS.
"The Lab is just one of the fish in this pond," said Dodson. "Everyone has worked together to help reach the ultimate goal: safe storage and disposition of our surplus plutonium."
The canning process consists of a small amount of stabilized plutonium oxide or other excess plutonium metal placed in a "convenience can," much the same size as an elongated coffee can. This can is then crimp-sealed or screw-sealed and placed inside a stainless steel inner can, then laser welded shut. The inner can is then placed in a third or outer can, which is also welded shut. Once completed the entire contraption resembles children's nesting cups.
"The canning process eliminates any organic materials that might react to produce unwanted gases in the package," Dodson said. In addition, the inner and outer cans are filled with helium that is used to check for any leaks.
Dodson described the efforts to meet the DOE-STD-3013 and SRS criteria as ï¿½an extensive process, with quite a system of checks and balances. However, we were always confident we would reach our goal."
Once the storage can set goes to Savannah River, researchers will use technology also developed at the Lab to blend the plutonium oxide powder with a ceramic material, granulate it, then press and bake it. The completed material resembles a hockey puck. These inert pucks immobilize the plutonium for long-term storage, and, ultimately, underground disposal.
"It's a great feeling to start working toward a goal, and then achieve it," said Dodson.
"This team should be commended," said James Davis, DOE-Oakland, of the collaborative effort. "Of all the facilities working together to accomplish this goal, it's nice to see one of the labs get under way."
Les Dutton of BNFL says credit must also go to the Lab. "Without LLNL, this whole thing would not have run as smoothly."
In addition to Dodson, the team members include Mark Bronson, David Riley, Kevin Silveira, Doug McAvoy, Joe Arluck, and Brent Ives, all of DNT's Nuclear Materials Technology Program; Aundra Richards, Jim Shakiba, and Gary Callihan of DOE-OAK; Les Dutton and John Wilcynski of BNFL-Denver; and Mike Critchley, Gary Farnworth, Steve Fisher and Iain Lever, of BNFL-United Kingdom.