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NMT Charters New Group for Pits

The Pit Disassembly and Surveillance Technologies Group, NMT-15, has been chartered to lead the United States with technological support of new and ongoing pit disassembly and surveillance campaigns. Several technological support areas comprise this group, which includes the following major research projects:

(1) Advanced Recovery and Integrated Extraction System (ARIES),
(2) Pit Disassembly and Conversion Facility (PDCF),
(3) US-Russian collaborations to reduce the global nuclear danger,
(4) Pit Surveillance, Surveillance Information Systems (SIS), and enhanced surveillance,
(5) Special Recovery Line (SRL), and
(6) Electrolytic decontamination technologies.

These projects are described briefly below.

Figure 1. ARIES hydride/dehydride furnace during cold testing.

Advanced Recovery and Integrated Extraction System (ARIES)
The ARIES Demonstration Project consists of six modules-Pit Bisector, Hydride-Dehydride-Recycle, Direct Metal Oxidation, Canning, Electrolytic Decontamination and Packaging, and Nondestructive Assay-with a remotely controlled conveyor system to move material between the modules.

After receiving approval from LANL's Plutonium Facility management, the Department of Energy, and several independent readiness review committees, the ARIES Team conducted "hot" start-up activities between November 1998 and July 1999. Some procedural and equipment modifications were subsequently made. The initial ARIES "production" demonstration to process pits within three months began in July 1999. By mid-August, the demonstration was 50% complete; it included processing at least one of each of the proposed seven surplus pit types.

Research under the ARIES project includes electrochemistry, new and improved engineering techniques, plutonium interactions with other elements, materials science engineering, process controls, various nondestructive assay measurements, dose collection, and robotics. All of the research development and demonstrations support the DOE Office of Fissile Materials Disposition program for surplus plutonium disposition.

Pit Disassembly and Conversion Facility (PDCF)
Interactions between Los Alamos National Laboratory, Westinghouse-Savannah River (the preferred alternative site pending the Record of Decision for the PDCF), and Raytheon (the design firm) are underway to transfer ARIES technology in support of the full-scale production plant. Working closely with Westinghouse personnel should assure a strong, site-specific scope of work, well-defined roles and responsibilities, development of a technically feasible facility demonstration document, as well as workable Title I (cost estimate) and Title II (detailed cost estimate) designs. While funding is available for the design, Congressional language states that funds for the construction of the PDCF are contingent upon Russia's progress on the disposition of her nuclear weapons. Success of the US program, therefore, is dependent on success of the Russian program. Research activities include new and improved design/engineering techniques for the disassembly and conversion of all types of nuclear weapons.

US-Russian Collaborations
US collaborations with the Russian Federation continue with cooperative research and development of technologies to convert weapons-origin plutonium to a suitable form of mixed oxide (MOX) fuel for light-water reactors. Since the nondestructive assay system is the same for the US and Russia, it is an integral component of pit conversion and could be used to support independent verification through bilateral or international agreements on the dismantlement of nuclear weapons. The current economic situation in Russia threatens to retard or halt progress without international support; thus, the US is funding significant disposition efforts in Russia.

Figure 2. Senator Pete Domenici (second from left) tours the ARIES NDA system.

Los Alamos is the lead national laboratory for Russian collaborations on technologies to disassemble nuclear weapons and convert the extracted plutonium into MOX fuel or other unclassified forms suitable for international inspection. In order to understand the Russian process for developing facilities, NMT-15 is conducting a series of workshops on design, licensing, constructing, and commissioning of nuclear facilities. The product of this effort is a flow sheet showing the logic of the Russian process compared to that of the US. These workshops will also generate a generic schedule to serve as the starting point for preparing a more specific schedule for the Russian PDCF. The end of 1999 is the target for the completed current efforts and a preliminary feasibility study, followed by selection of a conversion process.

Pit Surveillance Program (PSP) and Stockpile Information Services (SIS)
The PSP supports the surveillance of pits (evaluation and shelf life) as well as the SIS. The PSP is responsible for monitoring, detecting, and addressing potential problems within weapon systems. The SIS project is responsible for providing PSP pit engineers, material scientists, and customers throughout the DOE/DP complex with information on nuclear weapon pit production, the stockpile, and experimental records. Weighing, photography, gas sampling, leak checking, radiography, eddy current testing (nondestructive tests using electrical current to help determine if there are gaps between materials), ultrasonic testing (nondestructive tests using sound waves to determine if there are gaps between materials), and acoustic resonance spectroscopy are some analyses performed on pits selected for destructive evaluation or disassembly. Some pits are held in the shelf-life program. These pits are used for trend analysis of gas data. Some nondestructive testing will be performed on war reserve or "rebuild" units once their production begins at TA-55. Metallography, chemistry, hydriding-dehydriding of residues, and surface analyses are performed in a timely manner as part of the evaluation process. The final analyses result in the generation and publication of pit evaluation reports for completed disassemblies, as well as those in the "rebuild" program. Some shelf-life units are also disassembled for evaluation.

Figure 3. Pit bisector used to cut pits in half. This instrument was developed in collaboration with Lawrence Livermore National Laboratory.

Special Recovery Line (SRL)
The SRL is chartered with decontaminating tritium from plutonium. This process line represents a one-of-a-kind capability within the DOE complex. Research activities include new and improved engineering techniques, characterization of tritium-plutonium interactions, and other materials science engineering.

Electrolytic Decontamination for Glove Boxes and Packaging Highly Enriched Uranium
Electrolytic Decontamination (EDC) is the process for removing radioactive contamination from surfaces. The EDC process used here represents the only operating system in the US for packaging plutonium metal or plutonium oxide to meet the DOE-STD-3013-96 packaging criteria. Research in the packaging activity includes electrochemistry, engineering development of packages, welding, process controls, fluid handling, and robotics.

The baseline technology within the DOE complex for removing plutonium contamination from the surface of highly enriched uranium is EDC, which leads to the disposition of the material at Y-12. Research activities include alpha-spectroscopy techniques, electrochemistry, and engineering.

Decontaminating transuranic-waste-level items to low-level waste items leads to great cost savings and reduces potential radioactive contamination exposures. In situ glove box decontamination using EDC methods is resulting in low levels of contamination. Research activities include electrochemistry and engineering.

The new NMT-15 Group Leader Tim Nelson contributed this article.


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