Program Address Plutonium Pit Conversion in Russia

Figure 1. Roundtable discussion of the joint US/Russian nondestructive assay team.

The Russian Federation is dismantling its nuclear weapons and plans to convert the plutonium pits into a form that is suitable for mixed-oxide (MOX) fuel fabrication. The United States, through the Department of Energy (DOE), working with the Los Alamos National Laboratory, is studying plutonium conversion technologies as part of its own disposition plan. Los Alamos has also been tasked by DOE to lead a concurrent effort with the Russians on plutonium conversion. This article will discuss the plan for the US-Russian cooperative activities for the conversion of weapons-origin plutonium in Russia.

The joint US-Russian program for pit conversion is divided into the following three major activities: 1) cooperative research and development; 2) nondestructive assay (NDA) and material protection, control and accountability (MPC&A); and 3) the Pit Conversion Pilot Plant Demonstration. The first activity includes the cooperative research and development of technologies to convert weapons-origin plutonium to a suitable form for MOX fuel fabrication.

Conversion technologies being considered are the following:

• Pyrochemical conversion (hydride/oxidation),
• Aqueous conversion,
• Combined conversion (pyrochemical/ aqueous technologies), and
• Pyroelectrochemical conversion (molten salt).

In addition, support technologies being considered are the following:

• Storage requirements for oxide, container development, and transportation requirements;
• Comparison of oxides for MOX fuel produced by the above conversion technologies; and
• Radiation and nuclear safety analysis.

Figure 2. The joint US/Russian committee for plutonium disposition poses for a picture after their tour of the ARIES (Advanced Recovery and Integrated Extraction System) and MOX (mixed-oxide) facilities in Building PF-4.

The NDA/MPC&A process is an integral component of pit conversion. It ensures material accountability for the conversion line and initiates material accountability for storage and subsequent operations. The NDA system for the plutonium conversion could be used to support independent verification through bilateral or international agreements on the dismantlement of nuclear weapon pits. This set of activities will include developing an NDA system for the Russian Pilot Demonstration Line; developing an MPC&A system for the line; integrating the NDA system with the Line; and forging agreements with International Atomic Energy Agency (IAEA) regarding this approach to material analysis. These activities are similar to US efforts with IAEA toward the US NDA system. The Russian NDA system will be very similar in concept and function to the US system, facilitating agreement on each nation's material measurements.

The Pit Conversion Pilot Plant Demonstration will include the design, construction, and operation of a pilot demonstration line in Russia for conversion of surplus, weapon-origin plutonium ingots to oxide. As presently conceived, the line will have as its input the metal ingots from earlier processing in which the plutonium was removed from surplus nuclear weapons components and melted into ingots of unclassified shape and mass. The pilot line will convert the ingots into plutonium oxide of suitable quality for fabrication into MOX fuel or for other disposition options.

Figure 3. Teresa Cremers(NMT-4) reviews the circuit board provided by her counterparts in Russia who perform nondestructive assay. The circuit board was tested for performance and compatibility with US equipment.

Significant accomplishments for the program to date are the following:

• Signing of a contract with the A. A. Bochvar All-Russian Institute in Inorganic Materials (VNIINM) to prepare a master plan outlining the required steps for determining the optimum conversion process for weapons-origin plutonium metal into oxide that can be used to produce MOX fuel. The master plan has been approved by both the Los Alamos National Laboratory and VNIINM.
• Signing of a contract (initial phase) with VNIINM to develop and implement an NDA system for accounting and control of nuclear materials. Representatives of Russia visited Los Alamos in October 1997 under this contract to test and evaluate Russian gamma ray spectroscopy hardware for use in the Russian NDA system.
• Signing of a contract (initial phase) with VNIINM to develop technologies needed to determine the optimum conversion process for weapons-origin plutonium metal into oxide that can be used to produce MOX fuel.
• Signing of a contract with the Russian State Specialized Design Institute (GSPI) to perform a feasibility study, data-gathering, and preparation tasks for conversion of weapons-origin plutonium metal into oxide that can be used to produce MOX fuel. This was accomplished by GSPI in May 1998.

This article was contributed by Warren T. Wood (NMT-6) and Edouard M. Glagovsky (State Scientific Center of Russian Federation, A. A. Bochvar All-Russian Research Institute of Inorganic Materials, Moscow, Russia)

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