Publications

Due to increasing concerns over the buildup of long-lived transuranic isotopes in spent nuclear fuel waste, attention has been given in recent years to technologies that can burn up these species. The separation and transmutation of transuranics is part of a solution to decreasing the volume and heat load of nuclear waste significantly to increase the repository capacity. A fusion neutron source can be used for transmutation as an alternative to fast reactor systems. Sandia National Laboratories is investigating the use of a Z-Pinch fusion driver for this application. This report summarizes the initial design and engineering issues of this ''In-Zinerator'' concept. Relatively modest fusion requirements on the order of 20 MW can be used to drive a sub-critical, actinide-bearing, fluid blanket. The fluid fuel eliminates the need for expensive fuel fabrication and allows for continuous refueling and removal of fission products. This reactor has the capability of burning up 1,280 kg of actinides per year while at the same time producing 3,000 MWth. The report discusses the baseline design, engineering issues, modeling results, safety issues, and fuel cycle impact.

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This report summarizes the work conducted for the Z-inertial fusion energy (Z-IFE) late start Laboratory Directed Research Project. A major area of focus was on creating a roadmap to a z-pinch driven fusion power plant. The roadmap ties ZIFE into the Global Nuclear Energy Partnership (GNEP) initiative through the use of high energy fusion neutrons to burn the actinides of spent fuel waste. Transmutation presents a near term use for Z-IFE technology and will aid in paving the path to fusion energy. The work this year continued to develop the science and engineering needed to support the Z-IFE roadmap. This included plant system and driver cost estimates, recyclable transmission line studies, flibe characterization, reaction chamber design, and shock mitigation techniques.

The Z-Pinch fusion experiment at Sandia National Laboratories has been making significant progress in developing a high-energy fusion neutron source. This source has the potential to be used for the transmutation of nuclear waste. The goal of this research was to do a scoping-level design of a fusion-based transmuter to determine potential transmutation rates along with the fusion yield requirements. Two ''In-Zinerator'' designs have been developed to transmute the long-lived actinides that dominate the heat production in spent fuel. The first design burns up all transuranics (TRU) in spent fuel (Np, Pu, Am, Cm), and the second is focused only on burning up Am and Cm. The TRU In-Zinerator is designed for a fuel cycle requiring burners to get rid of all the TRU with no light water reactor (LWR) recycle. The Am/Cm In-Zinerator is designed for a fuel cycle with Np/Pu recycling in LWRs. Both types of In-Zinerators operate with a moderate fusion source driving a sub-critical actinide blanket. The neutron multiplication is 30, so a great deal of energy is produced in the blanket. With the design goal of generating 3,000 MW{sub th}, about 1,200 kg/yr of actinides can be destroyed in each In-Zinerator. Each TRU In-Zinerator will require a 20 MW fusion source, and it will take a total of 20 units (each producing 3,000 MWth) to burn up the TRU as fast as the current LWR fleet can produce it. Each Am/Cm In-Zinerator will require a 24 MW fusion source, and it will take a total of 2 units to burn up the Am/Cm as fast as the current LWR fleet can produce it. The necessary fusion yield could be achieved using a 200-240 MJ target fired once every 10 seconds.

Recent interest in reprocessing nuclear fuel in the U.S. has led to advanced separations processes that employ continuous processing and multiple extraction steps. These advanced plants will need to be designed with state-of-the-art instrumentation for materials accountancy and control. This research examines the current and upcoming instrumentation for nuclear materials accountancy for those most suited to the reprocessing environment. Though this topic has received attention time and again in the past, new technologies and changing world conditions require a renewed look and this subject. The needs for the advanced UREX+ separations concept are first identified, and then a literature review of current and upcoming measuring techniques is presented. The report concludes with a preliminary list of recommended instruments and measurement locations.

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