Fusion transmutation of waste and the role of the In-Zinerator in the nuclear fuel cycle.

Abstract

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 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.4

Burning high-level TRU waste in fusion fission reactors

“…For example, Hyland et al proposed MA burning in LWR or CANDU; 2,3 Forsberg et al proposed molten salt reactors (MSRs, liquid-fueled reactors) can be used for burning actinides; 4 Hejzlar et al proposed actinide burning in a leadbismuth-cooled critical fast reactor (LFR); 5 and Sandia National Laboratories designed a Z-pinch fusion driver for the transmutation of TRU. 6 In this paper, we propose a new concept of actinide burning with a thorium-uranium (Th-U) cycle with an external fusion neutron source (14.1 MeV). Such a fusion-fission reactor (FFR) can be driven by various external neutron sources, such as ITER, Z-Pinch, ICF or even ADS.…”

“…Table 1 shows the TRU properties of regular LWR spent fuel; the atomic fraction of TRU is taken from the Ref. 6. Here, Pu is more than 80%, Am is about 11%, Np is about 7% and Cm is less than 1%.…”

Z-inertial fusion energy: power plant final report FY 2006.

“…This will allow a single repository, Yucca Mountain, to store all of the remaining spent fuel waste up into the next century [4]. Z-pinch driven IFE technology offers several advantages over fast reactors for burning the actinides which is discussed in more detail in a report on z-pinch transmutation [5]. As mentioned above the ultimate goal of creating this roadmap was to show how Z-IFE can be included in the GNEP initiative.…”

“…The current Z-IFE design uses flibe to breed tritium. The proposed process for extracting the tritium from flibe is explained in the Z-IFE transmutation report [5]. This section focuses on minimizing tritium permeation from the chamber and the process piping.…”

“…Due to the possibility of using aerosols to mitigate the x-rays, a first wall chamber design was proposed. This concept was first developed to be used for the transmutation plant where target yield requirements were much less compared to what was required from the power plant [5]. However, results from the computer modeling described in section 4.1.7 indicate that aerosols may be able to mitigate fusion yields upward to 3 GJ (~1000 MJ x-rays).…”