Transmutation of Waste Using Z-Pinch Fusion

1. Transmutation of Waste Using Z-Pinch Fusion October 1, 2009 Ben Cipiti & Gary Rochau V.D. Cleary1, J.T. Cook1, S. Durbin1, R.L. Keith1, T.A. Mehlhorn1, C.W. Morrow1, C.L. Olson1, G.E. Rochau1, J.D. Smith1, M. Turgeon1, M. Young1, L. El-Guebaly2, R. Grady2, P. Phruksarojanakun2, I. Sviatoslavsky2, P. Wilson2, A.B. Alajo3, A. Guild-Bingham3, P. Tsvetkov3, M. Youssef4, W. Meier5, F. Venneri6, T.R. Johnson7, J.L. Willit7, T.E. Drennen8, W. Kamery8 1Sandia National Laboratories, Albuquerque, NM 2University of Wisconsin, Madison, WI 3Texas A&M University, College Station, TX 4University of California, Los Angeles, CA 5Lawrence Livermore National Laboratory, Livermore, CA 6General Atomics, San Diego, CA 7Argonne National Laboratory, Chicago, IL 8Hobart & William Smith College, Geneva, NY Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

2. Overview • The Z-Pinch Transmutation study was funding through LDRD funds from FY06-FY07, but the work builds off the Z-Pinch Power Plant Study. • Outline • Z-Pinch Facility • In-Zinerator Concept • Engineering Challenges • Transmutation Results 2

3. Z-Pinch Facility Z-Pinch Facility Fusion Target 3

4. Z-Pinch Operation • Marx generators deliver the pulse of power through water lines to a magnetically insulated transmission line (power plant would require linear transformer driver). • Past operation delivered 1.8 MJ of x-rays to the target in about 5 ns, but Z was recently upgraded, so future work may increase the power delivery. • Using deuterium gas targets, yields close to 4x1013 n per target have been achieved (D-D) ~ 1016 n per target D-T. 4

5. Sub-Critical Transmutation Blanket • An actinide blanket surrounds the Z-Pinch target to capture as many of the fusion neutrons as possible. • The actinides are contained in a fluid fuel, which is contained in an annular array of tube banks • Fusion neutrons are used to initiate fissioning of the actinides • A modest 20 MW fusion source is required • The actinide blanket produces 3000 MWth • This design burns down waste while at the same time producing a lot of power • A molten lead coolant is used to remove the heat from the actinide tubes and drive a power plant Transmission Lines Steam Generator Or IHX Heat Cycle Tin RTL Actinide Tubes Gas, Tritium & FP Removal Fusion Target Pump Aerosol Atmosphere Lead Coolant RTL & Target Debris 5

6. In-Zinerator Power Plant Transmission Lines Linear Transformer Driver Generator Electrical Power Li, AnF3 (LiF)2-AnF3 Gas Turbine Heat Exchanger Fuel Salt Reconstitution RTL Brayton Cycle I2, Xe, Kr Pump Fusion Target Hydrogen Getter Filters Continuous Extraction Actinide Tubes Gas Removal Waste Treatment 6

7. Chamber Design Number of Tubes: 19182 Pitch: 3.25 cm Tube ID: 2.0 cm Tube OD: 2.6 cm 4.06 m 3.36 2.15 2.05 4.09 m 2 Fuel Region 1.21 m thick Coolant 6 m Argon Atmosphere 10 torr Chamber Ends 0.2 m thick 7

8. In-Zinerator Conceptual Design Parameters Blanket Actinide Mixture (LiF)2-AnF3 Coolant Lead Coolant Configuration Shell & Tube First Wall Configuration Structural Wall Shock Mitigation Argon gas & aerosol Coolant Temperature 950 K Heat Cycle Rankine or Brayton Number of Fuel Tubes 19182 Extraction Systems Tritium Breeding Ratio 1.1 Tritium production 3.8 g/day Fission Product Removal On-Line Removal Overall Parameters Fusion Target Yield 200 MJ Repetition Rate 0.1 Hz Keff 0.97 Power per Chamber 3,000 MWth Energy Multiplication 150 Transmutation Rate 1,280 kg/yr Number of Chambers 1 RTL & Target RTL Material Tin (or Steel) RTL Cone Dimensions 1m Ø x 0.1m Ø x 1m H Mass per RTL 67 kg (Tin) Tritium per Target 1.35 mg Chamber Design Shape Cylindrical Dimension 4.1 m outer radius Chamber Material Hastelloy-N Wall Thickness 5 cm 8

9. Engineering Issues • First Wall Z-Pinch offers a unique ability to use aerosol sprays in the chamber to attenuate x-rays—this protects the first wall from melting and is only possible because Z-Pinch does not require pristine chamber conditions • Radiation Damage Initial designs had unacceptable radiation damage to the inner chamber wall and actinide tubes. Design changes such as inserting a standoff between the first wall and actinide tubes reduced the maximum dpa to below 50 dpa for all tubes and below 40 dpa for the first wall. • Energy Deposition in the Fuel The fusion and subsequent fission neutron pulse occurs almost instantaneously, resulting in nearly instantaneous energy deposition. The peak temperature rise in the fuel was 150 °C per shot, but further optimization is required to bring this number down. • Actinide Mixture (LiF)2-AnF3 was chosen for its high actinide solubility, ability to breed tritium, somewhat reasonable melting temperature, and non-reactive composition. Unfortunately thermodynamic properties of the material are not known well. 9

10. Recyclable Transmission Line Engineering Issues • Tin RTL Structural Analysis A low melting temperature material like tin may make for a good RTL due to the ease of production and collection. RTL fragments in the chamber will melt and can be collected at the bottom. • RTL Cost The In-Zinerator concept requires one RTL every ten seconds. Steel RTL: $5.40 per RTL or $1.94 per MWh Tin RTL: $1.20 per RTL or $0.44 per MWh (Total fuel cost for nuclear reactors is about $5.50 per MWh) 10

11. Bi-AM Bi-AM Bi-AM Low Temp Charcoal Filter Adsorber High Temp Charcoal Filter Adsorber He, H, T, Kr, Xe He, H, T, Kr, Xe HX HX Zirconium Extraction Actinide Extraction RE-AE-AM Extraction Salt Salt Salt He, H, T H, T N2 H2O LN2 He, Br, I, Kr, Xe, H, T HX Salt from Reactor Multi-stage HX Hydrogen Getter BiF3 Formation N2 He Salt– BiF3 (LiF)2-AnF3 @ 44 Kg/min He/H2 (from distillation) Sparge Tube(s) Bi-Zr-Am Bi-Am-Cm Bi-RE-AE-AM Bi Salt to Reactor F2 Salt Zirconium Scrub Actinide Strip Salt– BiF3 Salt – Am-Cm Salt– BiF3 Salt Electrolysis Bi Bi-AM Fuel Salt Reconstitution Bi Recycle Waste Treatment Bi-Zr Wasteform Makeup LiF-AmF3-CmF3 RE = rare earths; AE = alkaline earths; AM = alkali metals Extraction Systems • Design of Extraction Systems A preliminary design of the continuous fission product and tritium extraction systems has been completed. Tritium Recovery Fission Product Separation 11

12. Modeling • MCNP was used to optimize the baseline design to reach the desired keff, power level, chamber size, tritium breeding, etc. • MCise was used to calculate time dependent burnup rates, fission product production, and isotopic change • ORIGEN was used to then calculate the activity and heat load to determine the net effectiveness of transmutation 12

13. In-Zinerator Isotope Ratio Change with Time (TRU Burner) 13

14. 1280 kg/yr TRU Burned at 20 MW Fusion Driver and 3000 MW Total Power 14

15. A Heat Load Reduction by a Factor of 100 is Seen after 200 Years 15

16. Z-Pinch Technology Roadmap Radiation Effects Testing Transmutation Demo on ZN Facility Full Scale In-Zinerator Fusion Energy Breakeven? High Yield ZR ZN Transmutation Energy 2010 2020 2030 2040 2050 Demonstrate Shock Mitigation Demonstrate RTL & Chamber Sealing Demonstrate LTD Driver Demonstrate Target & RTLPlant Demonstrate Tritium Containment Demonstrate Moderate Rep Rate Install Transmutation Blanket 16