Sodium-Cooled Fast Reactor

1. Sodium-Cooled Fast Reactor Final Design Report: SFR Design for TRU Recycling Fynan, Mar, Sirajuddin

2. Purpose • The open LWR fuel cycle produces 2000 MgHM/year. • The transuranics in the LWR spent fuel represent a significant legacy burden to future generations • The SFR represents a viable option to permanently transmute these transuranics into stable isotopes, while providing useful electric energy Fynan, Mar, Sirajuddin

3. Core Specifications • 840 MWth power rating • 310 day cycle length with 85% capacity factor • 46cm active core height • 4m core diameter • Variable driver fuel composition Fynan, Mar, Sirajuddin

4. Core Layout Fynan, Mar, Sirajuddin

5. Fuel Selections • Weapons Grade Plutonium (94% Pu-239) • WGPU • Reactor Grade Plutonium (60% Pu-239) • RGPU • Recycled Light Water Spent Fuel (51% Pu-239, 24% Pu-240, 6% Am, 4% Np) • RCLW • Minor Actinide Enriched (29% Pu-239, 13% Pu-240, 28% Am, 19% Np) • MAE Fynan, Mar, Sirajuddin

6. Proliferation Concerns • Pure thorium host fuel yields 95% U-233 enrichment • 25% natural uranium doping in host fuel denatures the U-233 enrichment below 12% Fynan, Mar, Sirajuddin

7. Transuranic Depletion Fynan, Mar, Sirajuddin

8. Introduction of burnable poisons into the fuel increased reactivity swing Use of Burnable poisons was abandoned in application to reactivity swing reduction Burnable Poisons Fynan, Mar, Sirajuddin

9. Active Core Height Optimization • Active core height investigated to decrease reactivity swing • REBUS geometry input template modified: fuel height changed, all other axial zones held constant • Active core heights investigated: • 25 cm • 55 cm • 85 cm Fynan, Mar, Sirajuddin

10. Active Core Height Mod – Reactivity Swing • Reactivity swing decreased with increasing height • Increase in height  less leakage, colder spectrum  less fission • Decrease in height  more leakage, harder spectrum more fission • REBUS-3 convergence criterion turned on for criticality  keff = 1 at EOC • Increase in height  less enrichment with driver fuel  less change in keff • Decrease in height  more enrichment with driver fuel  larger change in keff Fynan, Mar, Sirajuddin

11. Active Core Height Mod - Transmutation • Decrease in core height increased transmutation • Shorter core height  harder spectrum = good for TRUs Fynan, Mar, Sirajuddin

12. Core Power • Core divided into: • 5 radial regions • 11 axial zones • Middle 5 axial zones = active core • Power distribution ~ flat at BOC • Axial Power = chopped • cosine, center peaked Fynan, Mar, Sirajuddin

13. Safety Analysis • Sodium void coefficient positive = overmoderated region • Doppler and volumetric expansion coefficient of fuels provide largely negative coefficients  safe operation • Positive contribution comes from middle region of core Fynan, Mar, Sirajuddin

14. Thermal Hydraulics Fynan, Mar, Sirajuddin

15. Thermal Hydraulics K of UO2 ~ 0.03 W/cm-oC Fynan, Mar, Sirajuddin

16. Economic Considerations • High Capital Cost • High Cost of Thorium • High Cost of Reprocessing Fynan, Mar, Sirajuddin

17. References • [1] R. N. HILL, D. C. WADE, J. R. LIAW, and E. K. FUJITA, “Physics Studies of Weapons Plutonium Disposition in the Integral Fast Reactor Closed Fuel Cycle,” Nucl. Sci. Eng., 121, 17-31 (1995). • [2] J. KANG and F. N. VON HIPPEL, “U-232 and the Proliferation-Resistance of U-233 in Spent Fuel,” Science & Global Security, 9, 1-32 (2001). • [3] D. SIRAJUDDIN, N. MAR, and D. FYNAN, “First Preliminary Report: Fuel Composition Analysis of a Sodium-Cooled Fast Reactor,” (2007). • Rebus3 for equilibrium cycle analysis • Argonne National Laboratory • MC2 for lattice physics calculations • Argonne National Laboratory Fynan, Mar, Sirajuddin

18. … • Questions? Fynan, Mar, Sirajuddin