SABR SUBCRITICAL ADVANCED BURNER REACTOR

1. SABRSUBCRITICAL ADVANCED BURNER REACTOR W. M. STACEY Georgia Tech FPA Symposium, Washington December, 2009

2. RATIONALE FOR FUSION-FISSION HYBRIDS EXPANDING NUCLEAR POWER • Global expansion of carbon-free nuclear power is the most (only?) technically realistic near-term way to prevent further environmental degradation (global warming) But • The present “open” nuclear fuel cycle is not sustainable: i) spent nuclear fuel is accumulating in temporary storage facilities and ii) we would run out of fuel before the end of the century. However • Fusion-Fission Hybrids could help (may be necessary?) to enable a “closed”, sustainable nuclear fuel cycle. Subcritical Advanced Burner Reactor

3. SPENT NUCLEAR FUEL • Spent nuclear fuel consists of uranium, TRU (transuranic actinides) and fission products. • The capacity of a geological repository is determined by the decay heat load, which after 100 years is determined by the TRU. • All of the TRU actinides are fissionable by fast neutrons. Subcritical Advanced Burner Reactor

4. A SOLUTION FOR THE SPENT FUEL PROBLEM • Separate the fission products, uranium and TRU. • Store the uranium, pending future transmutation into plutonium fuel for reactors. • Fission the TRU as fuel in fast reactors. • Send the fission products for storage in a geological repository, which would be sealed after 100 years cooling. • Since the repository heat load per reactor spent fuel discharge has been reduced, the number of geological repositories required has also been reduced (factor of 10). Subcritical Advanced Burner Reactor

5. TRU-FUELED FAST REACTORS • In the near-term, fast “burner” reactors to reduce and stabilize the TRU inventory from LWR SNF. • In the intermediate term, fast “breeder” reactors to produce plutonium from U238 to fuel advanced LWRs. • In the longer term, self-sustaining fast “power” reactors that produced their own fuel from U238. Subcritical Advanced Burner Reactor

6. SUBCRITICAL OPERATION OF TRU-FUELED FAST BURNER REACTORS IS FAVORED • In a critical reactor, the reactivity safety margin to prompt critical is the delayed neutron fraction, b, which is a factor of 2-3 smaller for TRU fuel than for uranium fuel. For subcritical operation, this reactivity safety margin is much larger = b + ∆ksub . • In a subcritical reactor, the neutron source strength can be increased to maintain the reactor power level as the reactivity decreases with fuel burnup, enabling the fuel to remain in the reactor for a “deep burn” until the radiation damage limit. Subcritical Advanced Burner Reactor

7. A F-F HYBRID BASED ON ITER PHYSICS & TECHNOLOGY AND ON NA-COOLED FAST REACTOR & SEPARATIONS TECHNOLOGY • A large world-wide R&D effort is supporting the leading Na-cooled fast reactor and associated separation technologies. Several Na-cooled fast reactors will soon be operating. There is discussion of industrial facilities being deployed over about 2030-2080. • A large worldwide R&D effort is supporting the leading tokamak magnetic fusion concept, and ITER will protoype the fusion physics and technology needed for a hybrid over 2018-2032, although high reliability, steady-state operation also must be achieved. • Studies have been performed at Georgia Tech to evaluate combining ITER fusion physics and technology with Na-cooled, metal-fuel fast burner reactor technology to design the SABR fusion-fission hybrid fast burner reactor. Subcritical Advanced Burner Reactor

8. SUB-CRITICAL ADVANCED BURNER REACTOR (SABR) • ANNULAR FAST REACTOR (3000 MWth) 1. Fuel—TRU from spent nuclear fuel. TRU-Zr metal being developed by ANL. 2. Sodium cooled, loop-type fast reactor. • Based on fast reactor designs being developed by ANL in DoE Nuclear Program. • TOKAMAK D-T FUSION NEUTRON SOURCE (200-500 MWth) 1. Based on ITER plasma physics and fusion technology. 2. Tritium self-sufficient (Li4SiO4). 3. Sodium cooled. Subcritical Advanced Burner Reactor

9. LiNbO3 t=0.3 mm Fuel R=2 mm ODS Clad t=0.5 mm Na Gap t=0.83 mm FUEL Axial View of Fuel Pin Composition 40Zr-10Am-10Np-40Pu (w/o) (Under development at ANL) Design Parameters of Fuel Pin and Assembly Cross-Sectional View Fuel Assembly Subcritical Advanced Burner Reactor

10. 4-BATCH FUEL CYCLE • Fuel cycle constrained by 200 dpa clad radiation damage lifetime. 4 (700 fpd) burn cycles per residence • OUT-to-IN fuel shuffling, ERANOS nuclear calculation • BOL keff = 0.972, Pfus = 75MW, 32 MT TRU • BOC keff = 0.894, Pfus = 240MW, 29 MT TRU • EOC keff = 0.868, Pfus = 370MW, 27 MT TRU • 24% TRU burnup per 4-batch residence, >>90% with repeated recycling • 1.05 MT TRU/FPY fissioned • Supports 3.0 1000 MWe LWRs (0.25 MT TRU/yr) at 76% availability during operation (2 mo refueling). SABR TRU FUEL COMPOSITION (w/o) ANNULAR CORE CONFIGURATION Subcritical Advanced Burner Reactor

11. Neutron Source Design Parameters SABR TOKAMAK NEUTRON SOURCE PARAMETERS Subcritical Advanced Burner Reactor

12. ADAPTED ITER NEUTRON SOURCE TECHNOLOGY • Six 20 MW ITER LHR launchers. • Adapted ITER FW and divertor for Na and He coolant. Replaced SS with ODS steel. Confirmed heat removal with FLUENT code. • FW lifetime 6.5 FPY at 200 dpa. Replace every 3rd refueling shutdown. • Scaled down ITER SC CS and TF magnet designs, maintaining ITER standards. • Multilayer shield. MCNP and EVENT predict > 30 FPY (40 yrs @ 75% avail) radiation damage lifetime for SC magnets. Subcritical Advanced Burner Reactor

13. Li4SiO4 Tritium Breeding Blanket 15 cm Thick Blanket Around Plasma (Natural LI) and Reactor Core (90% Enriched LI) Achieves TBR = 1.16. NA-Cooled to Operate in the Temperature Window 420-640 C. Online Tritium Removal by He Purge Gas System. Dynamic ERANOS Tritium Inventory Calculations for 700 d Burn Cycle, 60 d Refueling Indicated More Than Adequate Tritium Production. Subcritical Advanced Burner Reactor

14. R&D FOR A TOKAMAK FFH NEUTRON SOURCE IS ON THE PATH TO PURE FUSION ELECTRIC POWER FUSION R&D FOR A TOKAMAK F-F HYBRID • Ongoing worldwide tokamak physics R&D program, including ITER-specific issues (e.g. ELM suppression, startup scenarios). • ITER construction and operation experience-- prototype. • Physics R&D on reliable steady-state, disruption-free operation, burn control, etc. • Plasma Support Technology (magnets, heating systems, etc.) R&D for component reliability. • Remote Maintenance. • Fusion Nuclear Technology (tritium breeding, etc.) R&D • Advanced Structural Materials (200 dpa) R&D FURTHER FUSION R&D FOR TOKAMAK ELECTRIC POWER 8. Advanced confinement and pressure limits physics R&D. 9. Advanced DEMO. Subcritical Advanced Burner Reactor

15. CONCLUSIONS • The physics and technology performance parameters of ITER (many of which have been achieved already) will be more than adequate for a fusion neutron source for a FFH fast burner reactor. ITER will be the prototype. • Additional R&D will be needed to obtain greater component and plasma reliability than demanded of ITER, tritium breeding technology, and a more radiation resistant structural material. • The physics performance parameters and FW neutron and heat loads for a FFH are significantly less than are required for pure fusion electric power. • The feasibility of deployment of a tokamak fusion neutron source, based on ITER physics and technology, in a FFH fast burner reactor by about 2040 is compatible with the nuclear power scenario for deploying transmutation reactors over roughly 2030-2080. • Thus, FFH transmutation reactors (for the fissioning of the transuranics in discharged LWR fuel and hence the reduction of geological waste repository requirements) would seem to be the target of opportunity for fusion to contribute to solving the world’s energy problems starting in the first half of the present century. Subcritical Advanced Burner Reactor

16. R-Z Cross section SABR calculation model Subcritical Advanced Burner Reactor