Systems Analysis of D-T and D- 3 He FRC Power Plants J.F. Santarius, S.V. Ryzhkov †, C.N. Nguyen ‡, and G.A. Emmert University of Wisconsin L.C. Steinhauer University of Washington APS Division of Plasma Physics Meeting November 15, 1999 † Present address: Baumann Moscow State Technical University ‡ Present address: Lehigh University

University of WisconsinJFS 1999 Abstract* † Field-Reversed Configuration (FRC) fusion power plants have been analyzed at the systems level using the University of Wisconsin’s zero-dimensional, profile-averaged WISC code. Although the cost of electricity remains the key figure of merit, some cases aimed primarily at high power density are presented. Confinement, power density, and other issues for D- 3 He power plants are discussed. Trade-offs are examined and a comparison made of D-T and D- 3 He FRC power plants. * Research funded by the DOE Office of Fusion Energy Sciences, the University of Wisconsin, and the Russian President’s Foundation. † Poster available at

University of WisconsinJFS 1999 Potential FRC Power Plant Applications

University of WisconsinJFS 1999 FRC’s Possess Significant Advantages   1  Extremely high fusion power densities available due to  2 B 4 scaling.   1  Extremely high fusion power densities available due to  2 B 4 scaling. No tokamak-like disruptions.No tokamak-like disruptions. Transport losses cross separatrix and then flow out along axis.Transport losses cross separatrix and then flow out along axis. Magnetic fields on power-plant coils 3--4 times lower than in tokamaksMagnetic fields on power-plant coils 3--4 times lower than in tokamaks Cylindrical geometry facilitates design and maintenance.Cylindrical geometry facilitates design and maintenance.

University of WisconsinJFS 1999 D- 3 He Fuel Could Make Good Use of the High Power Density Capability of FRC’s  D-T fueled innovative concepts become limited by first- wall neutron or surface heat loads well before they reach  or B-field limits.  D-T fueled FRC’s optimize at B  3 T.  D- 3 He needs a factor of ~80 above D-T fusion power densities.  Fusion power density scales as  2 B 4.  Superconducting magnets can reach at least 20 T.  Potential power-density improvement by increasing B-field to limits is (20/3)^4 ~ 2000; far more than required.

University of WisconsinJFS 1999 Reduced D- 3 He Neutron Production Relaxes Engineering Constraints  Radiation shield thickness can be smaller by factor of ~2.  Low radiation damage in D- 3 He fusion core allows permanent first walls and structure.  D- 3 He power plant waste can be hospital-level (Class A) using low-activation steel.  Increased charged-particle flux allows efficient direct energy conversion.

University of WisconsinJFS 1999 D- 3 He Fuel Requires High Beta, n , and T T and n  must each be 4 to 5 times higher. T and n  must each be 4 to 5 times higher. Power density in the plasma must be increased using  2 B 4 scaling. Power density in the plasma must be increased using  2 B 4 scaling.

University of WisconsinJFS 1999 FRC Geometry Nearly Eliminates the Tokamak Disruption Problem  MHD tilt instability, probably the closest FRC analogue to a tokamak disruption, will send the plasma along the axis and into the end chamber, where measures can be more easily taken to mitigate and localize the effects.  Steady-state heat flux is broadly spread and due almost exclusively to bremsstrahlung radiation power.  Edge region vacuum pumps well and should shield the core plasma from most impurities.

University of WisconsinJFS 1999 FRC Plasma Power Flows Differ Significantly from Tokamak Power Flows  Power density can be very high due to  2 B 4 scaling, but this does not necessarily imply an unmanageable first-wall heat flux.  Charged-particle power transports from internal plasmoid to edge region and then out ends of fusion core.  Expanded flux tube in end chamber reduces heat and particle fluxes, so charged-particle transport power only slightly impacts the first wall.  Mainly bremsstrahlung power contributes to first-wall surface heat.  Relatively small peaking factor along axis for bremsstrahlung and neutrons.

Linear Geometry Greatly Facilitates Engineering  Flow of charged particles to end plate reduces first-wall surface heat flux.  Modules containing blanket, shield, and magnet can be replaced as single units due to their moderate mass.  Maintenance should be easier and improve reliability and availability.  Considerable flexibility exists for placement of pipes, manifolds, etc.  Direct conversion of transport power to electricity could increase net efficiency. University of Wisconsin JFS 1999

University of WisconsinJFS 1999 FRC Magnets Fit Well within Superconducting State-of-the-Art  Magnetic fields for both D-T and D- 3 He FRC power-plant coils are usually projected to be <6 T.  Externally generated field within fusion core nearly equals the field on the coils  increased power density (B 4 ).  MHD pressure drop for liquid-metal coolants will require less pumping power than in tokamaks.  High-temperature superconductors presently operate at relevant current densities at 5 T in short lengths.  High-temperature superconductors should be more resistant to quenching and thus may reduce the required radiation shield.

University of WisconsinJFS 1999 D-T FRC Engineering Scoping Study Key Assumptions  Rotating magnetic field (RMF) current drive.  Steady-state operation.  He/Li 2 0/SiC for coolant/breeder/structure of first wall and blanket.  Superconducting magnets, possibly high-Tc.  Thermal energy conversion only.  Horizontal (radial) maintenance of blanket/shield/magnet modules (~5 m length).  ARIES economic model assumptions.

University of WisconsinJFS 1999 FRC Plasma and Plant Power Flow

Preliminary † Plasma Parameters University of Wisconsin JFS 1999 † Not fully optimized and code still being benchmarked.

Preliminary † Engineering Parameters University of Wisconsin JFS 1999 † Not fully optimized and code still being benchmarked.

University of WisconsinJFS 1999 Proliferation-Resistant FRC Power Plant May Be Possible (Probably Requires D- 3 He)

University of WisconsinJFS 1999 Liquid-Walled FRC Power Plants Might Achieve Extremely High Power Densities  The APEX study uses the FRC as a key alternate to the tokamak.  Thick liquid walls (e.g., Li, Flibe, LiPb, LiSn) would attenuate neutrons and serve as  Tritium breeder  Radiation shield  Heat transfer medium

University of WisconsinJFS 1999 D- 3 He and High Beta Will Lower Development Costs

University of WisconsinJFS 1999Conclusions  From a fusion energy development perspective, FRC’s occupy the important position of leading the  -driven, engineering-attractiveness route.  The cylindrical geometry and disruption-free operation of D-T FRC’s should allow them to overcome the major engineering obstacles facing D-T tokamaks.  FRC’s match D- 3 He fuel well, and the combination potentially could outperform D-T.