THE ARIES-I TOKAMAK REACTOR STUDY

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1 THE ARIES-I TOKAMAK REACTOR STUDY Farrokh Najmabadi, Robert W. Conn, and The ARIES Team 16th SOFT London, September 3-7, 1990

2 ARIES Is a Community-Wide Study U. W. UCLA ANL U. IL. FEDC ORNL RPI ARIES GA PPPL INEL MIT International Collaborations LANL

3 Primary Objectives ARIES Develop several design approaches for an attractive tokamak reactor with varying degrees of extrapolation in physics & technology. Determine the potential economics, safety, and environmental features of this range of possible tokamak reactors. Identify physics and technology areas with the highest leverage for achieving the safest, most environmentally attractive, and economic tokamak reactor.

4 Tokamak Vision Space

5 ARIES Reactor Designs ARIES-I is based on modest extrapolation in physics and on technology which has a 5 to 20 years development horizon (often by programs outside fusion). ARIES-II is based on aggressive extrapolation in physics (e.g., 2nd stability). ARIES-III is an advanced fuel (D- 3 He) tokamak reactor. Goal: A combination of economic competitiveness, a high level of safety assurance, and attractive environmental features.

6 ARIES-I Fusion Power Core

7 Major Parameters of ARIES-I Aspect ratio 4.5 Plasma major radius (m) 6.75 Plasma minor radius (m) 1.5 Toroidal field on axis (T) 11.3 Toroidal field on the coil (T) 21 Plasma current (MA) 10 Neutron wall loading (MW/m 2 ) 2.5 Net electric power (MWe) 1000 Net Plant Efficiency 0.39

8 Physics Features of ARIES-I 1st stability regime (C T =3.2 from MHD analysis) with selfconsistent plasma profiles for transport, current-drive, stability, and edge-plasma analysis. Steady-state operation by ICRF fast waves and self-consistent bootstrap (68%). Confinement scaling consistent with present data-base. High-recycling poloidal divertors. Low current ( 10 MA), high aspect ratio (4.5), low beta ( 2%), high field (B o 11 T, B coil 21 T).

9 Cost Comparison of Tokamak Reactors

10 Features of High-A, Low-I Operation Higher β p and bootstrap fraction; Lower current-drive power and cost; Disruption forces smaller; Lower beta; Higher toroidal field; Higher TF magnet stored energy and cost; Minimum COE in the range A 4 6; Experimental data base for A 4 6 is limited.

11 ARIES-I Major Parameters Toroidal beta (C T =3.2) 1.9% Boot-strap fraction 68% On-axis q 1.5 q ψ 4.5 κ 95 (κ x ) 1.6 (1.8) δ 95 (δ x ) 0.5 (0.7) Electron density ( m 3 ) 1.45 Electron temperature (kev) 20 Core-plasma radiation fraction 0.52 Energy confinement time (s) 2.4

12 ARIES-I Equilibrium & Stability Plasma elongation is chosen based on vertical stability requirements. κ x =1.8, κ 95 =1.6. Passive stabilization by forty 1-mm thick Al layers sandwiched between the shield panels (growth rate 200 ms). Active stabilization by a pair of coils located outside TF magnets (reactive power of 2MVA). Poloidal-field coils arranged for minimum stored energy. C T =3.2 (β =2.1%) with current density profile producible by the current drive system.

13 Folded Wave-Guide Launcher Made of SiC composite with 0.02 mm Cu coating. Power = 4 MW; E Max 36 kv/cm.

14 ARIES-I Impurity Control Estimates of high-recycling divertor parameters were made by B2 and EPIC 2-D edge-plasma codes: Peak heat flux 4.5MW/m 2 ; Peak divertor plasma temperature 25 ev. Adequate alpha ash pumping can be achieved with core τ p /τ E =4. First-wall erosion rate is estimated at mm/y.

15 Enginering Features of ARIES-I Advanced superconductor (Nb 3 Sn) toroidal-field magnets. ARIES-I blanket is a He-cooled design with SiC/SiC composite structural material, and Li 2 ZrO 3 solid tritium breeders. Composites are high strength, high temperature structural material with very low activation and very low decay afterheat. An advanced Rankine power conversion cycle as proposed for future coal-burning plants (49% gross efficiency).

16 ARIES-I Achieves Passive Safety

17 ARIES-I Components Qualify for Class-C Waste Disposal

18 ARIES-I Is Economically Reasonable

19 Physics Issues Scaling of plasma energy confinement at high aspect ratios. Burning-plasma dynamics, alpha particle transport and exhaust. Fast-wave current drive and high bootstrap current. Poloidal divertor operation at loading and plasma conditions predicted for the high-recycling mode. Disruption control.

20 Engineering Issues Manufacturing technology for large-scale SiC composite components. Effects of irradiation on the properties of SiC composites. Verification of the TF magnet design. Alternate, low-activation solid breeders (Li 2 OandLi 4 SiO 4 ). Verification of safety analysis.

21 Summary ARIES-I design is based on minimum extrapolation in physics and advanced technology with 5 to 20 years horizon. ARIES-I design is economically reasonable and has superior safety and environmental features. Improved physics performance such as in advanced tokamaks (ARIES-II) and RFPs (TITAN) result in even more desirable fusion reactors.