Progress on the Overall Power Core Configuration of the ARIES-ACT

1. Progress on the Overall Power Core Configuration of the ARIES-ACT X.R. Wang1, M. S. Tillack1, S. Malang2 1University of California, San Diego, CA 2Fusion Nuclear Technology Consulting, Germany ARIES-Pathways Project Meeting Gaithersburg, MD October 13-14, 2011

2. Review of the Design Features of the ARIES-AT Power Core • All the components including the inboard blanket and shield, outboard blanket and shield and divertor are cooled by LM LiPb. • The inboard blanket, outboard blanket, upper and lower divertor modules are integrated with the HT shield (structural ring) into one replaceable unit, and the unit is attached to the bottom structure of the VV. • All the connections/disconnections between coolant access pipes and individual component are located the outside of the outboard HT shield where the He-generation should be low enough to allow for re-welding. • All LM access pipes should be designed as concentric tubes with the cold inlet flow (~650 ᵒC) in the annulus, cooling in this way the inner tube (1100 ᵒC) to the allowable temperature (~1000 ᵒC) of the SiC/SiC.

3. Geometry Definitions of the ACT FW and Divertor Plate Are Based on the ACT-1B Strawman ARIES-ACT (Aggressive Physics) R=5.5 m A=1.375 m Elongation=2.2 Dom plate OB divertor plate IB divertor plate • Geometry Definitions of the FW and divertor plates (from Chuck): • Thickness of SOL at mid-plane=10 cm • Curved FW • OB divertor location=R-a/2 • IB divertor location=R-a Plasma IB FW Results of CAD analysis: Total plasma surface area=~475 m2 Total plasma volume=~417 m3 Total FW surface area=~452 m2 (AIB=140 m2,AOB=312 m2) Total Divertorsurface area=~143 m2 OB FW One sector (22.5 degree)

4. Two Possible Design Options for the ACT-1 Power Core Configuration

5. Power Core Configuration for the Design Option #1 (LiPb-cooled HT Shield) Thickness radius Inboard: Vacuum vessel: 0.4 m HT shield: 0.24 m IB blanket: 0.35 m Outboard: 1st Blanket: 0.30 m 2nd Blanket: 0.45 m HT shield: 0.15 m Vacuum vessel: 0.25 m Vertical build: W divertor target: ~0.07 m (He, ODS steel and W) Replaceable HT shield: 0.30 m (He, FS and ODS steel) HT shield: 0.3 m (SiC, FS and LiPb, divertor assess pipe) (0.15 m, 15% SiC, 10% LiPb, 75% FS for ARIES-AT) Vacuum vessel: 0.4 m Composition: the same as the ARIES-AT • One of the He-cooled W-based divertor concepts would be integrated into the power core.

6. Integration of the He-cooled W-based Divertor in the ACT Power Core • Fingersarranged over the entire plate • Imping-jet cooling, Tin/Texit=700/800 ᵒC • Allowable heat flux up to~14 MW/m2 • Avoiding joints between W and ODS steel at the high heat flux region • ~550,000 units for a power plant • T-Tube divertor: ~1.5 cm dia. X 10 cm long • Impinging-jet cooling, Tin/Texit=700/800 ᵒC • Allowable heat flux up to~11 MW/m2 • ~110,000 units for a power plant W-based divertor • Plate divertor: 20 cm x 100 cm • Impinging-jet cooling, Tin/Texit=700/800 ᵒC • Allowable heat flux up to~9 MW/m2 • ~750 units for a power plant W-Ta-ODS joints • Two zone divertor (any combination of the plate and finger and T-tube) • Fingers for q>~8 MW/m2,plate for q<~8 MW/m2 • Decreased number of finger units OB divertor plate • One of the divertor concepts to be integrated in the ACT power core. • The selection of the divertor depends on the peak heat flux and heat flux profile of the ACT-1. • Tubular or T-Tube He-cooled SiC/SiC divertor • Impinging-jet cooling, Tin/Texit=700/800 ᵒC • Allowable heat flux up to~5 MW/m2

7. The Modified W-Ta-ODS Joints Indicated Simpler Fabrication and Smaller Strains Ta W ODS Ta ODS W TIG or Laser Diffusion welded Explosive welded Brazed Brazed Brazed The original design The modified design • Avoided ratcheting • Reduced plastic strains in the ODS and Ta rings • Simpler design and simpler fabrication steps • Avoided singularities • Added braze layer in the joints for analysis • Assumed the material properties of the Cu to simulate the braze material, because we lacked alloy composition and properties for real brazes • ~11,000, 000 non-linear structural nodes Strain Limits: • Pure Ta, εallow=~15% at RT and 5% at 700 ᵒC • ODS-EUROFER, εallow=~2.3% and 2.4% at RT and 700 ᵒC • Pure W, εallow=~0.8% at 270 and 1.0% at 700 ᵒC • Pure Cu, εallow=~15% (unirradiated) *Dara Navaei, Master’s thesis (draft), “Elastic-plastic analysis of the transition joint for a high performance divertor target plate”

8. Coolant Routing for the Power Core Design Option #1 (LiPb-cooled HT Shield) Size of the access pipes (thermal power is based on the ARIES-AT): • Circuit 1: series flow through the inboard shield and inboard blanket region • Total thermal power=~354+110=464 MW • Total mass flow rate=~5574 kg/s, ~348 kg/s per sector (∆T=1100-650=450 ᵒC) • Diameter of the access tube=~0.22 m (assuming vPb-Li ≤ ~2 m/s) • Circuit 2: flow though the first outboard blanket region • Total thermal power=~901 MW • Total mass flow rate=~10,823 kg/s, 677 kg/s per sector • Diameter of the access tube=~0.32 m (assuming vPb-Li≤ ~2 m/s) • Circuit 3: series flow through the outboard shield and the second outboard blanket region • Total thermal power=~142+70=212 MW • Total mass flow rate=~2547 kg/s, ~159 kg/s per sector • Diameter of the access tube=~0.08 m (assuming vPb-Li ≤ ~2 m/s) • Circuit 4: Helium-cooled the upper divertor • Total thermal power=~148 MW • Total mass flow rate=~285 kg/s, ~18 kg/s per sector(∆T=800-700=100 ᵒC, P=10 MPa) • Diameter of the access tube=~0.3 m (assuming vhelium ≤100 m/s) • Circuit 5: Helium-cooled the lower divertor • Total thermal power=~148 MW • Total mass flow rate=~285 kg/s, ~18 kg/s per sector(∆T=800-700=100 ᵒC, P=10 MPa) • Diameter of the access tube=~0.3 m (assuming vhelium ≤100 m/s)

9. Replaceable Unit for the Sector Maintenance • Like the ARIES-AT power core configuration, the inboard blanket, outboard blanket, upper and lower He-cooled divertor are integrated with the HT shield into a replaceable unit for the sector maintenance. • All LM access pipes are designed as concentric tubes (the cold inlet flow (~650 °C) in the annulus, the hot outlet flow in the inner tube (1100 °C) ). • He access pipes are also designed as concentric tubes (700/800 °C for outer/inner tubes), and the advanced ODS steel is assumed for the tube material. • TAURO:LiPb: Tin=~640 ᵒC, Texit=950 ᵒC • Power conversion efficiency: ~55% with optimized compression ratio of 1.77. LiPb: Tin=~650 ᵒC, Texit=1100 ᵒC He: Tin=~700 ᵒC, Texit=800 ᵒC

10. Layout of the Coolant Circuits and the Access Pipes to the Components Flow distribution Circuit 1:series flow through the inboard shield and inboard blanket region Circuit 2: flow though the first outboard blanket region Circuit 3: series flow through the outboard shield and the second outboard blanket region Circuit 4 & 5: Helium-cooled the upper and lower divertor

11. Cutting/Re-welding of the Access Pipes for Sector Maintenance: Option #1 Bottom view showing the space of all 5 access pipes penetrating through the vacuum vessel and coil structural cap. • The locations of the PF coils have been modified based on the ARIES-AT’s PF coils in order to allow the gravity support of the power core and access pipes penetrating through the coil cap to connect the coolant ring header at the bottom. Location of cutting/re-welding

12. Cutting/Re-welding of the Access Pipes for Sector Maintenance: Option #2 • All the 5 access pipes will penetrate the vacuum port, one from upper port and 4 from the lower port. • The disconnections/connections of the access pipes are located behind the second vacuum door (the first door is the outside door). • All 5 access pipes need to be cut and removed from the port.

13. Design Options for Removable Vertical Position and Feedback Coils Vertical Position Coils (normal conducting coils) Alternative design option: The vertical position coils and feedback coils would be vertically removed up and down to the grooves of the VV. The ARIES-AT like design option: The vertical position coils and feedback coils would be attached to the vacuum door, and need to break the joints and removed horizontally. • Both options work well with the configuration of the access pipes penetrating through the VV door and port.

14. Power Core Configuration for the Design Option #2 (He-cooled HT Shield) He-cooled He-cooled • 1st design option: • LiPb flow through upper/lower divertor regions or just flow through the lower divertor region • One LiPb circuit cooling both inboard and outboard blankets with 2 access pipe bundles (1/2 blanket sector per bundle) and 2 Helium circuits • Need thickness imputs for both inboard and outboard HT shield • May also need a new radial build • Alternative design option: ARIES-AT like configuration • 3 LiPb circuits • 2 Helium circuits

15. Coolant Routing for the Power Core Design Option #2 (Helium-cooled Shield) • Circuit 1:LiPb flow through both the inboard blanket and 2 outboard blanket regions • Total thermal power=~354+901+142=1397 MW • Mass flow rate/sector= ~1048 kg/s (∆T=1100-650=450 ᵒC) • 2 access pipe bundles including all the 24 blanket channels (0.6 x 0.6 for each bundle) • Circuit 2:Helium series flow through outboard HT shield and the upper divertor • Total thermal power=~148+110=258 MW • Mass flow rate/sector=~31 kg/s(∆T=800-700=100 ᵒC, P=10 MPa) • Diameter of the access tube=~0.4 m (assuming vhelium ≤~100 m/s) • Circuit 3:Helium series flow through inboard shield and the lower divertor • Total thermal power=~148+70=218 MW • Mass flow rate/sector=~26.2 kg/s(∆T=800-700=100 ᵒC, P=10 MPa) • Diameter of the access tube=~0.36 m (assuming vhelium ≤~100 m/s)

16. Access Pipe Bundle Applied in Overall Layout for Minimizing 3D MHD ∆P Multiple small ducts (Access pipe bundle, proposed by Mark) Constant flow cross section • Two access pipe bundles are arranged to connect all the 36 inboard and outboard blanket channels (12 for the inboard and 24 for the outboard blanket). • He-cooled HT shield may be a better design option to simplify the LiPb coolant circuits and reduce the 3D MHD uncertainty.

17. Layout of the LiPb Coolant Circuit and the Access Pipes for the Design Option #2 Cross-section of the outboard blanket channels for one half sector 1st OB blanket IB blanket Constant flow cross-section 2nd OB blanket Connecting to 36 blanket channels channel by channel Connecting to the LiPb Ring Header ARIES-AT like design 1stLiPb circuit

18. Discussion • Need to make selections: • Integration of the He-cooled divertor concepts (a few design options) • Finger • T-Tube • Plate • SiC/SiC with W coating tubular or T-tube concept • Two zone divertor (any combinations) • Inboard and outboard shield (2 options) • LiPb-cooled • Helium-cooled • The location of the disconnections/connections of all the access pipes (2 options) • Behind the outboard shield, penetrating through the bottom coil cap • Behind the second vacuum door (inner), penetrating through the vacuum port • The way to remove the vertical position and feedback coils (2 options) • Horizontal movement (ARIES-AT like design option): need to break the joints of the coils and remove the coils with the second vacuum door together • Vertical movement: need to pull two coils up and two coils down to the grooves of the top and bottom VV parts.