CFD Analysis for ITER FW/Shield Designs

1. CFD Analysis for ITER FW/Shield Designs Alice Ying, Ryan Hunt, Hongjie Zhang (UCLA) Dennis Youchison James Bullock, Mike Ulrickson (SNL) July 8, 2009 MIT, Boston

2. First wall / shield -- Geometric Complexity BLKT_04_FW_2009_DESIGN #2PTYX7 Count the pieces: 560 Be tiles/40 pieces of CuCrZr heat sinks/20 pieces of SS bodies/80 SS tubes inside Cu heat sinks/52 plugs 40 welding pieces/Manifold, connectors, etc.

3. Velocity plot in water volume for FW Panel for BM_04 • Design Issues: • Flow non-uniformity and manifold design • Hot spots and accommodation of local high heat flux • Pressure drop optimization • Structure thermomechanical optimization • CFD Challenges • Large problem sizes • Multiple materials • Geometric complexity • Temperature depended properties • Incorporation of complex thermal loading conditions for other codes Total: 8 kg/s mass flow rate 20 circuits each half module 0.2 kg/s per finger 80 circuits fed from a single inlet pipe

4. Contact!! It may be interesting to do CFD in one finger. Preparation of CFD meshes and removal of all interferences and errors - (there are many details- Impact on fabrication/cost )

5. at turn-around at outlet In some cases, analysis can be done for a smaller compartment (here a SS panel of the FW) to reveal local design feature. Flow around the turn around and near the outlet collector show interesting recirculation flow. Inlet mass flow rate: 0.4 kg/s CFD Analysis for SS Panel 1 (BLKT_04_FW_2009_DESIGN #2PTYX7) Each SS panel houses 2 fingers

6. Uniformity of pipe velocity? m/s 1.356 1.774 Velocity magnitudes at different pipe mid-planes show slightly higher values for the top two pipes

7. Hypervaportron heat transfer validation Heat spread to the neighboring Cu results in a 30C lower than what reported last week • P. Chen, et. al. Correlation for Hypervaportron (2008) • Shah correlation for flat surface (1977) Adiabatic BC applied to surfaces: no heat communication with neighboring tilesexcept through Be/Cu contact 400 g/s Hypervaportron Finger Next: 5 MW/m2 applied to both half of the 2nd and 3rd tiles 3rd Be tile (5 cm wide) exposed to 5 MW/m2 1st, 2nd and 4th Be tiles exposed to 0.2 MW/m2 Be surface temperatures under 5 MW/m2

8. Velocity characteristics under the grooves – data used for groove optimization 3 grooves Max Cu surface Temp = 308 C 2 grooves Max Cu surface Temp = 310 C

9. FW temperature response to single strip high heat flux of 5 MW/m2 (At toroidal location 0.282<y<0.332) The rest of the surface is exposed to 0.2 MW/m2 • Maximum Be surface temperature ~778oC • Previously, a single fingerexposed to similar conditions, the maximum surface temperature was reported at 769oC Mass flow rate: 8 kg/s total or 200 g/s per finger simplified model (without manifold)

10. at Y=0.35 Some fluid velocity details show flow non-uniformity

11. CFD/thermal analysis for the BM04 shield block at different radial planes (color quantities: velocity m/s inside the pipe; temperature oC: SS) • Russian Design • -4 series circuits • radial flow paths • large water volume fraction, • relatively cold compared with other designs. IO is still yet to decide which design option should be considered

12. 2 inlets each with 4 kg/s Water enters the shield through the central pipe and distributes into 2 passes poloidally at the end of the pipe (x ~0.64 m) Water leaves the shield through 4 outlet holes in this model CFD analysis helps to see how water flows within the module

13. Alternate shield design utilizing poloidal flow paths. CFD analysis reveals design needs much improvement to fix the flow non-uniformity and consequent hot spots. the IO CAD transmitted to the US has a hole – water leaks out. Hole found in slot BLANKET_2009_DESIGN#2PTXPT

14. Previous model Cover plates modified The model includes a coaxial connector Modified BM04 model CFD analysis for the modified BM04-shield Goal: to evaluate whether the back of the shield will be too hot under long pulse (3000 s) runs (using steady state run for initial check) Modified model

15. CFD Analysis for BM04 Model BLKT_04_BSM_2009_DESIGN#2PCQZA-C-052609 (US fixed) Water volume = 0.0284942 m3 Steel volume= 0.254979 m3 Steady State Analysis CFD model total nuclear heat to BM04 = 0.40473 MW Water= 0.0494 MW Steel = 0.35531MW (MCNP calculated total nuclear heat = 0.395 MW with steel = 0.348 MW ) CFD water outlet temperature= 112.01C (Inlet T= 100 C; inlet mass flow rate = 8 kg/s) Fractional heat balance (Qinput/Qoutout) = 1.0006 DP = 148864 Pa

16. Plan X = 3.78 Temperature gradient plot shows heat flow directions and the relative location with respect to the coolant pipes • Maximum temperature at the back ~ 250 C • Shield maximum temperature = 266.1C

17. Plan X=3.78 Inlet Velocity Distribution for BLKT_04_BSM Again, use of parallel flow paths in the design results in some flow non-uniformity Some flow non-uniformity corresponding to ~ 30oC temperature non-uniformity

18. The Next Step: Pulsed Operation Analysis, Initial result: Steel Surface Temperature at the Plasma Shutdown after Ramp-down Peak temperature drops ~19 degree lower than the steady state peak, but its location shifts to the back Starting with steady state temperature conditions (time =0). Power is completely off at 60 s No flow transient is observed, water velocity distribution remains the same during power ramp and down

19. Main areas of future work for FW / Blanket / Divertor • He cooled first wall and divertor simulations for TBMs and Demo Divertors • Coupled HIMAG / CFD / Neutronics / Structural codes for virtual blanket