1. Mass transfer modeling for LM blankets Presented by Sergey Smolentsev (UCLA) with contribution from: B. Pint (ORNL) R. Munipalli, M. Pattison, P. Huang (HyPerComp) M. Abdou, S. Saedi, H. Zhang A. Ying, N. Morley, K. Messadek (UCLA) S. Malang (Consultant, Germany) R. Moreau (SIMAP, France) A. Shishko (Institute of Physics, Latvia) Fusion Nuclear Science and Technology Annual Meeting August 2-4, 2010 UCLA

2. In this presentation: Status of R&D on development of MHD/Heat & Mass Transfer models and computational tools for liquid metal blanket applications Examples: corrosion & T transport OTHER RELATED PRESENTATIONS at THIS MEETING TITLEPresenterOral/Poster Tritium Transport Simulations in LM Blankets H. Zhang UCLA oral Modeling Liquid Metal Corrosion S. Saedi UCLA poster Integrated Modeling of Mass Transport Phenomena in Fusion Relevant Flows R. Munipalli HyPerComp poster

3. Mass transfer in the LM flows is one of the key phenomena affecting blanket performance and safety Traditionally, major considerations associated with the LM flows are the MHD effects. But there are more…. Tritium permeation is an issue – no solution has ever been proven Corrosion/deposition severely limits the interfacial temperature and thus represents an obstacle to developing attractive blankets at high temperature operation Blanket: “Hot” leg. Mass transfer coupled with MHD. Corrosion. T production. T leakage into cooling He. Formation of He bubbles in PbLi and trapping T. Ancillary system: “Cold” leg. Turbulent flows. Wall deposition and bulk precipitation. T leakage into environment. T extraction. Cleaning up.

4. Main objectives of mass transfer modeling Blanket: Revisit maximum PbLi/Fe t (470  ?) and wall thinning (20  m/year ?) Estimate T leakage into cooling He streams in the blanket Ancillary system: Estimate T leakage into environment Model T extraction processes Model clogging/deposition Model clean up processes Phenomena, design: Address “new” phenomena (i.e. He bubble formation in PbLi and trapping T by the bubbles) Find new design solutions/modifications Challenge! The whole PbLi loop, including the blanket itself and the ancillary equipment, must be modeled as one integrated system

5. What do we need? New phenomenological models for: - interfacial phenomena - nucleation/crystallization - particle-particle/wall interaction - MHD effects on mass transfer - T transport physics New material databases (He-T-PbLi) New mass transfer solvers and their coupling with existing MHD/Heat Transfer codes He bubble transport and trapping T by the bubbles is not well understood

6. What tools do we use? HIMAG as a basic MHD/Heat Transfer solver Many UCLA research MHD, Heat & Mass transfer codes CATRIS (in progress) as a basic mass transfer solver Many thermohydraulic / mass transport codes The R&D on the development of new phenomenological models and their integration into numerical codes is underway

7. CATRIS: MATHEMATICAL MODELS 1.Dilution approximation, C i <C i0 2.Lagrangian particle tracking, C i >C i0 3.Multi-fluid model, C i >>C i0

8. MODELING EXAMPLES ExampleDescriptionModeling status #1 Riga experiment Modeling of “corrosion” experiment in Riga, Latvia on corrosion of EUROFER samples in the flowing PbLi at 550  in a strong magnetic field Good match with experimental data on mass loss. Addressing groove patterns needs more sophisticated modeling. #2 Tritium transport Numerical analysis of tritium transport in the poloidal flows of the DCLL blanket with SiC FCI under DEMO blanket conditions Analysis for the front duct of the DCLL DEMO OB blanket has been done using a fully developed flow model. #3 Magnetic trap Modeling of extraction of ferrous material suspended in the flowing liquid in a magnetic trap First “demo” results have been obtained using Lagrangian particle tracking model under some assumptions for B~ 0.1 T. #4 Sannier equation Modeling of corrosion of ferritic/martensitic steels in turbulent PbLi flows to reproduce existing experimental data and to address the effect of a magnetic field In progress. Computations are performed using the UCLA corrosion code (Smolentsev). Turbulence in a magnetic field is modeled via “k-eps” model.

9. Riga experiment 1/11: setup Simulation of “CORROSION” EXPERIMENT in Riga PbLi loop EUROFER samples B=0, B=1.7 T T=550  C U=2.5 cm/s, U=5 cm/s Time=2000 hours Rectangular duct, 2.7x1 cm 2 Two 12-cm sections of 10 samples in a row, one section at B=0 and one at B=1.7 T Courtesy of Dr. Andrej Shishko, Institute of Physics, Latvia

10. Riga experiment 2/11: results Macrostructure of the washed samples on the Hartmann wall in 3000 hrs at 550  B=0B=1.7 T U o =2.5 cm/sU o =5 cm/s #B=0,TB=1.7,TB=0,TB=1.7,T 1376593437743 2245564338757 3303481330623 4193486283605 5223456251506 6257440-- 7163483248482 8198484310512 9214566321463 10205502314474 Mass loss, mg Mass loss is almost doubled in the presence of B-field PbLi flow Courtesy of Dr. Andrej Shishko, Institute of Physics, Latvia

11. Riga experiment 3/11: results In addition to wall thinning, periodic grooves aligned with the flow direction have been observed on the Hartmann wall Mechanism of groove formation is still not well understood A. Shishko (Latvia): higher velocity in the surface cavities causes higher corrosion rate. The effect may be related to specimen machining R. Moreau (France): the grooves are due to instability mechanism associated with induced electric currents crossing the interface Courtesy of Prof. Rene Moreau (SIMAP, France) Wall thinning: 1.5->1.4 mm Grooves: 40  m deep ~ 500  m ~40  m FLOW Magnetic field

12. Riga experiment 4/11: mathematical model Basic assumptions Fully developed, laminar flow Only Fe is considered Purely dissolution mechanism No oxygen passivation layer Mass transfer controlled corrosion Zero Fe concentration at x=0 Two BC types have been tested (C 0 is the saturation concentration at given t)

13. Riga experiment 5/11: material properties* Diffusion coefficient Fe-PbLi: 6.4E-09 m 2 /s** Saturation conc. C 0 : 6.26 g/m 3 *** PbLi viscosity: 1.08E-07 m 2 /s PbLi density: 9300 kg/m 3 PbLi electrical conductivity: 0.7E+06 S/m Ha=0 and 227.3 (1.7 T); C w =0.78; Re=1157 and 2314 * At 550  C ** Based on equation of Sutherland-Einstein ***Recommended by Riga people (=0.676 wppm). C o : more than THREE order of magnitude difference ??? Solubility of Fe in PbLi

14. Riga experiment 6/11: modeling results B=1.7 T, Cw=0.78, U=2.5 cm/s B=0, U=2.5 cm/s

15. Riga experiment 7/11: modeling results Riga group: C 0 =6.26 g/m 3, K=4.27E-05 m/s Grjaznov et al: C 0 =3.25 g/m 3 MASS LOSS: comparison with the experiment 430 215 Mass loss,  m/year Konys: 700  m/year 500  C, 0.22 m/s, 0T

16. Riga experiment 8/11: modeling results Riga group: C 0 =6.26 g/m 3, K=4.27E-05 m/s Effect of the velocity and B-field on the wall and bulk concentration

17. Riga experiment 9/11: modeling results Effect of the velocity - no magnetic field - Hartmann wall Wall effect - with magnetic field Effect of B-field -Hartmann wall

18. Riga experiment 10/11: modeling results Wall concentration Bulk concentration Riga group: C 0 =6.26 g/m 3, K=4.27E-05 m/s Development length > 10 m (B=1.7 T, U=5 cm/s)

19. Riga experiment 11/11: conclusions Riga experiment on EUROFER-PbLi corrosion has been successfully modeled (not including grooves) Higher corrosion rate of EUROFER samples in a presence of a magnetic field can be explained by the steep velocity gradient in the Hartmann layer Boundary condition at the solid-liquid interface is still an open issue. Saturation concentration at the wall can be used as a first approximation Uncertainty in experimental data on transport properties (e.g. saturation concentration) severely limits modeling predictions If to extrapolate to LM blanket conditions - the mass transfer development length can be more than 10 m

20. Tritium transport, 1/6 DCLL DEMO blanket conditions (outboard) Poloidal flow in a front duct with a 5-mm SiC/SiC FCI HIMAG is used to simulate MHD flow, assuming fully developed flow conditions CATRIS is used to simulate tritium transport in the multi-material domain, including PbLi flow, SiC FCI and Fe wall Goals: (1) T permeation into He; (2) sensitivity study Neutron wall loading (peak): 3.08 MW/m 2 Surface heating: 0.55 MW/m 2 PbLi Tin/Tout: 500/700  C Flow velocity: 6.5 cm/s Magnetic field: 4 T Inlet T concentration: 0 T generation profile: 4.9E-09 Exp(-3y), kg/m 3 -s

21. Tritium transport, 2/6 Pb17LiRAFSSiC FCI Solubility mol/m 3 /Pa 0.5 [1,2,3] D m 2 /s Solubility mol/m 3 /Pa 0.5 [4] D m 2 /s Solubility mol/m 3 /Pa 0.5 D m 2 /s [5,6] σ S/m Low High 0.0005 0.1 1.0 ×10 -9 7.0 ×10 -9 0.00251.5×10 -8 0.1175.0×10 -16 5 500 Physical properties 1.Mas de les Valls, E., Sedano, L.A., Batet, L., Ricapito, I., Aiello, A., Gastaldi, O., Gabriel, F. (2008) Lead-lithium eutectic material database for nuclear fusion technology. J. Nuc. Mat. 376, 353-357. 2.Reiter, F. (1991) Solubility and diffusivity of hydrogen isotopes in liquid Pb-Li. Fusion Eng. and Design. 14, 207-211. 3.Aiello, A., Ciampichetti, A., Benamati, G. (2006) Determination of hydrogen solubility in lead lithium using sole device. Fusion Eng. and Design. 81, 639-644. 4.Aiello, A., Ciampichetti, A., Benamati, G. (2003) Hydrogen permeability and embrittlement in Eurofer 97 martensitic steel. ENEA Report SM-A-R-001. 5.Causey, R.A., Wampler, W.R. (1995) The use of silicon carbide as a tritium permeation barrier. J. Nuc. Mat. 220-222, 823-826. 6.Causey, R.A., Karnesky, R.A., San Marchi, C. (2009) Tritium barriers and tritium diffusion in fusion reactors. http://arc.nucapt.northwestern.edu/refbase/files/Causey-2009_10704.pdf http://arc.nucapt.northwestern.edu/refbase/files/Causey-2009_10704.pdf There is a considerable degree of uncertainty in the physical properties, particularly for the solubility of T. That is why sensitivity study is needed.

22. Tritium transport, 3/6 Side-wall jets in the bulk Side-wall gap flow s Hartmann-wall gap flows The electrical conductivity of FCI may have a strong effect on the T transport via changes in the velocity, especially in the 2-mm gap  =100 S/m, Ha=15,900

23. Tritium transport, 4/6 T concentration (10 -6 kg/m 3 ) for cases with low (0.001 mol/m 3 /Pa 0.5 ) and high (0.05 mol/m 3 /Pa 0.5 ) solubility of T in PbLi X=0.5 m X=1.5 m Low solubility High solubility X=0.5 m X=1.5 m Magnetic field

24. Tritium transport, 5/6 Fluxes of tritium through the steel. S= 0.001 mol/m 3 /Pa 0.5, units are 10 -9 kg/m 2 /s More T permeation occurs from the Hartmann gap, where velocity is low #DSσT leak 10 -9 m 2 s -1 mol m -3 Pa - 1/2 Ω -1 m -1 % 110.0151.30 22.540.0151.40 370.0151.35 42.540.000552.08 52.540.00151.99 62.540.00551.65 72.540.0550.60 82.540.150.35 92.540.01500.36 102.540.015000.06 Total tritium loss in the front duct Total T leakage < 2%

25. Tritium transport, 6/6 Due to very low diffusion coefficient of T in SiC, FCI can be considered as a T permeation barrier All tritium generated in the bulk flow remains there. Tritium permeation occurs mostly from the gaps, especially from the Hartmann gap, where velocity is very low Electrical conductivity of the FCI has indirect effect on T transport via changes in the velocity profile: higher  - smaller leakage Total T leakage into He can be estimated as 2% of all tritium generated in the blanket (not taking into account pressure equalization openings and 3D flow effects) More accurate databases for physical properties are needed