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Engineering models in the ARIES system code, Part II

Engineering models in the ARIES system code, Part II. M. S. Tillack, X. R. Wang, et al. ARIES Project Meeting 26-27 January 2011. Summary of status in October 2010. Line-by-line review of DesignPoint.cpp was performed

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Engineering models in the ARIES system code, Part II

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  1. Engineering models in theARIES system code, Part II M. S. Tillack, X. R. Wang, et al. ARIES Project Meeting 26-27 January 2011

  2. Summary of status in October 2010 • Line-by-line review of DesignPoint.cpp was performed • Numerous major and minor concerns were identified with power flow models in VASST • Thermal conversion efficiency • Pumping power in the blanket and divertor • Power density limits • Pump efficiencies • Fusion power partitioning to components • We decided to evaluate the potential impact of changes and concentrate on those with significant expected effect on system code output

  3. Action Items from October • System code contributions (Lane and Chuck)(end of Nov inputs, end of Dec implement) • Output formatting (Lane, Laila, Les, Chuck, …) • System code models of volumes, inclusion of He systems (Lane, Laila, Les) • New models for pumping power – He (Mark, Minami, Xueren) and PbLi (Mark, Neil, Siegfried) • Power cycle model (First quantify the impact of uncertainties)(Mark, Xueren, Lane) • Poloidal distribution (including divertor) of heat flux • CAD skeleton (Xueren) • Wall load and core radiation formulas (Laila) • Mantle and divertor radiation (Mark, Tom?, Chuck?) • Define the approach for modeling heat fluxes in the code • Provide the models • Decommissioning and waste handling costs (Laila)

  4. He pumping power in the divertor • Analysis of three options performed, with some amount of optimization vs. heat flux (more design optimization underway). • Results reduced to polynomial fits with very high R2 • No accommodation of profiles (yet) • Velocity calculated from peak location is used at all locations

  5. MHD pressure drop in the blanket • Previous studies used a fully-developed channel flow formula • Dp=0.25 MPa for ARIES-AT, dp/dx=10-3 MPa/m for ARIES-CS • However, the pressure drop from fully-developed channel flow is small compared with 3d effects • Bends • Entrance/exit to magnetic field • Flow channel insert overlaps • A standard method is to apply K factors, similar to ordinary flows • Dp3d = k N (rv2/2) • Each 3d perturbation contributes 0.1~0.5 MPa for the “standard DCLL” blanket

  6. Inboard MHD pressure drop can be a serious concern • ARIES-ST, where the DCLL was originally developed, had no inboard blanket and very low outboard B(2 T on axis, 1.25 T outboard midplane) • Pressure drop depends on B2 • Dp3d = k N (rv2/2), N = Ha2/Re = sdB2/rv • BR~constant • For the pre-strawman, Bo=6.25, Ro=5.5, a=1.375 • B2inboard/B2outboard = 2.5 • Detailed design is needed to evaluate and optimize MHD pressure drops • Limited inboard space leads to higher flow speed • Lower inboard power flows may help • Detailed design is needed to better evaluate andoptimize MHD pressure drops

  7. Total blanket pumping power • Combined He in FW (with bends), grid plates, HX and LM MHD • Tests for self-consistent temperature rise and heat transfer • Result is a simple quadratic fit for the system code • I can segregate LM and He powers if desired

  8. Thermal conversion efficiency models were not changed (DCLL) (SiC) • The entire effect is caused by degradation of bulk outlet temperature due to internal heat transfer: very design-dependent • Minor variation at lower wall loads expected for our strawmen • For DCLL, surface heat flux has minimal effect below 0.5 MW/m2 • Not clear why hth depends so strongly on q for AT blanket; probably this could be fixed

  9. Characterizing divertor and first wall heat loads with reduced models suitable for ARIES systems code - LLNL • Divertor heat loads come primarily from plasma exhaust power, Pp; heat flux Sd = Pp/4pRadDd, ad ~ ½ • Combined approaches to be used • Kukushkin/Pacher parameterization of acceptable pedestal parameters based on SOLPS modeling (published NF, JNM), to determine Dd • 2010 DOE experimental Joint Milestone gives Dd ~ 1/Ip • Two-point (midplane/divertor) models for SOL • Divertor-leg radiation from high density, lowtemperature plasma; specified by impurity content and divertor retention of impurities • First-wall heat loads primarily from radiation loss • Mantle radiation profiles can come from neutronics codes (treat edge as part of core) or UEDGE • SOL radiation to FW is expected to be small ARIES-AT 77% mantle radiation loss

  10. NEW: Pump efficiencies were reviewed and updated • PbLi MHD pump: 40% (optimistic) • PbLi mechanical pump: 80% (Morley)(S. Malang: suggests using 90%, 5% recoverable) • He compressor: 90% (5% recoverable)

  11. Partial recovery of pumping power (MHD pump example) Pump inefficiency lost (20%) System pressure drops result in LM heating (40%) LM heating within pump (40%) Wall plug power (100%) LM pump (40% efficient) blanket HX Thermal energy recovered at hth (80% x hth)

  12. Partial recovery of pumping power (mechanical pump example) Pump inefficiency lost (5%) System pressure drops result in LM heating (90%) LM heating within pump (5%) Wall plug power (100%) Mechanical pump (90% efficient) blanket HX Thermal energy recovered at hth (95% x hth)

  13. Next steps • Refinements to various blanket formulas are needed, e.g. • Inclusion of manifolding • Revisit loss factors for bends and other perturbations • Separate treatment of inboard and outboard blankets • Better estimates of peaking factors • Proper accounting of heat transfer enhancement techniques • Design details (number of channels, channel size, …) • Proceed to detailed point design studies of a SiC blanket and He-cooled W divertor for a tokamak • Need MHD formulas for SiC blanket • Treat q” and NWL in blanket separately in pumping power eqn. • Re-examine peak achievable conversion efficiency for SiC blanket • Explore blanket He pumping with a turbine

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