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LOCA/LOFA Analyses for LiPb/FS System

LOCA/LOFA Analyses for LiPb/FS System. Carl Martin, Jake Blanchard Fusion Technology Institute University of Wisconsin - Madison ARIES-CS Project Meeting November 4-5, 2004. LOCA/LOFA Analysis Update.

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LOCA/LOFA Analyses for LiPb/FS System

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  1. LOCA/LOFA Analyses for LiPb/FS System • Carl Martin, Jake Blanchard • Fusion Technology Institute • University of Wisconsin - Madison • ARIES-CS Project Meeting • November 4-5, 2004

  2. LOCA/LOFA Analysis Update • Description of the thermal models, boundary conditions, and assumptions used for the LOCA/LOFA analyses. • Update of results presented previously to include plasma / nuclear heating for 3 seconds after loss of coolant. • LOCA/LOFA analysis with new Li/Pb afterheat data. • Modeling in progress to include support structure.

  3. 1 Thickness (cm) 9 31 ≥ 2 18 28 2.2 47 31 2 4.8 SOL Blanket (LiPb/FS/He) Plasma FW Vacuum Vessel Winding Pack FS Shield External Structure Gap + Th. Insulator Back Wall Coil Case & Insulator Gap Gap | | ≥ 149 cm LiPb/FS/He Radial Build(Water Cooled Internal VV) • These LOCA/LOFA analyses assume perfect insulation between the vacuum vessel ant the coil case, i.e. no heat loss. • Also, no support structure in gaps included.

  4. LiPb Ferritic Steel Boronated Ferritic Steel ANSYS FE Model and Boundary Conditions for Thermal Analyses • Adiabatic boundary at back of vacuum vessel • Model is axisymmetric about plasma centerline and symmetric on sides • Emissivity of 0.3 assumed across vacuum gaps and vacated cooling channels • All analyses assume there is no helium in channels Blanket Shield Vacuum Vessel Radius = 2.0 m Gap Gap H20 H20 H20 First Wall Tinit = 500 C LiPB Tinit = 625 C Back Wall Tinit = 450 C Shield Tinit = 450 C Vacuum Vessel Tinit = 100 C

  5. Blanket Shield Vacuum Vessel SiC liner Radius = 2.0 m Gap Gap First Wall Tinit = 500 C Back Wall Tinit = 450 C Shield Tinit = 450 C Vacuum Vessel Tinit = 100 C Analyses without LiPb in Blanket Including Surface and Nuclear Heating • Surface and nuclear heating continues for three seconds after loss of coolant • First case assumes loss of all coolants – complete LOCA

  6. Complete LOCA Thermal Response • Without coolant or heat loss, temperature continues to rise. • Surface and nuclear heating have little long term effect. Long term temperature rise increases by 0.2 C. First peak temperature increases by 2.6 C. Long Term Response (10 Days) Short Term Effect of Surface Heating (600 sec.) Temperature spikes 100 C at 1st wall due to surface heating at 3 sec. First peak (3.6 hr)

  7. LOCA in Blanket and ShieldLOFA in Vacuum Vessel • Natural convection to water in vacuum vessel assumed • Heat transfer coefficient of 500 W/m2-C to 100 C water • Surface and nuclear heating continues for three seconds Blanket Shield Vacuum Vessel SiC liner Radius = 2.0 m Gap Gap water water water First Wall Tinit = 500 C Back Wall Tinit = 450 C Shield Tinit = 450 C Vacuum Vessel Tinit = 100 C

  8. Thermal Response for LOCA in Blanket/Shield and LOFA in Vacuum Vessel • Peak temperature of 730 C occurs 3.6 hr after loss off coolant / flow and continues to drop with time. • Addition of surface and nuclear heating increases peak by 2.5 C. • Results not particularly sensitive to VV convection assumptions.

  9. LiPb Ferritic Steel Boronated Ferritic Steel Analyses Including the Static Presence of LiPb in the Blanket • Updated estimates of LiPb afterheat included. Heating levels much lower than previously assumed. • Nuclear heating assumed for three seconds after loss of flow. • Analysis repeating with (LOFA) and without water (LOCA) in vacuum vessel. Blanket Shield Vacuum Vessel Radius = 2.0 m Gap Gap H20 H20 H20 First Wall Tinit = 500 C LiPB Tinit = 625 C Back Wall Tinit = 450 C Shield Tinit = 450 C Vacuum Vessel Tinit = 100 C

  10. Afterheat in Blanket Materials • LiPb afterheat scaled from ARIES-AT data. • Previously presented results (Sept.) had used heating for steel.

  11. Thermal Results LOFA for LiPb and LOCA for He and Water • Resulting temperatures slightly lower than complete LOCA.

  12. Thermal Results LOFA for LiPb and Water and LOCA for He • Maximum temperature 17.8 C less than the case without LiPb.

  13. Support Structure Modeling • Model to include heat loss through supporting leg and also structures in vacuum gaps. • Potential to model noncircular cross-sections. • Heat transfer from vacuum vessel to coils may also be included. Vacuum Vessel Shield Blanket Supporting Leg

  14. Summary • Peak temperatures are below 730 C for cases with LOFA in the vacuum vessel. Results not particularly sensitive to VV convection assumptions. • Without heat removal (LOCA in VV), the temperatures continue to rise over time. • The addition of surface and nuclear heating for three seconds after LOCA increased the peak temperature by 2.5 C. • Models are being developed to include support structure and heat loss from vacuum vessel.

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