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Thermal-Hydraulic Analysis in Normal and Off-normal Conditions

Thermal-Hydraulic Analysis in Normal and Off-normal Conditions. Ing. F. Bianchi, Dr. V. Moreau, Dott. C.Petrovich Presented by Dr. Davide Giusti. WP 4.3 meeting Stockholm, April the 7 th 2003. OUTLINE. STEADY STATE ANALYSIS Design goals and limits Numerical model

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Thermal-Hydraulic Analysis in Normal and Off-normal Conditions

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  1. Thermal-Hydraulic Analysis in Normal and Off-normal Conditions Ing. F. Bianchi, Dr. V. Moreau, Dott. C.Petrovich Presentedby Dr. Davide Giusti WP 4.3 meeting Stockholm, April the 7th 2003

  2. OUTLINE • STEADY STATE ANALYSIS Design goals and limits Numerical model Proton beam heat deposition Preliminary results • TRANSIENT ANALYSIS Set off- normal conditions

  3. DESIGN LIMITS AND GOALS • LBE fluid flow speed  2m/s close to walls • Average flow speed: 0.5  0.6 m/s • Temperature free surface: < 450°C • Temperature target materials: < 450° C • Nearly all (95%) heat release inside the LBE loop • Flow distribution: horizontal uniform, higher on top and without recirculation to counter heat release distribution such as to respect constraints.

  4. Numerical model • Tools: StarCD code • Simulation of 1/2 domain due to symmetry of geometry • 330.000 cells • Horizontal plates simulated by a localized variable momentum source (Su, Sv, Sw): Su= -Cu*r*Vmag*u/2dx Sv= -Cv*r*Vmag*v/2dx Sw= -Cw*r*Vmag*w/2dz 0< Cv=Cu < 6 dx=2 cm dz=5 mm

  5. Proton beam heat deposition • Methodology: • Hypothesis: distributed heat deposition • Energy deposition line approximated by normalized sum of 161 cylindrical beams positioned each 0.5 mm over a 8 cm line • Advantage: Modify the beam path without need of additional neutronic calculations Same accuracy as for the single beam (same accuracy with neutronic code need to use a “statistic” 181 times heavier)

  6. Proton beam heat depositionSingle beam • Tools: Montecarlo computer code MCNPX 2.5 b CEM2K (Cascade Exciton Model) E >150 MeV Cross section libraries LA 150 n and LA 150 h E <150MeV • Density current profile described with x-y gaussian (x=y=0.153 cm) • Beam footprint: 1 cm • Proton current: 1 mA • Core + target modelled in 3-D geometry heterogeneous way • Core Keff = 0.97 and two different enrichment • Contribution of fission neutrons: neglected against energy deposited by proton beam • Simulation domain: cylinder 32 cm high, 5 cm radius

  7. Proton beam heat deposition Energy deposition has been generated with a dedicated fortran program, according to the following scheme: • Read the neutronic data on a grid in cylindrical coordinates (single calculations) • Transpose the neutronic data on a much finer local Cartesian grid (small error). • Apply 161 times the local Cartesian grid to a global fine Cartesian grid (no error). • Make a coarser grid, congruent with the CFD grid from local integration of the fine Cartesian grid (no error).

  8. Proton beam heat depositionSingle beam • Total power deposited: 389 kW/mA (less than 72% of total power)  10% missing • Bragg peak about 29.3 cm from free surface for T = 412°C • Bragg peak displacement due to density(T) downbeam distribution: has been neglected • Missing power is caused by a too small simulation domain

  9. Preliminary resultsBeam intensity = 6mA • Total heat release 2.294 MW • Mass flow rate 206 kg/s • Volume flow rate 20 l/s • Heat release box (cm) 10*12*32 • Inlet temperature (uniform) 310 C • Maximum surface temperature increase 100.6 K • Maximum bulk temperature increase 134.5 K • Maximum wall temperature increase (propeller axis) 132.3 K • Maximum wall temperature (external vertical wall) 100.0K • Maximum outlet temperature increase 121.0 K • Minimum outlet temperature increase 31.9 K • Mean pressure drop between inlet and outlet 6200 Pa • Pressure variation in outlet 780 Pa • Pressure variation on the would-be free-surface (6 cm wide) 300 Pa • Inlet velocity (uniform) 0.67 m/s • Vertical velocity variation in outlet (m/s) <-1.02,-0.3>

  10. Heat deposition from proton beam (W/cm3)

  11. Speed (m/s) Temperature (K)

  12. Temperature profiles on the walls viewed from the external on the left and from XZ – plane on the right

  13. Sensitivity analysis • Finalized to demonstrate the need of flow shaping (flow diverter: grid, plate) • Only 2D simulation with a similar geometry • Vertical flow diverter at the beginning of the flow inversion (plate)

  14. Effect of flow diverter on the velocity profile (no heat release)

  15. Effect of flow diverter on the velocity profile (with heat release)

  16. Temperature profile (with heat release)

  17. TRANSIENT ANALYSISSet of Off-normal Conditions

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