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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

## 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. Temperature profile (with heat release)

15. TRANSIENT ANALYSISSet of Off-normal Conditions

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