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GRAN SASSO’S HADRON STOP Temperature’s behaviour under specified beam conditions Barbara Calcagno

GRAN SASSO’S HADRON STOP Temperature’s behaviour under specified beam conditions Barbara Calcagno. CNGS Facilities. Beam Conditions. 2D Energy deposition map [FLUKA]. FORTRAN interpolation program to convert the energy deposition map: 2D  3D. Integration of the data over the whole volume.

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GRAN SASSO’S HADRON STOP Temperature’s behaviour under specified beam conditions Barbara Calcagno

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  1. GRAN SASSO’S HADRON STOP Temperature’s behaviour under specified beam conditions Barbara Calcagno

  2. CNGS Facilities

  3. Beam Conditions 2D Energy deposition map [FLUKA] FORTRAN interpolation program to convert the energy deposition map: 2D  3D Integration of the data over the whole volume • ET-2D = Total energy - 2D model=17 kW • ET-3D = Total energy - 3D model = 16.9 kW • Difference < 0.6% negligible for the purpose of the calculations performed

  4. PURPOSES OF THE BEAM DUMP • Contain in a relatively small volume the radioactivity introduced by the beam particles reaching the end of the decay tunnel • Shield the detectors from the beam particles reaching the end of the decay tunnel • Contain the energy deposited by the beam particles and keep the local temperature within acceptable limits, during the longest data taking period (200 days) at the highest possible beam intensity (13.8x1019 pot/year) and at a proton beam energy of 400 GeV • Contribute to the shield of a possible near detector against muons produced by pions decayingin the decay tunnel

  5. PRELIMINARY CONSIDERATIONS • The mass of graphite and cast iron are made of blocks: the maximum roughness measured and, consequently, the maximum air gap between graphite and cast iron blocks is of 2 mm and 4 mm respectively. The contact between blocks, even if not perfect, is at least guaranteed over 50% of each surface. It has been decided to simplify the model making the pessimistic hypothesis that between blocks there is no contact but a layer of air, considered a solid with low conductivity, neglecting the effects of radiation and convection. • Preliminary calculations without cooling system shown that the temperature reach a value of 700 oC  needing of a cooling system

  6. COOLING SYSTEM Preliminary calculations without cooling system: 700 0C after 200 days  Destruction of concrete structures  Needing of a cooling system HYPOTHESES - Cooling power 50 kW - diameter of the tubes = 4 cm - number of tubes = 12 - Turbolent regime U = 0.2 m/s - Tbulk =17 0C  - Flow rate for each tube = 6.5 l/min -Nu=0.012 (Re0.87-280) Pr0.4 1.5 Pr 500 3x103 Re 106  - h  500 W/m2K 

  7. CALCULATIONS HYPOTHESES COMMON ASSUMPTIONS  STANDARD CASE: Graphite blocks - horizontal and longitudinal airgap = 2 mm Kxx = 7.9 W/mK Kzz =9.4 W/mK - vertical airgap = 0.5 mm Kyy = 26.4 W/mK Iron blocks - horizontal and longitudinal airgap = 4 mm Kxx = 6.0 W/mK Kzz =9.8 W/mK - vertical airgap = 2 mm Kyy = 10.9 W/mK INITIAL TEMPERATURE = 20 0C  EXTERNAL SURFACES OF THE MODEL INSULATED (worst case) NO CONVECTION IN THE MUON PIT: the air is considered as “one block material” A-GEOMETRYB-GEOMETRY VERTICAL SIMMETRY  NO FLUX THROUGH THE SURFACES OF SIMMETRY  Only a quarter of the dump is modeled  1 COOLING SYSTEM located immediately below the aluminum box, with the same cooling power of 50 kW. VERTICAL SIMMETRY - HORIZONTAL SIMMETRY  NO FLUX THROUGH THE SURFACES OF SIMMETRY  Only a quarter of the dump is modeled  2 COOLING SYSTEMS located immediately below and above the aluminum box, with the same cooling power of 50 kW.

  8. A-GEOMETRY of the HADRON STOP GRAPHITE ALLUMINUM TRANSVERSAL SECTION HEAT SINK 2.6 m 2.8 m 4.0 m 6.0 m CAST IRON AIR 0.2 m CONCRETE LONGITUDINAL SECTION 3.0 m 5.0 m 18.2 m 5.0 m 23.8 m

  9. B-GEOMETRY of the HADRON STOP TRANSVERSAL SECTION GRAPHITE ALLUMINUM 1.3 m 1.4 m 1.6 m 2.0 m HEAT SINK CAST IRON AIR CONCRETE LONGITUDINAL SECTION 3.0 m 3.2 m 5.0 m 18.2 m 5.0 m

  10. A-Geometry.Temperature profile on the transversal section related to the maximum temperature reached in graphite after 200 days - 4.5x1019 pot/year 6 HOURS 12 HOURS 24 HOURS 5 DAYS 10 DAYS TEMPERATURE[0C] 25 DAYS 50 DAYS 100 DAYS 200 DAYS

  11. A-Geometry.Temperature profile on the transversal section related to the maximum temperature reached in graphite after 200 days - 4.5x1019 pot/year TEMPERATURE[0C] 24 HOURS 5 DAYS 10 DAYS 50 DAYS 100 DAYS 200 DAYS

  12. A- Geometry: load cases studied The results of the “worst case” considered - 13.8x1019 pot/year-without concrete - show the needing of studying the possibility of using a second cooling system.

  13. B-Geometry.Temperature profile on the transversal section related to the maximum temperature reached in the graphite after 200 days - 13.8x1019 pot/year 6 H 12 H 24 H 3 Days 5 Days In 5 days the transient could be considered concluded: the maximum temperature in graphite (194 0C) is reached TEMPERATURE[0C] Starting from the 10th day, the temperature profile doesn’t change with the time 10 Days 20 Days 200 Days

  14. Temperature Profile after 200 days of running and comparison between the maximum temperatures obtained with 1 and 2 cooling systems LONGITUDINAL Temperature Profile related to the maximum temperatures in iron and in graphite TEMPERATURE[0C] 10 m

  15. Temperature Profile after 200 days of running on the external surfaces of the hadron stop TEMPERATURE[0C] TOP VIEW FRONT VIEW LONGITUDINAL VIEW

  16. CONCLUSIONS  The choice of two cooling systems allows to keep the maximum temperatures under reasonable limits, always below the values accepted for analogous structures used in previous experiments, also in the case of continuos running with the maximum number of protons on target: 13.8x1019 pot/year  Each assumption which has been adopted is referred to the worst case under the thermal point of view the results obtained guarantee that the structure modelled would work in safety conditions under the thermal loading previously specified.

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