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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. - PowerPoint PPT Presentation
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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
ET-2D = Total energy - 2D model=17 kWET-3D = Total energy - 3D model = 16.9 kWDifference < 0.6% negligible for the purpose of the calculations performed
BEAM ENERGY[GeV]
400
NUMBER OFPROTON ONTARGET IN 200DAYS [pot/year]
4.5x1019
MAXIMUM NUMBEROF PROTON ONTARGET IN 200DAYS [pot/year]
13.8x1019
MAXIMUM BEAMPOWER [kW]
512.64
MAXIMUM POWERDEPOSITED IN THEDUMP [kW]
52.13
PURPOSES OF THE BEAM DUMP
Contain in a relatively small volume the radioactivity introduced by the beam particles reaching the end of the decay tunnelShield the detectors from the beam particles reaching the end of the decay tunnelContain 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 GeVContribute to the shield of a possible near detector against muons produced by pions decaying in the decay tunnel
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
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
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-GEOMETRY B-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.
2.6 m 4.0 m 2.8 m
0.2 m
6.0 m
5.0 m 18.2 m
5.0 m
3.0 m
23.8 m
GRAPHITE
ALLUMINUM
AIR
HEAT SINK
CAST IRON
CONCRETE
A-GEOMETRY of the HADRON STOP
TRANSVERSAL SECTION
LONGITUDINAL SECTION
1.3 m 1.6 m 2.0 m1.4 m
3.0 m3.2 m
18.2 m 5.0 m
B-GEOMETRY of the HADRON STOP
TRANSVERSALSECTION
LONGITUDINALSECTION
GRAPHITE
ALLUMINUM
HEAT SINK
CAST IRON
AIR
CONCRETE
5.0 m
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 10 DAYS 5 DAYS
50 DAYS 25 DAYS 100 DAYS 200 DAYS
12 HOURS
TEMPERATURE[0C]
24 HOURS
A-Geometry.Temperature profile on the transversal section related to the maximum temperature reached in graphite after 200 days - 4.5x1019
pot/year
5 DAYS
100 DAYS 200 DAYS
TEMPERATURE[0C]
50 DAYS 10 DAYS
24 HOURS
A- Geometry: load cases studied
Model Load case TmaxGraphite
TmaxCast iron
TmaxAluminum
Withconcrete
4.5x1019
pot/ year110.3 86.4 81.2
Withoutconcrete
4.5x1019
pot/ year110.3 97.1 81.6
Withoutconcrete
13.8x1019
pot/ year298 256 211
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.
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 24 H 5 Days 3 Days 12 H
TEMPERATURE[0C]In 5 days the transient could be considered concluded: the maximum temperature in graphite (194 0C) is reached
10 Days 20 Days 200 Days
Starting from the 10th day, the temperature profile doesn’t change with the time
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
COMPONENT 2 COOLING SYSTEM
TEMP.MAX [0C]
1 COOLING SYSTEM
TEMP.MAX [0C]
Graphite 194 298
Aluminum 108 211
Cast-iron 137 256
Temperature Profile after 200 days of running on the external surfaces of the hadron stop
LONGITUDINAL VIEWFRONT VIEW
TOP VIEW
TEMPERATURE[0C]
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.