linac4 – lbs & lbe lines dump design
DESCRIPTION
LINAC4 – LBS & LBE Lines dump design. F. Regis, 07-04-2011. Outline. LBS and LBE lines Design specifications Dump features LBS dump: RP preliminary analysis General design features Energy deposition Thermal analysis Structural analysis Conclusions and next steps - PowerPoint PPT PresentationTRANSCRIPT
F. Regis, 07-04-2011
LINAC4 – LBS & LBE LINES DUMP DESIGN
2
LBS and LBE lines
Design specifications
Dump features
LBS dump: RP preliminary analysis
General design features
Energy deposition
Thermal analysis
Structural analysis
Conclusions and next steps
LBS dump: Scenario 1 vs. Scenario 2
Outline
3
LBS & LBE lines
LBS line: Present layout
LBE line
LBS line
4
Design specifications
LINAC4 Project Document No. L4-B-ES-0001 rev.1.0
LINAC4 standard pulses
LBS line operational scenario
LBE line operational scenario
LBS line 1-σ beam size LBE line 1-σ beam size
Most severe thermo-structural scenario for LBS dump: Accident
Most severe thermo-structural scenario for LBE dump: Commissioning
For fatigue stress evaluation: most severe duty cycle.Absorbing core diameter: LBE beam size at vertical
measurement, re-scaled at 5-σ
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Dumps features
Installation in the tunnel ceiling (≈4.5 m height)
dmin=200 mm from SEM grid (SEM grid vacuum tank, line
installations, extra-shielding,...)Reduced particle fluence beyond the dump (soil activation issues
and possible effects on TP9 Gallery) Reduced particle backscattering to the SEM grid Feasibility study presented in March 2010 (R. Chamizo, V.
Boccone): starting point
LBS Dump
LINAC4 full intensity beam (40 mA average current, 2834 W average power)
Most stringent thermo-structural constraints w.r.t. LBS dumpReduced particle backscattering towards instrumentation
LBE Dump
Let’s try a common design
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LBS dump: RP preliminary analysis
•More calculations needed to
evaluate concrete thickness
necessary to reach 2.5 µSv/h•SEM grid position still to be defined
Induced activity in the water circuit
•Estimated activity based on steady water
volume: conservative approach•Refined analysis ongoing
Irradiation profileFluka model
Courtesy of J. Vollaire
•2 months – 12 h/day @142 W•1 month off•2 years – 8h x 2/week @14 W
50 cm Upstream (mSv/h) 220 cm in the Soil (mSv/h)Prompt Dose 103/104 1
1h 10 1.00E-038h 1 < 1E-031w 0.1 1.00E-04
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General Design Features
R4550 Graphite Absorbing Core
Cu10100 OFE Copper Jacket
LBE: commissioning scenario• 400 µs• Rep. Rate = 1.11 Hz
• Iavg = 40 mA
• Pavg = 2834 W
• Beam size: vertical measurement scenario
Beam parameters
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Energy deposition
•Peak energy deposition: 0.833e9 J/m3•Nominal deposited power:
2834 W•Total deposited power ≈ 2419
W
•Peak coordinates: zpeak = 265
mm
ANSYS
Fluka
•Peak energy deposition: 0.804e9 J/m3 (-3.5% w.r.t Fluka)•Total deposited power ≈ 2554 W (+5.6% w.r.t. Fluka)
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Thermal analysis
•Maximum water speed to prevent from erosion/corrosion problem = 1.5 m/s•Nominal Heat convection coefficient in cooling pipes = 7157 W/m2/K•Perfect thermal contact Graphite/Copper
•ΔTin&out = 0.44 K (1/4th model)
•Δpss ≈ 0.012 bar (1/4th model – straight section only)
Steady state – 4 c.p. Vs. 8 c.p.
ncp= no. of cooling pipes
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Thermal analysis
Transient analysis – Heat convection efficiency
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Thermal analysis
Absorbing Core – Regime Tmax
Jacket – Regime Tmax
Cooling pipe – Regime Tmax,wall
Nominal convection
Tmax=450°CTmax=29°C
Tmax=27°C
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Structural analysis
Mechanical Properties @ R.T. R 4550 Cu 10100Young modulus E (GPa) 11.5 =f(T)Rp02 (MPa) - 200-240UTS - tension (MPa) 38 240-280UTS - compression (MPa) 125 -
•Quasi-Static Structural analysis (worst cooling scenario):
•First pulse: analysis of stress field in Graphite •ith pulse on regime: global analysis of stress field
•Failure criteria:•Stassi Criterion for Graphite•VonMises Criterion for cooling jacket
99µs
ρE
L
c
L
2
t400µst
c
c0
0dep
•Dynamic stress - Graphite
•Heating process slower than stress relaxation due to elastic wave propagation
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Structural analysis
1st pulse – Stassi criterion Tension 1st pulse – Stassi criterion Compression
500st pulse – Stassi criterion Tension 500st pulse – Stassi criterion Compression
Beam
σmax=3.30MPa
σmax=3.88MPa
σmax=-31.3MPa
σmax=-28.72MPa
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Structural analysis
End 1st pulse – Von Mises
500st pulse – Von Mises
Graphite CopperPulse σT,max σC,min σvm,max
1 3.31 -28.71 0500 3.88 -31.30 13.5
•Stress levels within failure limits for both Graphite and Copper•No relevant mechanical properties
degradation of Cu10100 (Tmax = 36°C)
Thermal conductance model between graphite core and copper jacket
Definition of the assembly interference (shrink fitting)
Fatigue analysis for the dump – worst case scenario
Next steps
σmax=0MPa
σmax=13.5MPa
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Conclusions and Next Steps
A common solution for the LBS and LBE dump seems possible: further analysis
needed
Worst case for thermo-structural analysis have been selected for the LBE dump
Dump configuration has been set according to LBS operation specification
(back-scattering)
Thermal analysis for cooling system design: steady-state and transient state
Structural analysis performed on worst cooling conditionsWHAT IS NEXT?
Thermal conductance model for graphite to copper interface
Refined thermo-structural analysis: assembly interference, ...
Detailed analysis of cooling water activation (RP)
Possible reduction in dump size: open discussion with RP team
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LBS Dump: Scenario 1 vs. Scenario 2
L
zMagnet zWall
l1
H
h
s1s2
s3
d/2dl2
lSEM
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LBS Dump: Scenario 1 vs.Scenario 2
Scenario 1: bending magnet (α=54°) and slit. The LBS dump placed in the tunnel
ceiling.
Scenario 2: bending magnet (α=35°) and no slit. The LBS dump placed in the
tunnel shielding.
First guess dimensions: 1.5 m max. length, 50 cm max diameter.
Preliminary discussion with Civil Engineering (N. Lopez-Hernandez):
1. Scenario 1: more complicated installation. Detailed analysis of dump
infrastructure needed.
2. Scenario 2: slot for dump will be drilled. No need for wall partial
dismantling.
3. Time of operation: ≈3-5 days.
4. Drilling machine encumbrance: ≈1 m machine width + 1 m on each
side.
Preliminary discussion with RP (J. Vollaire):
1. Scenario 1: detailed evaluation of soil activation (fluence to TP9 gallery
to be checked)
2. Scenario 2: issues about particle fluence to PSB tunnel