F. Regis, 07-04-2011

LINAC4 – LBS & LBE LINES DUMP DESIGN

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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

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LBS & LBE lines

LBS line: Present layout

LBE line

LBS line

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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