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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

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LINAC4 – LBS & LBE Lines dump design

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Presentation Transcript
  • 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
lbs lbe lines
LBS & LBE lines

LBS line: Present layout

LBS line

LBE line

design specifications
Design specifications

LINAC4 Project Document No. L4-B-ES-0001 rev.1.0

LINAC4 standard pulses

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

LBS line operational scenario

LBE line operational scenario

LBS line 1-σ beam size

LBE line 1-σ beam size

dumps features
Dumps features

LBS Dump

  • 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

LBE Dump

LINAC4 full intensity beam (40 mA average current, 2834 W average power)

Most stringent thermo-structural constraints w.r.t. LBS dump

Reduced particle backscattering towards instrumentation

Let’s try a common design

lbs dump rp preliminary analysis
LBS dump: RP preliminary analysis

Irradiation profile

Fluka model

  • 2 months – 12 h/day @142 W
  • 1 month off
  • 2 years – 8h x 2/week @14 W

Induced activity in the water circuit

  • More calculations needed to evaluate concrete thickness necessary to reach 2.5 µSv/h
  • SEM grid position still to be defined
  • Estimated activity based on steady water volume: conservative approach
  • Refined analysis ongoing

Courtesy of J. Vollaire

general design features
General Design Features

Cu10100 OFE Copper Jacket

R4550 Graphite Absorbing Core

Beam parameters

  • LBE: commissioning scenario
    • 400 µs
    • Rep. Rate = 1.11 Hz
    • Iavg = 40 mA
    • Pavg = 2834 W
    • Beam size: vertical measurement scenario
energy deposition
Energy deposition


  • Peak energy deposition: 0.833e9 J/m3
  • Nominal deposited power: 2834 W
  • Total deposited power ≈ 2419 W
  • Peak coordinates: zpeak = 265 mm


  • Peak energy deposition: 0.804e9 J/m3 (-3.5% w.r.tFluka)
  • Total deposited power ≈ 2554 W (+5.6% w.r.t. Fluka)
thermal analysis
Thermal analysis

Steady state – 4 c.p. Vs. 8 c.p.

ncp= no. of cooling pipes

  • 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)
thermal analysis1
Thermal analysis

Transient analysis – Heat convection efficiency

thermal analysis2
Thermal analysis

Absorbing Core – Regime Tmax

Jacket – Regime Tmax



Nominal convection

Cooling pipe – Regime Tmax,wall


structural analysis
Structural analysis
  • 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
  • Dynamic stress - Graphite
  • Heating process slower than stress relaxation due to elastic wave propagation
structural analysis1
Structural analysis

1st pulse – Stassi criterion Tension

1st pulse – Stassi criterion Compression




500st pulse – Stassi criterion Tension

500st pulse – Stassi criterion Compression



structural analysis2
Structural analysis

End 1st pulse – Von Mises


  • Stress levels within failure limits for both Graphite and Copper
  • No relevant mechanical properties degradation of Cu10100 (Tmax = 36°C)

500st pulse – Von Mises

Next steps


Thermal conductance model between graphite core and copper jacket

Definition of the assembly interference (shrink fitting)

Fatigue analysis for the dump – worst case scenario

conclusions and next steps
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 conditions


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

lbs dump scenario 1 vs scenario 2
LBS Dump: Scenario 1 vs. Scenario 2














lbs dump scenario 1 vs scenario 21
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):
    • Scenario 1: more complicated installation. Detailed analysis of dump infrastructure needed.
    • Scenario 2: slot for dump will be drilled. No need for wall partial dismantling.
    • Time of operation: ≈3-5 days.
    • Drilling machine encumbrance: ≈1 m machine width + 1 m on each side.
  • Preliminary discussion with RP (J. Vollaire):
    • Scenario 1: detailed evaluation of soil activation (fluence to TP9 gallery to be checked)
    • Scenario 2: issues about particle fluence to PSB tunnel