F. Regis, LINAC4 – LBS & LBE LINES DUMP DESIGN

 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 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 scenarioLBE 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

5 Dumps features Installation in the tunnel ceiling (≈4.5 m height) d min =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 dump Reduced particle backscattering towards instrumentation LBE Dump Let’s try a common design

6 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 profile Fluka model Courtesy of J. Vollaire 2 months – 12 W 1 month off 2 years – 8h x W 50 cm Upstream (mSv/h) 220 cm in the Soil (mSv/h) Prompt Dose10 3 / h101.00E-03 8h1< 1E-03 1w E-04

7 General Design Features R4550 Graphite Absorbing Core Cu10100 OFE Copper Jacket LBE: commissioning scenario 400 µs Rep. Rate = 1.11 Hz I avg = 40 mA P avg = 2834 W Beam size: vertical measurement scenario Beam parameters

8 Energy deposition Peak energy deposition: 0.833e9 J/m3 Nominal deposited power: 2834 W Total deposited power ≈ 2419 W Peak coordinates: z peak = 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)

9 Thermal analysis Maximum water speed to prevent from erosion/corrosion problem = 1.5 m/s Nominal Heat convection coefficient in cooling pipes = 7157 W/m 2 /K Perfect thermal contact Graphite/Copper Δ T in&out = 0.44 K (1/4 th model) Δ p ss ≈ bar (1/4 th model – straight section only) Steady state – 4 c.p. Vs. 8 c.p. n cp = no. of cooling pipes

10 Thermal analysis Transient analysis – Heat convection efficiency

11 Thermal analysis Absorbing Core – Regime T max Jacket – Regime T max Cooling pipe – Regime T max,wall Nominal convection T max =450°C T max =29°C T max =27°C

12 Structural analysis Mechanical R.T.R 4550Cu Young modulus E (GPa)11.5=f(T) R p02 (MPa) UTS - tension (MPa) UTS - compression (MPa)125- Quasi-Static Structural analysis (worst cooling scenario): First pulse: analysis of stress field in Graphite i th 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

13 Structural analysis 1 st pulse – Stassi criterion Tension1 st pulse – Stassi criterion Compression 500 st pulse – Stassi criterion Tension500 st pulse – Stassi criterion Compression Beam σ max =3.30MPa σ max =3.88MPa σ max =-31.3MPa σ max =-28.72MPa

14 Structural analysis End 1 st pulse – Von Mises 500 st pulse – Von Mises GraphiteCopper Pulse σ T,max σ C,min σ vm,max Stress levels within failure limits for both Graphite and Copper No relevant mechanical properties degradation of Cu10100 (T max = 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 σ max =0MPa σ max =13.5MPa

15 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 WHAT 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

16 LBS Dump: Scenario 1 vs. Scenario 2 L z Magnet z Wall l1l1  H h s1s1 s2s2 s3s3 d/2 d l2l2 l SEM

17 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