LINAC4 LBE/LBS & MAIN DUMP

CONCEPTUAL DESIGN AND OPEN ISSUES

Ivo Leitão – Linac4 BCC Meeting – 24/11/2011

CONCEPTUAL DESIGN

3

Design Status

Circular cooling pipes - water

cooling

Analytical ModelsParametric

Study

“Optimum” Pre-Design

Pre-Design

Geometry

Materials

Cooling Systems

Cylindrical core

Design

FEM Simulations

Energy DepositionValidation and Refinement of

the Pre-Design

Radio ProtectionTools

Material core: Graphite

Geometry

Materials

Cooling Parameters

Final Design

Phase 1:

Phase 2:

Manufacturing Constrains

4

Common Design (MD, LBE & LBS)

Dump Main Dump LBE LBS

Operational ScenarioReliability Test

(1)Commissioning

(2)Commissioning

(2)

Duration of the Scenario24h/day (6

months)12h/day (2

months)12h/day (2

months)

Kinetic Energy (MeV) 160 160 160

Number of Particles/Pulse 4.99E+13 9.96E+13 4.99E+12

Pulse Length (µs) 400 400 400

Average Current (mA) 20 * 40 ** 40 **

Repetition Rate (Hz) 1.11 1.11 1.11

Mean Power (W) 1421 2834 142

Beam Spot Size (rms) (mm²) 380 95 50

Average Power Density (W/mm²) 3.7 29.8 2.7

Water Flow (L/min) 15 15 15

Pressure Drop (bar) 2 2 2

Maximum Inlet Temperature (˚C)

25 25 25

Common Dump

Kinetic Energy (MeV) 160

Number of Particles9.96E+1

3

Pulse Length (µs) 400

Average Current (mA) 40

Repetition Rate (Hz) 1.11

Mean Power (W) 2834

Beam Spot Size (rms) (mm²) 95

Maximum Water Flow (L/min)

15

Maximum Pressure Drop (Bar)

2

Maximum Inlet Temperature (˚C)

25Worst conditions

Worst conditions (Power & Working Hours)

(1) Before source upgrade (20 mA)(2) After source upgrade (40 mA)

5

Current Conceptual Design

Design restrictions:

Cover

UHV flange

Cooling Jacket

Core

Part Material

Cooling System (Cover & Jacket)

Copper (C10100)

CoreGraphite (R4550)

Safety %20Steering %205Radius Core MainDumpyx

2 ofFactor Safety Length StoppingLength Core Graphite

(General Dimensions - mm)

6

Cooling System

Turbulent Regime

Helical and rectangular ducts improve heat

transferGeometric Relations

Final Parameters

Convection Coefficient (w/m² k)

6580

Pressure Drop (bar) 0.28

b x a (mm) 21 x 8

Number of Turns 12

Mean Temperature (˚C) 26.8

Output Temperature (˚C) 27.6

Flow Velocity (m/s) 1.49

Reynolds Number 20x10³

Input Parameters

c (mm) 20

L (mm) 510

Core diameter (mm) 100

Volumetric Flow (L/min)

15

Maximum Velocity (m/s)

1.5

Water Inlet Temperature (˚C)

25

Power to dissipate (W) 2834

ducts

ducts

N

cNLb

1

PrRe04.0 4.074.0,

(1)

hh DHelicalDNu

smefectiveDissipate TThAP

mTfPropertiesWater

Flow Characteristics

Optimization changing the number of ducts

2012.0Re08.0 25.0(2) RDf hDfanning h

410Re hD

(1) “Heat Exchangers”. H. Martin. Hemisphere Publishing Corporation, (1992).(2) “Fluid Friction and its Relation to Heat Transfer”. C. M. White. Transactions of the Institution of Chemical Engineers, (1932).

7

Contact Interfaces

Contact Model for Interface Copper-Copper (2)

Contact Model for Interface Copper-Graphite (3)

935.0)3( / 3.2464 mEPmkh sc

95.0)2( / 1.25 HPmkh sc

mcoppercopper 1

Interference of 100 µm (diameter) between the Core (Graphite) and the

Jacket (Copper)

Pre-Stress with Interference of 100 µm

(2) “Thermal Contact Conductance of Nominal Flat Surfaces”. H. Yuncu. Journal of Heat and Mass Transfer, (2006).

KkW/m1.75 2ch

KkW/m 8.230 2ch

(3) “Thermal Conductance Models for Joints Incorporating Enhancement Materials”. I. Savija et al. Journal of Thermophysics and Heat Transfer, (2003).

Interface conditions (Pre-Stress Conditions)

mgraphitecopper 1

(4) “An Approximate Thermal Contact Conductance Correlation”. V.W. Antonetti et al. Experimental/Numerical Heat Transfer in Combustion and Phase Change, (1991).

(1) “Fundamentals of Machine Elements”. B. Hamrock et al. McGraw-Hill, (1999).

Thermal Conductance

bar 47.4 AnalyticgraphitecopperP

bar 9.49 AnsysgraphitecopperP

Interference of 100 µm (diameter) between the Core (Graphite) and the

Jacket (Copper) (1)

bar 5.24 AnsysgraphitecopperP

bar 9.49 AnsysgraphitecopperP

111 0

22)1(

giioccicogi

ioiogcgraphitecopper

rrrrErrEr

rrrrEEP

402.0(4) 125.0 m

402.0(4) 125.0 m

Interface conditions (Pre-Stress Conditions)

8

FEM Model Inputs

Pre-Stress, Thermal Conductance and Energy Deposition

Pulse MeV/cm 98.37 3peakE

bar 10 coolingPicHidrodinam

Fixed Support

1tCoefficienFriction

KkW/m 5.89 2ContacthK W/m6580 2Convectionh

(1) Energy Deposition

Interface Copper-CopperCooling System

1.0tCoefficienFriction

KkW/m 4.233 2Contacth

Interface Copper-Graphite

W2834TotalP

m 100ceinterferen i

(1) Thanks to Asen Christov, Vasilis Vlachoudis (Fluka Team)

9

0 50 100 150 200 2500

500

1000

1500

2000

2500

3000

Time (s)

Pow

er

in t

he C

oolin

g

Syste

m (

W)

Thermal Results

0 50 100 150 200 2500

50100150200250300350400450500

Time (s)

Tem

pera

ture

(ºC

)

0 50 100 150 200 25024

24.5

25

25.5

26

26.5

27

Time (s)

Tem

pera

ture

(ºC

)

Temperature at the peak of energy deposition (for 300 shots)

Temperature at the surface of the cooling pipe (for 300 Shots)

Power extracted by the Cooling System (for 300 shots)

For 100 µm of interference

Temperature Field (ºC) (300th shot)

10

Structural Results

For 100 µm of interference

Stassi Stress Ratio Distribution (300th

Shot)

Tension Reference

Tension EquivalentRatio Stress

Ratio Stress

1FactorSafety

Safety Factor (300th shot) = 1.06

Safety Factor (1st Shot) =1.22Pre-

Stress1st Shot 150th

Shot300th Shot

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Stassi

Max. Equ. Stress

Max. Shear Stress

Moht-Coulomb Stress

Str

ess R

ati

o

20 40 60 80 1000

0.2

0.4

0.6

0.8

1

Pre-Stress300th Shot

Diameter Inteference (µm)

Sta

ssi S

tress R

ati

o

20 40 60 80 1000

10

20

30

40

50

Core (Pre-Stress)

Cover (Pre-Stress)

Diameter Inteference (µm)

Pre

ssu

re (

bar)

Parametric Study of Interference

Contact loss

Safety Factor=1.28

Safety Factor=1.06

KkW/m 40 2Contacth

Fatigue?

11

Geometry and cooling system already defined (only few dimensions may change)

Keep going with structural analysis (include fatigue analysis)

Detailed design was started (with Design Office) Results show that beam conditions are a bit “tight” for

LBE, it is possible to increase the beam size? Will the Slit be built? If not, the beam size could be

increased? (LBS~LBE beam conditions).

Conclusions (Conceptual Design)

OPEN ISSUES

13

Radiation Damage

Empirical correlations to relate Dpa with change in materials properties

Energy Particles, e,Temperatur Material,FDpa

Radiation damage is caused by the displacement of atoms from their equilibrium position

Main Dump DurationAccumulated Fluence

(p+/cm²)(Fluence/Total

Fluence)Dpa

(Estimation)Dpa (Fluka) R. Error

Reliability Test 24h over 9 months 3.45E+21 81.6% 1.32 * - -

Commissioning 12h over 3 months 5.75E+20 13.6% 0.22 * - -

Measurement8h twice per week during 20 years

2.05E+20 4.9% 0.08 * - -

Total -- 4.23E+21 100% 1.62 * - -

LBE Dump DurationAccumulated Fluence (p+ /

cm²)(Fluence/Total

Fluence) Dpa

(Estimation)(1) Dpa (Fluka)

R. Error

Commissioning 12h over 2 months 4.08E+20 65.2% 0.16 0.21 24 %

Measurement8h twice per week during 20 years

2.18E+20 34.8% 0.08 0.11 27 %

Total --- 6.26E+20 100% 0.24 0.32 25%

Deterioration of the material properties is usually quantified by (Dpa) Displacements per atom

* Dpa values are being calculated more precisely by the Fluka team

First Estimation of the Dpa (40mA Source):

(1) Thanks to Asen Christov, Vasilis Vlachoudis (Fluka Team)

14

Change in Physical Properties

0 0.005 0.01 0.015 0.02 0.0250

10

20

30

40

50

60

AC-150 - 4R (TA-1) - Radial - 80 (C)

Logarithmic (AC-150 - 4R (TA-1) - Radial - 80 (C))

AC-150 - 4T(AR-1) - Tangential - 80 (C)

Dpa

Vari

ati

on in Y

oung's

Modulu

s (%

)

0 0.025 0.05 0.075 0.1-20

-16

-12

-8

-4

0

AC-150- 10R (TA-1) - Radial - 80 ...

Dpa

Vari

ati

on in C

TE (

%)

0 0.005 0.01 0.015 0.02 0.0250

5

10

15

20

25

AC-150 - 4R(TA-1) - Radial - 80 (C)

Logarithmic (AC-150 - 4R(TA-1) - Radial - 80 (C))

Dpa

Vari

ati

on in C

om

pre

ssio

n

Str

ength

(%

)

0 0.05 0.1 0.15 0.2 0.25 0.3-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6 AC-150 - 4R (TA-1) - Radial - 80 (C)

Logarithmic (AC-150 - 4R (TA-1) - Radial - 80 (C))

AC-150 - 4T (AR-1) - Tangential - 80 (C)

AC-150 - 4A(RT-1) - Axial - 80 (C)

IG-110U - 200 (C)

ETP-10 - 200 (C)

GC-30 - 200 (C)

Dpa

Vari

ati

on in D

imensi

on (

%)

Contact problems / Increase in Pre-Stress?

Increase in elasticity and compression strength ?

“Neutron irradiation effects on the properties of carbon materials”. C. H. Wu et al. Journal of Nuclear Materials. (1994).

“Neutron induced thermal properties changes in carbon fiber composites irradiated from 600 to 1000ºC”. J. P. Bonal and C. H. Wu et al. Journal of Nuclear Materials, (1996).

“Effect of High-Energy Proton Beam Irradiation on the Behavior of Graphite Collimator Materials for LHC”. A. I. Ryazanov et al. Cern, (2010)

15

Change in Physical Properties

0.00001 0.0001 0.001 0.01 0.1 1 100

0.2

0.4

0.6

0.8

1

1.2

AC-150 - 4R(TA-1) - 80 (C)

Logarithmic (AC-150 - 4R(TA-1) - 80 (C))

IG-110U - 200 (C)

ETP-10 - 200 (C)

GC-30 - 200 (C)

FMI 40 - 400 (C)

A05 - Parallel - 400 (C)

5890 Graphite - 400 (C)

A05 - Perpendicular - 400 (C)

DMS 678 - 400 (C)

Polygranular graphite - 500 (C)

Dpa

Therm

al C

onduct

ivit

y Irr

adia

ted / T

herm

al C

onduc-

tivit

y U

n-i

rradia

ted

80-200 C˚

400 C˚

500 C˚

Measurement

Measurement + Commissioning

Measurement + Commissioning + Reliability

Main dump

Measurement

Measurement + Commissioning

LBE dump

If Thermal Conductivity

Temperature

Stresses Creep

Risk of failure

Same references as in the previous slide

16

Actions / Results

Possible actions (Meeting with A. Lombardi and M. Vretenar):

3) Enlarge the beam to 6mm x 8.8mm (rms) (Main Dump)

1) Limit the current to 20 mA during the reliability run

2) Reduce the reliability run to 6 months (Main Dump)

Reduce the accumulated fluence in the center of the core

4) Steerer in front of the dump (Main Dump only) during the reliability run

0 20 40 60 80 100 12020

40

60

80

100

120

Without SteererWith Steerer

Time (s)

Tem

pera

ture

(˚C

)

0 100 200 300 400 5000

20

40

60

80

100

120

Without SteererWith Steerer

z (mm)

Tem

pera

ture

(˚C

)

Temperature at the peak of energy deposition (for 150 shots)

Temperature along the center (for the 150th Shot)

Case study of the Main Dump with 20mA, 6mmx8.8mm beam, with/without steerer after reliability test

?

More calculations needed (structural)

17

Conclusions (Open Issues)

Presented radiation damage study is only a estimative, but indicates possible problems in the future.

Proposed actions should be taken, but the question “Steerer or not” still remains open (more detailed study?)

Should the Main Dump be changed after reliability test and commission? Or wait until (if) it breaks?

Should the Main Dump and its spare be placed inside the shielding and a “changing” mechanism foreseen? Instead of expose technicians to high dose rates?

THANK YOU

Ivo Leitão – Linac4 BCC Meeting – 24/11/2011