ENGINEERING DESIGN AND TRANSIENT FLUID DYNAMIC … · first generation of ess moderators (bf2)mrs tik3.1 design solution & status manufacturing final assembly ndt’s ready for delivery!

ENGINEERING DESIGN AND TRANSIENT FLUID DYNAMIC SIMULATIONS OF

THE SECOND GENERATION OF LOW DIMENSION COLD MODERATOR FOR

THE EUROPEAN SPALLATION SOURCE ESS

2019-10-15 I ICANS XXIII, CHATTANOOGA I Y. BEßLER, G. NATOUR

OUTLINE

1. ESS Moderator & Reflector System status

2. First generation of ESS Moderators (BF2)

3. BF1 vs. BF2

4. Design criteria and solution

5. Heat deposition

6. Material properties

7. Start conditions of CFX

8. Uncertainties

9. Simulation results

10. Validation of simulation results

11. Outlook Red: Jülich deliverables

ESS MODERATOR & REFLECTOR SYSTEMPROJECT OVERVIEW

Moderator & Reflector Unit

Shaft & mountingSocket & MRP

Frames (shielding) Final twister assembly

Crown

Axial bearing

Shaft

Frame

Bucket

Rotation Unit

Twisterweight: 13 tHeight: 6,5 m

MRS TIK3.1

Cold Moderators

Thermal Moderator

Irradiation module

Pre Moderator

FIRST GENERATION OF ESS MODERATORS (BF2)DESIGN SOLUTION & STATUS OF MANUFACTURING

MRS TIK3.1FIRST GENERATION OF ESS MODERATORS (BF2)DESIGN SOLUTION & STATUS MANUFACTURING

Final assembly

NDT’s

Ready for delivery!

BF1

BF2

BF1 MODERATOR VS. BF2 MODERATOR, [1]WHY NEW DESIGN BEFORE THE OLD ONE IS IN USE?

• Minimal structure material content (neutronic)

• Material, location and time-dependent neutronic heat

• Pressure pm≈10 bar (pd=17 bar)

• Temperature Tm≈18,5 K (dT≤3 K)

• >99,5% para hydrogen

• Consideration of irradiation

• Compressibility of LH2

• Avoid (local) boiling

• RCC-MRx calculation

• Manufacturability

• Weldability

• …….7

BF1 MODERATOR STUDYDESIGN CRITERIA

8

BF1

Second generation of ESS

cold Moderators…..

BF1 MODERATOR DESIGN SOLUTION, [2]

Manufacturing concept

36 m

m

Cold Neutrons

Fast Neutrons

≈1l para LH2 volume

Dimensions: 250 x 200 x 36

Structural material Al6061-T6

𝑟 = y2 + 𝑧2

BF1 MODERATORHEAT DEPOSITION =F(MATERIAL,X,Y,Z), [2]

𝑟 = y2 + 𝑧2

0

2

4

6

8

10

12

14

16

18

20

22

24

26

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0

Gi(t)

=q

P∙q

i/qm

ax

[-]

t [ms]

Weighting factor for the time-dependent heat

qLH2

qm

qAl

BF1 MODERATORHEAT DEPOSITION =F(MATERIAL,X,Y,Z,T), [2]

0

50

100

150

200

250

300

0,0 1,0 2,0 3,0 4,0 5,0

qV

m(t

) [W

/cm

3]

t [ms]

Average volumetric heat in the pulse

qH2P

qAlP

qH2m

qAlm

11

BF1 MODERATORSTART CONDITIONS OF CFX, [2]

12

0,1

1

10

100

1000

10 15 20 25 30 35 40

log

p [b

ar]

T [K]

Phase diagram of para H2

GasLiquid

Solid

critical. point

0

20

40

60

80

100

120

140

160

0 50 100 150 200 250 300

λ[W

/mK

]

T [K]

Thermal conductivity of aluminum 6061-T6

λ

λirrad

BF1 MODERATORMATERIAL PROPERTIES, [2]

13

BF1 MODERATORUNCERTAINTIES OF HEAT DEPOSITION, [2]

1. Mass flow control valves! (∑ei≈ ±1%)

2. Outlet pressure control of PCB and pressure sensor! (∑ei≈ ±3,5%)

3. Inlet Temperature control of HX and temperature sensor (∑ei≈±2,5%)

4. Manufacturing Tolerance using for CFX the max wall thickness!

5. Material properties comparison with other libraries (∑ei≈ ±1%)

6. CFX??? experiment (PIV)

14

BF1 MODERATORADDITIONAL UNCERTAINTIES, [2]

15

25

27

29

31

33

35

37

39

41

43

0 20 40 60 80 100 120 140 160 180 200

T [K

]

Iteration-No. [-]

Temperature

T-AL-MAX T-AL-MAX-AVE T-H2-MAX T-H2-MAX-AVE

BF1 MODERATORSS RESULTS (TEMPERATURE), [2]

Heat averaged over time!(results used as start condition for pulsed simulation)

16

9,7

9,8

9,9

10,0

10,1

10,2

10,3

10,4

10,5

10,6

0 20 40 60 80 100 120 140 160 180 200

p [b

ar]

Iteration-No. [-]

Pressure

p-MIN p-AVE p-MAX p-IN

BF1 MODERATORSS PRE RESULTS (PRESSURE), [2]

Heat averaged over time!(results used as start condition for pulsed simulation)

17

0

5

10

15

20

25

30

0 1 2 3 4 5

Gi(t)

[-]

t [ms]

Time steps

0

1

2

3

4

5

6

7

8

0 200 400 600 800 1000 1200 1400

dt [m

s]

No. [-]

Time stepping

BF1 MODERATORTIME DISCRETIZATION (TIME STEPPING), [2]

18

1600 Time steps, 20-50 iterations each 128 CPU’s, Simulation time ≈70 h

0

10.000

20.000

30.000

40.000

50.000

60.000

70.000

80.000

90.000

0 200 400 600 800 1.000 1.200 1.400 1.600

q [W

/s]

t [ms]

Heat pulse at 1, 3 and 5 MW P-beam power

Heat-Al Heat-H2

BF1 MODERATORHEAT INTEGRAL VALUES, [2]

>109 Load changes per lifetime

19

-0,4

-0,2

0,0

0,2

0,4

0,6

0,8

1,0

0,0

0,5

1,0

1,5

2,0

2,5

0 200 400 600 800 1.000 1.200 1.400

dp [b

ar]

dT

[K

]

t [ms]

dT and dp at 1, 3 and 5 MW P-beam power

BF1 MODERATORDT, DP, [2]

20

17

19

21

23

25

27

29

31

33

35

0 200 400 600 800 1.000 1.200 1.400

T [K

]

t [ms]

Temperature at 1, 3 and 5 MW P-beam power

T-IF-MAX T-IF-AVE T-H2-AVE T-H2-OUT T-H2-IN T-AL-AVE T-Al-MAX

BF1 MODERATORTEMPERATURE DISTRIBUTION, [2]

Without any uncertainties!TB=31,24 K; TMAX=30,75

BF1 MODERATORPRELIMINARY RESULTS OF PARTICLE IMAGE VELOCIMETRY MEASUREMENT (PIV), [2]

-0,1

0,0

0,1

0,2

0,3

0,4

0,5

20 21 22 23 24 25 26 27

vy

[m/s

]

x [mm]

MP3-PIV

MP3-CFX

0,0

0,1

0,2

0,3

0,4

0,5

-26 -24 -22 -20 -18 -16 -14 -12 -10 -8

vy

[m/s

]

x [mm]

MP4-PIV

MP4-CFX

Comparison of the velocity profiles (left) and mean velocities (right) in the measuring Points [PIV (blue) and CFX (green)]

-25

-20

-15

-10

-5

0

5

10

15

20

1 2 3 4 5 6 7 8

vm,u

m[m

/s]

MPi [-]

Measured and simulated mean velocities as a function of MPi at Re=8,4∙105 (=ESS Moderator)

BF1 MODERATORPRELIMINARY RESULTS OF PARTICLE IMAGE VELOCIMETRY MEASUREMENT (PIV), [2]

23

15

17

19

21

23

25

27

29

31

0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0 5,5 6,0 6,5

TIF

-MA

X[K

]

Pm [MW]

Interface temperature as a function of the proton beam power

TB(pmin) T-IF-MAX(Pm)

P-Beam+

MCNPX

Boiling temperature TB=f(p)

Estimated CFX error

(preliminary)

BF1 MODERATORMAX “THEORETICAL” BEAM POWER (PRELIMINARY RESULTS), [2]

• Design and CFX simulation of BF1 Moderator are completed!

• Comparison with PIV measurement is still in progress

• Max Proton beam power will be around ≈4MW (based on current requirements)

• For 5 MW local boiling can occur (possible cavitation needs to be analyzed)

• Prototyping will be completed in January

• PhD thesis will also be published in January

OUTLOOK

SOURCES

[1] Zanini, L., et al. The neutron moderators for the European Spallation Source. Oxford : 22nd meeting of the

International Collaboration on Advanced Neutron Sources (ICANS XXII), 2017

[2] Bessler, Yannick. Strömungsmechanische Simulation und experimentelle Validierung des kryogenen

Wasserstoff Moderators für die Europäische Spallationsneutronenquelle ESS.

Unpublished PhD, RWTH Aachen.

[3] europeanspallationsource.se

Y. Beßler Seite 25

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