Update on ARIES ACT2 Power Core Design and Engineering X. R. Wang, M. S. Tillack, C. Koehly ARIES Project Meeting 18 September2013 ARIES UC San Diego UW

Update on ARIES ACT2 Power Core Design and Engineering

X. R. Wang, M. S. Tillack, C. Koehly

ARIES Project Meeting

18 September2013

ARIES

UC San Diego

UW Madison

PPPL

Boeing

INL

GIT

GA

Progress was made in several areas since May

• ACT2 power core configuration and CAD drawings,including blanket internal details

• Primary stress analysis of the reference blanket

• MHD heat transfer in the DCLL blanket, detailed thermal analysis of the steel structures

• Thermal stress analysis of the reference design

• Alternative “small module” blanket concept

o Pressure stress analysis and parametric studies, comparison of small module with full sector blanket

• Power cycle definition

• Next steps

ACT-2 power core CAD drawings (now available on

the web) were generated using physics point 2216814

Plasma major radius 9.75 m

Plasma aspect ratio 4

Plasma minor radius 2.4375 m

SOL at midplane (IB,OB) 10 cm

IB blanket thickness 65 cm

first wall 3.8 cm

breeding zone 58.2 cm

back wall 3 cm

OB-I blanket thickness 40 cm

first wall 3.8 cm

breeding zone 33.2 cm

back wall 3 cm

OB-II blanket thickness 60 cm

front wall 3 cm

breeding zone 54 cm

back wall 3 cm

9 inboard PbLi feed pipes

Definition of the divertor target plates and slots was performed in the same manner as ACT-1

Inboard divertor target to x-Point >~0.48 m

Outboard divertor target to x-Point > ~0.76 m

Internal details were generated based on 3D analysis:

1. Layout and radial build of the reference IB blanketZone Description Thickness (cm)

1 First wall 0.4

2 FW cooling channel 3.0

3 Second wall 0.4

4 Stagnant Pb-Li 0.5

5 SiC insert 0.5

6 Breeding channel 1 26.2

7 SiC insert 0.5


9 Separation plate 1.8


11 SiC insert 0.5


13 SiC insert 0.5


15 Back plate 3.0

Total 65

For R=9.75 m

Breeding cell layout: 9 toroidal, 2 radial

Dimensions of cell:

~0.306 m (toroidal) x 0.291 m (radial)

Thickness of grid plate: 1.8 cm

2. Layout and radial build of outboard Blanket-I

Zone Description Thickness (cm)

1 First wall 0.4


3 Second wall 0.4


5 SiC insert 0.5


7 SiC insert 0.5




11 SiC insert 0.5


13 SiC insert 0.5


15 Back plate 3.0

Total 40

Breeding cell layout: 16 toroidal

Dimensions of OB-I cell:

~0.297 m(tor.)x0.166 m(rad.)

Dimensions of OB-II cell :

~0.31 m(tor.)x0.27 m(rad.)

Thickness of grid plate: 1.8 cm

tor.

pol.

rad.

3. Radial build of outboard Blanket-II

Zone Description Thickness (cm)

1 First wall 0.4


3 Second wall 0.4


5 SiC insert 0.5


7 SiC insert 0.5




11 SiC insert 0.5


13 SiC insert 0.5


15 Back plate 3.0

Total 60

Material compositions of the DCLL outboard blankets from CAD model

(Sector Design)

Material compositions of the DCLL outboard blankets from CAD model

(Sector Design)BOTTOM SECTION MIDDLE SECTION AVERAGE OVER

POLOIDAL LENGTH

Blanket-I(40 cm)

Blanket-II(60 cm)

Blanket-I(40 cm)

Blanket-II(60 cm)

Blanket-I(40 cm)

Blanket-II(60 cm)

Front Plate3.8 cm / 3.0 cm

33.6% F82H 66.4% He(3.8 cm)

46.5% F82H 55.5% He(3 cm)

33.6% F82H 66.4% He(3.8 cm)

38.7% F82H 61.3% He(3 cm)

33.6% F82H 66.4% He(3.8 cm)

42.6% F82H 57.4% He(3 cm)

Breeding Zones33.2 cm (OB-I)54 cm (OB-II)

72.0% LiPb 7.6% F82H8.5% SiC11.9 % He

79.2% LiPb 6.4% F82H7.0% SiC7.4 % He

76.3% LiPb 6.2% F82H7.8% SiC9.7 % He

82.9% LiPb 5.0% F82H6.1% SiC6.0 % He

74.2% LiPb 6.9% F82H8.2% SiC10.7 % He

81.1% LiPb 5.7% F82H6.5% SiC6.7 % He

Back Plate3 cm

74.2% F82H25.8% He

76.3% F82H23.7% He

73.8% F82H 26.2% He

75.1% F82H24.9% He

74.0% F82H 26.0% He

75.7% F82H24.3% He

Load conditions and design limits for primary stress

• Helium operating pressure is 8 MPa

• Pb-17Li static pressure at bottom: ~1.6 MPa front, ~1.5 MPa back(MHD pressure drop of 0.1 MPa was assumed )

• Stress allowables for F82H steel:o Average membrane stress < 1 Sm o Primary membrane plus bending stresses < 1.5 Smt

(2/3 of min. creep stress to rupture)o Thermal stresses < 1.5 Smt

o Combined primary and secondary stresses < 3 Sm

Sm, MPa St, MPa 1.5 Smt, MPa

425 ˚C 152 204 228

450 ˚C 148 180 222

475 ˚C 144 157 216

500 ˚C 139 135 203

525 ˚C 133 112 168

Allowable stress for RAFS (F82H) steel (St at t=100,000 h)

3D stress analysis was performed at several locations

• Primary stress analysis was performed at middle and bottom cross sections for IB, OB1, and OB2

(cf. ARIES-CS, which looked only at one location, and omitted weight of PbLi)

• Boundary Conditions:

a. At bottom plane, z-displacement = 0

b. Free expansion and free bending

c. Symmetry at the vertical plane (poloidal-radial plane at 11.25˚)

Inboard blanket primary (membrane + bending) stress using 1.6 MPa in PbLi, 8 MPa He

Peak stress concentration ~228 MPa

We assume local stress can be reduced (below 216 MPa @475˚C) by adding welding fillers.

We assume local stress can be reduced (below 216 MPa @475˚C) by adding welding fillers.

Rad.

Pol.Tor.

location , MPa

maximum 228

first wall 90

second wall 153

separation plate

144

grid plate 98

back plate 45

Excluding local concentrations, the inboard blanket can accommodate internal pressure up to

2.5 MPa Peak stresses away from local concentrations (that we believe can be

easily fixed)

Limit at 500 C

Limit at 475 C

Allowable pressure

Cross-section at bottom

Cross-section at middle plane

First Wall

Front grid plate

Back grid plate

Separation plate

Back plate

1.5 Smt, MPa @500˚C

Primary stresse at bottom, MPa

73 103 104 124 43 203

Primary stress at middle, MPa

72 98 98 115 45 203

Primary (membrane + bending) stresses in the OB blanket are manageable (1.6 MPa

PbLi pressure)

Modeling of MHD heat transfer is needed to provide heat flux boundary conditions

into steel structures• 2D radial/vertical geometry modeled, including PbLi and SiC

• Boundary temperatures provided by ANSYS; heat fluxes solved iteratively for use in thermal and thermal stress analysis at blanket top and bottom

• Iterative solver used previously for ACT1:

de

dtk

2T

x 2 Q ue

z0

• Peak heat flux (FW) is 0.2805 MW/m2.

• FW He inlet/outlet temperature reduced to 385/436 C (from 429/509), and blanket He exit temperature is ~470 C.

• LiPb inlet/outlet temperature is ~460/647 C.

• Heat transfer coefficient on FW is ~8600 W/m2-K (roughing wall is assumed), ~4300 W/m2-k for all others (smooth walls).

• Maximum structure temperature must be lower than 550 C (thermal creep strength) and LiPb/F82H steel interface must be lower than 500 C (compatibility)

Heat flux from the PbLi breeder into the steel structures can cause interface temperature limits to

be exceeded (kSiC=5 W/mK)W/m2

q1bot 52874

q2bot 39962

q3bot 133430

q4bot 103370

• q > 105 W/m2K can cause difficulty maintaining steel within acceptable temperature range

• k = 2 W/mK provides acceptable temperatures

The highest leverage on grid plate heat flux comes from kSiC

Experiments have been performed on unirradiated SiC foam for flow channel

inserts• In ARIES-ST we assumed kSiC could be easily

degraded

• Recent R&D (Ultramet, Sharafat) suggests 2 W/mK is achievable

Shahram Sharafat, Aaron Aoyama, Neil Morley, Sergey Smolentsev, Y. Katoh, Brian Williams, and Nasr Ghoniem, “Development status of a SiC-foam based flow channel insert, for a U.S.-ITER DCLL TBM,” Fusion Science and Technology 56 (883-891) 2009.

• Uniform inlet temperature = 460 ˚C

• Slug flow

• Zone 1 outlet continues into zone 2, “inside-out”

• kSiC = 2 W/mK

Final thermal results using k=2 W/mK

Zone 1

Zone 2 T1top 491 C

T1bot 488 C

T2top 491 C

T2bot 488 C

T3top 491 C

T3bot 495 C

T4top 491 C

T4bot 495 C

From ANSYS

Thermal stress analysis of OB Blanket-I at bottom section shows requirements are met (kSiC

= 2 W/mK)

• Maximum FW temperature is well below 550˚C limit.

• Maximum LiPb/F82H interface temperature ~495 C (within design limit of 500˚C).

• Maximum thermal stress is ~144 MPa (1.5 Smt=203 MPa at T=500˚C)

144 MPa

W/m2

q1bot 5907

q2bot -4187

q3bot 52657

q4bot 54750

Thermal stresses in outboard blanket-I at the middle section are also well within

limits

133 MPa0.9 mm

Distribution of total deformation

Maximum thermal stress is ~133 MPa, well below 1.5 Sm stress limit (203 MPa at 500˚C)

Distribution of thermal stress

Alternative Blanket Design Option for ACT-2 DCLL (no sector side wall supports)

6 modules/sector

each module is fed by one Pb-Li access pipe

Stress model model

Bottom view

Primary (membrane plus bending) stress for the small blanket (Inner Module) indicates a

minimum of 8 needed6 modules per sector 8 modules per sector

• The inner modules have Pb-Li static pressure balanced on both sides.

• The total stress of the inner module for the case of 8 modules per sector meets 1.5 Smt design limit. The 6 modules/sector design exceeds the allowable stress.

Max. σ=167 MPaMax. σ=167 MPaMax. σ=268 MPaMax. σ=268 MPa

Tor.

Pol.

Rad.

The outer module also meets the 1.5 Sm limit using 8 modules per sector

8 modules per sector (22.5 toroidal degree)

6 modules per sector (22.5 toroidal degree)

Local stressσ= 399 MPa

Local stressσ= 370 MPa

σ= 290 MPa

σ= 199 MPa

6-module design exceeds allowable(1.5 Smt=203 MPa)

Local stress increased a lot vs. sector design, but can be reduced by adding welding fillers.

Local stress increased a lot vs. sector design, but can be reduced by adding welding fillers.

6 modules per sector

8 modules per sector

Parametric studies were performed to explore variations of the FW of the

alternative design

8 module design results in too much steel for TBR

We attempted to find a solution with 6 modules by adjusting the dimensions of the FW channels

38 mm

4 4

20

30

A(reference)

38 mm

4 6

20

28

40 mm

4 4

20

32

B(thick back

wall)

C(thick He channel)

Option A primary stress results (6 modules)

• Allowable primary membrane plus bending stress=203 MPa at T=500 C ͦ

• Allowable total pressure load is ~1.4 MPa

• Option A can not accommodate the weight of Pb-Li (~1.6 MPa).

38 mm

4 4

20

30

Limit at 475 C

Limit at 500 C

• Maintain the total thickness of a FW panel (3.8 cm) unchanged, increase the thickness of the second wall from 4 mm to 6 mm.

• Allowable total pressure load increased from 1.5 to ~2.1 MPa

38 mm

4 6

20

28

Option B primary stress results (6 modules)

Limit at 475 C

Limit at 500 C

• Maintaining the thickness of the second wall unchanged, increasing the total FW panel from 3.8 cm to 4.0 cm (suggested by Siegfried).

• Allowable total load is ~1.5 MPa

40 mm

4 4

20

32

Option C primary stress results (6 modules)

Limit at 475 C

Limit at 500 C

Comparison of Material Compositions for DCLL Inboard Blanket Design

Options

Comparison of Material Compositions for DCLL Inboard Blanket Design

OptionsARIES-CS (2m x 2m module)

ACT2 DCLL(Sector)

ACT2 DCLL(6 Modules-A)

ACT2 DCLL(6 Modules-B)

ACT2 DCLL(6 Modules-C)

ACT2 DCLL(8 Modules)

First Wall3.8 cm

8% ODS FS27% F82H65% He

5.3% ODS FS28.4% F82H 66.3% He

35.5% F82H64.5% He(4/30/4 mm)

39.3% F82H 60.7% He(4/28/6 mm)

37.3% F82H 72.8% He (4/32/4 mm)

35.5% F82H 64.5% He

Breeding Zone58.2 cm

77% LiPb 7% F82H3.7% SiC12.3% He

79.2% LiPb 6.1% F82H6.2% SiC8.5 % He

72.3% LiPb 8.7% F82H5.3% SiC13.7 % He

72.3% LiPb 9.5% F82H5.3% SiC12.9 % He

69.8% LiPb 9.0% F82H5.2% SiC15.3 % He

65.5% LiPb 10.9% F82H5.8% SiC17.8 % He

Back Plate3 cm

80% F82H20% He

84.1% F82H15.9% He

35.6% F82H64.4% He

37.9% F82H 62.1% He

36.8% F82H 63.2% He

35.6% F82H 64.4% He

Max. PrLoad, MPa

(PbLi pressure not considered in ARIES-CS)

2.5 1.4 2.1 1.5 2.3

Maximum primary membrane plus bending stress should be below 1.5 Sm (209/189 MPa for T=500/550 C). The sector design option provides the largest LiPb fraction in the breeding zone and can accommodate the highest

pressure load up to 2.5 MPa. The 6-module per sector design has advantages for fabrication, but lower LiPb fraction in the breeding zone. 6-module A &C options can not support the weight of PbLi. All of the small-module designs have reduced breeding capability.

Brayton cycle efficiency is degraded due to the low inlet temperature required to

maintain steel/PbLi interface below 500 C

operating point, =45%

PbLi

divertor plates

FW

grid

p

late

s

div

ert

or

stru

ctu

re

SR

Power flows and temperature matching in the heat exchanger

We reduced the HX T in order to increase the inlet temperature

What’s next?

• Any revisions based on feedback from this meeting

• We need final PF coil locations ASAP

• A few minor details added in the CAD drawings (e.g. maintenance paths)

• One journal article to be prepared on ACT2 power core engineering

• No work to extend beyond calendar 2013

Documents

Update on ARIES ACT2 Power Core Design and Engineering X. R. Wang, M. S. Tillack, C. Koehly ARIES Project Meeting 18 September2013 ARIES UC San Diego UW