PbLi Thermofluid Analysis (Session 1 – ITER TBM and blanket design and analysis) Sergey Smolentsev, Siegfried Malang, and Clement Wong FNST MEETING August.

PbLi Thermofluid Analysis(Session 1 – ITER TBM and blanket design and analysis)

Sergey Smolentsev,

Siegfried Malang, and Clement Wong

FNST MEETING

August 12-14, 2008

UCLA

Current accomplishments

• First assessment of MHD pressure drop for the IB blanket - Clement Wong

• Double-Layer Flow Channel Insert for Electric and Thermal Insulation in the Dual-Coolant Lead-Lithium Blanket - this presentation

Double-layer FCI…..Will be presented at TOFE-18

Sept. 28 – Oct. 2, 2008San Francisco, USA

AbstractAbstractAbstract

A new modification of the Flow Channel Insert (FCI) called “double-layer” or “nested” FCI (nFCI) is proposed and assessed via numerical simulations for the poloidal duct flows in the Dual-Coolant Lead-Lithium (DCLL) blanket under the US DEMO OB blanket conditions. The proposed nFCI mitigates the thermal stress while providing sufficient thermal insulation and reducing the MHD pressure drop.

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US DCLL DEMO OB blanketUS DCLL DEMO OB blanketUS DCLL DEMO OB blanket

Sketch of the US DCLL DEMO blanket with the FCI

350/450He inlet/outlet temperature, ˚C

500/700PbLi inlet/outlet temperature, ˚C

3.08Neutron wall loading (peak), MW/m2

0.55Surface heat flux, MW/m2

DEMO OBParameter

The DCLL blanket is considered in the US for testing in ITER and as a primary candidate for a DEMO reactor [1, 2]

In the DCLL blanket, the steel structure is cooled by high pressure He and PbLicirculates slowly (~ 10 cm/s) as a breeder and coolant

A key element of the DCLL concept is the SiCFlow Channel Insert (FCI), which serves as electric and thermal insulator

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StiffeningPlate

Back Plate

He Inlet/OutletPipe

PbLi Inlet/OutletPipe

PbLi InletManifold

PbLi OutletManifold

First Wall

PbLi PoloidalDucts

FCI

PbLiHe

( )pol x

( )rad y

( )tor z

Flow Channel Insert (FCI)Flow Channel Insert (FCI)Flow Channel Insert (FCI) 3

Upper cap FCI

Front duct FCI

Lower cap FCI

Return duct FCI

Inlet manifold FCI

Outlet manifold FCI

Basic FCI configuration in the DCLL OB blanket

The analysis is performedfor FCI in the poloidal flow in thefront duct under DEMO conditions

Potential problem with theconventional single-layer FCI is a large thermal stress associated with the high T in the FCI [3, 4]

Solution 1: Tayloring SiC ( and k)

Solution 2: “Double-layer” (“nested FCI”)

nFCI

B-field

Nested FCI (nFCI)Nested FCI (Nested FCI (nFCInFCI)) 4

(a) (b)

(a) nFCI (basic sketch)(b) nFCI with all plates

atached (model)(c) nFCI with 4 detached

plates (model)(d) nFCI with 1 detached

plate (model)(e) nFCI with one outer

plate (model)

(c) (d) (e)

Mathematical modelMathematical modelMathematical model 5

0

0

1( ) ( ) 0

xxz

tz ty

BBU U dP

z z y y d z

0

0 0

1 1 1 10x x

zy z

B B UB

z z y y z

Momentum equation:

Induction equation:

Energy equation:

p x y z T

T T T TC U k k k q

x x x y y z z

Computational mesh andnFCI flow parameters

Computational mesh andComputational mesh andnFCInFCI flow parametersflow parameters

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z / b

y/b

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5

z / b

y/b

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5

Location of nFCI in thepoloidal duct

Computational mesh concentratesmore points within the nFCI and MHDboundary layers

Gap 1: 1 mmGap 2: 1 mm

FCI 1: 2.5 mm, 10 S/m,1 W/m·KFCI 2: 2.5 mm, 10 S/m,1 W/m·K

Flow velocity = 6.4 cm/sPoloidal length = 2 mToroidal width = 0.207 mRadial depth = 0.211 mMagnetic field = 4 T

Ha=12,000Re=60,000

Velocity (4 detached plates)Velocity (4 detached plates)Velocity (4 detached plates) 7

Induced currentInduced currentInduced current 8

z / b

y/b

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5

z / b

y/b

-0.5 0 0.5

1

z / b

y/b

-1.5 -1 -0.5 0 0.5 1 1.5-1.5

-1

-0.5

0

0.5

1

1.5

z / b

y/b

-0.5 0 0.5

1

4 detached plates All plates are attached

Temperature field (4 detached plates)Temperature field (4 detached plates)Temperature field (4 detached plates) 9

-0 .12 -0.11 -0.1 -0.09y, m

400

500

600

700

800

Tem

pera

ture

, C

PbLi bu lk flow

FC

I 1

FC

I 2

Gap

1

Gap

2

Fe

wal

l

-0 .12 -0.11 -0.1 -0.09z , m

500

550

600

650

700

750

Tem

pera

ture

,C

PbLi bu lk flow

FC

I 1

FC

I 2

Gap

1

Gap

2

Fe

wal

l

Summary of computationsSummary of computationsSummary of computations 10

0.45E-030.59E-030.38E-03dP/dx, MPa/m

~260 K~260 K~260 KOuter FCI (T)y

~150 K~150 K~150 KOuter FCI (T)z

~70 K~70 K~70 KInner FCI (T)z

~50 K~50 K~50 KInner FCI (T)y

126 97 150R

nFCI with 1 detached plate

nFCI with 4 detached plates

nFCI with all plates attached

R is the pressure drop reduction factor = P without FCI / P with FCI

ConclusionsConclusionsConclusions 11

• The new nFCI design provides an engineering solution to mitigate a high thermal stress, which is usually typical to the single-layer FCI. In this design, the thermal insulation is shared between the inner and outer FCI, while the inner FCI provides most of electric insulation.

•The thickness of the FCI layers can easily be adjusted and the choice between one or four detached plates can be made to meet concrete design requirements and heating conditions and, for example, to distinguish between flows in the front and return ducts.

• Compared to the single-layer FCI, electrical conductivity of the outer FCI is of minor importance, and a degradation of its electrical insulation due to cracks or LM filled pores is of no concern.

• Although the present analysis shows significant reduction of the MHD pressure drop in the poloidal ducts of the OB blanket (even in the case of four detached plates), further nFCI optimizations and more analysis may be needed in the IB blanket conditions where the electric insulation requirements are much more demanding.

References:References:References:

[1] C.P.C. Wong, S. Malang, M. Sawan, M. Dagher, S. Smolentsev, B. Merrill, M. Youssef, S. Reyes, D.K. Sze, N.B. Morley, S. Sharafat, P. Calderoni, G. Sviatoslavsky, R. Kurtz, P. Fogarty, S. Zinkle, M. Abdou, An overview of dual coolant Pb-17Li breeder first wall and blanket concept development for the US ITER-TBM design, Fusion Eng. Des. 81 (2006) 461-467.

[2] C. P. C. Wong, S. Malang, M. Sawan, S. Smolentsev, S. Majumdar, B. Merrill, D. K. Sze, N. Morley, S. Sharafat, M. Dagher, P. Peterson, H. Zhao, S. J. Zinkle, M. Abdou, M. Youssef, Assessment of first wall and blanket options with the use of liquid breeder, Fusion Sci. Technol. 47 (2005) 502-509.

[3] S. Smolentsev, N. B. Morley, M. Abdou, MHD and thermal issues of the SiCf/SiC flow channel insert, Fusion Sci. Technol. 50 (2006) 107-119.

[4] S. Smolentsev, N.B. Morley, C. Wong, M. Abdou, MHD and heat transfer considerations for the US DCLL blanket for DEMO and ITER TBM, Fusion Eng. Des., in press (2008).

[5] Y. Katoh, S. Kondo, L.L. Snead, DC electrical conductivity of silicon carbide ceramics and composites for flow channel insert applications, J. Nuclear Materials, in press (2008).

[6] S. Smolentsev, R. Moreau, M. Abdou, Characterization of key magnetohydrodynamic phenomena in PbLiflows for the US DCLL blanket, Fusion Eng. Des., in press (2008).

[7] S. Smolentsev, N. B. Morley, M. Abdou, Code development for analysis of MHD pressure drop reduction in a liquid metal blanket using insulation technique based on a fully developed flow model, Fusion Eng. Des. 73 (2005) 83-93.

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