February 5-6, 2004HAPL meeting, G.Tech.

1

HAPL Blanket Strategy

A. René RaffrayUCSD

With contributions from M. Sawan and I. Sviatoslavsky UW

HAPL MeetingGeorgia Institute of Technology

Atlanta, GAFebruary 5-6, 2004

February 5-6, 2004HAPL meeting, G.Tech.

2

Outline

• Background

• Strategy

• MFE Blanket Options

• Example Trade-Offs

• Summary

February 5-6, 2004HAPL meeting, G.Tech.

3

Background• Distinguish between transient and quasi steady-

state conditions- Separation of armor function and structural + blanket functions

- W armor designed to transient conditions

- Blanket, first wall and cycle designed to quasi steady-state conditions

• Focus HAPL chamber effort on IFE-specific armor/FW issues from the start

• Blanket/system effort starts later (“later is here”)- Make the most of information from MFE

blanket/FW effort.

- At least one credible IFE-specific blanket concept must be developed, compatible with the choice of armor (W) and structural material (FS).

- Chamber configuration needs then be considered in an integrated system context to show that this can lead to a credible and attractive laser IFE power plant.

0

500

1000

1500

2000

2500

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

Time (s)

550

600

650

700

750

800

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5Time (s)

1 mm Tungsten armor

Density = 19350 kg/m3

3.5 mm FS layerCoolant Temp. = 572°C

h =67 kW/m2-K154 MJ DD Target SpectraRep rate = 11.7R=8 m

W/FS interface

FS at coolant

Coolant (h)

FSW

q

February 5-6, 2004HAPL meeting, G.Tech.

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A 2-Phase Strategy is Envisioned

• Participants- UCSD and UW + ad-hoc individual participation

as needed- Close coordination with first wall/armor effort,

Materials Working Group and system studies

HAPL Blanket/FW Effort

Concept I

Choice for detailed design

study

Scoping study of a few

concepts for Laser IFE

Choice for ETF testing

Detailed design study

Input from MFEConcept II

Concept III

Armor/FW Effort

Materials Working

Group

System Studies

Phase I

Phase II

• Phase I: Scoping study (about a year)- Several (2-4) blanket concepts will be developed

to the point where we can intelligently evaluate then in terms of key issues, including:

- Performance, reliability, simplicity, safety and perception from the outside

- Down-selection to one (or perhaps 2) preferred option(s) for more detailed study during Phase II

- First year effort ~ 1 FTE

• Phase II: Detailed design analysis (following year(s))- One (or perhaps 2) preferred option(s) selected

from Phase I- Cover all key aspects to end up with a strongly-

credible and attractive integrated design.- fabrication, operation, maintenance and integration

- Additional effort would be required

February 5-6, 2004HAPL meeting, G.Tech.

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Example of Blanket Concepts Currently Considered for MFE• Structural material: FS or ODS FS• International effort• Concepts cover a range of breeding materials: ceramic breeder, Pb-17Li, Li and flibe

Example Concept SSTR [2] HCPB [5] WCLL [12] DC [10] ARIES-RS [13] FFHR-2 [21]Breeder (form) Li2O or Li2TiO3,

(pebble bed)Li4SiO4 or Li2TiO3

(pebble bed)Pb-17Li Pb-17Li Li FLiBe

Multiplier (form) Be(pebble bed)

Be(pebble bed) -- -- -- Be(pebble bed)

Coolant H2O He H2O Self+He Self SelfStructure F82H (RAFS) FMS FMS FMS V-4Cr-4Ti

+CaO Ins. LayerFS

Struct. Tmax (°C) 550 550 550 550 700 550Struct. Tmin (°C) ~280 300 265 300 330Breeder Tmax (°C) 600 - 900 890 550 700 610 550Breeder Tmin (°C) ~300 400 285 460 330 450Multiplier Tmax (°C) 600 700 -- -- --Multiplier Tmin (°C) ~300 400 -- -- --Coolant Tmax (°C) 320 (520*) 500 325 He : 480 610 550Coolant Tmin (°C) 280 (290*) 250 265 He : 300 330 450Coolant P (MPa) 15 (25*) 8 15.5 14 <1 0.5Max. Neutron WallLoad (MW/m2)

3-5 3.5 5.5 5.0 5.6 1.5

Max. Surf. Heat Flux(MW/m2)

1 0.7 1.0 0.9 0.5 0.1

Energy MultiplicationFactor

1.3 1.39 1.18 1.17 1.21

TBR 1.2 1.11 1.1 1.1 1.1 >1Cycle η (%) ~35 (>40* ) 37 33 45 46 38Structural materiallifetimean dcriteria

> 10 MW-a/m2

100 - 200 dpa15 MW-a/m2

150 dpaswelling

15 MW-a/m2

150 dpaswelling

15 MW-a/m2

150 dpaswelling

15 MW-a/m2

200 dpaembrittlement

15 MW-a/m2

150 dpaswelling

*supercritical-pressure water From A. R. Raffray, et al., “Breeding blanket concepts for fusion and material requirements,” Jour. Nuc. Mat.,307-311 (2002) 21-30

February 5-6, 2004HAPL meeting, G.Tech.

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Several Possible Blanket Concepts from MFE• Resources and time only allow for consideration of 3(or 4) concepts during Phase I

• Some concerns with using water as chamber coolant: - Potential safety issues with Pb-17Li, and/or Li as breeding material and Be as multiplier- Corrosion issues- High pressure- Limited cycle efficiency

• For Phase I, focus on He as coolant and/or self-cooled blanket concepts- Self-cooled Li

- He-cooled ceramic-breeder

- He-cooled or dual cooled Pb-17Li

- Dual or He-cooled molten salt (if possible, but requires more R&D and is lower priority)

- Fully self-cooled Pb-17Li and/or molten salt (flibe) blankets are not included due to their poor heat transfer performances and the difficulty of accommodating IFE heat fluxes

and material constraints with reasonable performance (cycle efficiency) and power densities.

• Above concepts cover a good range of performance and potential risk (e.g. in terms of issues required additional R&D)- Example of such concepts developed for MFE are summarized in the following viewgraphs

February 5-6, 2004HAPL meeting, G.Tech.

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Self-Cooled Li/FS Configuration Adapted from ARIES-AT and ARIES-CS Concepts (presented at last meeting)

Example Li/FS Concept• Lithium provides the advantages of:

– High tritium breeding capability,

– High thermal conductivity,

– Immunity to irradiation damage– Possibility of unlimited lifetime if 6Li

burn-up can be replenished

• Concern includes safety perception

• Simple box-like structure

• 2 blanket regions: first replaceable region and second life of plant region

• Multiple flow passes in the blanket provide the capability for FW surface heat flux ~1 MW/m2

Struc. Tmax<800°C

Cool. Tin/Tout~400/750°C

Cool. P < 1MPa

Cycle Eff. ~46% (Brayton)

Energy Multip. ~1.21

Lifetime =15 MW-a/m2

• Need more detailed neutronics and design integration studies for IFE application

February 5-6, 2004HAPL meeting, G.Tech.

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Example MFE Ceramic Breeder + Be and Ferritic Steel Concept with He as Coolant (EU HCPB Concept)

• CB (Li2TiO3 or Li4SiO4) and Be in form of pebble beds- Good compatibility with FS and He

• 2-mm W armor on first wall

• Modular design- Dimension up to 4m x 2m x 0.8m

- Module box designed to withstand coolant pressurization

- Stiffening grids (~20 cm spacing)

- Breeder unit design compatible with CB or Pb-17Li concepts

Blanket box with stiffening grid and exploded back wall

Blanket breeder unit

Cool. Tin/Tout =300/500°C

Cool. P =8 MPa

Max FS Temp. <550°C

Max. Be Temp. < 750°C

Max CB Temp. <920°

Energy Multip. =1.25

TBR = 1.14

Cycle Eff. ~37% (Rankine)

Lifetime = 15MW-a/m2

February 5-6, 2004HAPL meeting, G.Tech.

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Example MFE Self-Cooled or Dual Cooled Pb-17Li + Ferritic Steel Concept

Example Dual Coolant Concept: FZK DC • Uncouple FW cooling from blanket cooling

– He coolant for more demanding FW cooling (no MHD uncertainties)

– Self-cooled Pb-17Li with SiCf/SiC flow channel insulating inserts for blanket region

– (Note: more flexibility when applying this concept to IFE since there is no MHD effect)

• Use of ODS-steels would allow for higher temperature but more demanding welding requirements

– Compromise: ferritic steel structure with ~mm’s ODS layer at higher temperature FW location

12

12

1

2

1

2Pb-17Li

2

1

He System

Shield

SiCf/SiCChannelInserts

EUROFER Structure(FW+Grids)

ODS LayersPlatedto the FW

• Pb-17Li is an attractive breeder material – Good tritium breeding capability

– Possibility to replenish 6Li on-line

– Almost inert in air

– In general limited extrapolation of blanket technology

• Simplest FS and Pb-17Li concept is a self-cooled configuration (ARIES-ST and FZK DC concepts)

Struc. Tmax=550°C

Pb-17Li Tmax=700°C

He Cool. Tmax/P =480°C/14 MPa

Cycle Eff. =45% (Brayton)

Energy Multip. =1.17

Lifetime =15MW-a/m2

February 5-6, 2004HAPL meeting, G.Tech.

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Blanket Design Procedure

• Develop FW/Blanket concept compatible with FS as structural material and W as armor material- Don’t re-invent the wheel; utilize information from MFE blanket design effort- Consider each concept in series for better focus of group effort

• Self-cooled Li (complete early work) (~ 2-3 months)

• He-cooled ceramic-breeder (~ 3-4 months)

• He-cooled or dual cooled Pb-17Li (~ 3-4 months)

• Dual or He-cooled molten salt (if possible, but lower priority)

• Comparative assessment and selection (~ 1 month)

- Maximize performance• Choose power cycle providing highest efficiency for expected coolant temperatures:

Brayton or Rankine cycle• Maximize cycle efficiency for given material constraints

- Design simplicity as a measure of reliability • Minimize welds, channels, joints and coolant pressure (if possible)

- Adequate tritium breeding

February 5-6, 2004HAPL meeting, G.Tech.

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Example comparison illustrated next

Blanket Scoping Study Will Also Help to Better Understand and Appreciate the Trade-Offs between Different Blanket

Characteristics as Applied to IFE

• High performance v. lower performance options- Mostly linked with maximum coolant temperature that can be achieved within

design constraints

- Choice of power cycle (Brayton v. Rankine)

- Final assessment through system studies

• Self-cooled v. separately cooled options- Combining heat removal and breeding functions v. separation of functions

• Liquid breeder v. solid breeder options- Safety impact and perception of using Li or Pb-17Li v. Be (required with CB

blankets to achieve tritium breeding goal)

- Other issues for both classes of concepts

February 5-6, 2004HAPL meeting, G.Tech.

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Example Rankine Cycle for Use with Chamber Coolant via Heat Exchanger

• Superheat, single reheat and regeneration (not optimized)

• For example calculations, set:

- Turbine isentropic efficiency = 0.9

- Compressor isentropic efficiency = 0.8

- Min. (Tcool–Tsteam,cycle) > 10°C

- Pmin = 0.15 bar

S

T

2

3

4

56

8'

7

reheat

superheat

Pmax

Pint

4'

8

9

Pmin

2'

10

10'

1

m

1-m

Tcool,in

Tcool,out

February 5-6, 2004HAPL meeting, G.Tech.

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Effect of Constraint on (Tcool–Tsteam,cycle) < 10°C

BB

BB B

B

B

J

J

J

J J J

J

H H H H

H

H H

F F F F F F F

0

0.1

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0.5

0

20

40

60

80

100

120

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400 500 600 700 800Blanket Coolant Outlet Temperature (°C)

ΔTHX

(Pinch Point, 3)

ΔTHX

(7)

ΔTHX

(9)

S

T

2

3

4

56

8'

7

reheat

superheat

Pmax

Pint

4'

8

9

Pmin

2'

10

10'

1

m

1-m

Tcool,in

Tcool,out

February 5-6, 2004HAPL meeting, G.Tech.

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Rankine Efficiency and Corresponding Water Pressures as a Function of Coolant Outlet Temperature for Example Rankine

Cycle

BB

BB B

B

B

JJ

J

JJ

J

J

H H H H HH

H

F F F F F F F0

0.1

0.2

0.3

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0

40

80

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400 500 600 700 800Blanket Coolant Outlet Temperature (°C)

Pmax

Pint

Pmin

February 5-6, 2004HAPL meeting, G.Tech.

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Example Brayton Cycle Considered

Set parameters for example calculations:- T between coolant and He in

HX= 50°C- Minimum He temperature in

cycle (heat sink) = 35°C - 3-stage compression - Optimize cycle compression

ratio (but < 3.5; not limiting for cases considered)

- Cycle fractional P ~ 0.07- Turbine efficiency = 0.93- Compressor efficiency = 0.89- Recuperator effectiveness = 0.95

IP LPHP

Pout

Compressors

RecuperatorIntercoolers

Pre-Cooler

Generator

CompressorTurbine

To/from In-ReactorComponents or Intermediate

Heat Exchanger

1

2

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4

5 6 7 8

9 10

1BPin

TinTout

η ,C ad η ,T ad

εrec

5'

1

22'

38

9

4

7'9'

10

6

T

S

1B'

1B

February 5-6, 2004HAPL meeting, G.Tech.

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Comparison of Brayton and Rankine Cycle Efficiency as a Function of IFE Chamber Coolant Temperature (under previously described assumptions)

B

B B B B BJ

J

JJ J

J

H

HH

HH

H

F

FF

FF

F

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1 1 1

0.2

0.3

0.4

0.5

0.6

100

200

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900

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300 400 500 600 700 800 900 1000110012001300

Blanket Coolant Outlet Temperature (°C)

B

J

H

F

1

Brayton

Brayton

Blanket Cool. Inlet Temp.for Rankine Cycle:

200°C

250°C

300°C

350°C

400°C

• For blanket concepts to be considered, the max. coolant temperatures from past studies are:

- Li: ~750°C- Pb-17Li: ~700°C- Ceramic breeder/He: ~ 500°C

• These values are illustrative and will probably change when applied to our IFE case

• Still they fall close to the region where at higher temperature it is clearly advantageous to choose the Brayton cycle and at lower temperature the Rankine cycle

• The choice of cycle would need to be made on a case by case basis and confirmed through the system studies

February 5-6, 2004HAPL meeting, G.Tech.

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Summary

• A 2-phase strategy is envisioned for the HAPL blanket effort- Phase I: Scoping study of 3-4 concepts over the first year- Phase II: Downselect to 1 (or 2) concepts for more detailed study

• Blanket effort will be carried out in close coordination with other chamber effort (armor/FW and system) and MWG

• Make the most of information from MFE blanket design effort

• Consider each concept in series for better focus of group effort- Self-cooled Li (complete early work) (~ 2-3 months)- He-cooled ceramic-breeder (~ 3-4 months)- He-cooled or dual cooled Pb-17Li (~ 3-4 months)- Dual or He-cooled molten salt (if possible, but lower priority) - Comparative assessment and selection (~ 1 month)

• Team is assembled, strategy has been laid out….we are ready to go!