Impact of Advances in Fusion Physics & Technology on the Attractiveness of Tokamak Power Plants

Impact of Advances in Fusion Physics & Technology on the Attractiveness of Tokamak Power PlantsFarrokh NajmabadiUniversity of California San Diego

22th annual meeting of Japan Society of Plasma Science & Nuclear Fusion ResearchDecember 1, 2005

Electronic copy: http://aries.ucsd.edu/najmabadi/ARIES Web Site: http:/aries.ucsd.edu/ARIES

Framework:Assessment Based on Attractiveness & FeasibilityPeriodic Input fromEnergy IndustryGoals and RequirementsEvaluation Based on Customer AttributesAttractivenessCharacterizationof Critical IssuesFeasibilityBalanced Assessment ofAttractiveness & FeasibilityNo: RedesignYes

Elements of the Case for Fusion Power Were Developed through Interaction with Representatives of U.S. Electric Utilities and Energy IndustryHave an economically competitive life-cycle cost of electricityGain Public acceptance by having excellent safety and environmental characteristicsNo disturbance of publics day-to-day activities No local or global atmospheric impactNo need for evacuation planNo high-level wasteEase of licensingReliable, available, and stable as an electrical power sourceHave operational reliability and high availabilityClosed, on-site fuel cycleHigh fuel availabilityCapable of partial load operationAvailable in a range of unit sizes

A dramatic change occurred in 1990: Introduction of Advanced TokamakOur vision of a fusion system in 1980s was a large pulsed device.Non-inductive current drive is inefficient.Some important achievements in 1980s:Experimental demonstration of bootstrap current;Development of ideal MHD codes that agreed with experimental results.Development of steady-state power plant concepts (ARIES-I and SSTR) based on the trade-off of bootstrap current fraction and plasma b (1990)ARIES-I: bN= 2.9, b=2%, Pcd=230 MW

Directions for ImprovementImprovement saturates at ~5 MW/m2 peak wall loading (for a 1GWe plant).A steady-state, first stability device with Nb3Sn technology has a power density about 1/3 of this goal.

Evolution of ARIES Designs

1st Stability, Nb3Sn Tech.ARIES-IMajor radius (m)8.0b (bN)2% (2.9)Peak field (T)16Avg. Wall Load (MW/m2)1.5Current-driver power (MW)237Recirculating Power Fraction0.29Thermal efficiency0.46Cost of Electricity (c/kWh)10

Reverse Shear Option

High-FieldOptionARIES-I6.752% (3.0)192.52020.280.498.2

ARIES-RS5.55% (4.8)164810.170.467.5

ARIES-AT5.29.2% (5.4)11.53.3360.140.595

ARIES-I Introduced SiC Composites as A High-Performance Structural Material for FusionExcellent safety & environmental characteristics (very low activation and very low afterheat).High performance due to high strength at high temperatures (>1000oC).Large world-wide program in SiC:New SiC composite fibers with proper stoichiometry and small O content.New manufacturing techniques based on polymer infiltration or CVI result in much improved performance and cheaper components.Recent results show composite thermal conductivity (under irradiation) close to 15 W/mK which was used for ARIES-I.

Continuity of ARIES research has led to the progressive refinement of researchStarlite & ARIES-RS:Li-cooled vanadiumInsulating coatingARIES-ST: Dual-cooled ferritic steel with SiC insertsAdvanced Brayton Cycle at 650 oCARIES-AT: LiPb-cooled SiC composite Advanced Brayton cycle with h = 59%

Advanced Brayton Cycle Parameters Based on Present or Near Term Technology Evolved with Expert Input from General Atomics*Key improvement is the development of cheap, high-efficiency recuperators.

Chart5

850565.1141069182872.5264028727

900594.2945353916922.8569335776

950623.1112021245973.00088364

1000651.57987089191022.9166118708

1050678.29732022081072.5843829725

1065687.71862207261087.0461265155

1080696.11810695341102.2856182468

1100707.2777346731121.3145693947

Maximum He temperature

Minimum He temperature

Maximum LiPb temperature

Gross Efficiency

Temperature (C)

Brayton Cycle He Inlet and Outlet Temperatures as a Function of Required Cycle Efficiency

Data

THERMAL-HYDRAULIC CALCULATIONS FOR HE-COOLED LIPB BLANKETREFERENCE

BRAYTON CYCLE CALCULATIONS

Cycle Temperatures

Max. He Temperature, Tmax(=T1) (K)11231173122312731323133813531373

Max. He Temperature, Tmax(=T1) (C)85090095010001050106510801100

Cycle Lowest He Temperature, Tmin (=T4=T6=T8)(K)308

Cycle Lowest He Temperature, Tmin (=T4=T6=T8)(C)35

Tmax/Tmin3.64610389613.80844155843.97077922084.13311688314.29545454554.34415584424.39285714294.4577922078

Helium

gamma, Cp/Cv1.66

gamma-1/gamma0.3975903614

Fractional Pressure Losses

Recuperator (each side)0.01

Inter-Cooler (each)0.0025

Heat Rejection HX0.005

Total out-vessel0.03

Blanket0.00982211650.01029319440.01077610490.01127165010.01176731920.01187875810.01209344470.0122085498

ITERATION WITH LINE 184 BELOW IN ITERATION SHEET

Efficiencies

Recuperator0.96

Turbine0.93

Compressor (each)0.9

Compressor

Compression ratio per compressor1.29219189481.3029800551.31357991211.32400203911.33611567241.33776380071.34075240831.3446335862

Turbine

Pressure ratio2.07306795412.12441392322.17562165152.22670265772.28723435292.29544998272.31036662962.3302172131

Pressures

P1 (blanket outlet, turbine inlet) (MPa)

Temperatures

T9 (Recuperator inlet, cold) (K)308308308308308308308308

T2 (Turbine outlet) (K)860.2021947065890.5984743663920.6158355464950.2706988457978.10137523987.9152313256996.66469474311008.289306951

T10 (Blanket Inlet) (K)838.1141069182867.2945353916896.1112021245924.5798708919951.2973202208960.7186220726969.1181069534980.277734673

T10 (Blanket Inlet) (C)565.1141069182594.2945353916623.1112021245651.5798708919678.2973202208687.7186220726696.1181069534707.277734673

Overall Efficiency

Parameter A152.6436775932168.4833113788184.7858059546201.5299055007219.5351384196224.1564944624229.3839500003236.4327542953

Gross Cycle Efficiency0.53580637480.55112953770.56528644340.57841062750.59062027360.59413612110.59753782130.6020355227

Comparable Carnot Efficiency0.72573463940.73742540490.74816026170.7580518460.76719576720.76980568010.77235772360.7756737072

POWER PARAMETERS INPUT

ARIES-RS Power Parameters

Fusion Power (MW)2171

330

Alpha Power (MW)434.2

Neutron Power (MW)1736.8

Neutron Multiplication Factor1.26

Total Thermal Power (MW)2622.568

4.03

5.67

0.4

0.47

5

39.4

55.4

Advanced Power Reactor

ARIES-RS X

From Neutronics Calculations

5

6.5

OB Ratio of Average to Maximum Wall Load0.85

IB Ratio of Average to Maximum Wall Load0.73

Fusion Power (MW)2170

Alpha Power (MW)434

Neutron Power (MW)1736

Neutron Multiplication Factor1.1

Current Drive Power (MW)50

Total Thermal Power (MW)2393.6

8.5

7.225

5.6

4.088

0.6

0.705

7.5

36.125

42.5

FIRST WALL HE FLOW AND SIC MAX. TEMPERATURE CALCULATIONS

He as FW Coolant

FW He Inlet Temp. (FROM BRAYTON CYCLE CALC.)(C)565.1141069182594.2945353916623.1112021245651.5798708919678.2973202208687.7186220726696.1181069534707.277734673

Maximum He FW Temperature Rise at Outboard Midplane(C)150

Average Outboard He FW Temperature Rise(C)127.5

Maximum He FW Outlet Temperature at Outboard Midplane(C)715.1141069182744.2945353916773.1112021245801.5798708919828.2973202208837.7186220726846.1181069534857.277734673

Average Temperature at Outboard Midplane (C)640.1141069182669.2945353916698.1112021245726.5798708919753.2973202208762.7186220726771.1181069534782.277734673

FW He Inlet Pressure (MPa)20

Properties based on Ave. Bulk Temp. at Midplane Outboard

1.07E+011.03E+011.00E+019.75E+009.50E+009.41E+009.34E+009.24E+00

Heat Capacity (J/kg-K)5.19E+03

Thermal Conductivity (W/m-K)3.38E-013.46E-013.54E-013.61E-013.68E-013.71E-013.73E-013.76E-01

Dynamic Viscosity (kg/m-s)4.33E-054.43E-054.53E-054.62E-054.71E-054.74E-054.77E-054.81E-05

Prandtl Number6.65E-016.65E-016.65E-016.65E-016.65E-016.65E-016.65E-016.65E-01

SiC Composite

3200

Fractional Theoretical Density0.95

Young's Modulus (GPa)360

Poisson's ratio0.16

Thermal Expansion Coeff. (ppm/C)4.4

k in plane (W/m-K)25

k through thickness (W/m-K)20

First Wall

SiC/SiC Tube thickness (m)0.001Plasma

Tube Diameter (m)0.006

SiC Tube Spacing (m)0.001

Armor thickness (CVD SiC) (m)0.002CVD SiC Armor

Tube Poloidal Pitch (m)0.009SiC/SiC tubes

Back side SiC/SiC thickness (m)0.004

Toroidal Tube Length (m)0.75

Module poloidal length (m)6

Radial Module Thickness (m)0.75

L/D3.75E+02SiC/SiC

Roughness (m)5.00E-06

2.00E+00

FW Region Radial Thickness (m)1.40E-02

FW Region He Volume Fraction2.24E-01

FW SiC Volume Fraction7.76E-01

Maximum Thermal Power per Tube

From surface heat flux (MW)0.00475875

0.000080343

From neutron nuclear heating (MW)0.0025609331

Additional fractional heat flux from LiPb at the back of the FW0.06434269110.07185375950.07963301340.08770633790.09652700650.10057583060.10134844640.1079543731

ITERATION WITH LINE 272 BELOW IN ITERATION SHEET

Maximum thermal power per tube unit cell (MW)0.00779065120.00784562990.00790257150.00796166570.00802623020.00805586630.00806152160.0081098749

Maximum Helium Flow Rate

3.54E+023.56E+023.59E+023.62E+023.64E+023.66E+023.66E+023.68E+02

Helium maximum velocity (m/s)3.31E+013.44E+013.57E+013.71E+013.84E+013.89E+013.92E+013.99E+01

Heat Transfer Coefficient

Re Number4.90E+044.82E+044.75E+044.69E+044.64E+044.63E+044.60E+044.60E+04

1.14E+021.12E+021.11E+021.10E+021.09E+021.08E+021.08E+021.08E+02

6.41E+036.47E+036.54E+036.61E+036.67E+036.70E+036.71E+036.76E+03

Max. film drop (C)129.9294946649128.6166617703127.3212480066126.0391585313124.7526376269124.2217801769124.0077425131123.2270994904

7.80E+028.09E+028.37E+028.65E+028.91E+029.00E+029.08E+029.19E+02

9.26E+009.01E+008.79E+008.57E+008.38E+008.31E+008.25E+008.18E+00

Thermal Conductivity (W/m-K)3.75E-013.82E-013.90E-013.97E-014.03E-014.05E-014.07E-014.10E-01

Dynamic Viscosity (kg/m-s)4.80E-054.89E-054.99E-055.08E-055.16E-055.19E-055.21E-055.25E-05

Prandtl Number0.6645760.6645760.6645760.6645760.6645760.6645760.6645760.664576

Re Number4.42E+044.37E+044.32E+044.27E+044.24E+044.23E+044.21E+044.21E+04

1.05E+021.04E+021.03E+021.02E+021.01E+021.01E+021.01E+021.01E+02

6.54E+036.60E+036.67E+036.73E+036.80E+036.82E+036.83E+036.88E+03

FW He Max. film drop (C)127.2884471626126.0881714983124.8975633249123.7134008044122.5161622802122.017674082121.8255283878121.0857301923

Max. SiC Temperature

Approx. Max. SiC/SiC Temp. Rise (C)4.06E+01

Approx. CVD SiC Max. Temp. Rise (C)7.48E+01

SiC/SiC Max. Temp (C)8.83E+029.11E+029.39E+029.66E+029.91E+021.00E+031.01E+031.02E+03

CVD SiC Max. Temp (C)9.58E+029.86E+021.01E+031.04E+031.07E+031.08E+031.08E+031.09E+03

Approximate 1-D Thermal Stress in SiC

Thermal stress (Pa) in SiC1.09E+08

FW Pressure Drop

Darcy-Weisbach friction factor for rough tubes0.07347210880.07406102410.07461446310.0751328210.07556169480.07567618190.07587931090.0759460505

FW He Pressure Drop (MPa)0.17321550440.18263748510.19229602650.20220719390.21211736650.21595352470.21855729230.2237347618

Separator Wall He Pressure Drop from 310 below (MPa)0.0030030390.0040940970.00536697630.00686085540.00865523110.00952030710.00976098720.011213872

Outboard Manifold Pressure Drop (MPa)2.33E-02

He Total Blkt Pres.Drop (greater of 180 and 181,+manifold DP) (MPa)1.97E-012.06E-012.16E-012.26E-012.35E-012.39E-012.42E-012.47E-01

He Fractional Pressure Drop9.83E-031.03E-021.08E-021.13E-021.18E-021.20E-021.21E-021.24E-02

ITERATION WITH LINE 22 ABOVE IN ITERATION SHEET

OVERALL BLANKET He FLOW RATE

0.0401715

0.04397652

Avg. power generation in SiC FW per outboard module (MW)4.288651785

Total avg. thermal power per outboard module34.617375

Outboard FW Region Fractional Thermal Power0.13185850120.13278902690.13375277730.13475295940.13584572790.13634732560.13644304280.137261433

ITERATION TO FIND SIC SEPARATOR WALL FRACTIONAL POWER

Outboard Fractional SiC separator thermal power (consistent with line 272)1.56E-011.94E-012.33E-012.73E-013.17E-013.38E-013.41E-013.74E-01

Total Outboard He Region Fractional Thermal Power2.88E-013.27E-013.67E-014.08E-014.53E-014.74E-014.78E-015.12E-01

TOTAL FW + Sep. Thermal Power (assuming same fract. power in inboard and outboard)(MW)6.90E+02782.9215434276877.8116372725976.6932878971084.69953138711134.78760258891.14E+031224.409912581

Effective He region temperature rise (C)1.70E+021.74E+021.77E+021.79E+021.82E+021.83E+021.83E+021.84E+02

Effective SiC He outlet temperature (C)7.35E+027.68E+028.00E+028.31E+028.60E+028.70E+028.79E+028.91E+02

Total FW + Sep. He Flow Rate (kg/s)7.84E+028.69E+029.57E+021.05E+031.15E+031.20E+031.20E+031.28E+03

HE TMIX and CYCLE HE FLOW RATE

Effective He inlet temp. to IHX after mixing (C)6.47E+026.94E+027.43E+027.94E+028.47E+028.67E+028.79E+029.08E+02

Brayton Cycle He flow rate (kg/s)1.62E+031.51E+031.41E+031.32E+031.24E+031.22E+031.20E+031.17E+03

HE PUMPING POWER

First, Calculate Brayton Cycle Pressures

P1 (blanket outlet, turbine inlet) (MPa)19.803473630419.794051649819.784393108419.77448194119.764571768319.760735610219.758131842619.7529543731

P2 (turbine outlet) (MPa)9.55273732899.31741758679.0936735698.88061181978.64125346128.60865440738.55194651348.4768725687

P3 (recuperator outlet, heat rejection inlet) (MPa)9.45720995569.22424341089.00273683338.79180570158.55484092658.52256786328.46642704828.392103843

P4 (1st stage compressor inlet) (MPa)9.40992390589.17812219378.95772314928.7478466738.51206672198.47995502398.4240949138.3501433238

P5 (1st stage compressor outlet,1st intercool. inlet) (MPa)12.159427401811.95891016111.76668518711.582166833211.373105751811.344176862111.294625542711.2278831629

P6 (2nd stage compressor inlet, 1st intercool. outlet) (MPa)12.129028833311.929012885611.73726847411.553211416111.344672987411.315816419911.266388978811.199813455

P7 (2nd stage compressor outlet, 2nd intercool. inlet) (MPa)15.673032750215.54326586615.417840090415.296475473615.157795376815.137889581415.105438156715.0596453309

P8 (3rd stage compressor inlet, 2nd intercool. outlet) (MPa)15.633850168415.504407701315.379295490215.258234284915.119900888415.100044857515.067674561315.0219962175

P9 (3rd stage compressor outlet) (MPa)20.201934472120.201933999720.201933618320.201933307120.201936542320.200293398620.202020956120.1990806461

P10 (recuperator outlet, blanket inlet) (MPa)19.999915127419.999914659719.999914282119.99991397419.999917176919.998290464620.000000746519.9970898396

2.86E+012.85E+012.84E+012.83E+012.82E+012.82E+012.82E+012.82E+01

FW + Sep. Wall He Pumping Power based on FW flow only (MW)5.97E+006.96E+008.05E+009.27E+001.06E+011.12E+011.15E+011.23E+01

FW + Sep. Wall He Pumping Power based on total cycle flow (MW)1.23E+011.21E+011.19E+011.17E+011.15E+011.14E+011.14E+011.13E+01

Total Cycle loss He Pumping Power (MW)3.83E+013.62E+013.42E+013.25E+013.09E+013.05E+013.02E+012.96E+01

LiPb CALCULATIONS

Intermediate (LiPb/He) HX Effectiveness0.9

He inlet temp. to IHX (C)6.47E+026.94E+027.43E+027.94E+028.47E+028.67E+028.79E+029.08E+02

He outlet temp. from IHX (=Tmax Brayton)(C)85090095010001050106510801100

Assume (mCp)He

Originally developed for ARIES-ST, further developed by EU (FZK).Typically, the coolant outlet temperature is limited to the max. operating temperature of structural material (550oC for ferritic steels).A coolant outlet temperature of 700oC is achieved by using a coolant/breeder (LiPb), cooling the structure by He gas, and SiC insulator lining PbLi channel for thermal and electrical insulation.

ARIES-ST Featured a High-Performance Ferritic Steel Blanket

ARIES-AT2: SiC Composite BlanketsSimple manufacturing technique. Very low afterheat.Class C waste by a wide margin.LiPb-cooled SiC composite divertor is capable of 5 MW/m2 of heat load.Innovative design leads to high LiPb outlet temperature (~1,100oC) while keeping SiC structure temperature below 1,000oC leading to a high thermal efficiency of ~ 60%.

Outboard blanket & first wall

Innovative Design Results in a LiPb Outlet Temperature of 1,100oC While Keeping SiC Temperature Below 1,000oC Two-pass PbLi flow, first pass to cool SiCf/SiC box second pass to superheat PbLi

The ARIES-AT Utilizes An Efficient Superconducting Magnet DesignOn-axis toroidal field:6 TPeak field at TF coil:11.4 TTF Structure: Caps and straps support loads without inter-coil structure;Superconducting MaterialEither LTC superconductor (Nb3Sn and NbTi) or HTCStructural Plates with grooves for winding only the conductor.

Use of High-Temperature Superconductors Simplifies the Magnet SystemsHTS does offer operational advantages:Higher temperature operation (even 77K), or dry magnetsWide tapes deposited directly on the structure (less chance of energy dissipating events)Reduced magnet protection concerns

Modular sector maintenance enables high availabilityFull sectors removed horizontally on railsTransport through maintenance corridors to hot cells Estimated maintenance time < 4 weeksARIES-AT elevation view

Our Vision of Magnetic Fusion Power Systems Has Improved Dramatically in the Last Decade, and Is Directly Tied to Advances in Fusion Science & Technology

Radioactivity Levels in Fusion Power PlantsAre Very Low and Decay Rapidly after ShutdownFerritic SteelVanadium

Fusion Core Is Segmented to Minimize the Rad-Waste

Generated radioactivity waste is reasonable1270 m3 of Waste is generated after 40 full-power year (FPY) of operation (~50 years)Coolant is reused in other power plants29 m3 every 4 years (component replacement)993 m3 at end of serviceEquivalent to ~ 30 m3 of waste per FPYEffective annual waste can be reduced by increasing plant service life.

Chart1

320

340

120

200

150

140

Cumulative Compacted Waste Volume (m3)

Sheet1

BlanketShieldVacuum VesselMagnetsStructureCryostat

320340120200150140

Sheet2

Sheet3

Advances in plasma physics has led to a dramatic improvement in our vision of fusion systems Attractive visions for tokamak exist. The main question is to what extent the advanced tokamak modes can be achieved in a burning plasma (e.g., ITER):What is the achievable bN (macroscopic stability)Can the necessary pressure profiles realized in the presence of strong a heating (microturbulence & transport)Pace of Technology research has been considerably slower than progress in plasma physics.Advanced technologies have a dramatic impact on attractiveness of fusion. Considerable more technology R&D is needed.

Documents

Impact of Advances in Fusion Physics & Technology on the Attractiveness of Tokamak Power Plants