june 14-15, 2007/arr 1 trade-off studies and engineering input to system code presented by a. rené...
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June 14-15, 2007/ARR1
Trade-Off Studies and Engineering Input to System Code
Presented by A. René Raffray
University of California, San Diego
With contribution from X. R. Wang
ARIES MeetingGeneral Atomics, San Diego, CA
June 14-15, 2007
June 14-15, 2007/ARR2
Focus of Engineering Effort
- Development of system code including engineering input on various
parameters
- Trade-off studies in conjunction with providing input to system code
June 14-15, 2007/ARR3
Action Items from April 07 Meeting1. Continue system code development including incorporation of engineering input and
cost algorithms (UCSD, PPPL)
2. Provide updated cost algorithms as input to system code (Boeing, UW)
3. Provide blanket definition and parameters (including coupling to power conversion system) as input to system code for DCLL and self-cooled Pb-17Li with SiC/SiC (thermal-hydraulic parameters (UCSD), radial build (UW))
4. Assess impact of heat flux accommodation on choice of materials and grade level of heat extraction for divertor (UCSD, GIT)
5. Provide input on coil material and parameters to system code (MIT)
6. Assess implications of waste treatment on power plant design requirements (UW)
7. Assess impact of power core component design choice on reliability, availability and maintainability (RAM) (Boeing/INL)
8. Evaluate impact impact of tritium breeding and recovery on fuel management, safety and cost (INL /UW)
June 14-15, 2007/ARR4
Power Conversion Trade-Off Studies and Input to System Code
• Impact of coolant temperature on choice of materials and grade level of heat extraction
Coolant Exit temperature (°C): 420 500 620 800 1000
Power Cycle Low-Perf. High- Perf. Braytonconfiguration: Rankine Rankine W-alloy
Possibility of H2
production
Cycle Efficiency: 35% 40% 45% 50% 60%
June 14-15, 2007/ARR5
Example Brayton Cycle Considered
Set parameters for example calculations:- Blanket He coolant used to
drive power cycle- 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 eff. = 0.89- Recuperator effectiv.= 0.95
IP LPHP
Pout
Compressors
RecuperatorIntercoolers
Pre-Cooler
Generator
CompressorTurbine
To/from In-ReactorComponents or Intermediate
Heat Exchanger
1
2
3
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
June 14-15, 2007/ARR6
Brayton Cycle Efficiency as a Function of Neutron Wall Load and Surface Heat Flux for Self-Cooled Pb-17Li + SiCf/SiC Blanket
(based on ARIES-AT)
Constraints:
Max. allowable combined stress = 190 MPa
Max. allowable SiCf/SiC temp. = 1000 oC
Max. allowable CVD Sic temp. = 1000 oC
Turbine efficiency = 0.93
Compressor efficiency = 0.89
Recuperator effectiveness = 0.96
0.45
0.47
0.49
0.51
0.53
0.55
0.57
0.59
0 1 2 3 4 5 6
Average Neutron Wall Load (MW/m2)
Gross Efficiencyq"=0.2
q"=0.3
q"=0.4
q"=0.5
q’’= avg. heat flux (MW/m2)
• Fusion power = 1.74 GW
• Neutron wall load peaking factor = 1.5
• Heat flux peaking factor = 1.25
June 14-15, 2007/ARR7
Brayton Cycle Efficiency as a Function of Neutron Wall Load and Surface Heat Flux for DCLL Blanket
(based on ARIES-CS)
0.424
0.426
0.428
0.43
0.432
0.434
0.436
0.438
0 1 2 3 4 5
Average Neutron Wall Load (MW/m2)
Gross Efficiency
• Fusion power = 2.37 GW
• Neutron wall load peaking factor = 1.5
• Heat flux peaking factor = 1.25
Constraints:
RAFS Tmax<550 oC; ODS Tmax<700 oC
Tmax Pb-17/FS<500 C
Turbine efficiency = 0.93
Compressor efficiency = 0.89
Recuperator effectiveness = 0.95
q’’= avg. heat flux (MW/m2)
0.2
0.4
0.6
June 14-15, 2007/ARR8
Blanket Pumping Power and Brayton Cycle Net Efficiency as a Function of Neutron Wall Load and Surface Heat Flux for DCLL Blanket
(based on ARIES-CS)
1.000E+02
1.500E+02
2.000E+02
2.500E+02
3.000E+02
3.500E+02
0 1 2 3 4 5
Average Neutron Wall Load (MW/m2)
Pumping Power (MW)
3.500E-01
3.600E-01
3.700E-01
3.800E-01
3.900E-01
4.000E-01
4.100E-01
1 2 3 4
Average neutron wall load (MW/m2)
Net Efficiency
q’’= avg. heat flux (MW/m2)
0.2
0.4
0.6
q’’= avg. heat flux (MW/m2)
0.2
0.4
0.6
• Need to confirm pumping power jump for increase of q’’ from 0.4 to 0.6 MW/m2
June 14-15, 2007/ARR9
Impact of Tritium Breeding on Fuel Management, Safety and Cost
• Controllability is a key issue- Need to be able to adjust TBR definitely within 1% and most probably within
0.1%- Even 1% change in TBR results in ~1.5 kg of T per year for a 2.3-3 GW fusion plant- At steady state only need to breed enough to cover decay losses (~0.4%)- Need to be able to provide for initial hold-up inventory and startup inventory of
another reactor (e.g. ~2% for 2 year doubling time)
• TBR is not like your “typical” design parameter (as compared to stress, temperature, dose rate….)
- E.g can overestimate stress to be conservative- If operating stress is as predicted ---> no consequences- If operating stress is lower than predicted ---> still no consequences
- For TBR, overestimating has consequences (what do you do with extra T?)
• Need consistent TBR definition- We should design for an operation TBR (1.01) and show it as such with upper
and lower bound margins
June 14-15, 2007/ARR10
0.5
0.6
0.7
0.8
0.9
1
1.1
1.2
0 20 40 60 80 100
6Li enrichment (%)
TB
R
Uncertainty band in predicting operating TBR(calculation and operation)
Highest confidence estimate within uncertainty range(from experts)
Questions - At which 6Li level
do we start?
- How easy is it to adjust 6Li level
- How long does it take?
- What are the implications on breeder inventory, cost and safety issues?
Example Tritium Breeding Design Operation Point for ARIES-AT
Additional margin for hold-up inventory and/or start-up tritium inventory as required
Design operation TBR (1.01)