![Page 1: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/1.jpg)
Overview of the ARIES-ACT2 Power Core
M. S. Tillack and X. R. Wang UC San Diego
US/Japan Workshop on Power Plant Studies and Advanced Technologies
13-14 March 2014
ARIES
UC San Diego
UW Madison
PPPL
Boeing
INEL
GIT
GA
![Page 2: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/2.jpg)
ACT2 characteristics affecting design choices 1. The ACT2 plasma provides modest steady-state loads:
• Peak/average neutron wall loading Pnw = 2.2/1.5 MW/m2
• Peak divertor surface heat flux qdiv < 10 MW/m2
• Peak FW heat flux qfw = 0.28 MW/m2
2. A “conservative” DCLL blanket was explored by our Team for the first time in an integrated tokamak power plant configuration. • ARIES-ST (spherical torus) • ARIES-CS (compact stellarator) • US ITER TBM (small test articles) • He-cooled RAFS structure (e.g. F82H), PbLi in SiC inserts
3. He-cooled W-alloy divertor was chosen as the only known option that meets requirements on safety, waste & performance.
4. Brayton power cycle is possible with η~45% (350˚C blanket inlet) 2
![Page 3: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/3.jpg)
ACT2 uses traditional ARIES full-sector maintenance concept: components contained in a structural ring
3
![Page 4: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/4.jpg)
The reference blanket is related to ARIES-ST
4
• 550˚C limit for steel, 500˚C limit for steel/PbLi interface.
• 8 MPa He cools the FW toroidally (385-436˚C) and grid plates vertically (470˚C).
• 0.28 MW/m2 peak heat flux and 2.2 MW/m2 peak wall load result in low thermal stresses.
• 2 W/mK SiC insulators (FCI’s) allow PbLi temperature to exceed 550˚C.
• Simple LM flow paths keep primary stresses low.
• Complete thermal, fluid and elastic stress analyses were performed.
![Page 5: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/5.jpg)
An alternative blanket design concept was explored in an attempt to simplify the manufacturing
each module is fed by one Pb-Li access pipe
Bottom view
![Page 6: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/6.jpg)
6
Comparison of reference design and small-module design
ARIES-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 Wall 3.8 cm
8% ODS FS 27% F82H 65% He
5.3% ODS FS 28.4% F82H 66.3% He
35.5% F82H 64.5% 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 Zone 58.2 cm
77% LiPb 7% F82H 3.7% SiC 12.3% He
79.2% LiPb 6.1% F82H 6.2% SiC 8.5 % He
72.3% LiPb 8.7% F82H 5.3% SiC 13.7 % He
72.3% LiPb 9.5% F82H 5.3% SiC 12.9 % He
69.8% LiPb 9.0% F82H 5.2% SiC 15.3 % He
65.5% LiPb 10.9% F82H 5.8% SiC 17.8 % He
Back Plate 3 cm
80% F82H 20% He
84.1% F82H 15.9% He
35.6% F82H 64.4% He
37.9% F82H 62.1% He
36.8% F82H 63.2% He
35.6% F82H 64.4% He
Max. Pr Load, MPa
(PbLi pressure not considered in ARIES-CS)
2.5 1.4 2.1 1.5 2.3
• The main penalty of the small-module design is increased steel fraction (and reduced PbLi), requiring adjustments to maintain TBR.
• Modifications to the FW design allowed us to use 6-module concept.
![Page 7: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/7.jpg)
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
• Option B gave the best results (2.1 MPa max PbLi pressure)
A (reference)
B (thicker
back wall)
C (thicker
He channel)
![Page 8: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/8.jpg)
Engineering analysis of the reference blanket
8
MHD heat transfer
ANSYS thermofluid
3D primary stress
3D primary plus thermal
stress
Component energy balance
Power cycle
neutronics neutronics
![Page 9: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/9.jpg)
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:
![Page 10: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/10.jpg)
Structures remain within their limits, with a modest variation from front to back
10
• Assumed flow “inverts” due to U-bend at top
![Page 11: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/11.jpg)
0.0E+00
2.0E+04
4.0E+04
6.0E+04
8.0E+04
1.0E+05
1.2E+05
1.4E+05
1.6E+05
0 1 2 3 4 5 6
Hea
t Flu
x, W
/m2K
SiC conductivity, W/mK
Q3top
Q3bot
Q4top
Q4bot
Q1top
• q > 105 W/m2K can cause difficulty maintaining steel within acceptable temperature range
• k = 2 W/mK provides acceptable temperatures
• Recent R&D (Ultramet, Sharafat) shows this is achievable
The highest leverage on grid plate ���heat flux comes from kSiC
![Page 12: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/12.jpg)
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)
![Page 13: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/13.jpg)
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.
Rad.
Pol. Tor.
location σ, MPa maximum 228 first wall 90 second wall 153 separation plate 144 grid plate 98 back plate 45
![Page 14: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/14.jpg)
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)
0
50
100
150
200
250
1 1.5 2 2.5
Prim
ary
Mem
bran
e Pl
us B
endi
ng S
tres
s, M
Pa
Pressure Load, MPa
First Wall Second Wall Separation Plate Grid Plate
Design pressure
Limit at 500 C Limit at 475 C
Allowable pressure
![Page 15: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/15.jpg)
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) • Similar results at top and mid-plane
144 MPa
W/m2
q1bot 5907 q2bot -4187 q3bot 52657 q4bot 54750
![Page 16: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/16.jpg)
The plate divertor concept provides acceptable performance with mimimum complexity
16
Plate ~1 m 104
T-tube ~10 cm 105
Finger ~1.5 cm 106
(results for 600/700˚C He inlet/outlet temperature)
![Page 17: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/17.jpg)
300.0"
400.0"
500.0"
600.0"
700.0"
800.0"
0%" 20%" 40%" 60%" 80%" 100%"
Tem
pera
ture
(C)"
Power Transferred"
PbLi"
divertor plates"
FW"
grid
pla
tes"
dive
rtor s
truct
ure"
SR"
Power flows and HX temperatures are consistent with all power core inlet/outlet temperatures
![Page 18: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/18.jpg)
0"
100"
200"
300"
400"
500"
600"
43%"
44%"
45%"
46%"
47%"
48%"
1.6" 2.1" 2.6" 3.1" 3.6" Pow
er C
ore
Inle
t Tem
pera
ture
(C)"
Eff
icie
ncy
Compression Ratio
Efficiency"
"Inlet Temperature""
Brayton cycle efficiency is degraded 2.5% due to the low inlet temperature required to maintain
steel/PbLi interface below 500 C
operating point, η=45%
![Page 19: Overview of the ARIES-ACT2 Power Core · 2014. 3. 13. · ACT2 characteristics affecting design choices! 1. The ACT2 plasma provides modest steady-state loads:! • Peak/average neutron](https://reader035.vdocuments.us/reader035/viewer/2022071000/5fbc53a260e4bb53c124e9c1/html5/thumbnails/19.jpg)
Summary and Conclusions • The modest loading conditions in ARIES-ACT2 allow the DCLL
blanket to easily satisfy materials requirements. However, ���PbLi technologies must be further developed and demonstrated.
• The moderate divertor loading allows us to use the simpler He���plate-type divertor. However, W-alloy development is a critical issue. Advanced (high temperature) steel alloys are also needed.
• An alternative, “small module” design was proposed. However, ���further studies are needed to demonstrate fabricability (including manifolds) and acceptable performance.
• Much progress has been made on design details. However, more effort will be needed on design detauils and fabricability in order to implement in a next-step device such as FNSF.
• The ACT2 power core is a reasonably conservative design that meets the design requirements and provides an attractive 45% conversion efficiency.