Systems analysis of ACT2 design space ARIES UC San Diego UW Madison PPPL Boeing INEL GIT GA M. S. Tillack, with a lot of help from C. Kessel ARIES Project Meeting 21-22 May 2013

Issues and changes to ASC since January Large Scan Issues Had to increase the resolution of integer counter from 6 to 7 digits Maximum length of physics array was increased from 900k to 3M (a segmentation fault occurs when data exceeds the array dimension) Low Power Density Issues The code sets some parameters to zero when out of range, e.g. hth=0. Correction: at low power density, hth should asymptote (0.44 for DCLL) The code sets some parameters to 1030 when out of range, e.g. blanket and divertor pumping power. This is unnecessary. The correlations are probably OK when Pnwl<2 MW/m2, and in any case pump power becomes increasingly irrelevant at low Pnwl. Changed to a warning. Due to the above, plus costing fixes, Many more solutions are now being retained (99% vs. 25%).

Issues and changes since January, continued Costing errors and updates Updates: Added SiC-FCI and W-alloy as selectable materials. Corrected FS (now ODSFS) and RAFS nomenclature ("FS" was previously used incorrectly for RAFS parts in some places) VV steel is now costed the same as RAFS. Errors: The build still has problems, and does not match the current design. The following were artifically eliminated until we can figure it out: 22.1.5 Low Temperature Shield, life of plant: ; nan 22.1.6 Penetration Shielding (low temperature, active and passive): ; nan Mysterious discrepancy: exact same C++ code on 2 different machines leads to different COE. 3-5% differences, yet to be explained.

Three scans were performed using ASC since January 900,573 point scan Difficulty finding a modest R machine nGr and H98 are high-leverage parameters Some parts of parameter space may have been overlooked 1,343,821 point scan Results consistent with initial scan 2,878,320 point scan Finer resolution around 7.25 < BT < 8.75 6.5 < q95 < 9 (higher than earlier scans, giving higher fBS) 8.0 < R < 10.5 More operating points identified in the range 8 < R < 9 m

Filtering is used to make plotting more manageable Start with 2,878,320 physics solutions 2,848,281 of these are retained after ASC run (99%) 2006 survive filtering: 975 ≤ Pnet < 1025 MW R ≤ 10 m fGW ≤ 1.3 H98 ≤ 1.3 qdivob ≤ 15 MW/m2 COE ≤ 100 mills/kWh This smaller number enables analysis within either Excel or VASST

Smaller machines require higher H98 (2009)

8 m machine accessible with fGr=1.2, 9 m machine with fGr=1.1 (2009)

COE increases with BT,max (2009)

COE does not depend much on qdivob (2009)

Sample solutions for ARIES-ACT2 R = 8 m R = 8.5 m R = 9 m 6.25 Physics point 513690 1282721 809775 247203 96837 1361686 355598 97888 1059347 ACT1 H98 1.295 1.298 1.291 1.289 1.241 1.265 1.297 1.278 1.588 fGr 1.3 1.0 btot 3.52 3.23 3.54 3.48 3.24 3.53 3.55 4.75 fBS 0.830 0.861 0.760 0.848 0.819 0.89 Ip (MA) 12.91 12.43 14.12 12.86 12.68 13.06 13.16 13.11 10.93 BT on coil (T) 13.85 15.15 12.76 12.34 14.04 12.99 12.15 12.57 13.8 Precirc (MW) 290 287 384 263 260 293 251 306 350 176 Fusion gain 30.0 22.5 32.5 27.5 25.0 37.5 <Pn> n @FW 2.18 2.14 2.29 1.88 1.83 1.94 1.63 1.72 1.80 2.46 Peak qFW 0.374 0.334 0.464 0.288 0.237 0.284 0.264 0.265 0.271 0.28 Peak qdiv 13.4 13.9 14.4 12.4 13.3 14.0 10.7 12.5 COE (mill/kWh) 71.0 71.6 75.3 72.3 72.1 73.9 76.4 74.8 75.0 66.1

Poloidal field map (time permitting) Final design of power core and PF coils necessitate review of peak fields along LM flow paths. Single loop current at (shifted) plasma center is inadequate, so… A somewhat improved approximation of the distributed plasma current was used. Poloidal field along ducts varies between 1 and 1.5 T with modest gradients (next page).

PF coil field strength mapped onto ACT1 core 0.5 1 0.5