Thrust 11 ChitID 11.001 Bruce Lipschultz 6/08/2009 14:45 Thrust 11 - There is almost no basis for use of P/R as a scaling parameter. I suggest dropping the reference to that and leave the scaling from ITER (x5 power through the separatrix if no additional radiation in the pedestal). - In addition to the various divertor options mentioned I believe just increasing divertor area a la expanded boundary makes sense. It is probably simpler to achieve than the various divertor options mentioned. ChitID 11.002 Bruce Lipschultz 6/08/2009 15:38 Thrust 11 - This and other thrusts argue that Li is compatible with the high temperature walls one wants for thermal conversion efficiency in a reactor (550-1000C). I can possibly be convinced that people will be clever and be able to get the Li to flow across the magnetic field. On the other hand I find it difficult to believe that the erosion rate of Li won't be enormous. Please define what the gross erosion rate is for Li as a function of temperature and compare to C and W. Some estimate of the net erosion both in the divertor and first wall would be good too. ChitID 11.003 David Hill 6/09/2009 13:10 Thrust 11 Seems like 10 and 11 both aim to develop solutions to the PFC issues, one looking at the materials and one looking at divertor configurations. Seems like ideal candidates for consolidation using definition of thrust: multi-faceted attack on an important issue for fusion. ChitID 11.004 David Hill 6/09/2009 13:14 Thrust 11 Impact of naturally occurring SOL currents on liquid metal divertors should be considered. ChitID 11.005 Clement Wong 6/09/2009 13:31 Thrust 11 Based on the presentation: Good presentation with focus on the divertor design. In the 6 pager, please make sure that discussion on the issues of cooling the FW is included. The FW is removing >80% of the thermal power for DEMO and at the same time the heat flux distribution is uncertain. For coolant heat transfer enhancement approach, the use of internal channel roughening should be included for the FW design. At the same time, the combination of internal channel roughening and other methods like jets should be included in future development. It is too early to narrow on a few selected helium-cooled heat transfer enhancement options. University programs can sure make contributions in helium-cooled heat transfer enhancement in the future. ChitID 11.006 Hantao Ji 6/09/2009 13:33 Thrust 11 Free-surface liquid metal flow in a magnetic field is a relatively unexplored area of research. What are properties of MHD turbulence of such flow, including flow drag and heat transport? I suggest that in addition to the comprehensive test stand described in the thrust, I suggest to add a research component on these basic physics understandings using a combination of theory, simulation and small-scale experiments. This component is important to give us a firm base for any further applications to fusion environments. ChitID 11.007 Hantao Ji 6/09/2009 14:12 Thrust 11 With regard to basic properties of free-surface liquid metal flows, there are quite some details that have been worked in Thrust #13 where liquid metal duct flows were described. There are important commonalities with free-surface MHD. I recommend to interact with that thrust on these aspects. ChitID 11.008 Dennis Youchison 6/09/2009 15:32 Thrust 11 Limit thrust#10 activities to PMI (first 10 microns of pfc surface) Thrust #11 should address power and particle effects deeper than 10 microns. ChitID 11.009 Richard Buttery 6/09/2009 15:42 Thrust 11 Principal of divide between 10 and 11 seems OK, but practically there are clear overlaps - eg on transients and needs for integrated test facilities in each thrust. Need to draw line more carefully... Should materials part of thrust 10 be merged into a new nuclear+heat materials thrust with 14 - and rest of thrust 10 into 11? >> ONE STRONG THRUST TO RESOLVE MATERIALS. ChitID 11.010 Clement Wong 6/10/2009 07:52 Thrust 11 VG #1 The Thrust has the wrong title, because the need is much more than innovations. It gives the wrong impression to the reader and the authors of the thrust, leading to too much on innovation and not enough on basics. Suggest simply calling it Improved Power and Particle Handling, or Innovative and Broad base Development of Power and Particle Handling. ChitID 11.011 sam cohen 6/10/2009 11:25 Thrust 11 Add statements in this thrust how some alternate confinement devices, e.g. FRC and spheromkas, offer opportunities for innovations in energy extraction while stellarators have even more constraints. ChitID 11.012 Alice Ying 6/11/2009 10:38 Thrust 11 Originally submitted via email Tue, 09 Jun 2009 17:58 Eastern time (EH) Two distinct power handling concepts (LM and He-cooled)were mentioned in this thrust. Is the author?s intent to develop both concepts simultaneously? Are there criteria to be used to differentiate one concept from the other in terms of R&D strategy and time line? ChitID 11.013 Clement Wong 6/11/2009 12:07 Thrust 11 Originally submitted to thrust 99 on 6/10/09 8:00 VG #1 The Thrust has the wrong title, because the need is much more than innovations. It gives the wrong impression to the reader and the authors of the thrust, leading to too much on innovation and not enough on basics. Suggest simply calling it Improved Power and Particle Handling, or Innovative and Broad base Development of Power and Particle Handling. VG # 2 The presentation and therefore corresponding writing needs to identify deficiencies in PFC development including necessary helium test loops, test stands, fabrication with RAFM steel, CCGT and robust and disruption tolerant (both thermal and structural effects) PFC designs. We also need to include design margins. ChitID 11.014 Clement Wong 6/11/2009 12:08 Thrust 11 VG # 3 On the disadvantages, the list should also indicate that the piping arrangement which is especially difficulty for the FW and inboard components. This helps to highlight the difficulties in designing for large FW components while meeting all the routing, heat removal and low pumping requirements. VG # 6 Under innovation should add “twisted tapes” and “2-D and 3-D surface roughening”. Actually there could be other new and combination of options. VG # 7 For a major cooling option for fusion power development, VG # 7 actually indicates the inadequacy of helium cooled development and limited development participants in the last 16 years, mostly from SBIR, which naturally focused on break through innovations like refractory alloys and porous media. A much broader base and fundamental support, like from universities and industries will be needed. ChitID 11.015 Clement Wong 6/11/2009 12:09 Thrust 11 VG # 8 All refractory metal heat sink…is not the correct indicator of necessary development. We will need a refractory metal surface and even the indicated examples shown later have transitional piece to RAFM steel or ODFS. A more straightforward option of planar refractory metal surface e.g. W, joining to ODFS and then RAFM steel and then to coolant channels should be considered for both FW and divertor designs. For lower temperature helium coolant at ~350-400 C, the ODFS is to bring the surface temperature up to 700 C such that the W surface could be maintained to >700 C, which is necessary to maintain the toughness of the W-alloy under neutron irradiation. VG # 20 Recommendations should add the need for broader base support and to enhance the training of a new generation of heat removal engineers and scientists.