ARIES Project Conference Call

22 October 1997



Participants:
(DOE)Dove
(UCSD) Mau, Miller, Tillack, Wang
(PPPL) Jardin, Reiersen
(GA) --
(UW) El-Guebaly, Khater
(FPA) --
(RPI) Steiner
(ANL) Sze
(BA) Waganer

Administrative

Mark Tillack mentioned that all SOFE presenters should send electronic files of their papers to him so that he can collect them and publish as an ARIES collection. It would also be helpful if you sent HTML files as well so they can be referenced on the WWW site. There has been no additional information regarding the FED special issue.

Les Waganer "volunteered" to collect the inputs for the 9th ARIES progress report. The topic leaders should send drafts to L. Waganer for incorporation.

Ian Cook is hosting the IAEA Technical Committee Meeting on Fusion Power Plant Design to be held at UKAEA Fusion, Culham, UK on 23-27 March 1998. It was confirmed that this will be in place of the regular Japan/US Power Plant Meeting. It is anticipated that ARIES will be well represented, including physics talks.

The next conference call will be on 12 November 1997 (Wednesday at 11:30 CST).

Plasma Physics

Steve Jardin summarized that there has been minimal activity to report since the last meeting. TK Mau noted that he has documented his most recent work in the SOFE paper. Specifically he included new results on MHD stability, current drive, and startup bootstrap overdrive. GA has contributed on the latter topic, with definition of planned startup experiments on DIII-D including PF volt-seconds to help plasma startup.

Engineering

High Heat Flux Components - Mark Tillack noted that if all the anticipated transport power (500 MW) were distributed on the first wall, the surface heat flux on the outboard wall would be 1.6 to 1.7 MW/m2,whereas the ferritic steel wall could be expected to handle only 0.7 to 0.8 MW/m2. Thus, the best assumption is for one-half the transport power be distributed to the (outboard) first wall and the remainder handled by the divertor region (see meeting minutes). A two-meter long (outboard) divertor plate may be possible to distribute the heat flux. The inboard region geometry is unknown until more detailed flux lines are defined. No limiter is assumed on the inboard region. It was reiterated that 20% of transport power goes to the inboard divertor region while 80% is to the outboard (this is only 50% of the total transport power.) There was some discussion of the assumptions on the radiation regions and the radiated flux to the surfaces - Mark Tillack will initiate a simple analysis to determine approximate results. Mark is to contact Ron Stambaugh who had an action item to "Analyze the physics of a diverted plasma and radiative mantle to widen the high heat flux region in the divertor region". Wayne Reiersen volunteered to gather and distribute the K-Star divertor assumptions which may be helpful for our present design.

Mark mentioned that he is still looking at the liquid target designs and the use of highly condensable gases. He is working with the APEX group to help define feasible approaches to the very high heat flux components.

Center Post - Wayne Reiersen questioned if he was to continue with the water-cooled centerpost (CP) or is the liquid metal approach still in the running? Mark reiterated that the two main approaches are the cool and warm water-cooled CP. Gallium is still possible, but other liquid metals seem to have very serious problems and concerns (sodium activates and is very energetic with water). The group needs to document assessment of CP coolants. A lithium-lead CP cooled with helium is also possible if the first wall and blanket were compatible.

Configuration and Maintenance - Mark revealed that the favored maintenance is the vertical approach, but no detailed results were noted. It was requested that the thermal-structural analysis of the A=1.6 strawman design with a bolted joint (both inboard (horizontal maintenance) and outboard (vertical maintenance)) be completed by PPPL before the due date (end of November), if possible, to confirm the feasibility of the vertical maintenance.

Blanket and Thermal Conversion - Dai-Kai noted that organic coolants could not be used in the center post or blanket. Also, the closed-cycle, helium-cooled blanket would have excessive amounts of tritium carried outside the power core to the turbine. It may not be feasible.

Neutronics- It was mentioned that S. Malang voiced concern about the trace amounts of tungsten in the ferritic steel and its impact on the breeding level of the LiPb blanket. Presently, there is 6 wt% W in some commercial steels and the ORNL FS specification lists 2%. With 7.5% ORNL FS structure, the present LiPb blanket design has no breeding problem. Would it be desirable to reduce the W down to 1% to increase the breeding margin? Laila will check with R. Klueh (ORNL) on the effect of the reduction in W on the ORNL FS properties.

Systems Studies

Ron Miller said that he had completed the A=1.8 case, and it is posted on his web site. But he is updating his code and database; thus he is expecting to post new strawmen for all aspect ratios ASAP. Based on the present data, A=1.6 is best and A=1.8 is slightly inferior. Hence the optimal solution seems to be bounded.

Alternate Applications

Les Waganer told the group that most of the effort in this area was preparing and presenting the alternate applications results at the SOFE symposium. Most participants agreed with the results. A few people thought the hybrids were rated too low and should be given better scores.