Starlite Conference Call Minutes

29 November 1995

Participants: Sze, Wong, Herring, Bathke, Waganer, Lee, Jardin, Steiner, Miller, Najmabadi, Mau, Tillack, El-Guebaly

Administrative

- The 25-27 October 1995 Starlite Project Meeting Minutes have been reviewed and published on the WWW Starlite Home Page.
- The Fourth Quarterly Report has been posted on the Starlite Home Page, no comments noted.
- The 15 November Engineering Group Conference Call minutes have been reviewed and posted on the Starlite Home Page. The Physics Group held a conference call on 28 November and the results are summarized in these minutes
- F. Najmabadi is working on the project schedule and milestones and hopes to have a draft out in two weeks.
- The dates of the next Starlite project meeting were confirmed as 31 January-2 February (until noon) at San Diego. These dates will coincide with the conclusion of the bulk of analyses and documentation on the Low Aspect Ratio Demo and Commercial Power Plant. It was decided to invite the LAR advocates to meet with the Starlite team one day of the meeting to review our preliminary results and exchange information.
- It was decided to return to six meetings per year to improve the project productivity and technical interchange. To obtain reduced airline ticket prices, the next meeting was tentatively set for 27-29 March, also at San Diego.
- UCSD will host a U.S./Japanese workshop on March 10-15. Only a limited set of the Starlite team need attend. This is separate from our normal 18-month Reactor Studies workshop exchange with Japan which will be held in the fall of 1995 in San Diego.
- There has been no feedback regarding the project letter sent to Anne Davies summarizing the progress of the project and possible future work emphasis. Farrokh will distribute the letter to executive committee.
- Status of outstanding reports - Chapters can be sent to authors for review if requested.

- ARIES-II/IV Figures in several sections still needed + review
- ARIES- III In review at UCSD
- PULSAR Some figures and subsections still missing
- Stellarator Hoping to finalize and publish soon

PROJECT ACTIVITIES

Assessment Phase Report (1995) - F. Najmabadi just issued a preliminary outline of the report with section author assignments. The report is to cover the systems, physics, and engineering assessments for several reactor concepts including pulsed, 1st stability, 2nd stability, reversed shear, and low aspect ratio. There was a great deal of discussion as to how the report should be structured-by concept or type of analysis. Also discussed was how much information should be repeated in this assessment report that was or will be presented in the concept final reports, e.g. PULSAR. The recommendation was to generally take out any duplication of prior work associated with pulsed-plasma (PULSAR), 1st stability (ARIES-I), and 2nd stability (ARIES II-IV) unless it is new work conducted in 1995 and not reported in those prior reports. So there will be a Physics section (with systems support) comparing the plasma regimes. An Engineering section will summarize work on the related hardware options, with more effort devoted to the reverse shear and the low aspect ratio, as the other options had been investigated in the prior studies. The ferritic steel and vanadium assessments will be included in this engineering section. The materials properties appendix is still missing from both reports [inputs needed from Billone]. Tillack and Waganer need to review the vanadium assessment for missing figures and references. The report will also include the work accomplished in economics and costing (ref. Miller's IEEE paper), safety and licensing, and RAMI (inputs from T. Flynn). The final two major sections will be devoted to a more in-depth assessment of the reversed shear and the low aspect ratio power plants. F. Najmabadi will issue a revised outline incorporating the recommendations [done 11/29/95]. Report inputs are to be completed and forwarded to UCSD ASAP and not later than the end of January 1996. The report should reflect that most of the work during 1995 was to define and develop the Demo; however, this effort is largely applicable to the commercial plant as well. Thus the writing should be descriptive of the general concept if possible.

Results from the LAR Conference - Steve Jardin briefly discussed his presentation at the recent Low Aspect Ratio (LAR) conference and his interaction with the LAR proponents. His Starlite talk sparked a great deal of comparison with a seemingly more attractive reactor design presented by Ron Stanbaugh of GA. Wong had also summarized the designs in his minutes of the meeting. The GA physics results indicated higher beta and higher bootstrap current with no edge current required. Hence, this reflected a much lower level of recirculating power and a much smaller reactor (one half the size of our designs). S. Jardin offered to work with GA on reconciling the physics differences. Steve mentioned that, in a follow-up conversation with GA, they agreed the design point can be unstable based on different code calculations. PPPL and GA are working to resolve the differences. Steve report good collaboration effort from GA. GA is also reporting optimum designs at aspect ratios around 1.4 whereas our investigations have been at A=1.25. S. Jardin agreed to investigate both larger (A=1.4) and smaller (A=1.1) aspect ratios in the search for stable and better performing plasmas. This would substantiate our findings over a larger parameter space. Steve also noted that PPPL had found a stable case at A=1.25, beta of 27%, and a 99% bootstrap fraction as compared to the previous 1.25/40%/85% case. It was felt that the end result may not be much different due to the tradeoff in current drive and beta.

Physics Conference Call - S. Jardin reviewed the results reported from the 28 November Physics conference call. T.K. Mau is taking the lead on the figure of merit documentation. If you need to review the draft, contact T.K. There is an issue related to the efficiency formulas used in LAR CD calculations. These formulas need to be checked for their validity for aspect ratios approaching unity, which is the case for off-axis current drive. The trapped particle corrections for LAR CD efficiency are also being checked.

C. Bathke developed, for D-K Sze, an LAR parametric analysis over a range of recirculating power. The power balance was altered by varying gamma and the current drive power. The results are posted on the WWW home page. Previous code results are also available for both shielded and unshielded center post concepts.

Ron Miller and Chuck Bathke installed a revised subroutine on RAMI, based upon algorithms developed during the PULSAR study. Also, the year of the estimate was updated to 1995$.

LAR Engineering - M. Tillack affirmed that he needs all LAR engineering write-ups by 8 December so he can meet his deadlines. Some analyses and trade studies are being done outside the systems code to determine the effects of changes in the configuration, e.g. size of center post. Favorable results from higher aspect ratio configurations may ease engineering difficulties. The divertor remains a problem area. Major issue areas include: shielded/unshielded centerpost, optimum plasma size/shape (BS, beta), current drive interface with plasma, and method to reduce TF resistive losses.

R. Miller reported that the (previously discussed) GA LAR design uses the centerpost as a limiter that intersects the plasma. C. Wong will try to determine the engineering parameters (heat flux, erosion, surface coating) that GA assumed for this limiter concept. C. Wong is working with Oak Ridge and Culham to obtain consensus on centerpost resistivity changes and transmutation effects.

D-K Sze summarized his conversations with C. Kessel regarding the conductive shell. The kink stability shell should be at a radius 1.3 times the minor radius, on the outboard blanket area for an area 60 above and below the midplane. The vertical stability shell should be at the same location but the shell should be both on the inboard and outboard regions for 75 above and below the midplane. An active coil should be roughly in the same area, but this would be very difficult to accomplish (ARIES II/IV had the coil behind the shield). S. Jardin suggested that the coil could be located beyond the shield but power would go up and time constants would increase. D-K should provide a specific vanadium design, with dimensions, to C. Kessel to evaluate the effective first wall and blanket resistivity and the capability of the basic blanket configuration to serve as the conductive shells for the kink and vertical stability. This would enable a decision as to adding shells and coils for plasma stability.

D-K Sze and X. Wang defined plumbing sizes for the blanket and divertor, respectively. The divertor plumbing sizes were deliberately oversized to assure allocation of adequate space. The routing scheme and heat removal surfaces are to be defined and transmitted to D. Lee on or about 15 December.

R. Miller noted that the initial results from the systems code with the new RAMI algorithms indicated an increased preference for close-fitting TF coils. This will put more emphasis on developing a credible maintenance scheme and access areas for plumbing, etc.

C. Bathke will incorporate the new TF cap structure thicknesses and the requirements for the PF coils into the system code inputs and generate a new reverse shear plasma envelope and first wall surface for an aspect ratio = 4. These data will be provided to D. Lee for configuration modeling by 6 December. [Due to unforeseen circumstances, these data will be delayed until after 12 December.]

Safety and Licensing - D. Steiner mentioned that most of the time had been spend finalizing resources to conduct a Hazard Analysis relative to the Protective Action Guideline (PAG). A graduate student, Bob Thayer from RPI, would like to perform his safety analysis at INEL. Fred Silady of GA will also represent the safety effort at GA continuing earlier done by Tom Dunn, et al.