Starlite Conference Call Minutes

10 January 1996

Participants: Wong, Bathke, Waganer, Lee, Steiner, Miller, Mau, Tillack, El-Guebaly, Sviatoslavsky, Siegfried Malang

Administrative

- The 29 November 1995 Starlite Conference Call 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 project Physics Group had a conference call on 4 January and a few important results are noted in these minutes.
- The dates of the next Starlite project meeting are 31 January-2 February (until noon) at San Diego. Details of the meeting agenda are discussed below.
- There has been no feedback regarding the project letter sent to Anne Davies summarizing the progress of the project and possible future work emphasis.
- TK Mau's phone number has changed from 619-534-9711to 619-534-2880.

PROJECT ACTIVITIES & RECOMMENDED PROJECT PRESENTATIONS

The agenda for the project conference call was to first discuss the topics to be presented at the upcoming project meeting, concluding with an approved list of topics. Then the status of each area would be reviewed. But it turned out that the appropriateness of being an agenda item and its current status were discussed simultaneously. So it will be reported in that manner.

LAR Workshop and Technical Data Interchange [31 Jan] - R. Miller informed the group of his efforts to solicit a balanced presentation on the Low Aspect Ratio (LAR) device. He needs to further confer with Ron Blanken, DOE, as to his participation. Martin Peng, ORNL, has offered to be a presenter and participant. Representatives (who?) from GA will participate as well as John Perkins from LLNL. At present, Ron Miller has more presentation time requested from our team and less from visitors. The team suggested a balanced presentation with time set aside for general discussion and planning. It was also recommended that following Ron's introduction, the visitors begin the presentation. R. Miller should also stress that the Starlite group will now be concentrating on the Reverse Shear design and the LAR is delayed until a future date. R. Miller will distribute a tentative LAR workshop agenda for comment this week.

C. Bathke commented that PPPL has defined four new stable equilibria cases. These LAR cases represent little or no edge current drive with lower beta values. C. Bathke has generated the EQDSK files that were sent to Mau to perform CD power assessments. [Here is the proper order of actions:
- Jon Menard, of PPPL, generates the stable equilibria and transmit them to Bathke,
- Bathke generates the eqdsk files appropriate for Mau's current-drive analysis,
- Mau, using CURRAY; determines the current-drive efficiencies, as measured by gamma_B, and transmits the results back to Bathke,
- Bathke completes the systems analyses (e.g., optimize over temperature, etc.) and issues the strawmen.]

It is recognized that these cases may not have consistent triangularity solutions and may not represent valid engineering configurations. A case in point was the need to have the center post serve as a limiter intersecting some of the plasma flux lines (ref. Kessel suggestion). Even with these engineering and physics inconsistencies, the team would like to have strawmen for these cases developed and presented at the LAR workshop.

Main Project Meeting Concentrating on Reverse Shear Concept Definition [1-2 Feb] - The main project meeting will commence with F. Najmabadi reviewing the general project direction. Topics would include the IDEAS charter, the Starlite Mission Statement, and recommended project milestones with dates. Feedback from DOE and the FEAC meeting will be reviewed, if available.

The physics results to be presented at the meeting were discussed at the physics conference call. One of the planned physics talks during the project meeting will be "Comparison between second stability and RS power plants based on latest physics assumptions and models" by Dave Ehst. C. Kessel will present the need for and the resulting engineering requirements for kink and vertical stability systems. [T.K. later noted that more phyiscs talkes will be forethcoming. ] [The engineering solutions will be discussed in the Engineering talks.]

Per the last CC, C. Bathke generated a new RS strawman which incorporated a new representation for the TF structural cap (per L. Bromberg) and the central solenoid coil stack. These data are being used by D. Lee and C. Wong to define the chamber configuration. Upon examination of the data, C. Wong felt the envelope for the divertor slot was not wide enough and worked with C. Bathke to develop a new algorithm to refine the slot to meet the local physics requirements. Meanwhile, L. El-Guebaly felt that any increase in divertor slot width would adversely impact the blanket coverage and the overall tritium breeding ratio. It was decided that C. Bathke should develop a new strawman geometry and forward that to D. Lee, C. Wong, and L. El-Guebaly to determine the relative impact (due Friday, 12 Jan). If conflicts arise after the new geometry is evaluated, a mini-conference call will be held, say early next week.

The term "divertor cassette" implies that the divertor would be removable without disturbing either the inboard or outboard blankets and shields. But it was decided at the last conference call and confirmed today, that such a configuration would not be possible. At present, the project is assuming that the divertor would be replaced at the same frequency as the blanket. Thus, it can be removed and replaced with the outboard blanket and shield modules. After removal from the power core, the divertor module may be removed from the blanket, hence it may be considered as a cassette in that sense. Clement and Dennis will work closely to obtain the desired functionality while Laila will be involved to assure proper shielding and breeding. It was noted that the geometry in the divertor slot is three-dimensional to accommodate the plumbing so some additional shielding/breeding may be provided in local areas.

D. Lee is inputting C. Bathke's strawman for the aspect ratio of 4 to define the power core configuration. He has input the data for the PF coils and the TF outlines. He is currently working on VV, shielding, and first walls. He still needs to obtain the toroidal thickness of the TF coils from X. Wang or C. Bathke. C. Bathke noted for Dennis the geometries likely to change if the divertor slot is changed. C. Bathke mentioned that, per L. Bromberg, the thickness of the TF structural cap is equal to the bucking cylinder and extends down to near the maintenance opening. [Action: L. Bromberg should define the outboard limit of the cap structure.] Also the coil dimensions do not include thicknesses for the cryogenic dewars. An additional 10 cm should be added for dewar thickness. Dennis will include a preliminary configuration for the dewar based upon the prior definition (ala ARIES II-IV). Then the pros and cons of the dewar configuration can be discussed at the meeting.

In addition to the earlier divertor work, C. Wong noted that X. Wang has defined a preliminary sizing layout for the divertor piping. D-K Sze is supporting this with thermodynamic analysis of the divertor system. Ali Mahdavi is working on ways to increase the core radiation (and reduce the heat load on the divertor). Approaches include reducing the He and O concentration and adding other elements such as Argon in the plasma edge region. Clement is also working with Dai-Kai to quantify the divertor vacuum pumping requirements.

Leslie Bromberg will present the recommended coil structural design approach, geometry constraints, and limiting structure and coil stresses. These should be consistent with the Bathke strawmen and in the configuration being developed by D. Lee.

Igor Sviatoslavsky will prepare a presentation of the design approach for the toroidally continuous, conducting shells for vertical and kink stability (and coil for vertical stability) and the technique to structurally mount the inboard and outboard blanket and shield modules, not using the vacuum vessel as the primary structure. He and Dennis Lee will coordinate their design approaches. Chuck Bathke asked if it were still necessary to maintain an allowance of 20-30 cm for the vacuum vessel and Igor verified that indeed 20-30 cm would be necessary even if the vacuum vessel were not the primary structural member.

L. El-Guebaly will present her new work on shielding, et al., with the new vacuum vessel design approach. She is using the new FENDL cross-section data library. Also she will assess the effect of the new stability shells and coils on the tritium breeding ratio. Laila, Dai-Kai, and Chuck Kessel will confer on the suitability of the existing materials to provide the required conductivity at the proper radial location.

Laila will work with Jake Blanchard to obtain a summary viewgraph explaining the use of the available EM codes to be employed to analyze the Starfire first wall and blanket modules. Jake should also explain the method used to determine or estimate the driving currents (and current paths).

It was recommended that Dai-Kai Sze summarize the progress on incorporating the requirements for a conducting kink stability shell and an active vertical stability coil into the blanket. Data would include the required conductance and the capabilities of the available materials.

Ron Miller discussed the economic modeling topics to be included, such as groundrules, comparisons and benchmarking of the code with economic analyses from other alternate concepts.

D. Steiner is planning to summarize the Safety and Licensing plans for the new quarter. A graduate student, Bob Thayer from RPI, is beginning to work with INEL on the safety analysis. Fred Silady of GA will also contribute to the safety effort at GA, building upon earlier work done by Tom Dunn, et al.

T.K Mau suggested a seminar to cover the subject: Implementation of a Neural Network Disruption Alarm on the DIII-D Tokamak by D. Wroblewski and G. Johns (ORINCON Corp) and Jim Leuer (GA). Given the full day devoted to the LAR workshop and a full agenda for the RS tokamak concept, it was uncertain that sufficient time would be available for the seminar which would likely require an hour or more. L. Waganer will assemble the preliminary agenda and see if enough time might be available. If not, the seminar could be held early Friday afternoon.

The question was raised as to the extent of coverage for Starlite at the upcoming ANS meeting. Mark has been approached to lead a Starlite session if sufficient papers were forthcoming. But only four papers were identified, of which most were already associated with an existing session. But there was a team consensus that it would be beneficial to have a strong presence at the meeting, perhaps a plenary paper addressing the status of Starlite. Don Steiner and Farrokh would discuss this approach prior to a Thursday ANS planning conference call attended by Igor Sviatoslavsky.

The group felt another conference call was warranted before the project meeting, with 24 Jan being selected. L. Waganer will issue a draft agenda this week for review and comment.