Starlite Engineering Group Conference Call

18 October 1995

A Starlite Engineering group conference call was held on Wednesday October 18 using the MDAC call-in phone number (314-232-7776) at 10:30 PDT (11:30 MDT, 12:30 CDT, 13:30 EDT). NOTE: this is the new time, which was changed following the last full project conference call (Sept. 27).

Chuck Bathke, Mike Billone, Leslie Bromberg, Laila El-Guebaly, Dennis Lee, Ron Miller, Farrokh Najmabadi, Igor Sviatoslavsky, Dai Kai Sze, Mark Tillack, Les Waganer, Clement Wong,

note: action items are in bold-face.

The next call for the Engineering group was not formally scheduled (but it should take place Nov. 8 according to the general conference call schedule).

1. Plans for the October Project meeting

The agenda for the upcoming full project meeting (Oct. 25-27) was discussed. The agenda was divided into several sessions: Design review, special issues, combined project status reports, and design integration subgroup meeting. The agenda will be modified based on the discussions and sent out to the group as soon as possible. M. Tllack will contact Steve Jardin immediately to coordinate the schedule with the Physics group.

It is important to make decisions on the overall fusion power core configuration in order to move forward with the design of individual components. The presentations should provide adequate detail to identify the major interface requirements and to provide the necessary inputs for the system code. A new strawman will be released following the project meeting.

The special issues include modeling of disruptions and their effects, MHD heat transfer, and costing.

2. System code inputs and major device parameters

L. Guebaly has developed some initial parameters and e-mailed them out for review. They were also placed on the Starlite Web server. We still need to improve the listing of major device parameters. L. Waganer and M. Tillack are responsible for the Engineering Parameters list, as agreed at a previous project meeting.

The vacuum vessel was modified to include some safety factors (the thickness is 20 cm inboard and 30 cm outboard).

A question arose whether cooling is required for the VV. D.K. Sze indicated that if the VV is attached to the shield, then it probably wonÕt need coolant. Even if it is not attached, radiation may be enough to maintain acceptable temperatures.

Eventually, the thermal analysis of the shield must be documented.

F. Najmabadi said that we may need to bake the VV, in which case a small coolant system on the back side of the vessel could be added.

R. Miller is concerned that the VV is getting complicated and may have maintenance implications.

C. Bathke pointed out that the 10-cm increase in thickness appears to be taking very valuable real estate.

F. Najmabadi indicated that the extra thickness would come mainly out of the shield.

L. El-Guebaly identified a need to increase the thickness for safety factors.

F. Najmabadi said we would come back to this question and discuss it at the project meeting.

D. K. Sze suggested that the safety factors for a commercial power plant should be low because the database should have reduced uncertainties by then. C. Wong added that we must distinguish between types of safety factors that will reduce to to lower uncertainties and those which are unavoidable (such as factors for manufacturing tolerances).

L. El-Guebaly requested that the divertor cassette be specified. These drawings have been sent around recently. Apparently the FAX did not transmit properly. L. Waganer and C. Wong will send figures as needed to the team members.

M. Tillack asked whether the divertor configuration is even workable, given the very short slots for heat exhaust. C. Wong answered that probably it is, but the design is still evolving. F. Najmabadi pointed out that we should still keep all options open at this point in the study.

A question was raised over who would perform the thermal hydraulics for the divertor. M. Tillack suggested that T. Hua will do analysis and X. Wang will do the mechanical analysis. This was agreed.

L. El-Guebaly indicated that we need to upate the costing model and include replacement costs.

3. Status of maintenance approach assessment

M. Tillack asked if F. Najmabadi has provided his inputs regarding the configuration and maintenance approach. F. Najmabadi replied that he is currently working on a response. I. Sviatoslavsky is planning to present his most recent ideas next week, and hopes a top-level decision is not made prematurely. F. Najmabadi replied that the decision is still open for discussion. Additional time will be allocated during the project meeting.

I. Sviatoslavsky said that we need to know the loads. D. K. Sze offered that we must assume something for loads in order to go forward, and that more detailed calculations hopefully will follow. F. najmabadi and M. Tillack also suggested that we must make a quantitative guess to start and hope to analyze the actual structures later.

4. Key configuration issues

M. Tillack pointed out some of the important remaining configuration issues, such as the crown dimensions, pipe routing, and penetrations (CD/RF, divertor channels and pumping ducts).

L. El-Guebaly requested info from T.K. Mau on rf penetrations. there will be an opportunity for discussion during his scheduled talk at the project meeting. There is also a need for more info on the divertor pumping ducts.

D. K. Sze requested that we add a working group on piping and penetrations to the agenda. C. Wong agreed that we need to discuss this.

L. El-Guebaly added that we need info on the stabilizing shell. D. K. Sze said that C. Kessel will have something later. He was supposed to provide the information to the engineering group following his wedding.

R. Miller said that he thought it was agreed that the stabilizer could be placed behind the blanket. D. K. Sze responded that the location depends on the conductance requirement.

L. Bromberg reported that he is doing FEM analysis, to be presented at the meeting (related to the issue of the crown height). Currently there are no holes modeled in the crown. He will decide if they are needed.

F. Najmabadi suggested that we may be able to pump the VV and not directly on the divertor. In that case, we may be able to put all the pumps at the bottom. We need a neutral transport calculation to answer this question. Art Grossman could do this (even in 3D).

I. Sviatoslavsky said that we will still have a piping problem. D. K. Sze responded that it would not be so large. F. Najmabadi added that the problem is tractable if we leave adequate room between the VV and shield.

There was some discussion of the mechanism by which the Engineering GroupÕs inputs are being incorporated into the design. M. Tillack pointed out that L. El-Guebaly has the responsibility for interfacing with the system code. The design is still evolving. For the project meeting, the team should use the numbers from the 7/18/95 strawman. In general, a new strawman will be released midway between meetings. During that period, the previous strawman should be used for ÒreferenceÓ calculations until a new strawman is defined, taking into account the newest analyses.

For the system code inputs, C. bathke is relying on Miller for costing, Mau for curent drive, Kessel for beta and equilibrium inputs, and El-Guebaly for engineering.

5. Documentation of LAR assessment

M. Tillack indicated that we need to do something to document our work. D. K. Sze is concerned that we havenÕt expended enough effort and lack the expertise to make sound (defensible) conclusions. We would have to expend more resources. Our conclusions, such as they are, suggest that the LAR tokamak probably doesnÕt make sense for a power plant, but could make sense for a near-term device.

In that case, should we look at near term application? Also, the waste disposal concern is really driving the design through the impact on the inboard radial build. How can we resolve the waste disposal issue given the uncertainties. Will we be able to do the necessary work given the resources?

R. Miller suggested that we Òput it on the back burner.Ó But clearly some additional work is needed.

D. K. Sze indicated that we need a strong effort attempting to solve the problems, or our work will be perceived as biased.

C. Wong said he doesnÕt know how much effort that will require. However, it is our responsibility to document whatever we have.

C. Bathke agreed that it needs more work, and more optimization. F. Najmabadi asked to hear how much work is needed. We should not shy away from our conclusions. Simply document our assumptions clearly, and we will be justified in making whatever qualified conclusion result from those assumptions.