Starlite Conference Call Minutes

22 May 1996

Participants: Sze, Billone, Ehst, Wong, Bathke, Waganer, Cole, Bromberg, Hofer, Steiner, Mau, Miller, Najmabadi, Tillack, Malang, El-Guebaly, Sviatoslavsky, Blanchard

Administrative

Safety and Licensing

Per Don Steiner, B. Thayer is proceeding with the preliminary safety analysis for our current design. He has been working on the effects of the time history for a LOCA (preliminary data presented last meeting.) Igor Sviatoslavsky told the group of the updated results, which indicated a maximum first wall temperature (inboard, midplane) to be 1060_C. Bob is needing material inventories as a function of position, and Laila said she would contact H. Khater to provide the data to Don Steiner. Don reemphasized that the data for the preliminary safety analysis would be available at the next meeting.

Physics

T.K. Mau conferred with C. Kessel who has used TSC to simulate the ITER RS startup scenario. The ITER approach uses the PFC flux to initially ramp up the current. Then the Lower Hybrid system can take over to complete the current generation. Due to other commitments, Chuck does not have time to do the analysis in time for the next ARIES-RS meeting. Dai-Kai brought up that the issue of divertor operation during startup should be considered.

T.K. has also been revising the RF system parameters based on the new strawman. The ICRF power level has increased from 40 MW to 50 MW, but he had enough design margin to absorb the power increase without increasing the size of the waveguides. On the lower hybrid system, there are two leading design approaches offered by the Japanese and the EU ITER design teams. These are the multijunction and the hyperguide respectively. One of the main distinctions is the technique for cooling the waveguides. There are also some differences in power handling and directivity of the antenna. T.K. is continuing to evaluate these options and will make a decision by the meeting date. TK is still waiting for tungsten irradiated conductivity data from Mike Billone - Dai-Kai will follow up on this request.

Recently at PPPL, D. Ehst spoke to Dr. Braams about the radiation in the scrapeoff layer. Dr. Braams thinks that the radiation fraction in the SOL will not be large. There is also a concern that ITER is to operate at a "Greenwald factor" of 1.5; whereas ARIES-RS would be at a factor of 2.0. Farrokh Najmabadi noted that this factor is important for ohmically-driven machines but not so much for a steady-state machine. Tom Petrie continues to evaluate and assess this topic.

TK also sent C. Bathke an algorithm for CD efficiency scaling as a function of Zeff, ala 1.7 = nominal, 1.9 = 10% less than nominal, and 2.1 = 20% less than nominal.

System Studies

C. Bathke posted the results of the latest ARIES-RS strawman on his Web page, followed with a slight correction on component masses. Laila El-Guebaly has contributed some comments. Chuck also noted that he intended to investigate the effect of the ion temperature (these results were posted on 5/23.) Laila and Ron Miller have been analyzing the effects of the longer component and amortization life on the plant economics.

Engineering

Jake Blanchard reported that his group had finished the electromagnetic disruption analysis and the results had been distributed for review. The disruption time had a weak influence on the induced loads. Jake is now comparing his results to the ITER analyses and results. Jake is concerned about the level of the load in the outer stabilizing shell. The modeling of the segmented divertor was discussed, mainly how to estimate the conductivity across the many interfaces in the toroidal direction. ITER has taken a percentage of the theoretical conductivity for their analysis. However, there are also local eddy currents to be considered. Jake was asked if his group could do a 3-D analysis for ARIES-RS. He thought they could do a simple, limited-effort 3-D analysis by the end of the summer. Igor Sviatoslavsky and Siegfried Malang are cooperating with Jake on the interactive definition of the divertor structural requirements and the configuration. Clement Wong noted that current stresses are in the 200 MPa range and care must be taken to retain an adequate design margin.

TK Mau covered most of the engineering aspects of the RF systems in the Physics section reported above. The ICRF power has increased, but the current size of the wave-guide launchers should be adequate. Dennis Lee had modeled one of the three waveguide launchers to help Laila estimate adequate local shielding. TK is in the process of defining the other two RF systems. [TK, if you can get this definition to Dick Cole somewhat before the meeting, perhaps he can include it in his modeling.]

Leslie Bromberg continues to work on the analysis and the solutions for the out-of-plane loads on the TF coils. He also faxed out his TF coil design to selected individuals.

Clement Wong noted that Tom Petrie continues to work with F. Najmabadi on the divertor physics, trying to integrate the amount of radiation from the main mantle, scrape off region, and the divertor region. They are also working with the radiating impurity species and Zeff level. Elmer Reis and Xueren Wang are working on the capability of the divertor to handle the 5 MW/m2 maximum heat load. They are adjusting the thickness of the back wall of the divertor cooling panel to handle the heat load and keep the total thermal stresses within design limits. This is being done with Igor and Siegfried who are working the structural aspects of the divertor. Xueren is preparing detailed CAD drawings of the divertor components. Clement mentioned that some extrapolated DIMES and sputtering data indicated a possible high level of tungsten erosion which might be anticipated in the divertor slots.

Dai-Kai Sze reported sending out a memo detailing his thermal-hydraulics analysis of the blanket. His analysis decoupled the heat transfer effects and the MHD effects. With the velocity profile assumed, his analysis indicted the 1 MW/m2 surface heating and the nominal nuclear heating could be accommodated.

Laila El-Guebaly mentioned she is dividing the blanket into regions based upon multiples of the lifetime and the maintenance scheme to help maximize the components useful lifetime in the reactor, reduce the replacement cost, and minimize the rad waste. She is also working on the divertor shielding using the evolving divertor design. There was some confusion during the CC as to the thickness of the cryostat and the vacuum vessel. According to the Design Data Book, the VV has two 3-cm thick face plates and the cryostat has two 2-cm face plates.

Dick Cole has assumed the configuration development role from Dennis Lee. Dick is translating the latest strawman surfaces onto the previous design to refine the modeling. Dennis is available via phone to help smooth out the transition.