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ARIES Documents -- Meetings Archive

ARIES Conference Call, 16 August 2005

Documented by L. Waganer


Participants:
(ANL) -
(Boeing) Waganer
(DOE) -
(FPA) -
(FZK) -
(GA) Turnbull
(GT) Abdel-Khalik
(INL) Merrill
(MIT) Bromberg
(NYU) Garabedian
(ORNL) Lyon
(PPPL) Ku
(RPI) -
(UCSD) Mau, Malang, Raffray, Wang
(UW) El-Gububaly

Administrative

The review meeting with the stellarator community will be held at PPPL on Thursday, 15 September. The regular ARIES meeting will commence after the review concludes mid afternoon. The ARIES meeting will continue the morning of Friday, 16 September. A preliminary agenda has been distributed to the team and to the community invitees. We need to provide and post the presentation material somewhat before the meeting so people not attending might have a chance to view the materials. Alan Turnbull confirmed he will make a presentation on the Beta assumptions and impact assessment. Jim Lyon said he and Long Poe Ku have invited papers at an upcoming international stellarator workshop, thus they can have additional interaction with the stellarator community. Mike Zarnstorff has been appointed at the PPPL point of contact for the ARIES program.

Compact Stellarator Reactor Engineering Assessment

Coil Design And Analysis - Leslie Bromberg said he would attend the PPPL meeting and is working to obtain a credible coil design approach that could be integrated into the present power core approach. His fall-back approach is to use NbTi superconductors cooled to 1.8K. This would require additional shielding that would increase the radial build, so this approach would have negative consequences on the feasibility of this power plant. Leslie agreed to talk to Jim, Rene, and Laila to discuss alternative approaches. Rene needs some design input early in the week before the meeting to prepare his slides.

Blanket and Shield Neutronic Analysis - Laila El-Guebaly noted Siegfried Malang devised a clever design approach to address the neutron streaming through the helium cooling tubes. This may enable the manifold to be reweldable. However, there is still too much streaming of neutrons to the vacuum vessel and magnet. Siegfried said there may be some local shielding solutions per Lailaís suggestion at the June ARIES meeting. This would involve adding small shielding enhancements attached to either the backside of the manifold or vacuum vessel.

Blanket Design - Siegfried Malang continues to work on the field period maintained blanket design approach with the main goals of reducing the radial build and the radwaste stream volume. For strength reasons and to allow for coolant manifolding, the breeding zone and the HT shield should be combined. Two possibilities are:

  1. Combine them permanently into one component. However as Laila pointed out, this would significantly increase of the waste volume to be disposed of with each blanket replacement, occurring approximately every 6 years.
  2. Combine the high temperature shield and the manifold region into a lifetime component, (similar to the modular maintenance design approach) and exchange the breeding modules after the replacement unit has removed from the torus. This does have a consequence of slightly increasing the radial build.

Laila mentioned that "approach b" may be a better solution as it minimizes the radwaste stream.

Coil Structural Analysis - Xueren Wang and Carl Martin is continuing to analyze the coil structures and the magnetic forces. They have made some progress and will report his results and status at the PPPL meeting.

Liquid-Cooled Divertor Experimental Results - Said Abdel-Khalik reported that the results from the liquid-cooled experiments very closely confirmed the analytical results previously provided

Compact Stellarator Reactor Physics Basis

Physics Assessment of New QAS and QH configurations - Long Poe working to improve the alpha-confinement for the NCSX cases. He is also investigating the bias on the magnetic spectrum. He believes he can find improved cases to present at the PPPL meeting.

Beta Limit Assessments - Alan Turnbull said that he would be preparing a presentation for the PPPL meeting that presents our understanding of credible Beta limits for the Compact Stellarator.

Divertor Heat and Particle Load Modeling - T.K. Mau continues to work with Hayden McGuiness on the divertor definition. He is working on the location and surface topology of the divertor plates and trying to define the magnitude and the variation of the heat load. He is reporting that the peaking factor to date is in a range of 20 where a peak load around 10 MW/m2 may be achievable. The plates are not conformal to the Last Closed Magnetic Surface (LCMS). Tentatively, 90% of the field lines intercept the divertor surface. He is working to assess the alpha particle heat load on the first wall.

Compact Stellarator Integrated Systems Assessment

Systems Code Analysis - Jim Lyon noted he has achieved some success in obtaining convergence for his system code runs. His independent parameters are coil-plasma separation distance, aspect ratio, and beta. The previous lack of convergence problem was related to magnet field strength being out of scope that results in out-of-bound and non-physical solutions. Having fixed that, some of Kuís cases are quite robust. The other 225 NCSX cases still have some problems converging. He is generating data for his September presentation.