ARIES Documents -- Meetings ArchiveARIES Conference Call, 25 July 2012
Documented by L. Waganer
Les Waganer noted that the next meeting is scheduled for a full day on 26 September and a half a day on 27 September 2012 at Gaithersburg, probably at the Gaithersburg Hilton, pending arrangements. The next call will be on 24 July at the usual time with the normal phone number.
Les also reminded people that drafts of the 12 June CC minutes and the May 31-June 1 meeting minutes have been distributed for review.
ARIES Technical Efforts
Decay Heat Analyses - Laila El-Guebaly is completing her decay heat analyses as Paul Humrickhouse needs these results for his LOCA/LOFA analysis. She has been concentrating on the inboard and outboard radial builds. The outboard components exhibit higher decay heat due to the higher NWL and the presence of the tungsten stabilizing shells located between the blanket segments. Therefore, the inboard components will not radiate heat to the outboard or to the W-based divertor. Therefore the only means for the inboard Structural Ring and VV to dissipate their decay heats is through the inboard LT shield. She E-mailed the decay heat results to the ARIES team on July 3, 2012.
Divertor Fracture Analysis - Jake Blanchard has been working on the effect of both small and frequent ELMs (around 20 Hz) as well as the less frequent, but more powerful, large ELMs. He noted the base temperature assumed is 1500°C (temperature between pulses). Mark Tillack thought that the temperature obtained from thermodynamic analyses would be an average temperature including the power in the ELMs. This definition needs to be better defined. The critical determination is: will the ELM pulses melt the tungsten surface layer and does it have time to re-solidify before the next pulse. The footprint of the larger ELMs may spread out the power by a factor of four, which might be sufficient to prevent damage.
Mark thought this was a good analysis to scope out the problem of the ELMs.
Chuck Kessel thought on a single shot, the baseline temperature should be lower than 1500°C, perhaps 1000°C to 1200°C with the heat loading of 5.5 MW between ELMs and 7.5 MW average including all the ELM discharges.
Mark thought thinning the tungsten armor might lessen the thermal increase of the divertor structure
Tom Rognlien said that he and Marv might contribute to the erosion analysis of the divertor plates using the sputtering analysis capability of UEDGE, but it would be a big task. ITER's analysis would be helpful as a benchmark case. Chuck Kessel said he would also try to estimate the mass loss of the divertor due to the ELM discharges.
Systems Code Results - Mark Tillack reported the systems code is almost ready to run with new algorithms and inputs for the ACT-1 TOFE data sets. Specific changes are:
Kessel noted we need to obtain the COE for many design points to select the attractive operating design space. We also need to resolve the outboard heat flux.
CAD Updates in the ACT Designs - Xueren Wang has been concentrating on the divertor region definition with the inboard blanket, the bucking cylinder and the manifolding changes. He is working with Siegfried Malang on the maintenance design options.
Scrape-off Layer Modeling in the Divertor Region - Tom Rognlien said they are now evaluating the 40 cm-long divertor plate lengths. He is also doing analyses with a 2X narrower SOL. Depending on the results, he may try narrowing the SOL by another factor of two.
Tom also mentioned that the helium pumping capability may be changing. He will try to correlate with the ITER helium pumping calculations, especially under the divertor dome.
Marv Rensink said they did a reference case with the IB divertor leg, located 40 cm radially from X-point. They also shortened the outboard leg to both 1 meter and 1/2 meter and found stable solutions for both cases, but with a higher heat flux on the shorter one.
Safety Analysis - Paul Humrickhouse has been conferring with Laila El-Guebaly regarding the expected decay heats for the contemplated materials. He has incorporated the latest radial builds from Laila, TF coil data and the new bucking cylinder geometry.
Plasma Steady State Solutions - Alan Turnbull has been working with his plasma modeling code, but at present, he does not have an update.
Vacuum Vessel Design Code Guidance - Tom Weaver said he has found specialists within Boeing that have experience with the design codes for pressure and vacuum vessels. He will distribute this information to the team shortly.
FESAC News - Dale Meade mentioned that a FESAC panel has a charge to "Assess the US fusion (non-ITER) program priorities" assuming a near term level budget and continuing funding for ITER. A second option would have increased funding for non-ITER projects. It is to be assumed that the material sciences would have a high priority. The report is due in September 2012.