30 June 2012 Author: Lester M. Waganer, firstname.lastname@example.org-->
ARIES Documents -- Meetings ArchiveARIES Conference Call, 12 June 2012
Documented by L. Waganer
Les Waganer reminded the team that he had just distributed the action item list for the May 31-June 1 2012 ARIES meeting. If any omissions or changes are needed, please send them to Les.
Les Waganer noted that the next ARIES meeting will likely be held in the Washington, D.C. area in the late September time frame. The team was polled for major date conflicts, including the TOFE meeting in late August. Farrokh Najmabadi and Mark Tillack will decide on the best week in September for the meeting. [Later, Farrokh and Mark agreed on the week of September 24-28 for the meeting. Les Waganer created a Doodle scheduling choice on that week to select the better dates for the meeting. The final meeting dates were decided to be Sept 26 (Wednesday) and half a day on Sept 27 (Thursday).]
Farrokh Najmabadi suggested that we needed to hold a project conference call soon. It was decided the next conference call would be on July 3rd, at the normal time.
General Fusion Information
Dale Meade reported that he had just attended the American Security Project event called "Magnetic Fusion Energy - Steps to Commercialization". It was held in the Washington, D.C. area to help promote and advance MFE commercialization. This is a link to the web site Dale mentioned. In addition to Dale, several other MFE leaders were in attendance. Farrokh Najmabadi and Tom Weaver were contacted to attend, but were unable to do so.
Dale related that he has been asked by the G7, a group of DOE national lab leaders, to coordinate the preparation of a MFE development plan leading to the U.S. Demo. It would include identifying the major research and development needs to advance fusion to the next step and beyond.
ARIES Technical Efforts
Reliability Modeling of the Divertor Components - Tom Weaver mentioned that Dan Driemeyer will soon be involved in the assessment and modeling of the hot blanket and divertor structures.
Tom told the team that I-Li Lu is making progress on the reliability modeling of the baseline divertor modules.
Tom has contacted several experts in Boeing that may have knowledge of vacuum and pressure design codes. Tom will continue to seek this design code information. Paul Humrickhouse offered to solicit vacuum vessel code information from Lee Cadwallader.
Core Plasma Physics for Steady State Solutions - Alan said he had been on vacation, but Holger St. John has been updating the plasma codes for the next stage of analysis.
Power Core Safety Analysis - Paul Humrickhouse told the group that he has been refining the MELCOR code and inputs to include the suggestions offered at the last meeting, including the LOFA and LOCA conditions. Paul still needs data on the material properties for the LT shield - it was suggested Paul should use the properties of F82H as it has similar properties to the LT shield structural material. Paul asked about the seismic loading conditions and the general consensus was that isolation absorbers could be used to mitigate the seismic inputs. Also the LT shield is only lightly loaded, primarily by gravity loads.
Material Information - Arthur Rowcliffe said he had just visited ORNL and spoke with several material experts in the field of martensitic and ODS steels and tungsten. He intends to make sure these experts are aware of our materials needs and the range of properties the team desires. He will convey any new information he gathers.
Plasma Edge Modeling in the Divertor Region - Tom Rognlien said that he has made a few modeling runs of the plasma edge physics model with argon gas as opposed to the previous neon gas. He achieves about 25% more radiated power for the attached plasma cases with argon than for neon when limiting Zeff to 2 for each, which for argon corresponds to a concentration of 0.31%, whereas for neon it corresponded to 1.0% owing to the difference in the square of the nuclear charge.
For the hydrogen/neon solution for the detached divertor plasma case, he calculated the spatial variation of the helium concentration using the multi-charge-state model that includes drag on the hydrogen flow and the thermal force effect along the magnetic field. The ratio of the helium concentration at the private-flux boundary adjacent to the pump region to the concentration at the core boundary is ~0.05 compared to the published ITER value of 0.2, which is likely because of the strong He-repelling thermal force in the ionization front associated with the fully detached solution. Implications should be discussed.
Marv Rensink mentioned he has been doing successful detached plasma runs with the shorter divertor plate length on the inboard area (per the suggestion in the May-June meeting). Mark Tillack thought those results were worthwhile, but the divertor geometry may be more restrictive than discussed in the previous meeting, thus further reducing the inboard divertor length. When the new strawman radial builds are released, they may require a larger major plasma radius, thus increasing the divertor region and the inboard divertor length. Mark also said that the outboard divertor legs may also be impacted similarly. The new physics runs and the divertor geometry will be used in new systems code runs to determine the next strawman.
Power Core Physics Modeling and Modeling for System Code Database - Chuck Kessel said he is doing additional time-dependent TSC simulations of ACT-1 with varying temperature and density profiles including internal transport barrier profiles, which can be compared with the Multi-Mode transport model being done at GA. He has tested the use of neon as the intentional impurity in the core plasma simulations and found about 0.85% is required to reproduce the previous results, which used 0.3% argon as the impurity. Efforts to provide a disruption simulation are continuing.
He said that the calculation for the peak heat flux on the divertor in the systems code may not apply to the detached plasma regimes we are seeing in the detailed edge plasma modeling from LLNL; however we do not have a model to predict the detached peak heat flux. According to results from LLNL at the last meeting, the heat flux on the divertor target plate is strongly related to the location of the target plate from the X-point and relative to the radiation front. For the "short" divertor length the heat flux does look like a standard heat flux profile on the target.
Chuck is recommending using a single spectrum lower hybrid (LH) with a single launcher/antenna. In previous designs, the LH system used several LH frequencies with multiple launchers/antennae. The single spectrum should be much simpler to implement.
Systems Code Results - Mark Tillack has been running the systems code with the currently available physics and engineering points with the near term goal of reducing the data set with a smaller range of net power around 1000 MWe. This would produce the desired results much faster. Chuck Kessel said his updated data set will be available shortly.
Power Core Design - Xueren Wang is refining his CAD model in preparation for the new ACT strawman.
Xueren is surveying the available coolant turbulence models for the revised thermal and stress analysis. Mark and Farrokh will recommend the proper model for Xueren to use. Mark asked Chuck Kessel if the quoted heat load represents the time-averaged heat loads (including the peak ELM loadings as well as the lower values between ELMS) or is it the baseline heat loads between ELM pulses (no ELM heat loads included). It was concluded that the quoted net loads would be the time-averaged heat loads (including the peak ELM loadings as well as the lower values between ELMS).
Divertor Structural Analysis - Jake Blanchard has completed preliminary thermal analysis of the ELM heat loads on the tungsten divertor surfaces and concluded the ELM loads would melt the surface layer. In the near-future, Blanchard will refine the analysis to predict the thickness of the melt-layer. Mark Tillack and Chuck Kessel discussed some considerations relative to the appropriate peak heat load to be used for the analysis. They will discuss this further to produce a final recommendation.