ARIES Documents -- Meetings ArchiveARIES E Meeting, 7 October 1999
Documented by L. Waganer
Bill Dove informed the call participants of the recent DOE budget increase. This increase will enable the Advanced Design Study group to examine in more detail both MFE and IFE conceptual design approaches. The budget level is nominally around $3M, less some "set-asides", funding for smaller programs, and general "taxes". The ARIES team should examine and propose areas where more or new work is needed for MFE and IFE. This new work could be within the ARIES framework and also within separate studies proposed by organizations. Charlie Baker said the new initiative proposals could be submitted by several types of organizations and should not be constrained within specific technologies. The peer review and selection process is to be determined.
Farrokh Najmabadi noted that this increased level of funding would enable the ARIES-AT study to be completed next year with our normal level of assessment detail. It is anticipated that ARIES-AT will be considered by the technical community as the next baseline MFE commercial fusion power plant, thus our analysis and design work must be of high quality. The recommended follow-on effort for the neutron source study is to be determined. Some level of IFE design concept definition and evaluation will be accomplished, mostly in the chamber design area.
Bill Dove and Farrokh Najmabadi met with LLNL and LBL IFE representatives to discuss the involvement of the ARIES design team. Both groups welcomed and fully supported an ARIES investigation of IFE. LLNL was quite anxious to work with ARIES. LBL feels their Number One priority is the heavy ion driver upgrade; they are less anxious to take on the extra burden of working on a conceptual design project.
Mark Tillack was "volunteered", in his absence, to establish an IFE page to links to IFE organizations, data sources, and planning documents.
The dates for the next meeting were affirmed as 1 December, starting at noon, through 3 December, ending at noon. The next ARIES conference call will be 4 November 1999 from 9 a.m. to 12 noon PST. The call-in number is 314-232-3598. Farrokh Najmabadi reported that most of the ARIES-ST FED papers have been edited, formatted, and sent out for review.
Neutron Source Study
Don Steiner noted that the neutron source study was behind schedule, with most people hampered by the effort to support the Snowmass conference.
Ron Miller reported that he had published a plutonium-burning neutron source plant strawman generally based on the ARIES-ST physics and engineering design approaches. The intent is to retain a net power of 1000 MWe with a smaller plasma and a higher neutron multiplication value. The strawman (see Case L at http://aries.ucsd.edu/~miller/index2.html) had a Q=3 with a 1-meter plasma radius. Ron was using a lean mixture of T and the plasma was largely D-D. Don Steiner was concerned that the code was properly accounting for the power balance with such a plasma mixture and small size. There was also concern that this machine was being assessed in the code as a commercial machine (10th of a kind), yet the need is for a near-term device and it will be compared to other near term devices, e.g. ATW. The physics should not be considered as near-term either.
Power Cycle Modeling and Cost Validation
Les Waganer discussed the changes in the basic ARIES-AT power cycle to accommodate the large fusion co-generation power plant. The approach is to add a heat exchanger downstream of the helium turbine. The extracted power for the hydrogen electrolyzer reduces the power available at the recuperator, which in turn lowers the input coolant into the divertor and blanket. The effect is to slightly lower the overall (electrical) cycle efficiency of the basic plant (60.2% down to 57.3%.)
Les Waganer developed a preconceptual design and cost estimate for the PPPL FIRE support structure. Most of the structure was 304/316 stainless steel. The intent was to keep the design simple to yield an affordable experiment with innovative approaches. A ROM cost was assembled with bottoms-up estimating, using in-house and vendor sources. The unit costs for the components were quite similar to those predicted by the ARIES System Code cost algorithms for basic structure after adjustments for number of units produced and credits for assembly, testing, contingency, and fees were considered.
Plasma Physics (ARIES-AT)
Chuck Kessel continues to work on vertical stability studies over a range of aspect ratios.
TK Mau discussed his investigation of finite plasma edge density. He has been using the plasma model Chuck Kessel presented at the last meeting. As the edge density increases from zero, there is a sharp increase in bootstrap current at the edge, which adversely affects the current drive system efficiency. It was affirmed that a non-zero edge density is needed to provide a radiating mantle to distribute a significant fraction of the plasma power to the entire first wall area.
TK Mau noted that GA is also looking at an AT-type of plasma, but their area of investigation focuses on startup scenarios and equilibrium operating points. Their design point is less ambitious than the ARIES-AT plasma design point. The results are to be presented at the upcoming APS meeting.
Systems Studies (ARIES-AT)
Ron Miller said he had received EQDISK files from C. Kessel. He is working to validate the ACS code to incorporate all the revised AT physics and engineering inputs. If he can validate the code, he intends to publish the ARIES-AT strawman prior to the SOFE meeting.
Rene Raffray noted that several engineering papers will be presented at the upcoming SOFE conference. Les Waganer is arranging for a meeting room for a short engineering discussion at the SOFE conference.
Rene discussed the evolution of the two different blanket designs to a common, high efficiency, safe blanket design. Lithium lead will be the only first wall and blanket coolant with no high-pressure helium internal to the blanket that might cause a safety problem in the power core. The blanket is designed to heat the LiPb coolant to a maximum of 1150°C, yet keep the SiC structure at or below 1000°C. He explained how the coolant is routed in three passes through the blanket; first through the first wall, then back through the side wall and rear walls of the blanket, and then to the interior large channels of the blanket for removal of the volumetric heating. The coolant is heated to the maximum temperature condition during the last pass through the interior of the blanket. He reviewed a viewgraph showing the pressure stress on the SiC structure due to pressure loading. There was some discussion regarding the pressure stress conditions and the SiC thermal conductivity values used. Hopefully these questions can be resolved during the SOFE side meeting.
Igor Sviatoslavsky concurred with Rene Raffray that the ARIES-AT first wall should be cooled with LiPb. The original UW design would not fare well with a seismic event. The new UW design consists of adjoined poloidal tubes. The coolant would be flowing upward through the tubes. The shape of the first wall tubes would vary from circular at midplane to elliptical at the upper and lower regions, but the flow area would remain constant. Igor provided sketches of the tube cross-sections and a table of parameters.
Laila El-Guebaly needs several pieces of data to help firm up the design basis for the ARIES-AT blanket and shield neutronics analysis. These are: SiC burnup fraction definition from Mike Billone, cost assessment of shielding design approaches from Les Waganer (promised in early November), cryostat design from Leslie Bromberg, and a design approach for the divertor from Mark Tillack or Rene Raffray.