ARIES Documents -- Meetings ArchiveARIES E Meeting, 16 June 1999
Documented by L. Waganer
AdministrativeThe dates of the next ARIES meeting were affirmed as August 9 through 10 or 11 depending on the start time on Monday. L. Waganer is to solicit the team to determine if starting on Monday morning or afternoon is preferred. The meeting will last for two full days. Farrokh Najmabadi summarized the Advanced Design Studies results to date, status, and future plans to the VLT PAC meeting on 8-9 June 1999. He described the preliminary results and the future plans for the Advanced ARIES-RS concept. The PAC group was very positive about the ARIES Neutron Study assessment results to date and the more detailed study effort planned. Farrokh mentioned the possible ARIES investigation next year of the stellarator, RFP, or an IFE concept. Mark Tillack provided a link to Farrokh's presentation materials, see TALK . Several of the advanced concepts (NSTX, Titian, general ST) advocates were at the meeting and voiced support for the ARIES assessments to date. Our findings were not always identical to those of the advocates, but they understood our guidelines and technical approach. Farrokh was not sure of the PAC role in the guidance of the ARIES project. Bill Dove clarified that PAC would provide guidance and support, but OFE is ultimately responsible for the ARIES project goals and direction. Farrokh also stressed that the pace of ARIES investigations seems to have slackened. He understood the present uncertainty relating to the US fusion program and the lack of solid guidance. But this is a critical time when solid and credible results are needed to formulate program direction. Do not let up - keep working on the projects at hand.
Snowmass - Farrokh emphasized that we need to have a strong technical impact at Snowmass, both at the meeting and preceding it. The Snowmass meeting is not intended to be a presentation style meeting; rather it is a workshop format. As such, it is important to provide the session and discussion leaders with technical data to stimulate and substantiate discussion.
Systems StudiesRon Miller informed the group that he has the Aries Systems Code running and producing strawmen for the ARIES-ST concept. He has implemented changes on the radial build, shield, and cost corrections for the heat transport system. The results have been posted on the ARIES systems web site. Ron believes it reflects the final physics and engineering design. The thermal conversion efficiency has been adjusted downward to 45%. The beta value has been lowered as recommended. The inboard PF coil set has been repositioned.
Neutron Source StudyDon Steiner reviewed the approach to the Neutron Source Study, namely to assign "homework assignments" to collect relevant materials and to assess existing information to determine an approach or concept that would yield the most "desirable" product along with identification of the related technical issues. This would enable a decision on a more in-depth study and analysis of the selected concept.
Les Waganer reported that he has just begun to examine the product options proposed for the neutron source. The listing he presented to the ARIES team last yeargenerally encompasses the products and concepts identified to date. The next action is to collect detailed information and technical data on the selected concepts/products.
Don Steiner discussed the interaction between fusion, fission, and accelerator communities to provide a source of neutrons for transmutation or energy production. Don mentioned the PLATO project being sponsored by Curt Bolton.
Ron Miller reviewed the need to have appropriate metrics to provide a meaningful evaluation of the alternate neutron sources being considered. Since this aspect is common to the PLATO project, he will be collaborating with that project.
Mark Tillack is to compile and assess the engineering and nuclear performance of the proposed concepts. He is planning to use the metrics identified by Ron to measure the performance. The support ratio of number of LWRs may be a good measure. Mark was concerned about the bulk of the technical information regarding these approaches. Don Steiner said he would help Mark review and categorize the information as he felt there was a lot of commonality.
Dave Petti is responsible for the environmental, safety, and licensing implications of the fusion neutron source applications, especially the plutonium disposition and radioactive waste transmutation. Dave was not on the call.
Plasma Physics (Advanced ARIES-RS)Steve Jardin informed the group that both PPPL and GA (Vincent Chen) are optimizing the plasma physics parameters for the Advanced ARIES-RS concept. Specifically, they are doing a beta optimization to increase the stable beta from that of the previous ARIES-RS project. To date, they have been rather successful, obtaining a beta value of 8.23. This was obtained by moving the plasma closer to the X-point and increasing the triangularity of the plasma. General Atomics will host a coordination meeting with PPPL on June 28. All interested persons are welcome.
Engineering (Advanced ARIES-RS)Laila El-Guebaly stated that she has been revising her analyses for the UW self-cooled LiPb/SiC design using the new Advanced ARIES-RS engineering parameter data set. She was questioning the position of the stabilizing shell. She asked if the LiPb coolant could be assumed to function as a conducting, stabilizing shell (for kink stability?). It is located very close to the first wall, it is conductive, and it has considerable mass. Since it is fluid, does that reduce or eliminate its effectiveness as a stabilizing shell? This topic was discussed and Mark mentioned that because the kink instabilities act on very short time scales, the LiPb coolant would effectively act as a solid. The vertical stability shells would be located behind the shield as defined in the ARIES-RS report. Rene Raffray noted that the first wall and blanket material composition by zone for the dual-coolant LiPb/He/SiC design will be sent to Laila.
Igor Sviatoslavsky showed a new power flow diagram for the self-cooled LiPb/SiC design with an increased temperature in the primary (1000°C LiPb) and secondary loops (950°C He) (see figure). These changes yielded an estimated thermal conversion efficiency of 54.7%. The flow rate of the LiPb was also increased from 1.2 m/s to 3.1 m/s. The recommended LiPb outlet coolant temperature is higher than the ARIES-ST design, which was 700°C. There was concern that there has been no data to indicate compatibly of LiPb with SiC at this temperature range. Impurity in the SiC fibers, especially oxygen, is very detrimental to the compatibility of the coolant and the structure. Since it is crucial to have a high coolant temperature, we should proceed with the chosen materials and operating temperatures. However, we must explicitly highlight the need to have confirming material compatibility testing.
It was suggested that Ron Miller conduct a COE trade study to determine the impact of the outlet blanket coolant temperature and resultant thermal cycle efficiency. ReneRaffray has also determined coolant temperatures and cycle efficiencies. Rene and Igor should collaborate on their analyses and determine a common configuration, thermal conditions, and system efficiency for use in the engineering design and system code analyses.
Rene Raffray noted that two design approaches for SiC/LiPb blankets were presented at the Madison meeting by UCSD and UW, respectively. The parameters will include the latest SiC properties recommended by Mike Billone. A common set of input parameters is being evolved with input from UW, ANL and UCSD so that the design and analysis of each option can be done on a consistent technical basis. Rene stated that the first wall and blanket material composition by zone for the LiPb/SiC/He blanket will be sent shortly to Laila for the neutronic analysis of this concept. He also agreed to coordinate with Igor in using a consistent Brayton cycle analysis procedure.
Dai-Kai Sze just returned from Japan and had no new input on the use of LiSn breeder and coolant design approach.
Mike Billone reported that he has been working on obtaining SiC mechanical and thermal properties to use as design properties. To be valid, the data must be tested after irradiation and within the operating temperature range. One SiC material is thought to have excellent properties, but Mike wants to make sure the data is valid before releasing the data for use. He also stressed that the lifetime of SiC should be determined by a burn-up fraction of 3%, not a certain dpa value.
Leslie Bromberg attended a High Temperature Superconductor (HTS) workshop at ANL, which addressed the performance and costing of HTS. The production installed cost of $200/kg for HTS conductors is considered to be the minimum attainable. Leslie is collaborating with ORNL and PPPL to develop a set of preliminary design criteria. These data will be discussed at Snowmass. There are three options to be evaluated:
It was suggested that Leslie Bromberg work with Les Waganer to determine if the cost of magnet structures could be significantly reduced with innovative fabrication techniques.
Large Fusion Power Plant Study
Les Waganer reported on the kickoff meeting of the Large Fusion Power Plant study being directed by John Sheffield of ORNL. Duke Engineering and TVA are responsible to determine the impact of integrating a large electric plant (3-5 GWe) into their electric grid. Their major concern was the loss of planned and unplanned outages of that magnitude. Even though these are relatively large utilities, they still envision they would have to substantially increase their reserve capacity. They would rather pay for unused excess capacity than pay extremely high spot prices to cover peak demands due to forced outages. Joan Ogden of Princeton University is responsible for the hydrogen product and marketing strategy. She believes that hydrogen produced by off-peak, surplus electricity can be a profit-making venture. TVA currently uses pumped storage to help level its peak and surplus electricity. The best approach for making hydrogen seems to be the high temperature electrolysis process with desired temperatures above 800°C. Les Waganer is reviewing the best product for the large fusion facility. He is also responsible for the engineering aspects of the fusion plant and integrating it with the hydrogen production facility.