ARIES Documents -- Meetings ArchiveARIES Conference Call, 11 December 2012
Documented by L. Waganer
Les Waganer mentioned that the next project meeting will be held at UCSD, Tuesday, January 22 (all day) and the half day of Wednesday, Jan 23, 2013. Mark Tillack has arranged the meeting room. Due to room availability restrictions, the meeting will commence at 10:00 on Tuesday. Send Les your presentation titles for incorporation into the agenda. The next ARIES conference call will likely be in early January with the date to be determined.
There will be a US/Japan Fusion Power Plant Study meeting in Kyoto, Japan on the 26-28 of February, 2013. Anyone wishing to attend should contact Mark Tillack or Farrokh Najmabadi.
There will be an ARIES peer review around August 2013, pending arrangements with OFES personnel and the peer review committee. Farrokh is preparing a list of suggested presentations and personnel attending. The review format will be similar to the 2000 ARIES review.
ARIES Technical Efforts
Nuclear Heating - Laila El-Guebaly revised the ARIES ACT-1 radial builds. She thickened the inboard blanket and structural ring to reduce the nuclear heat leakage to the VV and low-temperature shield. The heat leakage is now about 2% of the thermal power as compared to the previous value of 5-6%.
3-D Activation Analysis and Decay Heat - Laila initiated the ACT-1 3-D activation analysis. Carl Martin is currently developing the ANSYS model to obtain the temperature responses during LOCA and LOFA events. Laila will determine the preliminary radial build thickness for the ARIES ACT-2 that will meet the tritium breeding requirement and protect the magnets.
ACT CAD Definition - - Xueren Wang has been developing the preliminary ACT-2 power core definition. He is also working on a response to the Team's suggestion to provide space for vacuum pumping ducts at the bottom of the power core. Obtaining sufficient space is difficult because of the proximity of the TF and PF coils, structural supports, coolant manifolds and piping at the bottom of the core. However, Xueren believes he has sufficient space for the lower vacuum ducts in addition to the upper vacuum ducts.
More on SCLL Power Core Definition - Mark Tillack continued the power core definition discussion, mentioning that Christina Koehly is working on the inner region manifolding and will provide more details in the January project meeting. Mark also mentioned that the divertor region with the manifolds, VV ducts and shielding is a very preliminary design with a lot of interaction with Laila, Siegfried Malang and Xueren to make sure all requirements are met.
Power Core Materials - Arthur Rowcliffe pointed out a couple of items addressed in recent e-mails related to materials requirements and candidate materials for the ARIES ACT power core. The temperature limits during accident conditions which would allow re-use of the Fe-based structural alloys was discussed. For the RAFs (F28H and Eurofer), the maximum temperatures should not exceed the tempering range of 700-750°C and temperatures above 800-850°C would probably result in volume changes and embrittlement resulting from the ferrite to austenite phase transformation. Temperature excursions for the ODS martensitic steels, such as EuroferODS, will also be limited by the ferrite-martensite transformation temperature 800-850°C. However, the ferritic ODS materials, such as the nano-structured 14YWT alloy, have a strong advantage in this regard because of the very high thermal stability of the nano-structured dispersion and absence of a ferrite-austenite transformation and probably could withstand temperature excursions into the 100-1050°C range. The possible utilization of tungsten alloys containing rhenium hafnium and carbon was raised. There are indications from work conducted for various space nuclear power systems that addition of Re in the 2-4% range will confer some increase in ductility. An optimum distribution of HfC particles, which occurs at the stoichiometric Hf:C ratio, confers a significant level of recrystallization resistance as well as maximizing creep strength. Further examination of the data is in progress.
Divertor Fatigue and Thermal Analyses - Jake Blanchard said he is starting to analyze the plate/finger divertor design that would handle the higher heat loads, especially those associated with ELMs and disruptions. He believes he will have data in time for the January meeting.
Jake would like to initiate the disruption analysis on the VV, but he has not received the VV CAD model. Mark and Xueren thought the model was ready for transmission to Jake and will check into its status.
Plasma Modeling in the Divertor Region - Tom Rognlien and Marv Rensink provided Chuck Kessel with an outline of possible content of the final report chapter for the plasma and divertor physics modeling. They also continue to pursue divertor plasma solutions that are detached or partially-detached for the desired divertor region geometry. For this recent modeling, they are using the DEGAS2 neutral Monte Carlo simulation code to obtain refined description of neutral particles with fixed plasma solutions (thus not fully self-consistent). Lower neutral temperatures (and thus pressures) are found in the private flux region, which is the direction of the ITER Organization's solutions for ITER.
They have also performed some multi-species impurity simulations, again with a frozen main-plasma background obtained using the simpler constant-concentration impurity model that neglects transport effects. Initial results for neon find much lower impurity radiated power for the multi-species model, which is a concern. Further work to clarify the power reduction will include variations of impurity fueling/pumping rates/locations, and likely a self-consistent multi-species-impurity/main-plasma solution.
Safety Analysis - Lee Cadwallader represented Paul Humrickhouse, who could not attend the call. Lee said Paul is working on the LOFA scenario and hopes to have some results by the January meeting.
Plasma Steady State Modeling - Alan Turnbull said Holger St. John is working with the equilibrium data and hopes to have results by next week.
Divertor Reliability Modeling - Tom Weaver noted that Dave Schwab of Boeing is supporting the divertor reliability modeling. They are incorporating the divertor material properties. Tom said that the intent is to complete the analysis by the end of the year and provide results at the January meeting.
Physics Code Results - Chuck Kessel has conducted five time-dependent simulations for the 6.25 meter DCLL power core. This analysis was a lot more time-intensive than he had previously thought. He is using the LH heating option. He is also using the present Wang coil positions in his code. He is concerned about moving the coils to accommodate the new vacuum port ducts or increasing the number of coils. However Xueren Wang is confident the present coil number and locations can be retained. Chuck would appreciate receiving Xueren's latest DCLL CAD drawings, even if they are preliminary and subject to change.