1 Oct 95 Participants:
C. Bathke, J. Blanchard, J. Brooks, J. Crowell, L. El-Guebaly, T. Hua, H. Khater, V.D. Lee, T.K. Mau, R. Miller, I. Sviatoslavsky, D-K Sze, M. Tillack, L. Waganer, X. Wang, C. Wong
M. Tillack stressed the need to develop a self-consistent engineering strawman. Inputs are needed to C . Bathke by 10 October. Also need to conclude and document the FS, V, and LAR assessment reports.
D-K Sze reviewed the blanket and shield reference design. Shield used the ferritic steel (Tenelon) as shield filler and structure and is cooled with lithium to 300íC. Configuration from ARIES II was adopted with new wall loading requirements from the systems code. The vacuum vessel will be passively cooled. The first wall is to be bare vanadium (no Be coating). The blanket structural material is to be V4Cr4Ti which is better than the V5Cr5Ti alloy used in ARIES II because of improved DBTT capability. To address Li chemical reactivity concerns, argon cover gas will be used in the containment volume. Lithium coolant flows once through on the inboard blanket while on the outboard region it enters from the middle and flows up and down. The divertor coolant flow was not discussed - it may be a separate flow. Cooling manifolds will be developed for the October project meeting. Cycle efficiency is around 46%. The intermediate loop coolant is sodium. The IHX will be a double-walled heat exchanger with vanadium facing the lithium and SS facing the sodium. The approach to answer the questions related to the safety concerns of the lithium-self-cooled power plant is yet to be defined.
A cold trap will be used to separate the tritium from the lithium. Tritium inventory is estimated to be 130 g and the hydrogen will be around 60 kg in the lithium. One percent of the lithium coolant is to be circulated through the tritium removal process.
Jake Blanchard addressed the group about the capability to do disruption analyses. It was agreed the group should have, at some level, the capability to develop current analyses and load effects for Demo and perhaps a more detailed capability for future concepts.
Provisions for current drive and heating were discussed. The antennae are to be distributed above the outboard midplanes ( but not on the midplane). TK recommended a loop antenna but the area was around 15 m2 for a small thickness (~10 cm). But since the first few centimeters under the FW is valuable real estate, the group preferred the wave guide approach that used a 4 m2, full depth configuration. TK agreed to reevaluate the heating and current drive approach since we will be changing the aspect ratio from A = 4.5 to ~4.0.
Laila El-Guebaly discussed neutronics and shielding aspects. She will generate a new neutron wall load profile for the new aspect ratio. The distance from the "X-Point" to the divertor strike point was thoroughly discussed but for the moment 1.0 m was adopted (as shown by D. Lee in his drawings). Some shielding will be required behind the divertor to protect the TF magnets. She also covered the requirements for the other penetrations such as assembly gaps, divertor pumping ducts and current drive components.
Thanh Hua reviewed the ALEX test setup. Results of the differential pressure are anticipated to be available, hopefully by next week.
D-K Sze presented material from Hassanein regarding thermal effects of a disruption eroding 10-20 microns of [tungsten and Be?]. He will extend the analysis to vanadium.
Jeff Brooks presented some analyses he has done regarding ITER divertor erosion and redeposition. The old gas bag divertor approach had high erosion for most materials but the vertical plate approach seemed to be much better in erosion.
C . Wong discussed the PFC near and long term tasks to be accomplished. He then obtained agreement on actions to be completed by the October project meeting. [C. Wong to quickly publish a list of items and responsible people.] Pending review by Wong on the reversed shear physics configuration (working with El-Guebaly), Wong will recommend the radiative divertor slot length and width. The energy distribution inboard and outboard will also be reviewed and determined. The lifetime question will be reviewed and the maintenance approach will be in concert with the general Demo maintenance approach. Also for the moment, it is assumed the divertor will consist of bare vanadium surface that is cooled with lithium. The group may want to consider W as a thin layer of armor if this will be acceptable as Class C waste. Results of this analysis will be reported by H. Khater in the next project meeting.
Engr Meeting continued on 10/3
Participants : C. Bathke, L. El-Guebaly, T. Hua, V.D. Lee, T.K. Mau, R. Miller, F. Najmabadi, I. Sviatoslavsky, D-K Sze, M. Tillack, L. Waganer, X. Wang, C. Wong, H. Khater, J. Crowell
D. K. Sze reviewed the blanket and shield design approach and key factors to consider. The blanket and the primary shield will be controlled to 600íC, whereas the secondary shield will be 300íC and the VV will be passively cooled. Farrokh Najmabadi stressed the need for a rapid maintenance for the power core. To assist in this task and integration in general, a small group of people are to be selected (by M. Tillack and D. K. Sze) as a design integration group.
[In the way of review, the Engr Group met at ANL earlier and tentatively adopted the following design approach. Need to rapidly remove modules. Maximize size of modules. Keep secondary shield, vacuum vessel and structure as permanent components (except for those required to be removed for access). Include the Divertor with the Blanket maintenance. Reduce TF coils as tightly as possible. Keep TF and most PF coils fixed as permanent structure. Move two outer PF coils near center line up and down during maintenance actions. Use 16 TF coils. Investigate segmentation to facilitate maintenance, trading off size and ease of maintenance.]
I. Sviatoslavsky presented new design approaches to the blanket and shield segmentation and preliminary approach to support and lock the blanket and shield. F. Najmabadi preferred a single module approach, however neither approach has been quantified in regard to ease of maintenance and time to replace.
D. Lee presented a CAD drawing incorporating the Systems Code definition (A=4.5) of the plasma, blanket and shield, and the TF and PF coil size and placement. It was decided that the two smaller outer PF coils and shield should be moved for each maintenance action to provide clearance for module removal. C. Bathke will also investigate the COE impact to permanently relocate the two outer coils.
There was some recommended changes in the TF cap as shown. It should cover the top of the TF coils with a thin structure, not go between the coils. It can also stop at a smaller diameter to allow the divertor pumping port to be routed between the cap and the maintenance port. The FW should more closely follow the field lines. C. Bathke is to develop the code capability to determine the FW contour and forward that information to D. Lee the week of 10/9. F. Najmabadi will also forward to D. Lee the ARIES II maintenance approach and the CAD drawings of the TF Cap/Crown. This will allow D. Lee to incorporate the above changes into the CAD drawing for the Oct meeting. He will also be able to show the VV and various options for the segmentation of the life-limited components. Then we can assess the dimensions to be confirmed/changed and the maintenance approach to be followed. At that time we also can decide on the design approach for integrating the structure with the VV and the general approach for supporting all internal components.