Summary of NCSX SIT Meeting of Monday, Jan. 27, 2003
1. Announcements (Hutch)
DOE-PAO has approved the project's proceeding with the award of the MCWF and VV R&D contracts and the authorization of initial Planning and Analysis tasks. Decisions on authorizing prototype fabrication are deferred.
2. QPS Winding Form Manufacturing Studies.
The option of adding the QPS WF manufacturing studies to the NCSX contracts as an additional task was discussed.
ACTION: Hutch follow up with PPPL Procurement concerning possible issues.
3. MCWF Critical Issues Peer Review.
A set of notes for briefing R. Goldston and R. Hawryluk on the result of the Jan. 23 peer review was prepared. Briefing notes are attached.
ACTION: Mike to develop an analysis plan for estimating eddy current effects on plasma with the present configuration of breaks. Also analyze the case with no poloidal breaks to strengthen justification. Identify appropriate scenarios and time slices to analyze, schedule, decision points. Work with Wayne to coordinate priorities.
ACTION: Wayne follow up with Larry Dudek on peer review report and closeout of chits.
Feedback from Goldston/Hawryluk briefing (see Attachment) later on Jan. 27:
* Approved proceeding with MCWF R&D contracts in parallel with analyzing eddy current effects on poloidal break and developing design details. Need eddy current analysis plan. (MZ action item, above).
* Concerned that MCWF R&D was starting with out-of-date design. Need to exercise careful oversight to avoid doing work that will have to be repeated. Is the contract structured with task-by-task work authorization and spending limits? (ACTION: Hutch follow up with procurement.)
* PDR deliverables (MIT/QA plan and cost & schedule estimates) should be based on the design we plan to build. Project needs to finalize its design details and update the models and drawings for suppliers ASAP.
4. Other Critical Issues (Wayne)
a. Developing the VV geometry consistent with assembly requirements is a struggle. Best case to date would shrink PFC-to-VV envelope to near zero in tight spots. Several possible solution paths were suggested:
- Re-visit one-coil-at-a-time assembly.
- Re-shape the winding packs (reduce their radial depth).
- Add additional vacuum vessel joints.
- Improve trajectory optimization algorithm
Further discussion needed with Zarnstorff, Nelson, Williamson, Brooks. ACTION: Brad.
b. Modular Coil cooling configurations. We do not have a design yet.
5. Field Work Proposals. (Ron)
FY04-05 budgets are due to PPPL Budget Office by Feb. 10. ORNL guidance on QPS needed. (ACTION: Jim)
6. CDR & PAC-6 Recommendations
Status of project responses to CDR and PAC-6 recommendations was updated by GHN based on the overwhelming volume of input, and posted on NCSX web site. Follow-up contacts with responsible individuals will be made.
7. Next SIT Meeting: Monday, Feb. 3 at 11:00 a.m. EST.
Summary by:
Hutch Neilson
NCSX Briefing for R. Goldston and R. Hawryluk
Jan. 27, 2003
Basis for proceeding
with a winding form incorporating one poloidal break.
(PAC-6: Identify the issues and make a plan to
address them. Justify need fully.)
· With no poloidal break, time constant is 70 ms (slow compared to minimum IP rise time of 60 ms, ábń rise time of 100 ms).
· With one poloidal break (and 15 toroidal breaks), time constant is reduced to 18 ms.
· Rough Dcost of one break $540k (~8% of MCWF cost).
·
Engineering
issues and how they will be addressed:
o Distortion when break is machined:
manufacturing R&D.
o Insulator damage from process chemicals: manufacturing R&D.
o Electrical inspection of break: sandwich design.
o Local deformations and/or insulator faults due to discontinuity in winding support: analysis, optimize poloidal location of break.
o Inaccessibility of tee-to-tee bolts (plasma side) may complicate maintenance: design, with feedback from manufacturers.
o Mechanical or electrical failure risk and recovery: design and analysis.
·
Cost justification: clear plasma control benefits of
one break vs none.
·
Plasma
control issues and how they will be addressed (MZ developing a plan with
timeline and decision points with Wayne, Art, LPK):
o Estimate eddy current effects on plasma with present break configuration: EM analysis for one or more scenarios.
o If effects are intolerable, options are:
§ Compensate via plasma control strategies (e.g., use of trim coils)
§ Restrict operating scenarios.
§ Modify shell design to reduce time constants (make thinner to reduce time constant, more holes or cuts to break up eddy currents).
·
Future
design changes which may affect time constants:
o Sizing and location of holes for diagnostic access.
o Adjust shell thickness if necessary to solve local stress problems.
o Remove material wherever possible to reduce weight and cost.
· Thermal conducting layer (0.090 in. thk. copper) is adequate to conduct heat from windings to cooling tubes.
· Issue is details of the design concept (e.g., thermal stresses, location of the cooling tubes) and manufacture of the copper layer.
· MCWF proposers struggled with Cu cladding requirement. Problem is coming up with an inexpensive process that satisfies tolerance requirements on finished product. Conclusion: more homework required.
· Our approach:
o Take it out of the supplier MCWF R&D task: let them concentrate on casting, machining to achieve high dimensional accuracy.
o Basic concept is mechanically applied copper strips prior to winding.
o Conduct an internal R&D program to address conceptual and manufacturing issues over next three months. Get Bob Parsells involved.
· Strawman budget proposed by Brad for ±0.060 in. (1.5 mm) tolerance seems reasonable:
o ±0.020 in. for winding form / copper cladding
o ±0.020 in. for winding packs / VPI process.
o ±0.020 in. for assembly.
· Maintain ±0.010 in. tolerance for unclad MCWF, pending further feedback from suppliers. Need to anticipate it might be difficult / costly to achieve. ® plan for tolerance recovery.
· Evaluate options for tolerance recovery at each step:
o custom-shim copper layer to improve winding surface accuracy.
o custom-shim between winding layers to improve winding pack accuracy.
o custom-shim between coils to optimize position of as-built coils.
o field-error correction coils
· Determine how best to take advantage of possibilities to relax tolerances in regions of the coil far from plasma.
Project response to
the chits.
· Awaiting Larry Dudek’s report.
What this prototype
activity is seeking to achieve.
· Develop processes for manufacturing the MCWFs, with emphasis on the difficult issues: translation of CAD data to manufacturing data, complex geometry, measurement, achieving dimensional accuracy and low magnetic permeability, cost and schedule.
· Obtain feedback on possible ways to improve manufacturability.
· Obtain more accurate cost and schedule estimates for manufacture for PDR.
· Build prototypes: demonstrate processes, confirm estimates, provide winding forms for full-scale prototype winding.
· Qualify two suppliers and obtain fixed price and schedule proposals for production from them.
· No, because models and drawings still need to be updated to reflect recent changes: M50 coils, poloidal break details, removal of cladding.
· There will be a review of the prototype drawings and specs before they are released for fabrication, per PPPL procedures.
· Yes, the documents and specs currently available, though based on the M45 design, are adequate for initial supplier tasks: alloy selection, analysis of casting and machining processes, development of preliminary MIT and QA plans, and budgetary cost/schedule estimates.
· We need early vendor feedback on certain design issues we are addressing for the PDR, e.g., tee-to-tee connection at breaks, tolerance implications.