NCSX NCSX Vacuum Vessel R&D, Risk Management and Manufacture NCSX Preliminary Design Review October 7-9, 2003 Princeton, NJ Mike Viola, Phil Heitzenroeder, Paul Goranson and Mike Cole for the NCSX Engineering Team NCSX October 7-9, 2003NCSX PDRMichael Viola 2 Outline Overview of NCSXs Vacuum Vessel Complexity Risk Mitigation Manufacturing Studies R&D and Vacuum Vessel Prototypes Cost & Schedule Summary NCSX October 7-9, 2003NCSX PDRMichael Viola 3 NCSXs Vacuum Vessel Was Recognized as Unconventional Right from its Conception Highly shaped Forming of Inconel 625. Need for tight tolerances Design has to accommodate assembly needs Modular coils have to be positioned over the VV; this requires all ports except mid period ports to be welded in place after the coils are installed. Vessel shape & size has to be compatible not only with plasma, but with divertors and space needed to slide the modular coils over it. NCSX October 7-9, 2003NCSX PDRMichael Viola 4 Consequently a Three-Phase Program Was Developed To Reduce Risk 1.Phase I: Received inputs on the design, specification, cost and schedules in limited studies during the Conceptual Design Phase. Goal: to obtain industrial inputs on the VV design, its specification, and cost and schedule. 1.Phase II: Two different vendors are presently fabricating partial prototypes of a critical region of the vessel. The forming, welding, machining, polishing, port removal and reattachment, and inspection processes will all be demonstrated and optimized. The prototype development and R&D Studies will provide a solid understanding of the manufacture techniques and reduce risk factors. Goal: to obtain a Final Design 1.Phase III: At the conclusion of the R&D phase, a fixed price contract will be awarded for the production vessel. The two vendors that have been selected for the R&D phase will result in at least two qualified vendors for the production articles, and provides an extra incentive to keep production costs (and bids) low. NCSX October 7-9, 2003NCSX PDRMichael Viola 5 Technical Risks Have Been Identified and Mitigated Through R&D, Design and Analysis. Potential Technical Risk #1. The vessel will not permit a high quality vacuum (leaks, outgassing, etc.) Addressed in the design, the procurement specification, and the manufacturing, inspection, and test plan. Minimize the number of welds. The welds will be full penetration with GTAW. The vessel will be leak checked at the fabricator after multiple heating and cooling cycles. The interior surfaces will be polished and cleaned according to accepted vacuum equipment standards. The main assembly flanges between field periods is welded. All the circular ports will have conflat seals. In addition to leak checking at the manufacturer, leak checking will occur after the port extensions are welded in place and prior to assembly of the three field periods. NCSX October 7-9, 2003NCSX PDRMichael Viola 6 Risk Management (continued) Potential Technical Risk #2. The vessel will not have the correct shape Mitigated by the 3-D CAD technology and the use of modern 3-D measurement equipment such as laser trackers and portable coordinate measurement systems. The vessel can be continuously measured and corrections made during the fabrication process, and intermediate heat treatment will be provided to reduce residual stresses that could cause distortion during operation. All the fabrication processes will be demonstrated and optimized during the R&D phase of the vessel procurement, where full scale, partial prototypes will be fabricated and measured. A spool piece is included between each field period subassembly that will be used to accommodate any misalignment between field period assembly flanges. NCSX October 7-9, 2003NCSX PDRMichael Viola 7 Risk Management (continued) Potential Technical Risk #3. The coils will not fit over the vessel Mitigated by the 3-D CAD technology, the use of laser scanners and/or multilink measuring systems to verify geometry, and using accurate scale models of the vessel and coils during the design and development processes. CAD models demonstrate available clearances. A 1/12 scale Stereo Lithography model of the present design also verifies gross assembly techniques. NCSX October 7-9, 2003NCSX PDRMichael Viola 8 Risk Management (continued) Potential Technical Risk #4. The vessel will fail mechanically Mitigated by analysis and conservative design criteria. Critical analysis, such as disruption load calculations, stress and deflection calculations and buckling analysis have been performed and are acceptable. The stresses will be compared to the ASME code, which provides a safety factor of 1.5 on yield for primary membrane stresses at the operating temperature. NCSX October 7-9, 2003NCSX PDRMichael Viola 9 Risk Management (continued) Potential Technical Risk #5. The vessel will not have adequate thermal performance Mitigated by using the same temperature control system successfully used for the NSTX vessel. The system provides twice the heating capability and eight times the cooling capability predicted by analysis. Multiple redundant paths ensure that minor blockages or minor leaks will not affect overall performance. NCSX October 7-9, 2003NCSX PDRMichael Viola 10 Risk Management (continued) Potential Technical Risk #6. The vessel will introduce static or transient field errors Mitigated by the choice of material and the strict adherence to stellarator symmetry. Inconel 625, has a relatively high electrical resistivity, about 50% higher than 300 series stainless steel. This results in an electrical time constant of less than 10 ms for the most persistent induced current path. In addition, the relative magnetic permeability of the material, even after forming and welding is very low, less than 1.01, so field errors due to induced magnetism should be negligible. Finally, the port locations and geometry are stellarator symmetric, so any currents that are induced in the vessel should also be stellarator symmetric. NCSX October 7-9, 2003NCSX PDRMichael Viola 11 Risk Management (continued) Potential Technical Risk #7. The vessel will not permit sufficient access for inspection, maintenance or reconfiguration of internal components Mitigated by providing as many ports as possible that are large enough for manned access. The three neutral beam locations each have a 13.5 x 34 inch oblong port that is accessible even with the beams installed. On either side of the neutral beam port are large flared ports with an inch minimum width and 36 inch height, providing a total of six more manned access ports. Finally, the large neutral beam port cover flanges can be removed if necessary. NCSX October 7-9, 2003NCSX PDRMichael Viola 12 Risk Management (continued) Potential Technical Risk #8. Field Joint results in too much distortion and is not leak tight. R&D is planned which will simulate the welding of the vessel field joints. NCSX October 7-9, 2003NCSX PDRMichael Viola 13 Risk Management (continued) Potential Fabrication Risk: Vendor is unable to make the vessel, the price is too high, or the vendor goes bankrupt Vendors have been chosen that are financially stable and have a proven track record of performance. We expect two vendors to be technically qualified by the Phase II program. As a fall-back, it is possible to revert to the other. NCSX October 7-9, 2003NCSX PDRMichael Viola 14 Consequently a Series of Manufacturing Studies Were Developed to Reduce Risk Phase I. Funded Studies in the Conceptual Design Phase. Goals: to obtain industrial inputs on the VV design, its specification, and cost and schedule. There were five participants. Study Findings: We found that not only could the vessel be built, but it could be built with a variety of techniques including Hot Forming, Cold Forming, Explosive Forming and Casting. The studies provided cost, schedule, and technical inputs. A plan was formed to pick 2 suppliers who offered viable manufacturing techniques for the prototype vacuum vessel. From those two suppliers, one will be chosen to fabricate the three Vacuum Vessel SubAssemblies (VVSA). Our sincere thanks to all the study participants!! Completed NCSX October 7-9, 2003NCSX PDRMichael Viola 15 Manufacture Dies are machined. Panels are cold pressed. (Segmentation determined by Vendor.) (Prototype consists of a 20 sector which involves about 5 segments) Measurements taken using CMM or gages Panels welded together on fixture Mirror every half period (60) More measurements taken (Heat treatment requirements evaluated during R&D) 60 segments married Ports welded on before cutting holes. permits leak check minimizes distortion Main flanges attached Leak check entire vessel and port welds between thermal cycling Ports cut off to leave stubs reinforces vessel permits port alignment Holes bored Vessel shipped 60 Degree Half-Period 6 Piece Segmentation Scheme NCSX October 7-9, 2003NCSX PDRMichael Viola 16 Phase II of the Manufacturing Studies Is Now Underway Goals: To produce a prototype VV sector. To provide experience in manufacturing prototypical parts so firm fixed price proposals can be developed which do not have excessive contingency built in. Prototype consists of a 20 sector (chosen for good demonstration of shape forming) and a vacuum port assembly to demonstrate their ability to produce vacuum-quality welds. NCSX October 7-9, 2003NCSX PDRMichael Viola 17 Tolerances Were Developed with Prototype Suppliers Profile tolerance on outer vacuum surface is bilateral i.e either side of reference surface. Material thickness tolerance shall be per requirements set forth in ASTM B443. The minimum thickness after forming shall be Thinning below the stock thickness shall not occur over more than 10% of the total poloidal circumference of any cross-section. NCSX October 7-9, 2003NCSX PDRMichael Viola 18 Phase II of the Manufacturing Studies Is Now Underway Goals: The two Prototype suppliers Major Tool and Rohwedder have submitted their MIT plans and were authorized for fabrication on August 7 th. Major Tool has begun fabrication of the dies and has one complete set. Rohwedder is having difficulties with their subcontractor but has made a proposal to resolve the issue and is vigorously working a solution that will be acceptable to us. NCSX October 7-9, 2003NCSX PDRMichael Viola 19 Phase II of the Manufacturing Studies Is Now Underway (Major Tool Die/Punch set) NCSX October 7-9, 2003NCSX PDRMichael Viola 20 Phase II of the Manufacturing Studies Is Now Underway (Major Tool Inspection Gages) NCSX October 7-9, 2003NCSX PDRMichael Viola 21 Phase II of the Manufacturing Studies Is Now Underway (Major Tool Welding Form) NCSX October 7-9, 2003NCSX PDRMichael Viola 22 Phase II of the Manufacturing Studies Is Now Underway (Major Tool Welding Form) NCSX October 7-9, 2003NCSX PDRMichael Viola 23 Vacuum Vessel Phase II Manufacturing Studies / Prototype Fabrication Schedules Complete Prototypes Scheduled for delivery in March 04 The FDR on the Vacuum Vessel is scheduled for April 04. Produce a Final Manufacturing / Inspection / Test / Quality Assurance Plan for the Production Vacuum Vessel Mid - June 04 This will be refined based on their experience in manufacturing the prototype. Their Firm Fixed Price and Schedule Proposal will be developed based on this. Produce a Firm Fixed Price and Schedule Proposal To be completed by the end of May. A Subcontract Proposal Evaluation Board (SPEB) will begin evaluations of the two teams Prototype performance in June. They will evaluate the two teams Proposals when received in late June and submit their findings and recommendations for the Production Subcontractor to the Procurement Official by mid July. This will lead to the Production Subcontract Award by the end of July. NCSX October 7-9, 2003NCSX PDRMichael Viola 24 Vacuum Vessel Phase II Manufacturing Studies / Prototype Fabrication Cost & Schedules NCSX October 7-9, 2003NCSX PDRMichael Viola 25 Phase III of the Vessel Fabrication Is Upcoming Goal: To build the Vacuum Vessel within Specification, On Time & Within Budget. It is our intent to select one subcontractor for the vacuum vessel assembly (i.e. 3 vessel sectors and all associated ports). The selection will be based on firm price/schedule proposals, evaluation of the prototypes, and our experience in working with them during these efforts. The earlier efforts will provide the technical and manufacturing experience base to make this possible. Scheduled to begin fabrication in July 04 with delivery in September 05 The detailed manufacturing studies have yielded a budgetary cost of the VVSA of $2.9M NCSX October 7-9, 2003NCSX PDRMichael Viola 26 Summary Phase I is complete. Risks have been identified and steps put in place to mitigate them. Phase II - The Prototype Vacuum Vessel is under construction. The experience gained from this 20 segment will provide the experience and knowledge to build the Vacuum Vessel Subassembly with great confidence in the design and cost factors. Major Tool has fabricated several die components Rohwedder is vigorously working a solution that will be acceptable to us. Phase III is anticipated with great confidence. Each of the 2 prototype suppliers have already begun the draft of the MIT/QA plan for the VVSA.