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NCSX. WBS 17 Design Status Informal Update. January 6, 2005. Old: WBS 171 provides the cryostat insulation system to isolate the stellarator from thermal load and atmospheric exposure including moisture - PowerPoint PPT Presentation
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NCSX
WBS 17 Design Status
Informal Update
January 6, 2005
NCSX
January 6, 2005 2
NCSX
WBS 17 Scope
• Old:
– WBS 171 provides the cryostat insulation system to isolate the stellarator from thermal load and atmospheric exposure including moisture
– WBS 172 provides the radially-translating base support structure to allow machine assembly and project-long gravity support / CTE compliance
• New:
– WBS 17 was selected as the home for the VVSA spacer assembly fixtures
January 6, 2005 3
NCSX
WBS 171 Approaches
• CDR Approach:
– The CDR plan for the cryostat was an assembled frame of rigid supports which would be subsequently insulated with urethane or other foam in a manner similar to that of large, rigid LN2 vessels
– Pro: Cost effective
– Con:
• Extremely difficult to perform without a mess
• Huge ES&H issue (methylene di-isocyanurate emerging from firehose)
• Access to machine would require cutting and subsequent re-spray to restore
January 6, 2005 4
NCSX
WBS 171 Approaches (cont.)
• Current Approach:
– A system of bolt-together insulation modules (J. Rushinski) has been designed
– Pro: Demountable, no cutting and subsequent spraying to restore
– Each fundamental module form can be configured with a blank insert or a custom insert for port extensions, coil services, etc.
– Potential for large volume production runs
– Joints, midplane supports need additional design work
January 6, 2005 5
NCSX
Fiberglass Construction
Approx wt. 8,000 # (As Shown)
January 6, 2005 6
NCSX
WBS 171, Insulation
• Penetrations
– Use of Robert Childs’ (C-Mod) system of Inspec Solimide foam with inner and outer fiberglass/silicone vapor barriers – No re-invention here
• Bulk Insulation
– Two part foam has been largely dismissed. NCFI, the Shuttle’s foam supplier, cites CTE concerns that are best avoided if at all possible.
– Martin Marietta/New Orleans, Kennedy Space Center, and NCFI seem to be under a gag order on the topic of external tank insulation topics.
• The NCFI person threw a bone with his “avoid two-part” comment
• Anecdotes available
January 6, 2005 7
NCSX
WBS 171, Insulation (continued)
• Bulk Insulation, continued
– Dow’s Trymer 2000/4000 polyisocyanurate custom-cut board stock seems a best candidate for filling insulation modules
• K=.19 BTU/in*hr/ft**2 or R-6.5/in
• Lowest available CTE for rigid pedestrian stock
• Similar to C-Mod approach
• Small gaps in layered fill can be filled with expanding polyurethane foam with tolerable personnel protection measures
January 6, 2005 8
NCSX
WBS 172 Approach
Approach:
• The spirit of the CDR design is largely embraced
• Gone, however, are the tri-axial thermal breaks in each of 12 towers
January 6, 2005 9
NCSX
WBS 172 Approach (continued)
• Each column top is provided with a Lubrite (grease impregnated bronze) skid plate familiar in oil patch industries. The skid plates (shown in brown) reside just below the tower finials that actually penetrate the cryostat.
• The above skid plate with appropriate steering/capturing hardware render the triax design unnecessary
• Concerns regarding toroidal loops will drive the presence of DC breaks in the 12 horizontal pipe sections
January 6, 2005 10
NCSX
WBS 172 Approach (continued)
• T. Brown requests an iteration on the intersection of the tower finials with the radial tie castings
Other:
• The 12 DC breaks for the horizontal stiffening tubes will be provided without argument.
– An electro-magnetics analysis of any need for loop interruption near the floor is probably prudent.
– Breaks cost $$$$. The rebar in the floor is certainly without isolation.
January 6, 2005 11
NCSX
WBS 172 New Scope
• Recently added to WBS 17 is the mechanical manipulator plan for supporting the VVSA spacers during the final assembly motions.
• While this scope does not initially appear difficult, the designer will better know in one or two weeks if any significant issues exist.
January 6, 2005 12
NCSX
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