NCSX Cryogenic Systems WBS 62 Fabrication Operations and
NCSX Cryogenic Systems (WBS 62) Fabrication, Operations, and Maintenance Division Engineering Department Princeton Plasma Physics Laboratory NCSX Performance Baseline Review November 18 -20, 2003 Princeton, NJ
NCSX WBS 62 OVERVIEW The stellarator core is supported by three cryogenic facility systems: – WBS 621 presents LN 2 and LHe to the machine area. – WBS 622 performs heat removal from the field coils – WBS 623 circulates cold GN 2 within the cryostat and around the core’s structures 2
NCSX SIMPLIFIED LIQUID CRYOGEN DISTRIBUTION The cryogen distribution system makes full use of legacy equipment at CSite. The 9200 gallon LN 2 dewar is ready for service. The helium off-load gear exists but requires general overhaul. Initial NB Ops will include portable LHe dewars only. 3
NCSX PERSONNEL SAFETY The normally-closed LN 2 valve on the previous slide responds to an oxygen deficiency sensor array. Also provided in th e plan is a highthroughput blower system to vent the machine area in the event of a low oxygen condition. 4
NCSX SITE EQUIPMENT STATUS NCSX The 9, 000 gallon LN 2 tank is in service and supports the Hall Thruster Project at about 200 gallons per day The NCSX PDR heat load is about 5200 gallons (less than one trailer) per plasma day This tank is fine! 5
NCSX SIMPLIFIED LN 2 FIELD COIL COOLING SUPPLY A pressurized, sub-cooled LN 2 heat removal loop is planned for the field coils. A vapor removal trap will be provided. 6
NCSX SIMPLIFIED GN 2 CRYOSTAT COOLING SUPPLY The actual cryostat attachment points for the insulated supply and return ducts have not yet been selected. Top and bottom center are favored to promote a flow pattern having radial symmetry. Dominant loads are heat leakage from bakeout and from port extension penetrations. The cryostat’s nitrogen pressure will be kept slightly positive relative to the atmosphere. 7
NCSX PDR Recommendation The PDR Panel had one recommendation for WBS 621 & 623: Fund vaporizer units (similar to these TFTR units) to better allow humidity control within the cryostat during cooldown. NCSX will fund a vaporizer outside of the baseline MIE plan. 8
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NCSX WBS 62 Total Estimated Cost ($k) excluding contingency Sum of cost WBS Cost Category Expense class 621 622 2) Title I & II Labor/Other $36 $43 $39 $118 $0 $0 $61 $116 $108 $285 $80 $114 $189 $383 $177 $273 $336 2) Title I & II Total 3) Fabrication/Assembly (incl title III) Labor/Other M&S 4) Installation/Test Labor Grand Total 623 Grand Total $786 10
NCSX WBS 62 SUMMARY • Site credits such as the existing LN 2 tank keep costs lower than starting with an empty sheet of paper. • Cryogen delivery requirements are understood. • A sound basis exists for cost estimates. Historic construction costs at PPPL were used as a basis for estimates. • Vacuum jacketed piping with multi-layer insulation is of low technical risk. • PDR recommendations will be embraced. • WBS 62 plans are ready for next scheduled activities. 11
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