NCSX Cryostat WBS171 Steve Raftopoulos NCSX Cryostat WBS171

NCSX Cryostat WBS-171 Steve Raftopoulos NCSX Cryostat WBS(171) Manager SC Project Review of NCSX, April 8 -10, 2008

Table of Contents • Introduction • Requirements • Interfaces • Design plans • Procurement plans • Cost and schedule estimates • Staffing • Risk Assessment SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 2

Introduction The cryostat (WBS 171) is an insulating, semi-hermetic barrier that will allow the surrounding of the stellerator core with a cold nitrogen atmosphere down to a temperature of 77 K. The semi-hermetic nature of the cryostat excludes the components of atmosphere from approaching the stellerator core in the design temperature range (77 K to 311 K). SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 3

Requirements 1. 2. 3. 4. 5. 6. 7. 8. 9. Must be gas-tight to internal positive pressure. Must provide penetrations for vessel extensions, electrical & hydraulic lines, stellerator supports, etc. Shall be of demountable design. Shall withstand vacuum boundary displacements (~1/4” radial) due to thermal expansion/contraction. Shall withstand displacements (~1/4” radial) due to movement of the coil/coil support structure during magnet pulse. The cryostat design, including penetrations and joint sealing, shall limit the influx of ambient heat to about 13. 9 k. W (includes WBS 172, machine base). Shall be have provisions for custom configuration. Cryostat panels shall contain a feature allowing the admission of ambient temperature nitrogen gas. Shall be compatible with all indentified ES&H requirements and best practices. SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 4

Interfaces • MECHANICAL – EVERYTHING is either within or passes through the cryostat. A system interface document will address all interfaces, including planned (and unplanned) maintenance. • ELECTRICAL – Coil buss work – Signal and control cabling • ENVIRONMENTAL – Test cell (maintain environment safe for occupation) – HVAC (much nitrogen gas must be vented SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 5

Design Plans • The current cryostat concept has double mechanical strut located at the upper, outer, and lower aspects of each TF coil – Basic shape is described by struts on radial planes SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 6

Design Plans • An FRP panel bridges two struts as a substrate • A glued 16 cm pyramid of polyurethane foam is applied to the substrate SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 7

Design Plans • Lapped layers of flexible foam laid into the steps of the rigid foam pyramids with clamping/beauty panels finish the assembly SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 8

Procurement plans • In this modular panel design, components are common “off the shelf” items, readily available and inexpensive. • Design incorporates “loose” tolerances, intentionally chosen to keep costs down. “Woodworking” tolerances apply. • WAF includes hours for in-house production. SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 9

Cost & Schedule Estimates SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 10

Staffing • • • WBS manager/Technical Expert – 1500 man-hours budgeted Cryogenics Consultant – 1000 man-hours budgeted Thermal Analysis - 360 man-hours budgeted Designer – 1420 man-hours budgeted, individual is identified. Fabrication - 3740 man-hours budgeted for PPPL Technical Staff Installation – Not budgeted in this job – (performed by in-house staff under WBS-7) SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 11

Risk Assessment • Low Design Maturity, High Complexity • Risk • The modular panel design places priority on flexibility and accommodates easy access to stellerator core components, but has a higher risk of incurring sealing difficulties. – Mitigation • Solicit experience from other facilities with operating cryostats. • Prototype the concepts. • Develop the cryostat in parallel with the remaining stellerator design. Make accommodations for the performance & reliability of the cryostat. • A comprehensive Failure Modes and Effects (FMEA) document that will include failures of components within the cryostat will guide the design. – Opportunity • Investigate alternative design concepts (i. e. the Alcator C-MOD design, which is a “simpler” structure that surrounds machine). SC Project Review of NCSX, April 8 -10, 2008 S. Raftopoulos page 12