Forensic Analysis of Faulted NSTX-U Inner Poloidal Field Coil
Abstract
The failure of the NSTX-U PF1A upper coil suspended plasma operations during the project's first operational campaign after commissioning. Initial nondestructive testing and examination of the failed coil was followed by extensive nondestructive radiography. Destructive testing facilitated visual borescope/videoscope inspection through the cooling path, vacuum testing, and electrical testing of every conductor segment. One conductor cooling path visually evidenced a void through the sidewall of the cooling path in a layer-to-layer region. The identified void in the conductor cooling path was not proximal to a braze or joggle. Electrical testing indicated that the voided conductor segment was a member of a group of 14 conductor segments that evidenced low-resistance connectivity. Four braze joints and two lead segments were subjected to 400-lbf/in 2 hydrostatic pressure testing followed by helium leak testing and evidenced that there were no detectable leaks in the tested cooling path segments. The faulted region was proximal to the center of the coil pack and evidenced historical electrical pitting and molten conductor debris. Samples of the epoxy resin insulation system were extracted and analyzed with dynamic mechanical analysis and differential scanning calorimetry techniques. Epoxy resin insulation samples were subjected to immersion testing per ASTM D570. Metallurgical samples weremore »
- Publication Date:
- Research Org.:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- OSTI Identifier:
- 1463233
- Grant/Contract Number:
- AC02-09CH11466
- Resource Type:
- Accepted Manuscript
- Journal Name:
- IEEE Transactions on Plasma Science
- Additional Journal Information:
- Journal Volume: 46; Journal Issue: 7; Journal ID: ISSN 0093-3813
- Publisher:
- IEEE
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 25 ENERGY STORAGE; 42 ENGINEERING; coils; magnetic confinement; maintenance; tokamaks; conductors; testing; plasmas; coolants; toroidal magnetic fields; current measurement
Citation Formats
Petrella, Joseph R., Zatz, Irving J., Gerhardt, Stefan, Myers, Clayton E., and Boyer, Mark D. Forensic Analysis of Faulted NSTX-U Inner Poloidal Field Coil. United States: N. p., 2018.
Web. doi:10.1109/TPS.2018.2831919.
Petrella, Joseph R., Zatz, Irving J., Gerhardt, Stefan, Myers, Clayton E., & Boyer, Mark D. Forensic Analysis of Faulted NSTX-U Inner Poloidal Field Coil. United States. https://doi.org/10.1109/TPS.2018.2831919
Petrella, Joseph R., Zatz, Irving J., Gerhardt, Stefan, Myers, Clayton E., and Boyer, Mark D. Fri .
"Forensic Analysis of Faulted NSTX-U Inner Poloidal Field Coil". United States. https://doi.org/10.1109/TPS.2018.2831919. https://www.osti.gov/servlets/purl/1463233.
@article{osti_1463233,
title = {Forensic Analysis of Faulted NSTX-U Inner Poloidal Field Coil},
author = {Petrella, Joseph R. and Zatz, Irving J. and Gerhardt, Stefan and Myers, Clayton E. and Boyer, Mark D.},
abstractNote = {The failure of the NSTX-U PF1A upper coil suspended plasma operations during the project's first operational campaign after commissioning. Initial nondestructive testing and examination of the failed coil was followed by extensive nondestructive radiography. Destructive testing facilitated visual borescope/videoscope inspection through the cooling path, vacuum testing, and electrical testing of every conductor segment. One conductor cooling path visually evidenced a void through the sidewall of the cooling path in a layer-to-layer region. The identified void in the conductor cooling path was not proximal to a braze or joggle. Electrical testing indicated that the voided conductor segment was a member of a group of 14 conductor segments that evidenced low-resistance connectivity. Four braze joints and two lead segments were subjected to 400-lbf/in 2 hydrostatic pressure testing followed by helium leak testing and evidenced that there were no detectable leaks in the tested cooling path segments. The faulted region was proximal to the center of the coil pack and evidenced historical electrical pitting and molten conductor debris. Samples of the epoxy resin insulation system were extracted and analyzed with dynamic mechanical analysis and differential scanning calorimetry techniques. Epoxy resin insulation samples were subjected to immersion testing per ASTM D570. Metallurgical samples were extracted from the coil pack conductors and subjected to hardness testing and grain structure analysis. The base material testing results indicated no abnormalities. In conclusion, the coil incipient failure was determined to most likely have resulted from conductive material located between conductor and insulation layers.},
doi = {10.1109/TPS.2018.2831919},
journal = {IEEE Transactions on Plasma Science},
number = 7,
volume = 46,
place = {United States},
year = {Fri Jul 06 00:00:00 EDT 2018},
month = {Fri Jul 06 00:00:00 EDT 2018}
}
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Figures / Tables:
Figure 1: Isometric representation of the PF1A-U coil
Works referencing / citing this record:
The Stress Analysis of PF1A Lower Terminals, Leads, and Bus Bars for NSTX-U
journal, June 2019
- Fang, Jiarong; Titus, Peter; Cai, Dang
- Fusion Science and Technology, Vol. 75, Issue 8
Electrical Insulation Tape Winding and Inspection System
journal, July 2019
- Petrella, Joseph R.; D’Agostino, Michael J.; Cropper, Mark
- Fusion Science and Technology, Vol. 75, Issue 8
Figures / Tables found in this record: