ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
Latest Magazine Issues
Sep 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
September 2025
Nuclear Technology
Fusion Science and Technology
October 2025
Latest News
Empowering the next generation: ANS’s newest book focuses on careers in nuclear energy
A new career guide for the nuclear energy industry is now available: The Nuclear Empowered Workforce by Earnestine Johnson. Drawing on more than 30 years of experience across 16 nuclear facilities, Johnson offers a practical, insightful look into some of the many career paths available in commercial nuclear power. To mark the release, Johnson sat down with Nuclear News for a wide-ranging conversation about her career, her motivation for writing the book, and her advice for the next generation of nuclear professionals.
When Johnson began her career at engineering services company Stone & Webster, she entered a field still reeling from the effects of the Three Mile Island incident in 1979, nearly 15 years earlier. Her hiring cohort was the first group of new engineering graduates the company had brought on since TMI, a reflection of the industry-wide pause in nuclear construction. Her first long-term assignment—at the Millstone site in Waterford, Conn., helping resolve design issues stemming from TMI—marked the beginning of a long and varied career that spanned positions across the country.
Thomas Rummel, Konrad Riße, Michael Nagel, Thomas Mönnich, Matthias Schneider, Frank Füllenbach, Hans-Stephan Bosch, the W7-X Team
Fusion Science and Technology | Volume 75 | Number 8 | November 2019 | Pages 786-793
Technical Paper | doi.org/10.1080/15361055.2019.1629248
Articles are hosted by Taylor and Francis Online.
The Wendelstein 7-X (W7-X) experimental fusion device went into operation in 2015 after intensive commissioning. Meanwhile, the third plasma operation phase started and ran until October 2018. W7-X has three magnet systems. The superconducting magnet system creates the main magnetic field of W7-X. It consists of 70 superconducting coils, divided into seven individual circuits with ten coils each. Seven equal power supplies provide the electrical current to power the magnets. Seven magnet protection systems are also part of the system. A magnet protection system allows fast discharge of the magnets in case of severe failures, e.g., a quench that means a sudden transition from the superconducting to the normal conducting state. A special sensor system, the quench detection system, checks the status of the magnets continuously. During each of the operation phases, the superconducting magnet system is kept under cryogenic conditions at about 4 K. For that, a helium refrigerator with total power of 7 kW at 4.5 K runs steady state 24/7. The second magnet system is the trim coil system, a set of five copper coils, placed at the outer side of the machine cryostat. The coils are powered by five identical power supplies. The third magnet system is the control coil system, a set of ten copper coils, placed inside of the plasma vessel behind the divertor targets. Ten 4-quadrant power supplies power each coil separately. The power supplies can deliver bidirectional direct currents and, as per request by the experimental program, an alternating current with adjustable frequencies between 1 and 20 Hz. An operation phase of W7-X comprises about 20 weeks. During the phase, the magnet systems are normally operated 2 or 3 days per week. The superconducting magnet system is usually switched on in the morning, kept energized during the day, and ramped down in the evening. This paper analyzes the operation phases, reports on the issues during the operation, and names countermeasures and improvements performed during the breaks between the operation phases.
