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Getting back to yes: A local perspective on decommissioning, restart, and responsibility
For 45 years, Duane Arnold Energy Center operated in Linn County, Ia., near the town of Palo and just northwest of Cedar Rapids. The facility, owned by NextEra Energy, was the only nuclear power plant in the state.
In August 2020, a historic derecho swept across eastern Iowa with winds approaching 140 miles per hour. Damage to the plant’s cooling towers accelerated a shutdown that had already been planned, and the facility entered decommissioning soon after, with its fuel removed in October of that year. Iowa’s only nuclear plant had gone off line.
Today the national energy landscape looks very different than it did just six short years ago. Electricity demand is rising rapidly as data centers, artificial intelligence infrastructure, advanced manufacturing, and electrification expand across the country. Reliable, carbon-free baseload power has become increasingly valuable. In that context, Linn County has approved the rezoning necessary to support the recommissioning and restart of Duane Arnold and is actively supporting NextEra’s efforts to secure the remaining state and federal approvals.
Evan Kallenberg, Brendan Crowley, John T. Scoville, Florian M. Laggner, Arthur Mazzeo, Keanu J. Ammons, Md. Sazzad Hossain, Liam King, Amanda M. Lietz, Steven C. Shannon
Fusion Science and Technology | Volume 82 | Number 1 | January-February 2026 | Pages 92-105
Research Article | doi.org/10.1080/15361055.2025.2515323
Articles are hosted by Taylor and Francis Online.
The DIII-D National Fusion Facility aims to increase the auxiliary heating power for the tokamak by upgrading the neutral beam injection (NBI) system. In collaboration with North Carolina State University, the conventional arc-and-filament NBI ion sources will be converted to inductively coupled plasma (ICP) sources that utilize radiofrequency (RF) coupling to maximize reliability for high-power operation. In support of this initiative, a full-scale test device, Superior Radiofrequency Ion Source Experiment (SupRISE,) is currently under construction at the DIII-D facility.
In preparation for the construction of a full-scale prototype that can be installed on the DIII-D NBI system, experiments on SupRISE have been conducted to determine the optimal RF frequency for high-power coupling, the Faraday shield slit configuration, and the ICP chamber length. SupRISE is comprised of an approximately 30 × 70 cm quartz dielectric vessel with an internal Faraday shield enclosed in a secondary vacuum chamber to ensure structural stability of the dielectric. Actively cooled front and back plates are designed to reduce the thermal stresses on the plasma-facing components and mate with the existing accelerator used by the NBI system at DIII-D.
A total of 50 kW of RF power will be coupled to the plasma through the quartz over a variable frequency range of 4 to 8 MHz to sustain a plasma density of ~1018 m for a 10-s ON, 210-s OFF duty cycle. Various modeling efforts have been employed to simulate the thermal and stress profiles over the primary components of the SupRISE device, as well as the inductance behavior of the RF antenna.
These simulation results and the final design for SupRISE are presented. An additional reduced-scale predecessor ICP source (called RISE) has been used to develop a predictive match model that will be applied to frequency optimization studies on SupRISE. The outcomes of this research and complementary efforts at North Carolina State University are essential for the incorporation of ICP NBI positive ion sources at the DIII-D facility.
