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Fusion Science and Technology
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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.
R. Fischer, L. Giannone, J. Illerhaus, P. J. McCarthy, R. M. McDermott, ASDEX Upgrade Team
Fusion Science and Technology | Volume 76 | Number 8 | November 2020 | Pages 879-893
Technical Paper | doi.org/10.1080/15361055.2020.1820794
Articles are hosted by Taylor and Francis Online.
The results of transport modeling codes, e.g., GENE for the plasma core or SOLPS-ITER for the plasma edge, depend critically on reliable profile and equilibrium estimates. The propagation of uncertainties (UP) of input quantities to the results of modeling codes, e.g., power and particle exhaust and plasma stability, is frequently neglected because of the costs of running the codes as well as because of the missing uncertainty quantification of input quantities. The situation becomes even more cumbersome if profile gradients and their uncertainties are of major concern for transport analyses.
Two different techniques are presented to estimate profiles, profile gradients, their uncertainties, and candidate profiles for UP in modeling codes. Markov Chain Monte Carlo sampling of the posterior probability density of an integrated data analysis approach is applied to estimate electron density and temperature profiles. Nonstationary Gaussian process regression is applied to estimate ion temperature and angular velocity profiles. Both methods provide in a natural way profile gradients, profile logarithmic gradients, and their uncertainties.
Modeling codes benefit also from reliable equilibrium reconstructions and quantification of the uncertainty of various equilibrium parameters. For the analysis of diagnostics data, the position and uncertainty of flux surfaces as well as of the magnetic axis are important. For plasma transport and stability codes, the estimation of uncertainties of current and q-profiles is presented. For plasma edge codes the position of the separatrix contour and its uncertainty at various poloidal positions is of primary interest especially if steep profile gradients are present. Examples of uncertainties and their sources in magnetic scalar quantities, profiles, and separatrix contours are shown.