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Fusion Science and Technology
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Norway’s Halden reactor takes first step toward decommissioning
The government of Norway has granted the transfer of the Halden research reactor from the Institute for Energy Technology (IFE) to the state agency Norwegian Nuclear Decommissioning (NND). The 25-MWt Halden boiling water reactor operated from 1958 to 2018 and was used in the research of nuclear fuel, reactor internals, plant procedures and monitoring, and human factors.
Jeffrey A. Crowell, James P. Blanchard
Fusion Science and Technology | Volume 39 | Number 2 | March 2001 | Pages 434-438
Advanced Designs | doi.org/10.13182/FST01-A11963274
Articles are hosted by Taylor and Francis Online.
A model of the induced currents and resultant electromagnetic forces and stresses during a disruption event in the ARIES-RS tokamak design is presented. Like many other power reactor concepts, the ARIES-RS has a modular design consisting of toroidally segmented internal structures to limit disruption induced currents and facilitate maintenance. During a disruption, currents driven in these structures cross the large toroidal magnetic field producing substantial electromagnetic forces.
To consider these effects, a transient three-dimensional electromagnetic finite element model of the ARIES-RS device was created, implemented by the commercial code ANSYS. The same code was used for dynamic structural analysis.
The model includes all major components (the first wall, blankets, divertor plates, stabilizing shells, vacuum vessel, shields) electromagnetically coupled together. The magnets are assumed to remain energized during the disruption. The plasma current decay is prescribed, not coupled with the current in the structure. Halo currents and and vertical displacement events, which may produce larger forces than found in this study, are not considered.
The results illuminate important design tradeoffs. For a centered fast plasma current quench, the outboard first wall/blanket modules were found to experience the most severe loading. Current in the sidewalls generate forces that produce large torques on these structures. Supports are needed to react these loads; however, thermal stress considerations drive designs toward a first wall with a compliant support system. Thus, supports needed to reinforce against disruption loads can lower the maximum permissible heat flux on the first wall. Further, electromagnetic pressure on the first wall requires a factor of two reduction in the coolant channel width in some regions, resulting in higher pumping power.
Extension of the results to other modular tokamak designs is discussed.
Color versions of the figures are available on the world wide web at http://silver.neep.wisc.edu/disrupt or by contacting the authors.