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Fusion Science and Technology
Latest News
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.
Alan L. Hoffman, Larry N. Carey, Edward A. Crawford, Dennis G. Harding, Terence E. DeHart, Kenneth F. McDonald, John L. McNeil, Richard D. Milroy, John T. Slough, Ricardo Maqueda, Glen A. Wurden&
Fusion Science and Technology | Volume 23 | Number 2 | March 1993 | Pages 185-207
Technical Paper | Experimental Device | doi.org/10.13182/FST93-A30147
Articles are hosted by Taylor and Francis Online.
The Large-s Experiment (LSX) was built to study the formation and equilibrium properties of field-reversed configurations (FRCs) as the scale size increases. The dynamic, field-reversed theta-pinch method of FRC creation produces axial and azimuthal deformations and makes formation difficult, especially in large devices with large s (number of internal gyroradii) where it is difficult to achieve initial plasma uniformity. However, with the proper technique, these formation distortions can be minimized and are then observed to decay with time. This suggests that the basic stability and robustness of FRCs formed, and in some cases translated, in smaller devices may also characterize larger FRCs. Elaborate formation controls were included on LSX to provide the initial uniformity and symmetry necessary to minimize formation disturbances, and stable FRCs could be formed up to the design goal ofs = 8. For s ≤ 4, the formation distortions decayed away completely, resulting in symmetric equilibrium FRCs with record confinement times up to 0.5 ms, agreeing with previous empirical scaling laws (τ α sR). Above s = 4, reasonably long-lived (up to 0.3 ms) configurations could still be formed, but the initial formation distortions were so large that they never completely decayed away, and the equilibrium confinement was degraded from the empirical expectations. The LSX was only operational for 1 yr, and it is not known whether s = 4 represents a fundamental limit for good confinement in simple (no ion beam stabilization) FRCs or whether it simply reflects a limit of present formation technology. Ideally, s could be increased through flux buildup from neutral beams, thus avoiding dynamic formation disturbances at high s. Since the addition of kinetic or beam ions will probably be desirable for heating, sustainment, and further stabilization of magnetohydrodynamic modes at reactor-levels values, neutral beam injection is the next logical step in FRC development. Efficient ion current buildup requires low-density and high-temperature target plasmas, and low fill pressure (sub-mTorr) formation methods to produce such FRCs were also developed, for the first time, on LSX.