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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.
D. R. Mikkelsen, H. Maassberg, M. C. Zarnstorff, C. D. Beidler, W. A. Houlberg, W. Kernbichler, H. Mynick, D. A. Spong, P. Strand, V. Tribaldos
Fusion Science and Technology | Volume 51 | Number 2 | February 2007 | Pages 166-180
Technical Paper | doi.org/10.13182/FST07-A1297
Articles are hosted by Taylor and Francis Online.
We explore whether the energy confinement and planned heating in the National Compact Stellarator Experiment (NCSX) are sufficient to test magnetohydrodynamic (MHD) stability limits, and whether the configuration is sufficiently quasi-axisymmetric to reduce the neoclassical ripple transport to low levels, thereby allowing tokamak-like transport. A zero-dimensional model with fixed profile shapes is related to global energy confinement scalings for stellarators and tokamaks, neoclassical transport properties are assessed with the DKES, NEO, and NCLASS codes, and a power balance code is used to predict temperature profiles. Reaching the NCSX goal of <> = 4% at low collisionality will require HISS-95 = 3, which is higher than the best achieved in present stellarators. However, this level of confinement is actually ~10% lower than that predicted by the ITER-97P tokamak L-mode scaling. By operating near the stellarator density limit, the required HISS-95 is reduced by 35%. The high degree of quasi-axisymmetry of the configuration and the self-consistent "ambipolar" electric field reduce the neoclassical ripple transport to a small fraction of the neoclassical axisymmetric transport. A combination of neoclassical and anomalous transport models produces pressure profile shapes that are within the range of those used to study the MHD stability of NCSX. We find that <> = 4% plasmas are "neoclassically accessible" and are compatible with large levels of anomalous transport in the plasma periphery.
