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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.
Kazuyoshi Hada, Kazunobu Nagasaki, Kai Masuda, Shinji Kobayashi, Shunsuke Ide, Akihiko Isayama, Ken Kajiwara
Fusion Science and Technology | Volume 67 | Number 4 | May 2015 | Pages 693-704
Technical Paper | doi.org/10.13182/FST14-811
Articles are hosted by Taylor and Francis Online.
By using a one-dimensional model, we analyze plasma start-up assisted by second-harmonic extraordinary-mode electron cyclotron (EC) resonance heating (ECRH). The model leads to energy transport equations for electrons and ions, particle transport equations for electrons and hydrogen atoms, and a toroidal current equation. These equations are solved for a cylindrically symmetrical plasma; that is, a torus straightened to a cylinder with a circular cross section and on-axis ECRH power absorption. The calculation indicates that ECRH has a threshold power for plasma start-up in JT-60SA. For example, approximately 1 MW of ECRH power is required for plasma start-up for an initial hydrogen atom density nH(t=0) = 3.0 × 1018 m-3, an error field Berr = 1 mT, carbon and oxygen impurity fractions nc/ne = no/ne = 0.1%, and an EC beam radius of approximately 5 cm. This estimated ECRH power is less than the planned power and increases sublinearly with the initial hydrogen atom density. The threshold power depends weakly on the error field and carbon impurity concentration. This is especially prominent for plasma start-up with a low initial hydrogen atom density. This result implies that suppressing the error field and carbon impurity density is helpful for reliable plasma start-up.