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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.
M.E. Friend, C.B. Baxi, S. Ishida, G. Kurita, E.E. Reis, A. Sakasai, W.P. West
Fusion Science and Technology | Volume 39 | Number 2 | March 2001 | Pages 923-929
Divertor and Plasma-Facing Components | doi.org/10.13182/FST01-A11963358
Articles are hosted by Taylor and Francis Online.
General Atomics recently completed a divertor design study for JAERI for the JT-60 Super Upgrade (JT-60SU) tokamak. JT-60SU is being designed as a superconducting device for an integrated R&D investigation of steady-state operation in a tokamak. A divertor design was developed to accommodate double-null operation for a 1000 s discharge duration at 8 MA of plasma current and 80 MW of auxiliary heating. The work reported here is an extension of a previous design study.1,2 The thermal requirements are a peak heat flux of 9 MW/m2, a maximum surface temperature of 1600°C, and a poloidal cooling flow configuration for the plasma facing components. The structural requirements are determined from both the predicted stresses due to halo currents as well as the stresses due to differential thermal expansion encountered during bakeout. The halo current loads are based on a nominal halo current of 0.19 Ip with a 2.0 toroidal peaking factor. Analysis has determined that the halo current load per centimeter of circumference is P = 2856 (1+cosθ) N/cm, where θ is the toroidal angle. The loads due to differential thermal expansion are a result of an expected 100°C temperature difference between the vacuum vessel and divertor during bakeout.
Based on the aforementioned criteria, a divertor design was developed for all three areas of the JT-60SU divertor: the inner baffle, the private flux baffle, and the outer baffle. In order to have highly reliable divertor components, flexible supports sized to accommodate the structural loads are utilized in the design rather than insulators or sliding interfaces. The plasma facing components are mounted on a structural mounting plate to form a removable and remotely-maintainable segment which is in turn mounted on the supports. For outer and private flux baffles, these structural mounting plates are joined together using a double shear joint design to form a structurally continuous ring to react the halo current loads. The plasma facing components are broken into 8° segmentation; however, the outer and private flux baffles have an alternating 8° and 16° structural segmentation which forms the double shear toroidal structural joint. The inner baffle takes advantage of its relatively short poloidal length and its proximity to the vacuum vessel to provide structural integrity. The thermal design consists of a plasma facing material of flat CFC tiles that are brazed onto a poloidally cooled copper heat sink. Adequate gaps between the baffles and wall are provided for pumping of recycled gas.
