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Argonne’s METL gears up to test more sodium fast reactor components
Argonne National Laboratory has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop), the Department of Energy announced April 23. The upgrade is the first of its kind in the United States in more than 30 years, according to the DOE, and will help test components and operations for the sodium-cooled fast reactors being developed now.
Mitsushi Abe,* Akira Doi, Kazuhiro Takeuchi, Michio Otsuka, Shigeyoshi Kinoshita, Satoshi Nishio, Masayoshi Sugihara, Ryuji Yoshino
Fusion Science and Technology | Volume 32 | Number 4 | December 1997 | Pages 545-560
Technical Paper | Special Section: Plasma Control Issues for Tokamaks / Plasma Engineering | doi.org/10.13182/FST97-A19904
Articles are hosted by Taylor and Francis Online.
Tokamak startup characteristics with a low-loop-resistance vacuum vessel were studied in the HT-2, which is a tokamak with a major radius of 41 cm, a minor radius of 11 cm, and a plasma current of IP < 55 kA. Precise poloidal magnetic field control is possible using independently and multivariably controlled poloidal field coils. The vacuum vessel loop resistance Ωv was originally high (14 mΩ), but it was modified to be able to operate with a low value (0.3 mΩ). The latter is approximately one-tenth of the plasma resistance (2.2 mΩ) at breakdown (Te = 10 eV). With Ωv = 0.3 mΩ, the magnetic field induced by the eddy current is large, and it disturbs the breakdown. However, careful compensation of the poloidal field makes a well-controlled ohmic startup possible. Other results are as follows: very little difference in the consumed ohmically heated flux was observed between discharges with low and high loop resistances; well-controlled startup was obtained with a very low loop voltage of 2.5 V, which corresponded to the 1 V/m electric field; the breakdown condition is well described by the electron avalanche model. It is concluded that low Ωv is applicable to a tokamak design, as long as the poloidal magnetic field is well controlled even during the breakdown phase.