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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Deep Space: The new frontier of radiation controls
In commercial nuclear power, there has always been a deliberate tension between the regulator and the utility owner. The regulator fundamentally exists to protect the worker, and the utility, to make a profit. It is a win-win balance.
From the U.S. nuclear industry has emerged a brilliantly successful occupational nuclear safety record—largely the result of an ALARA (as low as reasonably achievable) process that has driven exposure rates down to what only a decade ago would have been considered unthinkable. In the U.S. nuclear industry, the system has accomplished an excellent, nearly seamless process that succeeds to the benefit of both employee and utility owner.
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.