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Modernizing I&C for operations and maintenance, one phase at a time
The two reactors at Dominion Energy’s Surry plant are among the oldest in the U.S. nuclear fleet. Yet when the plant celebrated its 50th anniversary in 2023, staff could raise a toast to the future. Surry was one of the first plants to file a subsequent license renewal (SLR) application, and in May 2021, it became official: the plant was licensed to operate for a full 80 years, extending its reactors’ lifespans into 2052 and 2053.
J. E. Rice, E. S. Marmar, P. T. Bonoli, R. S. Granetz, M. J. Greenwald, A. E. Hubbard, J. W. Hughes, I. H. Hutchinson, J. H. Irby, B. LaBombard, W. D. Lee, Y. Lin, D. Mossessian, J. A. Snipes, S. M. Wolfe, S. J. Wukitch
Fusion Science and Technology | Volume 51 | Number 3 | April 2007 | Pages 288-302
Technical Paper | Alcator C-Mod Tokamak | doi.org/10.13182/FST07-A1423
Articles are hosted by Taylor and Francis Online.
Spontaneous toroidal rotation of impurity ions has been observed in the core of Alcator C-Mod plasmas with no external momentum input. The magnitude of the rotation ranges from -60 km/s (countercurrent) in limiter L-mode discharges to +140 km/s (cocurrent) in ion cyclotron range of frequencies-heated H-mode plasmas. The core rotation in L-mode plasmas is generally countercurrent and is found to depend strongly on the magnetic topology; in near double null discharges, the core rotation changes by 25 km/s with a variation of a few millimeters in the distance between the primary and secondary separatrices. In H-mode plasmas, the rotation increments in the cocurrent direction with the toroidal rotation velocity increase proportional to the corresponding stored energy increase, normalized to the plasma current. These discharges exhibit a positive Er in the core. Immediately following the transition from L-mode into enhanced D (EDA) H-mode, the cocurrent rotation appears near the plasma edge and propagates to the center on a time scale similar to the energy confinement time but much less than the neoclassical momentum diffusion time, indicating both the role of the plasma boundary in the dynamics of the H-mode transition and the anomalous nature of momentum transport. Rotation velocity profiles are flat in EDA H-mode plasmas and centrally peaked for edge-localized mode-free H-modes, demonstrating the effects of an inward momentum pinch. In EDA H-mode discharges that develop internal transport barriers, the core toroidal rotation inside the barrier foot is observed to drop on a time scale similar to the core pressure profile peaking (hundreds of milliseconds), indicating a negative Er well in the core region.
