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Fusion Science and Technology
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ANS hosts webinar on criticality safety standards
A diagram depicting the NRC’s regulatory structure for nuclear criticality safety. (Image: Oak Ridge National Laboratory)
The American Nuclear Society’s Risk-informed, Performance-based Principles and Policy Committee (RP3C) held another presentation in its monthly Community of Practice (CoP) series last month. RP3C chair Steven Krahn opened the meeting with brief introductory remarks about the importance of risk-informed, performance based (RIPB) decision-making and the need for new approaches to nuclear design that go beyond conventional and deterministic methods.
A. A. Belokurov, L. G. Askinazi, V. K. Gusev, E. O. Kiselev, G. S. Kurskiev, A. V. Petrov, Yu. V. Petrov, A. M. Ponomarenko, S. Yu. Tolstyakov, A. Yu. Yashin
Fusion Science and Technology | Volume 81 | Number 2 | February 2025 | Pages 109-117
Research Article | doi.org/10.1080/15361055.2024.2362530
Articles are hosted by Taylor and Francis Online.
The intermediate mode between the ohmic, or low confinement (L-mode), and the increased confinement (H-mode) regimes, or the so called I-phase, which is characterized by the existence of zonal flows in the form of limit cycle oscillations (LCOs), was observed on the Globus-M tokamak. Depending on the LCO frequency, the I-phase resulted in either a transition to H-mode or back to L-mode. The possibility of L-I-H transition initiation induced by LCOs and the effect of LCO frequency were studied by means of numerical modeling of the density profile evolution, taking into account turbulence suppression by the inhomogeneous radial electric field. The modeling results show that lower LCO frequency could be a factor facilitating the L-H transition, whereas higher frequency LCOs are more likely to cause the backward transition to L-mode. The results are in qualitative agreement with the results of the studies of geodesic acoustic mode (GAM)–initiated L-H transition in the TUMAN-3M tokamak, where a lower GAM frequency was found to be beneficial for L-H transition initiation.