Journal Article

PreJuSER-15787

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Survey of disruptions causes at JET

de Vries, P. C. ; Johnson, M. F. ; Alper, B. ; Buratti, P. ; Hender, T. C. ; Koslowski, H. R.FZJ* ; Riccarado, V.

2011
IAEA Vienna

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Please use a persistent id in citations: doi:10.1088/0029-5515/51/5/053018

Abstract: A survey has been carried out into the causes of all 2309 disruptions over the last decade of JET operations. The aim of this survey was to obtain a complete picture of all possible disruption causes, in order to devise better strategies to prevent or mitigate their impact. The analysis allows the effort to avoid or prevent JET disruptions to be more efficient and effective. As expected, a highly complex pattern of chain of events that led to disruptions emerged. It was found that the majority of disruptions had a technical root cause, for example due to control errors, or operator mistakes. These bring a random, non-physics, factor into the occurrence of disruptions and the disruption rate or disruptivity of a scenario may depend more on technical performance than on physics stability issues. The main root cause of JET disruptions was nevertheless due to neo-classical tearing modes that locked, closely followed in second place by disruptions due to human error. The development of more robust operational scenarios has reduced the JET disruption rate over the last decade from about 15% to below 4%. A fraction of all disruptions was caused by very fast, precursorless unpredictable events. The occurrence of these disruptions may set a lower limit of 0.4% to the disruption rate of JET. If one considers on top of that human error and all unforeseen failures of heating or control systems this lower limit may rise to 1.0% or 1.6%, respectively.

Keyword(s): J

Note: This research was funded partly by the European Communities under the contract of Association between EURATOM, FOM and CCFE. This work was carried out within the framework of the European Fusion Development Agreement. The views and opinions expressed herein do not necessarily reflect those of the European Commission.

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Contributing Institute(s):

1. Plasmaphysik (IEK-4)

Research Program(s):

1. Fusion (P13)

Appears in the scientific report 2011

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