Survey of disruption causes at JET

TitleSurvey of disruption causes at JET
Publication TypeJournal Article
Year of Publication2011
AuthorsP.C de Vries, M.F Johnson, B. Alper, P. Buratti, T.C Hender, H.R Koslowski, V. Riccardo
JournalNuclear Fusion
Volume51
Issue5
Pagination053018
Date PublishedMay
Type of ArticleArticle
ISBN Number0029-5515
KeywordsDENSITY LIMITS, DISCHARGES, MHD STABILITY, OPTIMIZED SHEAR, PLASMAS, TEARING MODES, TEXTOR-94, TOKAMAKS
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.

DOI10.1088/0029-5515/51/5/053018
Division

FP

Department

PDG

PID

23142528e953c899f771273317fbc863

Alternate TitleNucl. Fusion

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