Term Definition
fail-safe The behaviour of a component or system, following a failure (either internal or external). If a given failure leads directly to a safe condition, the component or system is termed fail-safe with respect to that failure.
failure modes and effects analysis A qualitative systems analysis technique in which the different failures of components are identified and the consequences of those failures on the system or plant as a whole are investigated.
FEM finite element model
FEM stress contours Finite Element Model, stress contours are a graphical way to represent the value of the stress resulting from the analysis of a component by the Finite Element Model. The stress contours are lines that cover the surface (or a section) of the model, with each line representing a "constant stress" line.
ferromagnetic inserts Plates of ferromagnetic steel included within the vacuum vessel in the shadow of the TF coils to counteract TF ripple.
FFMEA functional failure modes and effects analysis
first mirrors Components (usually of plasma diagnostics or heating systems) which reflect visible light and which are the first material surface seen by plasma radiation.
first wall FW, the interior surface of a tokamak closest to the plasma.
flat-top pulse length The duration a plasma is in quasi-steady state.
FMEA failure modes and effects analysis
fuel pellets Small slugs of frozen fuel in the 3-6 mm diameter range fired frequently (between 50 and 7 Hz respectively) into the plasma to maintain sufficient fuel density in the plasma core.
Functional Analysis A method for identifying functional requirements and analyzing performance requirements and dividing them into discrete tasks or activities. It involves the identification and decomposition of the primary system functions into sub-functions at ever increasing levels of detail.
functional FMEA FFMEA, functional failure modes and effects analysis, an extension of the FMEA method applied to functions rather than systems. It starts from a list of plant functions, identifies the ways these functions could fail and then investigates the consequences of such failures on other functions and eventually on plant safety or reliability.
functional isolation Prevention of influences from the mode of operation or failure of one circuit or system on another.
fusion The merging of two light atomic nuclei into a heavier nucleus, with a resultant loss in the combined mass. Fusion is accompanied in general by the release of energy. See also: "controlled thermonuclear fusion".
fusion performance Usually means the level of power amplification, Q, or the energy confinement time.
fusion power The power output from fusion reactions, i.e. in neutrons and alpha-particles.
fusion reactor Usually, a device harnessing fusion power to create electrical power.
FW first wall

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  Updated 13 February, 2017