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Term Definition
ultimate heat sink
The atmosphere, a body of water or ground water (or a combination of these), to which generated heat is transferred.
ultra-high-quality vacuum See vacuum pumps. Ultra high quality vacuum has a gas pressure lower than 1 µbar .
unscheduled down time The down time of the plant not according to plan.
unscheduled non-operating state When the plant or component is down according to plan for the length of the unscheduled down time due to an off-normal event.

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  Updated 13 February, 2017