Burn-up is slang for a period of fast driving, to drive fast.
Found on http://www.probertencyclopaedia.com/browse/ZBA.HTM


decrease of any fissionable nuclide concentration caused by nuclear transformation during nuclear reactor operation NOTE - This term may be applied to nuclear fuel or other materials.
Found on http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=393-15-45
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