Many postulated nuclear reactor accidents result in dryout or film boiling within the nuclear core. To minimize fuel rod damage and potential rod failure, safe or lower cladding fuel temperatures must be reestablished by encour aging coolant-cladding contact. This process is commonly referred to as quenching or rewetting, and these terms are often incorrectly assumed to be synonymous. Quench and rewet are distinctly different phenomena. Quench is the rapid cooling of a hot solid surface (fuel rod cladding) resulting from enhanced heat transfer conditions and does not necessitate liquid-solid contact. Rewet, how ever, implies direct liquid-solid contact and the establish ment of a liquid-solid-vapor triple interface. The rewet temperature is normally lower than the quench temperature. Estimation of quench and rewet temperatures appears to be possible from first principles.