Burnout heat fluxes for NPR tube-in-tube fuel elements

A common criterion for nuclear reactors is that operating conditions should always be less severe than those which could produce boiling burnout and cause extensive damage to fuel elements. The present knowledge of boiling heat transfer is not sufficient to allow predictions of boiling burnout conditions by theoretical means. Even the use of equations representing correlations of experimental data is not sufficiently accurate for a reactor design different from the configurations used in obtaining the data. Therefore, experiments were performed in the 189-D Heat Transfer Laboratory to define the boiling burnout conditions for the NPR. Results of these experiments are presented. (auth)