Author: Edmund Page Coomes

Publisher:

Published: 1980

Total Pages: 282

ISBN-13:

In this study a method has been demonstrated by which the departure from nucleate boiling ratio (DNBR) can be readily determined for nuclear transients through application of the COBRA-IIIC/MIT computer code. For input, boundary conditions were specified relating the time-dependent variations of core inlet coolant temperature, system pressure, core heat flux, and coolant flow. A model of the reactor core was developed for the computer code which was simple enough to be fast executing yet sufficiently detailed to provide DNBR results to within 1% of values reported in the Final Safety Analysis Report (FSAR) for the TROJAN nuclear power plant. Three transients were selected from the TROJAN FSAR for detailed analysis. The three cases involved transients of 20 seconds duration or less. Two transients, with incomplete information on the boundary conditions, resulted in minimum DNBR variations of 5% compared to the values in the FSAR. In these cases the time dependence of the calculated DNBR beyond the minimum point displayed significant deviation from the FSAR values. The third transient, with complete information, resulted in a minimum DNBR within 0.3% of the FSAR value. The time dependence of the calculated DNBR displayed no significant variation from the FSAR values.