Evaluation of N Fuels Boiling Subchannel Flow and DNB Behavior

摘要

An updated evaluation of the boiling and burnout performance of the N Reactor fuels is presented. Several new procedures and improvements for fuel analyses are described. These include the following items incorporated into the BOTHER computer program: subroutine FLOBAL which balances the flows among the boiling and nonboiling channels to equilibrate pressure drop; a new enthalpy imbalance factor for the MKIV fuel of 19.4% (95/95 basis); an updated method for calculating the two-phase pressure drop multiplier for each channel type, which includes both momentum and friction terms; and changes in the BOTHER code. The net effect of these changes is to predict DNBR limits before connecter boiling and at slightly higher flows and lower tube powers than predicted previously. (ERA citation 04:000743)