ASSESSMENT OF A TUBE-BASED BUNDLE CHF PREDICTION METHOD USING A SUBCHANNEL CODE

At the conceptual design stage for advanced water-cooled reactors (AWC Rs), a general critical heat Aux (CHF) prediction method with a wide a pplicable range and reasonable accuracy is essential to the thermal-hy draulic design and safety analysis. A basic idea for general CHF predi ction is to utilize the tube-based CHF models covering wide applicable ranges with the help of supplementary terms for bundle effects. In th is study, feasibility assessments have been performed with the bundle CHF data relevant ro pressurized water reactors. A subchannel analysis is adopted in order to be able to consider the geometrical variations properly even in unrested fuel bundle geometries. As a result, a CHF look-up table method (i.e., the use or a round tube CHF table with app ropriate bundle effect factors) turns out to be a promising Way to ful fill the needs in many aspects among some selected correlations and th eoretical models. Though improvements of the supplementary factors, es pecially for the cold wall and the bundle heated length effects, are d esirable to make better predictions, the tube-based bundle CHF predict ion method clearly shows a potential as a general CHF predictor. (C) 1 998 Published by Elsevier Science Ltd. All rights reserved.