Comparison of ASSERT-4 CHF Predictions with Measurements in 28-Element Simulated Fuel String

Abstract

The subchannel analysis code ASSERT-4 was used to model CHF experiments with a 28-element simulated fuel string carried out by Ontario Hydro at Columbia University. ASSERT was run with eleven CHF test conditions to determine dryout power using each of the five CHF models available in the code. The location of first dryout and the spreading of dryout with increasing power were also investigated. The five CHF models used in ASSERT are the Whalley mechanistic model; W-3, Bowring and Biasi correlations; and table lookup. Of these, implementation in ASSERT-4 of the Biasi correlation gives the most accurate dryout power predictions. Predictions using the table lookup method and the Whalley model are almost equally good, while those using the W-3 correlation and, especially, the Bowring correlation are inferior. In predicting dryout spreading patterns, use of the Whalley model comes the closest to adequately identifying the actual dryout location.