Effect of CANDU Bundle-Geometry Variation on Dryout Power

Dryout powers have been evaluated at selected inlet-flow conditions for two proposed designs of CANDU® bundles and compared to those of the 37-element and CANFLEX® bundles. These proposed designs consist of a large centre element (18 mm for one design and 20 mm for the other) and three rings of elements of 11.5 mm in outer diameter. The critical heat flux for each bundle design has been predicted using the correlation derived with Freon data obtained from the corresponding full-scale bundle test. An improvement in dryout power has been shown for the proposed design having a 20-mm centre element with a radial power profile corresponding to the natural-uranium fuel as compared to other bundles, particularly the natural-uranium 37-element bundle, with a symmetric cosine axial power profile. The dryout power improvement is further enhanced for the upstream-skewed axial power profile.Copyright © 2008 by ASME