T. Kanazawa et al., CRITICAL POWER EVALUATION WITH CONSIDERATION OF DIFFERENCES IN DROPLET BEHAVIOR DUE TO SPACER SHAPE INFLUENCE, Journal of Nuclear Science and Technology, 32(4), 1995, pp. 301-312
An evaluation method for droplet deposition coefficients, correspondin
g to spacer shapes, was developed in order to predict nuclear fuel bun
dle critical power. The method is based on a three dimensional numeric
al analysis of dispersed flow around the spacer. The analysis showed t
hat coolant droplet deposition characteristics onto fuel rods differed
between grid type and ferrule type spacers, and also between fuel rod
s due to flow tabs on the upper end of the spacer band. The droplet de
position coefficient was modeled from the analysis results and adopted
into a critical power prediction code based on subchannel analysis. C
omparisons between critical powers calculated by the subchannel analys
is code and those measured with full-scale test assemblies showed good
agreement and improved prediction accuracy of the code.