Analyses of single- and two-phase flow pressure drops in helical pipes using a modified RELAP5 code

Thermal fluid dynamics analyses on single- and two-phase flows in helical pipes of steam generators to be used in Generation III and IV nuclear reactors have been performed. The study concerned with experimental activities as well code simulations carried out in the framework of a collaboration between the Department of Energetics of the Polytechnic of Torino and the Department of Energy of the University of Palermo. The goal was the validation of models implemented in Relap5/Mod3.2β thermal–hydraulic advanced code to simulate the hydrodynamic behaviour of helical pipe components in spite of the one-dimensional nature of the code. It is shown that much of the experimental data obtained at several national and international research laboratories are well predicted by this modified RELAP5 code for the examined helical pipe geometries.

► Pressure drops in single and two phase flows in vertical helical pipes are examined. ► Ito single phase and modified Lockhart–Martinelli two-phase correlations were used. ► These correlations were implemented in RELAP5/MOD3.2β thermal–hydraulic code. ► The modified code was used to simulate experiments obtained at several laboratories. ► Lots of experiments performed at different helical geometries are well predicted.