The steam generator is a most important component in the coolant loop of Pressurized Water Reactors. Although designed for a 30-40 year operating life, severe material degradation problems have occurred within the first ten years of operation. Performance and reliability evaluations are required on a continuing basis to develop solutions and design modifications to ensure reliable operation of these systems. Thermal hydraulic analysis provides basic information such as velocity and void fraction distributions within the secondary side of the steam generator needed for the evaluation of sludge deposition, bundle fouling, tube vibration, fretting, wear and fatigue. This paper presents detailed thermal hydraulic analysis of several steam generator designs, and analyzes the correlation between thermal hydraulic distributions, sludge deposition and bundle fouling using a recent model for sludge transport and deposition. The correlation between thermal hydraulic distributions and other degradation mechanisms such as circumferential cracking of tubes is also presented. The results show that there is a strong correlation between flow velocity, void fraction and sludge deposition. The calculated sludge deposit potential maps are in very good agreement with the observed results within operating steam generators.
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