Particle deposition and fouling in PWR steam generators

Commercial PWR steam generators have experienced reliability problems within the first decade of operation associated with material degradation, one of the causes of which is particle deposition and tube fouling. As a result steam generators often require costly outages for inspection and cleaning of fouling deposits. Knowledge of locations where sludge has accumulated in the steam generator can aid in planning and targeting locations for cleaning and removal of deposits. A particulate deposition model has been developed and implemented in the three dimensional thermal hydraulics computer code, ATHOS3 lo calculate sludge and fouling regions within the steam generators during operation. This transient particle deposition model uses the thermal hydraulic field calculated by the ATHOS3 code, and the concentration of magnetite particles entering the steam generator to calculate the particle distributions and deposition on vertical and horizontal surfaces within the steam generator. Results of some simulations of operating steam generator designs are presented in this paper. These results show that preferred regions for deposition include hot side upper bundle and a kidney shaped region on top of the tube sheet.