Simulation of the concentration process in a secondary side steam generator crevice

A computer code, MULTEQ, has been developed by EPRI to predict the local water chemistry in PWR steam generator crevices. In order to know exactly how the code works and the validity of its results, a systematic study of MULTEQ has been started. It has been shown that silica initially reacts and lowers the pH but, combined with silicates, also acts as a buffer against both excessive alkalinity and excessive acidity. Calculations also predicted that cupric and cuprous copper have the same influence on crevice pH. However, they act differently on the electrochemical potential: cuprous copper tends to decrease it whereas cupric copper leads to its increase. (authors)