STEAM-GENERATOR SECONDARY PH DURING A STEAM-GENERATOR TUBE RUPTURE

The iodine concentration in the steam generator secondary vapor must b e determined in order to estimate the environmental consequences (i. e ., iodine source term to the environment) due to a steam generator tub e rupture (SG TR). Experimental evidence indicates that this concentra tion is sensitive to the liquid-phase pH. A thermodynamic-based calcul ational approach was used to model the pH during a design-basis SG TR. The EQUILIBRIUM code with in the Facility for Analysis of Chemical Th ermodynamics was assessed for calculation of pH by comparison with mea sured pH's in operating pressurized water reactors (PWRs). The pH was calculated for ten generic PWR designs (one Babcock & Wilcox, three Co mbustion Engineering, and six Westinghouse). The calculated pH was sho wn to be relatively insensitive to PWR design. The pH for all designs equilibrated to a value of approximately 6.5.