[en] The presence of intergranular stress corrosion cracks (IGSCC) in thermal stressed zones in stainless steel piping and associated components is of much concern in reactor safety. The prediction of leak rates through the cracks is important in assessing the plant reliability. An analytical model has been developed to predict flow rates of initially subcooled or saturated water through these cracks. The model assumes the flow in the crack to be homogeneous and in thermal equilibrium. The crack geometry was idealized as a convergent straight slit of constant gap thickness. The fluid is assumed to enter the crack without separation. The one dimensional model accounts for the changing cross sectional area in the flow direction. The effects of wall friction, expansions/contractions and tortuosity of the actual flow path are lumped into an equivalent friction. The numerical scheme developed for the model solution has been programed into a Fortran computer code called SOURCE. A companion subroutine STEAM provides the saturated fluid properties. Inputs to SOURCE are the upstream stagnation pressure and temperature, the crack geometry specification, and the equivalent friction factor. SOURCE has been assessed against the experimental data obtained in the Battelle Columbus Laboratories (BCL) study using actual crack specimens. From a parametric study of the BCL data using SOURCE, a subcooling correction factor was developed to modify source predictions. A general methodology was developed for predicting a lumped friction factor (includes effects of bends, contractions and expansions) for use in SOURCE. Corrected SOURCE predictions using the general friction factor methodology agree well with BCL data. This method is recommended for estimating leak rates and assessing the leak-before-break criterion. 18 refs., 7 figs., 5 tabs