The k0-method in INAA has been used at CENA/USP Brazil for analyzing geological and biological materials. With the acquisition of
a well-type detector, it was realized that the true-coincidence effects, originally corrected by semi-empirical procedures
with the in-house k0-software (Quantu-INAA), would affect the accuracy of results. Thus, new coincidence correction algorithms were developed,
based on a theoretical equation for obtaining the correction factors. Validation of the algorithms was performed by analysis
of plant certified reference materials.