The kay-zero Epithermal Neutron Activation Analysis technique is a physical technique applied for the absolute measurement of elemental concentration present in almost all sort of samples. The sample specification ranges are liquid, biological and geological. Among the geological samples we have archaeological samples in which determination of the terrestrial elemental concentration of Th, U and K present lead to dating and a revealed of historical facts. In other to improve the scope of Nigeria Research Reactor-1, 0.1 mm cadmium lined was installed in one of the ten irradiation channels. This was aimed in shielding almost completely the thermal neutrons. A critical analysis of the neutron stability after the installation was performed. In terms of quality control, other channels including the modified large outer channel were re-characterized and results compared before and after the installtion. A further application of the modified channel was used to evaluate the concentration of Th, U and K along with some rare earth elements in IAEA lake sediment SL-1, NIST-Coal fly ash 1633b and some archaeological matrices within five days. The dose rate of the matrices used were determined