Application of k0-based internal mono standard instrumental neutron activation analysis method method for composition analysis of stainless steel clad sample

The k₀-based internal mono standard instrumental neutron activation analysis (INAA) method was used for the composition analysis of some irregular shape stainless steel (SS) samples of type SS 316M, which is used as fuel cladding in Indian fast breeder test reactor (FBTR). The method utilizes in situ relative detection efficiency using γ-rays of the activation products present in the sample for overcoming γ-ray self-attenuation. Samples were neutron activated using the thermal column as well as the core position of the reactor and the assay of radioactivity was carried out by high-resolution gamma ray spectrometry. The elements determined were Fe, Cr, Ni, Mo, Mn, Co, Cu, As and W. Since all the major elements (Fe, Cr, Ni, Mo and Mn) were amenable to NAA, the relative elemental concentrations with respect to Fe, obtained by this method, were converted to their absolute values by mass balance. The results were compared with specified compositions and found to be satisfactory. In order to validate these results obtained by the standard-less approach, sub samples of SS 316M in solution forms were analyzed by prevalent relative and k₀ methods of INAA, and results were found to be in good agreement. The accuracy of the internal mono standard INAA method has been evaluated by analyzing an alloy steel certified reference material, CRM 225/1 of British Chemical Standards (BCS).