NONDESTRUCTIVE DETERMINATION OF MAJOR ELEMENTS IN A LARGE-SAMPLE BY PROMPT GAMMA-RAY NEUTRON-ACTIVATION ANALYSIS

An internal monostandard method is proposed for the nondestructive det ermination of major elements in large samples by prompt gamma ray neut ron activation analysis, It successfully overcomes the problems charac teristic of large samples, such as the absorption and scattering of in cident neutrons and the absorption of emitted gamma rays. In order to make this proposed method understood theoretically an equation is pres ented and its validity for the analysis of large samples discussed, In principle, the proposed method gives relative contents iri large soli d samples, whereas it allows absolute determination for samples in sol ution form, As a demonstration for the analysis of a large solid sampl e, we analyzed an earthen vessel, and the major elements in the sample (Na, Mg, Al, Si, K, Ca, Ti, Mn, and Fe) were determined within the un certainty of 10%, except for Mn, This method was also tested for sampl es in solution form, and it was found that the absolute content of a t arget element could be obtained by constructing a calibration curve us ing several known standard solutions of different concentrations. Resi dual radioactivity after irradiation was also examined and found to be so little that the sample could be taken outside the radiation-contro lled area within a few days after the irradiation.