Applications of neutron activation analysis in determination of natural and man-made radionuclides, including PA-231

Neutron activation analysis (NAA), being essentially an isotopic and not an elemental method of analysis, is capable of determining a number of import ant radionuclides of radioecological interest by transformation into anothe r, more easily quantifiable radionuclide. The nuclear characteristics which favour this technique may be summarized in an advantage factor relative to radiometric analysis of the original radioanalyte. Well known or:hardly kn own examples include U-235, U-238, Th-232, Th-230, I-129, Tc-99, Np-237 and Pa-231; a number of these are discussed and illustrated in analysis of rea l samples of environmental and biological origin. In particular, determinat ion of Pa-231 by RNAA was performed using both postirradiation and presepar ation methods. Application of INAA to enable the use of U-238 and Th-232, a s endogenous (internal) radiotracers in alpha spectrometric analyses of ura nium and thorium radioisotopes in radioecological studies is described, als o allowing independent data sets to be obtained for quality control.