OXYGEN ISOTOPE MEASUREMENT BY INSTRUMENTAL NEUTRON-ACTIVATION ANALYSIS USING REACTOR NEUTRONS - REVISITED

The oxygen isotopes O-16 and O-18 were determined using reactor instrumental neutron activation analysis by utilizing the O-16(n, p)N-16 and the O-18(n, y)O-19 reactions in the UCI 250 kw TRIGA research reactor.1 Such measurements were used to follow an exchange reaction between (H2O)-O-18 and finely ground coal. The best conditions for the determination were explored and interference reactions quantified. Single irradiation/count sequences were used to determine 30 parts per thousand of O-16 and 1 part per thousand of O-18 in a 400 mg sample of an HVA rank coal to a 25% (1sigma) precision. Reactor pulses were shown to improve these detection limits significantly. Special attention was given to correcting for the high count rates from other induced activities.