Measurement of 18O/16O ratio using a fast neutron reactor

A method has been devised and proven to measure the stable isotope ratio 18O/16O for oxygen by neutron activation in a fast neutron reactor. The measurement is made non-destructively on a few grams of water with an accuracy of a few parts in 10,000. At present, measurement to this accuracy requires about 40 min with the reactor running at a power of 250 kw, but by increasing detector sensitivity the method promises to become a routine matter accomplished in less time.