Plutonium isotopic measurements by gamma-ray spectroscopy

A method is reported for analysis of isotopic and total plutonium by detecting and analyzing gamma rays emitted by the sample. A computerized prototype-system was developed and is now being routinely used at the Savannah River Plant for the nondestructive assay of solution samples. The analyses for 238Pu, 239Pu, 240Pu, 241Pu, and for 241Am, when it is present, can be made in counting times as short as 10 to 15 minutes under optimum conditions. Comparison of isotopic ratio values with mass spectrometry generally shows agreement within 0.1 percent for 239Pu and about 1 percent for 240Pu and 241Pu. Some preliminary isotopic measurements on solids are also discussed. (U.S.)