Nondestructive assay of the fissile content in FBTR fuel pins

A rapid method for nondestructive assay of Fast Breeder Test Reactor (FBTR) fuel pins has been demonstrated using the two-step process of high-resolution gamma-ray spectrometry for isotopic composition measurement followed by neutron well coincidence counting for total plutonium content. The data have been compared with those obtained from Thermal Ionization Mass Spectrometry (TIMS) and potentiometry. The fissile isotopic ratio 239Pu/241Pu measured by gamma-ray spectrometry was found to be close to the TIMS values within 1%. The total plutonium content of FBTR fuel pins measured by neutron counting was found to be in agreement with the estimated values obtained using potentiometry within 1%.