Non-Destructive Assay of Ce-144 in Presence of Transuranic Waste

The Ce-144 isotope has been identified as a radionuclide produced in certain Los Alamos National Laboratory plutonium waste streams and thus may need to be quantified when present in reportable quantities for shipment to the Waste Isolation Pilot Plant. The most intense gamma ray from Ce-144 was found to be the 133.53 keV peak. At this energy, there were no interfering plutonium or plutonium daughter gamma rays. Furthermore, it was determined that there were no interferences produced by Ce-144 or its progenies that could degrade the plutonium isotopic analysis. At 5 percent of the total activity per gram of plutonium, the reportable limit, the Ce-144 peak at 133.53 keV will remain above the primary plutonium peak (129.3 keV) for approximately seven years and remain quantifiable for at least twelve to thirteen years from the time the isotope was chemically separated. It is therefore concluded that Ce-144 will be quantifiable whenever it exceeds 5 percent of the total activity per gram of plutonium, and will not interfere with the non-destructive assay of plutonium isotopic compositions.