Determination of Np-237 Concentration in Plutonium Solutions with the Use of a Portable U-Pu Inspector Instrument

The Np-237 concentration in three plutonium test solutions has been determined by gamma spectrometry with the MGA [1] program incorporated into the Canberra U-Pu Inspector system. These three test solutions were encapsulated in glass ampules in 1992 in connection with a Laboratory Intercomparison project [2]. At the time the Institute of Inorganic Materials determined the Np-237 concentration in these test solutions using isotope dilution gamma spectrometry (Laboratory 3 in reference [2]). The results of isotope dilution gamma spectrometry and common gamma spectrometry were in good agreement with the known value of Np-237, while the laboratories that used MGA for their analysis method at the time showed a bias in their results. In this work, we demonstrate significantly improved results with the latest version of MGA that is now incorporated into the Canberra U-Pu Inspector originally prepared by mixing plutonium and neptunium system.