Determination Of Thorium And Uranium In Graphite By Instrumental Neutron Activation Analysis

A method is presented for the determination of uranium (as U238) in uraniuni-loaded graphite fuel elenients by a non-destructive, direct radioactivity analysis technique. A 200-cbannel pulse-height analyzer, equipped with a 3 in. x 3 in. NaI(Tl) crystal, is used to measure the Np239 radioactivity of the neutron-irradiated samples. The amount of U238 in the test samples is deterimined quantitatively by comparing the Np239 radioactivity induced in each sample with the Np239 radioactivity induced into known standards of U238 processed under the same conditions as the test samples. The limit of detection for U238in samples of normal uranium composition for this method is about 1.0 x l0-4 ug. (auth).