[en] Radiation survey instruments could be used to verify the presence of radioactive material inside a container, but identification of the material would not be possible. One could imagine a very complex detector-analyzer system to analyze the radiation being emitted from a container, but it would be very large and difficult to use. At Los Alamos, a portable instrument with some limitations has been developed to identify plutonium and uranium inside a container. The instrument consists of a thin NaI crystal and an electronics package which is based on a microcomputer. The instrument uses the energy spectrum of the emitted radiation to identify the nuclear material present. The function of this instrument is to provide the user a tool for qualitative verification of nuclear materials in a container. The instrument can distinguish plutonium-239 and uranium-235 from other radioactive materials. A count rate indicator provides some measure of the quantity of material. 1 reference, 2 figures