Shipping cans containing product from plant runs completed in the latter half of April and in May showed, in general, definitely higher levels of radiation than had been observed previously. Likewise, containers for the transfer of the F-10-P solution from the 224 Bldg. to 231 Bldg. (during May) exhibited higher radiation levels than could be attributed to higher power levels and increased batch sizes. These higher radiation levels were indicative that some radioactive element (or elements) was present in an amount greater than previously as would be expected from the shorter cooler periods, or that decontamination of elements previously present was less complete. It was considered essential to identify the source of these radiations and the cause for their presence has been investigated. The radioactive contaminant present in the final product has been identified rather definitely as Np{sup 239} which has 2.3d half-life a 0.25 MeV gamma ray and a weak beta ray. The amount of Np has increases as a result of the brand toward shorter cooling periods and the law decontamination factor for Np in the Separation Process.