5 of 237 Np (ca. 1.8 x 1072, 237 N/a 2381) have been reported in pitchblende by Peppard and co-workers (195}). Amecicium-241 was first fsolated from an trradiated plutonium sample by Seaborg et a}. in late 1944 (1949). Although the half-lives of c44o 247 Cm or other unidentified super heavy elements may be long enough to provide for their ({sotopic) persistence since primordial times, none have yet been measured quantitatively (Keller, op.cit). The formation of transuranium isotopes with proton or mass numbers different from those of their parent occurs primarily by nucleon capture of neutrons, deutrons and alpha particles supplied from particle accelerators or pulsed fission or fuston reactions. In the process of operating a uranium-fueled reactor, for example, isotopes of neptunium, plutonium, americium and curium are formed and can be subsequently separated from the depleted uranium fuels. The production of transuranium elements is accomplished by successive neutron capture reactions from products created from 238, or 239 Pu in nuclear detonations or in reactors. Isotopes with mass numbers as hich as 257 have been found or identified from both laboratory and thermonuclear tests (Keller, op. cit.). The mass yield of heavy isotopes from the Mike and the Barbe) and Cyclamen thermonuclear experiments decreased in atom amounts approximately logarithmically with increasing isobars from mass numbers of 239 and 242, respectively (Ofiamond et al.,1960; Keller, op.cit.). The major alpha-emitting radioisotopes of uranium, neptunium, plutonium and americium which are produced from the detonation of plutonium or uranium nuclear devices, and their mode of production as found in Lederer et at. (1967) and keller (ap.cit.), is shown in Fig. 1. From this diagram it is apparent that relating the abundance of transurantum isotopes in environmental samples to their origin from a specific radionuclide parent may be extremely difficult. This ts particularly true with respect to 23854, which can be produced by at