Half-lives for Selected Actinides and Long-lived Radionuclides
National Nuclear Data Center, Brookhaven National Laboratory
Upton, New York 11973, USA
Long-lived actinide nuclides are of interest for their use in nuclear reactors, for nuclear reactor burnup studies in waste management, and for safeguard applications, e.g. α counting is used to determine the amount of material present. Some long-lived radionuclides are of interest for their use in determining geological ages using various dating methods, and in calculating the cosmic-ray exposure ages of meteorites. Recommended values are presented for both the total half-life and for the spontaneous fission half-life of 232-236,238U, of 236,238-242,244Pu, of 241,242m,243Am, and of 242-248,250Cm. Problems with the presentation of uncertainties are discussed. The impact of the revised 14C half-life on the carbon dating technique and various 14C ages is discussed. The possible primordial occurrence of 92Nb is now definitely ruled out. Based on examination of the 28Al half-life, the calculated value for the cosmic-ray exposure age of meteorites remains too high compared to the age calculated using other radionuclide half-life values. 204Pb, which was once thought to be radioactive, is shown to be stable.
KEYWORDS: total half-life, spontaneous-fission half-life, U, Pu, Am, Cm, 14C, 26Al, 92Nb, 204Pb