240Pu/239Pu and 242Pu/239Pu atom ratios of Japanese monthly atmospheric deposition samples during 1963–1966

Abstract

Global fallout plutonium isotopic ratios from the 1960s are important for the use of Pu as environmental tracers. We measured the 240 Pu/ 239 Pu and 242 Pu/ 239 Pu atomic ratios of monthly atmospheric deposition samples collected in Tokyo and Akita, Japan during March 1963 to May 1966. To our knowledge, our results represent the first data measured for actual atmospheric deposition samples collected continuously during the 1960s. Both atomic ratios increased rapidly from March 1963 to June 1963, followed by a gradual increase until September 1963. Then, both ratios declined with a half-life of approximately 5.6 months. The observed temporal changes of the ratios were likely caused by the upper-stratospheric input of nuclear debris from high-yield atmospheric nuclear weapon testing during 1961–62, followed by its downward transport to the troposphere.

Local and global trace plutonium contributions in fast breeder legacy soils

“…This illustrates the absence of a thermal neutron contribution in a fast breeder resulting in a reduced yield of 240 Pu relative to that of a thermal spectrum reactor. It is worthy of note that, while fallout from a detonation would also derive from a neutron spectrum harder than a thermal spectrum fission reactor, it would also have a much higher associated neutron flux, resulting in R 240/239 of a similar order to a thermal spectrum yield 3 , 41 , and consistent with what is observed in the average of the off-site-far data, i.e., 0.167 ± 0.005. Hence, the lower R 240/239 observed for the on-site samples in this research is consistent with the material comprising a combination of anthropogenic plutonium produced locally by a fast breeder and global fallout, on the basis that less 240 Pu is produced in a fast breeder relative to that of a thermal spectrum reactor 42 or fallout, because of the greater thermal neutron component in the former and the higher neutron flux in the latter.…”

Relativistic quantum calculations to understand the contribution of f-type atomic orbitals and chemical bonding of actinides with organic ligands

“…This is needed to understand the changes in interactions and chemical bonds, which may impact speciation and separation selectivity to different heavy elements. 1–4…”

“…These reactors are passively safe, produce less radioactive waste, offer higher fuel burn up efficiency, and do not produce industrial quantities of fissile 239 Pu. 1 Similarly, the development of vitrification using borate chemistry was inspired, in part, from evidence that a significant boron concentration exists in the brine solutions found at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico. 16,17 Actinide elements are of considerable technological importance, for example in condensed matter, as they may be high temperature superconductors or centers of lasing activity.…”

“…The latest additions, the so-called actinide elements which are the heaviest elements, are at the frontier of our current chemical and physical understanding. [1][2][3][4][5] The radioactive actinide elements residing underneath the main body of the periodic table conjure images of mushroom clouds, glowing test tubes, and superheroes awakening. While there is some truth to this view, as chemists working beyond the edge of nuclear stability, we have peered into the abyss to find elements whose realities are so complex and mystifying that we do not need to invent fanciful tales to remain a captive audience.…”

“…This is needed to understand the changes in interactions and chemical bonds, which may impact speciation and separation selectivity to different heavy elements. [1][2][3][4] Some chemical reactions can be explained by considering relativistic effects on valence electrons of heavy-atoms, e.g. the electromotive force of the cells of lead-batteries, where the relativistic effects on Pb atoms allows for the battery to work.…”