Zircon: A host-phase for the disposal of weapons plutonium

Abstract

Zircon, ZrSiO4, is a well-characterized, naturally occurring phase that is extremely durable. Zircon has been synthesized with Pu-concentrations up to 10 wt. % and radiation-damage effects studied to saturation doses of nearly 0.8 displacements per atom. We propose that zircon be used as a waste form for the disposal of the more than 100 metric tons of plutonium that will result from the dismantling of nuclear weapons. There are already several demonstrated processing technologies, of which hot pressing offers the most potential. This highly durable material, even under hydrothermal conditions, with its high waste loading and smaller volume allows deep, permanent disposal of the weapons plutonium in geologic environments in which the borosilicate waste-form glass would not be stable.

Ion irradiation-induced amorphization and nano-crystal formation in garnets

“…The radiation susceptibility of zircon is well studied, because the Zr in zircon can be replaced by Pu [2,[21][22][23]. Zircon shows a two-step dependence of critical dose for amorphization as a function of temperature under 1.5 MeV Kr þ irradiation; below 300 K and above 475 K [24].…”

Chemical and Ceramic Methods Toward Safe Storage of Actinides

“…Although it would seem that monazite should be one of the very best candidate radwaste hosts for a thorough ceramic study as detailed herein, we should further compare it with zircon, ZrSiO 4 , the other natural host phase for actinide elements, which is comparably stable with monazite in a variety of geological environments (Silver, 1982, Ewing, 1995. Zircon does not self-anneal at low temperatures so is often found in nature to be metamict; the higher temperature annealing of natural radiation damage has been extensively studied by optical, X-ray and TEM techniques.…”

Iron Doped-ZrSiO4: Structural, Microstructural and Vibrational Characterization

“…Furthermore, a large variety of transition and/or rare-earth metal cations can be incorporated into the host lattice. It is for this reason that zircon is often considered as a natural host material for the storage of radioactive waste material [8][9][10][11] . ZrSiO 4 is also considered as a promising alternative to silicon oxide as the gate dielectric material in metal-oxide semiconductor devices because of its high permittivity 12 .…”

“…In the last decade, several authors have studied different topics referred to the structural and chemical characteristics of Fe-ZrSiO 4 [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] . The mechanism of formation, the chemical state, and location of Fe cation in the zircon structure, the actual presence of segregated hematite and dissociation of zircon [25][26][27] have been considered as main topics.…”