Fissile materials disposition program plutonium immobilization project baseline formulation

Ebbinghaus, B B; Armantrout, G.A.; Gray, L.W.; Herman, C.C.; Shaw, Henry F.; Konynenburg, R.A. Van

doi:10.2172/15006158

Cited by 2 publications

(1 citation statement)

References 31 publications

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“…The United States Department of Energy has determined that of 50 tons of surplus weapons plutonium and clean metal; 17 tons will be incorporated into a ceramic material and then placed in a geologic repository. (US DOE ROD 2000) The form of that ceramic material is a solid solution between four end-member oxide phases: CaHfT i207, CaUTi207, CaPuTi207, and Gd2Ti207 (Ebbinghaus 2000). The stability and behavior of plutonium in the ceramic materials as well as the phase behavior and stability of the ceramic material in the environment is not well established.…”

Section: Fundamental Thermodynamics Of Actinide-bearing Mineral Wastementioning

confidence: 99%

Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms

Gallegos¹,

Lee²,

Morales³

2003

AIP Conference Proceedings

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Section: Fundamental Thermodynamics Of Actinide-bearing Mineral Wastementioning

confidence: 99%

Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms

Gallegos¹,

Lee²,

Morales³

2003

AIP Conference Proceedings

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Chemical Stability of Zirconolite for Proliferation Resistance under Conditions Typically Required for the Leaching of Highly Refractory Uranium Minerals

Nikoloski

Gilligan

Squire

et al. 2019

Metals

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In this study, synthetic zirconolite samples with a target composition Ca0.75Ce0.25ZrTi2O7, prepared using two different methods, were used to study the stability of zirconolite for nuclear waste immobilisation. Particular focus was on plutonium, with cerium used as a substitute. The testing of destabilisation was conducted under conditions previously applied to other highly refractory uranium minerals that have been considered for safe storage of nuclear waste, brannerite and betafite. Acid (HCl, H2SO4) leaching for up to 5 h and alkaline (NaHCO₃, Na2CO3) leaching for up to 24 h was done to enable comparison with brannerite leached under the same conditions. Ferric ion was added as an oxidant. Under these conditions, the synthetic zirconolite dissolved much slower than brannerite and betafite. While the most intense conditions were observed previously to result in near complete dissolution of brannerite in under 5 h, zirconolite was not observed to undergo significant attack over this timescale. Fine zirconolite dissolved faster than the coarse material, indicating that dissolution rate is related to surface area. This data and the long term stability of zirconolite indicate that it is a good material for long-term sequestration of radioisotopes. Besides its long term durability in the disposal environment, a wasteform for fissile material immobilisation must demonstrate proliferation resistance such that the fissile elements cannot be retrieved by leaching of the wasteform. This study, in conjunction with the previous studies on brannerite and betafite leaching, strongly indicates that the addition of depleted uranium to the wasteform, to avert long term criticality events, is detrimental to proliferation resistance. Given the demonstrated durability of zirconolite, long term criticality risks in the disposal environment seem a remote possibility, which supports its selection, above brannerite or betafite, as the optimal wasteform for the disposition of nuclear waste, including of surplus plutonium.

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Fissile materials disposition program plutonium immobilization project baseline formulation

Cited by 2 publications

References 31 publications

Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms

Fundamental Thermodynamics of Actinide-Bearing Mineral Waste Forms

Chemical Stability of Zirconolite for Proliferation Resistance under Conditions Typically Required for the Leaching of Highly Refractory Uranium Minerals

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