Physical and Radiochemical Properties of Fallout Particles

Crocker, Glenn R.; O'Connor, Joseph D.; Freiling, E.C.

doi:10.1097/00004032-196608000-00010

Cited by 30 publications

(12 citation statements)

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“…During the first few milliseconds after ignition of a near-surface nuclear test, the device components and some of the surrounding rock and soil are vaporized. In underground tests [23,24], the superheated vapor expands, forming a cavity in the surrounding rock. Small amounts of material may condense before making contact with the surfaces of the cavity, forming vitreous materials.…”

Section: Introductionmentioning

confidence: 99%

“…The cavity collapses, forming a chimney of fractured rock, and molten material collects at the bottom of the chimney, solidifying into a large mass of melt glass over several days. In surface and near-surface tests [23,24], on the other hand, a plume of vaporized device material and rock is released into the atmosphere. Melt glass can be formed in situ (directly on the surface), as well as through the melting of material pulled into the hot plume.…”

Section: Introductionmentioning

confidence: 99%

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Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Pacold

Lukens

Booth

et al. 2016

Journal of Applied Physics

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Nuclear weapons testing generates large volumes of glassy material that influence the transport of dispersed actinides in the environment and may carry information on the composition of the detonated device. We determine the oxidation state of U and Fe (which is known to buffer the oxidation state of actinide elements and to affect the redox state of groundwater) in samples of melt glass collected from three U.S. nuclear weapons tests. For selected samples, we also determine the coordination geometry of U and Fe, and we report the oxidation state of Pu from one melt glass sample. We find significant variations among the melt glass samples, and in particular, find a clear deviation in one sample from the expected buffering effect of Fe(II)/Fe(III) on the oxidation state of uranium. In the first direct measurement of Pu oxidation state in a nuclear test melt glass, we obtain a result consistent with existing literature that proposes Pu is primarily present as Pu(IV) in post-detonation material. In addition, our measurements imply that highly mobile U(VI) may be produced in significant quantities when melt glass is quenched rapidly following a nuclear detonation, though these products may remain immobile in the vitrified matrices. The observed differences in chemical state among the three samples show that redox conditions can vary dramatically across different nuclear test conditions. The local soil composition, associated device materials, and the rate of quenching are all likely to affect the final redox state of the glass. The resulting variations in glass chemistry are significant for understanding and interpreting debris chemistry, and the later environmental mobility of dispersed material.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Pacold

Lukens

Booth

et al. 2016

Journal of Applied Physics

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“…Based on autoradiography, large spherical particles (0.5-1 mm) with uniformly distribution of radionuclides and irregular several mm-sized particles with surface contamination were observed after ground-surface shots. According to Crocker et al [8], particle characteristics (size distribution, shape, colour) depended on devices and shot conditions. Pu associated with spherical particles from high altitude shots was inert in water, while Pu particles associated with debris from coral-surface bursts were relatively soluble in water.…”

Section: Marshall Island (1946-1958)mentioning

confidence: 99%

“…A variety of fused or partially fused Pu-particles and large agglomerates consisting of individual small particles differing in colour, specific activity, density and magnetic properties have been identified. The particle size distribution depended on device and shot conditions; at high altitudes spherical small-sized dense particles with activity distributed throughout the particles were obtained, while at ground surface large irregular shaped particles with lower density and specific activities were observed [8]. Leaching of gross gamma/beta activity from particles depended on device and shot conditions, matrix, particle size and type; beta emitters in airburst debris were dissolved in 0.1 M HCl.…”

Section: Marshall Island (1946-1958)mentioning

confidence: 99%

Radioactive particles released from various nuclear sources

Salbu¹,

Lind²

2005

Radioprotection

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Abstract. Radionuclides released to the environment may be present in different physico-chemical forms, ranging from ionic species to colloids, particles and fragments. Following releases during nuclear events such as nuclear weapon tests or use of depleted uranium munitions, and from nuclear accidents associated with explosions or fires, radionuclides such as uranium and plutonium are predominantly present as particles, mainly fuel particles. Similarly, radioactive particles are present in effluents from reprocessing facilities, and radioactive particles are observed in sediments in the close vicinity of radioactive waste dumped at sea. Thus, releases of radioactive particles occur far more often than earlier anticipated.Soils and sediments can act as a sink for colloids, particles and fragments, while contaminated soils and sediments may also act as a potential diffuse source, depending on particle characteristics and processes influencing particle weathering and remobilisation of associated radionuclides. To assess long-term impact from radioactive particle contamination, information on the source term is essential, i.e. activity concentrations and isotopic ratios as well as the particle size distribution, crystallographic structures and oxidation states influencing particle weathering rates and the subsequent mobilisation and biological uptake of associated radionuclides. The activity concentrations and the isotopic ratios will be source dependant, while particle characteristics will also reflect the release scenario, dispersion processes and deposition conditions. The present paper will summarise information on various nuclear sources summarise having released radioactive particles in the past.

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“…(rather than unmelted regions) indicates that radionuclides must have mixed into molten carrier material, which then quenched quickly, without significant recrystallization [7,8,9]. Aerodynamic glass objects consisting of multiple agglomerated spheroidal glasses have been observed in numerous near-surface testing environments [7].…”

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confidence: 99%

Mass Transport of Condensed Species in Aerodynamic Fallout Glass from a Near-Surface Nuclear Test

Weisz¹

2016

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In a near-surface nuclear explosion, vaporized device materials are incorporated into molten soil and other carrier materials, forming glassy fallout upon quenching. Mechanisms by which device materials mix with carrier materials have been proposed, however, the specific mechanisms and physical conditions by which soil and other carrier materials interact in the fireball, as well as the subsequent incorporation of device materials with carrier materials, are not well constrained. A surface deposition layer was observed preserved at interfaces where two aerodynamic fallout glasses agglomerated and fused. Eleven such boundaries were studied using spatially resolved analyses to better understand the vaporization and condensation behavior of species in the fireball. Using nano-scale secondary ion mass spectrometry (NanoSIMS), we identified higher concentrations of uranium from the device in 7 of the interface layers, as well as isotopic enrichment (>75% 235 U) in 9 of the interface layers. Major element analysis of the interfaces revealed the deposition layer to be chemically enriched in Fe-, Ca-and Na-bearing species and depleted in Ti-and Al-bearing species. The concentration profiles of the enriched species at the interface are characteristic of diffusion. Three of the uranium concentration profiles were fit with a modified Gaussian function, representative of 1-D diffusion from a planar source, to determine time and temperature parameters of mass transport. By using a historical model of fireball temperature to simulate the cooling rate at the interface, the temperature of deposition was estimated to be ∼2200 K, with 1σ uncertainties in excess of 140 K. The presence of Na-species in the layers at this estimated temperature of deposition is indicative of an oxygen rich fireball. The notable depletion of Al-species, a refractory oxide that is highly abundant in the soil, together with the enrichment of Ca-, Fe-, and 235 U-species, suggests an anthropogenic source of the enriched species, together with a continuous chemical fractionation process as these species condensed.

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Physical and Radiochemical Properties of Fallout Particles

Cited by 30 publications

References 1 publication

Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Chemical speciation of U, Fe, and Pu in melt glass from nuclear weapons testing

Radioactive particles released from various nuclear sources

Mass Transport of Condensed Species in Aerodynamic Fallout Glass from a Near-Surface Nuclear Test

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