Application of portland cement-based materials to radioactive waste immobilization

Atkins, M.; Glasser, F. P.

doi:10.1016/0956-053x(92)90044-j

Cited by 230 publications

(151 citation statements)

References 12 publications

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“…The results in Figure 2 are consistent with Atkins and Glasser (1992) who demonstrate that the creation of a reducing environment in slag-containing grout (and therefore Tc removal from the aqueous environment) occurs over a period of months. They showed that the rate reducing grout creates a reducing environment depends on the amount of slag in the formula.…”

Section: Resultssupporting

confidence: 80%

Long-Term Technetium Interactions With Reducing Cementitious Materials

Kaplan¹,

Lilley²,

Almond³

et al. 2011

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Revision 0 can oxidize technetium in a portland cement or saltstone-like monolith. The shrinking core model used in the saltstone performance assessment describes the existence of an oxidized outer layer of concrete surrounding a shrinking core of reducing intact saltstone. A sharp boundary between the two zones moves slowly inward, resulting in oxidation of Tc(IV). This work largely reinforced our conceptual model of the shrinking core model, but more importantly provided clarity regarding process kinetics, mechanisms, and input values for future detailed modeling. The shrinking core model in itself is devoid of geochemical mechanisms. This study provided more geochemical detail to this conceptual numerical model. vii SRNL-STI-2010-00668 Revision 0

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Section: Resultssupporting

confidence: 80%

Long-Term Technetium Interactions With Reducing Cementitious Materials

Kaplan¹,

Lilley²,

Almond³

et al. 2011

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“…The measured specific surface area, bulk density, and total mass of grout material loaded into the flow cell are 32.9 m 2 /g, 1.92 g/cm 3 , and 242 g, respectively. The calculated volume and initial porosity of the grout material in the column are 126 cm 3 and 52 percent.…”

Section: Resultsmentioning

confidence: 99%

“…Studies have shown that grouted systems containing blast furnace slag are effective in mitigating the release of Tc-99 [1][2]. Hydration of the blast furnace slag in the grout mixture releases sulfide species into the pore fluid, predominantly as S 2-, which can impose a strongly reducing redox potential (Eh) on the system [3] and can react with technetium to form relatively insoluble Tc 3 S 10 [4] or Tc 2 S 7 [5]. In cementitious systems, U(IV) is less soluble than U(VI) [6] and Se(IV) (as the selenite ion, SeO 3 2 ) is less mobile than Se(VI) (as the selenate ion, SeO 4 2 ) [7].…”

Section: Introductionmentioning

confidence: 99%

Experimental Study of Contaminant Release from Reducing Grout

Pabalan

Alexander

Waiting

et al. 2013

EPJ Web of Conferences

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Abstract.A column experiment was conducted to study the release behavior of technetium, uranium, and selenium initially sequestered in reducing grout similar in composition to Savannah River Site (SRS) saltstone, a cementitious waste form made by mixing salt solution from SRS liquid waste storage tanks with a dry mix containing blast furnace slag, fly ash, and Portland cement. The data suggest that uranium was retained in the grout possibly as a CaUO 4 phase, whereas most of the selenium was released. Technetium release initially was relatively constant, and then increased significantly after 26 pore volumes. The increase in technetium release was slightly delayed relative to the observed Eh increase. The system Eh-pH started under conditions in which technetium solubility is low, constrained by Tc 3 O 4 solubility, but eventually transitioned into the stability field of the pertechnetate ion. The delay in technetium release relative to the Eh increase was possibly due to slow oxidation of technetium at depth within the grout particles, which in turn was likely controlled by O 2 diffusion into the particles. In contrast to technetium and uranium, selenium release was not solubility limited and selenium likely was present in the pore solution initially as a HSe  species.

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“…This is due to the fact that grout is a chemically and physically evolving system with solubility limiting metal-mineral phases, metal mobility, corrosion phases and mineral components all changing over time. For example, the presence of quartz (SiO 2 ), a primary component of grout, was neglected in grout behaviour studies by Glasser [9] and Atkins [10], when studying the Ca-UO 3 -H 2 O system, even though valuable data was collected regarding the formation of sodium, calcium and uranium mineral phases. The main issue with creating analogous in-situ corrosion experiments is the required time frame to mimic current waste forms which have been evolving for up to 60 years.…”

Section: Current Monitoring Methodsmentioning

confidence: 99%

Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

Jones

Brenner

Stitt

et al. 2016

Journal of Hazardous Materials

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A small scale sample nuclear waste package, consisting of a 28mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an x-ray source driven by a highpower laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating x-rays (with energy >500keV), with a source size of <0.5mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30cm 2 scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the x-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned.

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Application of portland cement-based materials to radioactive waste immobilization

Cited by 230 publications

References 12 publications

Long-Term Technetium Interactions With Reducing Cementitious Materials

Long-Term Technetium Interactions With Reducing Cementitious Materials

Experimental Study of Contaminant Release from Reducing Grout

Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages

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