Technetium Immobilization Forms Literature Survey

Westsik, Joseph H.; Cantrell, Kirk J.; Serne, R. Jeffrey; Qafoku, Nikolla P.

doi:10.2172/1130666

Cited by 23 publications

(32 citation statements)

References 132 publications

(156 reference statements)

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“…Some 5 minerals, such as sodalite, can incorporate the Tc in the Tc 7+ state [12,29]. Because many minerals can only incorporate the tetravalent ion Tc 4+ [26], the Tc must undergo a reduction to be incorporated in them. The redox of Tc couples with another species within the proximity of the Tc 7+ , such as divalent iron (Fe 2+ ) shown in Equation (1), could drive the reduction of Tc 7+ to Tc 4+ [22,28,33].…”

Section: Host Phases For Tc Incorporationmentioning

confidence: 99%

“…Examples such as fougerite (green rust) [24] and sulfide-based layered double hydroxides such as potassium metal sulfides (KMS-2) [15] have been observed to 28 incorporate Tc. These are proposed as a route to remove Tc from liquid waste streams, and are able to pull Tc out of such solutions, although competition from other anions makes this method problematic [26] and low structural stability makes them less than ideal.…”

Section: Layered Double Hydroxidesmentioning

confidence: 99%

“…Magnesium phosphates, such as ceramicrete and MgKPO 4 were proposed as a Tc waste forms [112,130]. Reducing agents in the form of blast furnace slag or SnCl 2 stabilize the Tc 4+ which incorporates into the phosphate [26]. The reaction is exothermic and nearly instantaneous, and forms a monolithic solid with evenly dispersed Tc [131] Singh et al [132] formed a Mg-K-PO 4 ceramic by adding a binding mixture (MgO+KH 2 PO 4 ) to an aqueous solution of Tc with 1 M NaOH and 1 M ethylenediamine in an anoxic environment.…”

Section: Magnesium Phosphatesmentioning

confidence: 99%

“…These include spinel [18], sodalite [12], pyrochlore [19,20], perovskites [20], rutile [21], goethite [22,23], and layered double hydroxides [15,24,25]. Additionally, Tc-containing metal alloys have been studied as waste forms for immobilizing Tc [26,27].…”

mentioning

confidence: 99%

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Incorporating technetium in minerals and other solids: A review

Luksic

Riley

Schweiger

et al. 2015

Journal of Nuclear Materials

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Technetium (Tc) can be incorporated into a number of different solids including spinel, sodalite, rutile, tin dioxide, pyrochlore, perovskite, goethite, layered double hydroxides, cements, and alloys. Synthetic routes are possible for each of these phases, ranging from high-temperature ceramic sintering to ball-milling of constituent oxides. However, in practice, Tc has only been incorporated into solid materials by a limited number of the possible syntheses. A review of the diverse ways in which Tc-immobilizing materials can be made shows the wide range of options available. Special consideration is given to hypothetical application to the Hanford Tank Waste and Vitrification Plant, such as adding a Tc-bearing mineral to waste glass melter feed. A full survey of solid Tc waste forms, the common synthesis routes to those waste forms, and their potential for application to vitrification processes are presented. The use of tin dioxide or ferrite spinel precursors to reduce Tc(VII) out of solution and into a durable form are shown to be of especially high potential.

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Section: Host Phases For Tc Incorporationmentioning

confidence: 99%

Section: Layered Double Hydroxidesmentioning

confidence: 99%

Section: Magnesium Phosphatesmentioning

confidence: 99%

mentioning

confidence: 99%

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Incorporating technetium in minerals and other solids: A review

Luksic

Riley

Schweiger

et al. 2015

Journal of Nuclear Materials

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“…The immobilization of Tc, and its nonradioactive surrogate rhenium (Re), has been a subject of a vast body of literature [6][7][8][9][10][11][12][13][14]. Unfortunately, a substantial fraction of Tc escapes with the off-gas during vitrification [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Rhenium volatilization in waste glasses

Pierce

Hrma

et al. 2015

Journal of Nuclear Materials

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h i g h l i g h t sRe did not volatilize from a HLW feed until 1000°C. Re began to volatilize from LAW feeds at $600°C. The vigorous foaming and generation of gases from salts enhanced Re evaporation in LAW feeds. The HLW glass with less foaming and salts is a promising medium for Tc immobilization. a b s t r a c tWe investigated volatilization of rhenium (Re), sulfur, cesium, and iodine during the course of conversion of high-level waste melter feed to glass and compared the results for Re volatilization with those in low-activity waste borosilicate glasses. Whereas Re did not volatilize from high-level waste feed heated at 5 K min À1 until 1000°C, it began to volatilize from low-activity waste borosilicate glass feeds at $600°C, a temperature $200°C below the onset temperature of evaporation from pure KReO 4 . Below 800°C, perrhenate evaporation in low-activity waste melter feeds was enhanced by vigorous foaming and generation of gases from molten salts as they reacted with the glass-forming constituents. At high temperatures, when the glass-forming phase was consolidated, perrhenates were transported to the top surface of glass melt in bubbles, typically together with sulfates and halides. Based on the results of this study (to be considered preliminary at this stage), the high-level waste glass with less foaming and salts appears a promising medium for technetium immobilization.Published by Elsevier B.V.

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