Vitrification of an intermediate level Magnox sludge waste

Tan, Shengheng; Kirk, Nicholas; Marshall, Martyn; McGann, Owen J.; Hand, Russell J.

doi:10.1016/j.jnucmat.2019.01.007

Cited by 17 publications

(5 citation statements)

References 22 publications

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“…Vitrification is primarily used for HLW immobilisation, but it recently showed potential for ILW immobilisation as well. 80,81 In this process, glass frit is melted with nuclear waste, and at the end of the vitrification process, radionuclides are chemically immobilized within the glass network. 2 Problematic elements for the vitrification process include I, Xe, Kr, Cs, and especially Tc, because they are volatile at high temperatures.…”

Section: Vitrificationmentioning

confidence: 99%

Nuclear Waste Management

Cetina

2024

Kem. ind. (Online)

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Nuclear energy production generates nuclear waste. Nuclear and radioactive waste, especially high level waste (HLW) and intermediate level waste (ILW), require special long-term safe management solutions. One part of the solution involves recycling through reprocessing of spent nuclear fuel. Recycling reduces the volume of nuclear waste and allows for the reuse of some of its components. This can be achieved through methods such as adsorption, ion exchange, coagulation, flotation, filtration, chemical precipitation, reverse osmosis, and solvent extraction, like the PUREX process. Another possible future solution involves partitioning and transmutation technology, which can reduce the production of nuclear waste. The best long-term solution is the immobilisation of HLW and ILW in a solid matrix. Materials used for this purpose include glasses, cements, bitumen, geopolymers, concrete, and ceramics as a promising material. While cementation is still the most commonly used immobilisation method due to its low cost and simplicity, vitrification is a more permanent long-term solution. Deep geological disposal in combination with vitrification and a robust multi-barrier system is considered the most acceptable solution for safe nuclear waste isolation. This review provides insight into the mostly commonly used and promising immobilisation materials, as well as the most effective methods and technologies currently in use and under development for the management of HLW and ILW in nuclear waste management.

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Section: Vitrificationmentioning

confidence: 99%

Nuclear Waste Management

Cetina

2024

Kem. ind. (Online)

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“…17,18 This is especially true for the vitrification of low-activity waste, which is a technologically much less mature process, because LAW was historically treated using other technologies, such as cementation, bituminization, or compaction and containerization. [19][20][21] Over the past decade, our understanding of the melting process was significantly improved by measuring and analyzing a vast volume of data on feed responses to heating in terms of chemical reactions and phase transitions that occur as temperature increases. 7,[22][23][24][25][26][27][28][29][30][31] Despite this significant research effort, open questions still intrigue us, such as the coexistence of molten oxyanionic salts and the glassforming borate melt in the early stages of conversion, or the relationship between the glass-forming melt fraction and the properties and characteristics of primary foaming.…”

Section: Introductionmentioning

confidence: 99%

“…An improved understanding of these physico‐chemical processes occurring in the cold cap is critical for optimizing the vitrification process, including achieving a consistent high melting rate, 13,14 maximizing the retention of volatile elements (e.g., technetium or iodine), 15,16 and limiting the formation of crystalline species (e.g., nepheline) that can compromise the quality of the final product 17,18 . This is especially true for the vitrification of low‐activity waste, which is a technologically much less mature process, because LAW was historically treated using other technologies, such as cementation, bituminization, or compaction and containerization 19–21 …”

Section: Introductionmentioning

confidence: 99%

Transient melt formation and its effect on conversion phenomena during nuclear waste vitrification – HT‐ESEM analysis

Pokorný,

Vernerová,

Kloužek

et al. 2023

J Am Ceram Soc.

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Although the vitrification of nuclear waste has a decades‐long history, numerous opportunities still exist to improve its efficiency and to increase the waste loading in glass. This is especially true for the vitrification of low‐activity waste (LAW), which has been historically treated by other immobilization technologies and is less mature than high‐level waste (HLW) vitrification. In this work, we address one of the least understood phenomena during the conversion of nuclear waste feeds to glass—the formation of molten salt and transient glass‐forming melt. Using high‐temperature environmental scanning electron microscopy (HT‐ESEM) in combination with X‐ray diffraction, thermogravimetry, and evolved gas analysis, we have analyzed the complex chemical reactions and phase transitions as they occur during melting of representative HLW and LAW melter feeds. We evaluated the compositions of amorphous phases and the fractions of salt components, and estimated the fractions of molten salt phases present in the feeds as a function of temperature. We show that the maximum fraction of molten salts is ∼4 % and ∼28 % during HLW and LAW feed melting, respectively, and discuss the possibility of molten salt migration in LAW feeds. We also argue that the presence of significant fractions of molten salt phase can hinder the retention of rhenium (and, hence, radioactive technetium), and discuss how the properties of molten salt phase and transient glass‐forming melt are related to primary foam formation and behavior. Finally, we summarize key unanswered questions requiring further research to increase the understanding of the conversion process and enhance the nuclear waste vitrification efficiency.

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“…Similar sludges are also abundant at the Hanford sites in the USA, and both glass and ceramic waste forms have been developed to immobilize sludges alone [7][8][9]. In addition, many studies have focused on the thermal treatment of other types of radioactive sludge, such as Magnox sludge [10,11] and Fukushima sludge [12], to form glass or ceramic wasteforms.…”

Section: Introductionmentioning

confidence: 99%

Influence of Radioactive Sludge Content on Vitrification of High-Level Liquid Waste

et al. 2023

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The radioactive sludges formed at the bottom of high-level liquid waste (HLW) storage tanks pose challenges when the HLWs are vitrified. This study aims to determine the influence of the sludge content (enriched in Na2O, Al2O3, NiO, Fe2O3, and BaSO4) on the structure and properties of waste glasses in order to find the optimal ratio of sludges to HLW during vitrification. In the experiments, the simulated sludge and simulated HLW were mixed at different ratios from 0:8 to 4:4, with an overall waste content of 16 wt %, in a borosilicate glass wasteform. It is found that the glass density, molar volume, sulfur retention, and glass transition temperature changed little when increasing the sludge content of the glasses, while the viscosity, chemical durability, and crystallization features of the glasses varied notably. The crystals formed in the glasses during the thermal treatment were exclusively Fe-substituted diopside (Ca, Mg, Fe)2Si2O6. An increase in the Al2O3 and NiO content of the glasses may have been responsible for the increased crystallinity at high temperatures. The leaching rate of Si, B, Na, and Cs from the glasses declined with the increasing addition of sludge to the glasses. Although all the glasses fulfilled the requirements for vitrification processing and glass-product performance, it is recommended that the sludge content of the whole waste should not exceed 25 wt %. This study guides further research on the immobilization of high-level sludges.

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Vitrification of an intermediate level Magnox sludge waste

Cited by 17 publications

References 22 publications

Nuclear Waste Management

Nuclear Waste Management

Transient melt formation and its effect on conversion phenomena during nuclear waste vitrification – HT‐ESEM analysis

Influence of Radioactive Sludge Content on Vitrification of High-Level Liquid Waste

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