Vitrification Additive Redistribution for Secondary Phase Suppression
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Solution Overview
Problem
The formation of undesirable secondary phases during the vitrification of radioactive waste materials, such as molybdate and sulfate phases, leads to processing and product quality issues, including corrosion and reduced waste loading, which are not effectively addressed by existing methods.
Innovation Solution
The method involves redistributing Al2O3 and B2O3 from the glass frit additive to be mixed separately with the radioactive high-level waste, along with SiO2, to suppress the formation of secondary phases by altering the feed chemistry, thereby increasing waste loading and reducing secondary phase accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional glass frit additives are used during waste vitrification, then the melting process can proceed, but undesirable secondary phases such as molybdate and sulfate phases form, leading to product quality issues and reduced waste loading
Solution Approach 1:
The patent changes the chemical parameters of the additive by redistributing Al2O3 and B2O3 from the glass frit to separate raw chemical form. This parameter change in the additive's chemical composition and physical state suppresses the formation of secondary phases by altering the reaction kinetics and thermodynamics in the cold-cap region, thereby improving waste loading capability
Solution Approach 2:
The patent segments the glass frit additive into separate raw chemical components (Al2O3 and B2O3) that are mixed with the waste material before melting. This segmentation allows for better control of chemical reactions during the melting process and prevents the formation of undesirable secondary phases, thus resolving the contradiction between productivity and harmful factors
2Reliability
If high concentrations of molybdenum and sulfur are present in the waste material, then the waste can be processed, but persistent secondary phases form that are easily leachable and cause corrosion, reducing product durability
Solution Approach 1:
The patent changes the chemical parameters of the additive system by providing Al2O3 and B2O3 as separate raw chemicals rather than in glass frit form. This parameter change suppresses the formation of leachable secondary phases by modifying the chemical environment in the cold-cap, thereby improving product durability and reducing harmful leachable phases
Solution Approach 2:
The patent converts the potentially harmful interaction between molybdenum/sulfur and glass frit into a beneficial outcome by using separate Al2O3 and B2O3 chemicals. This approach suppresses secondary phase formation and actually improves waste loading capability, turning a harmful situation into a benefit
3Productivity
If molybdate phases accumulate on the melt surface, then the melting process continues, but excessive corrosion of melter components occurs
Solution Approach 1:
The patent changes the physical and chemical parameters of the additive by using separate Al2O3 and B2O3 chemicals instead of glass frit. This parameter change suppresses molybdate phase formation at the melt surface, thereby preventing corrosion of melter components while maintaining continuous melting process operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses the formation of secondary phases, increasing waste incorporation into the glass product and improving product quality, leading to cost savings and enhanced processing efficiency.
Implementation Method 1
redistributing Al2O3 and B2O3 from the glass frit additive to be mixed separately with the radioactive high-level waste, along with SiO2, to suppress the formation of secondary phases by altering the feed chemistry
Implementation Method 2
Vitrification of radioactive high level waste (HLW) to produce a borosilicate glass product is the internationally accepted waste treatment method
Implementation Method 3
melted at a high temperature (typically 1150°C for JHCMs, typically somewhat lower for IMs, and typically somewhat higher for CCMs) in order to produce glass products
Data Source
Figure 1
AI summary
A method for vitrification of high level waste to reduce the formation of persistent secondary phases comprising the steps of providing a high level waste for vitrification; providing a glass frit additive for mixing with said high level waste; redistributing selected constituents of said glass frit for mixing separately as raw chemicals with said high level waste; and, feeding said high level waste, said glass frit additive, and the redistributed glass frit constituents to a melter for vitrification of said high level waste so that formation of secondary phases is suppressed.