Densified Waste Form Using Compacted Metallic Powder Matrix
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Solution Overview
Problem
Current methods for sequestering and storing radioactive iodine from nuclear reactor fuel cycles and nuclear legacy wastes are inadequate due to the volatility and solubility issues of iodine, leading to potential contamination and release during storage or handling, particularly with conventional glass waste forms and silver-loaded zeolites, which require high temperatures and may not retain iodine effectively.
Innovation Solution
A densified waste form is created using a compacted metallic powder matrix that encapsulates temperature-sensitive waste materials like AgI or MOFs, allowing for low-temperature processing and room temperature fabrication, providing mechanical strength and low iodine outgassing, achieved by mixing metallic powders with temperature-sensitive waste materials and compacting them under high pressure to form a physically densified matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional glass waste forms are used to sequester radioactive iodine, then the waste form provides a stable matrix for immobilization, but the high temperature processing required to melt the glass causes iodine sublimation and release
Solution Approach 1:
The patent changes the processing temperature parameter from conventional glass melting temperatures (>1000°C) to low-temperature sintering (550°C). This parameter change allows the waste form to be processed at temperatures below the iodine sublimation point while still achieving adequate densification and immobilization of radioactive iodine in the glass matrix.
2Reliability
If silver-loaded zeolite is used to capture radio-iodine, then the iodine is sequestered in sub-micron crystals, but the zeolite is crushable and forms powders and dust under mechanical damage
Solution Approach 1:
The patent creates a composite waste form where silver-loaded zeolite particles are embedded within a glass matrix. The glass provides mechanical strength and structural integrity, preventing the crushable zeolite from forming dust, while the zeolite maintains its iodine sequestration capability. The composite structure combines the advantages of both materials while mitigating their individual weaknesses.
3Reliability
If silver-loaded zeolite is sintered at high temperature (500-700°C) to create densified ceramic, then the iodine is retained as AgI, but the sintering temperature causes sublimation of AgI and release of gaseous iodine
Solution Approach 1:
The patent changes the sintering temperature parameter to 550°C, which is below the sublimation temperature of AgI (600°C). This parameter change prevents iodine loss through sublimation while still achieving adequate densification of the glass matrix and retention of iodine in the AgI phase within the sintered waste form.
4Object-affected harmful factors
If radio-iodine is discharged to ocean for isotope dilution, then the concentration of iodine in the environment is reduced, but this method is no longer acceptable and alternative disposal methods are needed
Solution Approach 1:
The patent changes the disposal approach from environmental release (ocean discharge) to secure immobilization (low-temperature sintered glass waste form). This parameter change in disposal methodology eliminates environmental contamination risks while providing a stable, long-term storage solution that meets modern regulatory requirements for radioactive waste management.
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
The solution results in a stable, durable, and cost-effective waste form with low iodine leaching and outgassing, suitable for long-term storage, which effectively immobilizes radioactive iodine and other volatile fission gases, addressing the limitations of existing technologies by avoiding high-temperature processing and maintaining the integrity of the encapsulated materials.
Implementation Method 1
The waste form precursor is compacted with sufficient pressure to densify the waste precursor and encapsulate the temperature sensitive waste material in a physically densified matrix
Data Source
AI summary
Materials and methods of making densified waste forms for temperature sensitive waste material, such as nuclear waste, formed with low temperature processing using metallic powder that forms the matrix that encapsulates the temperature sensitive waste material. The densified waste form includes a temperature sensitive waste material in a physically densified matrix, the matrix is a compacted metallic powder. The method for forming the densified waste form includes mixing a metallic powder and a temperature sensitive waste material to form a waste form precursor. The waste form precursor is compacted with sufficient pressure to densify the waste precursor and encapsulate the temperature sensitive waste material in a physically densified matrix.