Radionuclide Hydroxide Solidification Using Low Melting Point Glass
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Solution Overview
Problem
Current solidification methods for radionuclide-containing waste, such as those generated from nuclear power plant decontamination processes, face issues with thermal stability and bulk density due to the production of ettringite when using cement and the low density of geopolymer-based waste forms, which are unsuitable for high heat-resistant nuclides like Co-60.
Innovation Solution
A method involving the use of a low melting point glass powder composed of Bi2O3, B2O3, ZnO, and SiO2, mixed with radionuclide hydroxides and BaSO4, and then heated to create a stable, high-density waste form with improved thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If cement is used for solidification, then the waste form can be produced, but ettringite is produced causing expansion and cracking, resulting in poor thermal stability
Solution Approach 1:
The patent changes the chemical composition parameters by replacing cement with a specific glass composition containing Bi2O3 (40-70 wt%), B2O3 (10-30 wt%), ZnO (5-20 wt%), and SiO2 (5-20 wt%). This compositional change prevents ettringite formation while achieving thermal stability up to 600°C and appropriate bulk density (2.5-3.5 g/cm³), directly resolving the contradiction between waste form production and thermal stability.
2Stability of the object's composition
If geopolymer based on metakaolin is used, then high compressive strength and chemical stability are achieved, but bulk density is low (1.5 to 2.0 kg/L) and weight loss of 20% or more occurs at temperatures within 200° C., resulting in low thermal stability
Solution Approach 1:
The patent creates a composite glass material combining multiple oxides (Bi2O3, B2O3, ZnO, SiO2) in specific proportions. This composite structure achieves high bulk density (2.5-3.5 g/cm³) while maintaining thermal stability up to 600°C, overcoming the low density and poor thermal stability of geopolymer-based waste forms.
3Productivity
If geopolymer based on metakaolin is used, then waste form can be produced, but a large amount of time (minimum 7 days) is required for preparing the waste form
Solution Approach 1:
The patent changes the preparation parameters by using a glass-based system that can be processed at lower temperatures (400-600°C) compared to geopolymer curing. This reduces the preparation time from a minimum of 7 days to a few hours while maintaining chemical stability through the formation of a stable glass matrix that immobilizes radionuclides.
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 method produces a waste form with significantly higher bulk density and thermal stability compared to geopolymer-based methods, reducing waste volume and improving disposal efficiency, while being cost-effective and applicable to various nuclear facility wastes.
Implementation Method 1
heating the glass mixture
Implementation Method 2
providing a low melting point glass including Bi2O3, B2O3, ZnO and SiO2; providing a glass mixture by mixing a mixture to be treated containing a hydroxide of a radionuclide and BaSO4, and the low melting point glass; and heating the glass mixture
Data Source
AI summary
The present disclosure provides a solidifying method of a radionuclide. The solidifying method of the radionuclide includes operations of: providing a low melting point glass including Bi2O3, B2O3, ZnO and SiO2; providing a glass mixture mixing a mixture to be treated containing a hydroxide of radionuclide and BaSO4 and the low melting point glass; and heating the glass mixture.