Cesium Trap Carbonation for Sodium Waste Treatment
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Solution Overview
Problem
The treatment of sodium-cooled Fast Neutron Reactor waste containing cesium isotopes is challenging due to the retention of sodium in cesium traps, leading to dual safety and security risks, and existing methods like hydrolysis generate liquid waste and require difficult cutting operations in radioactive environments.
Innovation Solution
A method involving the formation of slits in the cladding of cesium traps to facilitate a carbonation reaction with a steam and carbon dioxide mixture, which expands to open the structure and convert sodium into stable, inert sodium carbonate, allowing for deep penetration and treatment without additional cutting operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If hydrolysis reaction is used to treat sodium, then sodium is converted to sodium hydroxide, but liquid waste is generated and difficult control is achieved
Solution Approach 1:
The invention changes the chemical reaction parameter from hydrolysis (Na + H2O → NaOH) to carbonation (NaOH + CO2 → Na2CO3). This parameter change transforms the product from liquid sodium hydroxide to solid sodium carbonate, eliminating liquid waste generation while maintaining ease of sodium treatment.
Solution Approach 2:
The invention utilizes phase transition by converting sodium from solid metal form to solid carbonate form through a two-step process: first hydrolysis to sodium hydroxide, then carbonation to sodium carbonate. This phase transition eliminates the liquid waste intermediate and achieves complete solid-to-solid transformation.
2Ease of operation
If cutting operations are performed in glove box to access sodium, then sodium becomes accessible for treatment, but radioactive contamination of tools occurs and manipulation difficulty increases
Solution Approach 1:
The invention applies preliminary action by pre-opening slits in the cladding before introducing the reactive gas mixture. This preliminary structural modification allows the gas to penetrate and react with sodium deep within the porous structure without requiring cutting operations inside the glove box, thus preventing radioactive contamination of tools while maintaining accessibility.
Solution Approach 2:
The invention replaces mechanical cutting operations with a chemical/gas-based approach. Instead of mechanically cutting into the cladding and porous structure inside the glove box, the system uses a reactive gas mixture that chemically reacts with sodium through pre-opened slits, eliminating the need for mechanical manipulation in the radioactive environment.
3Ease of operation
If cladding is cut open to access sodium in porous structure, then sodium becomes accessible, but handling operations become more difficult in radioactive environment
Solution Approach 1:
The invention applies preliminary action by pre-opening slits in the cladding before introducing the reactive gas mixture. This preliminary structural modification allows the gas to penetrate and react with sodium deep within the porous structure without requiring cutting operations inside the glove box, thus preventing radioactive contamination of tools while maintaining accessibility.
4Ease of manufacture
If conventional waste processing systems are used, then sodium must be removed from trap, but chemical risk remains due to residual sodium requiring inert atmosphere
Solution Approach 1:
The invention changes the chemical reaction parameter from hydrolysis (Na + H2O → NaOH) to carbonation (NaOH + CO2 → Na2CO3). This parameter change transforms the product from liquid sodium hydroxide to solid sodium carbonate, eliminating liquid waste generation while maintaining ease of sodium treatment.
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 method effectively treats sodium in cesium traps by producing solid waste, minimizing radioactive exposure, and enabling secure, controllable, and cost-effective processing of large quantities with reduced risk of chemical and radiological hazards.
Implementation Method 1
the sodium is converted to sodium carbonate by a carbonation reaction, by bringing the structure into contact, via the slits, with a reactive gas mixture comprising steam, carbon dioxide
Implementation Method 2
CO2+H2OH2CO3 NaOH+H2CO3NaHCO3+H2O NaOH+NaHCO3Na2CO3+H2O
Implementation Method 3
the expansion of the carbonate causes the cladding and the structure to open starting from the slits
Data Source
AI summary
Method of treating sodium contained in the interconnected open pores of a structure placed in a cladding, the pores furthermore containing a radioactive substance. The method comprises the following successive steps: a) at least two slits are made over the entire length of the cladding; b) the sodium is converted to sodium carbonate by a carbonation reaction by bringing the structure into contact, via the slits, with a reactive gas mixture comprising steam, carbon dioxide and a gas inert with respect to sodium, in such a way that the expansion of the carbonate causes the cladding and the structure to open starting from the slits and results in the carbonation reaction propagating into the structure.