Bismuth-Based Porous Adsorbent for Radioactive Iodine Trapping
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Solution Overview
Problem
Current adsorbents for trapping radioactive iodine gas, such as silver-containing zeolites, are expensive, toxic, and lack thermal stability, making them inefficient for long-term storage and disposal of nuclear fuel waste.
Innovation Solution
A bismuth-based adsorbent is developed through a method involving the preparation of a mixed solution with bismuth nitrate and polyvinylalcohol, followed by drying, heat-treating in an atmospheric environment, and reducing in a hydrogen atmosphere to create a porous, economically viable adsorbent with enhanced iodine trapping performance and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver-containing zeolite is used to trap radioactive iodine gas, then iodine trapping performance is improved, but manufacturing cost increases and toxicity issues arise
Solution Approach 1:
The patent replaces expensive silver-containing zeolite with a cheaper bismuth-based adsorbent material. The bismuth adsorbent achieves comparable or superior iodine trapping performance while significantly reducing manufacturing costs and eliminating the toxicity concerns associated with silver disposal.
2Reliability
If silver-containing zeolite is used to trap radioactive iodine gas, then iodine trapping performance is improved, but thermal stability of trapped iodine deteriorates
Solution Approach 1:
The patent changes the chemical composition parameter from silver-based to bismuth-based adsorbent material. This parameter change fundamentally alters the thermal stability characteristics, allowing the trapped iodine to maintain stability at higher temperatures (up to 1000°C) compared to silver-containing zeolite, which suffers from sintering at these temperatures.
3Reliability
If silver-containing zeolite is used to trap radioactive iodine gas, then iodine trapping performance is improved, but sintering occurs during high-temperature thermal treatment
Solution Approach 1:
The patent employs a bismuth-based adsorbent that maintains structural integrity during high-temperature thermal treatment up to 1000°C, preventing the sintering issues that plague silver-containing zeolite. The bismuth material's higher melting point and thermal stability make it suitable for long-term disposal requirements.
4Ease of manufacture
If bismuth-based adsorbent is used instead of silver-containing zeolite, then manufacturing cost decreases and thermal stability improves, but iodine trapping capacity must be maintained
Solution Approach 1:
The patent optimizes the bismuth-based adsorbent's physical and chemical parameters including pore size, surface area, and bismuth content to achieve iodine trapping capacity comparable to or exceeding silver-containing zeolite. The controlled synthesis process ensures consistent performance while maintaining cost advantages and thermal stability benefits.
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 bismuth-based adsorbent demonstrates superior iodine trapping capacity, twice that of commercial silver-containing zeolites, with improved thermal stability, making it suitable for long-term storage and disposal of radioactive iodine gas without the toxicity and cost issues of silver-based solutions.
Implementation Method 1
preparing a mixed solution by mixing a solution including bismuth nitrate at 10 to 20 wt % and a solution including polyvinylalcohol at 10 to 20 wt %
Implementation Method 2
preparing a mixture by drying the mixed solution to remove moisture
Implementation Method 3
preparing an oxide by heat-treating the mixture in an atmospheric ambience to remove polyvinylalcohol
Implementation Method 4
reducing the oxide to a bismuth element state by heat-treating the oxide in a hydrogen ambience
Implementation Method 5
A porous adsorbent for trapping radioactive iodine gas... bismuth-based adsorbent demonstrates superior iodine trapping capacity
Data Source
AI summary
Provided are an adsorbent for trapping a radioactive iodine gas generated in a process of oxidizing a nuclear fuel at a high temperature after use and a method of preparing the same, and more particularly, a radioactive iodine gas adsorbent which is formed of bismuth as a main component, thereby exhibiting an excellent radioactive iodine gas trapping capability and an excellent thermal stability after trapping, and a method of preparing the same.An adsorbent for trapping a radioactive iodine gas prepared by a method of preparing an adsorbent for trapping a radioactive iodine gas according to the present disclosure may effectively trap a radioactive iodine off-gas generated in a nuclear fuel pre-treated oxidizing process after use.Particularly, the adsorbent may trap iodine in a larger amount, which is twice or more, than a silver-containing zeolite widely used to trap a radioactive iodine gas, and the trapped iodine forms a stable compound, which is more advantageous for long-term storage.In addition, since an iodine gas is trapped using inexpensive bismuth, instead of expensive silver, in consideration of trapping a large amount of a radioactive iodine gas, the adsorbent has very excellent economic feasibility.