Radiation shielding material, process for manufacture and apparatus
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Solution Overview
Problem
Current lead-based radiation shielding materials pose environmental and health risks due to toxicity and contamination, and existing alternatives like pure bismuth are brittle and unsuitable for machined parts.
Innovation Solution
Development of bismuth-tin-antimony alloys with specific atomic fractions that provide machinable, non-toxic, and structurally stable radiation shielding, offering attenuation equivalent to lead up to 500 keV, suitable for various applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-based shielding materials are used, then radiation attenuation is effective, but environmental and health risks increase due to toxicity
Solution Approach 1:
The patent changes the chemical composition parameters by replacing lead with bismuth as the base metal and adjusting the alloy composition to contain 5-20 atomic percent tin and 5-20 atomic percent antimony. This parameter change maintains the high density and radiation attenuation properties while eliminating the severe toxicity associated with lead, thus resolving the contradiction between effectiveness and harmful factors
Solution Approach 2:
The patent creates a composite alloy material combining bismuth, tin, and antimony in specific proportions. This composite approach leverages the high density and low toxicity of bismuth, the ductility and machinability improvements from tin, and the structural stability from antimony, achieving both effective radiation shielding and reduced environmental harm
2Object-affected harmful factors
If pure bismuth is used as shielding material, then toxicity is reduced, but mechanical stability deteriorates due to brittleness
Solution Approach 1:
The patent develops a composite alloy system where bismuth is combined with tin and antimony. The tin addition (5-20 at%) improves ductility and machinability, while antimony (5-20 at%) enhances structural stability and strength. This composite material approach maintains the low toxicity of pure bismuth while correcting its brittleness, enabling practical machining and structural applications
Solution Approach 2:
The patent optimizes the local composition within the alloy by distributing tin and antimony atoms throughout the bismuth matrix in specific concentrations. This local quality adjustment ensures that the beneficial properties of each element are maximized at the atomic level, providing both mechanical stability and radiation shielding performance throughout the material
3Reliability
If lead alloys are used for radiation shielding, then radiation attenuation is effective, but environmental contamination increases
Solution Approach 1:
The patent fundamentally changes the material composition parameter by substituting lead with bismuth as the primary metal. Bismuth has similar density (9.78 g/cm³ vs. lead's 11.34 g/cm³) and effective radiation attenuation properties, but it is classified as a less toxic heavy metal. This parameter change eliminates the severe environmental contamination issues associated with lead disposal and occupational exposure while maintaining shielding effectiveness
Solution Approach 2:
The patent converts the historical harm caused by lead's toxicity into a benefit by using bismuth, which shares lead's desirable physical properties for radiation shielding but lacks its severe toxicity. The low melting point of bismuth (271°C vs. lead's 327°C) also provides processing benefits, allowing for easier casting and forming while eliminating environmental harm
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 alloys offer effective radiation shielding with reduced environmental and health risks, maintaining mechanical stability and attenuation properties, making them a viable lead replacement in radiation sources below 500 keV.
Implementation Method 1
shielding calculations and experimentation revealed that materials with high atomic number (Z), and high density, attenuate photon based ionizing radiations with efficiency
Data Source
AI summary
An alloy consisting of bismuth, tin and antimony is described. In embodiments, the alloy may comprise substantially Sn = 3.4 - 9.8at% (2.0% - 6.0% by weight), Sb = 4.3 - 4.8at% (2.6% - 2.9% by weight), and Bi = 85.6 - 92.4at% (91.2% - 95.5% by weight). Indium may replace the tin component. The alloy may be used as a radiation shield. A process for preparing and forming the alloy is described.