When choosing an attenuating material for radiation shielding, the most important characteristic is high density. Tungsten (atomic symbol W) has many advantages over the lead. It’s non-toxic and easily recycled, thus it poses no risk to people or the environment. It can also be reduced to a layer a fraction of the thickness of lead to provide the same amount of shielding.
Tungsten’s high tensile strength, machinability, radiographic density, and heat resistance make it adaptable to many different designs of shielding. In fact, its name is derived from the Swedish for “heavy stone”. Tungsten is very tough stuff!
What Are the Properties of Tungsten?
#1. What Is the Density of Tungsten?
- Density can be defined as mass per unit volume—in other words, the heaviness of a specified volume of a substance.
- Tungsten is about 1.7x denser than lead. Its density is approximately 11.13 oz/inch3 (or 19.25 g/cm3). By comparison, lead has a density of around 6.56 oz/inch³ or (11.34 g/cm3).
- The atoms of tungsten are packed together more tightly than lead, and therefore more resistant to penetration by potentially harmful ionizing radiation.
#2. What Is the Melting Point of Tungsten?
- In its pure form, tungsten has the highest melting point of all the metals—6,170oF (3,410oC).
- Because tungsten has such a high melting point, it’s nearly impossible and very impractical to smelt or cast.
- Tungsten usually comes in a powdered form, which is compressed under very high pressure to produce a solid. This process is called sintering.
#3. What Is the Tensile Strength of Tungsten?
- Tungsten has incredible tensile strength, which is the amount of stress it can handle before it stretches and breaks.
- Its tensile strength is about 142,137 psi (980 MPa).
What Is Tungsten Shielding?
When it comes to shielding, tungsten has incredible stopping power—high energy electromagnetic frequency (EMF) radiation such as x-rays and gamma rays find it very hard to penetrate tungsten.
Each atom has 74 protons in a very compact and positively charged nucleus, surrounded by a tightly held electron cloud of 74 electrons. When bombarded with ionizing EMF radiation, the harmful rays rapidly lose their kinetic energy as it is transferred to the electrons. This process is called attenuation.
Because of its excellent attenuation properties, particularly for protecting against x-rays and gamma rays, tungsten shielding is widely used in nuclear medicine. It’s found in radioactive source containers, gamma radiography shields, shielding blocks, x-ray collimators, cancer therapy machines, syringe shields for radioisotopes, nuclear shielding walls, etc.
With recent advances in metallurgical and materials sciences, tungsten can now be used in the fabrication of thin, flexible, lightweight liners for radiation protection aprons and other personal protective equipment. These offer comparable protection to the standard lead apron, with many advantages.
Advantages of Tungsten Radiation Shielding
- Tungsten is much denser than lead and its atoms are packed more tightly together. A layer one-third as thick as a layer of lead will provide an equivalent amount of protection against harmful scatter radiation.
- Tungsten can be alloyed with other attenuating substances to lighten the weight. This is achieved by sintering with other metals or compounds, such as titanium.
- Tungsten alloys can be mixed to form amalgamates which can have specifically selected attributes for radiation shielding.
- Tungsten amalgamates can be embedded in polymer matrices such as vinyl to produce flexible material that doesn’t crack easily, oxidize, corrode or shed toxic dust.
Tungsten vs. Lead Shielding – How Do They Compare?
| Comparison of Tungsten and Lead for Radiation Shielding | ||
|---|---|---|
| Property | Tungsten Shielding | Lead Shielding |
| Density | Tungsten is approximately 1.7x denser than lead and about 60% heavier. Its atoms are smaller but packed more tightly. | Lead is very dense and heavy. Its atoms are larger than tungsten, but not packed quite as tightly together. |
| Corrosion Resistance | Tungsten is extremely corrosion resistant and doesn’t react easily with oxygen, except at very high temperatures. | Lead is highly corrosion resistant in water. However, it is susceptible to gaseous oxides, alkalis in soap and cement, and acids in wood. |
| Radiation Absorption | Its attenuating properties are considerably greater than lead, especially for gamma rays. Its heat resistance with a melting point of 6,170oF (3,410oC) is very beneficial in highly radioactive environments. | Lead is very effective at absorbing x-rays and gamma rays. It has efficient shielding properties at a comparatively lower cost than tungsten. However, it has a very low melting point of 621.5oF (327.5oC). |
| Ease of fabrication and machining | Tungsten is very hard to cast, but in its powdered form, it can be embedded in matrices such as vinyl. It can be alloyed with other attenuating substances to decrease weight. | Lead is flexible, malleable, and ductile, and can be formed into plates, sheets, foil, wires, wool, etc. It’s a highly versatile metal that can be used in a variety of fabrications and forms. |
| Toxicity | Tungsten is non-toxic and doesn’t form harmful dust. It’s eco-friendly and doesn’t require any special disposal protocols | Lead is very toxic and can cause irreversible neurological and physiological effects. It requires special disposal protocols. |
Try Our Tungsten-Based Lightweight Radiation Aprons
Barrier Technologies® brings superior and innovative tungsten shielding right to you—in fact, right onto your body! Our cutting-edge research and development specialists offer you the benefits of our lead-free, tungsten-based alloy blends, and lightweight radiation protection aprons. These have several advantages over standard lead aprons:
- Get maximum protection: Our Pb-free™ aprons are made from a proprietary amalgamation of tungsten alloys of titanium, bismuth, and magnesium encapsulated in a vinyl matrix, which is equally effective at blocking scatter radiation.
- Carry minimal weight: Encapsulated in a vinyl matrix, our tungsten alloy options are significantly lighter than lead. This will relieve you of the fatigue and musculoskeletal problems associated with heavy lead aprons.
- Protect your health and the environment: Tungsten is non-toxic and tougher than lead. Your apron will have greater durability and it requires no special disposal protocols when it reaches the end of its serviceable lifespan.
Contact Barrier Technologies Today
Barrier Technologies is at the forefront of innovation in radiation shielding products and materials. Our lightweight aprons bring you the advantages of tungsten’s radiographic density. Let us protect you against the hazards of scatter radiation without weighing you down. Free yourself from that heavy lead apron today! Contact us for more information or to place your order.
