What Blocks Radiation? Materials Used in Radiation Shielding

Radiation contamination is always a concern anywhere radioactive materials or tools are used, which is why radiation shielding products are essential to any ALARA program or a relevant company safety program. This includes nuclear power facilities and industrial complexes, to medical facilities where x-rays are used, and any other “radioactive workspaces.”

Containing the radiation and preventing it from harming employees, contaminating tools or contaminating the surrounding environment should be a Number One priority. This happens in a variety of ways – tents and ventilation systems, sleeving and bags, suiting up in protective clothing, etc. – but how does all that stuff work?

What is it about radiation shielding products that actually works to stop one of the deadliest contaminants in our environment?

Radiation Shielding Products Depend on the Type of Radiation in Question

There are two different “genres” of radiation: indirectly ionizing radiation and directly ionizing radiation.

• Indirectly ionizing radiation. This type includes neutrons, gamma rays or x-rays, which are uncharged and require an intermediary in order to remove an electron and create free radicals.
• Directly ionizing radiation. This type of radiation involves charged particles – such as electrons or alpha particles, that act directly on molecules or atoms without any intermediary step or element required.

As a result of these differences, the materials comprising the shielding products are key – ensuring specific particles are blocked by the elemental properties of the shielding material.

Shielding Products Rob Radioactive Particles of Their Energy

Ultimately, radiation shielding products are designed to facilitate attenuation. Attenuation means the gradual loss of intensity as a particular particle or substance flows or moves through a barrier. So, for example, sunglasses provide attenuation, diminishing the power of sunlight as it makes its way from the sun, through the dark tinted glasses, and into your eyes.

In the case of radiation shielding, we aim to attenuate the particles that would otherwise have the ability to interact with cellular material and destroy healthy DNA.

• Charged particles: These are usually de-energized by barriers that contain electrons. The charged particles lose energy to the electrons in the barrier and are no longer threatening.
• Neutrons: When we use a combination of elastic and inelastic scattering, we reduce the potential harm of neutrons.
• X-Rays and Gamma Rays: These are attenuated in three ways – photoemission (the process of exposing certain metals to light in order to release electrons), scattering (using a material that causes the particles to scatter, significantly diminishing their trajectory and concentration) and pair production.

Depending on the scenario, your place of business might opt for one shielding material over another, depending on considerations such as:

• Effectiveness
• Resistance to damage in a particular environment/setting
• Strength
• Thermal properties
• Financial efficiency

Gamma and X-Ray Shielding

When it comes to attenuating gamma and x-rays, density matters. This is one of the reasons why lead aprons and blankets are the most common shielding products wherever gamma-rays or x-rays are used. If you may recall from earth science or chemistry, lead (Pb) had a very high number or protons in each atom – 82, to be exact, along with a corresponding number of electrons. This makes it a very dense metal shield. The thickness of the shielding is adjustable according to the degree of protection required.

Even so, a small number of particles can still make it through so this needs to be taken into consideration is routine exposure is potential.

Alpha and Beta Shielding

In the case of alpha and beta shielding, we still place an emphasis on density but thickness is not as much of a concern as it is with x-rays and gamma rays. Alpha particles can be blocked by something as simple as a centimeter of plastic or an inch of paper. Since lead doesn’t always stop beta particles, we prefer to use plastic to block these particles as well, which is efficient in terms of economics as well as maneuverability.

Neutron Shielding

Neutrons have no charge, and so they can pass through dense materials – like lead – as quick as they please. Thus, we need elements with a low atomic number to stop neutron radiation. Hydrogen, the very lightest of the elements – becomes an ideal choice. When neutron radiation passes through the very un-dense hydrogen-based materials (water being a prime example) the low-density material forms a barrier, preventing neutron particles from passing through.

That being said, the act of blocking the neutrons can cause low-density materials to emit gamma-rays when blocking neutrons, so we typically combine both low- and high-density materials. The low-density materials create the elastic scattering of the neutrons, and then the high-density material blocks the resulting gamma rays via in-elastic scattering.

Want to make sure your company is using the right radiation shielding project for the job? Contact the team here at Lancs Industries. We’ll work with you to find the best product, at the right price. Don’t see what you need on our website? We are always happy to customize specific products to your needs.