Isotopes, such as Californium-252 and others, emit neutrons in the process of radioactive decay. While this makes them highly effective for material analysis and detection in oil and gas drilling, concrete manufacturing, defense, and nuclear fission applications, it also makes them a threat to the health and safety of workers and researchers.
Neutron-emitting sources must be properly shielded during transportation and daily use in research, industry, and nuclear energy settings. Here, we’ll look at ways to accomplish this effectively.
Common Neutron Shielding Materials
Many materials may be used to shield against ionizing radiation. Some of the most common neutron shielding materials include:
- Paraffin: Paraffin is a waxy hydrocarbon material derived from petroleum. It is often enriched with heavy metal atoms to create an effective composite shielding material. Paraffin-boric acid shields, for instance, both attenuates high-energy neutrons and absorbs those of lower energy. A key drawback is its relatively low melting point, which can lead to compromised shielding.
- Concrete: Concrete is another of the more conventional shielding materials. It is among the most affordable options, and its moldability means it can be used for almost any shape. However, concrete’s shielding performance depends on environmental conditions, and it can be prone to cracks.
- WEP Resin: Water-extended polyester (WEP) resin is an innovative shielding material that is highly effective for neutron shielding. WEP is easy to apply and offers high mechanical strength and durability. It performs well at temperatures up to 500°F (260°C), and it resists degradation from weathering or chemical exposures.
It is important to note that heavy metals, such as lead, are not used in neutron shielding.
Hydrogen: Critical for Shielding
What makes a neutron shield effective is its ability to slow and block energized neutrons as they travel. Shielding material that contains hydrogen is superior because hydrogen molecules are large, which means neutrons collide with them readily and decrease in speed.
What is WEP?
WEP resin is a newer shielding choice valued for water’s high hydrogen availability. Due to its high content of large, neutron blocking hydrogen molecules, WEP is a highly effective shielding material. It also contains boron, an element that absorbs neutrons and adds additional shielding capability.
WEP resin is strong, versatile, durable, and offers better neutron shielding performance than some high-density options.
WEP resin consists of solid polyester beads emulsified with water and then cured. It also contains fillers that improve stability and appearance. Its castability, electron density, light weight, and low cost make it an excellent choice for neutron shielding in different applications.
WEP Resin in Neutron Shielding
WEP resin can be used in places where it is necessary to enclose radioactive sources and capture the free neutrons that are emitted, such as:
- Thick fillings in steel drums for transporting encapsulated neutron sources like Californium-252
- Filling shielding walls in Small Modular Reactors and other settings that use neutron sources (e.g., medical or research labs)
- Filling stainless steel boxes that house neutron sources in oil and gas, coal, or concrete manufacturing settings
Frontier’s custom WEP shielding protects personnel in industries such as nuclear energy, research, and medicine.
How is WEP Resin Made?
WEP resin is made from a proprietary mixture of water, polyethylene beads, resin, and boron. It can be cast and cured to form a variety of shapes.
Benefits of Using WEP over Other Neutron Shielding Materials
Key benefits of WEP over other shielding materials include:
- High Water Content: As a result of the emulsification process, WEP resin’s final hydrogen content is almost as high as that of pure water. Water itself is an extremely effective neutron shield, though it can be difficult to use in some applications. Unlike water, WEP resin cures into a hard shield, so it can easily be used in almost any shielding application.
- Cost-Effective: WEP resin’s high water content makes it a very affordable substance by weight compared to alternative materials like concrete or paraffin. The production process can also be shorter and cheaper than that of concrete since WEP resin cures very quickly in the air.
- Harsh Environmental Resistance: WEP is completely inert. It doesn’t break down and it resists damage from exposure to water, weathering, and harsh chemicals. It is highly durable and can hold up to the toughest working environments. This is a significant advantage over concrete, which has limited chemical resistance properties. WEP is also fire-retardant (although best-suited for normal operating temperatures).
- Easy Preparation: WEP resin is formed through a simple process of mixing and curing, which means it is easy and fast to prepare, which saves time and money.
- Void-Free Curing: WEP resin sets cleanly and with minimal imperfections and no odor. It cures as a contiguous solid material with no voids, holes, or bubbles. This keeps performance high and production costs low.
- Reusable: When kept intact as originally manufactured, shipping containers and shielding walls containing WEP can be reused.
The team at Frontier is happy to answer further questions about how WEP resin compares to other options.
WEP in Frontier Technology Corporation Neutron Shielding Products
Neutron emissions are a serious threat in many industries. WEP resin offers a versatile and cost-effective way to mitigate that risk and protect employees.
Since 1987 we at Frontier Technology Corporation have been world leaders in neutron source fabrication and shipping. We apply our expertise in shielding logistics to deliver reliable custom shields that meet varied industry challenges. To learn how WEP resin is used in our custom shielding solutions, contact our team today.