The Fukushima nuclear reactor accident has increased demand for efficient, non-toxic, and lightweight gamma radiation shielding materials, as its absence caused serious delays in managing the situation, and conventional lead-based shielding materials introduce adverse health and environmental effects. Researchers from the Korea Atomic Energy Research Institute (Kim et al.) have now offered a solution to the problem of how to produce lightweight and reliable garments or sheets for protection against gamma and X-ray radiation. The group has suggested the use of nanotechnology for preparing such materials, as it can greatly enhance both the material properties and the shielding efficiency.
The team constructed a lattice-based MCNP model to simulate the relationship between tungsten particle size and gamma-energy-dependent attenuation. They observed the size effect increases as the gamma energy decreases, while it decreases and disappears all energies higher than ~1 MeV. They also verified this concept experimentally by measuring the gamma attenuation using three different energies (~0.3 MeV to ~1.2 MeV) for both nano- and micro-systems.
More importantly, they developed a simple but efficient preparation method for such materials. In-situ pulverization of micro-tungsten powder with polyethylene powder using high energy ball milling produced nano-tungsten powder, the surface of which is encapsulated by PE. Based on this method, a nano-tungsten/polyethylene dispersed polymer nanocomposite was prepared using a conventional polymer extruding process, which is readily applicable to mass production. The researchers believe that their nano-tungsten-containing products for shielding X-ray and gamma radiation – including a full body apron and a thyroid guard – are the first commercially available.