Radiationshielding

Radiation shielding, or radiationshielding, is the practice of reducing exposure to ionizing radiation by absorbing, scattering, or otherwise diminishing the intensity of radiation before it reaches people, equipment, or sensitive materials. It covers shielding against alpha, beta, gamma (X-ray), and neutron radiation, with the choice of material and thickness driven by the radiation type, energy, source geometry, and required protection level.

Shielding effectiveness depends on material properties and geometry. Attenuation is described by I = I0 e^{-μx}, where μ is the attenuation coefficient and x is thickness. Shield design often uses areal density (kg/m^2) and metrics such as the half-value layer (HVL) and tenth-value layer (TVL) to compare materials. High-atomic-number (high-Z) materials like lead or tungsten are effective for gamma and X-rays, while concrete provides mass for room shielding and cost efficiency. For neutrons, hydrogen-rich materials (polyethylene, water) slow and absorb neutrons, and additives such as boron or cadmium enhance capture.

Materials and design considerations include weight, cost, space, structural support, heat generation, and potential activation of shielding material. Shielding is planned to comply with safety standards and the ALARA principle (as low as reasonably achievable). In practice, shielding is used in medical imaging rooms, dental X-ray suites, radiography facilities, nuclear reactors, accelerator vaults, and research laboratories.

Limitations include increased weight and volume, potential secondary radiation, and activation. Advances focus on composite materials, modular designs, and optimized layouts to balance protection with practicality.