What is shielding against nuclear radiation?

Answer 1

Shielding involves putting layers of material around a radioactive source (or around something which must be protected from radiation in general) to prevent radiation passing out of or into it.

Shielding normally consists of extremely thick layers of concrete, and sometimes a thinner layer of lead. The concrete is often metres or tens of metres thick; lead is normally only decimetres or metres thick, as it is much more absorbent of radiation.

shielding is generally used around a nuclear reactor to protect outside people or nature from radioactive radiations and even making inside reaction safe from alpha, beta and gamma from outside.

Different nuclear emissions require different kinds of shielding. Of course, thickness can be important, so the thicker the better.

Alpha particles do not penetrate well, so almost anything shields fairly well, even a piece of paper.

Beta particles are a more difficult problem; they are shielded by objects of low density. A piece of aluminum will do for less energetic particles - wood or plastic will usually do for more energetic ones.

Gamma rays (and X-rays, which are not nuclear radiation, but are ionizing) are best shielded by dense, heavy materials, such as lead. A thick layer of concrete is also good.

Neutrons go through almost anything, but they bounce around when they hit the nuclei of atoms. They can also be absorbed by the atoms. Water moderates them, or slows them down, making them less energetic, fairly quickly. Since concrete is full of water, a few feet of it - or even earth - is a good shield.

The other ionizing radiation, which is not nuclear, is ultraviolet light, which is easily shielded with UV blocks and screens.