While an underground shelter covered by 1 meter (3 feet) or more of earth provides the best protection against fallout radiation, the following unoccupied structures (in order listed) offer the next best protection: Caves and tunnels covered by more than 1 meter (3 feet) of earth.
Packed earth insulates against radiation and blast waves, but don't go deeper than 10 feet; if your exits (make two) become blocked in the blast, you may need to dig yourself out.
It depends on the type radiation. Alpha rays only travel around a foot in just air before “dying” - so no penetration into the ground. Beta rays will travel a little further but probably will be stopped within a few inches of earth. Gamma rays can travel further still, maybe 10 feet or so.
A quantity known as the halving-thicknesses is used to calculate this. For example, a practical shield in a fallout shelter with ten halving-thicknesses of packed dirt, which is roughly 115 cm (3 ft 9 in), reduces gamma rays to 1/1024 of their original intensity (i.e. 2−10).
The most reliable shelter is the basement. Underground shelters can protect not only from radiation, but also from debris and blast waves.
The resulting inferno, and the blast wave that follows, instantly kill people directly in their path. But a new study finds that some people two to seven miles away could survive—if they're lucky enough to find just the right kind of shelter.
Fallout radiation decays relatively quickly with time. Most areas become fairly safe for travel and decontamination after three to five weeks.
Gamma rays have so much penetrating power that several inches of a dense material like lead, or even a few feet of concrete may be required to stop them.
Shielding: Barriers of lead, concrete, or water provide protection from penetrating gamma rays.
Each layer of sandbags reduces the gamma radiation by a factor of two. Wetting the sandbags enhances the neutron radiation shielding and protects the sandbags from thermal damage.
A brick building provides better protection from radiation than does a brick veneer building, which is better than that of a frame building. Less radiation exposure (increasing the Protection Factor) is seen at interior locations and below ground.
The walls of your home can block much of the harmful radiation. Because radioactive materials become weaker over time, staying inside for at least 24 hours can protect you and your family until it is safe to leave the area. Getting inside of a building and staying there is called “sheltering in place.”
How large an area was affected by the radioactive fallout? Some 150,000 square kilometres in Belarus, Russia and Ukraine are contaminated and stretch northward of the plant site as far as 500 kilometres. An area spanning 30 kilometres around the plant is considered the “exclusion zone” and is essentially uninhabited.
Bottom line — if you see a nuclear explosion on the horizon, move to the back of the building you're in and stay as far away from doors, windows, and hallways as possible.
Seek shelter indoors, preferably underground and in a brick or concrete building, per the Red Cross and FEMA. Go as far underground as possible, per the Red Cross and FEMA. If that's not possible, try to stay in the center of the building, for example in a stairwell.
At a distance of 20-25 miles downwind, a lethal radiation dose (600 rads) would be accumulated by a person who did not find shelter within 25 minutes after the time the fallout began. At a distance of 40-45 miles, a person would have at most 3 hours after the fallout began to find shelter.
Beta particles travel appreciable distances in air, but can be reduced or stopped by a layer of clothing, thin sheet of plastic or a thin sheet of aluminum foil. Several feet of concrete or a thin sheet of a few inches of lead may be required to stop the more energetic gamma rays.
Shielding: Barriers of lead, concrete, or water provide protection from penetrating radiation such as gamma rays and neutrons. This is why certain radioactive materials are stored under water or in concrete or lead-lined rooms, and why dentists place a lead blanket on patients receiving x-rays of their teeth.
Lead: The Go-To Material for X-rays and Gamma Rays
Other key features include its significant flexibility, exceptional stability, and high atomic number. Finally, lead is available in a variety of forms, which makes it the best choice for shielding x-rays and gamma rays.
Different materials have different properties that affect their ability to attenuate or reduce the intensity of radiation. Concrete is one of the most common and versatile materials used for radiation shielding, but it also has some advantages and disadvantages that you should be aware of.
Usually, concrete is used as a radiation shielding material. It is a popular building material because it is cheap, strong, and easily moldable. It is common for radiation shielding because of its high density and water content, making it a good barrier against radiation such as gamma rays.
The barite concrete is preferred materials against radiation. Mortazavi et al. [13] studied the shielding property of galena concrete (density = 4.8 g/cm3).
Natural radiation is a normal part of the environment that emanates from two main sources: cosmic radiation, which originates in outer space and passes through the atmosphere, and the decay of radionuclides (radioactive isotopes or radioisotopes) in the soil and rock.
Soils are porous materials with high shielding capability to attenuate gamma and X-rays. The disposal of radionuclides throughout the soil profile can expose the living organisms to ionizing radiation.
From the exposure rate determined by a survey instrument, future exposure rates may be predicted from a basic rule known as the "7:10 Rule of Thumb." The 7:10 Rule of Thumb states that for every 7-fold increase in time after detonation, there is a 10-fold decrease in the exposure rate, where the rate is the same unit ...