Hiroshima Day: How Can Concrete Structures Protect You From Nuclear Radiation

The atomic bomb, Little Boy, was detonated 580 meters above Hiroshima, Japan during World War II. The bomb was made from 64 kg of highly enriched uranium-235 which is equivalent to 16,000 tons of TNT. Ninety percent of the city was destroyed. At least 80,000 people immediately died from the explosion, some of them leaving shadows on the concrete sidewalks and buildings around them. In the next few weeks and months, tens of thousands died due to radiation exposure.

As the time passed, most of the shadows etched into the concrete of Hiroshima weathered away. Several of the nuclear shadows have been preserved and moved to the Hiroshima Peace Memorial Museum, a reminder of the harmful effects of nuclear radiation. 

After the war, subsequent research and tests were conducted to improve public awareness and safety in case of a nuclear fallout. According to the American Nuclear Society, in the event of a nuclear attack, the three general guidelines for controlling exposure to radiation are as follows: 

1. minimizing exposure time
2. maximizing distance from the radiation source
3. having a shield 

DID YOU KNOW? 

Concrete is considered to be a good shielding mechanism against radiation from nuclear bombs. In the event of a nuclear attack, survivors of the blast should be able to find shelter inside concrete buildings. Other than being affordable and widely available, concrete has good shielding properties against neutrons and gamma rays. This is primarily due to its intrinsic water content and high density. It is said that 6.6 ft of concrete can absorb or reduce typical gamma rays by a factor of a billion. This is why concrete is used as a barrier in nuclear facilities and is the recommended building material for fallout shelters since the 1960s.