Living in caves helped prevent radiation leakage

To Prehistoric humans, a natural cave ticked every box to their survivalist brains. It kept them sheltered against the elements, it had a natural choke-point to fend off predators or opposing tribes, was difficult to enter, and had insulation against temperature fluctuations.

A cave is a natural fortress, practically impossible to destroy through conventional means, with multiple feet of solid stone between the inside and the outside. Throughout history caves and dug outs serve as either homes, or storage simply due to the sheer fact that it is a cave, and the inherent sturdiness that comes with it.

Across history caves have served as shelter, with them serving as a reference point to how we ourselves dig underground, and how we use that underground space. Root cellars are dug out pits, dark, cool and dry that keeps food preserved for long periods of time. Basements in houses are safe places when there are natural disaster.

When someone is trying to keep something safe, or even hide it from someone, they bury it underground, under layers of stone and soil. By the time of the first world war, the majority of nations use bunkers and trenches to protect their borders, using concrete and dirt to form impenetrable fortresses dug into the earth. These held large stores of food, water, ammunition, and more.

Fortresses dug into the earth are practically impenetrable by conventional means. During the battle of Verdun, the French Fort Vaux withstood alone for over a week against prolonged German attack and bombardment, only being captured due to ammunition and water completely running out. It’s concrete walls withheld another six months of combat, and after it’s recapture by the French was the fort repaired to pre-battle conditions.

To engineers and radiation workers, they needed a place to store highly volatile radioactive waste, and they turned to underground storage. Cave systems solve many of the problems with storing radioactive waste long term, they are difficult to enter, meaning very little chance of people stumbling upon the waste. Stone is also very dense, absorbing radioactive particles and x-rays before they can endanger someone. They are also extremely sturdy, with very little chance of a containment breach when surrounded by solid rock and reinforced concrete.

Radioactive particles do not travel far in very dense substances, often being stored in thick concrete or deep water pools. Water is very good at cooling off radioactive substances, but is not ideal for long term storage with it’s overall temperature requiring specific conditions to stay as a liquid. Concrete on the other hand, similar to stone, is very dense, and will not change based on the temperature or condition it is in.

A waste facility serves the same purpose as a cave does, just now for a different, more volatile occupant. It keeps radiation from leaking into the outside world, prevents anyone from easily reaching it, and keeps consistent temperature to let the radioactive material rest in peace.

References:

https://www.stumpcrosscaverns.co.uk/how-our-ancient-ancestors-used-caves

https://en.wikipedia.org/wiki/Cave_dweller

https://www.cheminsdememoire.gouv.fr/en/fort-de-vaux

https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-waste/storage-and-disposal-of-radioactive-waste