Civilian Fallout Shelters

Fallout shelters – surviving a nuclear attack?
Civilian shelters are designed to protect their occupants from the initial effects of a nuclear explosion and the radioactive debris, called ‘fallout’, which it produces.

The initial effects include gamma rays produced in the first moments of the explosion, the heat flash and subsequent blast wave.

Gamma rays: Many purpose-built shelters are built underground. A steep or deep entrance helps to shield people from those initial gamma rays, which only travel in straight lines. Shielding designed into the structure of the shelter, such as 1 cm of lead, 6 cm of concrete, or 9 cm of compacted earth, can help to further limit the penetration of gamma rays. The use of multiple layers of shielding materials would further limit their penetration (1).

Flash: Once inside the shelter, with the blast doors closed, the major effects of the heat flash would be mitigated, dependent on distance from the explosion.

Blast: The over-pressure and direct force of the blast wave can collapse buildings. Properly designed blast doors could withstand even close explosions, but at least two exits would be needed to prevent people being trapped inside if an exit was blocked with rubble and other debris.

With steps taken to ensure the shelter was waterproof, the people inside stand a good chance of surviving the initial attack. This is why some nations like Switzerland have prioritised the building of civilian shelters.

Fallout: However, since a good shelter would be sealed (to keep out fallout), and would likely be underground (even if just a shallow trench, covered with earth), the temperature inside could become dangerously hot. A ventilation system is needed to avoid a dangerous buildup of CO2 and circulate cooler air from outside. Consideration needs to be given to if or how that air should be filtered. It would always be safer to bring that air inside through a filter, but that then creates the problem of how to replace contaminate filters when needed. However, even the most dangerous fallout particles are large enough that they would not be easily incorporated into the survivors’ bodies. And exposure to that fine dust would still be less hazardous than exposure to the fallout outside of the shelter (1).

Above-ground shelters
The walls and roofs of shelters within buildings need to be both strong and dense enough to withstand the effects of gamma rays, flash and blast. The blast-effects can be formidable and an effective shelter would need to be in the middle floors of smaller buildings, as low as possible, without windows and away from the outer walls (which could collapse). Buildings with more than 10 storeys would need a below-ground shelter. level for most buildings which have more than 10 floors.

People would need to stay inside the shelter for between 2 – 5 weeks.

Water would probably be the most important resource needed in a shelter. Ideally, each person inside would have access to about 1-2 gallons per day. Around 50 gallons per person would be needed, so Bulk storage would be more efficient than using small bottles.

Each person would need enough food to survive inside for that 3 – 5 weeks.

A battery powered radio would also be helpful for receiving emergency announcements, if government broadcast equipment had survived the electromagnetic pulse from the explosion.

Some bedding, sanitary equipment and basic medical supplies would also be needed.

The civil defence manual ‘Nuclear War Survival Skills(2) described the minimum supplies that should be included in a shelter:

  • one or more shovels,
  • one or two Kearny fallout meters (and the knowledge to operate them),
  • at least a 2-week supply of compact, nonperishable food,
  • an efficient portable stove,
  • wooden matches in a waterproof container,
  • a hose-vented 5-gallon can, with heavy plastic bags for liners (the toilet),
  • any special medications needed by family members,
  • a first-aid kit,
  • long-burning candles, sufficient for at least 14 nights,
  • an oil lamp, as well as a torch and extra batteries.

And then you would wait, day after day, perhaps mostly in darkness, waiting to leave your hot, stuffy, low-ceilinged basement shelter to see what remained outside (3).

2 – 5 weeks later
When the levels of radiation from fallout had reduced to safer levels, you would then emerge from the shelter progress to work. Nearby fallout should be washed or swept into shallow trenches in order to further decontaminate the area.

Work outside might be limited to around four hours a day after 3 weeks. If you had it in your medical kit, you could take potassium iodide to limit the uptake of radioactive iodine (released by fallout) by your thyroid gland (1). Your clothes would pick up a lot of fallout. They would need to be changed often, and the contaminated clothes disposed of in plastic bags as far away as possible (4).

You would have to be prepared to sleep in the shelter for months, waiting for help or evacuation, if that was to ever come.

Would a shelter have saved you if the Cold War had turned Hot?

Probably not.

Even if you had a 10 – 15 minute warning, would you have been able to reach a shelter before the gamma blast killed you?

If your civilian shelter was inside the ‘severe damage zone’ (within kilometres of the blast) it would very likely have been destroyed by the heat and blast wave.

In any case, the likelihood was that a full-scale nuclear attack would have happened, not just a limited number of bombs. A target area would likely have been totally obliterated.

And if you did survive the initial attack, in a total war scenario, the skies overhead would have darkened with soot from the fires caused by the heat flashes. It would be cold and a nuclear winter would have been settling in.

In the final analysis, government discussions about fallout shelters and ‘surviving the bomb’ were simply a way to deceive the general public with the hope of survival. Most of us would have died.


1 – “Fallout shelter” –

2 – “Nuclear War Survival Skills” –

3 – “Nuclear Fallout Shelters Were Never Going To Work” –

4 – “How to Survive a Nuclear Bomb” –

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