There have been many discussions about Russia’s threat to use tactical nuclear weapons in its war against Ukraine.
Russia is estimated to possess thousands of tactical nuclear weapons – perhaps the largest stockpile in the world – which could be deployed at any time. The use of nuclear weapons is also entrenched in Russian military doctrine. Ukrainian President Volodymyr Zelensky called on the rest of the world to take the threat seriously.
Here’s what would happen in a tactical detonation of a nuclear bomb, including the three stages of ignition, explosion and radioactive fallout – and how one could survive it.
You see a sudden flash in the sky, as bright (or even brighter) than the sun. You quickly turn your face away and run for cover.
The brightness suddenly disappears, but returns soon after and continues – the distinctive double flash caused by the competition between the fireball and the shockwave. It gets incredibly warm and bright, and you protect your eyes to avoid retinal burns.
The intense heat radiation also causes skin burns, possibly through your clothing. Wearing light colored clothes or being indoors will help.
You have also received substantial doses of invisible nuclear radiation: gamma rays, x-rays and neutrons. You find a blanket to protect the worst from heat and radiation.
You have now survived the first few seconds of a nuclear detonation, hopefully a “tactical” bomb smaller than Hiroshima (which was equivalent to 15 kilotons of TNT).
The fact that you have lived this long means that you are on the periphery, not ground zero. But to survive the next few seconds, there are a few things you’ll need to do.
The shock wave
Then comes the shock wave. This consists of an overpressure shock wave followed by an outward blast wind, often with reverse winds returning to ground zero.
This will destroy or damage all structures built within a certain radius of the epicenter, depending on the yield and height of the burst.
For example, a 15 kiloton bomb would have a fireball radius of about 100 meters and cause complete destruction up to 1.6 kilometers around the epicenter.
A one-kiloton bomb – similar to the 2020 ammonium nitrate explosion in the Lebanese capital Beirut – would have a fireball radius of around 50 metres, with severe damage at around 400 metres.
The shock wave travels faster than the speed of sound (about 343 meters per second). So if you’re a kilometer from the epicenter, you have less than three seconds to take cover. If you are five kilometers away, you have less than 15 seconds.
You will need to protect yourself from thermal and nuclear radiation, as you could die if exposed to it. However, you need to find a safe place – you don’t want to be crushed into a building destroyed by the shock wave.
Go inside, and preferably in a bunker or reinforced basement. If you are in a brick or concrete house with no basement, find a solid part of the building. In Australia, this would be a small downstairs bathroom or utility room with brick walls.
The incoming shock wave will reflect off the inner walls, overlapping the original to double the pressure. Avoid the explosion side of the building and be sure to lie down rather than standing.
If there is no reinforced room, you can lie under a sturdy table or beside (not under) a bed or sofa. You could be crushed under a bed or sofa if a concrete slab collapses.
Stay away from doors, tall furniture, and windows, as they will likely break. If the walls collapse, you’ll have a chance of surviving in a pocket in the rubble.
If you are in an apartment building, run to the fire stairs located in the heart of the building structure.
Avoid timber, fiber cement or prefabricated structures (which include most modern housing in Australia) as they are unlikely to survive. And open your jaw as the breath passes, so that your eardrums receive the pressure wave from both sides.
The third stage is fallout: a cloud of toxic radioactive particles from the bomb will be lifted during the explosion and deposited by the wind, contaminating everything in its path. This will continue for hours after the explosion, if not days.
In comparable British and Australian bomb tests at Maralinga, fallout was clearly preserved in the desert along mile-wide tracks, extending 5 to 25 kilometers from ground zero.
You must protect yourself from the fallout or you will have a short life.
If you are in a stable structure like a basement or a fire stairway, you can shelter in place for a few days, if needed. If your building is destroyed, you will need to move to an intact structure nearby.
Block all doors, windows and air gaps. You can drink water from intact pipes and eat from sealed cans.
For travel outside, any PPE available should be used, in particular a P2 mask, or even a dust mask. While tactical nuclear weapons are designed to destroy personnel or infrastructure, they still allow troop movement under cover of explosion. The radiological risk is significant, but should make it possible to survive.
A radiological weapon, on the other hand, will deliberately increase the radiation dose to the point where it becomes lethal.
Once you have found shelter, you will need to decontaminate yourself. This will require a thorough exfoliation of skin, nails and hair, and a change of clean clothes. But any serious burn should be treated first.
Hopefully, the national authorities will now have intervened for relief and medical care.
Robert K. Niven is Associate Professor, Chi-King Lee is Professor of Civil Engineering, Damith Mohotti is Senior Lecturer and Paul Hazell is Professor of Impact Dynamics at the Australian Defense Force Academy. This piece first appeared on The Conversation.