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Exploring the Darker Side of Everything

Cobalt Bombs: The Bombs to End the World

In 1957, as the world’s nuclear anxiety began to crank up, Nevil Shute released a fictional book that captured the slow unraveling end of the world and its effect on the community in and around Melbourne. 

The story follows a group of characters as they try to come to terms with a steadily approaching radiation cloud that kills everything in its path. With the rest of the world already gone, either through the quick World War III that erupted or the radiation fallout, the story’s protagonists must struggle with the inevitable, and if possible, even enjoy their last few months before the last flicker of humanity is finally extinguished. 

It is a tale of impending doom and heartbreak quite unlike anything else and thankfully this has never come even remotely close to happening. However, the doomsday weapons that heralded the end of the world in the book are very much a reality – well, a terrifying theoretical reality at least. These are the nuclear bombs that top them all, the gold medal-winning weapons that have the power to bring about the end of days. They are – Cobalt bombs.

Nuclear Weapons 

We tend to just lump all nuclear devices under the same nuclear bomb banner, but there are considerable differences between the many bombs lying around the world that have the power to kill tens of thousands of people – at the minimum. 

The biggest difference, to begin with, is the contrast between nuclear fission and nuclear fusion weapons. With nuclear fission, a heavy atom is split into two lighter ones, while with nuclear fusion, the exact opposite occurs with two lighter atoms fusing to form a heavier one. 

In Layman’s terms, nuclear fission, and the fission products it emits, is more unstable and produces significantly more nuclear fallout and higher levels of radiation. Nuclear fusion, on the other hand, can be far more destructive but is regarded as more stable as it does not create fission products. So in theory, a bigger initial explosion, but less contamination. Although hydrogen bombs, which fall into the fusion category, typically include multi-stages which can include a fission stage. So if you’re a sadistic megalomaniac hell-bent on destroying the world, you can have the best of both worlds.

Salted Bombs

I do hope the title of this section puts an image of somebody carefully salting a nuclear bomb before launch, but alas this has nothing to do with the white seasoning we’re all so fond of. If it was possible to take an even darker turn from nuclear weapons, salted bombs would be it. These are essentially nuclear weapons that have been specifically designed as a radiological weapon, producing enhanced quantities of radioactive fallout, leaving an area completely uninhabitable for a long period. 

The use of the word salt comes from the expression ‘salting the earth’ which was a ritual of spreading salt over the destroyed remains of cities as a way of cursing its reinhabitation. This was a widespread practice in the ancient Near East and the story goes that the Romans ploughed salt into the ground over the ashes of Carthage after they had obliterated the once great city in 146 BC.  

The concept in conjunction with nuclear weapons was first discussed by Hungarian-American physicist Leo Szilard in 1950. He was far from a globe destroying kind of person and spent the last years of his life campaigning passionately against the use of salted nuclear weapons. 

As far as we know, a large-scale salted nuclear bomb has never been built, but the theory behind it has been clear for some time. A salted bomb could be created using either a fission or fusion nuclear device which is surrounded by a material containing an element, either gold-198, tantalum-182, zinc-65, and cobalt-60, that can be converted to a highly radioactive isotope by neutron bombardment. 

Once the bomb explodes, the element absorbs neutrons released by the nuclear reaction, converting it into its radioactive form and unleashing absolute hell. The result would almost certainly be extreme levels of radiation spread over a wide area that would stick around for a really, really long time. Depending on the element used, you might be looking at over 100 years until an area could be inhabited once again.

These are weapons so awful, so destructive, that even the two giants of the Cold War stayed away from them. Salted bombs go way beyond anything we can imagine, not only would they destroy cities in the initial attack, their effects would slowly spread far and wide, effectively butchering large areas of the planet.     

Cobalt Bombs 

And that brings us to element number 27 on the periodic table, cobalt. A magnetic silver-blue metal that is used to make lithium-ion batteries, powerful magnets and alloys in jet turbines and gas turbine generators, while cobalt salts have been used for centuries to make the colour blue in paint, porcelain, glass, pottery and enamels. 

Then we come to the more unstable and certainly fierier isotope Cobalt 60, a highly radioactive cobalt spin-off that is used to fight cancer, something that Leo Szilard discovered in the late 1950s and even used on himself after his own cancer diagnoses. It certainly has some noble usages, but used in the wrong way, and it could be used to create an unimaginably horrible new breed of nuclear weapons. 

The wonderful irony of this adaptive, yet terrifying element is that it is an essential trace element, meaning that humans need it to live. OK, we don’t need much and a typical human body only contains around 1 milligram, but it does form part of the active site of vitamin B12, which is very important to us. 

As far as we can tell – although bear in mind my nuclear physicist’s badge is a little out of date – building a cobalt bomb wouldn’t be too difficult, providing you have huge amounts of cobalt at hand. All you would need is a standard hydrogen bomb that you would then surround with large quantities of Cobalt 59 – not Cobalt 58, not Cobalt 60, only Cobalt 59. 

Once the bomb detonates, the neutrons produced would transmute the cobalt to the radioactive cobalt-60, all of which would be vaporized during the explosion. This sounds like a good thing, but actually, the cobalt would then condense and slowly drift back down to earth where it would contaminate everything around it. 


While no large-scale cobalt bombs have ever emerged – famous last word there – the world has seen at least two fairly small-scale tests that have involved cobalt in one way or another, first by the British in the 1950s and then by the Soviets in the 1970s. 

The British test took place on 14th September 1957 at the Tadje site in the Maralinga range in Australia and used small cobalt-60 pellets as a tracer for determining yield. The bomb used had a blast yield of 1.5 kilotons of TNT and a cloud that rose to 2,900 metres (9,500 ft) spraying cobalt pellets over a wide area. Quite astonishingly, hardly any personnel had been informed about the inclusion of the pellets leading to several instances of people picking up the strange objects and suffering mild radiation poisoning as a result. The test was generally considered a failure and that was the last time the British ever played around with cobalt. 

A Soviet nuclear test in 1971 produced high amounts of cobalt-60 from the steel that surrounded the nuclear devices but as far as we can tell, this doesn’t appear to have been on purpose and despite high levels of radiation being emitted, it’s thought that plant life has returned to the area since.   

The Fallout

Now, remember that cobalt bombs are not all about their initial physical destructive power, but rather what comes next. There are numerous factors to consider here, the quantity of cobalt, the percentage conversion of cobalt 59 into cobalt 60, the presence of wind etc, but in theory, a single large-scale cobalt bomb could effectively end humanity – if a few factors went the right way. 

If a nuclear weapon was dropped containing 510 tons of cobalt, it could, theoretically at least, distribute 1 gram (0.03 ounces) of cobalt to each square kilometre of the Earth. One gram would probably include around fifty curies (1.85 terabecquerels) of radioactivity, which would irradiate a person with roughly 0.5 gray of ionizing radiation per minute. To give you an idea of just how bad that would be, just 3 or 4 grays (6 to 8 minutes exposed to the worst stuff) would wipe out 50% of the population in just 30 days, with the rest close behind. And remember, that’s with just a tiny amount of exposure time – less time than it would take to hard-boil an egg to be exact.   

However, that’s the best or worst-case scenario, depending on how you want to look at things. 

The likelihood would be that the fallout would not distribute evenly, leaving some areas heavily radioactive and others not. Whether small patches with low enough radiation for humans to survive might remain isn’t exactly clear. Even if areas did escape the initial fallout, the radioactive isotopes would be strong enough to effectively become part of the natural meteorological cycles – meaning it could rain radioactive cobalt.       

Cobalt 60 typically comes with a half-life of 5.27 years before decaying into Nickel 60. However, that 5.27 years is a little misleading as this simply means that half of the cobalt will have decayed by this point and this just means that you would be able to survive in the area a little longer than before.  

If this initial blast yielded a fallout with the strength of 10 sieverts (Sv) per hour, people would receive a lethal dose in just 30 minutes and 5.27 years later, you could spend a whopping one hour there before your body began crumbling under the effects. 

10 half-lives in – or 53 years to us non-physicists – the dose rate would have reduced further to 10 mSv/hour and a person could spend 4 days in the area with no immediate effects (but would significantly jack up your chances of an array of cancers in the future). Anything longer than 4 days – and by that I mean 4 days and a few hours – you’d start to not feel too good and your days may well be numbered.   

105 years after the explosion and 20 half-lives down, the dose rate would be down to 10 μSv/hour, meaning that people could remain outside full time, but considering this level is still around 30 times higher than normal levels, is likely that the fallout would still cause considerable health damage further down the road. The magic point, where the fallout from a cobalt bomb would become negligible, is thought to be around 130 years – which is a long time to hide away in a bomb shelter.  

Status 6

But this is all something we don’t need to worry about, right? Well…maybe. In 2015, Russian State TV broadcast a video of a meeting between Putin and his military chiefs which “accidentally” revealed plans for a new torpedo known as the ‘oceanic multi-purpose Status-6 system’ when one particular general was seen rather openly holding a piece of paper with details of the new superweapon on it.

The whole thing was a little too convenient for my liking and many have marked this down as simply yet another of Russia’s rather clumsy misinformation attempts to scare those in the west and to raise some much-needed prestige at home. But we probably shouldn’t completely discount it. According to the quick snatches of information afforded to us, the torpedo is designed to have a range of up to 10,000km (6,200 miles) and a depth of trajectory of up to 1,000 metres (3,300ft), though there’s absolutely no mention of cobalt – those rumours seem to have begun afterwards.

Soon after, diagrams began appearing on U.S television showing the potential fallout from a cobalt torpedo strike on Washington D.C and the radiation that spread across the entire country and into both Canada and Mexico. But let’s be honest, this kind of attack would result in such retaliation, it would effectively end life as we know it. Using a cobalt bomb to start a war would be like blowing up your house to fry an egg. Crazy – insane – and probably only as a desperate last resort.   

The Doomsday Device 

In Stanley Kubrick’s 1964 Dr Strangelove, the wider world was introduced to the idea of a doomsday device, a concept that had begun appearing in science-fiction throughout the 1940s and 1950s but that had also gained political interest. 

As you can probably guess, there’s no coming back from the activation of a doomsday device. Once the ball begins rolling on this one, life on earth essentially comes to a halt over a relatively short period. 

There’s no real defined plan for how this would be done, but it’s entirely likely that cobalt bombs would be used. The Soviet Union developed its Dead Hand system (also called Perimetr) which could automatically launch all of the Soviet Intercontinental ballistic missiles at once if U.S nuclear missiles were already inbound.  

And here’s the scary part. It’s thought that at least some of this could be triggered without human input. If that doesn’t sound scarily like Skynet from the Terminator franchise, then I don’t know what does. And to make it all even worse, there are rumours that this system is still active – although the Russians are kind enough to keep it switched off most of the time. 

There’s absolutely no suggestion that cobalt is being used by the Russians with their bombs in the Dead Hand System, but if a nation wanted to create a doomsday device that they could park in a garage somewhere just in case somebody fired a nuclear weapon at them and they wanted to end the world, it would probably include some cobalt.  

The Dirtiest of Dirty Bombs

While cobalt bombs remain very much a theoretical horror show, their destructive potential is clear for everybody to see. But the thing about weapons, and this is the same for primitive rocks, swords, guns and nuclear bombs, is that they can be used to strike an opponent without harming yourself. I know that sounds incredibly obvious, but this may well be where the line has been drawn regarding cobalt bombs. 

Humans have fought and quarrelled for as long as we’ve been around, and while the complete destruction of cities and even groups of people has certainly occurred countless times, we generally stop short of destroying absolutely everything. 

Cobalt bombs may well be too far even for us lunatic humans. It doesn’t matter how much the U.S and Russia loathe and taunt one another, neither side wants to end the world. 

So we’re safe for now. Probably. Maybe. Let’s just see, shall we?   

Cobalt bomb – Wikipedia

Salted bomb – Wikipedia

Soviet Doomsday Device Still Armed and Ready | WIRED

Putin’s ‘Doomsday’ Status 6 More Deadly and Horrific Than Regular Nuke (businessinsider.com)

How large is the fallout area of the biggest cobalt bomb we can build? – LessWrong

Cobalt_bomb (chemeurope.com)

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