Although I’ve covered quite a few nuclear technologies over past few years there is one which I haven’t touched upon but he’s regarded as one of the most insidious forms of nuclear weapon, One which was parodied by the mad magazine with the slogan “save buildings, not lives” and on the one hand was called the cleanest nuclear device whilst also being seen as the most inhumane nuclear devices, Namely the neutron bomb.
When it’s proposed deployment was leaked in June 1977 by Walter Pincus of the Washington Post, it created a worldwide outcry that the American Carter administration we’re about to deploy them without a major public announcement.
So, what is a neutron bomb and why did it cause so much controversy at the time, when despite the talk by the military that it was a much needed weapon, was it never actually deployed, and by 2003 all US stocks had been destroyed.
Well firstly the neutron bomb is still just a form of nuclear weapon but to be given its correct title it’s an enhanced radiation weapon or an ERW.
It was created in the 1950s by one of the members of the Manhattan Project, Samuel T Cohen after visiting the Korean War and seeing the similarity between Soeul and Tokyo. He had also seen the devastation created by the bombs dropped on Hiroshima and Nagasaki, and in his mind he decided to create what he called “the most sane and moral weapon ever devised”.
A weapon that would avoid the total devastation and long lasting effects of radiation that the atomic bomb had shown and yet it would still provide the ultimate purpose of war, to kill enemy soldiers in the field.
In 1958 Cohen had been investigating a low yield “clean” nuclear weapon, one which would create a large burst of radiation but without creating the large amount of long lasting radioactive fallout as seen in conventional atomic bombs.
He discovered that the bomb case thickness made a major difference to the amount of radioactive fallout that would be occur. This was because the case of a nuclear weapon which was often made from depleted uranium and was used to reflect neutrons from the nuclear reaction back into the bombs core and increase its reactivity many times, was also the source of most of radioactive fallout.
He figured that if you used a thinner case material, most of the high energy neutrons would escape. This would create a much lower yield with less destructive capability, but it would release 10 to 15 times more neutron output compared to a conventional nuclear weapon.
Neutron bombs were unique in that the neutron radiation would extend beyond the blast radius of the weapon, even the biggest bomb, the 50 megaton Tsar Bomba had a neutron range that was smaller than its blast radius.
He calculated that one kiloton bomb could release more lethal prompt neutron radiation, than a much larger conventional none ERW device .
He justified the use of radiation to kill soldiers because it would have a relatively small blast radius that would do less damage to the surrounding infrastructure as being more humane than using many conventional weapons, such as thermobaric bombs, napalm and cluster munitions.
Although he was convinced in his ideas that this would be an ideal and manageable nuclear weapon that could be used as a tactical device on the battlefield, six presidents came and went before he could convince president Jimmy Carter that this would be a weapon that could counter the overwhelming tank superiority of the Soviet Union, which in the mid 1970s was deemed to be upto a 4 to 1 advantage compared to NATO in the European theatre.
The problem which NATO had in the 1960s and 70s was the Soviet Union had created a huge conventional army with many more tanks and armoured vehicles.
The fear was that a Soviet attack would send in huge amounts of tanks into West Germany in tight formations making them much more difficult to counter then if they were spread out.
Cohen convinced Carter that this small ERW could be used to intimidate Soviet Union into widening their tank attacks and thus making them more vulnerable to conventional weapons like NATO tanks which were seen as superior and anti tank missiles which NATO had hundreds of thousands of.
If that didn’t work and the conflict was going against NATO, these weapons could be used on with less blast damage and residual fallout then a conventional nuclear device and that they will be small enough but they might not trigger a full scale nuclear retaliation from the Soviets.
The idea was that they will be detonated above the massed ranks of Soviet armour and that intense burst of neutron radiation would produce an almost instant incapacitation of the crews inside any unprepared armoured vehicles and troops on the ground within about 1 kilometre range. This was seen as a deterrent that would minimise civilian casualties as it would be restricted to military targets and kept away from civilian areas
But of course this was still a nuclear device, and although it was much smaller than the one dropped on Hiroshima, one kiloton compared to 15 kilotons, it’s still produced a blast radius of about 500 metres, and because it had much less radioactive fallout, Cohen said that it was a “clean” weapon that would leave the area it had been detonated over able to be used within a few days or less by what was hoped to be NATO troops.
This idea of using a tactical nuclear weapon against the much larger numbers of conventional armour of the Soviets was seen by many in the military and in the political leadership of the West as one of the triggers that could then bring about an allout nuclear war, one to be avoided as much as possible unless there were no other alternative.
The use of these enhanced radiation weapons were put into practise in the late 50s and 60s as part of an anti-ballistic missile systems used both by the US and the Soviets.
Here, high speed anti-ballistic missiles such as the Sprint missile, would be fired into the path of the incoming ICBM’s and detonated within a 100 metres of them. The high energy neutron burst given off would cause a partial fission of the incoming warhead and also damage the electronics, with the hope of effectively disabling the weapon.
Approximately 120 of these neutron bomb armed missiles were built, and about 70 entered service from 1975 to 1976 as part of the Safeguard Anti ballistic missile programme until it was shut down and eventually decommissioned in the early 1980s as part of the strategic arms limitation or SALT talks.
The Soviets also used this type of device as the last layer of their anti-ballistic missile defence over Moscow to protect it against a western attack.
But how clean and humane were the claims of Cohen about the neutron bombs.
The primary method of destruction was an intense burst of neutron radiation which would be effective against any organic materials, basically anything that was alive in the radiation blast radius.
Atoms are made-up of positively charged protons, Negatively charged electrons and neutrons which carry no charge.
When a fission reaction occurs in materials like uranium 235 or plutonium 239, these large unstable atoms split apart when they’re hit by a neutron.
This causes new isotopes to be created and a lot of energy in the form of heat, gamma and Xrays and the release of two to three more neutrons which can then go on and hit other uranium or plutonium atoms, in an exponential chain reaction which only stops when the material itself is blown apart by the heat of the reaction.
The neutrons released are fast or prompt neutrons usually in the 13 to 14 mega electron volt range. This means that when they hit Protons in the atoms of living cells especially hydrogen atoms in water and fat cells, they can recoil a proton forward at high speed, and because the proton is a charged particle it dumps its energy very densely causing intense ionisation paths within the cell.
This causes complex DNA damage like breaking it up into smaller strands and leaving clustered lesions, it also damages cell structures and membranes and causes cell death or the loss of function.
This high energy neutron radiation can also create secondary radiation which gives off gamma rays and other energetic particles would should go on to create further damage inside cells.
There is also another effect cause by neutron radiation which is called “neutron activation”. This is where neutron radiation induces radioactivity into other non-radioactive materials when their atomic nuclei capture the free neutrons becoming heavier and entering an excited state which is unstable. This nucleus then starts to decay immediately by emitting gamma rays or particles such as beta and alpha and fission products.
Basically, what this means is that within the neutron blast radius, other materials especially metals but also including air, water and soil and elements in it can be made radioactive.
Normally these have short half-lives ranging from 7.3 seconds with Nitrogen-16 in Air and water, to 14.96 hours for Sodium-24 in concrete & soil salts but upto 5.27 years for Cobalt-60 in steels and alloys, all of these would all add to the radioactivity in the area.
Although it was said that death would be instant for those close to the detonation with radiation levels of up to 8 grey, for reference 1-2 grey is usually fatal but not instant .
If they were farther way the dose would still be lethal but the effects of acute radiation syndrome could take days or weeks before death finally occurred as the body can no longer replaced damaged cells, basically a slow painfully and very inhuman end. If you have ever seen the dramatized TV series Chernobyl, you will have seen the effect is has.
Now these were under Ideal conditions, however in the real world things would be different. The Soviets knew these weapons could be used and it doesn’t actually take much to add enough protection to mitigate most the extra neutron radiation.
The air itself provides absorption this is why the range is only about 1 kilometre beyond that it drops off rapidly. Also armoured vehicles could be fitted with extra materials with a high hydrogen content such as water, plastics & polyethylene or boron carbide, borated steel, or wax. This could drop the neutron levels in the vehicles to where it no longer incapacitates the crew.
Then there is the issue that if such attack were to occur, there would be thousands of vehicles, and they only have to be spread out a bit more and you would need hundreds of neutron bombs covering approximately 1 square kilometre each to mount an effective defence.
Even though they have a much smaller blast radius and fallout levels, detonating dozens or hundreds of neutron bombs in a relatively small area would probably be worse than using conventional nuclear weapons. And as it would be on home soil, any collateral damage would be against German civilians, not soviets.
But the most obvious thing was that to use any form of tactical nuclear weapon, be it conventional or ERW would more than likely trigger a corresponding response from the Soviets, and before you know where you are you’re into a full scale nuclear war.
Although Jimmy Carter’s administration, said they would adopt the neutron bomb they put it on hold and didn’t actually build any. It would be Ronald Reagan’s administration which actually built them and put them into production with approximately 700 ERW devices in the 1980s, in the form of the W70 Mod 3 lance missile and the W79 Mod 0, 8 inch artillery shell.
However, due to extreme political pressure from Europe where these devices would ultimately be used, they were not deployed and instead stockpiled in the United States.
During the mid to late 80s superior high precision conventional anti-tank weaponry like the A10 warthog and advanced anti-tank missiles made the neutron weapons obsolete by the 1990s.
The last of the W70 warheads for the Lance missiles were dismantled in 1996 and W79 artillery shells were fully disposed of by 2003.
Other countries also developed ERW weapons, including France and China but again both only developed the weapons but didn’t deploy them, instead they saw them as a technology reserve that could be a called up if required at some time in the future.
The soviets did make their own versions and after the fall of the USSR, its successor Russia in the 1990s and 2000s worked with the US to destroy approximately 25,000 weapons, but due to the fractured nature of the Soviet breakup its not known if all the now Russian ERW weapons were destroyed but if they did survive and have not been maintained its unlikely that they would still work.
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