Freedom From Nuclear Fear I: 1950– The Idea Of The Cobalt Bomb

A guest article by Joseph Friedlander

This is an longer article giving cold war history. The conviction that nuclear war would end all life on Earth has its source in a single radio conversation in 1950.  This is about that conversation and its’ historical context.

  In the second part of this post,  Freedom From Nuclear Fear II: The 1964 Consensus,  I advance the idea that the tension built up in this article was coiled like a tightly wound spring in many psyches, and the Cuban Missile crisis gave a horrible example of how a nuclear war could and probably would happen if things went on the way they were going.  The civilian anti-nuclear movement happened, in this hypothesis, after  the real military danger was over, in kind of imitation of a silent revolt led by scientists who believed the world was in serious danger and something needed to be done. Do I have proof of this? No. Just reading between the lines of many many old articles and accounts.  But it would account for the sudden change in the world’s direction after 1962.

 If you ever saw On The Beach,

Freeman Dyson’s review of On The Beach:

This nightmare produced a literary response which has continued to reverberate ever since. In 1957, only two years before his death, the novelist Nevil Shute Norway published On the Beach, a description of mankind wiped out by radiological warfare. Norway’s poignant translation of apocalyptic disaster into the everyday voices of real people caught the imagination of the world. His book became an international best-seller and was made into a successful film. 
The book and the film created an enduring myth, a myth which entered consciously or subconsciously into all subsequent thinking about nuclear war. The myth pictures nuclear war as silent inexorable death from which there is no escape, radioactive cobalt sweeping slowly down the sky from the northern to the southern hemisphere. The people in Australia, after the rest of the world is dead, live out their lives quietly and bravely to the end. There is no hope of survival; there is no talk of building an underground Noah’s Ark to keep earth’s creatures alive until the cobalt should have decayed. Twenty-five years before Jonathan Schell, Nevil Shute imagined the human species calmly acquiescing in its own extinction.
The myth of On the Beach, like Jonathan Schell’s myth, is technically  flawed in many ways. Almost all the details are wrong: radioactive cobalt would not substantially increase the lethality of large hydrogen bombs; fallout would not descend uniformly over large areas but would fall sporadically in space and time; people could protect themselves from the radioactivity by sheltering under a few feet of dirt; and the war is supposed to happen in 1961, too soon for even the most malevolent country to have acquired the megaton-nage needed to give a lethal dose of radiation to the entire earth. Nevertheless, the myth did what Norway intended it to do. On the fundamental human level, in spite of all the technical inaccuracies, it spoke truth. It told the world, in language that everyone could understand, that nuclear war means death. And the world listened.  

if you ever  read other apocalyptic nuclear war novels

if you ever saw any discussion of what happens if nuclear war ends life on the Earth, despite the fact that actually deployed arsenals would do no such thing

 you are basically listening to a faint, faint echo of a single conversation that happened early in 1950 after President Truman ordered the development of the hydrogen bomb.

This is the actual text of Truman’s announcement:
Statement by the President on the Hydrogen Bomb   

January 31, 1950 

IT IS part of my responsibility as Commander in Chief of the Armed Forces to see to it that our country is able to defend itself against any possible aggressor. Accordingly, I have directed the Atomic Energy Commission to continue its work on all forms of atomic weapons, including the so-called hydrogen or superbomb. Like all other work in the field of atomic weapons, it is being and will be carried forward on a basis consistent with the overall objectives of our program for peace and security.

This we shall continue to do until a satisfactory plan for international control of atomic energy is achieved. We shall also continue to examine all those factors that affect our program

Provided courtesy of The American Presidency Project.  John Woolley and Gerhard Peters. University of California, Santa Barbara. 


Shortly thereafter there was a University of Chicago Roundtable talk in Feb. 1950. 
This caused an uproar and controversy.

 referred to in this abstract: From October 1950

AUTHOR(S)Arnold, James R.

PUB. DATE October 1950
SOURCE   Bulletin of the Atomic Scientists; Oct 1950, Vol. 6 Issue 10, p 290
DOC. TYPEArticle
ABSTRACT  The article discusses the properties of the hydrogen-cobalt bomb. On a University of Chicago Round Table broadcast, Dr. Leo Szilard announced that the hydrogen bomb could be rigged to disperse lethal radioactive dust throughout the earth. Szilard stated that the weapon of mass destruction can be achieved through the production of the necessary deuterium. If produced, the amount of deuterium can be exploded, in which about fifty tons of neutrons will be produced. The neurons may be absorbed in an element, which may result to a dangerous radioactive isotope. The radioactivity produced could irradiate every human being intensely enough to cause death. An evaluation on the danger posed by the said bomb is presented.
ACCESSION #21318626

A link to a picture of the article in Bulletin of the Atomic Scientists Oct 1950  article   reacting to and critiquing Dr. Leo Szilard’s statement;

The above  Bulletin of the Atomic Scientists Oct 1950  article in Google Books

A brief summary of the key points of the Bulletin of the Atomic Scientists Oct 1950  article  without quoting all the text:

  1. 500-10000 tons of deuterium could be produced.  (The process listed in the article would not be used today)  The cost today might be around half a million dollars a ton.  Assuming 1000 tons $500 million of deuterium.  The $40 billion 1950 dollar budget is totally unrealistic, about 10 years later many estimates appeared that a doomsday like bomb as outlined here would cost less than the military budget of a small European country for a few years.  As it turned out efficient thermonuclear burns are possible so you don’t need 10000 tons of D, rather merely 500.
  2. We now know a multistage H-bomb will work, can be made of unlimited size this was merely considered probable in the article.
  3.  Deuterium reactions are outlined. Most of the deuterium in the 10000 ton model (95% is assumed dispersed by a massively inefficient burn. Most of the 500 ton model is burned efficiently. Net output includes at least 60 tons of neutrons.
  4. The article estimates that over 3000 tons of cobalt are needed for perfect capture of the neutrons to create cobalt 60- to avoid wastage of neutrons and ‘over capture’ three times this amount might be needed. For comparison only 25000 tons of cobalt or so are typically produced in a year. (a few years old) typically at a price of $25 a kilo. The article does not discuss using the cobalt  in the tamper, probably because that was probably a classified term in 1950.  Less cobalt than 10000 tons might be practical in that case. If 10,000 tons, $250 million of cobalt.
  5. A discussion of shielding effects of the atmosphere. The absorption half thickness for 1.2 mev gamma rays is 8 grams of air or about 60 meters (the atmosphere effectively is 1 kilogram or 10 km thick) A lethal dose if uniformly distributed would then be around 3 months unlimited exposure on the surface.
  6. But the distribution will not be uniform. Doses will vary countermeasures are possible but still the fact of how practical all this is is disturbing to the author.


In the March 1950 Bulletin of the Atomic Scientists Page 75 12 physicists expressed the opinion that “this bomb is no longer a weapon of war but a means of extermination of whole populations… there can be only one justification for our development of the hydrogen bomb and that is to prevent its use.”  They were speaking of the unlimited radiation warfare in prospect then. 

Notice the whole-population extermination meme circulating here. Look at this reference to get a feeling of recent Nazi and Soviet history and understand why in  an increasing number of American eyes the Soviets were now as bad as the Nazis.

 A lot of this stuff was covered up in the war because the Soviets were our ally in 1941-45 but in 1950 a lot of stories were coming out.
from Wiki

The maximum territorial extent of countries in the world under Soviet influence, after the Cuban Revolution of 1959 and before the official Sino-Soviet split of 1961 

The eastern hemisphere holdings are complete from 1950.

How the Soviet Elite was regarded in the Bulletin of the Atomic Scientists march 1951  Page 77

In 1950 p 169 Bulletin of the Atomic Scientists Jun 1950 Winston Churchill on the Communists prepping hit lists of people for the NKVD to off in case of a Soviet occupation of Western Europe

If you ever read Not This AugustNot this august.jpg

 by Cyril Kornbluth you will understand the inference that if America were ever occupied such targeting was in prospect for many Americans who thus felt personally threatened. The news about the Katyn Forest Massacre had come out and remember Joseph Stalin, who had authorized that, was still the dictator of the Soviet Union.  A congressional committee did not fix blame on the Soviets until after 1951 but those who distrusted the Soviets correctly as it turned out suspected they gained the most from killing the Polish elite.

Wiki on the Katyn Forest Massacre
The prisoners assumed that they would be released soon, but the interviews were in effect a selection process to determine who would live and who would die. According to NKVD reports, if the prisoners could not be induced to adopt a pro-Soviet attitude, they were declared “hardened and uncompromising enemies of Soviet authority”

On 5 March 1940, pursuant to a note to Joseph Stalin from Beria, six members of the Soviet Politburo—….—signed an order to execute 25,700 Polish “nationalists and counterrevolutionaries” kept at camps and prisons in occupied western Ukraine and Belarus.

The reason for the massacre, according to historian Gerhard Weinberg, was that Stalin wanted to deprive a potential future Polish military of a large portion of its talent:

 … A more likely explanation is that … [the massacre] should be seen as looking forward to a future in which there might again be a Poland on the Soviet Union’s western border. Since he intended to keep the eastern portion of the country in any case, Stalin could be certain that any revived Poland would be unfriendly. Under those circumstances, depriving it of a large proportion of its military and technical elite would make it weaker.

In addition, the Soviets realized that the prisoners constituted a large body of trained and motivated Poles who would not accept a Fourth Partition of Poland…

In 1951 and 1952, with the Korean War as a background, a U.S. Congressional investigation chaired by Rep. Ray J. Madden and known as the Madden Committee investigated the Katyn massacre. It concluded that the Poles had been killed by the Soviet NKVD and recommended that the Soviets be tried before the International Court of Justice.  However, the question of responsibility still remained controversial in the West as well as behind the Iron Curtain

Eventually the truth came out but to this day many Communists lie like a rug about who did it, despite the Russian government opening the archives.

An independent Australian Polish site about the massacre.

 You can read the Wiki account for more but the point was: If the Communists took over your country and the NKVD (or their successor, MVD) knocked on your door at 4 AM you would have a very good chance to die or spend the remaining short years of your life in utter misery.  Many people were determined to use any amount of force needed to make sure that never happened.

In just over a decade the line of what was acceptable to do against cities in warfare had flipped around to a mirror image of what was once permissible.

Just 11 years before that FDR was protesting the conventional bombing of civilians.

Now threatening nuclear doom was a defense necessity.
As Brian Baldridge has stated in his classic formulation Once you decide it’s okay to bomb civilians, the weapon used is much less important.
(To be technical about it many people draw the line at the WWI German Zeppelin raids over London and I have no doubt you can find cases dating from before the invention of artillery.)
From Wiki

British recruiting poster from 1915

The actual transcript of the famous cobalt bomb roundtable
The University of Chicago Round Table (February 26, 1950), 623 : 1 – 1 2. “The Facts about the Hydrogen Bomb.” Bulletin of the Atomic Scientists (April 1950), with Leo Szilard  Harrison Brown Frederick Seitz and
Hans Bethe 

is in Bulletin of the Atomic Scientists Apr 1950 issue page 106.

Earlier in the same issue is a famous quote by Hans Bethe on page 102 that however horrific the Soviet system:

“If we fight a war and win it with H-bombs what history will remember is not the ideals we were fighting for but the methods used to accomplish them. These methods will be compared to the warfare of Genghis Khan who ruthlessly killed every last inhabitant of Persia.”  Bethe speaks of a new dark age if we become capable morally of using the hydrogen bomb. Very haunting article.

Page 106 begins the transcript; I am only giving the key part here from pages 107-8. You can read the rest at the link.

Bethe: …If H-bombs are exploded in some number then the air will be poisoned by this carbon-14 for five thousand years. It may well be that the number of H-bombs will be so large that this will make life impossible.

Szilard:  Yes, that is true Bethe. But that is not what I had in mind because it would take a very large number of bombs before life would be in danger from ordinary H-bombs.

What I had in mind is this: The H-bomb, as it would be made, would not cause greater radioactivity than that which is due to the carbon; but it is very easy to rig an H-bomb on purpose so that it should produce very dangerous radioactivity. Most of the naturally occurring elements become radioactive when they absorb neutrons.
All that you have to do is pick a suitable element and arrange it so that the element captures all the neutrons. Then you have a very dangerous situation. I have made a calculation in this connection. Let us assume that we make a radioactive element which will live for five years and that we just let it go in the air. During the following years it will gradually settle out and cover the whole earth with dust. I have asked myself: How many neutrons or how much heavy hydrogen do we have to detonate to kill everybody on earth with this particular method? I come up with about fifty tons of neutrons as being plenty to kill everybody which means about five hundred tons of heavy hydrogen.

Brown: You mean, Szilard, that if you exploded five hundred tons of heavy hydrogen and then permitted those neutrons to be absorbed by another element to produce a radioactive substance, all people on earth could be killed under the circumstances?
Szilard:  If this is a long-lived element which gradually settles out as it will in a few years, forming a dust layer on the surface of the earth, everyone would be killed.
Brown:  You would visualize this then something like the Krakatoa explosion, where you would carry out let us say, one large explosion or a series of smaller ones. The dust goes up into the air and as was the case in that particular explosion, it circled the earth for many, many months and even years, and gradually settled down upon the surface of the earth itself?

Szilard:  I agree with you, and you may ask, of what practical importance is this? Who would want to kill everybody on earth? But I think that it has some practical importance because if either Russia or America produces H-bombs– and it does not take a very large number to do this and rig it in this manner– you could say that both Russia and America can be invincible. Let us suppose that we have a war and let us suppose that we are on the point of winning the war against Russia after a struggle which perhaps lasts ten years.  The Russians can say: “You come no further. You do not invade Europe and you do not drop ordinary atom bombs on us or else we will detonate our H-bombs and kill everybody”…who will take the risk then not to take that threat seriously?… Let us assume that we cannot deliver our H-bombs because they are too big. Then the temptation will be great to rely upon the westerly winds to disperse the radioactivity over Russia or over America…

Friedlander here. The idea sounds plausible enough to be terrifying but I can think of no surer way to get underlings to stage a coup against Dictator X than Dictator X threatening to end all life on Earth—a lot of generals would go home look at their kids playing and go ‘I don’t get paid enough to do this.’   Then something like this would happen.

 Lavrenti Pavlovich Beria was a Georgian, like Stalin, who called him ‘my Himmler’. I – See more at:

Back to the transcript: 

Brown:  …Would you like to express any opinion concerning the relative vulnerability of Russia and the United States? It would seem to me, offhand, that with our whole West Coast exposed to the westerly winds and having the whole Pacific Ocean to operate in, if that kind of thing can be done, we are placed at a considerable disadvantage relative to Russia, in that respect because we have Western Europe to consider.

Friedlander here– Professor Brown is referring to this potential tactic: Russia could detonate heavy gigaton mine submarines in the Pacific but the USA could not kill Russia by the same means in the Atlantic without risking Western Europe. In the novel Tomorrow! (1954)  such a gigaton sub took out Russia to end the war but also killing everything around the Baltic Sea. 

Szilard: This one factor is in favor of the Russians…to know whether it is possible to rely upon the westerly winds in any given situation is difficult. The weather conditions change and have to be taken into account…
it is not only a possibility it is a very serious possibility.

Brown: Then we are faced with the ironical conclusion in this respect that it becomes easier to  kill all people in the world rather than just a part of them.

Szilard: This is definitely so.

Friedlander here again. So thus  in 1950 the idea of the cobalt bomb was born. Also, notice, the idea of the Doomsday Machine was born as well written about a decade later by Herman Kahn and picked up by the movie Dr. Strangelove.

 The idea was the A-bomb would trigger an H-bomb that would irradiate the C-bomb— but they were not sure at that point that the H-bomb would even work. Then in November 1952 on the first of the month the first deuterium bomb  was detonated, proving that it would work and it was quite buildable (not using huge quantities of expensive tritium). It was too heavy for air delivery, though. But it was a real H-bomb.

 Also some called the Mike superbomb the U-bomb because the fusion had obviously (isotopic signature proved it) irradiated and fissioned large amounts of U-238 and exploded it.

Then in August 1953 the Soviets detonated a boosted bomb that used some fusion. This was thought to be a real H-bomb. (The real Soviet H-bomb test came on Nov. 22, 1955)  The USA raced to deploy truly portable lithium bombs (Technically L-bombs if you want to keep the letter games up.  Some years later Sam Cohen invented the N-bomb, the neutron bomb, a 1-10 KT small D-T (Deuterium-Tritium) fusion device triggered by a small fission device. And I believe around the 1980s there was discussion of a blast-optimized nuclear bomb at one of the US weapons laboratories–can’t remember which offhand. Call it the B-Bomb So the alphabet bomb collection includes A-Bombs, B-Bombs, H-bombs, U-bombs, L-bombs, C-bombs and N-bombs.(Also S-bombs for Sodium– see below. .)  Once I wondered where the Silver Age DC comic writers got the various kinds of Kryptonite (Green, Red, Blue, etc) but now I think I know at least the unconscious origins of the Kryptonite spectrum.)

So the 1954 lithium bomb tests made modern H-Bombs air portable and field storable–no cryogenics need apply.. Note that this is simultaneously an L-bomb and a U-bomb and a superbomb but nowadays we just call this a big H-bomb.

These two pictures are from the Castle Bravo radiation contours, the second showing the scale vs. the Eastern USA. Notice a Soviet groundburst on DC with the wrong wind kills New York for free.
Worldwide contours over time– to show how a really big bomb would touch the whole world. Multiply the yield by 10,000 or 1 million and you can see we are in real trouble and remember this just covers the first month of spread… for animated gifs of the process visit the source of these (hat tip Alex Wellerstein

After the 1954 H bomb tests this NY Times article said it was practical to build the dread cobalt bomb– text here.

 By William Laurence. (New York Times, April 7, 1954).

 The article speaks of a H-bomb fusinga ton of deuterium. Such a monster would yield as much as 250 pounds of free neutrons. These would produce 7.5 tons of radioactive cobalt, equal to nearly 5,000,000 pounds of radium.”…
“A cobalt bomb, incorporating a ton of deuterium, according to Prof. Harrison Brown, nuclear chemist at the California Institute of Technology, could be set on a north-south line in the Pacific about a thousand miles west of California. “The radioactive dust,” he said, “would reach California in about a day, and New York in four or five days, killing most life as it traverses the continent.”

“Similarly,” he added, “the Western powers could explode hydrogen cobalt bombs on a north south line about the longitude of Prague that would destroy all life within a strip 1,500 miles wide, extending from Leningrad to Odessa, and 3,000 miles deep, from Prague to the Ural Mountains. Such an attack would produce a ‘scorched earth’ unprecedented in history.”

Friedlander here again. He is talking about a line of bombs not just one possibly 100-1000 or so producing enough fallout to take out all human farming and city life downwind and keep it out for 10-20 half lives. In the case of Cobalt-60 probably over a century to resettle.

  Some of the figures in the above article may need work.  Note that a 1 ton deuterium bomb in the context of this discussion means 1 ton of deuterium net fused–82.4 megatons bomb yield in TNT equivalent.   That is bigger than the Tsar Bomba.

Nuclear weapons Faq D-D fusion equations  author (Carey Sublette)
The important thermonuclear reactions for weapons are given below:
1. D + T -> He-4 + n + 17.588 MeV (n kinetic energy is 14.070 MeV)
2. D + D -> He-3 + n + 3.2689 MeV (n kinetic energy is 2.4497 MeV)
3. D + D -> T + p + 4.0327 MeV
4. He-3 + D -> He-4 + p + 18.353 MeV

The first fuel ever considered for a thermonuclear weapon was pure deuterium (reactions 2 and 3, which are equally likely). This is primarily because deuterium is a relatively easy fuel to burn (compared to most other candidates), is comparatively abundant in nature, and is cheap to produce. In fact, no other fuel has this same combination of desirable properties.
Since the reaction cross section of 1 is some 100 times higher than the combined value of 2 and 3 the tritium is burned as fast as it is produced, contributing most of the energy early in the reaction. Reaction 4, on the other hand, requires temperatures exceeding 200 million K before its cross section becomes large enough to contribute significantly. Whether sufficient temperatures are reached and quantities of He-3 are produced to make 4 a major contributor depends on the combustion efficiency (percentage of fuel burned).

If only reactions 1-3 contribute significantly, corresponding to the combustion of 25% of the deuterium fuel or less, then the energy output is 57 kT/kg. If reaction 4 contributes to the maximum extent, the output is 82.4 kT/kg. The maximum temperature generated by an efficient burn reaches 350 million K.

One ton of deuterium will fission 16 tons of U-238 (or so) which would actually add another ~250 megatons or so of very dirty explosive fission yield. But you can use lead as the tamper to avoid the fission and make cobalt the neutron target instead and it will turn ~4 tons of cobalt-59 to cobalt-60.  (Why about 1/4 the amount? Because it takes a neutron to fission U-238 OR to make cobalt-60– but the output isotope yields only 1/4 the amount per neutron)  

So when they say a 1 ton deuterium bomb they mean such generating 4 tons of radioactive cobalt
 (remember the 500 tons deuterium figure generating 60 tons of neutrons. That is a ratio of 8.33 tons D per ton of neutrons. or put another way per 1 ton of D fused, you get .12 tons neutrons, which is consistent with the claim of “250 pounds of free neutrons. These would produce 7.5 tons of radioactive cobalt”)

 So if the fractions are the same each 1 ton deuterium cobalt bomb is 500/4 or 1/125 of what Szilard was talking about generating– .48 tons or 480 kg of neutrons per ton of D. (–in other words half the D’s weight because what is deuterium but a proton and neutron together in a nucleus?) The reason I have quoted the D-D equations above is to try to get a feel for the input-Deuterium– and the output (if all the equations cycle) Helium.  Plus energy. Plus irradiated cobalt with the 14 mev neutrons.

I am looking for a neutron economy D-D reference but not finding it so just leaving it here for now. My feeling was 4 tons of cobalt per ton of D  They say 7.5 tons.  The basic idea is– D-D fusion (or Li6D fusion) in, neutrons and helium out, irradiated cobalt sprayed everywhere. 

Once you got the idea your enemy might make one it was simple prudence to understand how to design a gigaton — or 10 gigaton device yourself.
Edward Teller, born in what became Soviet-Occupied Hungary, was ever mindful of what the Soviets might do. He outlined a 1,000 megaton (1 gigaton) device called GNOMON (the shadow caster on the sundial) and a 10,000 megaton (10 gigaton) device called SUNDIAL.

As quoted in the link below one annex to the report recommending for the hydrogen bomb protested that the existence of a weapon of this type whose power of destruction is essentially unlimited represents a threat to the future of the human race which is intolerable”  At the same link others said Necessarily such a weapon goes far beyond any military objective and enters the range of very great natural catastrophes”

W.H. Clark, in the Chemical and Thermonuclear Explosives article of the Bulletin of the Atomic Scientists November 1961 issue, Vol. 17, No. 9
page 356, 
about 10 years later, gives this hideous radiation warfare treatment nearly its’ ultimate expression. Clark gives the definitive treatment of the cobalt and sodium bombs in engineering terms This was under 2 years since the movie of On The Beach had made it to theaters. Remember this was around the time of the Tsar Bomba and gigantic tests were about to happen in the atmosphere, the Berlin crises were going on and the Cuban Missile Crisis was under a year away as was the novel FAILSAFE (the 1964 movie of that name was just 3 years away)

Subtle and not so subtle threats of nuclear mobilization and attack were routine events in diplomacy.  Armed thermonuclear bombers were on airborne alert. In fiction New York was being blown up probably every other month.  (One example a classic Twilight Zone episode  So memes of apocalypse were in the air, and memories and resonances of that 1950 conversation were about at their zenith and haunting civilization. 

It discusses the old value of 10000 tons of heavy water, with the new processes  now just a billion 1960 dollars, and concludes that for $5-10 billion 1962 dollars you too could build a Doomsday Machine (actually in the article he later concludes it’s not so easy, see below) .

It appears to be discussing a classical super

 built with heavy water, which many have termed impossible. However to detonate it will take a correctly configured H-bomb, not just an A-bomb, in any case, so we are quibbling.

A brief summary of the key points without quoting all the text: “After making sweeping approximations I arrive at the conclusion that a pipe with thick uranium walls will detonate if it has an inside diamter larger than 3 feet. A pipe with low density walls would have to be 5 or 10 feet in diameter…merely an indication that the minimum size is not unreasonably large.. when a ton of either heavy water or uranium is consumed the energy released is equivalent to 20 megatons of TNT… very expensive substances such as plutonium and tritium…useful for making small expensive explosions as booster to set off large insensitive charges..there is a minimum size at which any particular explosive can be detonated but no maximum…this picture fits the few scraps of official information on H bombs which have been published, notably the cost estimates above.”

Friedlander here. Clark may be wrong on his picture of what goes on in the H-Bomb (quite forgiveable given the time this was written)  but the point of a small H-bomb detonating a larger one is straight secondary-tertiary-quaternary theory.

Clark again “the main charge gets progressively cheaper as the energy release increases, reaching the price of heavy water– $5000 per megaton at about a 10 megaton energy release.”
Friedlander here. $5000 1960 dollars today after 700 % inflation would be  $35,000 per megaton  today.
Clark goes on: Many chemical explosives will burn slowly at atmospheric pressure. Crews handling waste TNT sometimes build a bonfire of TNT blocks in order to warm their hands, though the practice is discouraged by safety officers… (in contrast, thermonuclear fuels burn quickly)  the problem is…cooling by conduction and radiation is very rapid at nuclear fusion temperatures… the enormous rate of heat leakage from a fusion reactor can be tolerated if the “reactor” is a bomb, burning tons of fuel in a few microseconds…heavy water is used by the ton… to produce a large quantity quickly, $50 a lb is a reasonable estimate of the cost.
(Clarke goes on to describe submarine barges mines and other means of moving the gigaton mines)

Clark:  “A heavy water bomb could be made with a boron blanked in which case the only radioactivity produced in the explosion would be the small amount due to the detonator…might be used to raise a tidal wave…assuming scale factors…apply to a large mine containing 1000 tons of heavy water… the mine could be placed in water two miles deep. The wave would be 100 feet high at 200 miles from the center…”


those scale factors don’t really apply–

see here 

 for the story of how Freeman Dyson calculated a gigaton mine would do to the East Coast of the USA what the movie Deep Impact did  by comet strike.  But later studies disproved this possibility as quoted there– “

According to the report, as a result of such a deep-water closed bubble creation and dissipation, “no wave of any consequence will be generated.”

 This article by Clark is interesting because I have read over the years probably 4-6 accounts by people who must have read this same article and then wrote some reference to gigaton devices behind a boron blanket making tidal waves as a fearsome weapon of the future.  But this article appears to be the original  source. Glad to know that’s not possible except right near the blast itself.

But then he goes on to describe a new horror: The Sodium Bomb.

Clark: “a blanket of sodium oxide. Sodium is a rather poor neutron absorber so a thick blanket would be required. This is of little consequence because sodium is very cheap. When one gram of neutrons had been absorbed in sodium the resulting sodium 24 would if distributed over one square mile, deliver nearly a hundred thousand roentgens to a man in the open. The lethal radiation dose is 500 roentgens.  A bomb containing 1000 tons of heavy water will yield about 20 tons of neutrons.  (NOTE 200 tons D) Applying the usual scaling laws the area actually heavily contaminated may be estimated at 200,000 square miles, if one tenth actually reached the ground the average dose would be a million roentgens. This would destroy all animal life including people in an average basement bomb shelter all active vegetation and nearly all seeds. The landscape would be temporarily transformed to lunar desolation….the half life of sodium 24  is 15 hours… (in contrast) a blanket of cobalt around heavy water is the famous cobalt bomb …. since the total radiation dose to be delivered is spread over a longer time it follows that the initial radiation level for cobalt 60 is about 3000 times less than for sodium 24 a man in an area contaminated with enough sodium to give a million roentgens total dose would collapse in 10 minutes. After cobalt fallout yielding the same infinite time dose the initial radiation level would be only 20  roentgens an hour it would take a man a day to accumulate a lethal dose and a week to die…For the present cobalt bombs have no value…killing the enemy by inches is not only inhuman but while dying he may do unpleasant things to whoever caused the fallout.

Clark on ordinary U-238 being blown up by D-D fusion just for making lethal fallout:
“About five tons of uranium fissioned in tests (80 megatons fission or so to that point–Friedlander) have resulted in a gamma radiation dose of 50 milliroentgens plus a strontium 90 bone marrow dose of 10 milliroentgens per year in well watered countries near 40 degrees north latitude. Dosage is less by a factor of 50 in dry countries on the equator. 1000 tons of heavy water would fission 5000 tons of uranium. Fifty such mines would be required to produce any lethal remote fallout. Cobalt bombs are much more effective because the half-life of cobalt is well matched to the residence time of bomb debris in the stratosphere…Long ago Leo Szilard pointed out that only 50 tons of neutrons, obtainable from 2500 tons of heavy water (you saw the original quote above, Clark may be mis- remembering or applying a correction factor he does not explain) would produce enough cobalt-60 to give a dose of 10,000 roentgens over the whole earth. The lethal dose in man, for radiation distributed over a long period of time is thought to be 5000 roentgens but it is not certain that a 10,000 roentgen dose in the open would kill the entire population. (Clarke discusses living in caves, especially keeping kids in there).  The dose required to reliably exterminate the population may be several tens of thousands of roentgens.  The test fallout was distributed with extreme non uniformity though we had no way of knowing in advance that this would happen. If Cobalt 60 fallout should distribute itself in the same way large favored areas would have a radiation level 300 times less than the world average… (to actually build a working doomsday machine, Clark estimates)  will require a few hundred thousand tons of heavy water and an equal amount of cobalt…the indications are that the human race will survive the H-bomb, though it will be a close thing. Until some more efficient process is discovered extermination will require a major effort by one or both great powers, which hopefully will not be forthcoming.”

Freeman Dyson may have read this or not, (especially given the eight ideas in that memo
In 1962, physicist Freeman Dyson wrote a memo discussing eight possible novel weapon systems, all of which looked like they’d be possible in the near future, and outlined the potential military uses and dangers of each. This memo has been declassified, but was never published. 
I have no idea what the other 7 are, George Dyson probably does.)

A science fiction list of planet killer horror tech

Naturally people began to consider how to save themselves from all this. In the early 1960s discussion of building fallout shelters was the rage, the mentioned Twilight Zone episode above centers on them.  In the December 1961  issue of the Bulletin of the Atomic Scientists, page 439

the difficulties of survival in a shelter are discussed (but it assuredly would be even worse without one):
“If fallout from each kiloton of fission yield were spread uniformly over a square mile…the radiation rate would be 2600 roentgens per hour instead of 1200 as previously estimated…it has been estimated that in an air burst a 10 megaton bomb could ignite fires out to 35 miles, the circular area of instant ignition would thus be almost 4,000 square miles…assuming that one were 25 miles from ground zero a two minute exposure to immediate fallout from a 20-megaton bomb would be fatal; within an hour, radioactivity would be of the order of 20,000 roentgens per hour (800 is the fatal dose). After two weeks radioactivity within the 25 mile radius would have decayed to 20 roentgens per hour…complete destruction of houses…five pounds per square inch. A one-megaton weapon produces 10 pounds per square inch two miles from detonation point. Maximum fireball radius is around .7 mile…”

But in the Bulletin of the Atomic Scientists – March 1962 on page 14, Freeman J Dyson explains why he is so very much against fallout and blast shelters in the key nuclear confrontation states (He speaks the the US public about them; his mechanism for speaking the the Soviet public about them, or for  empowering them to do something about it, is not obvious to me) 

Key points of Dyson’s anti-shelter logic:  In essence keeping ahead in a shelter race just enables a bigger arms race until you overwhelm the ability of any innocent bystanders to survive your folly.

Summary of the article: Dyson stayed in the West German city of Munster (umlaut on the U) in summer 1947 destroyed 90 percent two years earlier, so thoroughly that paths rather than streets were how you got around. Civilized life continued despite the devastation. It took two weeks to accept devastation as normal background. In other words people can get used to anything. Dyson mentions this not to minimize thermonuclear war but to emphasize that survival is precious.
Shelters therefore cannot be dismissed as being ineffective and Dyson believes effective shelters can be dangerous.

Dyson analyzes possible nuclear wars.

He calculates a number called the Stockpile which is the quantity of fission energy potentially available for release in a major war if the war didn’t end by the death of the combatants. Dyson tries to estimate the upper limit of the Stockpile potential. (he uses this word not purely for made H-bombs but mined in hand material usable in large radiation warfare D-D fusion devices such as Clark outlined above) 

 Basically this is the amount of uranium mined. Assuming the 235 is extracted and the depleted U-238 is available for fusion triggered fission it all can be built into nuclear explosives so millions of megatons are potentially available by 1970.  Dyson outlines a worse case struggle to the death over time by well sheltered adversaries that results in the Death of Earth.

Dyson names a unit the Beach (after On The Beach, above)  which was later referred to in other studies as the DOE (Death of Earth) reaction. A quantity of fission energy if exploded in the atmosphere sufficient to give lethal dose of radiation to half the worlds inhabitants estimates are 1 million to 10 million megatons.

Dyson estimates the quantity of fission energy delivered to ground targets sufficient to kill essentially all inhabitants by local fallout in absence of bomb shelters as roughly 10,000 megatons. You could call this number DOA (Death of America) or DOR (Death of Russia)  

(I believe from an old chart by Ralph Lapp that you get 98% fatalities in the USA at 20,000 megatons, and the USSR at 50,000 megatons but Dyson has made his point)

Dyson’s argument is that the fallout needed to kill the world is about 100-300 times more than any single nation and this is a safety margin for the human race. But if the superpowers build shelters they will just keep building arms until effectively this safety margin is gone.
 The reference to Herman Kahn’s world with 50,000 buttons in it refers (I think) to the estimate of the number of nuclear missile carriers possible by 1975.

Notice the shift from the cobalt bomb to massive versions of the uranium bomb. Why?  Because as Howard Morland points out here the U-Bomb has a higher prompt dose than the C-bomb and is the easiest possible H-bomb to build –see the link below. (To design clean is harder: Sakharov took great pains to avoid the dirtier U-bomb design aspects and making the Tsar Bomba heavier for the yield to be as clean as it was, working under political pressure from Khrushchev and racing time for a certain detonation date):
 But in a secret April 1954 letter Carson Mark points out that “for the purpose of maintaining some high level of contamination over a stated period and also for the purpose of increasing the total radiation dose” no deliberate contaminating agent such as cobalt or tantalum would be as effective as the uranium fission products produced by the standard, dirty H-bomb. As he put it, “only a mild enhancement of radiation levels appear possible with present thermonuclear bombs.” In his evaluation, the standard H-bomb was the dirtiest possible bomb.

Glasstone, the official Oak Ridge historian, managed to get his own version of that statement into public print in 1957 in an unclassified book called The Effects of Nuclear Weapons, published by the Atomic Energy Commission. In a section titled “Radiological Warfare,” he discussed “the possibility of using radioactive material deliberately as an offensive weapon.” After describing the problems with various proposals such as the cobalt bomb, he writes that the problems have been solved “with the development of bombs having high fission energy yields. …they are, in effect, weapons of radiological warfare. ...Radiological warfare has thus become an automatic extension of the offensive use of nuclear weapons of high yield.”

The wording of that last phrase clearly implies that all nuclear weapons are essentially fission devices, which I believe is correct. In the 1964 edition of the book, which had very few changes, the word “fission” was added as the next to last word of the above statement: “weapons of high fission yield” rather than “weapons of high yield.” A reader could now imagine that we routinely deployed high-yield weapons that were mostly fusion-powered and that the radiological warfare discussion applied only to a small class of particularly dirty, high-fission H-bombs, rather than to all of them. In the 1977 edition, the entire three-paragraph confession was eliminated altogether. In 1978, I asked Samuel Glasstone why that section had been removed. “Lack of interest,” he said. Had the fission percentage of the U.S. nuclear stockpile been significantly reduced? “Oh no, the weapons haven’t changed, but people aren’t interested in talking about radiological warfare anymore.” Perhaps because radiological warfare is considered a war crime.

Even before the roots of the Cobalt Bomb in 1950, already in the 40s  radiological warfare was being considered. A July 1950 article in the Bulletin of the Atomic Scientists by Louis Ridenour examines the work of Hans Thirring Professor of Physics at the University of Vienna, in a paper published in 1948

Quoting the article: “Radioactive poisoning of this sort is a novel thing. It can be regarded as a horrid and insidious weapons since the person in a poisoned area has no way of knowing that he is in danger by the eveidence of his senses or by any unsophisticated test. He may receive a lethal dose of radiation two weeks before he is endangered and yet a few days later he may be dead…(but given warning) it gives each member of a target population a choice of whether he will live or die…to a person who flees at once with a folded dampened handkerchief over his nose and mouth…”
Ridenour then paraphrases Thirring presumably because the original paper is in German.

“…the monthly production of fission products is 250 curies per kilowatt for every gigawatt of reactor power contamination per month of an area of 125 square kilometers is possible….

Thirring does suggest that when they are separated a water solution of their salts should be dried onto prepared sand or metal powder, the particles of the latter being chosen of the size wanted. He estimates that one-half of 1 percent of  the weight of the finished contaminated sand …should be active fission products…this yields a specific activity of a million curies for each kilograms of “death sand” as he calls the mixture …to give a surface activity of 2 curies per square meter would weigh only 12 milligrams per square meter and would be quite invisible.

Thirring …concludes that about one tenth of a millicurie of fission products is likely to produce death if retained inside the body…while particles of 3 microns are 80 percent retained within the body smaller particles are breathed out with less retention..he estimates that…where the surface contamination amounts to 2 curies per square meter the concentration of radioactive dust a few feet from the ground is likely to be such that a fatal internal dose can be ingested by taking 500 breaths this will occupy the normal person about half an hour.

Incidentally Thirring also deduced that the hydrogen bomb was dependent on an atomic fission match to light the hydrogen fuse– in 1946!  Although this is not the Teller-Ulam geometry he also correctly anticipates the use of lithium deuteride as fusion fuel.

By all accounts a most knowledgeable physicist.  

With that article by Thirring  we have seen that the idea of radiological warfare was so to speak –in the air– at the time of the cobalt bomb broadcast.

Until this point we have gone to the edge of the Cuban Missile Crisis in 1962. At that time the Soviets could strike Britain, say with 17 times the nuclear ordinance that Britain could lay on the USSR, and the USA could strike the USSR with 17 times more than the USSR could hit  the USA with. (Those numbers are picked to contrast actually deliverable numbers from raw stockpile numbers and are only an approximation.)  

From a US military point of view, IF you WERE going to have a war with Russia that you could not escape, especially since they would catch up, this was the time.,+was+going+to+have+to+fight+a+nuclear+war+with+the+Soviet+Union,+and+he+was+absolutely+certain+of+that&source=bl&ots=qiX5w453DI&sig=mjAUI1ZE8aCGVI1Aldbf_uGRRdc&hl=en&sa=X&ved=0ahUKEwjRn6Hk6rDKAhUC1ywKHVA7AbkQ6AEIGzAA#v=onepage&q=the%20U.S.%20in%20particular%2C%20was%20going%20to%20have%20to%20fight%20a%20nuclear%20war%20with%20the%20Soviet%20Union%2C%20and%20he%20was%20absolutely%20certain%20of%20that&f=false

 But for 17 years the world had been at first stunned, then uncomfortable, and eventually nearly consumed with fear of the exterminationist mentality allied with the military atom. (Not that that was official policy but that the enemy might do it to you and you couldn’t prove they wouldn’t be willing to so lacking real-time satellite data  you would be forced to take armed precautions– an arms race, and armed nuclear bombers and missiles ready to go on high alert.)

I have often said that if a nuclear war happened it would happen like this: 

  • He  MIGHT. 
  • So I COULD.
  • So he WILL. 
  • So I MUST.  

That runaway logic could repeatedly lead to serious, serious incidents,  and enough of those and who knows what could happen?

  In the second part of this post  Freedom From Nuclear Fear II: The 1964 Consensus,  I advance the idea that the tension built up in this article was coiled like a tightly wound spring in many psyches, and the Cuban Missile crisis gave a horrible example of how a nuclear war could and probably would happen if things went on the way they were going.  The civilian anti-nuclear movement happened, in this hypothesis, after  the real military danger was over, in kind of imitation of a silent revolt led by scientists who believed the world was in serious danger and something needed to be done. Do I have proof of this? No. Just reading between the lines of many many old articles and accounts.  But it would account for the sudden change in the world’s direction after 1962. Why 1964?  Because about a year after the Cuban Missile crisis President Kennedy was assassinated and the world was again stunned.  Literally anything could happen.  And within a few months, it began to.

If you liked this article, please give it a quick review on ycombinator or StumbleUpon. Thanks

About The Author