Here Are the Basic Facts about the H-Bomb

T O understand the dangers in the testing and use of nuclear weapons one must know how they are made and work, Nearly all the heat and blast of both atomic and hydrogen fission) of heavy atoms of uranium and platonium into smaller pieces, _ All the pieces together weigh very slightly less than the original uranium or plutonium—an amount which for most purposes is too small to matter, but which does mean an enormous amount of heat is set free, as was explained by Einstein’s Theory of Relativity.

When a great deal of heat is set free in a very short time a violent explosion is caused, and an atomic bomb lets loose a great deal more heat than INT. One pound of uranium lets out as much heat as 2,000 tons of TNT.

The fragments left over (fission products) represent all . the ‘chemical elements of the earth, though there are more of some kinds than of others. , Small, fast, dangerous particles Unfortunately these fragments. are not exactly like the ordinary elements of which everything is made, for they continue to send out small, fast, dangerous particles for ever.

_ As time. goes on, they send out particles in smaller. and smaller numbers, but it is many years before one can stop . worrying about them.

These particles are of two important kinds—there are other ; : kinds, only one of which will have to be mentioned later, The dangerous particles or radiations are gamma-rays (a very penetrating X-ray) and beta rays (a fast moving electron).

. Beta rays can all be stopped by putting a heavy shield in their way; most of them can go less than a foot in air. Gamma rays. are only partly stopped by any shield however thick and heavy. Nevertheless the thicker and heavier the shield the — fewer gamma rays get through.

Near atomic piles, and in the atomic bomb just at the instant of explosion, there Are particles called neutrons. They are only partly. stopped by thick shields. Neutrons are not found in fall-out.

Set each other off The atomic bomb, as used against the Japanese, works by the uranium atoms setting each other off. Heat. has nothing to do with it. Every time a uranium. atom is split, two or three neutrons fly out, and if they hit another uranium atom this is likely to split too.

Only one kind of uranium, uranium-235, and only one kind of. plutonium, plutonium-239, have the power to do this. Even then a lump of about 11Ib..is needed, or too many of the neutrons fly out through the surface and do not cause another atom to split up. ’ So the bomb is fired by shooting together two lumps of uranium to make one lump weighing more than ill.

A strong, heavy case called a tamper holds the lumps together for as long as possible in order to get the biggest bang.

The ‘small’ or ‘tactical’ atomic bomb simply has a poor tamper, so as ‘to give a lesser bang. :

We see.that once one uranium atom has been split by the . source of neutrons which is built into the bomb, it sends out more neutrons to split other atoms, and so on. A lot of _ heat is set free, but does not help to split the uranium. By J. H. BRADLEY bombs come from the splitting (called Now for the H-bomb. Here heat is set free not only by ‘splitting up uranium, but also by joining together light atoms called lithium-6 and hydrogen-2 (deuterium), The products of the joining-together, or fusion, weigh less than the atoms we started with, so again a lot of heat ~ is set free. Many neutrons fly out during the fission.

The joining-together. starts when the lithium-6 and deuterlum are made very hot, about the temperature of the middle of the sun. And the hotter they get the faster they join together. The sun does not explode because it has very little lithium or deuterium.

The H-bomb is. made hot by putting it inside an atomic bomb, to get things going. 7 OO Tf this were all nobody would -be very worried, because . the atoms formed by fusion are not dangerous to health and there are not very many fission atoms from the uranium This is the first of two special articles by our scientific correspondent on the scientific and military aspects of the hydrogen bomb. They will be followed by articles from our medical correspondent on the health hazards of nuclear tests, and from Cliff Slaughter, sociologist and member of. The Newsletters editorial board,‘ on ‘How to Beat the Bomb’. ~ -This series has been designed to give workers the facts as simply and as clearly as possible; our correspondents will be glad to answer readers’ questions or deal with any difficulties. :

detonator. It would be not much worse than an ordinary atomic bomb in the radio-active products it spreads all over the earth.

But things are not done so. Lithium-6 and deuterium cost : . hundreds of pounds an ounce, while there is a lot .of unsalable uranium, called uranium-238 and no use for atomic bombs.

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And. though uranium-238 on its own will not explode, it will spit just like uranium-235 when hit by fast neutrons from a hydrogen bomb.

So a big, heavy coat of uranium-238 is put round the H-bomb, and then it turns out that one needs much less lithium-6 and deuterium than before for the same size bang. There are a lot more fission products too, which are the cause of all the fuss.

Don’t get it wrong—uranium-238 is cheap at a few pence a pound, but H-bombs still cost about £1 million each.

Now we come to what the fall-out trouble is all- about.

Fall-out is a dust of the remains of a nuclear bomb, including the dangerous radioactive fission products, Some of it falls near the test site, some it is swept up tens of thousands of feet into the air and takes years to come down.

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A hydrogen-bomb takes about five years to deposit half its dust, also all over the world, but in the USA more than anywhere else.

Now Macmillan and Eisenhower have been exploiting a -profound historical error in their claims to have a ‘clean’ H-bomb, that is, one with no fall-out in this way.

That fine white dust After the March 1954 test in which the Japanese fishermen were injured there was a great. uproar over the LOCAL. fallout, that fine white dust which hurt the Japanese, the Marshall Islanders and the U.S. servicemen.

That -dust was very largely powdered coral, sucked. up in _ the wind of the mushroom.cloud,.covered in fission products, and dropped over thousands of square miles around. The great concern was primarily that such a thing would also happen in war.

Actually that only happens if a good deal of dust is sucked up, or if there is a local rainstorm within a few hours after the explosion. It is very easily avoided by exploding the bomb above 20,000 feet over Jand, or even lower. over the sea.

Not nearly enough attention was paid in 1955 to the far more insidious and long-term effects of fall-out all over the world. And in time of- peace it is the worldwide fall-out which matters.

All Macmillan and Eisenhower mean by ‘no fall-out’ is ‘no LOCAL fall-out’—none near the test centre immediately afterwards. Plenty fell on Japan, America, and of course Europe, from Christmas Island. Very little fell into the Pacific Ocean, though that would have been the safest place for it. :

The ‘clean’ tests of Macmillan are.a greater danger than the ‘dirty’ tests of anybody else.

The Soviet Union is a little more truthful, It simply says jis tests were made ‘at a great height’. That is all the British and Americans have done for their ‘96 per cent. reduction in fall-out’.

Too.expensive to test Now there IS a clean H-bomb. It is simply made by leaving off the outer layer of uranium- -238.

It is so expensive that no nation could afford more than 10 at the very outside. Nobody will use one in any war. No-body has tested one in peace for two and a half years.

Khrushchev announced in Bangalore in 1955 that he had a bomb with ‘relatively small quantities of fissionable material’. Eisenhower has never claimed that.

The USSR does not pretend that its recent bombs have been anything. but dirty. Nobody can deceive the Japanese or anybody else about what is used in his bombs.

The USSR also. has various other types of bomb, slightly different from those I have-described, but all very. dirty. (See for instance The Newsletter, vol. 1, no. 1, May 10, 1957, or the Manchester Guardian of April 23, 1957).

The ‘differences don’t matter. They are alt as ditty as each other.

Figment of his imagination For this reason the ‘undetectable tests’ are another figment of Macmillan’s lurid imagination, Filters for collecting fallout, sensitive pressure recorders for measuring air waves, and delicate seismographs for detecting ground shocks are hidden in every Western embassy and ‘consulate in and around the USSR. ‘ High-flying aeroplanes collect samples every few hours: especially when the British or Americans suspect each other of having had a test.

What is undetectable—and makes the shifting Western positions on disarmament, control and inspection took so ridiculous—is a stockpile of atomic or hydrogen bombs. There is no such thing as a realistic inspection system for nuclear arms.

Perhaps one might be able to. work out how much uranium, plutonium and thorium each country has made within 10 per cent., by a detailed inspection of factories, records and witnesses. , ‘Within 10 per cent.’—within enough to leave bombs to blow half the world to smithereens. It leaves plenty of room for provocations and incidents over fictitious charges or real suspicious of concealing bombs.

Aerial inspection is impossible Aerial inspection for bombs—or ground inspection either —is impossible. Nuciear bombs are piled in some innocent jJooking shed in some railway yard or dock, in some barn, or in. little holes in the ground not the size of a military pillbox.

What a consolation it will be if the U.S. can carry pictures of Soviet bombers and missiles taking off against America— the day after Washington has. been flattened and New York is a heap of smoking, radio-active rubble.

But aerial inspection does give a perfect oppertunity for an aggressor to pin-point targets, and so is far too dangerous to be put into force until after substantial disarmament, gr at least till after the setting up of an effective system of radar stations.

Ground inspection can also be used for all kinds of spying:

we have to get used to this fact, because ground inspection has to come at some stage.

Aerial inspection is useful only in discovering military airfields as a preliminary to ground inspection. Even Russia’s plan for inspection at ports, junctions, military depots and airfields is not -infallible, though a good deal better than nothing.

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Holes in the ground Once ballistic missiles are hidden in little holes in the .

‘ground, once those missiles no longer need the lengthy and elaborate preparation of the U.S. versions, all talk of inspection by air or ground becomes meaningless.

We may already be too late; in two years we shall certainly be too late.

Only two kinds of inspection remain: neither gives an absolute safeguard, and.neither can touch the stockpile. Production of new missiles and new bombs can Phe prevented or enormously hindered by inspection, and not least because in a world disarmed no Government planning war can ever trust its own citizens enough.

Where there can be a Kennan, a Marshall, a Stassen, an ~ Oppenheimer or a Kapitsa, there could be more. Few politicians would care to face the. price of being caught getting ready for nuclear war.

Long-range radars all over the world can give warning of an attack ONCE IT HAS STARTED. This seems a permissible last line of defence, for all nations might have small numbers of anti-aircraft and anti-missiles under strict supervision and with merely atomic rather than H-warheads, Can be made unsuitable Such counter-missiles can be made unsuitable for anything but ground-to-air use. Supervision prevents the transfer of war heads to any other purpose. The deterrent is gone, but we are left a vestige of defence which is actually a good deal safer than all the defences we have at the present time.

It cannot be turned to aggression because of a supervision almost impossible to evade, because the failure of an inspector te report every five minutes. would call out instantly all the powers of emergency investigation.

A. conspiracy to capture within five minutes a hundred radar stations in a dozen countries is not a practical possibility.

This is not a 2 good alternative to full disarmament, but it is_a compromise which might be agreed for some years till everybody felt really safe.

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