The Nuclear Age
The future depends on people. People are unpredictable. Therefore, the
future is unpredictable. However, some general conditions of mankind
depend on things like the development of technology, the control won by
man over nature and the limitations of natural resources. These can be
predicted with a little greater confidence. The future is unknown but in
some respects its general outline can be guessed.
Such guesses are important. They influence our present outlook and our
present actions.
The nuclear age has not yet started. Our sources of energy are not yet
nuclear sources. Even in the military field, where development has been
most rapid, the structure of the armed forces has not yet adjusted
itself to the facts of the nuclear age in a realistic manner. In
politics the atomic nucleus has entered as a promise and as a menace—not
as a fact on which we can build and with which we can reckon.
Some technical predictions seem safe:
Nuclear energy will not render our older power plants obsolete in the
near future. But nuclear energy will make it possible to maintain the
pace—even the acceleration—of the industrial revolution. It will be
possible to produce all the energy we need at a moderate cost.
Furthermore—and this is the important point—this energy will be
available at any place on the globe at a cost which is fairly uniform.
The greater the need for power, the sooner will it be feasible to
satisfy the need with the help of nuclear reactors.
Nuclear energy can be made available at the most outlandish places. It
can be used on the Antarctic continent. It can be made to work on the
bottom of the ocean.
The expanding front of industrialization has been called the “revolution
of rising expectations.” That nuclear energy should be involved in the
current and in the turbulence of this expanding front, is inevitable.
One can say a little more about the effects of scientific and
technological discoveries on the relations among the people of the
globe. With added discoveries raw materials will no longer be needed
with the old urgency. For most substances substitutes are being found.
This may make for greater economic independence.
On the other hand, new possibilities will present themselves. We shall
learn how to control the air and how to cultivate the oceans. This will
call for cooperation and more interdependence.
The dangers from radioactive by-products will act in a similar
direction. The radioactive cloud released from a reactor accident may be
more dangerous than a nuclear explosion. Such a cloud will not stop at
national boundaries. Some proper form of international responsibility
will have to be developed.
What effect the existence of nuclear weapons will have upon the
coexistence of nations is a question less understood and less explored
than any other affecting our future. Most people turn away from it with
a feeling of terror. It is not easy to look at the question with calm
reason and with little emotion.
A few predictions seem disturbing but are highly probable:
Nuclear secrets will not keep. Knowledge of nuclear weapons will spread
among nations—at least as long as independent nations exist.
Prohibition will not work. Laws or agreements which start with the word
“don’t” can be broken and will always be broken. If there is hope, it
must lie in the direction of agreements which start with the word “do.”
The idea of “Atoms for Peace” succeeded because it resulted in concrete
action.
An all-out nuclear war between the major powers could occur but we may
have good hope that it will not occur if we remain prepared to strike
back. No one will want to provoke the devastation of his own country.
Atomic bombs may be used against cities. But there will be no military
advantage in destroying cities. In a short and highly mobile war neither
centers of supply and communication nor massive means of production will
count. If cities are bombed, this will be done primarily for reasons of
psychological warfare. We must be and we are prepared for this kind of
war but only as a measure of retaliation. There is good reason to
believe that as long as we are prepared for all-out war, our civilian
population will not suffer from a nuclear attack.
The certainty of a counterblow gives real protection against all-out
war. No such protection exists against wars limited in territory and in
aims. In the history of mankind such wars have been most frequent. There
is no indication that these limited wars have ended. We must be prepared
for these conflicts with effective and mobile units, and this requires
the use of nuclear firepower.
Nuclear weapons will certainly have a profound effect upon such limited
warfare. Not all of this effect need be and indeed it must not be in the
direction of greater devastation.
In a nuclear war it will not make sense to use massed manpower. Any such
concentration will provide too good a target for atomic weapons. To use
big, costly and conspicuous machines of war will be unwise. Such
machines will be defeated by nuclear explosions in the same way as the
mailed knight went down before firearms.
Any fighting unit in a nuclear war will have to be small, mobile,
inconspicuous and capable of independent action. Such units whether on
sea, land or in the air cannot rely and will not rely on fixed lines of
supply. There will be no possibility and no need to occupy territory and
to fight at fixed and definite fronts. If a war should be fought for
military reasons and for military advantage, it will consist of short
and sharp local engagements involving skill and advanced techniques and
not involving masses that slaughter and are being slaughtered.
If an invader adopts extreme dispersion, it will become impossible to
defeat him with atomic weapons. But a very highly dispersed army can be
defeated by a determined local population. Therefore the main role of
nuclear weapons might well be to disperse any striking force so that the
resistance of people defending their homes can become decisive. Nuclear
weapons may well become the answer to massed armies and may put back the
power into the hands where we believe it belongs: the hands of the
people.
At this point we are brought back to the main topic of this book:
radioactivity. In a limited nuclear war the radioactive fallout will
probably kill many of the innocent bystanders. We have seen that the
testing program gives rise to a danger which is much smaller than many
risks which we take in our stride without any worry. In a nuclear war,
even in a limited one, the situation will probably be quite different.
That noncombatants suffer in wars is not new. In a nuclear war, this
suffering may well be increased further due to the radioactive poisons
which kill friend and foe, soldier and civilian alike.
Fortunately there exists a way out. Our early nuclear explosives have
used fission. In the fission process a great array of radioactive
products are formed, some of them intensely poisonous. More recently we
have learned how to produce energy by fusion. Fusion produces fewer and
very much less dangerous radioactivities. Actually the neutrons which
are a by-product of the fusion reaction may be absorbed in almost any
material and may again produce an assortment of radioactive nuclei.
However, by placing only certain materials near the thermonuclear
explosion, one may obtain a weapon in which the radioactivity is
harmless. Thus the possibility of clean nuclear explosions lies before
us.
Clean, flexible and easily delivered weapons of all sizes would make it
possible to use these bombs as we want to use them: as tools of defense.
When stopping an aggressor we would not let loose great quantities of
radioactive atoms which would spread death where we wanted to defend
freedom. Clean nuclear weapons would be the same as conveniently
packaged high explosives. They would be nothing more.
The possibility of clean explosions opens up another development: the
use of nuclear explosives for the purposes of peace. Conventional high
explosives have been used in peace fully as much as in war. From mining
to the building of dams there is a great variety of important jobs that
dynamite has performed. Nuclear explosives have not been used in a
similar way. The reason is the danger from radioactivity. Once we fully
master the art of clean explosions peaceful applications will follow and
another step will be made in controlling the forces of nature.
All this is of course only a small part in the process of the increasing
power of man and the increasing responsibility of man. As the impossible
of yesterday becomes the accomplished fact of today we have to be more
and more aware of our neighbors on this shrinking planet. The arts of
peace may lead to conflicting interest as easily as they may lead to
fruitful cooperation. If we ever learn to control the climate of the
world, a nation may find itself in the same relation to another nation
as two farmers who have to use the waters of the same river.
Rivals are men who fight over the control of a river. When the same word
“rivals” comes to mean cooperation for the best common use of the river
or any other resource—that will be the time of law and of peace. Surely
this sounds like Utopia and no one sees the way. But the general
direction in which we should go is not to consider atomic explosives and
radioactivity as the inventions of the devil. On the contrary, we must
more fully explore all the consequences and possibilities that lie in
nature, even when these possibilities seem frightening at first. In the
end this is the way toward a better life. It may sound unusually
optimistic in the atomic age, but we believe that the human race is
tough and in the long run the human race is reasonable.
GLOSSARY
Activity: Short for radioactivity. Also the strength of a radioactive
source measured in disintegrations per second.
Air burst: A nuclear explosion at such an altitude that the fireball
does not touch the earth’s surface. An air burst produces very
little local fallout.
Alpha ray (particle): Energetic but non-penetrating radiation emitted by
heavy radioactive nuclei. An alpha particle consists of two
neutrons and two protons, and is identical with the nucleus of the
ordinary helium atom.
Atom: A positively charged nucleus surrounded by negatively charged
electrons.
Atomic bomb: A fission bomb.
Atomic cloud: The cloud remaining after the energy of the explosion has
been carried off by the shock wave and the thermal radiation. It
consists of condensed water vapor, ground material, and bomb
debris including the radioactivity.
Atomic energy: Energy released in nuclear reactions, for example in
fission. Atomic energy and nuclear energy mean the same thing, but
the latter name is more appropriate.
Atomic reactor: Same as nuclear reactor.
Background radiation: Natural radiation due to cosmic rays, and due to
radioactive substances in the earth, in the atmosphere, and in our
own bodies.
Beta ray (particle): An energetic electron or positron emitted by some
radioactive nuclei. Practically all of the fission products are
beta (electron) emitters.
Blast wave: Same as shock wave.
Cesium¹³⁷: A radioactive fission product. It emits a 0.5 million volt
beta ray and a 0.7 million volt gamma ray with a half-life of 30
years. The daughter nucleus is stable barium¹³⁷.
Chain reaction: Self-maintained sequence of fissions. Neutrons released
by the fission of one nucleus are used to induce fission in
another nucleus.
Chromosome: A small irregularly shaped body found in cells. Chromosomes
carry the genes, which are responsible for heredity.
Clean bomb: A nuclear bomb which produces heat and blast, but only a
negligible amount of radioactivity. The energy of such a bomb is
derived almost entirely from the fusion process.
Cobalt⁶⁰: Radioisotope—decays into nickel⁶⁰ with the emission of a weak
beta ray. The half-life for this decay is 5.3 years. The nickel⁶⁰
immediately ejects two gamma rays with a total energy of 2.5
million electron-volts.
Cobalt bomb: A radiological bomb which produces a large quantity of
cobalt⁶⁰.
Control rod: A rod of neutron-absorbing material used to control the
power level of a nuclear reactor.
Cosmic rays: Energetic particles from outer space. They induce nuclear
reactions in the earth’s atmosphere and thus contribute to the
background radiation. This cosmic radiation is more intense at
high altitudes than at sea level.
Counter: A device which detects nuclear radiation.
Critical mass: The amount of fissionable material required to sustain a
steady chain reaction. With less than the critical amount, the
reaction stops because too many neutrons are lost.
Cyclotron: A machine that accelerates charged particles to high energy.
Energetic charged particles can be used to induce nuclear
reactions.
Daughter: The nucleus which remains after decay of a radioisotope.
Decay: Spontaneous process in which a radioactive nucleus emits an
alpha, beta, or gamma ray.
Delayed neutrons: Those released after a fraction of a second to a
half-minute or so by the fission products. They comprise less than
one per cent of the total number of neutrons released in the
fission process but are useful for the purpose of control in
reactors.
Deuterium: Stable hydrogen isotope. Its nucleus (called a deuteron)
consists of one proton and one neutron.
Disintegration: Same as decay.
Dose: A quantity of radiation—usually measured in roentgens.
E = mc²: Einstein’s equation relating mass (m) and energy (E). The speed
of light (c) enters as a proportionality constant. The equation
asserts that one pound of mass is equivalent to ten megatons of
energy. In the fission process only one-tenth of one per cent of
the mass is converted. Therefore, to produce ten megatons of
energy by fission 1000 pounds of uranium would be required.
Electromagnetic radiation: Includes radio waves, visible, infrared, and
ultraviolet waves; also X-rays and gamma rays. The latter two are
energetic, penetrating forms of radiation.
Electron: A particle having a unit negative charge and a weight equal to
1/1840 of the weight of the lightest atom (hydrogen).
Electron capture: process in which an atomic electron unites with a
proton in the nucleus producing a neutron and a neutrino.
Electron-volt: The amount of energy acquired by an electron which is
accelerated through an electric potential of one volt. Typically,
the energy required to “knock” an electron out of an atom is a few
electron-volts or so; particles ejected from radioactive nuclei
have energies between a few hundred thousand and a few million
electron-volts.
Element: A collection of atoms whose nuclei all have the same charge. An
element may consist of many isotopes.
Enriched material: Uranium which contains a greater proportion of the
235-isotope than is found in the natural ore.
Excited state: A state of an atom, molecule, or nucleus having excess
energy. As soon as possible this excess energy is released and the
system goes to the ground state.
Fallout: Radioactive particles from an atomic explosion. They may be
carried in the atomic cloud to large distances from ground zero
and then “rained down” to the earth’s surface.
Fireball: The luminous ball of hot air and bomb material which expands
and cools as the shock wave races out.
Fission: The breaking-up of a heavy nucleus into two or more fragments.
A large amount of energy and some free neutrons are released in
the process.
Fissionable material: Isotopes which undergo fission when bombarded by
_slow_ neutrons: uranium²³⁵ and plutonium²³⁹.
Fission products: Fission fragments and their daughters, including
hundreds of different radioactive species, among them strontium⁹⁰
and cesium¹³⁷.
Fusion: The combining of light nuclei into heavier ones with a release
of energy. For example, deuteron + triton → alpha + neutron. About
18 million electron-volts are released in this process.
Gamma ray: Energetic, penetrating electro-magnetic radiation emitted by
certain radioactive nuclei, frequently after a beta emission.
Genes: Parts of the chromosomes. They are big molecules that determine
heredity.
Ground state: The state of least energy and greatest stability of atoms,
molecules, and nuclei.
Ground zero: The point on the surface of the earth directly above or
below a nuclear explosion.
Half-life: The time required for one half of a large number of identical
radioactive nuclei to disintegrate.
H-bomb: Same as hydrogen bomb.
Heavy hydrogen: Same as deuterium.
Heavy water: Water with heavy hydrogen substituted for ordinary
hydrogen.
Hydrogen bomb: A high-yield thermonuclear bomb.
Iodine¹³¹: A radioactive fission product with a half-life of 8 days. It
emits an electron of average energy 0.2 million electron-volts and
a gamma ray of energy 0.4 million electron-volts.
Ion: A charged atom or molecule. Ions are produced in abundance when
energetic charged particles pass through matter.
Ionization: The process of removing electrons from neutral atoms or
molecules. Neutrons and gamma rays as well as energetic charged
particles are very effective in producing ionization.
Iridium¹⁹²: 75 day radioisotope. It emits an electron of average energy
0.2 million volts and a 0.3 million volt gamma ray.
Isotopes: Atoms whose nuclei have the same number of protons but a
different number of neutrons. Such atoms have the same chemical
behavior.
Kiloton: The amount of energy released by a thousand tons of TNT.
Krypton⁸⁵: A radioactive fission product. It has a ten year half-life
and emits an electron of average energy 0.2 million volts and a
0.5 million volt gamma ray.
Leukemia: A usually fatal disease in which white blood cells are
overproduced.
Local fallout: Radioactive fallout in the neighborhood of a nuclear
explosion.
Megaton: The amount of energy released by a million tons of TNT.
Meson: A particle intermediate in weight between the electron and the
proton. Actually, there are two kinds of mesons, called pi and mu.
The pi meson weighs 276 times as much as the electron and is
connected with the forces that hold the nucleus together. The mu
meson weighs 212 times as much as the electron and contributes
appreciably to the cosmic radiation.
Microsecond: One millionth of a second. It takes light 5 microseconds to
go a mile.
Million volt particle: Short for million electron-volt particle.
Moderator: A material used in nuclear reactors to reduce the speed of
neutrons.
Molecule: A combination of atoms held together chemically.
Mutation: A genetic change, which is transmitted to offspring and
affects hereditary characteristics. Such changes in genes may be
caused by radiation as well as chemical and thermal agents.
Neutrino: A weightless, uncharged particle which carries off energy in
the process of beta decay.
Neutron: A neutral particle, one of the basic constituents of the
nucleus. A neutron weighs slightly more than a proton, and when
free, decays into a proton plus an electron and a neutrino.
Noble gases: Helium, neon, argon, krypton, and xenon. They do not
combine chemically with any elements including themselves.
Nuclear bomb: A bomb which derives its energy from nuclear fission or
fusion.
Nuclear reactor: A machine for maintaining a controlled chain reaction.
Nucleus: The core of an atom, consisting of neutrons and protons. Its
charge is equal to the number of protons. Its weight is equal to
the number of protons plus the number of neutrons.
Periodic system: The chemical elements arranged in order of increasing
atomic charge. Elements with similar chemical properties occur
periodically.
Plutonium: Element with charge 94, produced by capturing a neutron in
uranium²³⁸ followed by two beta emissions. Like uranium²³⁵,
plutonium is valuable as an atomic fuel.
Positron: The positive counterpart of the electron.
Potassium⁴⁰: A natural radioactive isotope. It has a half-life of one
billion years and emits beta and gamma rays.
Proton: A constituent of the nucleus. It has one unit of positive charge
and weighs slightly less than a neutron.
Radiation: Energetic charged particles, neutrons and gamma rays which
cause ionization in matter. Radiation is produced in nuclear
explosions but also occurs naturally from cosmic rays and from the
decay of radioactive substances in our surroundings.
Radioactivity: Spontaneous nuclear decay, releasing an alpha, beta, or
gamma ray.
Radioisotope: Short for radioactive isotope.
Radiological bomb: A bomb designed to create radioactive contamination.
Radium: Element with charge 88. The principal isotope has a weight of
226 and emits an alpha particle with a half-life of 1620 years.
Range: Distance traveled by an energetic charged particle in matter
before it stops. Heavy charged particles move in a straight line
inside matter, but electrons frequently change their course. For
this reason the range of electrons is only about one-half the
total distance traveled.
Reactor: Same as nuclear reactor.
Roentgen: A measure of radiation dose—defined in terms of the amount of
energy deposited per unit weight of irradiated material. A dose of
400,000 roentgens in living tissue deposits enough energy to raise
the temperature by 1°C. A dose of only 400 roentgens in a human
being will cause death fifty per cent of the time.
Shock wave: Expanding front of high pressure and strong winds produced
by an explosion.
Spontaneous fission: Natural fission, not induced by a neutron. The
half-life for this process in uranium²³⁸ is 8 × 10¹⁵ years.
Stratosphere: The atmosphere above the weather zone. The altitude of the
stratosphere varies from thirty to fifty thousand feet depending
on latitude and season.
Stratospheric fallout: World-wide fallout from big bombs whose clouds
rise into the stratosphere. On the average the radioactivity
remains in the stratosphere for about ten years and is then
deposited more or less uniformly over the surface of the earth.
Strontium⁹⁰: A radioactive fission product. It has a half-life of 28
years and emits two electrons of average total energy 1.2 million
electron-volts. Strontium is chemically similar to calcium and
gets deposited in bones.
Thermal radiation: Electromagnetic radiation, mainly visible, but also
ultraviolet and infrared, emitted from the fireball of a nuclear
explosion and transmitted long distances in the surrounding cold
air.
Thermonuclear bomb: A bomb which derives a significant fraction of its
energy from the fusion of hydrogen isotopes.
Thermonuclear reaction: A fusion reaction induced by high temperature.
Thorium: Element with charge 90. The principal isotope has a weight of
232 and emits an alpha particle with a half-life of 14 billion
years.
Trigger process: A small cause which leads to a big effect.
Tritium: An isotope of hydrogen. Its nucleus (called a triton) consists
of one proton and two neutrons. Tritons are radioactive beta
emitters having a half-life of 12.25 years.
Troposphere: The weather portion of the atmosphere, from sea level to
about forty thousand feet.
Tropospheric fallout: World-wide fallout, mainly from small bombs (less
than a megaton) whose clouds remain in the troposphere. This
fallout occurs on the average two weeks to a month after the
explosion and stays in a latitude close to the latitude of the
explosion.
Uranium: Element with charge 92. Natural uranium contains 1 part of U²³⁵
to 139 parts of U²³⁸. U²³⁵ is a fissionable material and U²³⁸ can
be converted to plutonium, which is fissionable.
X-ray: Penetrating electromagnetic radiation, usually made by bombarding
a metal target with energetic electrons. X-rays and gamma rays are
really the same thing.
FOOTNOTES
[1]The word “noble” is perhaps a misnomer—these atoms do not even seek
the company of each other.
[2]Quotes are put around the word atom because, having lost one of its
electrons, it is no longer an ordinary neutral atom in its ground
state.
[3]Yet.
[4]Actually the same state may be occupied by two neutrons and two
protons. The reason is that neutrons and protons are magnetic
particles with a north and a south pole. Consequently the demand for
a difference can be satisfied by having one neutron (or proton) with
its north pole pointing up and another with its north pole pointing
down.
[5]It seems that neutrinos emitted in the company of electrons have the
symmetry of a right screw; those emitted together with a positron
have the symmetry of a left screw.
[6]Actually the weights rarely add up to the original 238 because, as a
rule, one or more neutrons are emitted which carry off some of the
original mass.
[7]Only a very few unlucky ones are overtaken by beta decay first.
[8]She and her husband were the discoverers of two elements, rhenium and
masurium. One of these exists.
[9]A great portion of the energy might be lost if the neutron is quite
fast. In this case the neutron can cause internal excitation of the
nucleus.
[10]There seems to be a good possibility that he died from a hepatitis
entirely unrelated to the initial radiation exposure.
[11]Half-lives of radioactive nuclei are uninfluenced by the extreme
temperatures or pressures of the explosion, or by the state of
motion of the particles or where they happen to be.
[12]A small amount may drift down to the ground in the winds. This may
get deposited on leaves and grass.
[13]The last line of the table is based on our own estimates.
[14]Recent evidence suggests this number is sometimes twenty-three.
[15]Dubbed by its friends “Committee for Reactor Prevention.”
[16]One of the authors.
[17]This difference is not surprising. When we sterilize, we have to
kill _all_ germs, even those which are most resistant to radiation.
Furthermore small organisms may escape the radiation effects by mere
chance. On the other hand a big and complicated organism will cease
to function when the most sensitive among its essential tissues have
been destroyed.
Transcriber’s Notes
—Silently corrected a few typos.
—Retained publication information from the printed edition: this eBook
is public-domain in the country of publication.
—In the text versions only, text in italics is delimited by
_underscores_.