Stanislaw Ulam came up with the climactic idea that made it possible to
achieve the goal of the superbomb
program: they invented a configuration
that would make it possible for a small
fission explosion to ignite an arbitrarily
large fusion explosion.
The first test of a device designed to
ignite a large thermonuclear explosion
sors had been, andit is at least possible
and most famous of these tests, with
the code name Bravo, was exploded
have been involved let us next examine
the superbomb in Operation Castle.
Their yields varied widely. The first
by meansof a comparatively small quan-
on March 1, 1954, at Bikini. Its design,
Eniwetok on November 1, 1952 {local
explosion, also incorporated the Teller-
tity of fissionable material took place at
time). The device, known as Mike, produced a tremendous explosion, equiva-
lent in its energy release to 10 megatons
(10 million tons) of TNT. As had been
repeatedly predicted since the early
1940’s, the yield was roughly 1,000
times larger than the yield of the first
atomic bombs. For certain practical reasons relating to the pioneering nature of
which was initiated before the Mike
Ulam configuration, but it had the more
practical lithium deuteride as its thermonuclear fuel. Bravo's yield was 15
megatons, even more than Mike’s, and
it was readily adaptable to-delivery by
aircraft.
On November 23, 1955, the U.S.S.R.
exploded a bomb that had a yield of a
few megatons. According to a statement
the test, this first version of the Teller- made by Secretary Khrushchev, this
Ulam configuration had liquid deute- device imvolved an “important new
rium as its thermonuclear fuel. (The achievement” that madeit possible by
last point needs special emphasis. The
Teller-Ulam invention, contrary to folklore, was not the notion of substituting
easy-to-handle lithium deuteride for the
hard-to-handle liquid deuterium. That
possibility had been recognized several
yearsearlier.)
Also in November, 1952, the U.S.
“using a relatively small quantity of fissionable material...to produce an explosion of several megatons.” Khrushchev’s remark is generally taken as
confirmation that the test was the first
one in which the Russians incorporated
the Teller-Ulam configuration or something like it. It also used lithium deu-
tested a very powerful fission bomb, teride as a fuel and was therefore a true
with the code name King, that had an superbomb, comparable to the U.S.
explosive yield of 500 kilotons, or half . Bravo device exploded 20 months eara megaton. Its purpose was to provide lier, except for its yield, which was still
the U.S. with an extraordinarily power- probably only about a fifth the yield
fal bomb by means of a straightforward of Bravo.
extension of fission-weapons technology,
in case such large bombs should become Wie this chronology in mind, what
can one say about what might
necessary for any strategic or political
reason. Originally proposed by Bethe as have happened ifthe U.S. had followed
a substitute for the Super program,it the advice of Oppenheimer andtherest
became instead a backupforit.
of the General Advisory Committee,
The first Russian explosion involving backed by Lilienthal and the majority of
fusion reactions took place on August the AEC commissioners, and had not
12, 1953. Russian descriptions of this initiated a program for the specific purtest and later ones confirm that it was pose of developing the Super in the
not a superbomb. It was only some tens spring of 1950?
of times as big as the standard atomic
At best the invention of very large,
comparatively inexpensive bombsof the
bombs of the day, about the samesize
as but probably smaller than King, the
Super type would have been forestalled
largest U.S. fission bomb. It evidently or substantially delayed. Very probably
involved oneof several possible straight-
forward configurations for igniting a
fairly small amount of thermonuclear
material with a comparatively large
amount of fissionable material. It was
the first device anywhere to use lithium
deuteride as a fuel, and presumably it
could have been readily converted into
a practical weapon if there had been
ration agreements than their predeces-
been a development step the U.S. bypassed in its successful search for a configuration that would make it possible
to produce anarbitrarily large explosion
with a relatively small quantity of fissionable material.
In the spring of 1954 the U.S. successfully exploded six more variants of
the work on the booster principle, which
presumably would still have gone for-
that they might have been able to deal
successfully with the superbomb. To be
sure, such a favorable result was not
very probable (certainly it had much less
than an even chance of coming about),
butits achievement would have been so
beneficial to mankind thatat least some
small risk was clearly worth running.
To evaluate just how muchrisk would
three other outcomes, which I have la-
beled the “actual world,” the “most probable alternative world” and the “worst
plausible alternative world” [see illus-
tration on opposite page].
In both of the hypothetical alterna-
tive worlds I assumethat the U.S. would
have forgone the development of the
Super but that the Russians would have
ignored this American restraint and
would have proceeded at first just as
they did in the actual world. I also assume that the U.S. would have vigorously followed the positive elements of
the Oppenheimer committee’s advice;
thus the booster project and other ideas
for improvingfission bombs would, have
been accelerated. The difference be-
tween the most probable alternative
world and the worst plausible alternative world lies in the timing of the test
of the first Russian superbomb. In the
worst plausible world I assume that this
test would have come on the same date
that it did in the actual world. In the
most probable alternative world, however, I assume that the test would have
been substantially delayed.
In both of the two hypothetical alternative worlds, then, the Russians in Au-
gust, 1953, would have exploded Joe 4,
a large bomb deriving part of its explosive energy from a thermonuclear fuel
and yielding a few hundred kilotons.
Such a device, however, would have
had no real effect on the “balance of
terror.” In both alternative worlds the
U.S. would surely have already tested
the 500-kiloton all-fission bomb in November, 1952 (or probably earlier, since
the timing of Operation Ivy was determined by the availability of the much
more complicated Mike device). There-
fore the explosion of Joe 4 would have
meant that the U.S.S.R. had caught up
with but not surpassed the U.S. insofar
ward, would have led eventually to the
as the capability of producing enormous
damage in a single explosion was con-
bombs, but those ideas might well have
been delayed until both President Eisenhower and Secretary Khrushchev were
in power. Those two leaders were both
more seriously interested in arms-limi-
[The what would have happened?
From that point the Russians might
conceivably still have gone on to produce their multimegaton explosion in
ideas underlying the design of very big
cerned.
tatford Warren
performance of this device, Teller and
any point in doing so. It seems to have
nS NAFIUCLA
The George shot served its purpe.-
well. During the final stages of calculations concerned with the expected