Heinlein, Robert A – Expanded Universe

Harper was unconvinced. “I don’t know,” be mused. ‘I don’t think it’s faith;

I think it’s lack of imagination and knowledge.”

Notwithstanding King’s confidence, Lentz did not show up until the next day.

The superintendent was subconsciously a little surprised at his visitor’s

appearance. He had pictured a master psychologist as wearing flowing hair, an

imperial, and having piercing black eyes. But this man was not overly tall, was

heavy in his framework, and fat-almost gross. He might have been a butcher. Little,

piggy, faded-blue eyes peered merrily out from beneath shaggy blond brows. There was

no hair anywhere else on the enormous skull, and the ape-like jaw was smooth and

pink. He was dressed in mussed pajamas of unbleached linen. A long cigarette holder

jutted permanently from one corner of a wide mouth, widened still more by a smile

which suggested unmalicious amusement at the worst that life, or men, could do. He

had gusto. King found him remarkably easy to talk to.

At Lentz’ suggestion the Superintendent went first into the history of

atomic power plants, how the fission of the uranium atom by Dr. Otto Hahn in

December, 1938, had opened up the way to atomic power. The door was opened just a

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crack; the process to be self perpetuating and commercially usable required an

enormously greater knowledge than there was available in the entire civilized world

at that time.

In 1938 the amount of separated uranium-235 in the world was not the mass of

the head of a pin. Plutonium was unheard of. Atomic power was abstruse theory and a

single, esoteric laboratory experiment. World War II, the Manhattan Project, and

Hiroshima changed that; by late 1945 prophets were rushing into print with

predictions of atomic power, cheap, almost free atomic power, for everyone in a year

or two.

It did not work out that way. The Manhattan Project had been run with the

single-minded purpose of making weapons; the engineering of atomic power was still

in the future.

The far future, so it seemed. The uranium piles used to make the atom bomb

were literally no good for commercial power; they were designed to throw away power

as a useless byproduct, nor could the design of a pile, once in operation, be

changed. A design-on paper-for an economic, commercial power pile could be made, but

it had two serious hitches. The first was that such a pile would give off energy

with such fury, if operated at a commercially satisfactory level, that there was no

known way of accepting that energy and putting it to work.

This problem was solved first. A modification of the Douglas-Martin power

screens, originally designed to turn the radiant energy of the sun (a natural atomic

power pile itself) directly into electrical power, was used to receive the radiant

fury of uranium fission and carry it away as electrical current.

The second hitch seemed to be no hitch at all. An “enriched” pile-one in

which U-235 or plutonium had been added to natural uranium-was a quite satisfactory

source of commercial power. We knew how to get U-235 and plutonium; that was the

primary accomplishment of the Manhattan Project.

Or did we know how? Hanford produced plutonium; Oak Ridge extracted U-235,

true-but the Hanford piles used more U-235 than they produced plutonium and Oak

Ridge produced nothing but merely separated out the 7/10 of one percent of U-235 in

natural uranium and “threw away” the 99%-plus of the energy which was still locked

in the discarded U-238. Commercially ridiculous, economically fantastic!

But there was another way to breed plutonium, by means of a high-energy,

unmoderated pile of natural uranium somewhat enriched. At a million electron volts

or more U-238 will fission at somewhat lower energies it turns to plutonium. Such a

pile supplies its own “fire” and produces more “fuel” than it uses; it could breed

fuel for many other power piles of the usual moderated sort.

But an unmoderated power pile is almost by definition an atom bomb.

The very name “pile” comes from the pile of graphite bricks and uranium

slugs set up in a squash court at the University of Chicago at the very beginning of

the Manhattan Project. Such a pile, moderated by graphite or heavy water, cannot