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 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 explode.

Nobody knew what an unmoderated, high - energy pile might do. It would breed plutonium in great quantities - but would it explode? Explode with such violence as to make the Nagasaki bomb seem like a popgun?

Nobody knew.

In the meantime the power - hungry technology of the United States grew still more demanding. The Douglas Martin sunpower screens met the immediate crisis when oil became too scarce to be wasted as fuel, but sunpower was limited to about one horsepower per square yard and was at the mercy of the weather.

Atomic power was needed - demanded.

Atomic engineers lived through the period in an agony of indecision. Perhaps a breeder pile could be controlled. Or perhaps if it did go out of control it would simply blow itself apart and thus extinguish its own fires. Perhaps it would explode like several atom bombs but with low efficiency. But it might - it just might - explode its whole mass of many tons of uranium at once and destroy the human race in the process.

There is an old story, not true, which tells of a scientist who had made a machine which would instantly destroy the world, so he believed, if he closed one switch. He wanted to know whether or not lie was right. So he closed the switch - and never found out.

The atomic engineers were afraid to close the switch.

"It was Destry's mechanics of infinitesimals that showed a way out of the, dilemma," King went on. "His equations appeared to predict that such an atomic explosion, once started, would disrupt the molar mass enclosing it so rapidly that neutron loss through the outer surface of the fragments would dampen the progression of the atomic explosion to zero before complete explosion could be reached. In an atom bomb such damping actually occurs.

"For the mass we use in the pile, his equations predicted possible force of explosion one - seventh of one percent of the force of complete explosion. That alone, of course, would be incomprehensibly destructive - enough to wreck this end of the state. Personally, I've never been sure that is all that would happen."

"Then why did you accept this job?" inquired Lentz.

King fiddled with items on his desk before replying. "I couldn't turn it down, doctor I couldn't. If I had refused, they would have gotten someone else - and it was an opportunity that comes to a physicist once in history."

Lentz nodded. "And probably they would - have gotten someone not as competent. I understand, Dr. King - you were compelled by the 'truth - tropism' of the scientist. He must go where the data is to be found, even if it kills him. But about this fellow Destry, I've never liked his mathematics; he postulates too much."

King looked up in quick surprise, then recalled that this was the man who had refined and given rigor to the calculus of statement. "That's just the hitch," he agreed. "His work is brilliant, but I've never been sure that his predictions were worth the paper they were written on. Nor, apparently," he added bitterly, "do my junior engineers."

He told the psychiatrist Of the difficulties they had had with personnel, of how the most carefully selected men would, sooner or later, crack under the strain. "At first I thought it might be some degenerating effect from the neutron radiation that leaks out through the shielding, so we improved the screening and the personal armor. But it didn't help. One young fellow who had joined us after the new screening was installed became violent at dinner one night, and insisted that a pork chop was about to explode. I hate to think of what might have happened if he had been on duty at the pile when he blew up."

The inauguration of the system of constant psychological observation had greatly reduced the probability of acute danger resulting from a watch engineer cracking up, but King was forced to admit that the system was not a success; there had actually been a marked increase in psychoneuroses, dating from that time.

"And that's the picture, Dr. Lentz. It gets worse all the time. It's getting me now. The strain is telling on me; I can't sleep, and I don't think my judgment is as good as it used to be - I have trouble making up my mind, of coming to a decision. Do you think you can do anything for us?"

But Lentz had no immediate relief for his anxiety. "Not so fast, superintendent," he countered. "You have given me the background, but I have no real data as yet. I must look around for a while, smell out the situation for myself, talk to your engineers, perhaps have a few drinks with them, and get acquainted. That is possible, is it not? Then in a few days, maybe, we know where we stand."