But a self-perpetuating sequence of nuclear splitting, just wider the level of complete explosion, was necessary to the operation of the breeder plant. To split the first uranium nucleus by bombarding it with neutrons from the beryllium target took more power than the death of the atom gave up. In order that the breeder pile continue to operate it was imperative that each atom split by a neutron from the beryllium target should cause the splitting of many more.
It was equally imperative that this chain of reactions should always tend to dampen, to die out. It must not build up, or the uranium mass would explode within a time interval too short to be measured by any means whatsoever.
Nor would there be anyone left to measure it.
The atomic engineer on duty at the pile could control this reaction by means of the “trigger”, a term the engineers used to include the linear resonant accelerator, the beryllium target, the cadmium damping rods, and adjacent controls, instrument board, and power sources. That is to say he could vary the bombardment on the beryllium target to increase or decrease the level of operation of the plant, he could change the “effective mass” of the pile with the cadmium dampers, and he could tell from his instruments that the internal reaction was dampened-or, rather, that it had been dampened the split second before. He could not possibly know what was actually happening now within the pile-subatomic speeds are too great and the time intervals too small. He was like the bird that flew backward; he could see where he had been, but never knew where he was going.
Nevertheless, it was his responsibility, and his alone, not only to maintain the pile at a high efficiency, but to see that the reaction never passed the critical point and progressed into mass explosion.
But that was impossible. He could not be sure; he could never be sure.
He could bring to the job all of the skill and learning of the finest technical education, and use it to reduce the hazard to the lowest mathematical probability, but the blind laws of chance which appear to rule in sub-atomic action might turn up a royal flush against him and defeat his most skillful play.
And each atomic engineer knew it, knew that he gambled not only with his own life, but with the lives of countless others, perhaps with the lives of every human being on the planet. Nobody knew quite what such an explosion would do. A conservative estimate assumed that, in addition to destroying the plant and its personnel completely, it would tear a chunk out of the populous and heavily traveled Los Angeles-Oklahoma Road-City a hundred miles to the north.
The official, optimistic viewpoint on which the plant had been authorized by the Atomic Energy Commission was based on mathematics which predicted that such a mass of uranium would itself be disrupted on a molar scale, and thereby limit the area of destruction, before progressive and accelerated atomic explosion could infect the entire mass.
The atomic engineers, by and large, did not place faith in the official theory. They judged theoretical mathematical prediction for what it was worth-precisely nothing, until confirmed by experiment.
But even from the official viewpoint, each atomic engineer while on watch carried not only his own life in his hands, but the lives of many others-how many, it was better not to think about. No pilot, no general, no surgeon ever carried such a daily, inescapable, ever present weight of responsibility for the lives of others as these men carried every time they went on watch, every time they touched a venire screw, or read a dial.
They were selected not alone for their intelligence and technical training, but quite as much for their characters and sense of social responsibility. Sensitive men were needed-men who could fully appreciate the importance of the charge entrusted to them; no other sort would do. But the burden of responsibility was too great to be borne indefinitely by a sensitive man.
It was, of necessity, a psychologically unstable condition. Insanity was an occupational disease.
Doctor Cummings appeared, still buckling the straps of the armor worn to guard against stray radiation. “What’s up?” he asked Silard.