Voyage of the Devilfish

The main detonator of the Magnum’s warhead was set in motion by a spark cap, making the thumb-sized high explosive burn into a white-hot miniature fireball. In turn the main detonator caused six larger igniters to explode within ten microseconds of each other. Each of the six igniters then caused its pie-shaped trinitrotoluene charge to detonate. The points of the pie-shaped charges faced the center of the forward section of the Magnum torpedo, and the charges went up in one coordinated explosion. More accurately it would be called an implosion, since the shaped charges were designed to cause a pressure pulse to move inward, toward the center of the torpedo. As the explosives at the skin of the warhead blew inward they forced a doughnut-shaped piece of plutonium to collapse into a dense sphere, the mass blown into the hole of the doughnut. As the plutonium collapsed into a dense ball from the force of the explosion it achieved critical mass. There had long been a background of nuclear fissions, the splitting apart of the heavy plutonium atom’s nuclei, ever since the plutonium had been assembled into the Magnum torpedo a year before, but each fission had sent its neutrons flying off into space. The leaking neutrons were lost forever, and continued to leak out of the doughnut, useless in causing any further fissions. And although each fission gave off a tremendous amount of energy, the fissions were sporadic, infrequent. But as the plutonium was blown into a dense ball, the critical mass, the neutrons stopped leaking. The sporadic fissions still happened but each neutron flew not out into space but directly into another plutonium atom’s nucleus, splitting that nucleus into two smaller isotopes and sending out another three neutrons. And as those three flew away from the fissioning atom they didn’t leak but collided with other plutonium nuclei in the densely packed mass. And each of the three neutrons of that fission generation created three more fissions, with three more neutrons. Those three caused nine new fissions, creating 27 neutrons that led to 81 fissions, then 243, then 729, then 2187, until after 47 generations of fissions nearly every molecule of plutonium present had experienced an energy-releasing fission. The whole process took less than fifty microseconds. The result was a nuclear explosion, a fission bomb. Even so, it was only the beginning. The original plutonium doughnut had been surrounded with a canister of deuterium, heavy water. The fission explosion was a trigger for the fusion reaction, giving the deuterium atoms’ nuclei enough energy to come together and form a heavier element, helium, releasing even greater quantities of energy per reaction. The deuterium atoms experienced fusion on an incredible scale, forming the helium and bringing the area in the vicinity of what was once the Russian Magnum torpedo to the temperature of the sun’s surface, several million degrees. The icecap itself, 600 meters above, over 30 meters thick, jumped into the air. A series of cracks in the ice formed, some as far as 70 kilometers from the blast. The ice immediately above the blast zone was blown hundreds of meters skyward in a tower of steam. The sphere of million-degree gas expanded rapidly, growing hundreds of meters in diameter. But even the hydrogen bomb had met its match in the coldness and near-infinite stretches of frigid ocean water. As the gas cloud expanded at high pressure, the cold arctic water cooled it, calmed it and eventually collapsed it. The gas bubble, defeated by the cold arctic sea, gave up and decomposed into several hundred trillion bubbles, all rising upward in the radioactive water that had rushed back in to fill in the hole left by the explosion.