It was not your average industrial fire. In the black smoke the plutonium and the magnesium were burning furiously, and the room was lighted up like a new shopping center opening, even as the fluorescent lights melted and came crashing down on the firemen. Molten lead from the gamma-ray shielding was hitting the floor in globs, and even the glue used to hold the Benelex together was on fire. The Styrofoam in the roof started melting, and the tar on top was getting soft. The powerful blowers were pulling air through the wall on the second floor, just as they were supposed to do, and the filters were already burning. All seemed lost when, in a miraculous stroke of good fortune, a fireman accidentally backed a truck into a power pole and killed the electricity to the building. The fans squeaked to a stop.
Firefighters in full radiation gear were now able to enter the room without being incinerated by the air-fed flames.[167] They came into the crowded space spraying water, and when they moved from line to line, they had to go under, using the sheep dips. The ravines were now filled with water, so it was like wading through a creek in a space suit, up to your chest. The firemen noticed that the oxidized plutonium powder stuck together when wet, like gray Play-Doh. They tried to corral it into a corner using the high-pressure hoses. Fortunately it was too sticky, and it clung to the floor. If they had been able to push it with the hoses as they desired, it would have assumed a critical shape and killed them all with an unshielded supercriticality.
By 8:00 P.M., the fire was declared not burning, but the wet plutonium was still flaring up as late as Monday morning. The AEC investigated the cause of the accident, and its report, criticizing both itself and Dow Chemical for allowing obvious safety lapses, was classified SECRET. With $70.7 million in damages, it broke the record for industrial loss in a fire in the United States. The report from the fire in 1957 had apparently not been read, possibly because it too was SECRET, and no lessons had been learned and applied to preventing further plutonium fires. There were no injuries, and no wind-borne contamination of the surrounding area was detected. Connected Buildings 776–777 were turned into a large parking lot.
By 1992, the mission of Rocky Flats, to fabricate nuclear weapon components, had completely dried up. The Cold War was over, and the last remaining fabrication job, making cores for the W88 “Trident II” submarine missiles, reached the end-of-contract. Of the 8,500 workers, 4,500 were laid off permanently and 4,000 were kept on for cleanup. In 2001, the Rocky Flats National Wildlife Refuge Act of Congress turned the bomb factory site into a nature park. It was amazing, but in three decades of difficult work at Rocky Flats using a great deal of a very dangerous material, plutonium, nobody died in an accident. The work was so secret, negative publicity from it could not do much damage to the public perceptions of radiation and nuclear energy release.
The parts built at Rocky Flats, Colorado, were shipped to the Pantex bomb assembly plant, about 17 miles northeast of Amarillo, Texas, to be made into nuclear weapons. Before 1942, Pantex was a large, 16,000-acre, utterly flat wheat field; but with the pressing need for bombs to drop in World War II, an ordnance factory was built on the site. For the next three years, thousands of workers loaded gravity bombs and artillery shells with TNT. It was dangerous work, and an unusual amount of care was needed to keep from accidentally blowing everything up. The pay was good, but there was no smoking. All nicotine-delivery systems had to be held in the mouth, closed, and chewed. At the end of the war, on VJ Day, the plant was deactivated, and the workers had to find something else to do.
In 1951, the AEC had a sudden need for a centralized plant in the middle of nowhere to manufacture atomic bombs, and the old Pantex site was ideal. The original buildings were expanded and refurbished for $25 million. Proctor & Gamble, expert at making shampoo and laundry detergent, was put in charge.[168] The metal parts for the bombs, including the fissile material, were built elsewhere, but at Pantex the chemical explosives used to set off the nuclear detonations were cast and machined to fit, as if they were made of plastic.
The nuclear weapons used by the United States were almost all “implosion” types, in which the fissile material is forced into a hypercritical configuration using a hollow sphere of high explosives. The shell of explosive material is assembled from curved segments, like a soccer ball. In a normal explosion of a sphere, such as a hand grenade, a detonator at the center of the explosive sets it off. The explosion starts at the point of detonation and moves rapidly outward in a spherical wave-front until the entire mass of explosive is burned up. The wave-front then proceeds outward, as a sphere of compressed gas moving outward very fast. The spherical wave grows larger and larger, and the energy imparted to it by the brief explosion becomes stretched thinner and thinner. Far enough from the explosion, it is no longer strong enough to knock you down, and the destructive explosion is reduced to a loud noise as the energy pulse is spread out over the entire surface area of the sphere.
The implosion works in reverse. Instead of being detonated from a point in the middle, the sphere of explosive must be detonated from its entire outer surface. There is still a spherical wave-front that starts at the surface heading away from the bomb, but this is a waste of energy. There are two wave-fronts. One heads out, and one heads in. Inside the sphere, the wave-front grows smaller and smaller as it heads for the center. The energy from the brief explosion, instead of being dispersed and losing impact, is concentrated down, losing nothing. At the center of the sphere is a small ball of plutonium. The converging wave-front hits it so hard, it bends the molecular forces that are maintaining its density, and it shrinks to a concentrated, smaller size. This new configuration makes it hypercritical. Flying neutrons do not have as far to travel to hit a nucleus, and with the nuclei crowded closer together, it becomes hard to miss. The ball explodes with a sudden release of nuclear power.
The problem is detonating the entire outer surface of the sphere all at once. It is not really possible to do so. The best you can do is to set off about 40 point-detonators placed around the outside of the explosive shell. These can be made to all go off at once, but the explosion does not make a perfectly spherical wave-front. To form this unacceptable, knobby wave-front into a perfect sphere does not require expertise in making hand grenades. It requires optics.
Optics is the art of taking a wave-front of light and warping it into a desired shape using the fact that light travels at different speeds in air and glass. When a light wave traveling in air hits clear glass, it must slow down, and if it hits at an angle, then it is bent, or refracted. Controlling the angle at which the light encounters the glass controls the refraction. This is accomplished by grinding the glass into a curved surface, specifically designed to bend the incoming wave-front into the desired shape. This is how telescopes, microscopes, and vision-correcting glasses are made.
The chemical explosives in an atomic bomb work exactly the same way. There are actually two, nested explosive shells. The outer shell, having the point-detonators, is a fast explosive, producing a high-speed shock wave. The inner shell is a slower explosive, making a lower-speed shock wave. The interface between the two shells is shaped in very specific ways to refract the segmented knobs of the outer shell explosion into a perfectly spherical shock wave in the inner shell, based on the difference in wave-speed in the two media. Explosion in the outer shell is caused by little firecracker-like detonators, and the inner shell is set off by the shock-wave from the outer shell hitting it. Shaping of the solid explosive segments to make this happen must be precise, and one must be careful not to impart a shock to the explosive while machining it.
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The danger from radiation in most situations aside from criticality is that broken skin, lungs, or the gastro-intestinal system can be contaminated with radioactive dust. You do not want to be inoculated with a long-term radioactive nuclide in small quantities. Wading into a mixed radiation field for a short time is not really what causes health problems, but having dust decay inside you for a long time is. For this reason, a radiation protection suit seals you up against any interaction with the environment. An airtight coverall with tape-sealed gloves and booties is standard, along with self-contained breathing apparatus and a full head-covering. It is not pleasant. You cannot scratch your nose.
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The Maintenance and Operations (M&O) contract for Pantex was reassigned to Mason & Hanger — Silas Mason Co., Inc., Mason Technologies, Inc., in 1956. Mason & Hanger was the oldest engineering and construction company in the United States, dating back to 1827 in Virginia, and they had a lot of experience in managing ammunition plants.