Extrato
The Acid Taste of Plutonium
The accident occurred on August 1, 1944, a morning like any other in Los Alamos: hot, dry, the sky an indigo bowl over the sprawl of wooden buildings and barbed-wire fences that constituted the core of the Manhattan Project. At seven thousand feet, the New Mexico air smelled of sun, pines, a trace of frost. Occasionally the scent of dust spiraled up from the desert, where temperatures hovered around 100 degrees.
In twelve months, two atomic bombs would be dropped on Japan, and the secret work being carried out in the wooden buildings would be revealed to the world. On the morning of the accident, the atomic bomb had progressed far beyond mathematical theories but was still an unproven weapon. Plutonium, a silvery metal discovered about four years earlier, was one of the key elements that would transform the theories into a fireball.
In Room D-119, a cheerful young chemist named Don Mastick was standing over a sink chatting with his laboratory partner, Arthur Wahl, a chemist not much older than himself and one of the four scientists from the University of California at Berkeley who had discovered plutonium. Mastick was just twenty-three years old, a "bushy-tailed kid," as he would later describe himself, with short blond hair and an alert, friendly face. He had been one of Berkeley's most promising chemistry graduates and was just about to enlist in the Navy when J. Robert Oppenheimer approached him and asked if he would like to join the scientific team being assembled in Los Alamos, the most secret site in the vast network of laboratories and factories established to build the bomb.
Oppenheimer, a brilliant theoretical physicist, was already a legend on the Berkeley campus, and Mastick was thrilled at the idea of working with him. When he arrived in Los Alamos in the spring of 1943, Oppenheimer had designated him the lab's ultra microchemist. Working with amounts of plutonium that were too small to be seen with the naked eye, he studied the chemical reactions of the new material under a microscope. His glass test tubes were no bigger than sewing needles and his measuring instruments looked like a child's toys. Even his laboratory was small: a claustrophobic box at the end of a hallway, ten feet wide and twelve feet long.
In Mastick's hand that day was a small vial containing ten milligrams of plutonium--an amount so small it would have fit on the head of a pin. But it was far more plutonium than Los Alamos had had to work with only a year before. In fact, the radioactive material was still so scarce that a special crew had been assembled whose only job was to recover the material from accidents and completed experiments and then repurify it through chemical processes so it could be used again. The crew developed a flow chart to help separate plutonium from every other element in the Periodic Table. "They were prepared to tear up the floor and extract the plutonium, if necessary. They would even dissolve a bicycle. I mean, plutonium [was] so valuable that they went to great extremes to recover everything," physician Louis Hempelmann recalled decades later.
Inevitably some of the radioactive molecules seeped out into the laboratory, spread by a starched sleeve, the scuff of boots, even the dust that blew in from the desert. Nervous and preoccupied with their efforts to construct a workable bomb, Oppenheimer and his colleagues viewed the spreading contamination with consternation. Their concerns were twofold: They didn't want to lose any material, and they were just beginning to understand its potential hazards. Joseph Kennedy, another member of the Berkeley team who had discovered plutonium, acknowledged that it was "not pleasant" to think that unaccounted-for plutonium was floating around the lab. On the day of this particular accident--which would be the most serious of any thus far--it was not the lost plutonium that would be the problem. It was the plutonium in Mastick's vial.
A purplish-color liquid that gave off an eerie, animallike warmth when concentrated in larger amounts, the plutonium in the vial had undergone an unanticipated transformation overnight. Some of the liquid had been converted into gas and was pushing against the walls of the bottle. Other molecules were tunneling into the sides of the glass itself.
Unaware of the small bomb he was holding, Mastick snapped the slender neck of the vial. It made a small, popping sound in the quiet laboratory. Instantly the material spewed out of the bottle and onto the wall in front of him. Some of the solution ricocheted back into his mouth, flooding his lips and tongue with a metallic taste.
Not overly alarmed, Mastick replaced the vial in its wooden container. Then he trotted across the hard-packed ground of the technical area to knock on the door of Dr. Hempelmann's first-aid station. He had just swallowed a significant amount of the world's supply of plutonium. "I could taste the acid so I knew perfectly well I had a little bit of plutonium in my mouth," he said in an interview in 1995.
Louis Hempelmann's office was just a few minutes' walk from D Building, where Mastick worked. With its "deluge shower baths" and clothes-changing rooms, D Building was one of the most elaborately ventilated and costly structures at Los Alamos. Except for the forest of metal pipes protruding from the roof, it looked no different from the other green clapboard structures in the technical area.
Hempelmann was the medical doctor in charge of protecting technical personnel on the bomb project from "unusual hazards," and he reported directly to J. Robert Oppenheimer. With his long, narrow face and wide jaw, Hempelmann wasn't handsome, but there was something refined and pleasing about his appearance. He was the son and grandson of doctors and a fine physician in his own right, although he was known to grow queasy at the sight of blood. ("Louie did his first sternal puncture on me and he almost fainted. He's one of those doctors that can't stand the sight of blood--he should have been a psychologist or something," said Harold Agnew, one in a line of laboratory directors who succeeded Oppenheimer.)
Taking great pains to keep his long face expressionless, Hempelmann listened to Mastick's account of what had happened and then left the room for a moment in order to make a frantic phone call to Colonel Stafford Warren, the affable medical director of the Manhattan Project. Hempelmann often turned to Warren, who was nearly two decades older, for advice and reassurance. In his late forties when he was commissioned as an Army colonel, Warren was a big man, well over six feet tall, who exuded a breezy confidence. Unlike many of the scientists on the bomb project, who refused to join the armed forces and chafed under military control, Warren loved being in the Army. He liked the rough feel of his starched uniform, the silver eagles on his collar, the .45 revolver tucked in a holster on his belt.
Speaking on a secure telephone line from his office at the Manhattan Project's headquarters in Oak Ridge, Tennessee, Warren tried to calm Hempelmann down. He thought about the accident for a moment and then suggested that the young doctor try using a mouthwash and expectorant to remove the plutonium from the chemist's mouth. Hempelmann hung up and hurried back to the examining room where he prepared two mixtures. The first was a sodium citrate solution that would chemically combine with the plutonium in Mastick's mouth to form a soluble liquid; the second was a bicarbonate rinse that would render the material insoluble again.
Mastick swished the solutions around in his mouth and then spit them into a beaker. The first mouthful contained almost one-half microgram of plutonium. A microgram of plutonium, which is a millionth of a gram, was considered in 1945 to be the maximum amount of plutonium that could be retained in the human body without causing harm. Eleven more times at fifteen-minute intervals Mastick swished the two solutions around in his mouth and then spit them into the beaker.
After the accident, Mastick's breath was so hot that he could stand six feet away and blow the needles on the radiation monitors off scale. His urine contained detectable plutonium for many years. In one of several interviews Mastick said that he was undoubtedly still excreting "a few atoms" of plutonium but had suffered no ill effects.
When the mouth washings finally were finished, Hempelmann ordered the young man to lie down on a cot. Then he pumped out his stomach several times. Carefully he transferred the stomach liquids into a tall beaker. The plutonium would have to be chemically separated from the organic matter in Mastick's stomach and mouth so it could be reused in future experiments. No scientist at the lab had ever undertaken such a task.
Hempelmann gave the young chemist a couple of breakfast waffles for his empty stomach and some Sippy alkaline powders to be taken during the day. Then he turned and handed him the four-liter beaker of murky liquid.
Go, he said, retrieve the plutonium.
Mastick returned to his lab with the beaker and opened his textbooks. It took a "little rapid-fire research," as he put it, to figure out how to separate the plutonium from the organic matter. But he didn't flinch from the task, despite the ordeal he had just been through. "Since I was the plutonium chemist at that point, I was the logical choice to recover it." From Mastick's perspective, the mood in which all these events took place was calm, deliberate, and "almost humorous." But other people did not feel nearly so relaxed about what had occurred.
The day after the accident, Hempelmann sat down and wrote Stafford Warren a thank-you note. "I was sorry to bother you but was anxious to have your help and moral support. In retrospect, I think that the chances of the fellow's having swallowed a dangerous amount of material are slight." Hempelmann told Warren that he believed about ten micrograms of plutonium had entered Mastick's mouth. The mouth washings had removed all but one microgram, an infinitesimal but nevertheless hazardous amount. More important, Hempelmann thought the chemist had not inhaled any plutonium. At that time scientists knew that plutonium was extremely hazardous if it was breathed in and deposited in lung tissue. But they also were discovering that the radioactive material was not readily absorbed through the gastrointestinal tract and that it could not penetrate beyond the outer layer of human skin. Thus, most of the microgram of plutonium in Mastick's mouth undoubtedly would have passed through his digestive system and out of his body without being absorbed.
A catastrophe had been avoided, but the accident was a vivid reminder of the invisible dangers that scientists and workers were confronted with at "Site Y," the code name for Los Alamos. The responsibilities seemed overwhelming to Hempelmann, who was only twenty-nine years old and a neophyte when it came to understanding radiation. He had been working with radioactive materials for three years. As for plutonium, he had only about six months of hands-on experience. "There were all sorts of problems," he admitted years later, "which I just couldn't handle because of limited experience."
