The "Oops" Heard 'Round the World (Or Not)
In the last week, I have managed to burn one knuckle on each finger, two fingertips, the palm of one hand and the back of the other. My hands, more or less, look like I washed them in napalm. I could, of course, blame all this on the fact that I've had to use the deep fryer at work more often than usual the last few days, but even if I didn't go anywhere near a tub of boiling oil, I'm sure I would have managed to find a way to hurt myself.
You see, I'm a klutz. And that's why today we're going to talk about one of my brothers in arms, a fellow klutz. Quite possibly the most infamous klutz in American history.
Harry K. Daghlian, Jr. had spent most of the summer of 1945 working as an assistant in the preparation of a plutonium core for the Trinity nuclear bomb test in Alamogordo, NM. The tests were successful, and in August he was moved to the Los Alamos Omega site, where he assisted with a series of experiments concerning the critical masses of a 13.6 pound sphere of plutonium in various tungsten carbide tamper arrangements. In these experiments, the tungsten bricks were slowly added around the core as neutron reflectors, serving to reduce the mass required for the plutonium to go critical. Eventually, enough bricks would have been added to allow the assembly to go into a controlled critical nuclear reaction, basically becoming a miniature nuclear reactor.
On the morning of August 21, Daghlian constructed a cube of tungsten carbide bricks around the plutonium sphere on a square base measuring 14-7/8 inches per side (photo below is from a re-creation of the experiment). He noted that the assembly was found to be critical when five layers of bricks were completed and two additional bricks were placed in the middle of a sixth layer. That afternoon, he constructed another cube around the plutonium, this time on a 12-3/4 inch square base. Criticality was achieved when five layers of bricks were completed, it was a smaller, more efficient assembly. As he disassembled the materials and returned the plutonium to its vault, Daghlian began planning the next criticality experiment and decided to he would construct the next assembly on a 10-5/8 inch square base. He then went to dinner and a lecture at the site's theater, during which he decided to return to the lab that evening to continue the tests, rather than the next morning as originally planned.
Daghlian had been working in the government labs for some time at this point, and was no doubt well aware that his decision to perform a potentially hazardous experiment alone and after-hours violated official safety regulations. His mind was made up, though, and he returned to the lab at 9:30 that night. He removed the plutonium from the vault and, using the clicks of a Geiger counter as a guide, completed four-and-a-half layers on the new assembly. As he went to place another brick in the fifth layer, the increasing clicks alerted him that this brick would cause the assembly to go supercritical, meaning an increasing rate of fission, as opposed to the equilibrium fission of the critical state. A supercritical mass, as we'll see, is not a good thing.
He immediately withdrew the hand holding the brick, but was struck by an ill-timed case of butterfingers. He dropped the brick into the center of the assembly. He instinctively pushed the brick away from the assembly with his right hand, which immediately became enveloped in the blue glow that was now surrounding the plutonium.
At 9:55, Daghlian partially disassembled the experiment and went to the hospital to have someone look at his tingly, glowing blue hand.
Daghlian received a total-body radiation exposure of approximately 480 roentgens (the unit of measurement for ionizing radiation) of soft x-rays and 110 roentgens of gamma rays. Because of the way the accident happened, though, the distribution of radiation wasn't uniform. His left hand, which dropped the brick, received 5,000 to 15,000 rem (rÃ¶ntgen equivalent in man, the unit of measurement for a radiation dose), and his right hand, which he used to push the brick away, received 20,000 to 40,000 rem. Let's put that in perspective: most charts explaining exposure levels and their corresponding symptoms describe 5,000 rem as 100% fatal and don't go any further. Harry was, to say the least, in bad shape.
During the 25 remaining days of his life, Daghlian experienced swelling and numbness in his hand, unrelenting nausea, repeated bouts of retching and vomiting, prolonged episodes of hiccups, hair loss, reddening of both forearms, neck and face and a progressive loss of skin layers. On September 15, 1945, Daghlian went into a coma and died at 4:30 PM.
Los Alamos issued a press release that said Daghlian died from "chemical burns," rather than radiation poisoning. This little bit of information manipulation transformed Daghlian from America's first nuclear casualty into an obscure footnote in history (at least until Wikipedia came along). But, like me, he was a bit of a klutz; and for that, we salute him.