Worst Lab Accidents in History
Criticality Accidents

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"Critical mass" is achieved when a radioactive substance is present in the proper amount to create a sustained nuclear chain reaction. Thus, as Maggie Koerth-Baker succinctly describes, a "criticality accident" is a "nuclear reaction happening where and when you don't want it to." Nuclear reactions are dangerous because they release radiation, either in the form of particles (such as alpha and beta particles) or high-energy electromagnetic radiation (such as gamma rays).

Cecil Kelley, who worked at a plutonium processing facility at Los Alamos National Laboratory, was exposed to a lethal dose of neutrons and gamma rays in merely 200 microseconds when a large mixing tank containing plutonium accidentally went critical. Kelley fell to the floor and began screaming, "I'm burning up!"

The details of his excruciating death are reproduced below:

The symptoms Kelley displayed at the plutonium-processing facility, characterized by collapse and mental incapacitation, were the first stage of his clinical course... The second stage began when he arrived in the emergency room of the Los Alamos Medical Center. It was dire. Kelley was semiconscious, retching, vomiting, and hyperventilating. His skin was cold and dusky reddish-violet, and his lips had a bluish color that indicated poorly oxygenated blood.


One hour and forty minutes after the accident, Kelley entered the third stage, which was both the longest and most encouraging. Kelley regained coherence, and although he complained of severe abdominal cramps and occasionally retched and vomited, he seemed considerably improved overall... Because Kelley had been irradiated with neutrons, the sodium and other light metals in his blood were “activated,” or transformed into radioisotopes such as sodium-24. His average whole-body dose was first estimated by measuring the radioactivity of his blood. It appeared to have been massive—in the range of 900 rad from fast neutrons and 2,700 rad from gamma rays, giving a total of 3,600 rad—and certainly lethal.


Six hours after the accident, the lymphocytes virtually disappeared from Kelley’s peripheral circulation, which was taken as a grave sign.


During the second evening after the accident, Kelley entered the fourth stage. The pain in his abdomen became difficult to control. He became increasingly restless despite medication—so much so that the intravenous infusions were inadvertantly interrupted. He began to sweat profusely, his color became ashen, and his pulse irregular. About 35 hours after the accident, Kelley died.

Unfortunately, there have been several such criticality accidents throughout history.

Source: Federation of American Scientists (PDF)

Image: Wikimedia Commons

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