nuclear-news

Plutonium’s deadly history

The Manhattan Project’s Fatal “Demon Core”, Physics Central, May 21, 2012 Sixty six years ago today, Louis Slotin saw a flash of blue light in the depths of Los Alamos National Laboratory. Seconds before, all that separated the young scientist from a lethal dose of radiation was a thin screwdriver.

The screwdriver supported a reflective covering that encased a sphere of plutonium, and if the reflector fell into place, a nuclear chain reaction would commence. When Slotin’s hand slipped, a lethal burst of radiation hit him, and he died nine days later.

One year later, the U.S. military detonated this plutonium “demon
core” at the Bikini Atoll in the Pacific Ocean. But the legacy of the
demon core — and its victims — has endured.
Slotin was not the demon core’s first victim before it was detonated
in the Pacific. Harry K. Daghlian Jr., another Los Alamos scientist,
died after a strikingly similar accident in 1945. Alone in the
laboratory, Daghlian was conducting an experiment on the plutonium
sphere. By itself, the sphere did not have enough mass to start a
nuclear chain reaction. With some help from a reflective material,
however, the plutonium could start such a chain reaction.

During a chain reaction, the nuclei of radioactive atoms split,
releasing neutrons. These neutrons join other atoms; these new atomic
nuclei begin splitting; and more neutrons are released. By adding a
reflective material that sends these neutrons back toward the atomic
nuclei, scientists could initiate a chain reaction with smaller
amounts of plutonium.

Daghlian was conducting tests on this phenomenon when he accidentally
dropped too much reflective material onto the plutonium, leading to a
burst of radiation that ultimately killed him 30 days later.

One year after this accident, Slotin conducted a very similar
experiment, but he had an audience. Slotin was showing his work to
several other scientists in the room while holding a hemisphere
reflective material over the top of the demon core. When the
screwdriver that supported the reflector slipped, a huge burst of
radiation was emitted.

After both of these incidents, Los Alamos forbade all related hands-on
testing, and researchers used a remote facility to control the
experiments. These early experiments highlighted the slim margins for
safety in nuclear physics…..

May 23, 2012 - Posted by Christina Macpherson | - plutonium, history, Reference