Is it possible to build a nuclear reactor at home? The story of David Hahn, who went down in history as the radioactive scoutshows how dangerous and unrealizable this idea is, but also incredibly real. In the United States of the 1990s, a teenager managed to push himself beyond all limits, attempting to assemble an experimental nuclear reactor in his parents’ shed, using radioactive materials recovered from everyday objects.
David Hahn’s project
In 1994 David Hahn, a young American boy scout, decided to build a miniature nuclear reactor surge generator inside the family cabin. His objective was not only theoretical: Hahn wanted to demonstrate that a reactor of this type could produce electricity and generate new fuel, following the principles of nuclear fission, which he considered more accessible than fusion.
The boy was openly inspired by the great names in physics between the end of the nineteenth century and the first half of the twentieth century, such as Antoine Henri Becquerel, James Chadwick, Frédéric Joliot-Curie, Irène Joliot-Curie and above all Enrico Fermi, author of the first self-sustaining nuclear chain reaction. Unlike his models, however, Hahn did not have state funding, certified laboratories or any legal authorization.
Radioactive materials recovered from common objects
To assemble his reactor, David Hahn managed to obtain americium, radium, thorium and tritium, radioactive substances extracted from everyday objects. Smoke detectors contain about 0.2 milligrams of americium-241, while old phosphorescent paints on watches are rich in radium. Gas lantern mantles provided thorium, and some firearm sights contained up to 1.2 micrograms of tritium (hydrogen-3).
To purify thorium, Hahn even used lithium extracted from a battery, manually cut with pliers. According to an investigation published in Harper’s Magazine, many of these items were stolen illegally, as the young man had no legal way to obtain radioactive materials. Everything was handled without shielding, without cooling systems and without personal protection, in simple improvised containers.
Because the nuclear reactor never reached critical mass
David Hahn’s domestic nuclear reactor never managed to reach critical mass, an indispensable condition for triggering a self-sustaining nuclear reaction and producing energy. In a functioning reactor it is necessary to slow down and control the neutrons, keeping fission fast enough to self-sustain, but not so fast that it becomes uncontrollable.
An extremely complex balance, even more difficult to obtain in a small system. Added to this are the need for adequate shielding against radiation and constant cooling, elements completely absent in the scout’s design. Hahn only managed to go so far as to build a neutron generator, before his activities attracted the attention of the authorities.
The discovery came about completely by chance. During a check, police found radioactive materials in the trunk of David Hahn’s car, prompting authorities to investigate the situation. Inspection of the parents’ shed revealed extremely dangerous levels of radioactivity, with high concentrations of americium-241 and thorium-232.
A simple can of preserves recorded up to 50,000 pulses per minute, a value about a thousand times higher than the normal natural background of radiation. Faced with this data, the entire structure was dismantled. All contaminated objects, along with the mini-reactor, were classified as radioactive waste and buried in the Utah desert, under the supervision of state authorities.
Having become a small celebrity for this incredible and disturbing story, David Hahn died in 2016, at the age of 39. His story remains one of the most extreme examples of scientific fascination taken beyond the limits, concretely demonstrating why building a nuclear reactor at home is not only impossible, but profoundly dangerous.
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