"for better or worse" - The worlds first manmade nuclear chain reaction, 75 years on.


Leo Szilard, who came up with the idea for creating a manmade nuclear chain reaction thought during the construction of the reactor under the stands of the University of Chicago's Stage Field in a disused squash court that the experiment "would go down as a black day in the history of mankind".


The year was 1942, the date 2nd December and it was the coldest day in Chicago for 50 years. As part of the infamous Manhattan Project with the ultimate aims of figuring out how to control nuclear energy (before Germany did) and prevent the reaction from spiralling out of control. The data from this experiment was used to produce the plutonium that was used in the atomic bomb that was dropped on Nagasaki.

The team of 50 scientists working on the project were an interesting bunch to say the least. They included the nobel prize winning director, Arthur Compton, the Hungarian born Eugene Wigner - who reportedly sneaked in a bottle chanti into the facility which was drank in paper cups upon sucessful completion of the experiment. There was Enrico Fermi who was known as "Italian navigator" and the aforementioned Leo Szilard who originated from Hungary. Due to the ongoing World War II many of the team, including those above, were seen as "alien enemies" and deemed a security risk. This eventually resulted in the majority of the team being moved to Los Alamos in New Mexico.


The Chicago Pile was a pile of forty thousand graphite blocks, held together in a wooden frame, twenty-five feet wide and twenty feet tall. Inside about half of the blocks were holes containing small amounts of uranium oxide; inside a few others were nuggets of refined uranium metal, the production of which was still a novel process. The Pile had few safety features. The scientists’ only protection against radiation came from a set of cadmium control rods, designed to be inserted and removed by hand. As one governmental report later put it, “there were no guidelines to follow and no previous knowledge to incorporate.” Neither university nor city officials were told that an experiment that even its creators judged as risky was taking place in the heart of the second-largest city in the United States.

The experiment itself latest only around 30 minutes. The pile was brought to criticality (the point at which a nuclear reaction becomes self-sustaining), then shut down half an hour later, before its growing heat and radioactivity became too dangerous.


The equipment was experimented with it for a few months before disassembling and reconstituting it—now with radioactive shielding—at a site somewhat more removed from the city, where it became known as Chicago Pile-2. Ultimately, the reactor ran for over a decade before it was finally dismantled and buried in the woods.


The 2nd December 1942 is clearly marked as starting point of the Nuclear Era, or "nucleonics" as it was being coined at the time. Now, 75 years later in time we are now on the cusp of the Nuclear Renaissance and given the right course, nuclear technology, testing innovative ideas in nuclear energy with new concepts in advanced nuclear energy, such as “small modular reactors”—small-sized enclosed reactors that may offer security, cost and economic advantages over full-sized plants.

References and further information:

  • https://www.newyorker.com/tech/elements/remembering-chicago-pile-worlds-first-nuclear-reactor

  • https://www.theatlantic.com/science/archive/2017/12/75-years-nuclear-reactor/547151/

  • http://www.pbs.org/wgbh/nova/next/military/first-nuclear-chain-reaction-changed-the-world-75-years-ago-today/

  • https://news.uchicago.edu/article/2017/12/02/former-us-energy-secretary-moniz-caps-first-day-nuclear-reaction-commemoration

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