He created a low power neutron source. Such sources can be created at home, for example: https://en.wikipedia.org/wiki/Fusor

He hoped to create a breeder reactor, but he was very far creating a working breeder reactor.

Also:

"EPA scientists believed that Hahn's life expectancy may have been shortened due to his exposure to radioactivity, particularly since he spent long periods in the small, enclosed shed with relatively large amounts of radioactive material and only minimal safety precautions, but he refused their recommendation that he be examined at the Enrico Fermi Nuclear Generating Station."

Kids, don't play with Americium.