Uranium was discovered in 1789 by Martin Klaproth, a German chemist.

In 1896, Wilhelm Rontgen discovered ionizing radiation.

Henri Becquerel detailed even further in 1896 demonstrating beta radiation and alpha particles coming out of ore containing radium and uranium.

Pierre and Marie Curie went further by isolating the components and calling the process radioactivity.

In 1989 Samuel Prescott showed that radiation destroyed bacteria in food.

In 1902 Ernest Rutherford showed the details at a particle level with radioactivity emitting an alpha or beta particle from the nucleus and in 1919 he fired alpha particles into nitrogen causing nuclear rearrangement.

In 1911 Frederick Soddi discovered different isotopes of radioactive elements.

In 1932 Cockcroft and Walton produced nuclear transformation by bombarding atoms with protons.

In 1935 Enrico Fermi found that a much greater variety of artificial radionuclides could be formed when neutrons were used instead of protons.

In 1939 Hahn and Strassmann fission not only released a lot of energy but also released additional neutrons which could cause fission in more uranium nuclei.