1) On this day, in 2000, the reactor number 3 of the Chernobyl nuclear power plant was shut down for good. Yes, you got it right; Chernobyl wasn't closed after the accident in 1986 - the reactor number 4, where the accident happened, was of course shut down (it was completely destroyed), but the other reactors continued to operate. Reactor number 1 ran until 1997, number 2 until 1991, and number 3 until 15th of December 2000. (Read more about the shutdown of the Chernobyl NPP HERE)
2) Today is also the birthday of Henri Bequerel - the discoverer (together with Marie and Pierre Curie) of radioactivity. He got the Nobel Prize in physics for this discovery, in 1903, just five years before he died. It was just an accident that he, in 1897, actually discovered that uranium salts emit some kind of radiation - a penetrating type of radiation that could be registered on a photographic plate. Bequerel wanted to, and first thought that he was studying a type of X-rays, but the radiation that came from the uranium salts turned out to be the new phenomenon called radioactivity 🙂 (If was actually spontanious radioactivity that he discovered; radioactivity can also be induced - if a material is bombarded with for example neutrons it can become radioactive, and this discovery was done by Irène Curie and Frédéric Joliot-Cuire.)