1942 – Leipzig, Germany, L-IV Atomic Pile Melts Down

"June 23, 1942 – Leipzig, Germany (then Nazi Germany) – Steam explosion and reactor fire*

Shortly after the Leipzig L-IV atomic pile — worked on by Werner Heisenberg and Robert Doepel — demonstrated Germany's first signs of neutron propagation, the device was checked for a possible heavy water leak. During the inspection, air leaked in, igniting the uranium powder inside. The burning uranium boiled the water jacket, generating enough steam pressure to blow the reactor apart. Burning uranium powder scattered throughout the lab causing a larger fire at the facility.[1][2]"

http://en.wikipedia.org/wiki/List_of_military_nuclear_accidents

End

1942 – Leipzig, Germany,  L-IV Atomic Pile Melts Down; via @AGreenRoad
http://agreenroad.blogspot.com/2014/04/1942-leipzig-germany-l-iv-atomic-pile.html