This article lists notable military accidents involving nuclear material. Civilian accidents are listed at List of civilian nuclear accidents. For a general discussion of both civilian and military accidents, see nuclear and radiation accidents. For other lists, see Lists of nuclear disasters and radioactive incidents.
Scope of this article In listing military nuclear accidents, the following criteria have been adopted: There must be well-attested and substantial health risks associated with nuclear materials; or, it must involve nuclear weapons (even if lacking an installed fissile core or if nuclear detonation was not possible). To qualify as "military", the nuclear operation/material must be principally for military purposes. To qualify as "accident", the damage should not be intentional, unlike in nuclear warfare.
This list may be incomplete due to military secrecy.
1940s
Date Location Type Description June 23, 1942 Leipzig, Nazi Germany Steam explosion and reactor fire Leipzig L-IV experiment accident: 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.R. Döpel (1941 bzw. 1942), Beschreibung zweier Unfälle mit Uranoxid. February 11, 1945 Los Alamos National Laboratory, Los Alamos, New Mexico, United States Accidental criticality During an experiment with the Dragon machine (a "fast burst" criticality experiment designed by Otto Frisch), uranium hydride cubes were used in increasingly larger amounts. During the final experiment, 1015 fissions were produced, blistering and swelling the cubes by approximately 1/8th of an inch. No personnel were injured. June 6, 1945 Los Alamos National Laboratory, Los Alamos, New Mexico, United States Accidental criticality A pseudosphere of 35.4 kg of highly enriched uranium (enriched to an average of 79.2% U-235) was put inside of a polyethylene box, and the box put into a tank that was filled with water. Before the tank was filled, the system unexpectedly went critical. An estimated 3-4×1016 fissions occurred and the temperature of the metal may have risen to 200 °C. Several personnel were exposed to non-lethal amounts of radiation, and the material was re-used for experiments within days. August 21, 1945 Los Alamos National Laboratory, Los Alamos, New Mexico, United States Accidental criticality Harry Daghlian dropped a tungsten carbide brick onto a plutonium core, inadvertently creating a critical mass at the Los Alamos Omega site. He quickly removed the brick, but was fatally irradiated, and died on September 15. May 21, 1946 Los Alamos National Laboratory, Los Alamos, New Mexico, United States Accidental criticality
While demonstrating his technique to visiting scientists at Los Alamos, Canadian physicist Louis Slotin manually assembled a critical mass of plutonium. A momentary slip of a screwdriver caused a prompt critical reaction. Slotin died on May 30 from massive radiation poisoning, with an estimated dose of 1,000 rads (rad), or 10 grays (Gy). Seven observers, who received doses as high as 166 rads, survived, yet three died within a few decades from conditions believed to be radiation-related.
Slotin worked with the same bomb core as Daghlian which became known as the "demon core." It was later melted down and combined with existing weapons-grade material.
1950s