Nuclear Disasters Disasters
The device briefly went supercritical when it was accidentally placed in supercritical configurations during two separate experiments intended to guarantee the core was indeed close to the critical point. The incidents happened at the Los Alamos Laboratory in 1945 and 1946, both resulting in the acute radiation poisoning and subsequent deaths of scientists: Harry Daghlian and Louis Slotin. After these incidents the spherical plutonium core was referred to as the "demon core".
The demon core (like the second core used in the bombing of Nagasaki) was a solid 6.2-kilogram (14 lb) sphere measuring 89 millimetres (3.5 in) in diameter. It consisted of three parts: two plutonium-gallium hemispheres and a ring, designed to keep neutron flux from "jetting" out of the joined surface between the hemispheres during implosion. The core of the device used in the Trinity nuclear test at the Alamogordo Bombing and Gunnery Range in July did not have such a ring.
The refined plutonium was shipped from the Hanford Site in Washington state to the Los Alamos Laboratory; an inventory document dated August 30 shows Los Alamos had expended "HS-1, 2, 3, 4; R-1" (the components of the Trinity and Nagasaki bombs) and had in its possession "HS-5, 6; R-2", finished and in the hands of quality control. Material for "HS-7, R-3" was in the Los Alamos metallurgy section, and would also be ready by September 5 (it is not certain whether this date allowed for the unmentioned "HS-8"'s fabrication to complete the fourth core). The metallurgists used a plutonium-gallium alloy, which stabilized the δ phase allotrope of plutonium so it could be hot pressed into the desired spherical shape. As plutonium was found to corrode readily, the sphere was then coated with nickel.
Marshall added an annotation, "It is not to be released on Japan without express authority from the President", as President Harry S. Truman was waiting to see the effects of the first two attacks. On August 13, the third bomb was scheduled. It was anticipated that it would be ready by August 16 to be dropped on August 19. This was pre-empted by Japan's surrender on August 15, 1945, while preparations were still being made for it to be couriered to Kirtland Field. The third core remained at Los Alamos. More details
The demon core was a spherical 6.2-kilogram (14 lb) subcritical mass of plutonium 89 millimetres (3.5 in) in diameter that was involved in two criticality accidents, on August 21, 1945 and May 21, 1946. The core was intended for use in a third nuclear weapon, but remained in use for testing after Japan's surrender. It was designed with a small safety margin to ensure a successful explosion of the bomb.
The demon core (like the second core used in the bombing of Nagasaki) was a solid 6.2-kilogram (14 lb) sphere measuring 89 millimetres (3.5 in) in diameter. It consisted of three parts: two plutonium-gallium hemispheres and a ring, designed to keep neutron flux from "jetting" out of the joined surface between the hemispheres during implosion. The core of the device used in the Trinity nuclear test at the Alamogordo Bombing and Gunnery Range in July did not have such a ring.
The refined plutonium was shipped from the Hanford Site in Washington state to the Los Alamos Laboratory; an inventory document dated August 30 shows Los Alamos had expended "HS-1, 2, 3, 4; R-1" (the components of the Trinity and Nagasaki bombs) and had in its possession "HS-5, 6; R-2", finished and in the hands of quality control. Material for "HS-7, R-3" was in the Los Alamos metallurgy section, and would also be ready by September 5 (it is not certain whether this date allowed for the unmentioned "HS-8"'s fabrication to complete the fourth core). The metallurgists used a plutonium-gallium alloy, which stabilized the δ phase allotrope of plutonium so it could be hot pressed into the desired spherical shape. As plutonium was found to corrode readily, the sphere was then coated with nickel.
