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 | | The Godiva device before and after an accidental excursion in February 1954 showing damage to the device. | A criticality accident (also sometimes referred to as an "excursion" or "power excursion") occurs when a nuclear chain reaction is accidentally allowed to occur in fissile material, such as enriched uranium or plutonium. This releases neutron radiation which is highly dangerous to surrounding personnel and which causes induced radioactivity in the surroundings. Wikipedia does not have an article with this exact name. ...
Wikipedia does not have an article with this exact name. ...
A nuclear chain reaction occurs when on average more than one nuclear reaction is caused by another nuclear reaction, thus leading to an exponential increase in the number of nuclear reactions. ...
This article or section should include material from Fissile material In nuclear engineering, a fissile material is one that is capable of sustaining a chain reaction of nuclear fission. ...
Enriched uranium is uranium whose uranium-235 content has been increased through the process of isotope separation. ...
General Name, Symbol, Number Plutonium, Pu, 94 Chemical series Actinides Period, Block 7, f Density, Hardness 19816 kg/m3, no data Appearance silvery white metal Atomic properties Atomic weight 244. ...
Neutron radiation consists of free neutrons. ...
Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ...
When such incidents occur outside reactor cores and test facilities where fission is intended to occur, they pose a high risk both of injury or death to surrounding workers and of release of radioactive material. While dangerous, the low densities involved in these accidents limit the chain reaction, preventing them from becoming a nuclear explosion. A 23 kiloton tower shot called BADGER, fired on April 18, 1953 at the Nevada Test Site, as part of the Operation Upshot-Knothole nuclear test. ...
Cause
 Image of a 60-inch cyclotron, circa 1939, showing external beam of accelerated ions (perhaps protons or deuterons) ionizing the surrounding air and causing a blue glow. Due to the very similar mechanism of production, the blue glow likely very closely resembles the "blue flash" seen by Harry Daghlian and other witnesses of criticality accidents. Criticality can be achieved by metallic uranium or plutonium, and also by compounds and liquid solutions of these elements. The isotopic mix, the shape of the material, the chemical composition of solutions, compounds, alloys and composite materials, and the surrounding materials all influence whether the material will go critical, that is will sustain a chain reaction. The calculations can be complex, so installations both civil and military that handle fissile materials employ specially trained criticality officers to monitor operations and prevent criticality accidents. 60-inch cyclotron, circa 1939, showing beam of accelerated ions (perhaps protons or deuterons) escaping the accelerator and ionizing the surrounding air causing a blue glow. ...
60-inch cyclotron, circa 1939, showing beam of accelerated ions (perhaps protons or deuterons) escaping the accelerator and ionizing the surrounding air causing a blue glow. ...
Isotopes are forms of a chemical element whose nuclei have the same atomic number, Z, but different atomic masses, A. The word isotope, meaning at the same place, comes from the fact that all isotopes of an element are located at the same place on the periodic table. ...
Description Most criticality accidents result in what is called a "blue flash," when surrounding air is ionized by an intense pulse of X-rays and gamma rays. Criticality accidents can be generally divided into one of two categories: process accidents, where controls are generally in place to prevent any criticality, and research reactor accidents, where criticality is purposely achieved in a nuclear reactor used for physical experimentation, but for one reason or another goes out of control. In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...
This article is about electromagnetic radiation. ...
Nuclear power station at Leibstadt, Switzerland. ...
Records Criticality accidents have occurred both in the context of nuclear weapons and nuclear reactors. The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ...
Nuclear power station at Leibstadt, Switzerland. ...
In 1945, Los Alamos scientist Harry K. Daghlian, Jr. accidentally irradiated himself while performing a critical mass experiment with two half-spheres of plutonium, disfiguring his hand and eventually dying of radiation poisoning a month later. 1945 was a common year starting on Monday (link will take you to calendar). ...
Los Alamos National Laboratory, aerial view from 1995. ...
Harry K. Daghlian, Jr. ...
Radiation poisoning, also called radiation sickness, is a form of damage to organic tissue due to excessive exposure to ionizing radiation. ...
Another scientist, Louis Slotin performed the same experiment nine months later and also had a similar fatal accident. A sketch used by doctors to determine the amount of radiation to which each person in the room had been exposed during the excursion. ...
On 15 October 1958, a criticality excursion in the heavy water RB reactor at the Boris Kidrič Institute of Nuclear Sciences in Vinca, Yugoslavia killed one and injured five. October 15 is the 288th day of the year (289th in Leap years). ...
1958 was a common year starting on Wednesday of the Gregorian calendar. ...
Vinca is Vinca, a botanical genus; see Periwinkle (plant). ...
Yugoslavia (Jugoslavija in all south Slavic languages) is a term used for three separate but successive political entities that existed during most of the 20th century on the Balkan Peninsula in Europe. ...
On 23 September 1983, an operator at the RA-2 research reactor in Constituyentes, Argentina received a fatal 3700 rad dose of radiation changing the fuel rod configuration while moderating water was in the reactor. One dead, two injured. September 23 is the 266th day of the year (267th in leap years). ...
1983 is a common year starting on Saturday of the Gregorian calendar. ...
In a very different incident in 1999 at a Japanese uranium reprocessing facility in Tokai, Ibaraki, workers put a mixture of uranyl nitrate solution into a precipitation tank which was not designed to dissolve this type of solution and caused an eventual critical mass to be formed, and resulted in the death of two workers from radiation poisoning. 1999 is a common year starting on Friday of the Common Era, and was designated the International Year of Older Persons by the United Nations. ...
Tōkai (東海村; -mura) is a village located in Naka District, Ibaraki, Japan. ...
Since 1945 there have been at least 21 deaths from criticality accidents; 7 in the United States, 10 in the Soviet Union, 2 in Japan, 1 in Argentina, and 1 in Yugoslavia. 9 have been due to process accidents, with the remaining from research reactor accidents. Yugoslavia (Jugoslavija in all south Slavic languages) is a term used for three separate but successive political entities that existed during most of the 20th century on the Balkan Peninsula in Europe. ...
See also Radiation poisoning, also called radiation sickness, is a form of damage to organic tissue due to excessive exposure to ionizing radiation. ...
San Francisco Critical Mass, 29th April, 2005. ...
Sketch of induced nuclear fission, a neutron (n) strikes a uranium nucleus which splits into similar products (F. P.), and releases more neutrons to continue the process, and energy in the form of gamma and other radiation. ...
Pathways from airborne radioactive contamination to man This is a list of notable accidents involving nuclear material. ...
External links - Press release on a report on criticality accidents from Los Alamos National Laboratory
- List of radiation accidents
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