Plutonium
hidePlutonium (pronounced /pluːˈtoʊniəm/, symbol Pu, atomic number—or element—94) is a rare transuranic radioactive element. It is an actinide metal of silvery-white appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen and silicon. When exposed to moist air, it forms oxides and hydrides that expand the sample up to 70% in volume, which in turn flake off as a powder that can spontaneously ignite. It is also a radioactive poison that accumulates in bone marrow. These and other properties make the handling of plutonium dangerous, although its overall toxicity is sometimes overstated.
The most important isotope of plutonium is plutonium-239, with a half-life of 24,100 years. Plutonium-239 is fissile, meaning that the nuclei of its atoms can break apart by being bombarded by slow moving neutrons, releasing energy, gamma radiation and more neutrons. It can therefore sustain a nuclear chain reaction after reaching a critical mass, leading to applications in nuclear weapons and use in some nuclear reactors. The most stable isotope of plutonium is plutonium-244, with a half-life of about 80 million years, long enough to be found in trace quantities in nature. Plutonium-238 has a half-life of 88 years and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, which are used to power some spacecraft. Plutonium-240 has a high rate of spontaneous fission, raising the background neutron rate of any sample it is contained in. The presence of Pu-240 ends up limiting a sample's weapon and power potential and determining its grade: weapons (< 7%), fuel (7–19%) and reactor grade (> 19%). Pu-238 and Pu-239 are synthesized by bombarding uranium-238 with deuterons and neutrons, respectively.
Element 94 was first synthesized in 1940 by a team led by Glenn T. Seaborg and Edwin McMillan at a University of California, Berkeley laboratory. McMillan named the new element after Pluto, and Seaborg suggested the symbol Pu as a joke. Trace amounts of plutonium were subsequently discovered in nature. Discovery of plutonium became a classified part of the Manhattan Project to develop an atomic bomb during World War II. The first nuclear test, "Trinity" (July 1945), and the second atomic bomb used to destroy a city (Nagasaki, Japan, in August 1945), "Fat Man", both had cores of Pu-239. Human radiation experiments studying plutonium were conducted without informed consent, and a number of criticality accidents, some lethal, occurred during and after the war. Disposal of plutonium waste from nuclear power plants and dismantled nuclear weapons built during the Cold War is a major nuclear-proliferation, health, and environmental concern. Other sources of plutonium in the environment are fallout from numerous above-ground nuclear tests (now banned) and several nuclear accidents.
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News tagged with plutonium
Fuel for deep space exploration running on empty
Space & Earth / Space Exploration
May 07, 2009 |
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(AP) -- NASA is running out of nuclear fuel needed for its deep space exploration.
Engineers develop technique to help combat nuclear proliferation
Mar 04, 2009 |
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Ben-Gurion University of the Negev engineers have developed a technique to "denature" plutonium created in large nuclear reactors, making it unsuitable for use in nuclear arms. By adding Americium (Am 241), a form of the ...
Scientists discover historic sample of bomb-grade plutonium
Chemistry / Analytical Chemistry
Feb 26, 2009 |
4.3 / 5 (6) |
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(PhysOrg.com) -- Scientists in Washington state are reporting the surprise discovery of the oldest known sample of reactor-produced bomb-grade plutonium, a historic relic from the infancy of America’s nuclear weapons program. ...
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Scientists discover how nanocluster contaminants increase risk of spreading
Nanotechnology / Bio & Medicine
Apr 17, 2008 |
4 / 5 (1) |
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For almost half a century, scientists have struggled with plutonium contamination spreading further in groundwater than expected, increasing the risk of sickness in humans and animals.
U.S. says it will discard some plutonium
Sep 18, 2007 |
3.2 / 5 (5) |
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The U.S. Department of Energy announced it will remove 9 metric tons of plutonium from further use as fissile material in nuclear weapons.
Japan's plutonium stockpile tops 43 tons
Sep 08, 2005 |
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The Japanese government says its stockpile of plutonium had grown to 43.1 tons as of the end of 2004, up 2.4 tons from 2003.
Scientists resolve 60-year-old plutonium questions
Jun 06, 2006 |
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Scientists have solved a question about the nature of plutonium that had remained a mystery since the Manhattan Project.
Low-Level Plutonium Sample Involved in NIST-Boulder Lab Incident
Jun 11, 2008 |
3.7 / 5 (7) |
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On Monday afternoon, June 9, researchers in a laboratory room at the Commerce Department's National Institute of Standards and Technology (NIST) campus in Boulder, Colorado discovered that a vial holding about 1/4 of a gram ...
Workers exposed to plutonium at Los Alamos
Dec 23, 2005 |
5 / 5 (5) |
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Five workers at New Mexico's Los Alamos National Laboratory are being monitored after an accident resulted in plutonium being found inside their noses.
Scientists unlock physical, chemical secrets of plutonium
Mar 28, 2007 |
4.4 / 5 (33) |
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Researchers at Rutgers, The State University of New Jersey, have unlocked some of the physical and chemical secrets of plutonium, an element known for its use in atomic weapons and power plant fuel. While the complex nuclear ...
Concerned Scientists criticize nuke plant
Aug 01, 2007 |
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The Union of Concerned Scientists is upset over U.S. plans to build a plutonium processing plant without consulting the International Atomic Energy Agency.
Rocky Flats radiation to be reviewed
Apr 24, 2006 |
4.3 / 5 (4) |
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A National Institute for Occupational Safety and Health advisory panel begins a three-day meeting in Denver Tuesday, focusing on the Rocky Flats.
Researchers track Chernobyl fallout
Space & Earth / Earth Sciences
Oct 01, 2008 |
3.8 / 5 (5) |
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When a reactor in the Chernobyl nuclear power plant exploded in 1986 in what was then the Soviet republic of Ukraine, radioactive elements were released in the air and dispersed over the Soviet Union, Europe and even eastern ...
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