GE and Hitachi want to use nuclear waste as a fuel

(PhysOrg.com) -- One of the world's biggest providers of nuclear reactors, GE Hitachi Nuclear Energy (a joint venture of General Electric and Hitachi), wants to reprocess nuclear waste for use as a fuel in advanced nuclear ...

New plutonium discovery lights way to clean up nuclear waste

Plutonium has long been part of many countries' nuclear energy strategies, but scientists are still unlocking the mysteries behind this complicated element and seeing how they can use heavier, nuclear elements to clean up ...

Unexpected oxidation state for molecular plutonium discovered

Researchers at Los Alamos National Laboratory in collaboration with the University of California - Irvine (UCI) have uncovered a significant new chemical attribute of plutonium, the identification and structural verification ...

Plutonium keeps its electrons close to home

Found in nuclear fuel and nuclear weapons, plutonium is an incredibly complex element that has far-ranging energy, security, and environmental effects. To understand plutonium, scientists at Pacific Northwest National Laboratory ...

ORNL achieves milestone with plutonium-238 sample

With the production of 50 grams of plutonium-238, researchers at the Department of Energy's Oak Ridge National Laboratory have restored a U.S. capability dormant for nearly 30 years and set the course to provide power for ...

Making fuel for exploring space

Since its 1977 launch, NASA's Voyager 1 spacecraft has travelled farther than any other piece of human technology. It is also the only human-made object to have entered interstellar space.

Neutrons find 'missing' magnetism of plutonium

Groundbreaking work at two Department of Energy national laboratories has confirmed plutonium's magnetism, which scientists have long theorized but have never been able to experimentally observe. The advances that enabled ...

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Plutonium

Plutonium (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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