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Moreover, 239 Pu and 240 Pu cannot be chemically distinguished, so expensive and difficult isotope separation would be necessary to separate them. Weapons-grade plutonium is defined as containing no more than 7% 240 Pu; this is achieved by only exposing 238 U to neutron sources for short periods of time to minimize the 240 Pu produced.
Pu-239 is produced artificially in nuclear reactors when a neutron is absorbed by U-238, forming U-239, which then decays in a rapid two-step process into Pu-239. [22] It can then be separated from the uranium in a nuclear reprocessing plant. [23] Weapons-grade plutonium is defined as being predominantly Pu-239, typically about 93% Pu-239. [24]
The most stable are 244 Pu with a half-life of 80.8 million years; 242 Pu with a half-life of 373,300 years; and 239 Pu with a half-life of 24,110 years; and 240 Pu with a half-life of 6,560 years. This element also has eight meta states ; all have half-lives of less than one second.
The first production reactor that made 239 Pu was the X-10 Graphite Reactor. It went online in 1943 and was built at a facility in Oak Ridge that later became the Oak Ridge National Laboratory. [42] [note 5] In January 1944, workers laid the foundations for the first chemical separation building, T Plant located in 200-West.
The odd numbered fissile plutonium isotopes present in spent nuclear fuel, such as Pu-239, decrease significantly as a percentage of the total composition of all plutonium isotopes (which was 1.11% in the first example above) as higher and higher burnups take place, while the even numbered non-fissile plutonium isotopes (e.g. Pu-238, Pu-240 and ...
For instance, the use of MOX fuel (239 Pu in a 238 U matrix) is likely to lead to the production of more 241 Am and heavier nuclides than a uranium/thorium based fuel (233 U in a 232 Th matrix). For highly enriched fuels used in marine reactors and research reactors , the isotope inventory will vary based on in-core fuel management and reactor ...
It used pellets made of thorium dioxide and uranium-233 oxide; initially, the U-233 content of the pellets was 5–6% in the seed region, 1.5–3% in the blanket region, and none in the reflector region. It operated at 236 MWt, generating 60 MWe, and ultimately produced over 2.1 billion kilowatt hours of electricity.
Sierra Pacific Industries (SPI) is the second-largest lumber producer in the United States. [1] A privately held company, it was co-founded in 1949 by R. H. Emmerson and his son, A. A. "Red" Emmerson, the long-term CEO, and A. A. Emmerson's sons George and Mark are now president and CEO.