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Plutonium-238 (238 Pu or Pu-238) is a radioactive isotope of plutonium that has a half-life of 87.7 years. Plutonium-238 is a very powerful alpha emitter ; as alpha particles are easily blocked, this makes the plutonium-238 isotope suitable for usage in radioisotope thermoelectric generators (RTGs) and radioisotope heater units .
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. It can then be separated from the uranium in a nuclear reprocessing plant. Weapons-grade plutonium is defined as being predominantly Pu-239, typically about 93% Pu-239. [21]
238 Pu has become the most widely used fuel for RTGs, in the form of plutonium(IV) oxide (PuO 2). [34] However, plutonium(IV) oxide containing a natural abundance of oxygen emits neutrons at the rate of roughly 2.3 × 10 3 n/sec/g of plutonium-238. This emission rate is relatively high compared to the neutron emission rate of plutonium-238 metal.
The "reactor-grade" plutonium produced by a regular LWR burnup cycle typically contains less than 60% Pu-239, with up to 30% parasitic Pu-240/Pu-242, and 10–15% fissile Pu-241. [124] It is unknown if a device using plutonium obtained from reprocessed civil nuclear waste can be detonated, however such a device could hypothetically fizzle and ...
Plutonium-238 has a half-life of 87.74 years [11] and emits alpha particles. Pure 238 Pu for radioisotope thermoelectric generators that power some spacecraft is produced by neutron capture on neptunium-237 but plutonium from spent nuclear fuel can contain as much as a few percent 238 Pu, originating from 237 Np, alpha decay of 242 Cm, or (n,2n ...
Reactor-grade plutonium. Reactor-grade plutonium (RGPu)[1][2] is the isotopic grade of plutonium that is found in spent nuclear fuel after the uranium-235 primary fuel that a nuclear power reactor uses has burnt up. The uranium-238 from which most of the plutonium isotopes derive by neutron capture is found along with the U-235 in the low ...
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. Plutonium is classified according to the percentage of the contaminant plutonium-240 that it contains: Supergrade 2–3%; Weapons grade 3–7%; Fuel grade ...
This plutonium is also mostly Pu-238, which makes it unsuitable for fission bomb building, due to the high heat and spontaneous neutrons emitted. The third track, a LFTR doesn't make much spare fuel. It produces at most 9% more fuel than it burns each year, and it's even easier to design a reactor that makes only 1% more fuel.