Plutonium-239 Tungsten Radiation Shielding

Plutonium-239 is a fissile isotope of plutonium with a half-life of 24,110 years, which is mainly used for the production of fissile material or other materials, or used for industrial-scale irradiation. Due to plutonium-239 can produce large amounts of pure plutonium-239 at a lower cost than the high enriched uranium -235, it is also widely used in nuclear weapons and nuclear power plants. Plutonium-239 is artificially produced by fast neutrons in reactor to bombard uranium - 238, a fissile plutonium-239 atom can produce 207.1 MeV energy. In the reactor, the uranium-235 atoms yield two or three neutrons which would be absorbed by uranium – 238 to produce plutonium-239 and other isotopes. In fact, the role of production reactor is to burn part of the uranium-235 in exchange for plutonium-239, and per burn of a uranium-235 atom will get eight plutonium-239 atoms. Plutonium-239 can also absorb neutrons and has the least critical mass in all commonly used nuclear fuel.

Plutonium-239 is toxic, and can emit α particle. α particle is mainly consist of two protons and two neutrons, which is equivalent to the kernel of helium 4 or helium 4 after ionization（i.e., He^{2 +}）. Generally the chemical element which is radioactive and has a larger atomic weight can emit α particle through α decay to convert into lighter elements, until the element is stable. Since the volume of α particle is larger and it has two positive charges, it can easily ionize other substances. Once the radioactive materials that can emit α particles (such as radiation fog) are inhaled or eating by human, α particle can damage organ cells directly. Although the penetrating power of α particle is weak, its strong ionization ability to cause harm to biological organism is no less than that of other radiation.

Plutonium-239 tungsten radiation shielding is used to shield the radiation produced by the radioactive isotope plutonium-239. Compared with the conventional shielding materials (such as lead), tungsten alloy shielding reflects good radiation shielding effect. Lead is early used in the shielding field, but a discovery shows that the radiation shielding performance of lead shielding is not high enough and it can also seriously pollute the environment. Under the condition of the same thickness, the radiation shielding capability of the tungsten shielding is twice as good as lead shielding.

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