|
Plutonium-239 is an isotope of plutonium. Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 has also been used. Plutonium-239 is also one of the three main isotopes demonstrated usable as fuel in thermal spectrum nuclear reactors, along with uranium-235 and uranium-233. Plutonium-239 has a half-life of 24,110 years.〔(【引用サイトリンク】title=Physical, Nuclear, and Chemical Properties of Plutonium )〕 ==Nuclear properties== The nuclear properties of plutonium-239, as well as the ability to produce large amounts of nearly pure Pu-239 more cheaply than highly enriched weapons-grade uranium-235, led to its use in nuclear weapons and nuclear power stations. The fissioning of an atom of uranium-235 in the reactor of a nuclear power plant produces two to three neutrons, and these neutrons can be absorbed by uranium-238 to produce plutonium-239 and other isotopes. Plutonium-239 can also absorb neutrons and fission along with the uranium-235 in a reactor. Of all the common nuclear fuels, Pu-239 has the smallest critical mass. A spherical untamped critical mass is about 11 kg (24.2 lbs),〔(FAS Nuclear Wepons Design FAQ ), Accessed 2010-9-2〕 10.2 cm (4") in diameter. Using appropriate triggers, neutron reflectors, implosion geometry and tampers, this critical mass can be reduced by more than twofold. This optimization usually requires a large nuclear development organization supported by a sovereign nation. The fission of one atom of Pu-239 generates 207.1 MeV = 3.318 × 10−11 J, i.e. 19.98 TJ/mol = 83.61 TJ/kg.〔(【引用サイトリンク】title=Table of Physical and Chemical Constants, Sec 4.7.1: Nuclear Fission )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Plutonium-239」の詳細全文を読む スポンサード リンク
|