To understand the Uranium Element, and Uranium 235 are not the same thing.
As a chemical element, Uranium belongs to the actinide series in the periodic table, with the chemical symbol U and atomic number 92. Due to its weak radioactivity, all its isotopes are unstable, causing it to exist naturally in three forms: Uranium 238, Uranium 235, and Uranium 234.
Among these three forms, only Uranium 235 can undergo spontaneous fission, in other words, only Uranium 235 can truly become the raw material for nuclear weapons.
And what is the content of Uranium 235?
Compared to Uranium 238's 99.2739% to 99.2752%, the content of Uranium 235 is only about 0.7198% to 0.7202%.
In other words, less than 0.1%, less than one-thousandth.
This is also the most challenging aspect of nuclear weapon research and manufacturing plans — how to separate Uranium 235 from Uranium 238 and extract it specifically?
