It is estimated that between one-half to two-thirds of the value of all U.S. currency in circulation is outside of the U.S. In 1934, the $100,000 Gold Certificate became the highest denomination ever issued. It was never intended for public use. Instead, it was meant solely for official transactions between Federal Reserve Banks.
Enriched uranium. Enriched uranium is a type of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight. 235U is the only nuclide existing in nature that is fissile with thermal neutrons.
The atomic number of uranium is 92, meaning that it has 92 protons and occupies place number 92 in the periodic table. It occurs naturally in six isotopes, U-233 to U-238 and therefore contains between 141 and 146 neutrons. The most common isotope is U-238 with a relative abundance of 99.3%.