Title: Weapon Materials Basics | Union of Concerned Scientists
Headings: Weapon Materials Basics
Weapon Materials Basics
Fissile materials basics
How much is needed to build a bomb?
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Content: HEU can be diluted with natural uranium to produce LEU, effectively eliminating the risk that it could be used to make a nuclear weapon if stolen by terrorists. However, as sophisticated enrichment technology spreads around the world, more groups will be able to overcome the technical barriers to producing HEU for weapons. For this reason, Pakistan's illicit transfer of advanced enrichment technology to Iran, Libya and North Korea is of grave concern to the international community. Moreover, the commercial enrichment facilities used to make LEU fuel for power reactors can be reconfigured to produce HEU for weapons. Without strong regulations in place, these dual-use facilities pose major risks of nuclear terrorism. In addition, the continued use of HEU for both civilian research and naval propulsion reactors increases the risk of terrorist access to this material. Plutonium. Plutonium occurs only in trace amounts in nature. It is produced as a matter of course in power reactors when the uranium-238 in reactor fuel absorbs neutrons. Countries producing plutonium for weapons have generally operated their reactors to maximize the production of plutonium-239—the isotope most useful for nuclear weapons—and to minimize the production of other plutonium isotopes such as plutonium-240.