Far more dangerous than U-235 are the elemental products given off when nuclear fuel goes through fission—especially iodine, strontium, and cesium. “These are the things that uranium splits into when it’s working in a reactor or a bomb,” says Smith. “Those fission products are much more densely radioactive than uranium.”

Israel says it has hit access routes to Iran's main nuclear enrichment site a day after US attacks. The UN's nuclear watchdog says it must be allowed to assess the damage to Iran's nuclear programme.

Israel says it is determined to destroy Iran’s nuclear program because its archenemy’s furtive efforts to build an atomic weapon are a threat to its existence