A Nuclear Weapons Primer

Abstract

Nuclear weapons deliver tremendous destructive energy in three primary forms: blast, heat, and radiation. Blast yields are measured by their equivalency to TNT. The atomic bomb used against Nagasaki in 1945 had a yield of approximately 21,000 tons (21 kilotons) of TNT. Within a one-mile range, the blast leveled or greatly damaged all buildings save those with reinforced concrete frames. The blast of a 300-kiloton bomb detonated above the Pentagon would destroy almost every building within 1.3 miles. And these are “small” bombs, so to speak. Hydrogen (also known as fusion or thermonuclear) bombs are so powerful their yields are measured in megatons. The first hydrogen device tested by the United States in November 1952 was equal to 10.4 million tons of TNT; its blast vaporized an entire island. Nuclear blasts are instantly followed by ferocious heat, which takes the form of a rapidly expanding fireball. The diameter of a 300-kiloton bomb’s fireball would reach more than a mile and obtain a peak temperature of more than 200 million degrees Fahrenheit. The fireball would engulf a city in flames, which the blast would feed by scattering ignited debris and by breaking gas lines. The 15-kiloton atomic bomb used against Hiroshima generated fires over a 4.4 square mile area; a 300-kiloton detonation above the Pentagon would likely start fires within an area measuring as much as 65 square miles.¹