Isomer Bombs

To understand what an isomer bomb is, you must first understand how nuclear power works. Isomers are atomic nuclei that have the same mass and atomic number but differ in their radioactivity. You could swiftly modify the state of these nuclear isomers if you designed an isomer bomb. They call it triggering because these nuclei ordinarily decay extremely slowly, but if you trigger them and it works, you will be able to receive a big burst of gamma and x-ray radiation. So it'd be stable enough until you needed it to explode up on demand. The energy burst that would result would be enormous.

At the moment, an isomer bomb, commonly associated with the nuclear isomer of hafnium, is thought to be at least 100,000 times more energetic than a chemical reaction. One gram of hafnium has the same energy as 660 pounds of TNT. Because the energy produced involves a shift of energy between nucleons, it is a distinct type of nuclear energy than fission or fusion. It's also purely theoretical right now.

The hafnium issue happened in the 1990s, and a group of researchers claimed to have actually been able to induce an isomer reaction. However, no other scientists were able to replicate the results, and many scientists believe it is impossible. Nonetheless, Russia appears to have continued research into the concept of an isomer bomb.