How do nuclear weapons explode?

Answer 1

fission or fusion? oh well lets do both...

fission:

1. electronic fusing system sends timed electrical pulses to detonators
2. detonators trigger conventional explosive lenses
3. explosive lenses focus detonation wave into spherical implosion wave
4. spherical implosion wave hits depleted uranium tamper compressing it
5. spherical implosion wave hits fissile core compressing it
6. when fissile core reaches optimal supercritical state, electronic fusing system sends timed electrical pulse to accelerator fusion neutron generator to spray core with neutrons starting fission
7. within 1 microsecond fission completes, core and tamper have vaporized
8. inertia of the tamper vapor holds back the core vapor for a couple more microseconds, building up pressure
9. the bomb explodes

fusion:

1. fission bomb trigger explodes
2. x-rays from fission bomb are channeled around fusion stage
3. x-rays ablate depleted uranium tamper of fusion stage compressing fusion stage
4. compression of fusion stage compresses plutonium "sparkplug" rod down center of fusion stage
5. neutrons from fission bomb trigger initiate fission in "sparkplug"
6. neutrons from "sparkplug" convert lithium in lithium deutride to tritium
7. deuterium-tritium mixture is compressed and heated between imploding depleted uranium tamper and exploding plutonium "sparkplug" until fusion burn begins
8. high energy fusion neutrons trigger fission of depleted uranium tamper (providing about 90% of yield and most of fallout)
9. the bomb explodes

You can add as many fusion stages as you need to get the yield you want.

Richard Rhodes: "The Making of the Atomic Bomb" & "Dark Sun"

Answer 2

Nuclear weapons explode through a process called nuclear fission or fusion. In nuclear fission, atoms are split apart, releasing large amounts of energy. In fusion, atoms are combined, producing even more energy. This energy release creates an explosive force.