Fission grenade

Fission Grenades were powerful explosive devices.

These weapons were only hand-sized, but two of them produced an explosive yield in excess of 2000 megatons and, once activated, were impossible to defuse.

The Oracle was able to manufacture these weapons and make them appear identical to the Race Banks it was sworn to protect. When Jackson tracked the Race Banks down, the Oracle instead gave him two fission grenades. The Fourth Doctor was able to swap these with the real Race Banks, leading to the P7E planetoid being destroyed along with the Oracle. (DW: Underworld)