That is the Russian version, nicknamed "Tsar Bomba" it was the most powerful nuclear weapon ever detonated. It comprised a 500kt fission warhead as a trigger with fusion upping the yield to 100MT. It was redesigned with a much, much smaller fission trigger, but the eventual yield when tested was still ~60MT. It was also the most efficient nuclear bomb ever create, with about 98% fusion.
There isn't space to carry 1 reload per tube on a torpedo boat, let alone 18 spare torpedoes.