This cannon won't fire....

[mmartin798]

The closest I have ever come to rationalizing the blue undead is to say it is a fungus that thrives on radiation that had taken over the brain and body functions of a live or recently dead host. There exists in nature fungus that live on radiation and fungus that take over the bodies of insects. Combine the two and you require a lot less handwavium to make the blue undead. But yeah, I don't use them either.