And can it affect undead or constructs?
The question I more of had then is do things that block negative levels block the negative levels gained through handeling radioactive material? Or the explosion from sunmetal?Death ward protects against "death spells, magical death effects, energy drain, and any negative energy effects". Radiomantic bombs don't reference any of those, so no. As is, the only way to protect against it is to be inside of a lead input net, or in an antimagic field (and that last one won't help against a bomb made by a 20th level gramarist).