I think we should add a radioactive solid called radium. It will be a bright yellowy-green and slowly decay into uranium and stone at a 1:2 ratio. It will melt into liquid radium (LRDM) at 1,200 degree's and vaporise into radium gas (RDMG) at 1,900 degrees.
Radium liquid and gas will pouduce molten uranium and lava instead, Plotonium will be poduced instead of uranium in contact with salt water, Radium will poduce heat regardless of pressure.
It could be used in reactors, bombs and as radioactive fallout.
make it have some really wild properties, like RADM would color surrounding water a light greeny-glowie color, to simulate raidioactivity in the water, to please the irradiated water people. or perhaps when hit by electrons, it would expel photons or something like that. remember, there are people out there who arent fans of realism, so keep that in mind!
EDIT:
what about if it creates pressure in the presence of another element, say brmt?
(brmt because you could turn it on and off)
That adds some good uses.
Perhaps if the radium was in distilled water, it would produce a blue glow, while in other types of water it would have the greenish glow.
Also, radioactive fallout is mentioned as a use, but what reaction should produce it?