I agree with MasterMind555 about having more radioactive elements, but instead of random elements that no one has heard of, you could do what AntB did and make uranium that decays and gives off some kind of radiation
tutut125, nice idea, but in real life, deutrium and tritium do not react with plutonium or uranium, however, as for reactions, hydrogen is highly flammable so reactions with lava, fire and plasma are possible. In nuclear fusion, the gasses must heated to high temperature (normally, the deutrium and tritium must be heated into a plasma form that releases x-rays [high-energy photons] for fusion to occur) and under higher pressure than that required for plutonium fission, the advantage is that the pressure and heat generated is much higer than that of fission (fusion power is calculated as E=MC squared x 0.01 [E= energy released; M= mass of substance; c squared= speed of light squared])
Well, on the Radioactive Side, we COULD have FUSION as we have Fission already. As simply as: H2 or HE + HEAT + Pressure = Huge energy as in heat and pressure + Gamma rays(Neut) + Coal. And so it rolls. On and on.