The chemical reactions involve change in electron number or arrangement of electrons in an atom or atoms in a molecule. This leads to changes in chemical properties and hence a reaction takes place. These changes are dependent upon: Temperature, Pressure , other reaction conditions, the amount etc.
However nuclear reactions involves changes even at nuclear level (protons and neutrons). These changes are independent of reaction conditions.
Thus we can say that the following statement is true
Chemical reaction rates vary with the conditions of the reaction, but nuclear decay rates do not.