kWh of radioactive elements database?

I recently been studying different radioactive elements. The most difficult part is find the output of these elements in the form of kWh.


Is there a database or chart of these elements' output? 


And most importantly does anyone know the kWh of $1~ kg$ of $\ce{^99Tc}$? 




$\ce{^{99m}Tc}$ is a nuclear isomer of $\ce{^{99}Tc}$, which is excited by 142.6 keV. Therefore, when one atom decays to $\ce{^{99}Tc}$, it releases 142.6 keV, mostly as gamma radiation, but also some internal conversion occurs. Therefore, for 1 kg of $\ce{^{99m}Tc}$ (10.1 mol):


$$
(142.6\ \mathrm{keV})(10.1\ \mathrm{mol})N\_A = 8.673\times 10^{29}\ \mathrm{eV} = 139\ \mathrm{GJ} = 38.6\ \mathrm{MWh}
$$


In general, the total energy released by a nuclear reaction in a given mass is simply the decay energy (commonly known as the Q value) multiplied by the number of atoms. The Q value is simply the difference in mass between the starting material and final product converted to energy:


$$Q = (m\_\mathrm{i}-m\_\mathrm{f})c^2$$


Q values are easy to just look up, though. ([Wolfram|Alpha](http://www.wolframalpha.com/input/?i=technetium-99) is a good place)


Of course, depending on the application, all this energy is not accessible or useful. If one were trying to make an [RTG](http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator), an enormous amount of shielding would be needed to turn the gamma rays into heat, since they penetrate matter very well, where things like Pu-238 work better because they release mostly alpha particles, which are easily absorbed, delivering their kinetic energy as heat.


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