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 $\ce{^99Tc}$?

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• I don't quite follow the question. kWh is a unit of energy. Are you asking what the total energy released if 1 kg of technetium-99m transitions to technetium-99 emitting mostly gamma rays? (I assume you mean Tc-99m because Tc-99 has an extremely long half-life, but correct me if I'm wrong) – Michael DM Dryden Jun 11 '15 at 18:12
• According to Nuclides 2000, the isotopic power of Tc-99 is only 8.6E−06 W/g; the value for Tc-99m is about 4.4E+03 W/g. – user7951 Jun 11 '15 at 18:15
• I'm trying to calculate the energy out put of TC 99 like 1 kg uranium 235 puts out 50,000 kWh – user46173 Jun 11 '15 at 18:16
• Can you clarify if you are talking about Tc-99 or Tc-99m. – bon Jun 11 '15 at 18:41

$\ce{^{99m}Tc}$ 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):
$$(142.6\ \mathrm{keV})(10.1\ \mathrm{mol})N_A = 8.673\times 10^{29}\ \mathrm{eV} = 139\ \mathrm{GJ} = 38.6\ \mathrm{MWh}$$
$$Q = (m_\mathrm{i}-m_\mathrm{f})c^2$$