Nuclide Energy and Isomer Depletion

Nuclide energy is a subset of nuclear energy that utilizes induced radioactive decay to generate considerable amounts of alpha or beta particles. We identified possible depletion paths to transform a nuclide from an energy-storing isomeric state to an energy-releasing ground state for potential Army energy and power applications. While isomers decay naturally, we can bypass their slow decay with the bombardment of an external energy source. The nucleus can “switch” to the shorter-lived ground state by exciting out of the isomer into a depletion level where it is able to subsequently decay to the ground state following a depletion pathway, a sequence of electromagnetic transitions. This process of depletion has potential use in energy applications as a nuclear battery. We have sought the potential paths from the National Nuclear Data Center’s ENSDF. While the ENSDF has information on over 3,100 nuclides, we explored 12 nuclides known to have an isomeric half-life greater than one year. Of the nuclides in question, we have identified complete depletion paths in ¹⁰⁸Ag, ¹²¹Sn, and ¹⁶⁶Ho. To characterize depletion of the isomers, we calculated an energy-integrated cross section (ICS) for each pathway. The ICS values provide a benchmark for the probability of a depletion occurring via a certain path. After analysis of the depletion pathways, we determined that ¹⁰⁸Ag has the highest ICS and is, therefore, a strong candidate for energy applications.