Pelletized pyrotechnic discs ("heat pellet") are used in thermally activated ("thermal") batteries for nuclear weapons for the Department of Energy (DOE) as well as in a large variety of missiles for the Department of Defense. Thermal batteries provide the primary power for these applications and depend on a molten-salt electrolyte. The batteries deliver power upon melting of the electrolyte caused by the heat released during burning of heat pellets in the battery stack. Prior to the use of

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... pellets, a heat paper based on Zr/BaCrO 4 was used as the heat source in thermal batteries. This material had a number of disadvantages, including static and shock sensitivity and forming highly resistive reaction products that would not allow for intercell connection of cells in a stack. This report describes the history of the development of pelletized pyrotechnics at Sandia National Laboratories for the DOE's nuclear weapons. The final chemistry selected was Fe/KClO 4 , since it met all of the desired qualities for the anticipated applications. This report also provides relevant historical aging data for this material, as well as related data generated as part of a stockpile surveillance program.