A model is presented for calculating depressurization time for and particulate release from used nuclear fuel dry storage containers that have developed a pinhole breach. Particular attention is given to particulate deposition and transmission within the breach pathway. The model is modular in nature and is developed in a way that allows for more advanced treatments of internal temperature, internal component geometry, or aerosol flow to be readily incorporated. The model can be treated as a basis for addressing concerns associated with monitoring and verification efforts during long-term dry cask storage.