The Monitored Geologic Repository (MGR) Waste Package Operations of the Civilian Radioactive Waste Management System Management & Operating (CRWMS M&O) contractor performed calculations to provide input to the design of a waste package (WP). This document analyzes the degradation processes of two types of pressurized water reactor (PWR) spent nuclear fuel (SNF): • Fuel fabricated from low enriched uranium oxide, which has been used, or will ~ used, in commercial nuclear power plants.