The purpose of a Prestartup / Operational Readiness Review (PSR) is to ensure that initial start-ups, or start-ups following major project work, proceed safely and smoothly. In particular, the PSR will check to make sure that all project activities are complete and that the system is ready for safe operation. It is a tool that the operations and maintenance departments use to make ensure that they have received what they expected to receive from the project team, and that no corners were cut, particularly with regard to safety.