The Tritium Laboratory at the Chalk River Laboratories has recently been provided with a complete upgrade of the original 1979 Safety Analysis Report (SAR) in order to obtain authorization to increase the tritium inventory from 0.74 to 37 PBq. In particular, the re-analysis was intended to provide assurance that existing operational philosophy and analysis methods were consistent with technical advances and current safety and licensing requirements. Supporting documentation, design description, operations manual and emergency procedures were revised and updated. A systematic SAR format, developed for other facilities on site, was utilized. This paper summarizes the safety analysis contents and key insights and improvements resulting from the upgrade program.