AbstractThe first JET tritium experiment [1] was performed with no radiological incidents, minimal radiation exposure to JET personnel and controlled aerial discharges of tritium to the environment well within daily release limits derived from the discharge Authorisation. Most of the radiological protection measures are fundamental design features of the machine and its buildings. These have been in place for many years as JET is intended for protracted tritium operations. They all performed well and confirmed not only their basic design but also minor areas where enhancements had been thought necessary. Special additional equipment was necessary to perform this limited experiment and they were all designed and operated to the same criteria of safety and radiological protection, taking into account the extent of the experimental programme. The range of radiological protection measures implemented and their performance are described in the paper.