AECB (Atomic Energy Control Board) personnel have reviewed in detail the main aspects related to the safe operation of the Gentilly-2 nuclear power plant during 1990. This station is operated by Hydro-Quebec under a licence issued by the AECB. This evaluation is based primarily on the contents of various reports submitted by Hydro-Quebec pursuant to the terms of the operating licence, as well as on the results of inspections, audits, and tours made by AECB personnel. In general, the station was operated safely. The submission of significant event reports is unacceptably delayed. An increasing number of contraventions of the operating licence has been noted during the last two years. A significant unavailability of the containment system has been attributed to high-activity detectors that did not meet design specifications. AECB personnel will take required action in 1991 in order to resolve the questions related to a pipe break in the turbine building.