This report describes simulation techniques used in the training of personnel involved in accident management of nuclear power plants (NPPs). This concerns both the plant personnel and the persons involved in the management of off-site releases. The report pertains to light water reactors and pressurized heavy water reactors, but it can equally be applied to power reactors of other types. The report is intended for use by experts responsible for planning, developing, executing or supervising the training of personnel involved in the implementation of accident management programmes in NPPs.