This is the twenty-fourth edition of Reference Data Series No. 2, which presents the most recent reactor data available to the IAEA. It contains summarized information as of the end of 2003 on: (1) power reactors operating or under construction, and shut down; and (2) performance data on reactors operating in the IAEA Member States, as reported to the IAEA. The information is collected by the Agency through designated national correspondents in the Member States. The replies are used to maintain the IAEA's Power Reactor Information System (PRIS).