The European Commission, DG XII, has published the fourth annual progress report on "The Community's research and development programme on decommissioning of nuclear installations (1989-1993)". The report summarizes the objectives, scope and work programme of the 79 research contracts concluded under the programme, as well as the progress achieved and the results obtained in 1993. In particular, the following topics are covered by the report: - R&D projects: . Long-term integrity of buildings and systems; . Decontamination for decommissioning purposes; . Dismantling techniques; . Treatment of specific waste materials; . Quantification and adaptation of remote-controlled semi-autonomous manipulator systems; . Estimation of the quantities of radioactive waste arising from decommissioning of nuclear installations in the Community; - Identification of guiding principles; - Testing of new techniques in practice.