The European Commission, DG XI, has published an open invitation to tender for a study on the probabilistic safety assessment of steam generator tube rupture (SGTR) radiological releases. In 1992, the Commission's Reactor Safety Working Group launched a benchmark exercise aimed at the realistic assessment of radiological releases from SGTR faults. The results of this benchmark ("Realistic methods for calculating the release of radioactivity following steam generator tube rupture faults", EUR 15615 EN 1994) showed inter alia that some accident sequences, in certain plants within the design basis, could decrease the effectiveness of the fission product retention process, leading to higher radiological releases than initially expected. However, the probability of these sequences had not been quantified. The present study aims at the probabilistic assessment of these SGTR fault fission products releases and at identifying the risk dominant accidental sequences. The study will be performed as a benchmark exercise involving organizations from at least five different EU Member States. Each of these organizations will select a reference nuclear power plant design for which sufficient data have been collected in the framework of PSA level 1 studies and identify the abovementioned SGTR fault sequences which make the greatest contribution to risk dominant accidental sequences. An analysis/synthesis of the results will be done by another organization not taking part in the benchmark exercise with the aim of deriving information of the generic type, taking account of the differences in design, methodology and calculation assumptions. The study should be completed within 12 months following signature. Requests for the tender notice dossier should be submitted (quoting reference XI.C.2/960088) to: European Commission DG XI - Environment, nuclear safety and civil protection Mr. B. Sinnott Unit A.2 - Finances and contracts 200 rue de la Loi (TRMF 4/87) B-1049 Brussels Fax +32-2-2994449 Tenders should be submitted to the same address.