The NOKO/TOPFLOW facility for natural convection flow

For the study of the effectiveness of passive safety systems a high pressure (up to 7 MPa) and high power (up to 4 MW) test facility - named NOKO - has been constructed and operated at the Forschungszentrum Juelich. From 1996-1998 this facility was used for a project within the 4th FP of the EU 'European BWR R and D Cluster for Innovative Passive Safety Systems'. An overview and selected results are given for the tests with two bundles of the emergency condenser, with the building and plate condenser, with 4 different passive initiators, with a passive flooding system and with decay heat removal tests during shutdown. It has been decided to decrease substantially the safety research at the Forschungszentrum Juelich; to maintain the experimental competence for two-phase flow the NOKO facility will be transferred to the Forschungszentrum Rossendorf by the end of the year 2000 up to the beginning of the year 2001. The facility will be named TOPFLOW; the main objectives of future tests will be oriented towards more generic research: investigation of steady state and transient two-phase flow phenomena especially transient two-phase flow patterns, the development of two-phase flow instrumentation, the generation of a data basis for Computational Fluid Dynamic (CFD)-Code validation and testing of heat exchangers and safety systems. An overview will be given about the modifications and improvements related to the test facility and the planned tests. (author)