2-PHASE FLOW PHENOMENA IN FULL-SCALE REACTOR GEOMETRY

For the investigation of two-phase flow phenomena in full scale reacto r geometry, a series of experiments were carried out at the Upper Plen um Test Facility UPTF, which represents the primary system of a 1300 M We Pressurized Water Reactor with upper plenum, downcomer and primary main coolant pipes in 1:1 reactor scale. UPTF was the German contribut ion to the international 2D/3D project established by the Japan Atomic Energy Research Institute (JAERI), the Nuclear Regulatory Commission (USNRC) of the United States of America, and the Federal Ministry for Research and Technology (BMFT) of the Federal Republic of Germany. Lar ge scale findings of the UPTF tests, related to two-phase flow phenome na in the downcomer, in the upper plenum, at the upper core tie plate, and in the main coolant pipes, will be discussed. The application of the UPTF test results for the validation of analytical models will be demonstrated.