Effectiveness of emergency procedures under BDBA-conditions -- Experimental investigations in an integral test facility (PKL)

As part of the German reactor safety program, experimental investigations into the thermal hydraulic behavior of pressurized water reactors (PWRs) under accident conditions have been performed in the PKL test facility by Siemens/KWU. PKL is a mockup of a typical 4-loop 1,300 MWe KWU-PWR, based on a volumetric scale of 1:145 and full-scale component heights. The topic of beyond-design-basis accidents (BDBAs), such as total loss of feedwater, including experimental verification of relevant accident management procedures, was the main subject of interest in the test program PKL III C, which was completed in June 1995. The test results demonstrated that even under extreme boundary conditions, core damage can be prevented by performing accident management procedures. Especially the high efficiency of the secondary side bleed-and-feed, which is the preferred measure according to the accident management concept of German PWR plants, was clearly shown. This paper summarizes the fundamental findings of the PKL III C program, focusing on experimental results concerning the efficiency of secondary side bleed-and-feed procedures during loss of feedwater transients. For completeness additional results regarding this topic from the preceding program 3 B and the first results from the current program III D will be included