Current containment blowdown experiments

The containment experiments with the HDR are made in order to measure transient load processes in simulated loss-of-coolant accidents in a typical full-pressure containment, and to use these measured data for verifying and improving existing computer programmes. First experiments of this kind have been started as integral tests on a containment mockup on a scale of 1:4 and 1:64, respectively, at the Battelle Institute for the purpose of confirming the conservativity of the computer programmes for the determination of the thermodynamic loads in the containment, and also in the case of loss-of-coolant accidents such as PREGA, ZOCO, CONDRU, COFLOW, DDIFF and COCO. Evaluating the experimental data and trying to apply these conservative results to real plants, one had to realize that the variety of parameters not sufficiently defined is too large to be determined by integral tests. The effects of the discharge coefficients of the flow conditions, of the heat transfer coefficients, the water entrainment, etc. have been stronger than expected in some cases and had to be eliminated from the evaluation in order to obtain transferrable experimental results. (orig./GL)