Verification of engineered safety of nuclear power plants by means of integral experiments at the PKL test stand - experimental verification of emergency management and provisions

Examinations into design-basis exceeding events taken into account as a hypothetical case of failure of the engineered safety systems, as well the experimental verification of accident management provisions for mitigation of damage under these extreme conditions form a major part of the experiments performed at the PKL test stand. The usefulness of these experiments for all parties concerned is evident. Apart from yielding information on the performance of the systems tested, the insight drawn from the experiments is expected to contribute important results supporting the further development and validation of thermohydraulics computer codes, such as ATHLET or RELAP. A number of various test runs investigating bleed and feed have shown that heat removal can be initiated and is performed even at a very late stage (after uncovery of the upper core). Thus sophisticated engineering of functions to manage the primary-loop depressurization in order to avoid the hot steam path is not required. All in all, the experiments simulating the plant operation and behaviour at the PKL systems revealed that the provisions and control functions are feasible and efficient. (orig./DG)