Major findings of PMK-2 Test Results and Validation of Thermohydraulic System Codes for VVER Safety Studies [antikvár]

PREFACEThe PMK-2 facility is located at the MTA KFKI Atomic Energy Research Institute, Budapest, Hungary. It is a full-pressure thermohydraulic model of the primary and partly the secondary circuit ofVVER-440/V-213 type units of Paks NPP. At the start-up time of Paks NPP, PMK-2 was the first and only integral-type facility for WERs. PMK-2 was later followed by the PACTEL facility for VVER-440 (Finland, 1990) and by the ISB and PSB facilities for VVER-1000 (Russia, 1992 and 1998, resp.).The integral type facilities have great safety significance since they can provide experimental information on transients and accidents anticipated to occur in power plants, while similar experiments can not be performed in the plants themselves because of the unacceptably high risk. In case of Paks NPP, the vendor provided the safety analysis without giving any details on the experimental validation of the computer codes applied in the DBA analyses. In order to cope with this deficiency, the PMK-2 facility was built and the experimental projects were initiated. Though the results of these experiments did not lead to surprising results if one considers the calculational results of system codes developed for PWR modelling, the need to have reliable experiments on WER-440/V-213 system behaviour is obvious. Paks NPP faced with a similar situation in the 1990s. This was the time when the Symptom Oriented Accident Management had to be introduced in order to enhance the operational safety of the plant. PMK-2 again contributed very significantly to this project by allowing to study of various phenomena during risky situations and to determine the parameters of the procedures.Though PMK-2 was constructed and utilised basically for national interests, the results have always been shared with the international nuclear community. A wide interest was experienced not only from the countries having VVER reactors, but also from the experts of other countries who wanted to understand better the WER specific phenomena.A large number of integral-type tests have been performed in the past 30 years all over the world in different test facilities. OECD CSNI recognised that there is a tremendous danger of loosing these test results due to the closing down many of these facilities, retirement of experts and changes in data storage. A huge effort was initiated in the 1990s to collect the most important data included in the CSNI Integral Test Facility Validation Matrix at the NEA Data Bank. The Final Report on PMK-2 Projects is a contribution to this effort.Since the start-up of the PMK-2 facility in 1985, altogether 55 experiments have been performed primarily in international frameworks with the participation of several experts from European and overseas countries to study one- and two-phase natural circulation, loss of coolant accidents, special plant transients and accident management9