A thermomechanical analysis for one of the valves in the NPP at different transient thermal stresses was performed.
One of the regulatory body methods to supervise nuclear safety of a nuclear power plant is a review of plant modifications and evaluation of their impact on plant operating experience. The Slovenian Nuclear Safety Administration (SNSA) licensed in April 2003 the use of leak-before-break (LBB) methodology in the Krško NPP for the primary loop including surge line and connecting pipelines with minimal diameter of 6 inch. The SNSA decision based also on fracture mechanics analyses that include direct pipe failure mechanisms such as water hammer, creep damage, erosion and corrosion, fatigue and environmental conditions over the entire life of the plant. The evaluation of the operating transients pointed out, that presumed loadings, used for the LBB analysis, did not incorporate all the fast thermal transients data. For that purpose the SNSA requested Faculty of Mechanical Engineering (FS) in Ljubljana to perform additional analyses. The results of the analysis shall confirm the validity of the LBB analysis.
FERJANČIČ, Matjaž, ŠTOK, Boris, HALILOVIČ, Miroslav, KOC, Pino, MOLE, Nikolaj, OTRIN, Zoran, KOTAR, Andrej. Fast thermal transients on valve. V: JENČIČ, Igor (ur.), LENOŠEK, Melita (ur.). International Conference Nuclear Energy for New Europe 2007, Portorož, Slovenia, September 10-13. Conference proceedings. Ljubljana: Nuclear Society of Slovenia, 2007, str. 908.1-908.8.