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As a part of its modernization plan, NPP Krsko (NEK) has obtained the Krško Full-Scope Simulator (KFSS). Simulators of this type are used for training and maintaining competence to ensure the safe and reliable operation of nuclearpower plants throughout the world. In this study the response of the modernized Krško nuclear power plant (NPP) to a total-loss-of-feedwater accident, leading to the total loss of the secondary heat sink, was calculated. Based on these results, the validation of the full-scope simulator was performed. The verified plant-specific RELAP5/MOD2 input model of the Krško NPP, adapted for the 2000 MWt power (cycle 17), including the model for replacement steam generators, was used. Core heatup occurred in the analyzed case. Core degradation and melting are outside the scope of the RELAP5/MOD2 best-estimate code simulation, but it can predict all the events up to the moment when the core cladding temperature starts to approach the melting point. The comparison of the Krsko full-scope simulator (KFSS) data with the calculated reference data shows good agreement and indicates that the simulator-validation testing for this kind of accident was successful. JE Krsko je v okviru načrta posodobitve v letu 2000 pridobila tudi popolni simulator. Ta je namenjen usposabljanju in vzdrzevanju zmoznosti osebja, da zagotavlja varno in zanesljivo obratovanje. V tej studiji smo izračunali odziv posodobljene jedrske elektrarne Krsko na nezgodo s popolno izgubo napajanja uparjalnikov, ki vodi do popolne izgube ponora toplote na sekundarni strani. Izračun je bil potreben za preveritev popolnega simulatorja,ki so ga v JE Krsko pridobili v okviru načrta posodobitve v letu 2000. Uporabljen je bil ze preverjeni vhodni model za program RELAP5žMOD2 za jedrsko elektrarno Krsko (JEK), vendar prirejen za 2000 MW toplotne moei (17. gorivni krog) in nova zamenjana uparjalnika. V obravnavani nezgodi se sredica osuši in pregreje, kar vodi v taljenje sredice. Čeprav program RELAP5/MOD2 za opis takih pojavov ni predviden, kljub temu lahko z njim napovemo vse dogodke do tedaj, ko se zaene temperatura gorivnih srajčk priblizevati talisču. Primerjava podatkov, dobljenih s popolnim simulatorjem JE Krsko, in izračunanih primerjalnih podatkov kaze dobro ujemanje in potrjuje, da je bila preveritev simulatorja za to vrsto nezgode uspesna. |
