Modeling of NPP Krsko Control and Protection System and Safety Systems Using TRACE Code

U ovom radu opisano je termo-hidrauličko modeliranje AFW i ECCS sustava, te zaštitnih i regulacijskih sustava Nuklearne elektrane Krško TRACE kodom pomoću SNAP pred-procesora i AptPlot post-procesora. Slikovito je opisano korištenje ovih alata, te su dani detaljni opisi problema na koje se naišlo prilikom modeliranja, kao i rješenja koja su implementirana. Objašnjeni su dijelovi RELAP5 koda na temelju kojeg je ova nodalizacija nastala. Pokazano je modeliranje hidrauličkih komponenti i rubnih uvjeta, a posebno je detaljno opisana funkcionalnost kontrolnih blokova te regulacijskih i logičkih sklopova NEK. Valjanost nodalizacije pokušala se potvrditi simuliranjem male LOCA-a i usporedbom odziva s rezultatima već verificirane RELAP-ove nodalizacije. Proračun stacionarnog stanja cijele elektrane programom TRACE je proveden ali rezultati pokazuju prevelika odstupanja i nisu prikazani u radu. Napravljen je proračun akcidenta mala LOCA programom RELAP5 kao priprema za kasniju tranzijentnu verifikaciju programa TRACE.This masters' thesis deals itself with thermo-hydraulic modelling of AFW and ECCS systems, as well as modelling of protection and regulation systems found in NPP Krško using TRACE code, with the help of SNAP as the preprocessing tool and AptPlot as the postprocessing tool. Detailed descriptions of the modeling process and the solutions implemented are given, complemented with a great number of illustrative images and RELAP code in which the original nodalization is written in. Fundamental modelling practices regarding hydraulic components and mora advanced practices regarding control components have been demonstrated. Validity of the nodalization itself was put to test by comparing it to the results of a small LOCA accident provided by the original, verified, RELAP nodalization. The steady state calculation of whole plant model was performed, but obtained results show large differences compared to reference results and are not shown in the thesis. Small break LOCA transient was calculated for NPP Krsko using RELAP5 code to prepare the data needed for ontransient verification of TRACE code