Modeling of spent fuel pool and fuel handling building during loss of cooling

Ovaj rad opisuje osnovne fenomene unutar bazena za istrošeno gorivo (SFP) elektrane PWR tipa, te prikazuje postupak modeliranja zgrade za istrošeno gorivo (FHB) i bazena za istrošeno gorivo NE Krško u programskom alatu GOTHIC. Cilj rada je testiranje odziva modela za slučaj gubitka hlađenja, ispitivanje uvjeta u bazenu i zgradi za istrošeno gorivo za različite snage gorivnih elemenata, kao i provjera prihvatljivosti uobičajenih pojednostavljenih pretpostavki korištenih u analizama tipa „time to boiling“ i „time to uncovery“. Za proračun su korištena dva modela; detaljniji model koji prikazuje samo bazen za istrošeno gorivo te jednostavniji model bazena smješten unutar zgrade za istrošeno gorivo. Također, analiziran je porast tlaka unutar FHB te mogućnost sniženja tlaka dodavanjem ventilacijskog otvora i otvaranjem rolo-vrata na ulazu u zgradu.In this thesis, basic phenomena within the spent fuel pool (SFP) at PWR nuclear power plant are described. The process of modeling of the fuel handling building (FHB) and the spent fuel pool (SFP) at Nuclear power plant Krško using GOTHIC program code is also shown. The purpose of the study is to test the model response during loss of cooling accident, to test the pool and FHB conditions for different fuel assemblies heat loading, as well as to check applicability of usual simplified assumptions used in „time to boiling“ and „time to uncovery“ analyses. Two models were used for the calculation; one being a more detailed model that shows only the spent fuel pool and the other being a simpler model of a pool located within the fuel handling building. Furthermore, the pressure increase within FHB has been analyzed and the possibility of reducing the pressure by adding a ventilation opening and by opening the roller shutter at the entrance to the building