Naslov
NPP Krško Large Break Loss of Coolant Accident using MELCOR Code

Autori
Benčik, Vesna ; Grgić, Davor ; Šadek, Siniša

Vrsta, podvrsta i kategorija rada
Radovi u zbornicima skupova, cjeloviti rad (in extenso), znanstveni

Izvornik
NENE2021 Conference Proceedings / Cizelj, Leon ; Tekavčič, Matej - Ljubljana : Društvo jedrskih strokovnjakov Slovenije | Nuclear Society of Slovenia, 2021, 420-1

ISBN
978-961-6207-51-5

Skup
30th International Conference Nuclear Energy for New Europe (NENE 2021)

Mjesto i datum
Bled, Slovenija, 06.09.2021. - 09.09.2021

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
MELCOR, LOCA, DBA, guillotine break

Sažetak
NPP Krško (NEK) input deck for severe accident code MELCOR is being developed at Faculty of Electrical Engineering and Computing (FER) Zagreb. MELCOR is fully integrated computer code that models the progression of severe accidents in light water nuclear power plants. Recently, the MELCOR 1.8.6 input deck was converted to MELCOR 2.1 as well as to a new code version MELCOR 2.2. In this paper the results of Large Break Loss of Coolant Accident (LB LOCA) using MELCOR 1.8.6 as well as MELCOR 2.1 and MELCOR 2.2 are presented. Both unmitigated scenario (Engineered Safety Features (ESF) not available) and design basis (DB) scenario (one train of ESF available) have been analyzed. The postulated accident is initiated as a guillotine break in cold leg 1 (loop with pressurizer) discharging in Steam Generator (SG) 1 compartment. Simultaneously, an artificial valve connecting two previously connected volumes is closed. In the scenario with ESF available, one high head and one low head safety injection pump with maximum delay (30 seconds) were assumed available. The accumulator in the broken loop was assumed to spill into containment. Transient was simulated for 10000 seconds. Sensitivity analyses were performed for various values of break discharge coefficients (0.4, 0.6, 0.75 and 1.0) in order to find the most adverse scenario. The results for the analysis with ESF available were assessed against 10CFR50.46 criteria with relation to peak cladding temperature (1477 K) and hydrogen mass (1%). For all three MELCOR code versions the satisfactory behavior of ESF (1 ECCS train and 1 ESF train in containment), both in RCS and in the containment was demonstrated. For unmitigated scenario only short term results up to 10000 s including time of the Lower Head Failure (LHF) and mass of hydrogen in the core were determined.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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