Analysis of Steam Generator Tube Rupture (SGTR) Accident for NPP Krško (CROSBI ID 594531)
Prilog sa skupa u zborniku | izvorni znanstveni rad | međunarodna recenzija
Podaci o odgovornosti
Benčik, Vesna ; Grgić, Davor ; Čavlina, Nikola
engleski
Analysis of Steam Generator Tube Rupture (SGTR) Accident for NPP Krško
Steam Generator Tube Rupture (SGTR) event leads to contamination of the secondary side due to leakage of the radioactive coolant from the Reactor Coolant System (RCS) through the broken Steam Generator (SG) tube(s). The major concern for the SGTR event is the release of contaminated liquid through the secondary side relief valves to the atmosphere that may result in an increase of radiological doses. The primary-to-secondary leakage results in the RCS depressurization, which leads to an automatic reactor trip (on low pressurizer pressure or overtemperature ΔT) and Safety Injection (SI) actuation. Since the RCS pressure tends to stabilize at the value where the incoming SI flow rate equals the break flow rate the operator must terminate the SI flow to stop the primary-to-secondary leakage and subsequent broken SG overfill and radioactive releases to the atmosphere. First, the operator is expected to determine that the SGTR has occurred and to identify and isolate the broken SG to minimize the contamination of the secondary side. The subsequent controlled RCS cooldown and depressurization are aimed to: 1) achieve the conditions that satisfy the SI termination criteria and 2) reduce the break flow. The goal of this part of the recovery procedure is to equalize the RCS and broken SG pressure in order to terminate the break flow whereas the RCS cooling is performed via intact SG using either steam dump or SG safety/or power operated relief valves. Finally, the plant cooldown and depressurization to hot and cold shutdown conditions with simultaneous depressurization of broken SG are performed. In the paper, the results of SGTR event calculation for NPP Krško using RELAP5/mod 3.3 code are presented. Various SGTR recovery scenarios regarding the availability of offsite power and subsequent operator actions were considered in the analyses. The sensitivity analyses were performed to determine the time for operator actions to prevent the steam and liquid discharge of contaminated inventory to the environment. The paper does not include the radiological consequences calculation, but based on the limited amount of the discharged fluid, they should be small.
SGTR; NPP Krško
nije evidentirano
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Podaci o prilogu
521.1-521.9.
2012.
nije evidentirano
objavljeno
978-961-6207-35-5
Podaci o matičnoj publikaciji
Proceedings of the International Conference Nuclear Energy for New Europe 2012
Žagar, Tomaž ; Fuerst, Samo
Ljubljana: Nuclear Society of Slovenia
Podaci o skupu
International Conference Nuclear Energy for New Europe 2012
poster
05.09.2012-07.09.2012
Ljubljana, Slovenija