Development of SGTR Recovery Strategy

Conference · Thu Jul 01 04:00:00 EDT 2004

OSTI ID:21160636

Lee, Ju Han; Kim, Se Chang; Sohn, Jong Joo; Seo, Jong Tae ^[1]

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1. Korea Power Engineering Company Inc., 150 Deogjin-dong, Yuseong-gu, Daejeon, 305-353 (Korea, Republic of)

The Steam Generator Tube Rupture (SGTR) recovery guideline of the Korean Standard Nuclear Power Plant (KSNP) Emergency Operating Guidelines (EOG) provides operator actions which must be accomplished in the event of a SGTR. The goal of the guideline is to safely establish Shutdown Cooling System (SCS) entry conditions while minimizing radiological releases to the environment and maintaining adequate core cooling. The current KSNP SGTR EOG uses the strategy that requires immediate rapid cooldown of Reactor Coolant System (RCS) using Atmospheric Dump Valves (ADVs) on both steam generators to a temperature lower than the saturation temperature corresponding to the lowest Main Steam Safety Valves (MSSVs) opening setpoint, followed by an isolation of the affected steam generator. This strategy helps to prevent unnecessary lifting and possible stuck-open of MSSVs on the affected steam generator side after isolation. Generally, the safety analysis for SGTR is performed based on the automatic mitigation actions provided by the engineered safety features and operator actions as directed in the SGTR EOG. For a conservatism, this analysis assumes a Loss of Off-site Power (LOOP) and a postulated single-failure of stuck-open ADV which is used for the initial rapid RCS cooldown. However, a concern on the radiological release through the stuck-open ADV can be eliminated by changing the SGTR recovery strategy. Therefore, a feasibility study has been performed to develop a new SGTR recovery strategy which requires an immediate isolation of the affected steam generator followed by a rapid cooldown of RCS using the ADV on the intact steam generator only. The results of the analyses have been evaluated from the standpoint of the total amount of radiological release to the environment and the possibility of overfill of the affected steam generator. The best-estimate analysis results with the new SGTR recovery strategy show that the amount of radiological release to the environment can be reduced and the time that the affected steam generator reaches the maximum indicated level can be delayed as compared to the former strategy although the possibility of MSSV lift after isolation increases. (authors)

• Research Organization: American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
• OSTI ID: 21160636
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
ACCIDENTS
COOLING
FEASIBILITY STUDIES
NUCLEAR POWER PLANTS
REACTOR COOLING SYSTEMS
RECOMMENDATIONS
RELIEF VALVES
RUPTURES
SAFETY
SAFETY ANALYSIS
SATURATION
SHUTDOWN
STANDARDS
STEAM GENERATORS