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Analysis of SBO ATWS for Maanshan PWR

  • Che-Hao Chen , Jong-Rong Wang , Hao-Tzu Lin , Shao-Wen Chen and Chunkuan Shih
Published/Copyright: November 2, 2015
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Abstract

Station blackout anticipated transient without scram (SBO ATWS) is considered as loss of off-site and on-site power but no credit for automatic reactor trip. SBO ATWS causes reactor coolant pump (RCP) trip, loss of all main feedwater pumps and turbine trip, then the reactor coolant system (RCS) pressure rises rapidly due to loss of heat removal paths. The ASME Code Level C service limit criteria of 22.06 MPa (3200 psig) is assumed to be an unacceptable plant condition in SECY-83-293. The simulation is performed by TRACE which is a thermal-hydraulic code developed by U.S. NRC. Three different AFW flows are modeled to ensure the pressures will not be beyond the criteria. RCP seal-leakage is concerned as a SBLOCA due to loss of RCP seal-cooling. Four possible leakage flows are modeled to examine the reactor core water level and temperature variation.

Kurzfassung

Ein vollständiger Ausfall der ungesicherten Wechselstromversorgung (Station Blackout, SBO) in Verbindung mit einer zu erwartenden Transiente ohne Reaktorschnellabschaltung (ATWS) wird betrachtet. SBO ATWS verursacht den Ausfall der Kühlmittelpumpen, der Hauptspeisewasserpumpen und einen Turbinenschnellschluss. Durch den Ausfall der Wärmeabfuhrpfade steigt der Druck im Reaktorkühlsystem schnell an. Der ASME Code Level C Druckgrenzwert von 22.06 MPa ist ein unzulässiger Anlagenzustand nach SECY-83-293. Die Simulation wurde mit Hilfe des Thermohydraulik-Codes TRACE durchgeführt. Drei verschiedene Ströme des Hilfsspeisewassersystems werden modelliert, um sicherzustellen, dass die Druckwerte nicht jenseits dieses Kriteriums liegen. Die Dichtungsleckage an den Kühlmittel pumpen wird als Kühlmittelverluststörfall mit kleinem Leck angenommen. Vier mögliche Leckageströme wurden modelliert, um den Wasserstand im Reaktorkern und die Temperaturschwankungen zu untersuchen.


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Received: 1900-01-01
Published Online: 2015-11-02
Published in Print: 2015-10-29

© 2015, Carl Hanser Verlag, München

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