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TRACE simulations of LOCAs Together with the Complete Loss of One Emergency Core Cooling Function in Two-Loop PWR (NUREG/IA-0554)

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Publication Information

Manuscript Completed: November 2024
Date Published: February 2025

Prepared by:
Andrej Prošek

Jožef Stefan Institute
Jamova cesta 39
SI-1000, Ljubljana, Slovenia

K. Tien, NRC Project Manager

Division of Systems Analysis
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Prepared as part of
Prepared as part of The Agreement on Research Participation and Technical Exchange
Under the Thermal-Hydraulic Code Applications and Maintenance Program (CAMP)

Published by:
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Availability Notice

Abstract

After Fukushima Dai-ichi accident Western European Association of Nuclear Regulators (WENRA) and the International Atomic Energy Agency (IAEA) require due consideration of design extension conditions (DEC). The purpose of this report is to study the loss of coolant accident (LOCA) together with the complete loss of one emergency core cooling function in two-loop pressurized water reactor (PWR). Such multiple failure has been recognized by WENRA and IAEA documents as possible DEC.

For analysis the U.S. Nuclear Regulatory Commission (U.S. NRC) TRAC/RELAP Advanced Computational Engine (TRACE) computer was used. The TRACE input deck has been developed based on the conversion of verified and validated RELAP5 standard input deck for a two-loop pressurized water reactor (PWR). In the study high- or low-pressure injection system was assumed to be lost. Other safety systems were assumed available. The LOCA calculations have been performed for a spectrum of break sizes in the cold leg. The results showed that DEC safety feature is needed for smaller breaks in scenarios with loss of high-pressure injection. Finally, simulations demonstrated that in the scenarios assuming DEC safety feature the significant core heatup has been prevented.

Page Last Reviewed/Updated Friday, February 14, 2025