TRACE Analysis on Heat Removal Decrease Accidents for AP1000 (NUREG/IA-0439)

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Publication Information

Manuscript Completed: September 2013
Date Published: March 2014

Prepared by:
Jong-Rong Wang, Chun-Yu Chen*, Hao-Tzu Lin, Chunkuan Shih*

Institute of Nuclear Energy Research, Atomic Energy Council, R.O.C.
1000, Wenhua Rd., Chiaan Village, Lungtan, Taoyuan, 325, Taiwan

*Institute of Nuclear Engineering and Science, National Tsing Hua University
101 Section 2, Kuang Fu Rd., HsinChu, Taiwan

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

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

Availability Notice


This research presents the applicability of TRACE to simulate AP1000's heat removal decrease accidents. The AP1000 nuclear power plant (NPP) TRACE model containing the essential components of the primary, secondary loop and passive safety systems with corresponding control systems is established through the interface code -SNAP based on the Westinghouse design. The steady-state calculation of TRACE is conducted to testify the accuracy of model and the results show a good coherent with the design parameters. Two condition II events categorized as the decrease in heat removal by secondary system are simulated and TRACEā€˜s results are consistent with Westinghouse's LOFTRAN results. The results of TRACE also reveal that the availability of reactor coolant pumps has a significant influence on the passive heat removal performance. Moreover, even without any AC power source, the passive core cooling system is capable of extracting all the core decay heat without the operator intervention. In conclusion, the passive safety system has a strong capability coping with the long-term heat removal decrease by secondary systems, further preventing the occurrence of severe consequences.

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