United States Nuclear Regulatory Commission - Protecting People and the Environment

Assessment of LONF ATWS for Mananshan PWR Using TRACE Code (NUREG/IA-0436)

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Publication Information

Manuscript Completed: September 2013
Date Published: February 2014

Prepared by:
Jong-Rong Wang, Che-Hao 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

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Abstract

The objective of this study is to utilize TRACE code to analyze the reactor coolant system (RCS) pressure transients under LONF (Loss of Normal Feedwater) ATWS (Anticipated Transient Without Scram) for Maanshan PWR. TRACE is an advanced thermal hydraulic code for nuclear power plant safety analysis which is developed by U.S. NRC. Maanshan nuclear power plant (NPP) is a Westinghouse three-loop PWR in Taiwan. The rated core thermal power of Maanshan with MUR-PU (Measurement Uncertainty Recapture Power Uprate) is 2822 MWt. According to Westinghouse anticipated transients without trip report, LONF ATWS was regarded as the most severe plant condition. The ASME Code Level C service limit criteria of 22.06 MPa (3200 psig) was assumed to be an unacceptable plant condition in SECY-83-293.

In order to conform to 10 CFR 50.62, Maanshan NPP has set up AMSAC that is diverse from reactor trip system to automatically initiate the auxiliary feedwater system and initiate a turbine trip under conditions indicative of an ATWS. Since the ATWS analysis is not specified in the FSAR, we use TRACE code to assess the RCS pressure for Maanshan NPP. The results indicate that RCS pressure could keep within 22.06 MPa with sufficient negative moderator temperature coefficient (MTC) and normal work of AMSAC and valves.

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