Application of TRACE V5.0 P2 to Natural Circulation Reactor Safety Analysis (NUREG/IA-0418)

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Publication Information

Manuscript Completed: February 2012
Date Published: October 2012

Prepared by:
FENG Jinjun, CHAI Guohan, SHI Junying, ZHOU Kefeng

Nuclear and Radiation Safety Centre
Ministry of Environmental Protection
54, Honglian Nancun, Haidian District
Beijing, 100082, CHINA

A. Calvo, NRC Project Manager

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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The purpose of this work is to study the behavior of natural circulation reactor under Accident scenario using the TRACE (TRAC/RELAP Advanced Computational Engine) code. The work is divided into five parts:

The first part is TRACE model establishment. SNAP (Symbolic Nuclear Analysis Program) program was used to facilitate system modeling work. Important components such as core and heat exchanger were modeled respectively. These components were tested separately and results were compared with design data to check the accuracy. Key parameters were indentified and properly adjusted to refine the model further. All of the components were incorporated together to build up the integrated TRACE model of natural circulation reactor.

The second part is steady state calculation. Steady state of full power operation was simulated by TRACE code and calculation results were compared with design data. Hydraulic frictions were adjusted to keep calculated and designed primary side natural circulation mass flow as close as possible. The adjustment work was iterated until all of key parameters were acceptable.

The third part is transient calculation. The Accident scenario “Loss of Main Feed Water” was simulated in this part. Restart case of accident scenario was prepared based on the steady state TRACE model established previously. The transient calculation results showed that safety goal was achieved under the assumed accident scenario.

The forth part is sensitivity analysis. Sensitivity analysis of main feed water flow rate and reactor power to primary side natural circulation flow was performed respectively. Special phenomenon of natural circulation flow acceleration due to “loss of feed water” was understood better though the sensitivity analysis.

The last part is accident scenario animation. SNAP was used to create the animation of the “Loss of Main Feed Water” Accident scenario. Better understanding of the calculated physical phenomena and transient process was obtained via animation demonstration.

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