United States Nuclear Regulatory Commission - Protecting People and the Environment

An Assessment of TRACE V4.160 Code Against PACTEL LOF-10 Experiment (NUREG/IA-0237)

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Publication Information

Date Published: June 2010

Prepared by:
J. Vihavainen

Lappeenranta University of Technology
Department of Energy and Environmental Technology
Laboratory of Nuclear Engineering
P.O.B. 20
53851 Lappeenranta
Finland

Antony 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)

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

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Abstract

This report has been written as an International Agreement Report under the Thermal Hydraulic Code Applications and Maintenance Program (CAMP) coordinated by the United States Nuclear Regulatory Commission. The calculations presented in the report comprise an assessment case which is a part of the in-kind contribution of Finland to the CAMP program. The assessed case was to first build up a TRACE thermal hydraulic code simulation model for horizontal steam generator of the Parallel Channel Test Loop (PACTEL) facility. Secondly, the case consisted of calculations to test the TRACE code capabilities. A loss-of feedwater, LOF-10, experiment was chosen for this assessment. The calculation results showed that the TRACE code is capable in simulating the horizontal steam generator behavior both in steady state and during loss-of feedwater transient. Three models with different nodalization were introduced. The calculation results differed from experiment to some extent. At the final state the calculated secondary side collapsed level decrease was more than in the experiment. The heat transfer from primary to the secondary side degraded gradually during the uncovery of the heat exchange tubes. The calculations overestimated this heat transfer. In the experiment the steam started to superheat immediately when the uppermost tube layer had uncovered. The steam superheating in the calculations was possible only after the uppermost cell on the secondary side had voided thoroughly. Because of the use of lumped pipe representation of the heat exchange pipes in the calculations the timing of the superheating initiation was much later than in the experiment with the coarse nodalization models. More detailed representation of the heat exchange tubes gave more accurate results.

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