RELAP5/MOD3.3 Analysis of Event with Actuation of Safety Injection System at the Loss of External Power (NUREG/IA-0458)

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Publication Information

Manuscript Completed: November 2014
Date Published: December 2015

Prepared by:
A. Prošek, M. Matkovič

Jožef Stefan Institute
Jamova cesta 39
Sl-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


Measured plant data are of great importance for the assessment of thermal-hydraulic system codes. Namely, the integral effects facilities contain atypicalities and scaling distortions relative to full scale plants. On the other hand, the accidents in the plants are very rare and the plant specific data are generally available only for startup tests and operational events. However, the measured plant data may be limited for the full understanding of event. The purpose of this study was therefore both code assessment and better understanding of the plant response to abnormal event, which occurred on 23 March 2011 in Krško nuclear power plant (NPP). The abnormal event was called "Reactor trip and actuation of safety injection system at the loss of external power". For the analysis the latest RELAP5/MOD3.3 Patch 04 best-estimate thermalhydraulic computer code and standard Krško NPP input deck for RELAP5 have been used. The results show good agreement between measured and simulated data, when all plant system responses and operator actions were considered. This suggests that the RELAP5 code using standard plant input deck is good representative of the plant and could be used for better understanding of the plant response when information on all physical phenomena and processes is not available by plant measured data.

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