EPR Medium Break LOCA Benchmarking Exercise Using RELAP5 and CATHARE (NUREG/IA-0459)

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Publication Information

Manuscript Completed: July 2015
Date Published: December 2015

Prepared by:
Sebastian Gurgacz, MichaƂ Pawluczyk, Piotr Mazgaj,
Piotr Darnowski, Kacper Samul, Maciej Skrzypek

Warsaw University of Technology,
Institute of Heat Engineering,
Nowowiejska 21/25,
00-665 Warsaw, Poland

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:
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Availability Notice


Thermal-hydraulic analyses are a key part in support of regulatory work for new and existing nuclear power plant design and operation. This paper describes the approach to model the Loss of Coolant Accident (LOCA) in a Light Water Reactor as part of the "Safety Analysis Report in Warsaw University of Technology" (SARWUT) project and the framework of the "Familiarization with the calculation codes application" program.

The RELAP5 model of the European Pressurized Reactor (EPR) has been developed on the basis of an available CATHARE-2 input. Both thermal-hydraulic codes, RELAP5 and CATHARE-2, are used for the safety analysis of the NPP. The purpose of this report is to present the intermediate (6-inch) cold leg break calculations performed within the benchmark exercise using both RELAP5 and CATHARE-2 codes.

The results received are satisfactory, however as presented, the calculations performed with the use of both computer codes, at the early-stage give low cladding temperature but differ in the transient characteristics. The discrepancies in the values of chosen safety related parameters are analyzed in detail for understanding and future work.

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