LOCAs With Loss of One Active Emergency Cooling System Simulated by RELAP5 (NUREG/IA-0516)

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Publication Information

Manuscript Completed: November 2019
Date Published: January 2020

Prepared by:
Andrej Prošek

Jožef Stefan Institute
Jamova cesta 39
SI-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:
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

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The second generation reactors were designed and built to withstand without loss to the structures, systems, and components necessary to ensure public health and safety during design basis accidents. There are also accident sequences that are possible but were judged to be too unlikely and therefore were not fully considered in the design process of second generation reactors. In that sense, they were considered beyond the scope of design-basis accidents that a nuclear facility must be designed and built to withstand. They were called beyond design basis accidents. After Fukushima-Daiichi in the Europe the design extension conditions were introduced as preferred method for giving due consideration to the complex sequences and severe accidents without including them in the design basis conditions. In the study, the analysis was performed to see if the plant design can prevent spectrum of loss of coolant accidents together with the complete loss of one emergency core cooling function (e.g. high pressure injection or low pressure injection). The analyzed break spectrum ranged from 1.27 cm to 30.48 cm. For calculations the latest RELAP5/MOD3.3 Patch 5 has been used and the RELAP5 input model of Krško nuclear power plant.

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