Simulation of Total Loss of Feedwater LOFT LP-FW-1 Test using RELAP5/MOD3.3 (NUREG/IA-0526)

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Publication Information

Manuscript Completed: November 2020
Date Published: August 2021

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)

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After Fukushima-Daiichi in the Europe the design extension conditions (DEC) were introduced as preferred method for giving due consideration to the complex sequences and severe accidents without including them in the design basis conditions. The purpose of this study was to assess the latest RELAP5/MOD3.3 Patch 05 computer code for the simulation of such DEC. The LP-FW-01 test performed in 1983 on the Loss of Fluid Test Facility (LOFT) has been used for simulation. The LP-FW-01 test represents a fault sequence in which a total loss of feedwater to the steam generator is followed by recovery by primary system feed-and-bleed. The RELAP5/MOD3 steady state input deck available from literature has been adapted to RELAP5/MOD3.3 Patch 05, while transient input deck to simulate LP-FW-01 test has been newly developed. The simulation results for short term response (0-300 s) and long term response (0-7000 s) are presented in the report. The results suggest that in the short term simulation of LP-FW-1 test the simulated results matches the major events very good. In the long term the simulation results suggest that the entrainment to the surge line is important for the correct results.

Page Last Reviewed/Updated Monday, August 30, 2021