Coupled RELAP/PARCS Full Plant Model – Assessment of a Cooling Transient in Trillo Nuclear Power Plant (NUREG/IA-0255)

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Publication Information

Manuscript Completed: November 2010
Date Published: August 2011

Prepared by:
J. C. Martínez-Murillo1, M. Novo1, R. Miró2, T. Barrachina2, and G. Verdú2

1Almaraz-Trillo AIE
Av Manoteras 46Bis, 28050 Madrid

2 Institute for Industrial, Radiophysical and Environmental Safety (ISIRYM)
Universitat Politècnica de València
Camí de Vera, s/n
46022 Valencia, SPAINM

A. Calvo, NRC Project Manager

Prepared as part of:
The agreement on technical exchange and cooperation between the Consejo de Seguridad Nuclear (CSN) of Spain and the U.S. Nuclear Regulatory Commission (NRC) in the field of nuclear safety research.

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

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This report presents the methodology to change from a 0-D kinetics core in a RELAP5/Mod3.3 full plant model of Trillo NPP to a coupled RELAP5/PARCS 3-D core. The coupled plant model is assessed against a real cooling transient that deformed the core power axial profile.

The coupled steady state core model was adjusted to a CASMO/SIMULATE calculation by condensing the cross-sections with the SIMTAB methodology. The need of information exchange between RELAP and PARCS during the transient was the reason for two modifications of the coupling between both codes.

  • The CASMO/SIMULATE calculation of the initial core conditions correspondent to the date of the transient was performed by Iberdrola Ingeniería.
  • The SIMTAB methodology used to build the PARCS input file, the automated tools for core input files mapping and the RELAP/PARCS modifications of control rod and boron content were performed by the Nuclear Engineering Group belonging to the Institute for Industrial, Radiophysical and Environmental Safety (ISIRYM) at the Universitat Politècnica de València (UPV).
  • The modifications to the RELAP5 full plant model to couple the 3-D PARCS core, the steady-state adjustments of PDDs, and the transient calculation and analysis were performed by the Thermo-Hydraulic group of Almaraz-Trillo NPPs.

The results of the transient show an almost perfect agreement with plant data for all the compared variables. The comparison of in-core parameters evolution with plant data is also very good and the 3-D simulation allows to perform a more detailed analysis of core behaviour.

This report was prepared by the Thermo-Hydraulic group of Almaraz-Trillo NPPs (CNAT), with the help of the Polytechnic University of Valencia.

The Asociación Española de la Industria Eléctrica (UNESA, Electric Industry Association of Spain) and Almaraz-Trillo NPPs AIE sponsored this work.

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