United States Nuclear Regulatory Commission - Protecting People and the Environment

Simulation of the Experimental Series F2.2 at PKL Facility Using RELAP5/Mod 3.3 (NUREG/IA-0411)

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Publication Information

Manuscript Completed: November 2011
Date Published: February 2012

Prepared by:
S. Carlos, J. F. Villanueva, S. Martorell, V. Serradell

Universidad Politécnica de Valencia
Departamento de Ingeniería Química y Nuclear
Camino Vera s/n
46022 Valencia, SPAIN

A. Calvo, NRC Project Manager

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
Under the Thermal-Hydraulic Code Applications and Maintenance Program (CAMP)

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

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Abstract

The reactor coolant system water level is reduced when a nuclear power plant is in shutdown conditions for refuelling. This situation is known as mid-loop operation, and the residual heat removal (RHR) system is used to remove the decay power heat generated in the reactor core.

In mid-loop conditions, some accidental situations may occur with a nonnegligible contribution to the plant risk, and all involve the loss of the RHR system. Thus, to better understand the thermalhydraulic processes following the loss of the RHR during shutdown, transients of this kind have been simulated using best-estimate codes in different integral test facilities. In PKL facility different series of experiments have been undertaken to analyse the plant response in shutdown. In this context, the F2 series consists of analyzing the loss of residual heat removal under ¾ loop operation with closed primary circuit. In particular test F2.2 has been developed to investigate the influence of the configuration of the secondary side (i.e. number of SGs filled with water and ready for activation) on the heat transfer mechanisms in the U-tubes of the SGs and study the boron dilution process in critical parts of the primary circuit. Two experiments belonging to this experimental series have been performed, F2.2 RUN1 and F2.2 RUN2. The simulations present differences in number of steam generators filled and ready for operation. Thus for RUN1 there is one steam generator filled with water and controlled at 2 bar and in RUN2 there are two steam generators SGs filled with water and controlled at 2 bar.

This work focuses on the simulation, using the best estimate code RELAP5/Mod 3.3, of both of the Runs of the experiment F2.2 conducted at the PKL facility.

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