United States Nuclear Regulatory Commission - Protecting People and the Environment

Heat Transfer Processes During Intermediate and Large Break Loss-of-Coolant Accidents (LOCAs) (NUREG/IA-0002)

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Publication Information

Date Published: September 1986

Prepared by:
I. Vojtek

Reactor Safety Corporation
Gesellschaft fuer Reaktorsicherheit
Porschungsgelaende, 8046 Garching,
The Federal Republic of Germany

Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555

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Abstract

The general purpose of this project was the- investigation of the heat transfer regimes during the high pressure portion of blowdown. The main attention has been focussed on the evaluation of those phenomena which are most important in reactor safety, such as maximum and minimum critical heat flux and forced convection film boiling heat transfer. The experimental results of the 25-rad bundle blowdown heat transfer tests, which were performed at the KWU heat transfer test facility in Karistein, were used as a database for the verification of different correlations which are used or were developed for the analysis of reactor safety problems. The computer code BRUDI-VA was used for the calculation of local values of Important thermohydraulic parameters in the bundle.

In particular the following correlations have been evaluated in this study:

Maximum critical heat flux:

  • W-3 correlation
  • B-W-2 correlation
  • Macbeth correlation
  • Zuber-GriffIth correlation
  • Biasi correlation
  • CISE correlation
  • Slifer-GE correlation
  • Smolin correlation
  • Pong correlation
  • Thorgerson correlation
  • Monde-Katto correlation

Minimum critical heat flux and minimum film boiling temperature:

  • Berenson modification of the Zuber correlation
  • Berenson correlation
  • Henry correlation
  • Iloeje correlation

Heat transfer coefficients in flow film boiling:

  • modified Dougal l-Rohsenow correlation
  • Groeneveld-5.7 correlation
  • Condie-Bengston-IV correlation
  • Groeneveld-Delorme correlation
  • Chen-Ozkaynak-Sundaram correlation.

The evaluation of correlations for the prediction of critical heat flux, film boiling heat transfer coefficients and minimum film boiling temperature showed that none of the correlations should be used over the entire range of test parameters investigated.

Using results of this investigations a new equilibrium correlation for the calculation of forced film boiling heat transfer coefficients has been developed. This correlation is shown to agree well. with the experimental data over the following range of testparameter: Mass flow rate 300 to 1400 kg/m2.s, pressure 2 to 12 MPa and quality 0.3 to 1.0.

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