Assessment of RELAP5/MOD3.2.2? Against Flooding Database in Horizontal-to-Inclined Pipes (NUREG/IA-0203)

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Publication Information

Date Published: July 2001

Prepared by:
H.T. Kim, H.C. No
Korea Advanced Institute of Science and Technology
373-1, Gusung-Dong, Yusung-Ku, Taejon 305-701 Korea

S.J. Ha, N.S. Ahn
Korea Electric Power Research Institute
103-16 Munji-Dong, Yusung-Ku, Taejon 305-380 Korea

Y.S. Bang
Korea Institute of Nuclear Safety
PO Box 114, Yuseong-Gu, Taejon 305-600 Korea

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
under the International Code Application and Maintenance Program (CAMP)

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

Availability Notice


A total of 356 experimental data for the onset of flooding are compiled for the data bank and used for the assessment of RELAP5/MOD3.2.2γ predictions of Counter-Current Flow Limitation (CCFL) in horizontal-to-inclined pipes simulating a PWR hot leg.

RELAP5 calculations show that higher gas flow rates are required to initiate the flooding compared with the experimental data if the L/D is as low as that of the hot legs of typical PWRs.

Based on the present data bank, the new CCFL correlation is derived, which shows the L/D effect. The present correlation agrees well with the database within the prediction error, 8.7% and it is implemented into the RELAP5 and validated against the data bank.

The predictions of the flooding limit by the modified version lie well on the applied CCFL curve even ifithe predictions by standard RELAP5 are lower than the present CCFL curve.

Key Words: RELAP5/MOD3.2, CCFL, Flooding Database

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