Transient Void, Pressure Drop and Critical Power BFBT Benchmark Analysis and Results with VIPRE-W/MEFISTO-T
NURETH-14 - 2011 September 25-30

Presented at:
2011 September 25-30
Toronto, Canada
Session Title:
O8-4 OECD Thermalhydraulics Benchmarks

Jean-Marie Le Corre (Westinghouse Electric Sweden AB)
Carl Adamsson (Westinghouse Electric Sweden AB)
Pablo Avarez (Westinghouse)


A benchmark analysis of the transient BFBT data [1], measured in an 8x8 fuel assembly design

under typical BWR transient conditions, was performed using the VIPRE-W/MEFISTO-T code

package. This is a continuation of the BFBT steady-state benchmark activities documented in [2]

and [3]. All available transient void and pressure drop experimental data were considered and the

measurements were compared with the predictions of the VIPRE-W sub-channel analysis code

using various modeling approaches, including the EPRI drift flux void correlation. Detailed

analyses of the code results were performed and it was demonstrated that the VIPRE-W transient

predictions are generally reliable over the tested conditions. Available transient dryout data were

also considered and the measurements were compared with the predictions of the VIPREW/

MEFISTO-T film flow calculations. The code calculates the transient multi-film flowrate

distributions in the BFBT bundle, including the effect of spacer grids on drop deposition

enhancement, and the dryout criterion corresponds to the total liquid film disappearance. After

calibration of the grid enhancement effect with a very small subset of the steady-state critical

power database, the code could predict the time and location of transient dryout with very good


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