Discussion on model validation

PROFESSOR SIMPSON (Paper 9): Figures 1-3 show three-dimensional representations of the varia tions with time and space in the downcomer tube of pressure, mass velocity, void fraction, respectively.

MR B. CHOJNOWSKI, CEGB, Marchwood Engineering Laboratories: It has been said that the voidage correlations used significantly under predict the measured voidage. I believe this arises be cause the existing correlations refer to the interactions between phases while what happens in a PWR steam generator reflects the voidage that is functionally dependent on tube support geometry. Would Dr Kalra comment on this point in the light of observations made on the one seventh scale Freon model of the PWR steam generator.