The development of an advanced model to determine the dynamic pump per
formance under two-phase flow conditions is presented. This model is i
ncluded in CATHARE 2, version V1.3. It is based on the two-fluid six-e
quation CATHARE model which describes the mechanical and thermal non-e
quilibria. In a previous review (P. Van den Hove and G. Geffraye, The
CATHARE code - one-dimension pump model, Fifth Int. Topical Meet. on N
uclear Reactor Thermal Hydraulics (NURETH-5), Salt Lake City, USA, Sep
tember, 1992), various calculations were presented concerning Eva sing
le-phase and two-phase steam-water test results in the first three qua
drants. Here, the range of assessment of the first quadrant is enlarge
d with Eva air-water tests and Bethsy pump steam-water tests. Both pum
ps are mixed flow pumps, the Bethsy one being radial at the impeller o
utlet. Some improvements suggested in the above cited paper are tested
against all single-phase liquid, single-phase vapor, two-phase steam-
water, and two-phase air-water data in the first quadrant. They concer
n a new deviation model and head losses model, and the model of mechan
ical interaction between phases.