The possibility exists that the core liquid level can be depressed qua
si-statically during long-term plant cooldown following a cold-leg-bre
ak loss-of-coolant accident in a pressurized-water reactor. Such a lev
el depression can take place if the core steaming rate is almost balan
ced with the steam condensation rate in the reactor coolant system (RC
S). Integral experiments simulating three steam condensation modes in
the RCS have shown that quasi-static level depressions can happen and
thus have the potential for causing a prolonged uncovery and heatup of
the core upper regions.