Weir model to relate the liquid flow rate with the water level in an inverted u-bend

When a small-break loss-of-coolant accident occurs in a Babcock and Wilcox reactor, instantaneous information on the water loss is quite important. Moreover, because a higher liquid level over the inverted U-bend is usually associated with a higher liquid flow rate, a Weir model can be developed as a way of measuring flow rate from the liquid in the U-bend. The Weir model is derived from the Bernoulii equation by assuming the phase separation is complete during passage of the fluid flow through the top of the bend. An advantage of using this model is that it enables one to predict the volumetric liquid flow rate by measuring the height of the water level on top of the bend