Experimental Investigation of Subcooled Flashing Flow in Simulated Cracks

In this study an experimental program was developed to measure the choking flow rate of subcooled water through simulated tube crack geometries (L/D<10 L< 5mm) and results are compared with models in literature. A test facility was designed and built to measure leak rates of subcooled water from through-wall simulated tube cracks up to 6.8 MPa. Two types of test specimens were used in the experimental program. One, a round orifice like hole is created to simulate a pitting type flaw. The others are laser cut slits representing axial cracks. Flow discharge tests were carried out with water at room temperature to determine the flow characteristics for each test specimen. Also, subcooled flashing discharge tests with heated water were carried out up to a vessel pressure of 6.8 MPa at various subcoolings. A modified Burnell correlation was developed using upstream saturation and subcooled temperature conditions and the predictions of the correlation agreed well with the present experimental data.Copyright © 2011 by ASME