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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.

Hydrogen generation from catalyzed solutions of sodium borohydride has been demonstrated experimentally up to 10 MPa. Sodium borohydride solutions are nonflammable, stable in basic solution, and offer a volumetric hydrogen density of 63.2 gH2/l. In the presented work, the reaction rate data for catalyzed hydrolysis of sodium borohydride solutions as a function of hydrogen static pressure are coupled with a polymer electrolyte membrane fuel cells model. It has been shown that the elevated hydrogen pressure can bring the solution to equilibrium and tends to return to equilibrium upon pressure decrease. The model considers hydrogen demand from a fuel cell and the response of the high pressure hydrogen generator in terms of a mass balance. It is shown that 2–4 g of Co3B is adequate to hydrolyze 60 l of 30 wt %NaBH4 solution.