Drag coefficients for reactor loose parts

To estimate the range of impact velocities of potential reactor loose parts (LPs) requires information on regional flow velocities, LP mass, and LP dr ag coefficients. Flow velocities and the mass of potential LPs can generall y be bounded and therefore are assumed to be known. In this,work, drag coef ficients for prototype LP shapes, including objects suck as bolts, nuts, pi ns, and hand tools, were measured irt the fluid velocity range typical of r eactor coolant systems. Unlike drag coefficients measured for stationary ob jects, or by moving a body through a stagnant fluid, these experiments are performed on objects moving freely in a turbulent flow stream. In general, the measured drag coefficients for all tested LP shapes are shown to be clo se to the standard drag coefficient for a sphere, especially in the low-Rey nolds-number region, However, significant differences exist in the,wake tra nsition region, which indicates that the drag coefficient for a freely movi ng body in turbulent flow is different front the drag coefficient for a con fined body under the same flow conditions or for a body moving in a stagnan t fluid.