On the Dispersion of Fission Products from Laminar Streams in Open- and Closed-Loop Conduits

Two simplified models which describe the deposition of fission products from laminar gas streams on the surface of a cylindrical conduit are formulated for both open- and closed-loop systems. A uniform source is assumed to release a precursor into a gas stream. Solutions are obtained for the deposition of the precursor and its associated daughter products.

The boundary value problem consisting of two coupled partial differential equations for each nuclear species is analyzed for two models. The two models, which arise due to the imperfect sink condition at the tube surface for impinging particles, are termed “The Resistance Model” and “The Transport Model.” Both models are approximate and the range of their validity is discussed.

The closed-form solutions obtained with the two simplified models provide a good insight to the effects of various parameters on deposition of fission products in closed-loop systems and on the deposition of daughter products both in open- and closed-loop systems.