ANALYSIS OF WALL-PACKED BED THERMAL INTERACTIONS

One of the major issues remaining for ceramic breeder blankets involve s uncertainties in heat transfer and thermomechanical interactions wit hin the breeder and multiplier regions, Particle bed forms are conside red in many reactor blanket designs for both the breeder and Be multip lier. The effective thermal conductivity of beds and the wall-bed ther mal conductance are still not adequately characterized, particularly u nder the influence of mechanical stresses. The problem is particularly serious for the wall conductance between Be and its cladding, where t he uncertainty can be greater than 50%. In this work, we describe a ne w model for the wall-bed conductance that treats the near-wall region as a finite-width zone. The model includes an estimate of the region p orosity based on the number of contact points, and the contact area fo r smooth surfaces. It solves the heat conduction in a near-wall unit c ell. The model is verified with existing data and used to predict the range of wall conductances expected in future simulation experiments a nd in reactor applications.