NUCLEAR-DEBRIS FORMATION 19 _nyv (n,),$ ty ts At equilibrium (denoted by *) the net rate is zero and Away from equilibrium the equation integrates to niV _ (ns);S ty _ t, niv _ (n,)?S ty ts —t/T ° where 7 is the reduced molecular residence time t,t,/(t,+ t,). The first bracketed term is the departure from equilibrium at time t, the sec- ond is the initial departure from equilibrium, and e~‘’" is the exponen- tial decay factor. The quantity t, is frequently called the lingering time or die Verweilzeit. The temperature can be incorporated explicitly into the rate equation by means of the definition of t,and Hlickel’s expression for t,: t,= CT7%eUe/RT where U, is the molar heat of adsorption and C is a constant. This can be incorporated into the rate equation, combined witha suitable expres~ sion for temperature decay, and integrated. Particle Diffusion The fundamental formulas for heat conduction are formally identical to those previously given for diffusion in the vapor phase. The former can be written in terms of a thermal flux Jy, a thermal conductivity K, a temperature T, and a heat capacity per unit volume c: Jr =-KVT aT at? Vidr=0 By making the substitutions