[en] An analytical model was developed to allow preditions of the source term to the containment as dependent on release from the fuel pins and deposition within the primary system. The model was developed into a flexible computer code adaptable to various geometrical arrangements and flow paths. The calculational framework was established in such a way to permit, in principle, the determination of particle and vapor transport and deposition in a general system of control volumes connected by fluid flow in an arbitrary way. This framework requires as input the rate of fission product release to the primary flow, as a function of time for each vapor and particulate species to be considered, and a complete, time dependent, thermal-hydraulic description of the system. TRAP-PWR, TRAP-BWR and TRACK computer codes are specializations, described in detail in the text of this report, of the general framework. The nature of these specializations depends strongly on the degree of detail with which the transporting fluid medium is modeled