This report was prepared as a part of the ERDA-funded HTGR Safety Research Task. It fulfills a major task milestone of documenting a newly developed PCRV plateout code developed for the analysis of core heatup accidents. The scope of the report is restricted to the assumptions, equations, and solution techniques of the first operational version of the computer program. The data base, application of the code to core heatup accidents, and comparisons with previous methods will be addressed in a separate report as a future milestone.
The behavior of some of the prominent fission products along their convection pathways is dominated by the interaction of other species with them. This gave rise to the development of a plateout code capable of analyzing coupled species effects. The single species plateout computer program PADLOC is described in Part I of this report. The present Part II is concerned with the extension of PADLOC to MULTI*PADLOC, a multiple species version of PADLOC. MULTI*PADLOC is designed to analyze the time and one-dimensional spatial dependence of the concentrations of interacting (fission product) species in the carrier gas and on the surrounding wall surfaces on an arbitrary network of flow channels. The problem solved is one of mass transport of several impurity species in a gas, including the effects of sources in the gas and on the surface, convection along the flow paths, decay interaction, sorption interaction on the wall surfaces, and chemical reaction interactions in the gas and on the surfaces. These phenomena are governed by a system of coupled, nonlinear partial differential equations. The solution is achieved by, a) linearizing the equations about an approximate solution and employing a Newton-Raphson iteration technique, b) employing a finite difference solution method with an implicit time integration, and c) employing a substructuring technique to logically organize the systems of equations for an arbitrary flow network.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.