APPLICATION OF COMPUTATIONAL FLUID DYNAMICS TO THE DESIGN OF A WASTE VITRIFICATION FACILITY

The Hanford Waste Treatment Plant (WTP) -- the largest of its kind anywhere -- received full construction authorization from DOE in April 2003. In a waste vitrification facility, radioactive waste is combined with glass formers, heated to approximately 1200°C, and poured into stainless steel containers. The heat contained in the hot glass must be removed from the containers, and this must be accomplished within the production schedule constraints of the plant operation. In the Hanford Waste Treatment Plant, the glass is cooled in a small room, called the pour cave, in a concrete building. The room includes insulation to protect the concrete, along with ventilation and water-cooled cooling panels to facilitate heat transfer. Since earlier vitrification facilities had processed waste at a lower rate and in larger rooms, there was no readily available data on the heat release rate from vitrified glass. This paper explains why the available information on the cooling rate of the glass was of little use in predicting heat load. The container heat release rate depends on the thermal properties of the glass, which will vary as the glass recipe changes. This rate also depends on the local environment, which includes other hot containers. The cooling process is strongly coupled, and is driven by the combined mechanisms of radiation, convection, and conduction heat transfer. Computational fluid dynamics, CFD, was used to predict the heat load to the ventilation system, the cooling panels and to the insulated concrete walls for a variety of operating conditions, providing the data needed for the design of these systems. This paper describes the special techniques that were developed to simulate the pour cave operations and localized effects, presents the results of the simulations, and compares them with subsequent tests performed on containers in a similar environment.