(280a) Developments in the Integrated Flowsheet for Treating Hanford's Radioactive and Hazardous Liquid Waste

Approximately 56 million gallons of radioactive and hazardous waste is stored in underground tank farms at Hanford in southeastern Washington state.  This waste arose from the production of plutonium during the Second World War and Cold War for use in nuclear weapons.  The waste is currently in the form of sludgies, precipitated salts and concentrated salt solutions but needs to be treated and immobilized into a form suitable for disposal.  The plan agreed between the State of Washington, the Federal Government and the Environmental Protection Agency and established as the River Protection Project (RPP) is to retrieve the waste, separate it into high and low radioactive portions and vitrify both for disposal.  The low radioactive portion, Low Activity Waste (LAW), will be dispositioned at Hanford in a near-surface, engineered burial trench while the highly radioactive portion, high level waste, will be dispositioned in a federal geologic repository.  Key to this strategy is the Waste Treatment and Immobilization Plant (WTP) currently under construction at Hanford.  The first phase of the RPP, Direct Feed Low Activity Waste (DFLAW), is to pretreat and immobilize a fraction of the concentrated salt solutions.  This presentation will discuss the DFLAW process flowsheet, describing the integration between the WTP and the tank farms, its gaps and its opportunities for optimization.  Development of a cohesive set of waste acceptance criteria for the inter-related processing plants is key for efficient operations.  The presentation will discuss the development of a number of these, including for the tank farms and the waste processing plants.