Identifying challenge sludges to process at the Hanford site

The nuclear waste at the Hanford site represents one of the single largest environmental cleanup efforts currently underway. Decades of nuclear weapons production have produced a highly radioactive sludge waste. Effective disposition of this waste will require processing the sludge to reduce the overall volume of the final waste form. Because of the expense and difficulty in obtaining samples from these tanks, a method was developed to assess the relative difficulty associated with treating waste through either crossflow filtration or settling. By assessing the relationship between centrifuged solids loading and sample chemistry, it was possible to identify which tanks would pose the greatest challenge for these processing methods. Tanks with >200,000 microg/g of Al or >49,000 microg/g of P were identified as at risk for poor separation performance and represent nearly 50% of the high-volume sludge tanks. As such, altering the process approach or blending the difficult-to-process feeds with a less challenging feed are recommended for the processing of these wastes.