Tank waste treatment

Once the waste has been retrieved to the maximum extent practicable, the next step is to separate it chemically and physically into two fractions: the higher-volume portion that contains shorter-lived, less radioactive elements (i. e., LAW) and a much smaller fraction that contains longer-lived, radioac­tive elements (i. e., HAW). The two fractions are then treated separately to convert them to stable, solid forms. The LAW is proposed to be disposed of onsite, and the HAW is proposed to be disposed of offsite in a geological repository.

The Salt Waste Processing Facility (SWPF) and the Waste Treatment and Immobilization Plant (WTP) are being constructed at SRS and Hanford, respectively, to treat and immobilize radioactive tank waste. SRS is com­pleting the design and construction of the SWPF. The SWPF will separate the LAW and HAW fractions, solidifying the former as a grout in the exist­ing Saltstone facility for disposal onsite in large vaults. The HAW fraction will be sent to the Defense Waste Processing Facility (DWPF), which has operated since 1996, where it will be converted to a stable glass form using vitrification. DWPF has vitrified HAW into 3,325 canisters as of December 2011 that are stored onsite in special-purpose facilities awaiting disposal in a geological repository.

To maintain the compliance-driven schedule for closing SRS tanks and to address risk more quickly, SRS began operating two interim tank-waste processing facilities (the Actinide Removal Process and the Modular Caustic Side Solvent Extraction Unit) in advance of SWPF startup to sepa­rate out LAW for onsite disposal. The DOE continues to pursue strategies to optimize the capacity of these facilities to complete treatment of the tank waste in a cost-effective manner.

The WTP, now under construction at Hanford, will also separate the LAW and HAW tank fractions. It will then vitrify the two waste frac­tions, with the LAW disposed of onsite and the HAW disposed of in a geological repository. Operation of the WTP facility is scheduled to begin in 2019.

The remaining INL tank waste will be treated in the Integrated Waste Treatment Unit (IWTU) at the Sodium Bearing Waste Treatment Facility forming a crystalline ceramic (mineral) waste form by fluidized bed steam reforming for ultimate disposal at WIPP. A vitrification plant constructed at West Valley has converted the radioactive tank waste there into 275 canisters of glass.

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