Sorbent Testing for the Solidification of Organic Process Waste streams from the Radiochemical Engineering Development Center at Oak Ridge National Laboratory

The U.S. Department of Energy (DOE) has tasked MSE Technology Applications, Inc. (MSE) with evaluating various sorbents to solidify the radioactive liquid organic waste from the Radiochemical Engineering Development Center (REDC) at Oak Ridge National Laboratory (ORNL). REDC recovers and purifies heavy elements (berkelium, californium, einsteinium, and fermium) from irradiated targets for research and industrial applications. Both aqueous and organic wastestreams are discharged from REDC. Organic waste is generated from the plutonium/uranium extraction (PUREX), Cleanex, and Pubex processes. 1 The PUREX waste derives from an organic-aqueous isotope separation process for plutonium and uranium fission products, the Cleanex waste derives from the removal of fission products and other impurities from the americium/curium product, and the Pubex waste is derived from the separation process of plutonium from dissolved targets. An aqueous wastestream is also produced from these separation processes. MSE has been tasked to test a grouting formula for the aqueous wastestream that includes specially formulated radioactive shielding materials developed by Science and Technology Applications, LLC. This paper will focus on the sorbent testing work. Based on work performed at Savannah River Site (SRS) (Refs. 1, 2), ORNL tested and evaluated three sorbents capable of solidifying the PUREX, Pubex, and Cleanex wastestreams and a composite of the three organic wastestreams: Imbiber Beads® IMB230301 (Imbiber Beads), Nochar A610 Petro Bond™, and Petroset II Granular™ (Petroset II-G). Surrogates of the PUREX, Pubex, Cleanex, and a composite organic waste were used for the bench-scale testing. Recommendations resulting from the ORNL testing included follow-on testing by MSE for two of the three sorbents: Nochar Petro Bond and Petroset II-G. MSE recommended that another clay sorbent, Organoclay BM-QT-199, be added to the test sequence. The sorbent/surrogate combinations were tested at bench scale, 19-liter (L) [5-gallon (gal)] bucket scale, and 208-L (55-gal) drum scale. The testing performed by MSE will help ORNL select the right solidification materials and wasteform generation methods for the design of a new treatment facility. The results could also be used to help demonstrate that ORNL could meet the waste acceptance criteria for the ultimate disposal site for the wasteforms. The organics will be solidified as transuranic waste for disposal at the Waste Isolation Pilot Plant, and the aqueous wastestream will be grouted and disposed of at the Nevada Test Site as low-level waste if real waste testing indicates similar results to the surrogate testing. The objective of this work was to identify a sorbent capable of solidifying PUREX, Pubex, and Cleanex organic wastes individually and a composite of the three organic wastestreams. The sorbent and surrogate combinations must also be compatible with processing equipment and maintain stability under a variety of conditions that could occur during storage/shipment of the solidified wastes. 1 The extraction process wastestreams referred to as PUREX and Cleanex are not related to the commercial products known as Purex and Kleenex.