Proof-of-concept flowsheet tests for cesium removal from tank waste by caustic-side solvent extraction

David B. Chamberlain, Scott Aase, Hassan A. Arafat, Cliff Conner, Ralph A. Leonard, Monica C. Regalbuto, George F. Vandegrift

Research output: Contribution to journalConference articlepeer-review

Abstract

A caustic-side solvent extraction (CSSX) process to remove cesium from Savannah River Site (SRS) high-level waste has been developed through a joint program with Oak Ridge National Laboratory (ORNL), the Savannah River Technical Center (SRTC), and Argonne National Laboratory (ANL). The CSSX solvent consists of four components: (1) an extractant, a calixarene crown, calix[4]arene-bis(tert-octylbenzo-crown-6) designated BOBCalixC6, (2) a modifier, an alkyl aryl polyether, 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, also called Cs-7SB, (3) a suppressant, an alkyl amine, trioctylamine (TOA), and (4) a diluent, Isopar®L. The solvent composition is 0.01 M BOBCalixC6, 0.50 M Cs-7SB, and 0.001 M TOA in Isopar®L. In this program we have developed and demonstrated a flowsheet that can be used to process SRS tank waste. To this end, a series of flowsheet tests were completed using simulated waste in a 2-cm centrifugal contactor at ANL. Three short-term (3-4 hours) tests were completed to demonstrate various aspects of the flowsheet. These tests were followed by a 71-h test where the solvent was recycled 42 times. In each case, we met or exceeded the key process goals: (1) cesium removal from the waste with a decontamination factor greater than 40,000, (2) concentration of cesium in the aqueous strip effluent by a factor of 15 using dilute nitric acid, and (3) stripping the solvent sufficiently to allow it to be recycled many times. The results from the 71-h test are discussed.

Original languageBritish English
Pages (from-to)877-884
Number of pages8
JournalMaterials Research Society Symposium - Proceedings
Volume713
DOIs
StatePublished - 2002
EventScientific Basis for Nuclear Waste Management XXV - Boston, MA, United States
Duration: 26 Nov 200129 Nov 2001

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