TY - JOUR

T1 - Universal solvent extraction (Unex) flowsheet testing for the removal of cesium, strontium, and actinide elements from radioactive, acidic dissolved calcine waste

AU - Herbst, R. Scott

AU - Law, Jack D.

AU - Todd, Terry A.

AU - Romanovskiy, Valeriy N.

AU - Babain, Vasily A.

AU - Esimantovskiy, Vyatcheslav M.

AU - Smirnov, Igor V.

AU - Zaitsev, Boris N.

PY - 2002/7/1

Y1 - 2002/7/1

N2 - The presence of long-lived radionuclides presents a challenge to the management of radioactive wastes. Separation of the radionuclides from the waste solutions has the potential of significantly decreasing the costs associated with the immobilization and disposal of the radioactive waste by minimizing waste volumes. Typically, several separate processes are required for the separation of cesium, strontium, and actinides from radioactive wastes. A novel solvent extraction process, the Universal Extraction (UNEX) process, has been developed for the simultaneous separation of cesium, strontium, and the actinides from radioactive acidic waste solutions. The UNEX process solvent consists of chlorinated cobalt dicarbollide for the extraction of 137Cs, polyethylene glycol for the extraction of 90Sr, and diphenyl-N,N-di-n-butylcarbamoylmethyl phosphine oxide for the extraction of the actinides and lanthanides. A non-nitroaromatic polar diluent, phenyltrifluoromethyl sulfone, is used for this process. A UNEX flowsheet consisting of a single solvent extraction cycle has been developed as a part of a collaborative effort between the Khlopin Radium Institute (KRI) and the Idaho National Engineering and Environmental Laboratory (INEEL). This flowsheet has been demonstrated with actual dissolved radioactive calcine waste at the INEEL using 24 stages of 2-cm diameter centrifugal contactors installed in a shielded hot cell facility. For the major radionuclides, 99.99% of the 137Cs, 99.73% of the 90Sr, and >99.9% of the actinides in the initial dissolved calcine feed were extracted and recovered in the high activity fraction. For the stable matrix elements, 12% of the Mo, 0.7% of the Zr, and 2% of the Fe were extracted and recovered in the strip product. The minor components Ba and Pb were quantitatively extracted and recovered in the strip product; 23% of the Mn was also present in this fraction. Very little Al, Ca, Cr, Na, and Ni were extracted into the UNEX solvent.

AB - The presence of long-lived radionuclides presents a challenge to the management of radioactive wastes. Separation of the radionuclides from the waste solutions has the potential of significantly decreasing the costs associated with the immobilization and disposal of the radioactive waste by minimizing waste volumes. Typically, several separate processes are required for the separation of cesium, strontium, and actinides from radioactive wastes. A novel solvent extraction process, the Universal Extraction (UNEX) process, has been developed for the simultaneous separation of cesium, strontium, and the actinides from radioactive acidic waste solutions. The UNEX process solvent consists of chlorinated cobalt dicarbollide for the extraction of 137Cs, polyethylene glycol for the extraction of 90Sr, and diphenyl-N,N-di-n-butylcarbamoylmethyl phosphine oxide for the extraction of the actinides and lanthanides. A non-nitroaromatic polar diluent, phenyltrifluoromethyl sulfone, is used for this process. A UNEX flowsheet consisting of a single solvent extraction cycle has been developed as a part of a collaborative effort between the Khlopin Radium Institute (KRI) and the Idaho National Engineering and Environmental Laboratory (INEEL). This flowsheet has been demonstrated with actual dissolved radioactive calcine waste at the INEEL using 24 stages of 2-cm diameter centrifugal contactors installed in a shielded hot cell facility. For the major radionuclides, 99.99% of the 137Cs, 99.73% of the 90Sr, and >99.9% of the actinides in the initial dissolved calcine feed were extracted and recovered in the high activity fraction. For the stable matrix elements, 12% of the Mo, 0.7% of the Zr, and 2% of the Fe were extracted and recovered in the strip product. The minor components Ba and Pb were quantitatively extracted and recovered in the strip product; 23% of the Mn was also present in this fraction. Very little Al, Ca, Cr, Na, and Ni were extracted into the UNEX solvent.

UR - http://www.scopus.com/inward/record.url?scp=0036660953&partnerID=8YFLogxK

U2 - 10.1081/SEI-120014366

DO - 10.1081/SEI-120014366

M3 - Article

AN - SCOPUS:0036660953

VL - 20

SP - 429

EP - 445

JO - Solvent Extraction and Ion Exchange

JF - Solvent Extraction and Ion Exchange

SN - 0736-6299

IS - 4-5

ER -