Conditioning of Spent Electrolyte Surrogate LiCl-KCl-CsCl Using Magnesium Potassium Phosphate Compound

Svetlana A. Kulikova, Kseniya Yu. Belova, Ekaterina A. Tyupina and Sergey E. Vinokurov
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Svetlana A. Kulikova: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin st., 119991 Moscow, Russia
Kseniya Yu. Belova: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin st., 119991 Moscow, Russia
Ekaterina A. Tyupina: Department of High Energy Chemistry and Radioecology, D. Mendeleev University of Chemical Technology of Russia (MUCTR), 125480 Moscow, Russia
Sergey E. Vinokurov: Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 19 Kosygin st., 119991 Moscow, Russia

Energies, 2020, vol. 13, issue 8, 1-11

Abstract: The current work was aimed at developing a new conditioning method of spent electrolyte-radioactive waste (RW) generated during the pyrochemical reprocessing of mixed nitride uranium-plutonium spent nuclear fuel. Magnesium potassium phosphate (MPP) compound samples were synthesized under solidification of the electrolyte surrogate solution in a LiCl-KCl-CsCl system. The phase composition and structure of obtained compounds were studied by XRD and SEM-EDS methods. It was found that the compounds possessed a high compressive strength of 17–26 MPa. Hydrolytic stability of the compounds was evaluated in accordance with the long semi-dynamic test GOST R 52126-2003 and with the static PCT test. The 137 Cs content in the leached solutions was determined by gamma-ray spectrometry, and other compound components were determined by ICP–AES and ICP–MS methods. The differential leaching rate of Cs at 25 °C from monolithic samples on the 91st day of samples contact with water was 5–11 × 10 −5 g/(cm 2 ·day) (GOST R 52126-2003), and was 4–29 × 10 − 7 g/(cm 2 ?day) on the 7th day at 90 °C from crushed samples (PCT). The thermal stability of the compound at 180 °C and 450 °C was shown. The characteristics of the obtained MPP compound correspond to the current regulatory requirements for materials for RW conditioning.

Keywords: magnesium potassium phosphate compound; radioactive waste; spent electrolyte; cesium; chlorides; zeolite; conditioning; compressive strength; leaching; thermal stability (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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