2016-Sustainable Industrial Processing Summit
SIPS 2016 Volume 9: Molten Salts and Ionic Liquids, Energy Production
| Editors: | Kongoli F, Gaune-Escard M, Turna T, Mauntz M, Dodds H.L. |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2016 |
| Pages: | 390 pages |
| ISBN: | 978-1-987820-24-9 |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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Electrochemical Extraction of Ans and Lns from FLiNaK Eutectic Salt
Huang Wei1;1, Shanghai, China;
Type of Paper: Regular
Id Paper: 107
Topic: 13
Abstract:
Electrochemical technology is an important procedure for processing spent nuclear fuel due to its potential advantages: compactness, compatibility with diverse fuel types, and ability to produce low purity products which benefit to non-proliferation. In this work, the electrochemical behaviors of Ans and Lns in LiF-NaF-KF (FLiNaKŁ¬46.5-11.5-42.0 mol%) were investigated, based on which the electrodeposition experiments were conducted.
The experimental results indicated that U4+ was reduced to metallic uranium through two steps: U4+ was first reduced to U3+ at -1.42 V (vs Ni2+/Ni) followed by U3+ reduction to U0 at -1.82 V (vs Ni2+/Ni); In contrast, reduction of Th4+ to Th0 was a simple four-electron transfer mechanism occurring at -1.80 V (vs Ni2+/Ni). The electrolysis experiments were performed in FLiNaK-UF4 and FLiNaK-ThF4 eutectic salts. Metallic uranium and UO2 were the major products on Ni cathode when FLiNaK-UF4 was electrolyzed, which contain more than 30wt% uranium; the electrolysis of FLiNaK-ThF4 revealed the formation of metallic thorium on Pt electrode in spite of the relatively low yield and separation efficiency. The experimental results show the feasibility for the recovery of U and Th from fluoride molten salt using the electrochemical method.
The electrochemical behaviors of several Lns were also studied. The results show that the reduction of Y3+, Gd3+, and Nd3+ in FLiNaK exhibits three electrons transfer from Ln3+ to Ln0, but in the case of Sm3+ and Eu3+, only one electron transfer process was observed, which indicates that the reduction from Sm3+ˇuSm2+ and Eu3ˇuEu2+ occurs.