Selective separation of Pd(II) through ion exchange and oxidation-reduction with hexacyanoferrates from high-level liquid waste

2020 ◽  
Vol 231 ◽  
pp. 115932 ◽  
Author(s):  
Qilong Wang ◽  
Hongji Sang ◽  
Lifeng Chen ◽  
Yan Wu ◽  
Yuezhou Wei
Keyword(s):  
Ion Exchange ◽  
Liquid Waste ◽  
Selective Separation ◽  
High Level Liquid Waste ◽  
Oxidation Reduction ◽  
High Level

Radiocesium removal from high level liquid waste and immobilisation in sodium silicotitanate for geological disposal

2001 ◽  
Vol 89 (3) ◽  
Author(s):  
T. Tomasberger ◽  
A.C. Veltkamp ◽  
A. S. Booij ◽  
U. W. Scherer
Keyword(s):  
Ion Exchange ◽  
Fission Product ◽  
Liquid Waste ◽  
High Level Liquid Waste ◽  
Geological Disposal ◽  
Inorganic Ion ◽  
Exchange Material ◽  
Leaching Behaviour ◽  
Concentration Factors ◽  
High Level

The isolation of the fission product cesium from high-level alkaline liquid waste is studied with inorganic ion-exchange materials. High separation and concentration factors can be obtained using sodium silicotitanate (CST). The leaching behaviour of cesium from CST was studied in clay porewater and Quinary brine at 90 °C. It is shown that cesium leaching in Quinary brine can be drastically reduced by thermal treatment of cesium loaded CST above 1000 °C. To this end, neutralisation of the ion exchange material before heating is required in order to reduce cesium volatility. It is concluded that CST is a good candidate material for geological disposal of the fission product cesium.

Selective Separation and Recovery of Cesium by Ammonium Tungstophosphate-Alginate Microcapsules

2010 ◽  
Author(s):  
Hitoshi Mimura ◽  
Yan Wu ◽  
Yufei Wang ◽  
Yuichi Niibori ◽  
Isao Yamagishi ◽  
...  
Keyword(s):  
Flow Rate ◽  
High Selectivity ◽  
Liquid Waste ◽  
Selective Separation ◽  
High Level Liquid Waste ◽  
Kd Values ◽  
High Level ◽  
Alginate Matrices ◽  
Ammonium Tungstophosphate

A fine crystalline ammonium tungstophosphate (AWP) exchanger with high selectivity toward Cs+ was encapsulated in biopolymer matrices (calcium alginate, CaALG). The characterization of the AWP-CaALG microcapsule was examined using SEM/WDS, IR and DTA/TG analyses, and the selective separation and recovery of 137Cs were examined by the batch and column methods using simulated and real high-level liquid waste (HLLW). The free energy (ΔG0) of the ion exchange (NH4+ ↔ Cs+) for fine AWP crystals was determined at −13.2 kJ/mol, indicating the high selectivity of AWP towards Cs+. Spherical and elastic AWP-CaALG microcapsules (∼700 μm in diameter) were obtained and fine AWP crystals were uniformly immobilized in alginate matrices. Relatively large Kd values of Cs+ above 105 cm3/g were obtained in the presence of 10−3∼1 M Ca(NO3)2, resulting in a separation factor of Cs/Rb exceeding 102. The irradiated samples (60Co, 17.6 kGy) also exhibited large Kd values exceeding 105 cm3/g in the presence of 2.5 M HNO3. The Kd values in the presence of 0.1–9 M HNO3 for 67 elements were determined and the order of Kd value was Cs+ ≫ Rb+ > Ag+. The breakthrough curve of Cs+ had an S-shaped profile, and the breakpoint increased with decreasing flow rate; the breakpoint and breakthrough capacity at a flow rate of 0.35 cm3/min for the column (0.7 g AWP-CaALG) were estimated at 25.2 cm3 and 0.068 mmol/g, respectively. Good breakthrough and elution properties were retained even after thrice-repeated runs. The uptake (%) of Cs+ in simulated HLLW (28 metal components-1.92 M HNO3, SW-11, JAEA) was estimated at 97%, and the distribution of Cs+ and Zr/Ru into the AWP and alginate phases, respectively, were observed by WDS analysis. Further, the selective uptake of 137Cs exceeding 99% was confirmed by using real HLLW (FBR “JOYO”, JAEA). The AWP-CaALG microcapsules are thus effective for the selective separation and recovery of Cs+ from HLLWs.

Selective Uptake of Palladium From High-Level Liquid Wastes by Hybrid Microcapsules Enclosed With Insoluble Ferrocyanides

2010 ◽  
Author(s):  
Hitoshi Mimura ◽  
Takashi Sakakibara ◽  
Wu Yan ◽  
Yuichi Niibori ◽  
Shin-ichi Koyama ◽  
...  
Keyword(s):  
Sol Gel ◽  
Liquid Waste ◽  
Selective Separation ◽  
Spent Fuel ◽  
High Level Liquid Waste ◽  
Hno3 Concentration ◽  
Liquid Wastes ◽  
Gel Polymers ◽  
High Level ◽  
Cellulose Filter

Fine crystalline powders of KCuFC were immobilized with alginate gel polymers by sol-gel methods. The uptake properties of KCuFC-microcapsules (KCuFC-MC) were examined by batch and column methods. The size of KCuFC-MC particle was estimated to be about 1 mm in diameter, and KCuFC powders were uniformly dispersed in KCuFC-MC particles. The uptake rate of Pd2+ for KCuFC-MC was attained within 3 d, and the uptake of Pd2+ was found to be independent of the temperature and coexisting HNO3 concentration. As for the breakthrough properties of Pd2+ through a column packed with KCuFC-MC, a breakpoint of 5% breakthrough was enhanced with lowering of flow rate and independent of coexisting HNO3 concentration. The Pd2+ ions were selectively adsorbed in the KCuFC crystal phase, while other metal ions such as Ru(NO)3+ and ZrO2+ were absorbed in the alginate phase. High uptake percentage of 98.6% was obtained by using the dissolved solutions of spent fuel from FBR-JOYO (119 GWd/t, JAEA). The alginate film enclosing KZnFC was further prepared by using the support of cellulose filter paper, where the Pd2+ ions were selectively adsorbed on the KZnFC-MC film. The alginate film enclosing insoluble ferrocyanides are predicted for the selective separation of Pd2+ as an ion-exchange filter. Thus, the microcapsules enclosing insoluble ferrocyanides are effective for the selective separation of Pd2+ from high-level liquid waste (HLLW).

scholarly journals Vitrification of HLW Produced by Uranium/Molybdenum Fuel Reprocessing in COGEMA’s Cold Crucible Melter

2003 ◽  
Author(s):  
R. Do Quang ◽  
V. Petitjean ◽  
F. Hollebecque ◽  
O. Pinet ◽  
T. Flament ◽  
...  
Keyword(s):  
Atomic Energy Commission ◽  
Liquid Waste ◽  
Glass Layer ◽  
Cold Crucible ◽  
High Level Liquid Waste ◽  
Process Waste ◽  
Glass Formulation ◽  
High Level ◽  
Fuel Reprocessing ◽  
High Frequency Induction

The performance of the vitrification process currently used in the La Hague commercial reprocessing plants has been continuously improved during more than ten years of operation. In parallel COGEMA (industrial Operator), the French Atomic Energy Commission (CEA) and SGN (respectively COGEMA’s R&D provider and Engineering) have developed the cold crucible melter vitrification technology to obtain greater operating flexibility, increased plant availability and further reduction of secondary waste generated during operations. The cold crucible is a compact water-cooled melter in which the radioactive waste and the glass additives are melted by direct high frequency induction. The cooling of the melter produces a soldified glass layer that protects the melter’s inner wall from corrosion. Because the heat is transferred directly to the melt, high operating temperatures can be achieved with no impact on the melter itself. COGEMA plans to implement the cold crucible technology to vitrify high level liquid waste from reprocessed spent U-Mo-Sn-Al fuel (used in gas cooled reactor). The cold crucible was selected for the vitrification of this particularly hard-to-process waste stream because it could not be reasonably processed in the standard hot induction melters currently used at the La Hague vitrification facilities: the waste has a high molybdenum content which makes it very corrosive and also requires a special high temperature glass formulation to obtain sufficiently high waste loading factors (12% in molybednum). A special glass formulation has been developed by the CEA and has been qualified through lab and pilot testing to meet standard waste acceptance criteria for final disposal of the U-Mo waste. The process and the associated technologies have been also being qualified on a full-scale prototype at the CEA pilot facility in Marcoule. Engineering study has been integrated in parallel in order to take into account that the Cold Crucible should be installed remotely in one of the R7 vitrification cell. This paper will present the results obtained in the framework of these qualification programs.

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