Magnesium Potassium Phosphate Compound for Radioactive Waste Immobilization: Phase Composition, Structure, and Physicochemical and Hydrolytic Durability

Винокуров, С. Е.; Kulikova, Svetlana A.; Krupskaya, V. V.; Myasoedov, Β. F.

doi:10.1134/s1066362218010125

Cited by 28 publications

(21 citation statements)

References 20 publications

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“…The composition of this phase can be represented in general form (Mg,K,Cs)PO4 × nH2O, where Cs content is 0.3-0.6 at% ( Table 1). In this case, there were separate particles of a phase containing phosphorus and cesium up to 38 at%, that confirmed the formation of the CsH2PO4 phase (it is shown in Figure 1a), and there were separate particles of cesium orthophosphate Cs3PO4 (on the example of particles in Phase #2, Figure 2, Table 1) in compound, as we showed in earlier work [24]. The SEM micrograph of the surface of the MPP compound containing CsCl is shown in Figure 2, and the average EDS results of the found phases are presented in Table 1.…”

Section: -Mgkpo4 × 6h2o (K-struvite); 2 -Mgcspo4 × 6h2o; 3 -Csh2po4; supporting

confidence: 87%

“…The synthesis of the MPP matrix was carried out according to the procedure previously described in the manuscript [24], by solidification of aqueous solutions of CsCl (salinity-540 g/L) and LiCl-KCl-CsCl with a ratio of 41.6%-52.9%-5.5% (as a surrogate of spent electrolyte, according to the manuscript [10]). The samples were prepared at the MgO: H 2 O:KH 2 PO 4 weight ratio of 1:2:3.…”

Section: Chemicals and Proceduresmentioning

confidence: 99%

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

et al. 2020

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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 137Cs 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/(cm2·day) (GOST R 52126-2003), and was 4–29 × 10−7 g/(cm2∙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.

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Section: -Mgkpo4 × 6h2o (K-struvite); 2 -Mgcspo4 × 6h2o; 3 -Csh2po4; supporting

confidence: 87%

Section: Chemicals and Proceduresmentioning

confidence: 99%

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

et al. 2020

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“…As a result of potassium replacement with metals of nitric acid solutions, the KNO3 (niter) phase (the characteristic peaks at 3.78, 3.74, 3.04 Å) is formed in the obtained compounds (Figure 1), that was also shown previously in [9,10]. However, it was not possible to identify this phase in compound #1 (Figure 1a) by XRD method, probably because of its small content (theoretically not more than 5 wt%), but its presence is clearly confirmed by microanalysis data (phase N in Figure 2b).…”

Section: Slope Of the Linessupporting

confidence: 83%

“…The chemicals used in the experiments were of no less than chemically pure grade. Samples of MKP compounds were prepared according to the procedure previously given in [10]. The phase composition and structure of the prepared MKP compounds were determined by X-ray diffraction (XRD) (Ultima-IV, Rigaku).…”

Section: Methodsmentioning

confidence: 99%

“…Previously we and other researchers demonstrated [9][10][11][12][13][14][15][16] that magnesium potassium phosphate (MKP) compound based on the MgKPO4 × 6H2O matrix obtained as a result of the reaction (1), which is an analog of the natural mineral K-struvite [17], is promising low-temperature material for the immobilization of various RW types.…”

Section: Introductionmentioning

confidence: 99%

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Magnesium Potassium Phosphate Compound for Immobilization of Radioactive Waste Containing Actinide and Rare Earth Elements

Винокуров

Kulikova

Myasoedov

2018

Preprint

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The problem of effective immobilization of liquid radioactive waste (LRW) is key to the successful development of nuclear energy. The possibility of using magnesium potassium phosphate (MKP) compound for LRW immobilization on the example of nitric acid solutions containing actinides and rare earth elements (REE), including high level waste (HLW) surrogate solution is considered in the research work. Under the study of phase composition and structure of the MKP compounds obtained by the XRD and SEM methods, it was established that the compounds are composed of crystalline phases - analogues of natural phosphate minerals (struvite, metaankoleite). The hydrolytic stability of the compounds was determined according to the semi-dynamic test GOST R 52126-2003. Low leaching rates of radionuclides from the compound are established, including a differential leaching rate of 239Pu and 241Am - 3.5 × 10-7 and 5.3 × 10-7 g/(cm2∙day). As a result of the research work it was concluded that the MKP compound is promising for LRW immobilization and can become an alternative material combining the advantages of easy implementation of the technology like cementation and the high physical and chemical stability corresponding to a glass-like compound.

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New Methods and Materials in Nuclear Fuel Fabrication and Spent Nuclear Fuel and Radioactive Waste Management

Винокуров

Kulikova²,

Frolova³

et al. 2023

Advances in Geochemistry, Analytical Chemistry, and Planetary Sciences

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Magnesium Potassium Phosphate Compound for Radioactive Waste Immobilization: Phase Composition, Structure, and Physicochemical and Hydrolytic Durability

Cited by 28 publications

References 20 publications

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

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

Magnesium Potassium Phosphate Compound for Immobilization of Radioactive Waste Containing Actinide and Rare Earth Elements

New Methods and Materials in Nuclear Fuel Fabrication and Spent Nuclear Fuel and Radioactive Waste Management

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