Phase Compositions and Elements Partitioning in Two-Phase Hosts for Immobilization of a Rare Earth-Actinide High-Level Waste Fraction

1999 ◽  
Vol 608 ◽  
Author(s):  
S.V. Stefanovsky ◽  
S.V. Yudintsev ◽  
B.S. Nikonov ◽  
A.V. Ochkin ◽  
S.V. Chizhevskaya ◽  
...  
Keyword(s):  
Rare Earth ◽  
High Level Waste ◽  
Two Phase ◽  
High Level

Development of Actinide-Containing Waste Immobilization Process

2003 ◽  
Author(s):  
S. V. Stefanovsky ◽  
A. G. Ptashkin ◽  
Y. M. Kuliako ◽  
S. A. Perevalov ◽  
S. V. Yudintsev ◽  
...  
Keyword(s):  
Rare Earth ◽  
Glass Ceramics ◽  
Radiation Stability ◽  
Ore Deposits ◽  
High Level Waste ◽  
Nuclear Accidents ◽  
Two Phase ◽  
Preparation Methods ◽  
Waste Forms ◽  
High Level

Actinide wastes involve actinide or rare earth–actinide fractions of high level waste (HLW), Pu-contaminated materials, including incinerator ashes, excess weapons plutonium, and some wastes formed during plutonium conversion in MOX fuel and nuclear accidents. SIA Radon in cooperation with Vernadsky Institute of Geochemistry, Institute of Geology of Ore Deposits, and D. Mendeleev University of Chemical Technology deals with development and testing of actinide waste forms and preparation methods. Zirconolite, pyrochlore, and murataite are considered as host phases for plutonium and other actinides. Two-phase ceramics based on zirconolite-perovskite, pyrochlore-perovskite, perovskite–cubic zirconia-based solid solution, murataite-perovskite, and zirconolite-murataite assemblages were designed for incorporation of actinide and rare earth–actinide fractions of HLW. Glass-ceramics containing apatite-britholite phases have been proposed for incinerator ash fixation. All these matrices have high chemical durability and radiation stability. The most promising method for production of these waste forms is an inductive melting in a cold crucible. Cold pressing and sintering technology is considered as alternative route. Mechanical activation intensifies ceramization process and reduces sintering temperature. Some new methods such as selfsustaining synthesis and plasma melting are being also examined.

Phases Formation and Elements Partitioning in the CaO-Gd2O3(UO2)-MnO-TiO2 System: Application to Rare Earth - Actinide Waste Immobilization

2002 ◽  
Vol 757 ◽  
Author(s):  
Olga I. Kirjanova ◽  
Sergey V. Stefanovsky ◽  
Sergey V. Yudintsev
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Corrosion Products ◽  
High Level Waste ◽  
Major Phase ◽  
Reducing Conditions ◽  
Transmission Electron ◽  
Unit Cells ◽  
Coupled Substitution ◽  
High Level

ABSTRACTCeramics within the compositional series Ca4-xGdxMn2Ti7O20+x/2 (x = 0, 1, 2, 3, 4) and a sample with Ca2U2Ti7O20 formulation were studied as promising matrices for immobilization of rare earth (RE) and actinide (An) constituents of high level waste (HLW). The samples were prepared by cold pressing of oxide mixtures in pellets at 200 MPa followed by their sintering at 1400 °C or melting at 1500 °C and examined with X-ray diffraction, scanning and transmission electron microscopy. At x=0 and x=1 a perovskite – pyrophanite assemblage occurred. The sample with x=2 consisted of murataite and perovskite. Murataite was a major phase in the sample with x=3 (pyrochlore and perovskite were minor phases) and the only phase in the sample with x=4 prepared under oxidizing conditions (in air). The latter was composed of two murataite varieties with seven- and five-fold fluorite unit cells. The sample with the same formulation but synthesized under reducing conditions contained pyrochlore as an extra phase. Coupled substitution 2 Gd3+ = Ca2+ + U4+ resulted in formation of pyrochlore as the major phase. Mu-rataite and perovskite are considered as the host phases for rare earths and actinides mainly trivalent, including Pu(III), Am(III), and Cm(III), and corrosion products (Mn, Fe, Al) whereas pyrochlore is the host phase for rare earths and tetravalent actinides (U(IV), Np(IV), Pu(IV)). This makes the system of calcium, gadolinium, manganese, and titanium oxides prospective for immobilization of RE – An fraction of HLW containing minor corrosion products (iron group elements).

Phase distribution of uranium in matrices for immobilization of the rare earth–actinide fraction of high-level waste

2015 ◽  
Vol 57 (6) ◽  
pp. 640-651 ◽  
Author(s):  
S. V. Yudintsev ◽  
S. V. Stefanovsky ◽  
O. I. Stefanovskaya ◽  
B. S. Novikov ◽  
M. S. Nikol’skii
Keyword(s):  
Rare Earth ◽  
Phase Distribution ◽  
High Level Waste ◽  
High Level ◽  
The Rare Earth

Murataite Ceramics Doped with Lanthanides and Uranium

2005 ◽  
Vol 893 ◽  
Author(s):  
Sergey Stefanovsky ◽  
S.V. Yudintsev ◽  
B.S. Nikonov ◽  
O.I. Stefanovsky
Keyword(s):  
Rare Earth ◽  
Phase Composition ◽  
Rare Earth Elements ◽  
Mixed Oxides ◽  
Perovskite Phase ◽  
Unit Cell ◽  
Intermediate Zone ◽  
High Level Waste ◽  
High Level ◽  
The Rare Earth

AbstractPhase composition of the murataite-based ceramics containing 10 wt.% of mixed oxides simulating rare earth/actinide (REE/An) and actinide (An) fractions of high level waste (HLW) was studied. The ceramics were prepared by melting of oxide mixtures in Pt ampoules in air at ∼1500 °C. Ceramics with REE/An and An fractions surrogates are composed of predominant murataite-type phases and minor extra phases: perovskite and crichtonite. Three murataite-related phases with five- (5C), eight- (8C), and three-fold (3C) elementary fluorite unit cell are present in these ceramics. These phases form core, intermediate zone, and rim of the murataite grains, respectively. They are predominant host phases for the rare earth elements and uranium whose concentrations are reduced in a row: M-5C>M-8C>M-3C. Appreciate fraction of Ce, Nd, and Pu may enter the perovskite phase. In the An-Gd ceramic perovskite and murataite were found to be predominant and secondary in abundance phases respectively.

Formation of secondary phases after long-term corrosion of simulated HLW glass in brine solutions at 190 °C

2002 ◽  
Vol 90 (9-11) ◽  
Author(s):  
P. Zimmer ◽  
E. Bohnert ◽  
Dirk Bosbach ◽  
Jae-Il Kim ◽  
E. Althaus
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Glass Powder ◽  
High Level Waste ◽  
Secondary Phases ◽  
Batch Experiments ◽  
Salt Solutions ◽  
Glass Corrosion ◽  
High Level

SummaryThe behavior of rare earth elements (REE) as chemical analogues for actinides during glass corrosion was studied with static long-term batch experiments (7.5 years) at 190 °C. Corrosion tests were carried out using a simulated inactive high level waste (HLW) glass powder. Two different highly concentrated salt solutions (NaCl-rich and MgCl

A polyphase geoceramic matrix for joint immobilization of the strontium-cesium and rare earth fractions of high-level waste

2015 ◽  
Vol 57 (2) ◽  
pp. 200-206 ◽  
Author(s):  
R. A. Kuznetsov ◽  
N. V. Platonova ◽  
R. V. Bogdanov
Keyword(s):  
Rare Earth ◽  
High Level Waste ◽  
High Level

Interactions of Simulated High Level Waste (HLW) Calcine with Alkali Borosilicate Glass

2003 ◽  
Vol 807 ◽  
Author(s):  
S. Morgan ◽  
R. J. Hand ◽  
N. C. Hyatt ◽  
W. E. Lee
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Borosilicate Glass ◽  
Glass Frit ◽  
High Level Waste ◽  
Second Stage ◽  
Mixed Alkali ◽  
High Level ◽  
Simulated High Level Waste ◽  
Fuel Reprocessing

ABSTRACTThis study looks at the interactions between simulated calcined high level waste from fuel reprocessing and mixed alkali borosilicate glass frit in the early stages of melting, and the possibility of the formation of yellow phase during these stages. Simulant “calcine” from a full scale inactive trial (Magnox: oxide “blend” 25:75) was pre-mixed with alkali borosilicate glass, to achieve a 25wt% waste loading, and melted at 1050°C at various times. It is shown that dissolution occurs in two separate stages; the first involves formation of a low density CsLiMoO4 fluid, which separates and forms a yellow/green layer on the surface of the melt, accompanied by some dissolution of rare- earth elements (Nd, Ce, Gd) and Zr from the waste into the glass matrix. The second stage entails more extensive migration of these rare-earth elements into the glass, and the disappearance of the surface layer on the melt. The glass appears more homogenized at the later stages of melting, but still contains undissolved particles of calcine after 16 minutes.

Turbulent Impinging Flow Simulation for High-Level Waste Storage and Processing Applications

2007 ◽  
Author(s):  
S. Rhea ◽  
M. Fairweather
Keyword(s):  
Fluid Dynamic ◽  
Flow Simulation ◽  
Turbulent Jets ◽  
Solid Particles ◽  
High Level Waste ◽  
Data Sets ◽  
Two Phase ◽  
Stagnation Line ◽  
Waste Storage ◽  
High Level

The efficient storage and processing of high-level nuclear waste could be improved by a better understanding of the behaviour of the particle-laden fluid flows involved. This work reports a mathematical modelling study of impinging single- and two-phase turbulent jets that is of relevance to the flows used industrially to prevent the settling of solid particles in storage tanks, and to re-suspend particles that form a bed. A computational fluid dynamic model, that embodies a Lagrangian particle tracking technique, is applied to the prediction of these flows. Predictions in the free flow and wall regions, and along the stagnation line, of the single-phase flow are in reasonable accord with data, although the addition of particles results in less satisfactory agreement between predictions and measurements. The influence of particles is, however, reproduced qualitatively by the mathematical model, with quantitative differences attributable to a lack of particle drag in the simulations. Uncertainties in experimental parameters may be responsible for some of the differences between predictions and data, and examination of the data used casts doubts on its reliability. Further work is required in terms of the use of more advanced turbulence modelling techniques, and the provision of detailed and reliable data sets.

Plutonium Incineration in LWR's by a Once-Through Cycle with a Rock-Like Fuel

1995 ◽  
Vol 412 ◽  
Author(s):  
C. Degueldre ◽  
U. Kasemeyer ◽  
F. Botta ◽  
G. Ledergerber
Keyword(s):  
Rare Earth ◽  
Zirconium Oxide ◽  
Single Phase ◽  
High Level Waste ◽  
Spent Fuel ◽  
Natural Analogue ◽  
Promising Candidate ◽  
Inert Matrix ◽  
The Stability ◽  
High Level

AbstractPlutonium incineration in a uranium-free fuel by a once-through burning cycle in LWR’s followed by geological disposal of the rock-like material as a high level waste is discussed here. For burning plutonium of various origins, zirconium oxide is a promising candidate as inert matrix because it is stabilised by rare earth oxides (Er, Ho, Eu … Y) in a single phase solid solution with a stable cubic structure. In this material, selected rare earth isotopes can also act as burnable poisons. The spent fuel may be licensed as waste material on the basis of the inventory, the stability of the material and the behaviour of natural analogue material (e.g. baddeleyite). A fuel composed of 90-80% ZrO2, 7–14% PuO2 and 3–6% Er2O3 (At%), with potential addition of Y2O3 (as additional stabiliser), is suggested for experimental study. Such a fuel employed in LWR's could generate power effectively while transmuting about 95% of the 239Pu

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

2018 ◽  
Author(s):  
Sergey E. Vinokurov ◽  
Svetlana A. Kulikova ◽  
Boris F. Myasoedov
Keyword(s):  
Rare Earth ◽  
Radioactive Waste ◽  
Rare Earth Elements ◽  
Liquid Radioactive Waste ◽  
Hydrolytic Stability ◽  
Research Work ◽  
Dynamic Test ◽  
Potassium Phosphate ◽  
High Level Waste ◽  
High Level

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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