Self-propagating high-temperature synthesis for immobilization of high-level waste in mineral-like ceramics: 2. Immobilization of cesium in ceramics based on perovskite and zirconolite

Баринова, Т. В.; Borovinskaya, I. P.; Ратников, В. И.; Игнатьева, Т. И.

doi:10.1134/s1066362208030193

Cited by 11 publications

(3 citation statements)

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“…The release of energy and temperature in the course of SHS can be controlled by matching of a reductant (Ti, Zr)-oxidant (åÓé 3 , CuO, Fe 2 O 3 , or íÒ 2 é 7 in our case) pair and by choice of their proportions (Kuprin, 2002;Barinova et al, 2008). Anyway, the estimation of the degree of Tc evaporation in the course of SHS requires preliminary testing.…”

Section: Production Of Matrices For Immobilization Of Technetium Withmentioning

confidence: 99%

“…Using SHS, it is possible to obtain matrices containing such volatile components as Mo and Cs with temperatures of melting at 800°ë (MoO 3 ) and sublimation at 400°ë (Cs 2 O). It is established that volatilization of Cs during production of crystalline matrices for HLW with SHS depends on the type and content of oxidant in the charge (Barinova et al, 2008). With an optimal choice of mixture, the loss of Cs was only ~10%.…”

Section: Production Of Matrices For Immobilization Of Technetium Withmentioning

confidence: 99%

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Isolation of long-lived technetium-99 in confinement matrices

2009

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Amongst fission products formed in atomic reactors, 99 Tc is the most hazardous for the environment because of its long half-life (213000 yr), high content in spent nuclear fuel (SNF) (0.8-1.0 kg per ton of SNF), low sorption ability, and high mobility under aerobic conditions. The bulk of 99 Tc (~200 t) is incorporated into SNF. In the course of SNF reprocessing, this radioisotope is released as a separate fraction or along with actinides. More than 60 t of highly concentrated 99 Tc have been accumulated to date. It is evident that isolation of 99 Tc from the environment is a matter of great urgency. The immobilization of technetium in a highly stable and poorly soluble matrix is a necessary element in settling this problem. Ceramics composed of titanates with pyrochlore, perovskite, and rutile structures are proposed as matrices able to retain technetium along with actinides. The high chemical stability of these compounds has been corroborated by experiments. The difficulties in production of such matrices are related to the fugacity of Tc and the necessity of converting it into Tc(IV). To overcome this obstacle, self-propagating high-temperature synthesis (SHS), characterized by reductive conditions and a high reaction rate, is proposed. The charge for matrix synthesis consists of reducing agents (metallic powders with a strong affinity to oxygen, e.g., Ti and Zr), oxidants (MoO 3 , Fe 2 O 3 , CuO), and additives (TiO 2 , ZrO 2 , Y 2 O 3 , CaO, etc.), which taken together with other elements form target phases. Instead of Tc, Mo, close in chemical properties, is used in matrix synthesis as a simulator. Samples of Mo-bearing matrices have been synthesized with SHS; their phase compositions and Mo distribution therein are characterized. It has been shown that up to 40 wt % Mo can be incorporated into the synthesized matrices in the form of metal or structural admixtures in titanates. The titanate-zirconate pyrochlore-based matrices are the most appropriate for the joint immobilization of actinides, REEs, and 99 Tc.

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Section: Production Of Matrices For Immobilization Of Technetium Withmentioning

confidence: 99%

Section: Production Of Matrices For Immobilization Of Technetium Withmentioning

confidence: 99%

Isolation of long-lived technetium-99 in confinement matrices

2009

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“…The final waste form can remain in place without transportation and disposal. Especially, the method has a low investment for facility construction, and it is suitable particularly for small volume hazardous wastes, including calcined radioactive, contaminated clay soils, ash, and spent inorganic ion exchange materials [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] .…”

Section: Introductionmentioning

confidence: 99%

Self-Propagating High-Temperature Synthesis for Immobilization of Simulated Radioactive Sandy Soil Waste

Qin

Mao

Chen

et al. 2012

AMR

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The immobilization of simulated radioactive sandy soil waste by using self-propagating high-temperature synthesis (SHS) was investigated. The products were characterized by density, X-ray diffraction, and scanning electron microscope. The leaching rate of tracer element was measured by the method of PCT (product consistency test). The SHS immobilization typically results in products containing amorphous phase and crystalline phase. The volume density of the final product is over 3.0g/cm3. The tracer element Ce in the final product mainly forms crystalline phase of CeAl11O18 and Ce2SiO5 when the amount of CeO2 in the raw material is large than 1%. The leaching rate of Ce for 28 days is about 10-5 g•m-2•d-1，which is much lower than that of the borosilicate glass solid form. the leaching rates of Ca, Si, Al and Fe during 28 days are about 10-3～10-4 g•m-2•d-1

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On the Exploitation of Self-Propagating High-Temperature Reactions for Environmental Protection

Orrù

Cao

2014

Current Environmental Issues and Challenges

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Self-propagating high-temperature synthesis for immobilization of high-level waste in mineral-like ceramics: 2. Immobilization of cesium in ceramics based on perovskite and zirconolite

Cited by 11 publications

References 0 publications

Isolation of long-lived technetium-99 in confinement matrices

Isolation of long-lived technetium-99 in confinement matrices

Self-Propagating High-Temperature Synthesis for Immobilization of Simulated Radioactive Sandy Soil Waste

On the Exploitation of Self-Propagating High-Temperature Reactions for Environmental Protection

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