Hydrolytic and thermal stability of magnesium potassium phosphate compound for immobilization of high level waste

2018 ◽  
Vol 318 (3) ◽  
pp. 2401-2405 ◽  
Author(s):  
Sergey E. Vinokurov ◽  
Svetlana A. Kulikova ◽  
Boris F. Myasoedov
Keyword(s):  
Thermal Stability ◽  
Potassium Phosphate ◽  
High Level Waste ◽  
Phosphate Compound ◽  
High Level ◽  
Thermal Stability Of

scholarly journals Optimization of the Solidification Method of High-Level Waste for Increasing the Thermal Stability of the Magnesium Potassium Phosphate Compound

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3789
Author(s):  
Svetlana A. Kulikova ◽  
Sergey S. Danilov ◽  
Kseniya Yu. Belova ◽  
Anastasiya A. Rodionova ◽  
Sergey E. Vinokurov
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Compressive Strength ◽  
Potassium Phosphate ◽  
Treatment Temperature ◽  
High Level Waste ◽  
Leaching Rate ◽  
High Level ◽  
The Impact ◽  
Thermal Stability Of

The key task in the solidification of high-level waste (HLW) into a magnesium potassium phosphate (MPP) compound is the immobilization of mobile cesium isotopes, the activity of which provides the main contribution to the total HLW activity. In addition, the obtained compound containing heat-generating radionuclides can be significantly heated, which increases the necessity of its thermal stability. The current work is aimed at assessing the impact of various methodological approaches to HLW solidification on the thermal stability of the MPP compound, which is evaluated by the mechanical strength of the compound and its resistance to cesium leaching. High-salt surrogate HLW solution (S-HLW) used in the investigation was prepared for solidification by adding sorbents of various types binding at least 93% of 137Cs: ferrocyanide K-Ni (FKN), natural zeolite (NZ), synthetic zeolite Na-mordenite (MOR), and silicotungstic acid (STA). Prepared S-HLW was solidified into the MPP compound. Wollastonite (W) and NZ as fillers were added to the compound composition in the case of using FKN and STA, respectively. It was found that heat treatment up to 450 °C of the compound containing FKN and W (MPP-FKN-W) almost did not affect its compressive strength (about 12–19 МPa), and it led to a decrease of high compressive strength (40–50 MPa) of the compounds containing NZ, MOR, and STA (MPP-NZ, MPP-MOR, and MPP-STA-NZ, respectively) by an average of 2–3 times. It was shown that the differential leaching rate of 137Cs on the 28th day from MPP-FKN-W after heating to 250 °C was 5.3 × 10−6 g/(cm2∙day), however, at a higher temperature, it increased by 20 and more times. The differential leaching rate of 137Cs from MPP-NZ, MPP-MOR, and MPP-STA-NZ had values of (2.9–11) × 10−5 g/(cm2∙day), while the dependence on the heat treatment temperature of the compound was negligible.

scholarly journals Solidification of high level waste using magnesium potassium phosphate compound

2019 ◽  
Vol 51 (3) ◽  
pp. 755-760 ◽  
Author(s):  
Sergey E. Vinokurov ◽  
Svetlana A. Kulikova ◽  
Boris F. Myasoedov
Keyword(s):  
Potassium Phosphate ◽  
High Level Waste ◽  
Phosphate Compound ◽  
High Level

scholarly journals Effect of Fe2O3 on the Immobilization of High-Level Waste with Magnesium Potassium Phosphate Ceramic

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Hailin Yang ◽  
Mingjiao Fu ◽  
Bobo Wu ◽  
Ying Zhang ◽  
Ruhua Ma ◽  
...  
Keyword(s):  
Sintering Temperature ◽  
Potassium Phosphate ◽  
High Level Waste ◽  
Radioactive Nuclide ◽  
Hydration Reaction ◽  
Sintering Process ◽  
Positive Role ◽  
Ceramic Structure ◽  
High Level

For the proposed novel procedure of immobilizing HLW with magnesium potassium phosphate cement (MKPC), Fe2O3 was added as a modifying agent to verify its effect on the solidification form and the immobilization of the radioactive nuclide. The results show that Fe2O3 is inert during the hydration reaction. It slows down the hydration reaction and lowers the heat release rate of the MKPC system, leading to a 3°C-5°C drop in the mixture temperature during hydration. Early comprehensive strength of Fe2O3 containing samples decreased slightly while the long-term strength remained unchanged. For the sintering process, Fe2O3 played a positive role, lowering the melting point and aiding the formation of ceramic structure. CsFe(PO4)2, or CsFePO4, was generated by sintering at 900°C. These products together with the ceramic structure and absorption benefit the immobilization of Cs+. The optimal sintering temperature for heat treatment is 900°C; it makes the solidification form a fired ceramic-like structure.

Thermal Stability of Glass with Imitators of Chloride High Level Radioactive Wastes

2018 ◽  
Vol 483 (4) ◽  
pp. 385-388
Author(s):  
S. Yudintsev ◽  
◽  
A. Shiryayev ◽  
◽  
◽  
...  
Keyword(s):  
Thermal Stability ◽  
Radioactive Wastes ◽  
High Level ◽  
Thermal Stability Of

scholarly journals The Influence of Zeolite (Sokyrnytsya Deposit) on the Physical and Chemical Resistance of a Magnesium Potassium Phosphate Compound for the Immobilization of High-Level Waste

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3421 ◽  
Author(s):  
Svetlana A. Kulikova ◽  
Sergey E. Vinokurov
Keyword(s):  
Compressive Strength ◽  
Hydrolytic Stability ◽  
Potassium Phosphate ◽  
High Level Waste ◽  
Leaching Rate ◽  
New Material ◽  
Hydrolytic Resistance ◽  
Main Component ◽  
High Level ◽  
Physical And Chemical

The manuscript presents the results of the development of new material for high-level waste (HLW) management: the magnesium potassium phosphate (MKP) compound. The possibility of using zeolite (Sokyrnytsya deposit) to increase the mechanical, thermal, and hydrolytic resistance of this compound with immobilized HLW was studied. The main component of the used natural zeolite is a mineral of the clinoptilolite–heulandite series, and quartz, microcline, and clay minerals (illite, sepiolite, and smectite) are present as impurities. The compressive strength of the compound, containing at least 4.2 wt % zeolite, is about 25 MPa. Compound containing 28.6 wt % zeolite retains high compressive strength (at least 9.0 MPa), even after heat treatment at 450 °C. The adding of zeolite to the composition of the compound increases its hydrolytic stability, while the leaching rate of the mobile nuclides 137Cs and 90Sr decreases up to one order of values. Differential leaching rate of radionuclides from the compound containing 28.6 wt % zeolite is 2.6 × 10−7 for 137Cs, 2.9 × 10−6 for 90Sr, 1.7 × 10−9 for 239Pu, and 2.9 × 10−9 g/(cm2∙day) for 241Am. Thus, the properties of the resulting compound correspond to the requirements for solidified HLW in Russia.

Thermally More Durable Electromechanical Films by POSS Nanomodification

2013 ◽  
Vol 538 ◽  
pp. 65-68 ◽  
Author(s):  
Mika Paajanen ◽  
Mikko Karttunen ◽  
Satu Kortet ◽  
Outi Härkki ◽  
Inka Orko
Keyword(s):  
Thermal Stability ◽  
Expansion Method ◽  
Gas Diffusion ◽  
Film Structure ◽  
Contact Charging ◽  
Cast Films ◽  
Gold Sputtering ◽  
High Level ◽  
Oligomeric Silsesquioxane ◽  
Thermal Stability Of

The thermal stability of polypropylene (PP) based cellular electromechanical films was improved by compounding PP with thermally more durable cyclo olefin copolymer (COC) and polyhedral oligomeric silsesquioxane (POSS) nanochemical. The cast films were biaxially oriented in laboratory scale and then expanded by a gas diffusion expansion method, which increased the pore size inside the cellular film structure and the thickness of the film. The cellular films were then electrostatically charged by a contact charging method and metallized by gold sputtering. The samples were aged at 85°C showing that the d33 signal decreased from the original value, but remained at high level; more than 120 pC/N even after two weeks of ageing.

The fixation of high-level wastes in glasses

1986 ◽  
Vol 319 (1545) ◽  
pp. 49-62 ◽  
Keyword(s):  
Borosilicate Glass ◽  
High Level Waste ◽  
Geological Repository ◽  
Important Barrier ◽  
Processing Wastes ◽  
Under Construction ◽  
High Level ◽  
Thermal Stability Of ◽  
Selection Of

A plant for the fixation of high-level wastes in borosilicate glass has been operating in France since 1978. A large plant is under construction in the U.S. for the fixation of defence high-level waste and plans for other glass fixation plants are well advanced at several sites around the world. Among the reasons for the selection of borosilicate glass as a fixation medium are the relative ease of processing wastes of variable composition by means of well established technology, and the long-term radiation and thermal stability of the glass. Well formulated glass also has sufficient resistance to the action of groundwater so that it can serve as an important barrier against the spread of radionuclides via groundwater in any forseeable situation. Research is continuing to quantify the reactions of waste glass in site-specific geological repository environments.

scholarly journals Thermal Stability of Nanosilica-Modified Poly(Vinyl Chloride)

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2057
Author(s):  
Jolanta Tomaszewska ◽  
Tomasz Sterzyński ◽  
Damian Walczak
Keyword(s):  
Thermal Stability ◽  
Scanning Calorimetry ◽  
Melt Flow Rate ◽  
Color Changes ◽  
Visual Color ◽  
High Level ◽  
Induced Changes ◽  
Processing Properties ◽  
Dehydrochlorination Reaction ◽  
Thermal Stability Of

The thermal stability of PVC with 1 wt % of spherical porous nanosilica, prepared by roll milling at processing time varied from 1 to 20 min, was investigated by means of visual color changes, Congo red, and thermogravimetric tests (TGA and DTG), as a function of rolling time and composition of PVC matrix. The melt flow rate (MFR) measurements were realized to identify the degradation-induced changes of processing properties. A high level of gelation of the PVC matrix for all samples was verified by DSC (differential scanning calorimetry). It was found that the addition of porous nanosilica to absorb a certain volume of HCl, produced by dehydrochlorination reaction, leads to an improvement of thermal stability, an effect observed in a form of minor color changes of the samples, lower evolution of gas hydrogen chloride, and slight changes of the MFR value. It was demonstrated that the TGA measurements are not sufficiently sensible to detect the degradation of PVC at the processing conditions, i.e., at the temperature equal to 220 °C and below this temperature.

scholarly journals Study on Structure and Properties of La2O3-Doped Basaltic Glasses for Immobilizing Simulated Lanthanides

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4709
Author(s):  
Qin Tong ◽  
Jichuan Huo ◽  
Xingquan Zhang ◽  
Zhu Cui ◽  
Yongchang Zhu
Keyword(s):  
Thermal Stability ◽  
Chemical Stability ◽  
Glass Network ◽  
Waste Form ◽  
High Level Waste ◽  
Basaltic Glass ◽  
Consistency Test ◽  
Simulated Waste ◽  
High Level ◽  
Simulated High Level Waste

The La2O3-doped basaltic glass simulated high-level waste form (HLW) was prepared by the solid-state melt method. The simulated waste La2O3 maximum loading and the doping effect on structure, thermal stability, leaching behavior, density, and hardness of basaltic glasses were studied. XRD and SEM results show that the simulated waste loading of La2O3 in basaltic glass can be up to ~46 wt.%, and apatite (CaLa4(SiO4)3O) precipitates when the content of La2O3 reaches 56 wt.%. Raman results indicate that the addition of La2O3 breaks the Si–O–Si bond of large-membered and four-membered, but the number of A13+ involved in the formation of the network increase. Low content of La2O3 can help to repair the glass network, but it destroys the network as above 26 wt.%. DSC results show the thermal stability of simulated waste forms first increases and then decreases with the increase of La2O3 content. With the increase of La2O3 content, the density of the simulated waste form increases, and the hardness decreases. The leaching chemical stability of samples was evaluated by the ASTM Product Consistency Test (PCT) Method, which show that all the samples have good chemical stability. The leaching rates of La and Fe are three orders of magnitude lower than those of the other elements. Among them, L36 has the best comprehensive leaching performance.

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