Instant release fractions for 14C, 60Co, and 125Sb from irradiated Zircaloy oxide film

MRS Advances ◽  
2019 ◽  
Vol 5 (1-2) ◽  
pp. 9-17
Author(s):  
Tomofumi Sakuragi ◽  
Yu Yamashita
Keyword(s):  
Leaching Test ◽  
Spent Fuel ◽  
Volatile Species ◽  
Solution Ph ◽  
Ultrasonic Bath ◽  
Potential Source ◽  
Maximum Value ◽  
Activity Ratios ◽  
Naoh Solution ◽  
Instantaneous Release

AbstractThe oxide films formed on spent fuel claddings are regarded as a potential source of the instantaneous release of radionuclides, such as 14C, after waste disposal. We investigated the instant release fraction using the irradiated oxide exfoliated from a Zircaloy-2 water rod, whose bundle burnup was 53.0 GWd/MTU. We performed a rapid leaching test in a dilute NaOH solution (pH of 12.5) for 10 min in an ultrasonic bath to ensure the release of radionuclides. The activity ratios of the leached amount to the total amount for 14C, 60Co, and 125Sb were extremely low at approximately 10-4 to 10-3, among which the maximum value was 2.65 × 10-3 for 125Sb. These ratios were higher than that predicted from the thermodynamic solubility of ZrO2, i.e., less than 10-6. However, given the low ratios, it is too conservative to regard the inventory of all radionuclides in the Zircaloy oxide as instantaneous release. A small part of the released 14C was found as volatile species.

scholarly journals Characteristics of Solidified Products Containing Radioactive Molten Salt Waste

2007 ◽  
Author(s):  
In-Tae Kim ◽  
Hwan-Seo Park ◽  
Yong-Zun Cho ◽  
Kwang-Wook Kim ◽  
Seong-Won Park ◽  
...  
Keyword(s):  
Molten Salt ◽  
Material System ◽  
Leaching Test ◽  
Spent Fuel ◽  
Micro Hardness ◽  
Chemical Route ◽  
Rich Phase ◽  
Stable Chemical ◽  
Semi Empirical

For a treatment of molten salt wastes generated from a pyroprocessing of oxide spent fuel, we had suggested a stable chemical route, named GRSS (Gel-Route Stabilization & Solidification), and a subsequent consolidation method. By using this method, a series of monolithic wasteforms with different conditions were fabricated, and then their physicochemical properties were investigated. A simulated salt containing 90wt% LiCl, 6.8wt% CsCl, and 3.2wt% SrCl2 was treated with a gel-forming material system, Si/Al/P = 0.4/0.4/0.2 and 0.35/0.35/0.3, and the gel-products were treated at 1100C° after mixing with borosilicate glass powder, where the salt loadings were about 16∼20wt%. The solidified products had a density of 2.3∼2.35g/cm3, a micro-hardness of 4.69∼4.72GPa, a glass transition temperature of 528∼537C°, and a thermal expansion coefficient of 1.65×10−7∼3.38×10−5/C°. Leaching results by the PCT-A method revealed leached rates, 10−3∼10−2g/m2day and 10−4∼10−3g/m2day for Cs and Sr, respectively. From the long-term ISO leaching test, the 900day-leached fraction of Cs and Sr predicted by a semi-empirical model were 0.89% and 0.39%. The leaching behaviors indicated that Cs would be immobilized into a Si-rich phase while Sr would be in a P-rich phase. The experimental results revealed that the GRSS method could be an alternative method for a solidification of radioactive molten salt wastes.

scholarly journals Preparation of Nanocellulose Aerogel from the Poplar (Populus tomentosa) Catkin Fiber

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 749 ◽  
Author(s):  
Wu ◽  
Sun ◽  
Wu ◽  
Shi ◽  
Chen ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Honeycomb Structure ◽  
Populus Tomentosa ◽  
Raw Material ◽  
Sodium Chlorite ◽  
Maximum Value ◽  
Ultrasonic Time ◽  
Naoh Solution ◽  
The Difference

: The effects of chemical pretreatment on the purification of poplar (Populus tomentosa) catkin fiber and the effect of ultrasonic time for the microfibrillarization of poplar catkin fiber (PCF) were studied. The nanocellulose aerogels were prepared by freeze drying the cellulose solutions. The density, porosity, micro morphology, thermal stability and mechanical properties of the aerogels were analyzed. It was found that the dewaxing time of PCF is shorter than that of unsonicated nanocellulose. After the treatment of 0.5 wt% sodium chlorite for 2 h, the lignin of PCF was removed. After the chemical purification, the PCF was treated with 2 and 5 wt% NaOH solution and ultrasonicated for 5 and 10 min, respectively. When the ultrasonic time was 10 min, the diameter of the nanocellulose was 20-25 nm. When the ultrasonic time was 5 min, the aerogels with porous honeycomb structure can be prepared by using the nanocellulose sol of PCF as raw material. The density of the aerogels was only 0.3-0.4 mg/cm3 and the porosities of the aerogels were all larger than 99%. The difference between the pyrolysis temperature of aerogels was small, the elastic modulus of aerogels was 30–52 kPa, and the compressive strength was 22–27 kPa. With the increase of the concentration of NaOH solution (5 wt%) and ultrasonic time (10 min), the elastic modulus of aerogels increased gradually and reached the maximum value of 52 kPa, while the compressive strength reached the maximum value of 27 kPa when the PCF being treated in 5 wt% NaOH solution and was ultrasonicated for 5 min.

scholarly journals ADSORPTION OF CEFIXIME TRIHYDRATE ONTO CHITOSAN 10B FROM AQUEOUS SOLUTION: KINETIC, EQUILIBRIUM AND THERMODYNAMIC STUDIES

2021 ◽  
Vol 55 (7-8) ◽  
pp. 771-784
Author(s):  
GAZI SALAH UDDIN ◽  
SOMA SAHA ◽  
SUBARNA KARMAKER ◽  
TAPAN KUMAR SAHA
Keyword(s):  
Aqueous Solution ◽  
Aqueous Medium ◽  
Significant Loss ◽  
Solution Ph ◽  
Adsorption Ability ◽  
Naoh Solution ◽  
Pseudo Second Order ◽  
Solution Kinetic ◽  
Kinetic Equilibrium ◽  
Operational Aspects

An efficient and biodegradable adsorbent chitosan 10B was used to eliminate cefixime trihydrate from aqueous solution. The kinetic behavior of cefixime trihydrate adsorption onto chitosan 10B was studied in aqueous medium, from various operational aspects, such as contact time, solution pH, antibiotic concentrations, and temperatures. Cefixime adsorption onto chitosan 10B was confirmed by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). The antibiotic adsorption kinetics obeyed a pseudo-second-order model rather than pseudo-first-order and Elovich kinetic models. The best illustration of antibiotic adsorption equilibrium was made by the Langmuir model, with the highest adsorption ability qm: 37.04 μmol/g at 298 K. The activation energy (Ea) of the present adsorption system was computed to be 44.18 kJ/mol. The values of activation (ΔG‡, ΔH‡ and ΔS‡) and thermodynamic (ΔG, ΔH and ΔS) parameters confirmed that the cefixime trihydrate adsorption onto chitosan 10B in aqueous medium is an exothermic physisorption process. Cefixime desorption from antibiotic-loaded chitosan 10B was performed in 0.1 M NaOH solution and the recycled adsorbent was utilized for a second time without significant loss of its adsorption capacity.

Removal of As, Cr and Cd by Absorptive Filtration

2013 ◽  
Vol 6 (1) ◽  
pp. 73-80 ◽  
Keyword(s):  
Environmental Protection Agency ◽  
Batch Adsorption ◽  
Solution Ph ◽  
Sand Filters ◽  
Bench Scale ◽  
Sand Surface ◽  
Iron Solution ◽  
The Us ◽  
Naoh Solution ◽  
In Series

The US Environmental Protection Agency (USEPA) recently introduced more stringent arsenic regulations by lowering the maximum contaminant level (MCL) to 10 ìg l-1 (ppb) arsenic in drinking water. During the present study, an iron solution injection sand filtration process was designed and tested to selectively remove arsenic (As(V)), chromate (Cr(VI)) and cadmium (Cd(II)) from aqueous solutions down to trace level. Bench scale sand columns with a chemical feeding system were used to conduct the filtration study. The filtration results demonstrate that As(V) could be removed by ferric solution-treated sand filters from 2,000 ìg l-1 (ppb) down to less than 5 ìg l-1 (ppb) using two sand filters connected in series (two stage filtration). During the filtration, ferric concentrations in the first and second filters were maintained at 5 and 2 ppm, respectively, through a continuous injection scheme. Bench scale filtration results suggest that Cr(VI) could also be effectively removed by injection of ferrous solution into the sand columns. Similar ferric treatment of the sand columns also significantly increased Cd(II) removal. Batch adsorption experimental results suggest that when solution pH is lower than 8, arsenate can be removed by iron-treated sand. Arsenate-saturated sand can be regenerated using a high pH (pH > 12) solution. Scanning Electron Microscope (SEM) and energy dispersive x-ray (EDX) studies suggest that very little amount of Fe on the sand surface was dissolved when the sand was regenerated using a dilute NaOH solution (pH = 13).

Fabrication of Composites from Apatite and Chemically Synthesized Collagen

2012 ◽  
Vol 529-530 ◽  
pp. 426-429 ◽  
Author(s):  
Toshiki Miyazaki ◽  
Akimasa Kuramoto
Keyword(s):  
Triple Helix ◽  
Single Phase ◽  
Solution Treatment ◽  
Bone Substitutes ◽  
Ion Concentration ◽  
Apatite Formation ◽  
Polyglutamic Acid ◽  
Solution Ph ◽  
Fabrication Procedure ◽  
Naoh Solution

Chemically synthesized collagen with triple helix structure similar to natural collagen has been developed as a safe biomaterial. If the chemically synthesized collagen is deposited with apatite, they are expected for novel bone substitutes having bioactivity and bioresorbability. Although apatite formation on the chemically synthesized collagen has been examined, highly supersaturated condition such as 1.5SBF with ion concentration 1.5 times those of simulated body fluid (SBF) is needed to achieve apatite formation. In the present study, we intended acceleration on the apatite formation on the chemically synthesized collagen by immobilization with polyglutamic acid (PGA). PGA is known as biodegradable and biocompatible polypeptide having excellent apatite-forming ability. We examined effects of the immobilization procedure on mineralization behavior in SBF. At first, PGA was immobilized on porous sponges of chemically synthesized collagen in aqueous solutions containing PGA and CaCl2. As a result, not only apatite but also calcite-type CaCO3 was deposited on the specimens in SBF. The calcite formation was occurred during the treatment with PGA solution. pH of the solution was adjusted to 7 by NaOH solution in order to avoid dissolution of the collagen. During this procedure, Ca (OH)2 would be precipitated by locally increase in pH of the solution and converted into the calcite. When the PGA solution treatment was shortened so as to prevent the calcite formation, single phase of the apatite was formed in SBF. The present results indicate that crystalline phase deposited on the chemically synthesized collagen can be controlled by fabrication procedure, and provide fundamental design of composites containing apatite and chemically synthesized collagen useful for bone regeneration.

scholarly journals Characterization, Dissolution, and Solubility of Lead Hydroxypyromorphite [Pb5(PO4)3OH] at 25–45°C

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yinian Zhu ◽  
Zongqiang Zhu ◽  
Xin Zhao ◽  
Yanpeng Liang ◽  
Yanhua Huang
Keyword(s):  
Molar Ratio ◽  
Stoichiometric Ratio ◽  
Ultrapure Water ◽  
Solution Ph ◽  
Free Energy Of Formation ◽  
Initial Ph ◽  
Naoh Solution ◽  
Water Ph ◽  
Ft Ir ◽  
Sem Analyses

Dissolution of the hydroxypyromorphite [lead hydroxyapatite, Pb5(PO4)3OH] in HNO3solution (pH = 2.00), ultrapure water (pH = 5.60), and NaOH solution (pH = 9.00) was experimentally studied at 25°C, 35°C, and 45°C. The XRD, FT-IR, and FE-SEM analyses indicated that the hydroxypyromorphite solids were observed to have indistinguishable change during dissolution. For the hydroxypyromorphite dissolution in aqueous acidic media at initial pH 2.00 and 25°C, the aqueous phosphate concentrations rose quickly and reached the peak values after 1 h dissolution, while the aqueous lead concentrations rose slowly and reached the peak values after 1440 h. The solution Pb/P molar ratio increased constantly from 1.10 to 1.65 near the stoichiometric ratio of 1.67 to 209.85~597.72 and then decreased to 74.76~237.26 for the dissolution at initial pH 2.00 and 25°C~45°C. The averageKspvalues for Pb5(PO4)3OH were determined to be 10−80.77(10−80.57−10−80.96) at 25°C, 10−80.65(10−80.38−10−80.99) at 35°C, and 10−79.96(10−79.38−10−80.71) at 45°C. From the obtained solubility data for the dissolution at initial pH 2.00 and 25°C, the Gibbs free energy of formation [ΔGfo] for Pb5(PO4)3OH was calculated to be −3796.71 kJ/mol (−3795.55~−3797.78 kJ/mol).

Decomposition Characteristics of Hydrogen Peroxide in Sodium Hydroxide Solution

2012 ◽  
Vol 610-613 ◽  
pp. 359-362 ◽  
Author(s):  
Tian Xiang Guo ◽  
Yi Zhao ◽  
Shuang Chen Ma ◽  
Song Tao Liu
Keyword(s):  
Hydrogen Peroxide ◽  
Sodium Hydroxide ◽  
Reaction Rate ◽  
Sodium Hydroxide Solution ◽  
Decomposition Temperature ◽  
Reaction Rate Constant ◽  
Reactive Intermediate ◽  
Solution Ph ◽  
H2o2 Decomposition ◽  
Naoh Solution

In order to spread more applications, decomposition characteristics of hydrogen peroxide (H2O2) in sodium hydroxide (NaOH) solution were investigated in this paper. Research results indicate that the attack of charged particles such as OH- and HO2- leads to H2O2 decomposition. HO2¬- is vital reactive intermediate, which was mainly from neutral reaction of H2O2 with NaOH. The decomposition is considered as pseudo-two-order kinetics, and the reaction rate constant depended on decomposition temperature and solution pH. The apparent average activation energy is 51.92 kJ•mol-1 when the initial NaOH concentration is 1mol•L-1 and solution pH is 10.5.

Study on the Reduction of Oolitic Hematite Ores in N2-CO Atmosphere

2014 ◽  
Vol 968 ◽  
pp. 198-201
Author(s):  
Guang Long Jin ◽  
Jin Zhu Zhang ◽  
Ben Jun Xu ◽  
Song Yang
Keyword(s):  
Carbon Monoxide ◽  
Steel Industry ◽  
Iron Ore ◽  
Direct Reduction ◽  
Iron And Steel Industry ◽  
Iron And Steel ◽  
Reduction Time ◽  
Potential Source ◽  
Maximum Value ◽  
Metallization Rate

The oolitic hematite will be a potential source of raw iron ore for the Chinese iron and steel industry. Up to now, the oolitic hematite have hardly been utilized effectively by any single traditional technology. The direct reduction may be a practical technology for the exploitation of oolitic hematite. The results show that the metallization rate of the HeZhang oolitic hematite increases with both the partial pressure of CO increase and the reduction time lasted, and the maximum value of the metallization rate is obtained at 35% carbon monoxide in the N2-CO atmosphere and 4h reduction time at 1050°C with 10% calcium oxide in the oolitic hematite. The diffusion may be the primary factor controlled the metallization rate in the later stage of reduction.

Release of 108Ag from Irradiated PWR Control Rod Absorbers under Deep Repository Conditions

2015 ◽  
Vol 1744 ◽  
pp. 217-222
Author(s):  
O. Roth ◽  
M. Granfors ◽  
A. Puranen ◽  
K. Spahiu
Keyword(s):  
Nuclear Fuel ◽  
Source Term ◽  
Spent Nuclear Fuel ◽  
Nuclear Reactors ◽  
Reactor Irradiation ◽  
Spent Fuel ◽  
Control Rod ◽  
Potential Source ◽  
Absorber Material ◽  
Control Rods

ABSTRACTIn a future Swedish deep repository for spent nuclear fuel, irradiated control rods from PWR nuclear reactors are planned to be stored together with the spent fuel. The control rod absorber consists of an 80% Ag, 5% Cd, 15% In alloy with a steel cladding. Upon in-reactor irradiation 108Ag is produced by neutron capture. Release of 108Ag has been identified as a potential source term for release of radioactive substances from the deep repository.Under reducing deep repository conditions, the Ag corrosion rate is however expected to be low which would imply that the release rate of 108Ag should be low under these conditions. The aim of this study is to investigate the dissolution of PWR control rod absorber material under conditions relevant to a future deep repository for spent nuclear fuel. The experiments include tests using irradiated control rod absorber material from Ringhals 2, Sweden. Furthermore, un-irradiated control rod absorber alloy has been tested for comparison. The experiments indicate that the release of Ag from the alloy when exposed to water is strongly dependent on the redox conditions. Under aerated conditions Ag is released at a significant rate whereas no release could be measured after 133 days during leaching under H2.

Experimental Study on Sandstone Freezing-Thawing Damage Properties under Condition of Water Chemistry

2014 ◽  
Vol 608-609 ◽  
pp. 726-731 ◽  
Author(s):  
Hong Wei Deng ◽  
Chun Fang Dong ◽  
Jie Lin Li ◽  
Ke Ping Zhou ◽  
Wei Gang Tian ◽  
...  
Keyword(s):  
Mass Fraction ◽  
Nacl Solution ◽  
Quality Change ◽  
Three Solutions ◽  
Solution Ph ◽  
Splitting Test ◽  
Naoh Solution ◽  
Chemical Solutions ◽  
Brazilian Splitting ◽  
Physical Mechanics

For the purpose of researching the freezing-thawing cycle pHysical mechanics properties of sandstone in various chemical solutions, taking the red sandstones from Shandong as the example, freezing-thawing cycles experiments under the condition of H2SO4 solution (pH≈1.5), NaOH solution (pH≈12.5), NaCl solution (pH≈7, mass fraction is 4%) and water were conducted. The nuclear magnetic resonance (NMR) technique was used to test the porosity of rock samples after freezing-thawing cycles. Brazilian splitting test was also conducted to test the samples with different times of freezing-thawing cycles and soaking solutions. Results show that the quality change of samples in various solutions is different. The mass of sample in water increased, however, the mass change of the sample in other three solutions showed a firstly increasing and then decreasing tendency. The porosity distribution in rock changed obviously after different time’s freezing-thawing cycles. After 30 times freezing-thawing cycles, the porosity in H2SO4 solution, NaOH solution, NaCl solution and water has increased by 151.1%, 85.443%, 39.388%, and 17.976% respectively. With the increase of freezing-thawing cycle’s times, tensile strength of the rock reduced, but the damage properties were different in various solutions. The research can provide some mechanical parameters basis to physical mechanics properties of sandstones.

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