Thermodynamic Simulation of Heating of Radioactive Graphite in Argon Atmosphere

Self-fluxing nickel or cobalt-based alloys that use boron, phosphorus or silicon, as melting point depressants and fluxing agents are thermodynamic simulation of self-fluxing materials Ni-0.5C-15Cr-3.2Si-2B (PGSR-2) and Ni-1C-17Cr-4.1Si-3.6B (PGSR-4) was performed. As the software for simulation of phase and chemical equilibrium the TERRA software package was used. The simulation was carried out in the temperature range 300–3000 K at a total pressure P = 105 Pa in an argon atmosphere. The temperature dependences of the equilibrium composition and thermodynamic characteristics (enthalpy, entropy, and Gibbs energy) of the alloys of the investigated systems were calculated. It is shown that Ni, Cr, C, Ni3B, Ni2B, NiB, Ni2Si, NiSi, CrB, CrSi can be formed in the condensed phase under equilibrium heating of PGSR-2. When PGSR-4 is heated in the condensed phase, along with the above components, Cr5B3, CrB2 and Cr3C2 compounds can be formed. The temperature dependences of the thermodynamic characteristics of the systems studied have kinks that can be explained by phase transformations.

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Thermodynamic simulation of the oxidation of radioactive graphite in the Na2CO3–K2CO3–NiO and Na2CO3–K2CO3–CuO melts

Russian Metallurgy (Metally) ◽

10.1134/s0036029517020045 ◽

2017 ◽

Vol 2017 (2) ◽

pp. 136-145 ◽

Cited By ~ 2

Author(s):

N. M. Barbin ◽

M. R. Shavaleev ◽

D. I. Terent’ev ◽

S. G. Alekseev

Keyword(s):

Thermodynamic Simulation ◽

Radioactive Graphite

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Modeling of Radioactive Graphite Oxidation in Molten Salts: Computer Experiment

MRS Proceedings ◽

10.1557/proc-1193-359 ◽

2009 ◽

Vol 1193 ◽

Cited By ~ 2

Author(s):

Nikolai M. Barbin ◽

Dmitri I. Terentiev ◽

Sergei G. Alekseyev ◽

Marat A. Tuktarov ◽

A. A. Romenkov

Keyword(s):

Nuclear Reactors ◽

Thermodynamic Simulation ◽

Computer Experiment ◽

Chemical Oxidation ◽

Chemical Transformations ◽

Radioactive Elements ◽

Radioactive Graphite ◽

Reactor Graphite ◽

Graphite Oxidation ◽

Salt Melts

AbstractGraphite is used as the neutron moderator and reflector in many nuclear reactors. Obsolete graphite nuclear reactors are put out of operation, leading to formation of a large quantity of radioactive graphite waste.It is proposed that irradiated reactor graphite is processed by high-temperature chemical oxidation in salt melts with an oxidant, which is part of the salt melt, leading to formation of exhaust gases: gaseous compounds of carbon and oxygen (CO2 and CO).This study deals with carbon oxidation and physical-chemical transformations of radioactive elements during the interaction between graphite waste of the atomic power industry and salt melts. The method of thermodynamic simulation is used. The carbon melt decreases the transfer of radionuclides to the gaseous phase as compared to incineration of graphite in the atmosphere.

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Thermodynamic modeling of the heating of radioactive graphite in an argon atmosphere

Теплофизика высоких температур ◽

10.31857/s004036440002718-3 ◽

2018 ◽

Vol 56 (5) ◽

pp. 751-763

Author(s):

N. Barbin ◽

◽

T. Kolbin ◽

D. Terentyev ◽

S. Alekseev ◽

...

Keyword(s):

Thermodynamic Modeling ◽

Argon Atmosphere ◽

Radioactive Graphite

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The effect of small additions of Cu on precipitation in Al-Mg-Si alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100135812 ◽

1990 ◽

Vol 48 (2) ◽

pp. 442-443

Author(s):

M. Tamizifar ◽

G. Cliff ◽

R.W. Devenish ◽

G.W. Lorimer

Keyword(s):

Electron Microscopy ◽

Analytical Electron Microscopy ◽

Scanning Transmission Electron Microscope ◽

Argon Atmosphere ◽

Age Hardening ◽

X Ray ◽

Transmission Electron ◽

Heat Treated ◽

Analytical Electron ◽

Scanning Transmission

Small additions of copper, <1 wt%, have a pronounced effect on the ageing response of Al-Mg-Si alloys. The object of the present investigation was to study the effect of additions of copper up to 0.5 wt% on the ageing response of a series of Al-Mg-Si alloys and to use high resolution analytical electron microscopy to determine the composition of the age hardening precipitates.The composition of the alloys investigated is given in Table 1. The alloys were heat treated in an argon atmosphere for 30m, water quenched and immediately aged either at 180°C for 15 h or given a duplex treatment of 180°C for 15 h followed by 350°C for 2 h2. The double-ageing treatment was similar to that carried out by Dumolt et al. Analyses of the precipitation were carried out with a HB 501 Scanning Transmission Electron Microscope. X-ray peak integrals were converted into weight fractions using the ratio technique of Cliff and Lorimer.

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The solubility of calcium carbonate in green liquor handling systems

TAPPI Journal ◽

10.32964/tj18.10.595 ◽

2019 ◽

Vol 18 (10) ◽

pp. 595-602

Author(s):

ALISHA GIGLIO ◽

VLADIMIROS G. PAPANGELAKIS ◽

HONGHI TRAN

Keyword(s):

Calcium Carbonate ◽

Systematic Study ◽

Kraft Pulp ◽

Thermodynamic Simulation ◽

Solubility Data ◽

Pulp Mills ◽

Persistent Problem ◽

Green Liquor ◽

Kraft Pulp Mills ◽

Salt Systems

The formation of hard calcite (CaCO3) scale in green liquor handling systems is a persistent problem in many kraft pulp mills. CaCO3 precipitates when its concentration in the green liquor exceeds its solubility. While the solubility of CaCO3 in water is well known, it is not so in the highly alkaline green liquor environment. A systematic study was conducted to determine the solubility of CaCO3 in green liquor as a function of temperature, total titratable alkali (TTA), causticity, and sulfidity. The results show that the solubility increases with increased temperature, increased TTA, decreased causticity, and decreased sulfidity. The new solubility data was incorporated into OLI (a thermodynamic simulation program for aqueous salt systems) to generate a series of CaCO3 solubility curves for various green liquor conditions. The results help explain how calcite scale forms in green liquor handling systems.

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Thermodynamic Simulation of a Hybrid Brayton Thermosolar Plant

Renewable Energy and Power Quality Journal ◽

10.24084/repqj14.253 ◽

2016 ◽

pp. 157-161

Author(s):

R.P. Merchan ◽

M.J. Santos ◽

A. Medina ◽

A. Calvo

Keyword(s):

Thermodynamic Simulation

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Effects of Ultrasounds on Neat nitrobenzene

Revista de Chimie ◽

10.37358/rc.19.8.7492 ◽

2019 ◽

Vol 70 (8) ◽

pp. 3085-3088

Author(s):

Carmen Eugenia Stavarache ◽

Yasuaki Maeda ◽

Mircea Vinatoru

Keyword(s):

Nitro Group ◽

Radical Cation ◽

Reaction Mechanisms ◽

Diphenyl Ether ◽

Argon Atmosphere ◽

Phenyl Radical ◽

Dissolved Gas ◽

Decomposition Products ◽

Oxygenated Compounds ◽

Phenyl Cation

Neat nitrobenzene was continuously irradiated at two ultrasonic frequencies: 40 and 200 kHz, under air and argon atmosphere, respectively. Samples taken at intervals of 1, 5, 10 and 24 h were analyzed by GC-MS and decomposition products were identified. Possible reaction mechanisms are discussed. Presence of air as dissolved gas leads to oxygenated compounds such as 1,4-benzoquinone, 2,4-dinitrophenol, m-dinitrobenzene while argon inhibits the decomposition of nitrobenzene, especially at sonication times under 5 h. Based on the nature of the compounds identified we advanced a mechanism, involving a divergent splitting of unstable radical cation of NB in air and argon respectively. Thus, under air, the phenyl cation formation is preferred leading to 1,4-benzoquinone nitro-biphenyls and dinitrobenzene, while under argon, the phenyl radical formation seems to be favored, leading to phenol and diphenyl ether. The oxygenated compounds detected under argon clearly are a consequence of the nitro group splitting.

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