The Dissolution of Irradiated Fuel Under Hydrothermal Conditions

1981 ◽  
Vol 6 ◽  
Author(s):  
Lawrence H. Johnson ◽  
Henry H. Joling
Keyword(s):  
Experimental Studies ◽  
Fission Products ◽  
Redox Chemistry ◽  
Hydrothermal Conditions ◽  
Product Release ◽  
Reducing Conditions ◽  
Dissolution Behaviour ◽  
Low Ionic Strength ◽  
Kinetics Of ◽  
Irradiated Fuel

ABSTRACTUranium dioxide, the major component of irradiated CANDU fuel, shows good hydrothermal stability under the appropriate redox conditions. The thermodynamic stability of UO2 in low ionic strength granite groundwater at 150°C under oxidizing and reducing conditions is briefly reviewed in order to provide a basis for discussion of the results of irradiated fuel dissolution experiments. Fuel chemistry characteristics that influence the kinetics of fission product release are also discussed.Experimental studies demonstrate the influence of redox chemistry on irradiated fuel dissolution behaviour. Undero9 trongly reducing conditions, both uranium and 99Tc concentrations in solution decrease to the detection limit, whereas appreciable concentrations of both elements accumulate under oxidizing conditions. The release of some fission products, such as 90Sr and 137Cs, does not seem to be strongly affected by changes in redox chemistry. Under oxidizing conditions, the rate of 90Sr release to solution increases by a factor of ten to twenty between 25 and 150°C.These studies indicate the need for further work in certain areas, in particular on the relative amounts of important fission productsreleased by leaching versus matrix dissolution, and on the effect of the products of α–radiolysis of water on the dissolution of irradiated fuel.

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

Test facility for studying kinetics of release of gaseous radioactive fission products from irradiated materials

1974 ◽  
Vol 36 (1) ◽  
pp. 89-91
Author(s):  
D. M. Skorov ◽  
A. I. Dashkovskii ◽  
A. G. Zaluzhnyi ◽  
O. M. Storozhuk
Keyword(s):  
Fission Products ◽  
Test Facility ◽  
Kinetics Of

Kinetic model for calcium sulfate α-hemihydrate produced hydrothermally from gypsum formed by flue gas desulfurization

2015 ◽  
Vol 48 (3) ◽  
pp. 827-835 ◽  
Author(s):  
Mingliang Tang ◽  
Xuerun Li ◽  
Yusheng Shen ◽  
Xiaodong Shen
Keyword(s):  
Flue Gas ◽  
Calcium Sulfate ◽  
High Performance ◽  
Transformation Process ◽  
Flue Gas Desulfurization ◽  
Synthesis Process ◽  
Stable Phase ◽  
Hydrothermal Conditions ◽  
Simple Method ◽  
Kinetics Of

Modeling of the kinetics of the synthesis process for calcium sulfate α-hemihydrate from gypsum formed by flue gas desulfurization (FGD) is important to produce high-performance products with minimal costs and production cycles under hydrothermal conditions. In this study, a model was established by horizontally translating the obtained crystal size distribution (CSD) to the CSD of the stable phase during the transformation process. A simple method was used to obtain the nucleation and growth rates. A nonlinear optimization algorithm method was employed to determine the kinetic parameters. The model can be successfully used to analyze the transformation kinetics of FGD gypsum to α-hemihydrate in an isothermal batch crystallizer. The results showed that the transformation temperature and stirring speed exhibit a significant influence on the crystal growth and nucleation rates of α-hemihydrate, thus altering the transformation time and CSD of the final products. The characteristics obtained by the proposed model can potentially be used in the production of α-hemihydrate.

Kinetics of hypso anhydrites dissolution in water. Experimental studies

2019 ◽  
pp. 93-96
Author(s):  
A. L. Lebedev ◽  
I. V. Avilina
Keyword(s):  
Experimental Data ◽  
Experimental Study ◽  
Riccati Equation ◽  
Balance Equation ◽  
Experimental Studies ◽  
Common Ion ◽  
The Common ◽  
Common Ion Effect ◽  
Kinetics Of Dissolution ◽  
Kinetics Of

Experimental study of kinetics of dissolution of hypso anhydrites at 25 ᵒC made it possible to formulate model of the process in the form of a balance equation for the kinetics of dissolution of gypsum, anhydrite (first and second orders, respectively) and kinetics of precipitation of gypsum (second order). The processing of the experimental data were carried out on the basis of the solution of the Riccati equation. When taking into account the common-ion effect on the solubility of gypsum and anhydrite, the calculated values turned out to be more comparable with the experimental ones.

Kinetics study of spreading processes of epoxy binders on carbon cloth surface with metal coating

2021 ◽  
Vol 0 (3) ◽  
pp. 34-38
Author(s):  
D.E. Grechushkina ◽  
◽  
V.A. Nelyub ◽  
Keyword(s):  
Considerable Increase ◽  
Experimental Studies ◽  
Copper Coating ◽  
Metal Coating ◽  
Carbon Cloth ◽  
Kinetics Study ◽  
Carbon Tape ◽  
Epoxy Binders ◽  
Kinetics Of ◽  
Spreading Processes

The results of experimental studies of kinetics of spreading processes of epoxy binders on the surface of a carbon (cloth) tape depending on a reinforcement pattern are presented. A copper coating of 100 nm thickness was deposited on reinforced materials by magnetron sputtering. It has been found out that a metal coating on the surface of a carbon tape and cloth leads to a considerable increase in the rate of spreading processes only for the laying-out pattern 0°, when binder movement in capillaries is provided. The deposition of a copper coating on the surface of the carbon tape and cloth has considerably the bigger influence on kinetics of the spreading processes, increasing it by 35%.

Cooling of Fruit with Arbitrary Shape: Simulation Using Galerkin-Based Integral Method

2017 ◽  
Vol 10 ◽  
pp. 1-15
Author(s):  
P. Morais Pessôa ◽  
A.G. Barbosa de Lima ◽  
R. Swarnakar ◽  
J.P. Gomes ◽  
W.M.P. Barbosa de Lima
Keyword(s):  
Integral Method ◽  
Arbitrary Shape ◽  
Heat Conduction Equation ◽  
Low Cost ◽  
Experimental Studies ◽  
Volume Ratio ◽  
Transient Heat Conduction ◽  
Cooling Time ◽  
Time Required ◽  
Kinetics Of

Cooling has been used for the preservation of fresh produce such as fruit and vegetables due to its low cost and high effectiveness in maintaining the product quality. Recently, several researchers have conducted theoretical and experimental studies for obtaining the kinetics of cooling and cooling time for fruits with different geometries. Present work, therefore, aims to simulate the cooling of fruits with particular reference to banana, orange, strawberry and Tahiti lemon. The transient heat conduction equation and its analytical solution using Galerkin based integral method are presented. It has been found that the strawberry has lower dimensionless cooling time compared with time required to cool other fruits, which is due to its higher surface area/volume ratio value. In orange and lemon the temperature distribution was found to be homogeneous in the angular direction, while in banana and strawberry it was two-dimensional due to shape of the fruits.

The Effect of Waste Package Components on Radionuclides Released from Spent Fuel Under Hydrothermal Conditions

1987 ◽  
Vol 112 ◽  
Author(s):  
Shirley A. Rawson ◽  
William L. Neal ◽  
James R. Burnell
Keyword(s):  
Low Carbon Steel ◽  
Fission Products ◽  
Nuclear Waste Repository ◽  
Low Carbon ◽  
Spent Fuel ◽  
Hydrothermal Conditions ◽  
Waste Package ◽  
Dissolved Species ◽  
Radionuclide Release ◽  
Time Invariant

AbstractThe Basalt Waste Isolation Project has conducted a series of hydrothermal experiments to characterize waste/barrier/rock interactions as a part of its study of the Columbia River basalts as a potential medium for a nuclear waste repository. Hydrothermal tests of 3–15 months duration were performed with light water reactor spent fuel and simulated groundwater, in combination with candidate container materials (low-carbon steel or copper) and/or basalt, in order to evaluate the effect of waste package materials on spent fuel radionuclide release behavior. Solutions were filtered through 400 and 1.8 nm filters to distinguish colloidal from dissolved species. In all experiments, 14C, 129I, and 137Cs occurred only as dissolved species, whereas the actinides occurred in 400 nm filtrates primarily as spent fuel particles. Actinide concentrations in 1.8 nm filtrates were below detection in steel-bearing experiments. In the system spent fuel + copper, apparent time-invariant concentrations of 14C and 137Cs were obtained, but in the spent fuel + steel system, the concentrations of 14C and 137Cs increased gradually throughout the experiments. In experiments containing basalt or steel + basalt, 137Cs concentrations decreased with time. In tests with copper + basalt, 14C and 129I concentrations attained time-invariant values and 137Cs concentrations decreased. Concentrations for the actinides and fission products measured in these experiments were below those calculated from Federal regulations governing radionuclide release.

scholarly journals Numerical Simulation of Decontamination of Airborne Fission Products during In-Vessel Release Phase by Containment Spray

2018 ◽  
Vol 2018 ◽  
pp. 1-19
Author(s):  
Khurram Mehboob
Keyword(s):  
Droplet Size ◽  
Failure Time ◽  
Ph Value ◽  
Removal Rate ◽  
Droplet Diameter ◽  
Fission Products ◽  
Product Release ◽  
Spray System ◽  
Spray Solution ◽  
Proposed Model

The containment spray system (CSS) has a significant role in limiting the risk of radioactive exposure to the environment. In this work, the optimal droplet size and pH value of spray water to prevent the fission product release have been evaluated to improve the performance of the spray system during in-vessel release phase. A semikinetic model has been developed and implemented in MATLAB. The sensitivity and removal rate of airborne isotopes with the spray system have been simulated versus the spray activation and failure time, droplet size, and pH value. The alkaline (Na2S2O3) spray solution and spray water with pH 9.5 have similar scrubbing properties for iodine. However, the removal rate from the CSS has been found to be an approximately inverse square of droplet diameter (1/d2) for Na2S2O3 and higher pH of spray water. The numerical results showed that 450 μm–850 μm droplet with 9.5 pH and higher or the alkaline (Na2S2O3) solution with 0.2 m3/s–0.35 m3/s flow rate is optimal for effective scrubbing of in-containment fission products. The proposed model has been validated with TOSQAN experimental data.

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