Nuclear Waste Immobilization in Cement-Based Materials: Overview of French Studies

1989 ◽  
Vol 176 ◽  
Author(s):  
Rosemarie Atabek ◽  
Pascal Bouniol ◽  
Eliane Revertegat ◽  
Jean Oliver ◽  
Philippe Gegout ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Blended Cement ◽  
Chemical Degradation ◽  
Concrete Durability ◽  
Burial Site ◽  
French Studies ◽  
Degradation Reactions ◽  
Waste Immobilization ◽  
Materials Used ◽  
Nuclear Waste Immobilization

ABSTRACTAn overview of the different problems to be solved for waste form disposal in a shallow-land burial site is presented. Examples of cementbased materials used to immobilize concentrates are given in relation to cement chemistry. Experimental studies, undertaken to assess concrete durability, obviously indicate that pH is the starting parameter of chemical degradation reactions. It is found that blended cement (CLC) has a better cesium retention ability and a stronger resistance to chloride and sulfate attack than Portland cement.

Can Soy Methyl Esters Improve Concrete Pavement Joint Durability?

2012 ◽  
Vol 2290 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Michael Golias ◽  
Javier Castro ◽  
Alva Peled ◽  
Tommy Nantung ◽  
Bernard Tao ◽  
...  
Keyword(s):  
Methyl Esters ◽  
Field Trials ◽  
Chemical Degradation ◽  
Maintenance Cost ◽  
Concrete Durability ◽  
Concrete Pavements ◽  
Freeze Thaw ◽  
Fluid Saturation ◽  
Soy Methyl Ester ◽  
Term Performance

Although many concrete pavements provide excellent long-term performance, some pavements (primarily in the Midwest) have shown premature deterioration at the joints. This premature deterioration is a concern because such deterioration can shorten the life of pavements that are otherwise functioning well. Previous work has hypothesized that these joints may be susceptible to preferential fluid saturation, which can lead to freeze–thaw damage or chemical degradation. This work examines the use of soy methyl ester–polystyrene (SME-PS) blends as a method to reduce the rate of fluid ingress into the pore system of the concrete and thereby make the concrete more resistant to deterioration. SME-PS is derived from soybeans and has demonstrated an ability to reduce fluid absorption in concrete when used as a topical treatment. A series of experiments was developed to evaluate the effectiveness of various dosage rates of SME-PS for increasing concrete durability at pavement joints. The experiments show that SME-PS reduces fluid ingress, salt ingress, and the potential for freeze–thaw damage. As a result of the positive experimental results, the Indiana Department of Transportation is conducting field trials that use SME-PS on concrete pavements that are beginning to show signs of premature deterioration with the expectation that SME-PS will extend the life of the joints and thereby reduce maintenance cost and extend the life of concrete pavements.

scholarly journals STUDY OF THE EFFECTIVENESS OF VIBRATION ISOLATION OF UNCONVENTIONAL TOROIDAL ROPE VIBRATION ISOLATORS IN DIESEL UNITS VIBRATION ISOLATION SYSTEM

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 110-114
Author(s):  
Minas Minasyan ◽  
Armen Minasyan ◽  
Aung Thant
Keyword(s):  
Power Plants ◽  
Vibration Isolation ◽  
Steel Wire ◽  
Experimental Studies ◽  
Wire Rope ◽  
Diesel Generator ◽  
Isolation System ◽  
Vibration Isolators ◽  
Before And After ◽  
Materials Used

The paper notes that the structure of the wire rope is one of the most suitable materials used as a fire-resistant elastic element of vibration-insulating structures and fasteners (vibration isolators). To solve the problems of vibration isolation of marine diesel power plants in the framework of development and improvement of the shock absorption system, the original patented elastic supports with elastic elements made of steel wire rope in the form of a torus are presented. When commercially available vibration isolators do not meet the relevant requirements of vibration protection of a particular object, the solution to the existing problem can be achieved by using the proposed wire rope vibration isolators. The technical results of the original patented inventions are: - equal stiffness in the horizontal plane - ensuring the reliability and high vibration efficiency of protection against impacts and shocks. The proposed designs of vibration isolators are easy (technological in manufacturing) to manufacture and assemble, reliable and durable - the service life is 10 years or more. Vibration efficiency is confirmed by the vibration acceleration spectra before and after the vibration isolator of the damping system of the ship diesel-generator DGA-500 and the diesel unit with a 2H 8.5/11 engine and water brake on a common sub-frame. The three-year trial life of the DGA-500 and experimental studies on a diesel unit with a 2H 8.5/11 engine and water brake on a common sub-frame confirms their efficiency and effectiveness.

Nuclear Waste Immobilization by Vitrification in a Cold Crucible Melter: 3D Magnetic Model of a Melter

2008 ◽  
Vol 1107 ◽  
Author(s):  
A. Bonnetier
Keyword(s):  
Hydraulic Properties ◽  
Cold Crucible ◽  
Nuclear Facilities ◽  
Electromagnetic Design ◽  
Waste Vitrification ◽  
3D Geometry ◽  
Waste Immobilization ◽  
Magnetic Model ◽  
Nuclear Waste Immobilization ◽  
Physical Phenomena

AbstractThe design and development of prototype cold crucible melters for waste vitrification are based on models of the basic physical phenomena, including electromagnetic induction and the thermal and hydraulic properties in natural or forced convection. The complexity of new nuclearized facilities results in significant errors on the results of predictive models based on 2D axisymmetric geometry that can only be resolved by modeling the device in 3D geometry. This document discusses the specification and electromagnetic design of a melter carried out using electromagnetic computation software, FLU3D, developed in 3D geometry by Cedrat. The principles and results of this study are directly applicable to nuclear facilities with allowance for the particular requirements of a nuclearized environment.

scholarly journals Face Mask Use in the Community for Reducing the Spread of COVID-19: A Systematic Review

2021 ◽  
Vol 7 ◽  
Author(s):  
Daniela Coclite ◽  
Antonello Napoletano ◽  
Silvia Gianola ◽  
Andrea del Monaco ◽  
Daniela D'Angelo ◽  
...  
Keyword(s):  
Systematic Review ◽  
Meta Analysis ◽  
Experimental Studies ◽  
Community Setting ◽  
Face Mask ◽  
Cochrane Library ◽  
Case Scenario ◽  
Materials Used ◽  
The Cochrane Library ◽  
Grade Approach

Background: Evidence is needed on the effectiveness of wearing face masks in the community to prevent SARS-CoV-2 transmission.Methods: Systematic review and meta-analysis to investigate the efficacy and effectiveness of face mask use in a community setting and to predict the effectiveness of wearing a mask. We searched MEDLINE, EMBASE, SCISEARCH, The Cochrane Library, and pre-prints from inception to 22 April 2020 without restriction by language. We rated the certainty of evidence according to Cochrane and GRADE approach.Findings: Our search identified 35 studies, including three randomized controlled trials (RCTs) (4,017 patients), 10 comparative studies (18,984 patients), 13 predictive models, nine laboratory experimental studies. For reducing infection rates, the estimates of cluster-RCTs were in favor of wearing face masks vs. no mask, but not at statistically significant levels (adjusted OR 0.90, 95% CI 0.78–1.05). Similar findings were reported in observational studies. Mathematical models indicated an important decrease in mortality when the population mask coverage is near-universal, regardless of mask efficacy. In the best-case scenario, when the mask efficacy is at 95%, the R0 can fall to 0.99 from an initial value of 16.90. Levels of mask filtration efficiency were heterogeneous, depending on the materials used (surgical mask: 45–97%). One laboratory study suggested a viral load reduction of 0.25 (95% CI 0.09–0.67) in favor of mask vs. no mask.Interpretation: The findings of this systematic review and meta-analysis support the use of face masks in a community setting. Robust randomized trials on face mask effectiveness are needed to inform evidence-based policies.PROSPERO registration: CRD42020184963.

Crystallization of neodymium-rich phases in silicate glasses developed for nuclear waste immobilization

2006 ◽  
Vol 354 (1-3) ◽  
pp. 143-162 ◽  
Author(s):  
D. Caurant ◽  
O. Majerus ◽  
P. Loiseau ◽  
I. Bardez ◽  
N. Baffier ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Silicate Glasses ◽  
Waste Immobilization ◽  
Nuclear Waste Immobilization
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