The Effect of Temperature and Composition on Spinel Concentration and Crystal Size in High-Level Waste Glass

2001 ◽  
Author(s):  
Martin Mika ◽  
Milan Patek ◽  
Jaroslav Maixner ◽  
Simona Randakova ◽  
Pavel Hrma
Keyword(s):  
Crystal Size ◽  
Equilibrium Concentration ◽  
Effect Of Temperature ◽  
High Level Waste ◽  
Huge Number ◽  
Aluminoborosilicate Glass ◽  
High Level ◽  
The Cost ◽  
Different Content ◽  
The Mathematical Model

Abstract High-level radioactive wastes can be safely immobilized in alkali-aluminoborosilicate glass. To reduce the cost of the vitrification process, the waste loading should be maximized. This can be done by optimizing the process using mathematical modeling. The main objective of our work was to determine one of the necessary inputs for the mathematical model, which is the effect of temperature and composition on the concentration of spinel crystals and their size. We prepared six glasses with a different content of Li+, Na+, Mg2+, Ni2+, Cr3+, and SiIV and studied the effect of composition on the temperature dependence of spinel equilibrium concentration in glass by X-ray powder diffraction. The size of crystals was determined using optical microscopy. It was found that the temperature effect on spinel concentration significantly increased as the content of Ni2+ or Mg2+ in glass increased and slightly decreased as the content of Cr3+ increased and Li+ and Na+ content decreased. Both Ni2+ and Cr3+ acted as nucleating agents, producing a huge number of tiny spinel crystals (∼2 μm). In particular, Ni2+ seems to very significantly facilitate spinel crystallization.

The role of the canister in a system for the final disposal of spent fuel or high-level waste

1986 ◽  
Vol 319 (1545) ◽  
pp. 39-47 ◽  
Keyword(s):  
Crystalline Rock ◽  
High Level Waste ◽  
Public Confidence ◽  
Toxic Substances ◽  
Spent Fuel ◽  
Geochemical Environment ◽  
Safety Margins ◽  
Safety Effect ◽  
High Level ◽  
The Cost

A final repository for radioactive waste must isolate the toxic substances or distribute their release over time or space to avoid causing harmful concentrations of radionuclides in the biosphere. The Swedish research has focused on a repository 500 m down in crystalline rock where the geochemical environment can give canisters a service life of the order of a million years. These evaluations are discussed and the safety effect of the canister is compared with that of other barriers available in a repository system. Our conclusions are that a combined protection effect of natural and man-made barriers can be achieved that substantially exceeds what could reasonably be required by society. An actual repository design can then be based on an optimization of the cost to reach a level of accepted safety with due regard for the safety margins and redundancy necessary for achieving public confidence.

A Framework for Assessing the Cost and Financing Uncertainties of the Belgian High Level-Waste Repository

2003 ◽  
Author(s):  
P. L. Kunsch
Keyword(s):  
Fuzzy Logic ◽  
Electric Power Research Institute ◽  
High Level Waste ◽  
Mathematical Technique ◽  
Final Design ◽  
High Level ◽  
The Cost ◽  
Fuzzy Logic Technique ◽  
Hlw Repository ◽  
Natural Way

This paper presents the general approach presently developed by ONDRAF/NIRAS/NERAS, the Belgian radioactive waste management agency for dealing with the economic and financial uncertainties of the High-level-Waste (HLW) repository project in clay. This project will be for many more years the object of R&D studies. Many uncertainties thus still exist regarding the final design, the eventual costs, and the realisation schedule. Recommendations from the Electric Power Research Institute (EPRI) are available for computing contingency factors to be applied on top of the basic costs delivered by project engineers. We show in this paper that fuzzy logic is a natural way to use the recommendations of EPRI. Fuzzy logic is a mathematical technique for representing unprecise or relatively vague judgments made by experts, like: ‘this project is preliminary’, ‘this concept is insufficiently mature’, etc. This approach is considered in many fields as being well-suited for coping with uncertainties implied by such judgments. In the present case, distinction is made between uncertainties related to policy, project, technology, and realisation schedule. The paper details the sequence of basic steps used by the agency to produce as a final product the per-unit tariff of the different waste categories. Expert judgments are interpreted by the fuzzy-logic technique to derive EPRI-like contingency factors for each project task, as well as a fuzzy operating schedule within a given political scenario. Conclusions are given on how this approach can be validated and set into practice.

Micron-sized spinel crystals in high level waste glass compositions: Determination of crystal size and crystal fraction

2019 ◽  
Vol 514 ◽  
pp. 196-207
Author(s):  
C.E. Lonergan ◽  
K. Akinloye-Brown ◽  
J. Rice ◽  
V. Gervasio ◽  
N. Canfield ◽  
...  
Keyword(s):  
Crystal Size ◽  
Waste Glass ◽  
High Level Waste ◽  
Crystal Fraction ◽  
High Level ◽  
Glass Compositions

Changing Role of Agriculture in Income and Employment, and Trends of Agricultural Worker Productivity in Indian States

2020 ◽  
pp. 183-189
Keyword(s):  
Green Revolution ◽  
Positive Trend ◽  
Worker Productivity ◽  
Indian States ◽  
Agricultural Worker ◽  
The Sixties ◽  
High Level ◽  
The Cost ◽  
Changing Role

The productivity of land has been often discussed and deliberated by the academia and policymakers to understand agriculture, however, very few studies have focused on the agriculture worker productivity to analyze this sector. This study concentrates on the productivity of agricultural workers from across the states taking two-time points into consideration. The agriculture worker productivity needs to be dealt with seriously and on a time series basis so that the marginal productivity of worker can be ascertained but also the dependency of worker on agriculture gets revealed. There is still disguised unemployment in all the states and high level of labour migration, yet most of the states showed the dependency has gone down. Although a state like Madhya Pradesh is doing very well in terms of income earned but that is at the cost of increased worker power in agriculture as a result of which, the productivity of worker has gone down. States like Mizoram, Meghalaya, Nagaland and Tripura, though small in size showed remarkable growth in productivity and all these states showed a positive trend in terms of worker shifting away from agriculture. The traditional states which gained the most from Green Revolution of the sixties are performing decently well, but they need to have the next major policy push so that they move to the next orbit of growth.

scholarly journals Determining the critical period for weed control in high-yielding cotton using common sunflower as a mimic weed

2019 ◽  
Vol 33 (6) ◽  
pp. 800-807 ◽  
Author(s):  
Graham W. Charles ◽  
Brian M. Sindel ◽  
Annette L. Cowie ◽  
Oliver G. G. Knox
Keyword(s):  
Weed Control ◽  
Critical Period ◽  
Yield Loss ◽  
Field Studies ◽  
Growing Degree Days ◽  
Degree Days ◽  
Weed Density ◽  
High Level ◽  
The Cost ◽  
Planting Season

AbstractField studies were conducted over six seasons to determine the critical period for weed control (CPWC) in high-yielding cotton, using common sunflower as a mimic weed. Common sunflower was planted with or after cotton emergence at densities of 1, 2, 5, 10, 20, and 50 plants m−2. Common sunflower was added and removed at approximately 0, 150, 300, 450, 600, 750, and 900 growing degree days (GDD) after planting. Season-long interference resulted in no harvestable cotton at densities of five or more common sunflower plants m−2. High levels of intraspecific and interspecific competition occurred at the highest weed densities, with increases in weed biomass and reductions in crop yield not proportional to the changes in weed density. Using a 5% yield-loss threshold, the CPWC extended from 43 to 615 GDD, and 20 to 1,512 GDD for one and 50 common sunflower plants m−2, respectively. These results highlight the high level of weed control required in high-yielding cotton to ensure crop losses do not exceed the cost of control.

scholarly journals Computing the Exact Number of Similarity Classes in the Longest Edge Bisection of Tetrahedra

Mathematics ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1447
Author(s):  
Jose P. Suárez ◽  
Agustín Trujillo ◽  
Tania Moreno
Keyword(s):  
Data Structure ◽  
Stability Condition ◽  
Open Problem ◽  
Integer Arithmetic ◽  
Exact Number ◽  
Similarity Class ◽  
The Stability ◽  
High Level ◽  
The Cost

Showing whether the longest-edge (LE) bisection of tetrahedra meshes degenerates the stability condition or not is still an open problem. Some reasons, in part, are due to the cost for achieving the computation of similarity classes of millions of tetrahedra. We prove the existence of tetrahedra where the LE bisection introduces, at most, 37 similarity classes. This family of new tetrahedra was roughly pointed out by Adler in 1983. However, as far as we know, there has been no evidence confirming its existence. We also introduce a new data structure and algorithm for computing the number of similarity tetrahedral classes based on integer arithmetic, storing only the square of edges. The algorithm lets us perform compact and efficient high-level similarity class computations with a cost that is only dependent on the number of similarity classes.

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