The Behaviours of Cementitious Materials in Long Term Storage and Disposal: An Overview of Results of the IAEA Coordinated Research Project

2009 ◽  
Vol 1193 ◽  
Author(s):  
Zoran Drace ◽  
Michael I. Ojovan
Keyword(s):  
Cementitious Materials ◽  
Research Project ◽  
Main Research ◽  
Long Term Storage ◽  
Research Organizations ◽  
And Performance ◽  
Long Term Performance ◽  
Term Performance ◽  
Cementitious Systems

AbstractCementitious materials are widely used in waste management systems with different aims and requirements for long term performance. Both conventional and novel cementitious materials are used to create reliable immobilising elements for safe storage and disposal of wastes. The barrier elements as well as interactions envisaged between various components are important to ultimately ensure the overall safety of a storage/disposal system. The behaviour and performance of cementitious materials including waste package components, wasteform and backfilling were analysed within the IAEA Coordinated Research Project which involved 26 research organizations from 21 Member States MS). The paper presents briefly the main research outcomes for conventional cementitious systems; novel materials and technologies; testing and waste acceptance criteria; and modelling long term behaviour.

scholarly journals Preparation, Physicochemical Properties, and Long-Term Performance of Photocatalytic Ceramsite Sand in Cementitious Materials

2017 ◽  
Vol 7 (8) ◽  
pp. 828 ◽  
Author(s):  
Du Zhao ◽  
Fazhou Wang ◽  
Peng Liu ◽  
Lu Yang ◽  
Shuguang Hu ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Cementitious Materials ◽  
Long Term Performance ◽  
Term Performance

Exhumation and performance of an Antarctic composite barrier system after 4 years exposure

2020 ◽  
Vol 57 (8) ◽  
pp. 1130-1152 ◽  
Author(s):  
R.S. McWatters ◽  
R.K. Rowe ◽  
V. Di Battista ◽  
B. Sfiligoj ◽  
D. Wilkins ◽  
...  
Keyword(s):  
High Density Polyethylene ◽  
Soil Samples ◽  
Composite Liner ◽  
Subgrade Soil ◽  
And Performance ◽  
Long Term Performance ◽  
Term Performance ◽  
The Antarctic ◽  
Coarse Gravel

An Antarctic biopile using a composite liner (high-density polyethylene geomembrane (GMB) over a geosynthetic clay liner (GCL)) was constructed on a coarse granular subgrade to contain hydrocarbon-contaminated soil and leachate. The soil was remediated after 4 years and the biopile was decommissioned. The liner was exhumed to assess the properties and performance of the GMB and GCL. There was no significant change in the GMB index properties. Although cobbles and coarse gravel of the subgrade had left indentations in the GMB, implying tensile strains that could impact long-term performance, there were no holes. There was significant variability in the hydration of the GCL (from 10% to 220%) and in the underlying subgrade soil water content (from 5% to 30%). This reflects the complexity of the subgrade and groundwater flow in the Antarctic environment. The exhumed GCL specimens had low hydraulic conductivity (1 × 10−11 to 7 × 10−11 m/s) at 13 kPa. Soil samples from below the composite liner showed no detectable hydrocarbons and confirmed no migration through the barrier. It is concluded that the composite barrier contained the leachate and biopile soil over the 4 years in service in the extreme Antarctic conditions.

Grouted Waste Leach Tests: Pursuit of Mechanisms and Data for Long-Term Performance Assessment

1989 ◽  
Vol 176 ◽  
Author(s):  
R. Jeff Serne
Keyword(s):  
Diffusion Processes ◽  
Scale Up ◽  
Liquid Waste ◽  
Effective Diffusivity ◽  
Cementitious Materials ◽  
Solidified Waste ◽  
Effective Diffusivities ◽  
Long Term Performance ◽  
Term Performance

ABSTRACTAt Hanford, low-level liquid nuclear waste is being mixed with cementitious materials (grout) to form leach-resistant solid waste. Prior to grouting each liquid waste, an assessment must be performed to evaluate the long-term environmental impact. These predictions rely upon a diffusioncontrolled release model and short-term laboratory leach data on small grout samples. This paper describes size scale-up and inventory scale-up experiments that evaluate whether diffusion does in fact control the release of contaminants. The results of the volume scale-up test suggest that tests on grout cylinders between the sizes 3 cm dia. by 3 cm length and 30 cm dia. by 29 cm length yield comparable results. These data and other available literature suggest that extrapolation of leach results to large blocks of solidified waste is defensible.The inventory scale-up tests for 125I and selenium show a constant effective diffusivity regardless of the original inventory. This suggests that diffusion processes do in fact control the release of iodide and selenium from grout. The 99Tc effective diffusivities may not remain constant with changes in inventory.

Cementitious Materials for Radioactive Waste Management Within IAEA Coordinated Research Project

2011 ◽  
Author(s):  
Zoran Drace ◽  
Michael I. Ojovan
Keyword(s):  
Radioactive Waste ◽  
Waste Management ◽  
Cementitious Materials ◽  
Radioactive Waste Management ◽  
Long Term Storage ◽  
Waste Immobilization ◽  
Materials Used ◽  
Cementitious Systems ◽  
Term Storage

The IAEA Coordinated Research Project (CRP) on cementitious materials for radioactive waste management was launched in 2007 [1, 2]. The objective of CRP was to investigate the behaviour and performance of cementitious materials used in radioactive waste management system with various purposes and included waste packages, wasteforms and backfills as well as investigation of interactions and interdependencies of these individual elements during long term storage and disposal. The specific research topics considered were: (i) cementitious materials for radioactive waste packaging: including radioactive waste immobilization into a solid waste form, (ii) waste backfilling and containers; (iii) emerging and alternative cementitious systems; (iv) physical-chemical processes occurring during the hydration and ageing of cement matrices and their influence on the cement matrix quality; (v) methods of production of cementitious materials for: immobilization into wasteform, backfills and containers; (vi) conditions envisaged in the disposal environment for packages (physical and chemical conditions, temperature variations, groundwater, radiation fields); (vii) testing and nondestructive monitoring techniques for quality assurance of cementitious materials; (viii) waste acceptance criteria for waste packages, waste forms and backfills; transport, long term storage and disposal requirements; and finally (ix) modelling or simulation of long term behaviours of cementations materials used for packaging, waste immobilization and backfilling, especially in the post-closure phase. The CRP has gathered overall 26 research organizations from 22 Member States aiming to share their research and practices on the use of cementitious materials [2]. The main research outcomes of the CRP were summarized in a summary report currently under preparation to be published by IAEA. The generic topical sections covered by report are: a) conventional cementitious systems; b) novel cementitious materials and technologies; c) testing and waste acceptance criteria; and d) modelling long term behaviour. These themes as well as all contributions of participating organizations were further developed in the individual reports to be presented in the IAEA publication. The CRP facilitated the exchange of information and research co-operation in resolving similar problems between different institutions and contributed towards improving waste management practices, their efficiency and general enhancement of safety.

The Long-Term Safety and Performance Analyses of the Surface Disposal Facility for the Belgian Category A Waste at Dessel

2013 ◽  
Author(s):  
Wim Cool ◽  
Elise Vermariën ◽  
William Wacquier ◽  
Janez Perko
Keyword(s):  
Radioactive Waste ◽  
Radiological Criteria ◽  
Disposal Facility ◽  
Safety Function ◽  
License Application ◽  
Performance Analyses ◽  
And Performance ◽  
Long Term Performance ◽  
Term Performance

ONDRAF/NIRAS, the Belgian Agency for Radioactive Waste and Enriched Fissile Materials, and its partners have developed long-term safety and performance analyses in the framework of the license application for a surface disposal facility for low level radioactive waste (category A waste) at Dessel, Belgium. This paper focusses on the methodology of the safety assessments and on key results from the application of this methodology. An overview is given (1) of the performance analyses for the containment safety function of the disposal system and (2) of the radiological impact analyses confirming that radiological impacts are below applicable reference values and constraints and leading to radiological criteria for the waste and the facility. In this discussion, multiple indicators for performance and safety are used to illustrate the multi-faceted nature of long-term performance and safety of the surface disposal. This contributes to the multiple lines of reasoning for confidence building that a positive decision to proceed to the next stage of construction is justified.

scholarly journals STRATEGI DAN KINERJA DALAM SISTEM KOMPENSASI

2014 ◽  
Vol 5 (2) ◽  
Author(s):  
Mimin Nur Aisyah
Keyword(s):  
Stock Price ◽  
Compensation System ◽  
Incentive System ◽  
Goal Congruence ◽  
Company Stock ◽  
And Performance ◽  
Line Manager ◽  
Long Term Performance ◽  
Term Performance

Compensation system has been broadly discussed because of its significant role in enhancing productivity dan performance. It able to motivate a goal directed behavior. Compensation system is expected to provide organizational goal congruence. There are several norms that will lead to different reward distribution. In determining what compensation system that should be taken, organization should consider these dimensions: (1) short term vs long term, (2) cash vs equity, and (3) monetary vs non monetary. Strategy and performance play important role in organizational compensation system. Empirical evidences had support the relation between company’s strategy and its incentive system. Strategic orientation has significant effect on incentive system. To intervene the gap between what is actually needed from compensation system and its practices, the design of reward system should be improved through: (1) give reward to managers only if they perform better than competitors, (2) determine the contribution of each business unit to company stock price, and (3) involve the contribution of front line manager and employees in achieving higher shareholder values. Theory has supports the effectiveness of compensation system, but some evidences showed the contrary. The failness of incentive plans to motivate long term performance should drive the organization to improve the design and implementation of the existed system or to create a new and more effective incentive system.

The contrasting moderating effect of exploration on the relationship between stock options/stock ownership and a firm’s long-term performance

2018 ◽  
Vol 56 (9) ◽  
pp. 1956-1968 ◽  
Author(s):  
Gun Jea Yu ◽  
Joonkyum Lee
Keyword(s):  
Stock Options ◽  
Chief Executive ◽  
Moderating Effect ◽  
Stock Ownership ◽  
Content Type ◽  
And Performance ◽  
Long Term Performance ◽  
Term Performance ◽  
The Relationship

Purpose The purpose of this paper is to investigate the contrasting moderating effect of a firm’s exploration on the relationship between the two types of long-term incentives (stock options/stock ownership) for the chief executive officers and a firm’s long-term performance. Even though the two types of incentives are designed to improve long-term performance, the degrees of impact on long-term performance differ. Based on behavioral agency theory, this study theoretically and empirically examines the role of a firm’s exploration on the above relationship. Design/methodology/approach This study used three archival sources to obtain data on stock options, stock ownership, patents and exploration, financial measures, and others. Based on a sample of 1,963 firms in various industries from 1995 to 2006, this study tested the moderating effect of a firm’s exploration on the relationship between stock options/ownership and a firm’s performance. Findings This study reveals the contrasting moderating effect of a firm’s exploration on the relationship between stock options/ownership and a firm’s long-term performance: a positive moderating effect on the relationship between stock options and performance and a negative moderating effect on the relationship between stock ownership and performance. In addition, empirical evidence was added on the inverted U-shaped relationship between stock ownership and a firm’s long-term performance. Originality/value There is little research on a firm’s internal characteristics that strengthen or weaken the effects of stock options and stock ownership on firm performance. This study demonstrates the differential moderating effects of exploration on the relationship between stock options/stock ownership and long-term performance. Such effects of exploration come from the different risk features of stock options and stock ownership. The key implication is that stock options could be more effective than stock ownership to enhance a firm’s long-term performance when a firm has a strong exploration orientation.

Study on the Effects of Natural Pozzolan and Limestone Powder on Mechanical Properties of Roller Compacted Concrete Pavements

2011 ◽  
Vol 250-253 ◽  
pp. 3619-3623 ◽  
Author(s):  
Morteza Madhkhan ◽  
Armin Hamidi ◽  
Navid Salehi
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Production Costs ◽  
Limestone Powder ◽  
Concrete Pavements ◽  
Natural Pozzolan ◽  
Two Factors ◽  
Long Term Performance ◽  
Term Performance

Due to high maintenance and production costs of conventional asphalt pavements in recent years, substitution of concrete pavements has been taken into account. One important factor of such pavements is the long-term performance. The substitution of pozzolanic materials with existing cement in the mixture is a common choice to improve the durability factors and to increase the long term compressive strength. Owing to this change in cementitious materials, a general anticipation of the pozzolanic behavior to be observed is that the early age compressive strength gets decreased. On the other hand, this defect will be compensated in the long-term compressive strength. Furthermore, as conventional loads of road pavements are concerned, the tensile and flexural strengths have their own importance. Regarding these two factors, the related tests were also performed and the results were analyzed. The main purpose is to find the optimum material among these 2 types of pozzolanic supplements and its percentage of substitution with the preference of having the best average strength in both long and short term performances. Altogether, the natural pozzolan had better performance than limestone powder.

WARMING ISSUES ASSOCIATED WITH THE LONG TERM SIMULATION OF HOUSING USING CFD ANALYSIS

2016 ◽  
Vol 11 (2) ◽  
pp. 57-74 ◽  
Author(s):  
Aiman Albatayneh ◽  
Dariusz Alterman ◽  
Adrian W. Page ◽  
Behdad Moghtaderi
Keyword(s):  
Air Temperature ◽  
Cfd Simulation ◽  
Heating And Cooling ◽  
And Performance ◽  
External Volume ◽  
Cooling Loads ◽  
Long Term Performance ◽  
Term Performance

The determination of internal building air temperature has an impact on the design and performance of a building in measuring thermal comfort and heating and cooling loads. There is software to assist with measuring internal building air temperature such as Autodesk CFD simulation. However, the use of Autodesk CFD simulation for the analysis appears to have an issue with simulations extending over a long term (i.e. months or years) as the internal air temperature in a building keeps rising with time. This paper addresses the challenges encountered using CFD simulation in the modelling of a building for long term performance. A new method to overcome the issue of the progressive rising of internal air temperature using two external air boundaries, one for the external volume (sky boundary) and the other surrounding the building, is suggested in the paper.

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