The Effect of EDZ on the Migration of Radionuclides in a KBS-3 Type Repository

2003 ◽  
Vol 807 ◽  
Author(s):  
Jorma Autio ◽  
Thomas Hjerpe ◽  
Marja Siitari-Kauppi
Keyword(s):  
Spent Nuclear Fuel ◽  
Hard Rock ◽  
State Of The Art ◽  
Migration Route ◽  
Excavation Damaged Zone ◽  
Tunnel Floor ◽  
Damaged Zone ◽  
Hydraulic Gradients ◽  
Drill And Blast

ABSTRACTThe role of excavation damaged zone (EDZ) in a KBS-3 type repository for spent nuclear fuel depends significantly on the design of the engineered barrier systems such as tunnel backfill since one obvious function of the backfill is to prevent the growth of EDZ. Main results of EDZ studies based on using 14C-PMMA method carried out at Äspö Hard Rock Laboratory in Sweden, and at Research Tunnel at Olkiluoto in Finland by Posiva and SKB in co-operation are presented. The significance of the results is evaluated quantitatively and qualitatively. The EDZ around the deposition hole on migration of radionuclides diffusing out of a waste canister was found unlikely to be a significant migration route in the absence of large hydraulic gradients. According to the study the EDZ caused by state-of-the-art drill and blast excavation adjacent to walls and roof of deposition tunnels was found negligible, however the EDZ adjacent to deposition tunnel floor is evidently more extensive and more significant.

The Effect of the Excavation Damaged Zone Adjacent to the Walls of Deposition Holes on the Migration of Radionuclides

2000 ◽  
Vol 663 ◽  
Author(s):  
J. Autio ◽  
A. Hautojärvi ◽  
J-P. Salo
Keyword(s):  
Hydraulic Conductivity ◽  
Nuclear Waste ◽  
Nuclear Waste Repository ◽  
Migration Route ◽  
Compacted Bentonite ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Hydraulic Gradients ◽  
Waste Repository ◽  
And Diffusion

ABSTRACTThe excavation damaged rock zone (EDZ) adjacent to the surface of deposition holes in a nuclear waste repository has been considered to be a potential pathway for the flow of water and the migration of radionuclides diffusing out of a waste canister via the bentonite barrier. The properties of the excavation-damaged rock zone adjacent to the surface of experimental deposition holes in the Research Tunnel at Olkiluoto on the southwest coast of Finland have been measured and are used in this study to evaluate the effect of the excavation damaged rock zone on the transport of radionuclides escaping from a waste canister. Since the hydraulic conductivity of compacted bentonite is low, the predominant mode of migration of nuclides through such material will be diffusion. The effect of the excavation-damaged rock zone on the transport of radionuclides was analyzed by comparing two different cases: 1) diffusion through the bentonite and 2) transport through the excavation damaged rock zone by the processes of advection and diffusion. According to this study, hydraulic gradients three orders of magnitude higher than those estimated to currently exist would be required to achieve the transfer of significant quantities of non-sorbing neutral nuclides through the excavation-damaged rock zone. According to this evaluation, the excavation damaged rock zone is unlikely to be a significant migration route in normal cases in the absence of large hydraulic gradients.

scholarly journals The Method of Determining Excavation Damaged Zone by Acoustic Test and the Application in Engineering Cases

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Qian-Cheng Sun ◽  
Hao-Sen Guo ◽  
Zhi-Hua Xu ◽  
Yue Liu ◽  
Xiao Xu
Keyword(s):  
Rock Mass ◽  
Damage Evolution ◽  
Hard Rock ◽  
Damage Zone ◽  
Jointed Rock ◽  
Jointed Rock Mass ◽  
Surrounding Rock ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Columnar Jointed Rock Mass

It is very important to accurately determine the depth of excavation damaged zone for underground engineering excavation and surrounding rock stability evaluation, and it can be measured by acoustic test, but there is no quantitative method for analysis of the results, and it relies heavily on the experience of engineers, which leads to the low reliability of the results and also limits the application of the acoustic method. According to substantial field test data and the feedback of surrounding rock support parameters, the boundary method is proposed to determine the depth of excavation damaged zone in surrounding rock based on the relation between the ultrasonic velocity of measured point and the background wave velocity of rock mass. When the method is applied to the columnar jointed rock mass of Baihetan and the deep-buried hard rock of Jinping, the excavation damaged zone was well judged. The results in the Baihetan project show that the proposed method of determining excavation damage zone by the acoustic test can well demonstrate the anisotropy characteristics of the columnar jointed rock mass, and the damage evolution characteristics of jointed rock mass at the same position can also be obtained accurately. Moreover, the method also can accurately reveal the damage evolution process of the deep-buried hard rock under the condition of high ground stress, which proved the applicability of this method in jointed or nonjointed rock masses.

Compacted bentonite as a source of substrates for sulfate-reducing microorganisms in a simulated excavation-damaged zone of a spent nuclear fuel repository

2020 ◽  
Vol 196 ◽  
pp. 105746
Author(s):  
Susanna Maanoja ◽  
Aino-Maija Lakaniemi ◽  
Leena Lehtinen ◽  
Linda Salminen ◽  
Hannele Auvinen ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Sulfate Reducing ◽  
Compacted Bentonite ◽  
Excavation Damaged Zone ◽  
Damaged Zone

Excavation Damage Zone in the Experimental Deposition Holes at Äspö and Comparison to Existing Data

2003 ◽  
Vol 807 ◽  
Author(s):  
Jorma Autio ◽  
Hanna Malmlund ◽  
Thomas Hjerpe ◽  
Maarit Kelokaski ◽  
Marja Siitari-Kauppi
Keyword(s):  
Hard Rock ◽  
Damage Zone ◽  
High Level Waste ◽  
Excavation Damaged Zone ◽  
Damaged Zone ◽  
Crushed Zone ◽  
High Level ◽  
Excavation Damage ◽  
The Impact ◽  
Clear Increase

ABSTRACTDisposal in deep, stable bedrock is currently one concept for isolating high-level wastes from the environment. Repository for high-level waste in rock excavated using different drilling techniques is surrounded by an excavation damaged zone (EDZ) which properties have been changed. The micro fracturing of samples taken from the experimental deposition holes in the underground Hard Rock Laboratory at Äspö were investigated by the 14C polymethylmetha-crylate (14C-PMMA) method and scanning electron microscopy (SEM) to evaluate the impact of EDZ on migration. The porosity of the damaged rock zone is clearly higher than the porosity of undisturbed rock. The thickness of the crushed zone with significantly higher porosity is a few millimetres and the average depth of the damaged zone (i.e. a clear increase in porosity found) is from 5 to 20 mm from the hole wall. The apertures of the inter- and intragranular fractures in the crushed zone varied from 5 to 30 μm according to SEM examination. Earlier results of porosity, diffusivity and permeability measurements in granites were compiled and the results of the porosity values of Äspö diorite were compared to the porosity values measured in other types of granites. The results were compiled in permeability-diffusivity-porosity space and were found to form a plane that could be used to estimate the range of diffusivity and permeability of the Äspö diorite.

Coinage and the Tributary Mode of Production

2018 ◽  
Author(s):  
Eduardo Manzano Moreno
Keyword(s):  
Roman Empire ◽  
Middle Ages ◽  
Social Role ◽  
State Of The Art ◽  
Early Middle Ages ◽  
The Social ◽  
Simple Question ◽  
Mode Of Production

This chapter addresses a very simple question: is it possible to frame coinage in the Early Middle Ages? The answer will be certainly yes, but will also acknowledge that we lack considerable amounts of relevant data potentially available through state-of-the-art methodologies. One problem is, though, that many times we do not really know the relevant questions we can pose on coins; another is that we still have not figured out the social role of coinage in the aftermath of the Roman Empire. This chapter shows a number of things that could only be known thanks to the analysis of coins. And as its title suggests it will also include some reflections on greed and generosity.

scholarly journals Water-Worked Gravel Bed: State-of-the-Art Review

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 694 ◽  
Author(s):  
Ellora Padhi ◽  
Subhasish Dey ◽  
Venkappayya R. Desai ◽  
Nadia Penna ◽  
Roberto Gaudio
Keyword(s):  
State Of The Art ◽  
Flow Characteristics ◽  
Streamwise Velocity ◽  
Secondary Currents ◽  
Gravel Bed ◽  
Natural Stream ◽  
Art Research ◽  
The Comparative Study ◽  
Water Work

In a natural gravel-bed stream, the bed that has an organized roughness structure created by the streamflow is called the water-worked gravel bed (WGB). Such a bed is entirely different from that created in a laboratory by depositing and spreading gravels in the experimental flume, called the screeded gravel bed (SGB). In this paper, a review on the state-of-the-art research on WGBs is presented, highlighting the role of water-work in determining the bed topographical structures and the turbulence characteristics in the flow. In doing so, various methods used to analyze the bed topographical structures are described. Besides, the effects of the water-work on the turbulent flow characteristics, such as streamwise velocity, Reynolds and form-induced stresses, conditional turbulent events and secondary currents in WGBs are discussed. Further, the results form WGBs and SGBs are compared critically. The comparative study infers that a WGB exhibits a higher roughness than an SGB. Consequently, the former has a higher magnitude of turbulence parameters than the latter. Finally, as a future scope of research, laboratory experiments should be conducted in WGBs rather than in SGBs to have an appropriate representation of the flow field close to a natural stream.

scholarly journals From Exosome Glycobiology to Exosome Glycotechnology, the Role of Natural Occurring Polysaccharides

2021 ◽  
Vol 2 (2) ◽  
pp. 311-338
Author(s):  
Giulia Della Rosa ◽  
Clarissa Ruggeri ◽  
Alessandra Aloisi
Keyword(s):  
State Of The Art ◽  
Cell Communication ◽  
Pathological Conditions ◽  
New Findings ◽  
Cell Type Specific ◽  
New Perspective ◽  
And Function ◽  
And Personalized Medicine ◽  
Innate Ability

Exosomes (EXOs) are nano-sized informative shuttles acting as endogenous mediators of cell-to-cell communication. Their innate ability to target specific cells and deliver functional cargo is recently claimed as a promising theranostic strategy. The glycan profile, actively involved in the EXO biogenesis, release, sorting and function, is highly cell type-specific and frequently altered in pathological conditions. Therefore, the modulation of EXO glyco-composition has recently been considered an attractive tool in the design of novel therapeutics. In addition to the available approaches involving conventional glyco-engineering, soft technology is becoming more and more attractive for better exploiting EXO glycan tasks and optimizing EXO delivery platforms. This review, first, explores the main functions of EXO glycans and associates the potential implications of the reported new findings across the nanomedicine applications. The state-of-the-art of the last decade concerning the role of natural polysaccharides—as targeting molecules and in 3D soft structure manufacture matrices—is then analysed and highlighted, as an advancing EXO biofunction toolkit. The promising results, integrating the biopolymers area to the EXO-based bio-nanofabrication and bio-nanotechnology field, lay the foundation for further investigation and offer a new perspective in drug delivery and personalized medicine progress.

scholarly journals Role of long non‐coding RNAs in adipogenesis: State of the art and implications in obesity and obesity‐associated diseases

2021 ◽  
Author(s):  
Federica Rey ◽  
Valentina Urrata ◽  
Luisa Gilardini ◽  
Simona Bertoli ◽  
Valeria Calcaterra ◽  
...  
Keyword(s):  
State Of The Art ◽  
Associated Diseases ◽  
Non Coding Rnas

scholarly journals Multifunctional Role of Chitosan Edible Coatings on Antioxidant Systems in Fruit Crops: A Review

2021 ◽  
Vol 22 (5) ◽  
pp. 2633
Author(s):  
Giuseppina Adiletta ◽  
Marisa Di Matteo ◽  
Milena Petriccione
Keyword(s):  
State Of The Art ◽  
Antioxidant Systems ◽  
Edible Coatings ◽  
Ros Production ◽  
Oxygen Species ◽  
Fruit Crops ◽  
Oxidative Damages ◽  
Film Forming ◽  
Anti Oxidant

Chitosan-based edible coatings represent an eco-friendly and biologically safe preservative tool to reduce qualitative decay of fresh and ready-to-eat fruits during post-harvest life due to their lack of toxicity, biodegradability, film-forming properties, and antimicrobial actions. Chitosan-based coatings modulate or control oxidative stress maintaining in different manner the appropriate balance of reactive oxygen species (ROS) in fruit cells, by the interplay of pathways and enzymes involved in ROS production and the scavenging mechanisms which essentially constitute the basic ROS cycle. This review is carried out with the aim to provide comprehensive and updated over-view of the state of the art related to the effects of chitosan-based edible coatings on anti-oxidant systems, enzymatic and non-enzymatic, evaluating the induced oxidative damages during storage in whole and ready-to-eat fruits. All these aspects are broadly reviewed in this review, with particular emphasis on the literature published during the last five years.

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