Near-Field Chemical Composition of Porewaters in a Near-Surface Low-Level Radioactive Waste Vault

1996 ◽  
Vol 465 ◽  
Author(s):  
F. Caron ◽  
M. K. Haas ◽  
G. Manni ◽  
J. Torok
Keyword(s):  
Volatile Fatty Acids ◽  
Near Field ◽  
Inorganic Ions ◽  
Relative Distribution ◽  
Near Surface ◽  
Low Level ◽  
Major Species ◽  
Typical Composition ◽  
Waste Degradation

ABSTRACTA long-term waste degradation experiment has been performed with actual low-level radioactive wastes (LLRW) at the Chalk River Laboratories (CRL), to support the licensing and modelling efforts for near-surface disposal. The wastes consist of paper, mop heads, paper towels, used clothing, etc. The wastes were compacted into bales and sealed into separate steel containers, which were connected to leachate collection systems for sampling. The leachates collected had a composition typical of landfill leachates. The major inorganic ions were Na, Ca, Cl, and Fe, and the ionic strength was ∼0.05 M. The relative distribution of inorganic ions in the leachates was remarkably similar between bales. Volatile fatty acids (VFA) were the major species of dissolved organic carbon (DOC, total DOC up to 7000 mg/L). A typical composition of leachates is proposed, which can be used in geochemical and source term modelling.

Detailed Description of a Long-Term Low-Level Waste Degradation Experiment

1996 ◽  
Vol 465 ◽  
Author(s):  
F. Caron ◽  
J. Torok ◽  
M. K. Haas ◽  
G. Manni
Keyword(s):  
Landfill Leachates ◽  
Near Surface ◽  
Low Level ◽  
Dissolved Organics ◽  
Safety Case ◽  
Waste Degradation ◽  
Paper Towels ◽  
Low Level Radioactive Waste

ABSTRACTThis work gives a detailed description of the important aspects of a long-term Low-Level Radioactive Waste (LLRW) degradation experiment, performed at Chalk River Laboratories (CRL). This experiment utilized actual LLRW. The wastes consist of unconditioned compacted refuse (paper, mop heads, paper towels, used clothing, etc), which represents the bulk of the waste volume intended for near-surface disposal at CRL. Waste material was collected and compacted to make a total of 11 bales for this experiment. Each bale was then placed and sealed in separate steel containers which were connected to sampling lines. After a dry monitoring period, water was added to promote leaching and decomposition of the wastes. The leachate sampled had a composition similar to landfill leachates. Some applications of this experiment, used to support the safety case of near-surface disposal, are briefly discussed in this paper, e.g., the production of colloidal material, the nature and role of dissolved organics of microbial origin, etc.

Modelling of a Generic Near-Surface Disposal System

2012 ◽  
Vol 1475 ◽  
Author(s):  
Noelia R. Sileo ◽  
Néstor O. Fuentes
Keyword(s):  
Performance Assessment ◽  
Waste Disposal ◽  
Near Field ◽  
Simple Calculation ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Near Surface ◽  
License Application ◽  
Numerical Tools

ABSTRACTDevelopment of numerical tools for performance assessment studies of radioactive waste disposal facilities, must address the management of the wide-ranging uncertainties associated with the long-term behaviour of these complex systems. Different approaches and assumptions are made in order to identify and describe relationships between the disposal system and its environment. They take into account, among other factors, the uncertainties associated with temporal evolution of the system within a proposed scenario; the landscape changes arising from future human actions, climate and geological events and processes; the relationships between components of the disposal system and its immediate environment; the behaviour and characteristics of radionuclides within the system and their role in contributing to radiation exposure. In all cases, the different scenario-based models are typically used to determine the radiological significance of potential future discharges from waste disposal facilities. However, it is important to keep always in mind that in any specific case, the purpose of developing and/or applying a model may vary from a simple calculation (e.g. to support concept development) to detailed site-specific performance assessment in support of a disposal license application. The assumptions and modelling simplifications that are appropriate to one type of calculation may not be so easily justified in different circumstances. In order to develop the capability of modelling different long-term scenarios for a generic disposal site for low and intermediate level radioactive wastes, implementation of models of both the near-field/geosphere and biosphere were performed using general approaches for geosphere-biosphere interface, with sub-models for the whole system.

scholarly journals An Integrated Testing Program for a Near-Field Radionuclide Migration Code

1997 ◽  
Vol 506 ◽  
Author(s):  
P. Binks ◽  
A. Fairhurst ◽  
D. Howarth ◽  
P. N. Humphreys ◽  
T. Johnstone ◽  
...  
Keyword(s):  
Near Field ◽  
Field Studies ◽  
Test Cases ◽  
Radionuclide Migration ◽  
Near Surface ◽  
Transport Code ◽  
Liquid Source ◽  
Integrated Testing ◽  
Main Components

ABSTRACTThe DRINK code is a 2D, biogeochemical transport code developed as a research tool to simulate the long term evolution of near surface LLW disposal sites and to generate gaseous and liquid source terms for far field studies. The code was recently upgraded to provide a more generic modelling tool with wider application to radionuclide migration scenarios. During the development of this code, the Generalised Repository Model (GRM), an integrated strategy has been employed to ensure the production of a fully tested, verified and quality assured product. This strategy is based around a code development protocol with three main components: quality assurance and documentation, verification and realism testing. Realism testing includes both peer review and model testing, with the latter including: experimental test cases; natural and anthropogenic analogues; field observations and finally uncertainty and sensitivity analysis. This paper describes the successful application of the protocol to the development and testing of the GRM code with specific emphasis upon verification and realism testing.

DEVELOPMENT OF VERY LOW-LEVEL RADIOACTIVE WASTE SEQUESTRATION PROCESS CRITERIA

2015 ◽  
Vol 4 (2) ◽  
pp. 119-123
Author(s):  
Nicholas Chan ◽  
Pierre Wong
Keyword(s):  
Radioactive Waste ◽  
Waste Management ◽  
Low Cost ◽  
Regulatory Control ◽  
Environmental Footprint ◽  
Near Surface ◽  
Low Level ◽  
High Degree ◽  
Low Level Radioactive Waste

Segregating radioactive waste at the source and reclassifying radioactive waste to lower waste classes are the key activities to reduce the environmental footprint and long-term liability. In the Canadian Standards Association’s radioactive waste classification system, there are 2 sub-classes within low-level radioactive waste: very short-lived radioactive waste and very low-level radioactive waste (VLLW). VLLW has a low hazard potential but is above the Canadian unconditional clearance criteria as set out in Schedule 2 of Nuclear Substances and Devices Regulations. Long-term waste management facilities for VLLW do not require a high degree of containment and isolation. In general, a relatively low-cost near-surface facility with limited regulatory control is suitable for VLLW. At Canadian Nuclear Laboratories’ Chalk River Laboratories site an initiative, VLLW Sequestration, was implemented in 2013 to set aside potential VLLW for temporary storage and to be later dispositioned in the planned VLLW facility. As of May 2015, a total of 236 m3 resulting in approximately $1.1 million in total savings have been sequestered. One of the main hurdles in implementing VLLW Sequestration is the development of process criteria. Waste Acceptance Criteria (WAC) are used as a guide or as requirements for determining whether waste is accepted by the waste management facility. Establishment of the process criteria ensures that segregated waste materials have a high likelihood to meet the VLLW WAC and be accepted into the planned VLLW facility. This paper outlines the challenges and various factors which were considered in the development of interim process criteria.

scholarly journals Near-field/Far-field Interface of a Near-Surface Low-Level Radioactive Waste Site

2003 ◽  
Vol 807 ◽  
Author(s):  
I. R. Beadle ◽  
J. Graham ◽  
S. Boult ◽  
V. L. Hand ◽  
P. Warwick ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Iron Hydroxide ◽  
Near Field ◽  
Experimental Studies ◽  
Far Field ◽  
Near Surface ◽  
Interface Zone ◽  
Low Level ◽  
Modelling Studies ◽  
Low Level Radioactive Waste

ABSTRACTExperimental and Modelling studies have been used to investigate the biogeochemical processes occurring at the interface zone between the near-field and far-field of the Drigg Low-Level radioactive Waste (LLW) trenches. These have led to a conceptual model of interface biogeochemistry, which has subsequently been modelled by the BNFL code known as the Generalised Repository Model (GRM). GRM simulations suggest that as organic rich leachate migrates into the far-field, iron III minerals such as iron hydroxide will dissolve, and reduced iron minerals such as siderite will precipitate due to microbial processes. Batch and column experimental studies have verified this conceptual understanding. Some unexpected processes, such as the presence of nitrate enhancing sulphate reduction, were also observed

Influence of the Conditional Release of the Materials With Very Low Level of Radioactivity on the Environment

2011 ◽  
Author(s):  
Slavka Prvakova ◽  
Adela Mrskova ◽  
Jozef Pritrsky
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Computer Code ◽  
Recycled Concrete ◽  
Building Structures ◽  
Conditional Release ◽  
Near Surface ◽  
Low Level ◽  
Analytical Approaches

Significant amount of solid materials (metals, non-metals, building structures) that could be contaminated or activated is produced during operation and especially decommissioning of nuclear power plants. Considerable fraction of these materials has level of radioactivity close to the radiological limits allowing its safe release into the environment thereby could be potentially recycled within the special constructions, as for example tunnels, roads or bridges. If the requirements of legislation on the radiological limits for handling such material and long-term safety of the constructions are met, contaminated material can be incorporated in the form of recycled concrete, remelted steel, etc. The paper presents implementation of the IAEA and EC recommendations into the form of detailed analytical approaches with the aim to develop integrated scenarios and to analyse long-term influence of the conditional release of the material with very low level of radioactivity on the environment. Further, an estimation of the key input parameters characteristic for the specific conditions of Slovak case in order to fulfil the radiological limits according to the Slovak legislation is included. Analysed integrated scenarios represent surface or underground civil construction with radionuclides released directly into the geosphere and transported by a groundwater flow to the biosphere. The migration of radionuclides is modelled in the near-surface conditions with the advection as a dominant transport mechanism. Computer code GoldSim is used to evaluate the long-term safety assessment of the conditionally released material on the environment.

41. Diffusion Badges as a Long-Term, Low-Level Method of Ambient Air Analysis

2005 ◽  
Author(s):  
K. Parker ◽  
S. Rose-Pehrsson ◽  
D. Kidwell
Keyword(s):  
Ambient Air ◽  
Air Analysis ◽  
Low Level ◽  
Level Method

Long-Term Unemployment in Poland in 2008-2012 - Tendencies, Structure and Selected Determinants

2013 ◽  
Vol 8 (4) ◽  
pp. 347-359
Author(s):  
Leszek Kucharski
Keyword(s):  
Secondary Education ◽  
Young People ◽  
Level Of Education ◽  
Low Level ◽  
Increased Risk

This study presents the structure and tendencies in long-term unemployment in Poland in the years 2008-2012. This study identifies the groups of people with an increased risk of long-term unemployment. The analyses produced the following conclusions. The groups with the highest risk of long-term unemployment include: singles, people aged of 55 and above and people with a low level of education. Young people with university and general secondary education faced the lowest risk of long-term unemployment. 

Sign in / Sign up

Export Citation Format

Share Document