Archaeological analogues for assessing the long-term performance of a mined geologic repository for high-level radioactive waste

2000 ◽  
Author(s):  
John S. Stuckless
Keyword(s):  
Radioactive Waste ◽  
Geologic Repository ◽  
High Level Radioactive Waste ◽  
High Level ◽  
Long Term Performance ◽  
Term Performance

scholarly journals Preliminary Performance Assessment for Deep Borehole Disposal of High-Level Radioactive Waste

2012 ◽  
Vol 1475 ◽  
Author(s):  
Peter N. Swift ◽  
Bill W. Arnold ◽  
Patrick V. Brady ◽  
Geoff Freeze ◽  
Teklu Hadgu ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Performance Assessment ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
High Level Radioactive Waste ◽  
Deep Boreholes ◽  
High Level ◽  
Long Term Performance ◽  
Term Performance

ABSTRACTDeep boreholes have been proposed for many decades as an option for permanent disposal of high-level radioactive waste and spent nuclear fuel. Disposal concepts are straightforward, and generally call for drilling boreholes to a depth of four to five kilometers (or more) into crystalline basement rocks. Waste is placed in the lower portion of the hole, and the upper several kilometers of the hole are sealed to provide effective isolation from the biosphere. The potential for excellent long-term performance has been recognized in many previous studies. This paper reports updated results of what is believed to be the first quantitative analysis of releases from a hypothetical disposal borehole repository using the same performance assessment methodology applied to mined geologic repositories for high-level radioactive waste. Analyses begin with a preliminary consideration of a comprehensive list of potentially relevant features, events, and processes (FEPs) and the identification of those FEPs that appear to be most likely to affect long-term performance in deep boreholes. The release pathway selected for preliminary performance assessment modeling is thermally-driven flow and radionuclide transport upwards from the emplacement zone through the borehole seals or the surrounding annulus of disturbed rock. Estimated radionuclide releases from deep borehole disposal of spent nuclear fuel, and the annual radiation doses to hypothetical future humans associated with those releases, are extremely small, indicating that deep boreholes may be a viable alternative to mined repositories for disposal of both high-level radioactive waste and spent nuclear fuel.

The Importance of Variables and Parameters in Radiolytic Chemical Kinetics Modeling

1988 ◽  
Vol 127 ◽  
Author(s):  
M. G. Piepho ◽  
P. J. Turner ◽  
P. W. Reimus
Keyword(s):  
Chemical Kinetics ◽  
Rate Constants ◽  
Transient Species ◽  
Geologic Repository ◽  
Species Concentration ◽  
Waste Package ◽  
Long Term Performance ◽  
Term Performance ◽  
Over Time

ABSTRACTRadiolysis may significantly affect the long-term performance of nuclear waste packages in a geologic repository. Radiolysis of available moisture and air in an unsaturated or saturated environment will create transient species that can significantly change the pH and/or Eh of the available moisture. These changes can influence rates of containment corrosion, waste form dissolution, and radionuclide solubilities and transport.Many of the pertinent radiochemical reactions are not completely understood, and most of the associated rate constants are poorly characterized. To help identify the important radiochemical reactions, rate constants, species, and environmental conditions, an importance theory code, SWATS (Sensitivity With Adjoint Theory-Sparse version)-LOOPCHEM, has been developed for the radiolytic chemical kinetics model in the radiolysis code LOOPCHEM. The LOOPCHEM code calculates the concentrations of various species in a radiolytic field over time. The SWATS-LOOPCHEM code efficiently calculates: 1) the importance (relative to a defined response of interest) of each species concentration over time, 2) the sensitivity of each parameter of interest, and 3) the importance of each equation in the radiolysis model. The calculated results will be used to guide future experimental and modeling work for determining the importance of radiolysis on waste package performance. A demonstration (the importance of selected concentrations and the sensitivities of selected parameters) of the SWATS-LOOPCHEM code is provided for illustrative purposes, and no attempt is made at this time to interpret the results for waste package performance assessment purposes.

Significance of long-term climate evolution and associated impacts on the long-term safety of a high-level radioactive waste repository within the German siting process

2021 ◽  
Author(s):  
Marc Wengler ◽  
Astrid Göbel ◽  
Eva-Maria Hoyer ◽  
Axel Liebscher ◽  
Sönke Reiche ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Phase 1 ◽  
High Level Radioactive Waste ◽  
Safety Requirements ◽  
Climate Evolution ◽  
Safety Assessments ◽  
High Level ◽  
Host Rocks

<p>According to the 'Act on the Organizational Restructuring in the Field of Radioactive Waste Disposal' the BGE was established in 2016. The amended 'Repository Site Selection Act' (StandAG) came into force in July 2017 and forms the base for the site selection by clearly defining the procedure. According to the StandAG the BGE implements the participative, science-based, transparent, self-questioning and learning procedure with the overarching aim to identify the site for a high-level radioactive waste (HLW) repository in a deep geological formation with best possible safety conditions for a period of one million years.</p><p>The German site selection procedure consists of three phases, of which Phase 1 is divided into two steps. Starting with a blanc map of Germany, the BGE completed Step 1 in September 2020 and identified 90 individual sub-areas that provide favorable geological conditions for the safe disposal of HLW in the legally considered host rocks; rock salt, clay and crystalline rock. Based on the results of Step 1, the on-going Step 2 will narrow down these sub-areas to siting regions for surface exploration within Phase 2 (§ 14 StandAG). Central to the siting process are representative (Phase 1), evolved (Phase 2) and comprehensive (Phase 3) preliminary safety assessments according to § 27 StandAG.</p><p>The ordinances on 'Safety Requirements' and 'Preliminary Safety Assessments' for the disposal of high-level radioactive waste from October 2020 regulate the implementation of the preliminary safety assessments within the different phases of the siting process. Section 2 of the 'Safety Requirements' ordinance provides requirements to evaluate the long-term safety of the repository system; amongst others, it states that all potential effects that may affect the long-term safety of the repository system need to be systematically identified, described and evaluated as “expected” or “divergent” evolutions. Additionally, the ordinance on 'Preliminary Safety Assessments' states in § 7, amongst others, that the geoscientific long-term prediction is a tool to identify and to evaluate geogenic processes and to infer “expected” and “divergent” evolutions from those. Hence, considering the time period of one million years for the safe disposal of the HLW and the legal requirements, it is essential to include long-term climate evolution in the German site selection process to evaluate the impact of various climate-related scenarios on the safety of the whole repository system.</p><p>To better understand and evaluate the influence of climate-related processes on the long-term safety of a HLW repository, climate-related research will be a part of the BGE research agenda. Potential research needs may address i) processes occurring on glacial – interglacial timescales (e.g. the inception of the next glaciation, formation and depth of permafrost, glacial troughs, sub-glacial channels, sea-level rise, orbital forcing) and their future evolutions, ii) effects on the host rocks and the barrier system(s) as well as iii) the uncertainties related to these effects but also to general climate models and predictions.</p>

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.

Adsorption of actinides within speleothems

2016 ◽  
Vol 80 (5) ◽  
pp. 765-780 ◽  
Author(s):  
P. Sengupta ◽  
J. Sanwal ◽  
N. L. Dudwadkar ◽  
S. C. Tripathi ◽  
P. M. Gandhi
Keyword(s):  
Valence State ◽  
Experimental Studies ◽  
Distribution Coefficients ◽  
Nuclear Wastes ◽  
Lesser Himalayas ◽  
Safety Assessments ◽  
High Level ◽  
Long Term Performance ◽  
Term Performance

AbstractStalagmites and stalactites, as observed within natural caves, may develop inside geological repositories during constructional and post-operational periods. It is therefore important to understand actinide sorption within such materials. Towards this, experimental studies were carried out with 233U, 238Np (VI), 238Np (IV), 239Pu and 241Am radiotracers using natural speleothem samples collected from the Dharamjali cave of the Kumaon Lesser Himalayas, India. Petrological/mineralogical studies showed that natural speleothems have three general domains: (1) columnar calcite; (2) microcrystalline calcite; and (3) botryoidal aragonite – each with ferruginous materials. Results showed that all domains of speleothems can take up >99% actinides, irrespective of valence state and pH (1–6 range) of the solution. However, distribution coefficients were found to be at a maximum in aragonite for most of the actinides. Such data are very important for long-term performance and safety assessments of the deep geological repositories planned for the disposal of high-level nuclear wastes.

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