Moving HLW-EBS Concepts into the 21st Century

2000 ◽  
Vol 663 ◽  
Author(s):  
I.G. McKinley ◽  
H. Kawamura ◽  
H. Tsuchi
Keyword(s):  
Quality Assurance ◽  
21St Century ◽  
Host Rock ◽  
Industrial Scale ◽  
High Level Waste ◽  
Safety Case ◽  
Engineered Barrier ◽  
High Level

ABSTRACTMost national high-level waste (HLW) disposal programs actually reflect, or are based on, concepts which were developed during the '70s or early '80s. Although suitable for demonstration of concept feasibility, designs of the engineered barrier system (EBS) do not take into account the tremendous developments in system understanding and materials technology over the last two decades, the practicality (and cost) of their quality assurance and implementation on an industrial scale and the transparency of the demonstration of the safety case. In many ways, due to the increased significance of popular acceptance over the last decade, the last point may be of particular relevance.This paper reviews the work already carried out on “2nd generation” concepts and extends this to identify the key attributes of an ideal design for the specific case of disposal of vitrified HLW from reprocessing in a “wet” host rock (either crystalline or sedimentary). Based on the concept developed, key R&D requirements are identified.

The Role of Large Scale Demonstration Experiments in Supporting the Implementation of a High Level Waste Programme

2013 ◽  
Author(s):  
K. Yoshimura ◽  
I. Gaus ◽  
K. Kaku ◽  
T. Sakaki ◽  
A. Deguchi ◽  
...  
Keyword(s):  
Host Rock ◽  
Large Scale ◽  
International Workshop ◽  
Lessons Learned ◽  
High Level Waste ◽  
License Application ◽  
Safety Case ◽  
And Performance ◽  
Research Organisations ◽  
High Level

Large scale demonstration experiments in underground research laboratories (both onsite and off-site) are currently undertaken by most high level radioactive waste management organisations. The decision to plan and implement prototype experiments, which might have a life of several decades, has both important strategic and budgetary consequences for the organisation. Careful definition of experimental objectives based on the design and safety requirements is critical. The implementation requires the involvement of many parties and needs flexible but consequent management as, for example, additional goals for the experiments, identified in the course of the implementation, might jeopardise initial primary goals. The outcomes of an international workshop in which European and Japanese implementers (SKB, Posiva, Andra, ONDRAF, NUMO and Nagra) but also certain research organisations (JAEA, RWMC) participated identified which experiments are likely to be needed depending on the progress in implementing a disposal programme. Already earlier in a programme, large scale demonstrations are generally performed aiming at reducing uncertainties identified during the safety case development such as thermo-hydraulic-mechanical process validation in the engineered barrier system and target host rock. Also feasibility testing of underground construction in a potential host rock at relevant depth might be required. Later in a programme, i.e., closer to the license application, large scale experiments aim largely at demonstrating engineering feasibility and performance confirmation of complete repository components. Ultimately, before licensing repository operation, 1:1 scale commissioning testing will be required. Factors contributing to the successful completion of large scale demonstration experiments in terms of planning, defining the objectives, optimising results and main lessons learned over the last 30 years are being discussed. The need for international coordination in defining the objectives of new large scale demonstration experiments is addressed. The paper is expected to provide guidance to implementing organisations (especially those in their early stages of the programme), considering participating in and/or or conducting on their own large scale experiments in the near future.

An Approach to Analysis of High Level waste Container Performance in an Unsaturated Repository Environment

1993 ◽  
Vol 333 ◽  
Author(s):  
John C. Walton ◽  
Narasi Sridhar ◽  
Gustavo Cragnolino ◽  
Tony Torng ◽  
Prasad Nair
Keyword(s):  
Dominant Role ◽  
Near Field ◽  
Temperature Fields ◽  
Localized Corrosion ◽  
High Level Waste ◽  
Quantitative Methodology ◽  
Waste Container ◽  
Wide Range ◽  
Engineered Barrier ◽  
High Level

ABSTRACTOne of the requirements for the performance of waste packages prescribed in 10CFR 60.113 is that the high level waste must be “substantially completely” contained for a minimum period of 300 to 1000 years. During this period, the radiation and thermal conditions in the engineered barrier system and the near-field environment are dominated by fission product decay. In the present U.S design of the engineered barrier system, the outer container plays a dominant role in maintaining radionuclide containment. A quantitative methodology for analyzing the performance of the container is described in this paper. This methodology enables prediction of the evolution of the waste package environment in terms of temperature fields, stability of liquid water on the container surface, and concentration of aggressive ions such as chloride. The initiation and propagation of localized corrosion is determined by the corrosion potential of the container material and critical potentials for localized corrosion. The coiTOsion potential is estimated from the kinetics of the anodic and cathodic reactions including oxygen diffusion through scale layers formed on the container surface. The methodology described is applicable to a wide range of metals, alloys and environmental conditions.

Evolution of Chemistry and Its Effects on the Corrosion of Engineered Barrier Materials

2006 ◽  
Vol 985 ◽  
Author(s):  
Darrell Dunn ◽  
Yi-Ming Pan ◽  
Xihua He ◽  
Lietai Yang ◽  
Roberto Pabalan
Keyword(s):  
Environmental Conditions ◽  
Environmental Influence ◽  
Near Field ◽  
Yucca Mountain ◽  
High Level Waste ◽  
Seepage Water ◽  
Waste Package ◽  
Barrier Materials ◽  
Engineered Barrier ◽  
High Level

ABSTRACTThe evolution of environmental conditions within the emplacement drifts of a potential high-level waste repository at Yucca Mountain, Nevada, may be influenced by several factors, including the temperature and relative humidity within the emplacement drifts and the composition of seepage water. The performance of the waste package and the drip shield may be affected by the evolution of the environmental conditions within the emplacement drifts. In this study, tests evaluated the evolution of environmental conditions on the waste package surfaces and in the surrounding host rock. The tests were designed to (i) simulate the conditions expected within the emplacement drifts; (ii) measure the changes in near-field chemistry; and (iii) determine environmental influence on the performance of the engineered barrier materials. Results of tests conducted in this study indicate the composition of salt deposits was consistent with the initial dilute water chemistry. Salts and possibly concentrated calcium chloride brines may be more aggressive than either neutral or alkaline brines.

scholarly journals Feasibility of using a high-level waste canister as an engineered barrier in disposal

1982 ◽  
Author(s):  
S.C. Slate ◽  
S.G. Pitman ◽  
J.F. Nesbitt ◽  
W.L. Partain
Keyword(s):  
High Level Waste ◽  
Engineered Barrier ◽  
High Level

Assessing the durability of nuclear glass with respect to silica controlling processes in a clayey underground disposal

2006 ◽  
Vol 932 ◽  
Author(s):  
Laurent De Windt ◽  
Stéphanie Leclercq ◽  
Jan van der Lee
Keyword(s):  
Host Rock ◽  
Reactive Transport ◽  
Transport Model ◽  
Glass Block ◽  
High Level Waste ◽  
Residual Rate ◽  
Glass Dissolution ◽  
Underground Disposal ◽  
High Level

ABSTRACTThe long-term behaviour of vitrified high-level waste in an underground clay repository was assessed by using the reactive transport model HYTEC with respect to silica diffusion, sorption and precipitation processes. Special attention was given to the chemical interactions between glass, corroded steel and the host-rock considering realistic time scale and repository design. A kinetic and congruent dissolution law of R7T7 nuclear glass was used assuming a first-order dissolution rate, which is chemistry dependent, as well as a long-term residual rate. Without silica sorption and precipitation, glass dissolution is diffusion-driven and the fraction of altered glass after 100,000 years ranges from 5% to 50% depending on the fracturation degree of the glass block. Corrosion products may limit glass dissolution by controlling silica diffusion, whereas silica sorption on such products has almost no effect on glass durability. Within the clayey host-rock, precipitation of silicate minerals such as chalcedony may affect glass durability much more significantly than sorption. In that case, however, a concomitant porosity drop is predicted that could progressively reduce silica diffusion and subsequent glass alteration.

Study of the Performance of Sealing Systems for Access Shafts in a High-Level Waste Repository

1992 ◽  
Vol 294 ◽  
Author(s):  
A. Saotome ◽  
K. Hara ◽  
J. Okamoto
Keyword(s):  
Host Rock ◽  
Ground Surface ◽  
Sensitivity Analyses ◽  
High Level Waste ◽  
Radionuclide Transport ◽  
Radionuclide Migration ◽  
Backfill Material ◽  
Disturbed Zone ◽  
Waste Repository ◽  
High Level

ABSTRACTShaft sealing in a high-level waste(HLW) disposal system functions to minimize the water flow passage, and retard the radionuclide transport from the repository to the accessible environment. It is important to estimate the radionuclide migration along the sealed shaft from the viewpoint of the design and the performance assessment of the sealing system.This study presents the results of sensitivity analyses on the radionuclide migration in the vicinity of the access shaft of a repository in order to evaluate the effects of the length of a plug, as well as the number of plugs, and curtain grouts.In this study, the upward hydraulic gradient of the groundwater flow along shafts was used, based on transient coupled thermo-hydraulic analyses around a repository. Hydraulic conductivities of the backfill material and the disturbed zones around the shaft tunnels were also assumed to be one order and two orders of magnitude higher than that of the host rock, respectively.The results show that the velocity of the groundwater within the shaft and the disturbed zone is reduced by a factor of one third by installing a few plugs into the shaft filled with backfill material. The curtain grouts have the effect of retarding the radionuclide migration from the repository to the ground surface at a factor of approximately five. A few plug installations have the same effect. The sealing system properly constituted with backfill, plugs, and grouts can provide the same performance as the original host rock.

Project Opalinus Clay (Entsorgungsnachweis) - Illustrating the Safety and Robustness of the Proposed Disposal System for SF, HLW and Long-lived ILW

2003 ◽  
Vol 807 ◽  
Author(s):  
L. H. Johnson ◽  
J. W. Schneider ◽  
Piet Zuidema ◽  
P. Gribi ◽  
G. Mayer ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Host Rock ◽  
Opalinus Clay ◽  
High Level Waste ◽  
Spent Fuel ◽  
Northern Switzerland ◽  
High Level ◽  
National Cooperative

ABSTRACTNagra (the Swiss National Cooperative for the Disposal of Radioactive Waste) has completed a study to determine the suitability of Opalinus Clay as a host rock for a repository for spent fuel (SF), high-level waste from reprocessing (HLW) and long-livedintermediate-level waste (ILW). The proposed siting area is in the Zürcher Weinland region of Northern Switzerland. A repository at this site is shown to provide sufficient safety for a spectrum of assessment cases that is broad enough to cover all reasonable possibilities for the evolution of the system. Furthermore, the system is robust; i.e. remaining uncertainties do not put safety in question.

Geological Repository for Nuclear High Level Waste in France From Feasibility to Design Within a Legal Framework

2007 ◽  
Author(s):  
Patrice Voizard ◽  
Stefan Mayer ◽  
Gerald Ouzounian
Keyword(s):  
Host Rock ◽  
Legal Framework ◽  
High Level Waste ◽  
National Review ◽  
Review Team ◽  
Geological Repository ◽  
Underground Disposal ◽  
High Level ◽  
Underground Research Laboratory ◽  
Future Work

Over the past 15 years, the French program on deep geologic disposal of high level and long-lived radioactive waste has benefited from a clear legal framework as the result of the December 30, 1991 French Waste Act. To fulfil its obligations stipulated in this law, Andra has submitted the “Dossier 2005 Argile” (clay) and “Dossier 2005 Granite” to the French Government. The first of those reports presents a concept for the underground disposal of nuclear waste at a specific clay site and focuses on a feasibility study. Knowledge of the host rock characteristics is based on the investigations carried out at the Meuse/Haute Marne Underground Research Laboratory. The repository concept addresses various issues, the most important of which relates to the large amount of waste, the clay host rock and the reversibility requirement. This phase has ended upon review and evaluation of the “Dossier 2005” made by different organisations including the National Review Board, the National Safety Authority and the NEA International Review Team. By passing the “new”, June 28, 2006 Planning Act on the sustainable management of radioactive materials and waste, the French parliament has further defined a clear legal framework for future work. This June 28 Planning Act thus sets a schedule and defines the objectives for the next phase of repository design in requesting the submission of a construction authorization application by 2015. The law calls for the repository program to be in a position to commission disposal installations by 2025.

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