scholarly journals Deep Borehole Disposal Safety Case

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2141 ◽  
Author(s):  
Geoff A. Freeze ◽  
Emily Stein ◽  
Patrick V. Brady ◽  
Carlos Lopez ◽  
David Sassani ◽  
...  
Keyword(s):  
Reactive Transport ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Deep Borehole ◽  
Safety Case ◽  
Key Issues ◽  
Safety Assessments ◽  
Engineered Barriers ◽  
Technical Basis ◽  
Safety Strategy

The safety case for deep borehole disposal of nuclear wastes contains a safety strategy, an assessment basis, and a safety assessment. The safety strategy includes strategies for management, siting and design, and assessment. The assessment basis considers site selection, pre-closure, and post-closure, which includes waste and engineered barriers, the geosphere/natural barriers, and the biosphere and surface environment. The safety assessment entails a pre-closure safety analysis, a post-closure performance assessment, and confidence enhancement analyses. This paper outlines the assessment basis and safety assessment aspects of a deep borehole disposal safety case. The safety case presented here is specific to deep borehole disposal of Cs and Sr capsules, but is generally applicable to other waste forms, such as spent nuclear fuel. The safety assessments for pre-closure and post-closure are briefly summarized from other sources; key issues for confidence enhancement are described in greater detail. These confidence enhancement analyses require building the technical basis for geologically old, reducing, highly saline brines at the depth of waste emplacement, and using reactive-transport codes to predict their movement in post-closure. The development and emplacement of borehole seals above the waste emplacement zone is also important to confidence enhancement.

scholarly journals Science underpinning the safety case of deep geological repositories − challenges in the past and in the future and how to maintain knowledge and competence during operation

2020 ◽  
Vol 6 ◽  
pp. 24
Author(s):  
Johan Andersson
Keyword(s):  
International Cooperation ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Research Strategy ◽  
Version Control ◽  
The Past ◽  
Safety Case ◽  
Long Time ◽  
New Challenges ◽  
New Phase

Final repositories for spent nuclear fuel are approaching implementation. A prerequisite for these advancements is that it has been shown that the repository can be constructed and operated in practice in such a way that safety can be assured both during operation and over very long time scales. The success rests on decades of structured and objective-driven research and development. A key element of the research strategy has been to ensure adequate in-house competence and expertise. Also, openness and international cooperation are essential. Workable procedures for data qualification, version control as well as internal and external peer review have gained importance. When the programmes now enter a new phase of construction and operation new challenges will arise. Even if the implementing organisations would need to keep a core competence on post closure safety assessment international cooperation will be even more important on developing, sharing and managing the knowledge needed.

scholarly journals Deep borehole disposal of intermediate-level waste

2021 ◽  
Vol 1 ◽  
pp. 263-264
Author(s):  
Dirk Mallants ◽  
John Phalen ◽  
Hef Griffiths
Keyword(s):  
Spent Nuclear Fuel ◽  
Cost Effective ◽  
Full Scale ◽  
Intermediate Level ◽  
High Level Waste ◽  
Deep Borehole ◽  
International Partnership ◽  
Geologic Disposal ◽  
Safety Assessments

Abstract. Around the world, deep borehole disposal is being evaluated for intermediate-level waste (ILW), high-level waste (HLW), spent nuclear fuel (SNF), separated plutonium waste and some very high specific activity fission product waste. In Australia, long-lived ILW from research reactors and radiopharmaceutical production represents the principal waste stream that requires deep geologic disposal. Whilst the Australian government has not yet made a decision on its preferred strategy for ILW disposal, deep borehole disposal of small volumes of ILW would be a more cost-effective and modular solution compared to a conventional geologic disposal facility (GDF). CSIRO, ANSTO and SANDIA have created an international partnership to execute a full-scale borehole research, development and demonstration (RD&D) project in Australia. The project will demonstrate the technical feasibility of the long-term safety of borehole disposal in deep geological formations. The execution of this project could also demonstrate options for nuclear waste disposal that would reduce proliferation risks, potentially up to the termination of compliance with international safeguards requirements. The RD&D includes demonstration of surface handling and waste/seal emplacement capabilities, basic research on foundational science areas, and full-scale field testing in both a deep characterization borehole and a larger-diameter (0.7 m or 27.5 inch) 2000 m deep demonstration borehole. The multi-barrier system designed for such a deep disposal borehole concept places much less reliance on engineered barriers at the disposal zone to achieve safety as compared to a conventional GDF. It rather relies on geological features for waste containment. The concept being explored uses disposal containers with primary waste packages, such as vitrified waste canisters, inside; to be both cost effective and fit for purpose, such a container could have a mild steel-based structural component with copper coating. A critical review of six coating technologies showed that cold spray has the greatest advantages, such as minimal porosity and compressive residual stress. The RD&D has delivered novel enabling tools that assist with site screening, borehole design and post-closure safety assessments. For instance, an automated geological fault mapping and meshing tool was developed that assists with ranking the suitability of potential disposal sites based on proximity to faults. New codes were developed for better representation of fault zones in 2D/3D numerical flow and transport models, while also being more efficient to execute. Post-closure safety assessments tested the sensitivity of long-term safety with respect to disposal depth, rock permeability and sorption. Heat transport calculations explored the sensitivity of temperature evolution within the borehole to parameters such as heat load, borehole depth, geothermal gradients and rock thermal conductivity. For verification of host rock tightness while also demonstrating the absence of recent groundwater, a new noble gas analytical facility has been established for measuring rare noble gases in mineral fluid inclusions as indicators of very old pore fluids.

South African Safety Assessment Framework for the Pebble Bed Modular Reactor

2008 ◽  
Author(s):  
Jean Joubert ◽  
Norbert Kohtz ◽  
Ian Coe
Keyword(s):  
South African ◽  
Safety Assessment ◽  
Assessment Process ◽  
Current Status ◽  
Pebble Bed ◽  
Formal Assessment ◽  
Safety Case ◽  
Regulatory Assessment ◽  
Safety Assessments ◽  
Assessment Activities

It is planned to construct a first of a kind Pebble Bed Modular Reactor (PBMR) in South Africa. A need has been recognized to accompany the licensing process for the PBMR with independent safety assessments to ensure that the safety case submitted by the applicant complies with the licensing requirements of the NNR. At the HTR 2006 Conference, the framework and major challenges on safety assessment that the South African National Nuclear Regulator (NNR) faces in developing and applying appropriate strategies and tools were presented. This paper discusses the current status of the various NNR assessment activities and describes how this will be considered in the NNR Final Report on the PBMR Safety Case. The traditional safety assessment process has been adapted to take into account the developmental nature of the project. By performing safety assessments, the designer and applicant must ensure that the design as proposed for construction and as-built meets the safety requirements defined by the regulatory framework. The regulator performs independent safety assessments, including independent analyses in areas deemed safety significant and potentially safety significant. The developmental nature of the project also led to the identification of a series of regulatory assessment activities preceding the formal assessment of the safety case. Besides an assessment of the resolution of Key Licensing Issues which have been defined in an early stage of the project and are discussed in /1/, these activities comprise the participation in an SAR Early Intervention Process, the execution of a regulatory HAZOP and the development of a regulatory assessment specification for the formal assessment of the safety case. This paper briefly describes these activities and their current status. During the last two years, significant progress was made with the development or adjustment of tools for the independent analysis by the regulator of the steady state core design, of the transient neutronic/thermal hydraulic behaviour of the reactor, of fission product release from the fuel elements, and of activation of fuel matrix and graphite impurities.

The SR 97 Safety Assessment of a KBS 3 Repository for Spent Nuclear Fuel – Overview, Review Comments and New Developments

2002 ◽  
Vol 713 ◽  
Author(s):  
Allan Hedin ◽  
Ulrik Kautsky ◽  
Lena Morén ◽  
Patrik Sellin ◽  
Jan-Olof Selroos
Keyword(s):  
Nuclear Fuel ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Bentonite Clay ◽  
Research Programme ◽  
High Strength ◽  
Functional Requirements ◽  
Future Evolution ◽  
Site Investigations ◽  
Potential Safety

ABSTRACTIn preparation for coming site investigations for siting of a deep repository for spent nuclear fuel, the Swedish Nuclear Fuel and Waste Management Company, SKB has carried out the longterm safety assessment SR 97, requested by the Swedish Government. The repository is of the KBS-3 type, where the fuel is placed in isolating copper canisters with a high-strength cast iron insert. The canisters are surrounded by bentonite clay in individual deposition holes at a depth of 500 m in granitic bedrock. Geological data are taken from three sites in Sweden to shed light on different conditions in Swedish granitic bedrock.The future evolution of the repository system is analysed in the form of five scenarios. The first is a base scenario where the repository is postulated to be built entirely according to specifications and where present-day conditions in the surroundings, including climate, persist. The four other scenarios show the evolution if the repository contains a few initially defective canisters, in the event of climate change, in the event of earthquakes, and in the event of future inadvertent human intrusion.The principal conclusion of the assessment is that the prospects of building a safe deep repository for spent nuclear fuel in Swedish granitic bedrock are very good. The results of the assessment also serve as a basis for formulating requirements and preferences regarding the bedrock in site investigations, for designing a programme for site investigations, for formulating functional requirements on the repository's barriers, and for prioritisation of research.SR 97 has been reviewed both by an international group of OECD/NEA experts and by Swedish authorities. The NEA reviewers concluded that “SR 97 provides a sensible illustration of the potential safety of the KBS-3 concept”, and no issues were identified that need to be resolved prior to proceeding to the investigation of potential sites. The authorities' conclusions were in principal consistent with those of the NEA.Uncertainties and lack of knowledge in different areas identified in SR 97 have strongly influenced the contents and structure of SKBs most recent research programme, RD&DProgramme 2001.Since SR 97, the methodology for probabilistic consequence analyses have been further developed. Analytic approximations to the numerical transport models used in SR 97 have been developed. The new models have been used to extend the probabilistic calculations in SR 97.

Durability of potential plutonium wasteforms under repository conditions

2012 ◽  
Vol 76 (8) ◽  
pp. 2911-2918 ◽  
Author(s):  
G. Deissmann ◽  
S. Neumeier ◽  
G. Modolo ◽  
D. Bosbach
Keyword(s):  
Chemical Reactivity ◽  
Final Decision ◽  
Geological Disposal ◽  
Aqueous Environments ◽  
Safety Case ◽  
Key Issues ◽  
The Uk ◽  
High Level ◽  
Radionuclide Release

AbstractSeparated stocks of UK civil plutonium are currently held as a zero value asset in storage, as there is no final decision about whether they should be treated as a resource for future use as nuclear fuel or as waste. Irrespective of future UK government strategies regarding plutonium, at least a portion of the UK civil plutonium inventory will be designated for geological disposal. In this context, we performed a high-level review of the performance of potential wasteforms for the disposal of separated civil plutonium. The key issues considered were the durability and chemical reactivity of the wasteforms in aqueous environments and the long-term radionuclide release under conditions relevant to geological disposal. The major findings of the review, relevant not only to the situation in the UK but to plutonium disposal in general, are summarized in this paper. The review showed that, in the event of a decision being taken to declare plutonium as a waste for disposal, more systematic studies would be required to constrain the wasteform performance under repository conditions in order to derive realistic source terms for a safety case.

Safety Assessment ofVitis vinifera(Grape)-Derived Ingredients as Used in Cosmetics

2014 ◽  
Vol 33 (3_suppl) ◽  
pp. 48S-83S ◽  
Author(s):  
Monice M. Fiume ◽  
Wilma F. Bergfeld ◽  
Donald V. Belsito ◽  
Ronald A. Hill ◽  
Curtis D. Klaassen ◽  
...  
Keyword(s):  
Vitis Vinifera ◽  
Clinical Data ◽  
Safety Assessment ◽  
Expert Panel ◽  
Cosmetic Ingredients ◽  
Safety Assessments

The Cosmetic Ingredient Review Expert Panel (Panel) assessed the safety of 24 Vitis vinifera (grape)-derived ingredients and found them safe in the present practices of use and concentration in cosmetics. These ingredients function in cosmetics mostly as skin-conditioning agents, but some function as antioxidants, flavoring agents, and/or colorants. The Panel reviewed the available animal and clinical data to determine the safety of these ingredients. Additionally, some constituents of grapes have been assessed previously for safety as cosmetic ingredients by the Panel, and others are compounds that have been discussed in previous Panel safety assessments.

scholarly journals Reactive transport calculations to evaluate sulphide fluxes in the near-field of a SF/HLW repository

2019 ◽  
Vol 98 ◽  
pp. 10005
Author(s):  
Marek Pękala ◽  
Paul Wersin ◽  
Veerle Cloet ◽  
Nikitas Diomidis
Keyword(s):  
Reactive Transport ◽  
Spent Nuclear Fuel ◽  
Near Field ◽  
Opalinus Clay ◽  
High Level Waste ◽  
Waste Containment ◽  
Geological Repository ◽  
High Level ◽  
Reducing Bacteria ◽  
Hlw Repository

Radioactive waste is planned to be disposed in a deep geological repository in the Opalinus Clay (OPA) rock formation in Switzerland. Cu coating of the steel disposal canister is considered as potential a measure to ensure complete waste containment of spent nuclear fuel (SF) and vitrified high-level waste (HLW) or a period of 100,000 years. Sulphide is a potential corroding agent to Cu under reducing redox conditions. Background dissolved sulphide concentrations in pristine OPA are low, likely controlled by equilibrium with pyrite. At such concentrations, sulphide-assisted corrosion of Cu would be negligible. However, the possibility exists that sulphate reducing bacteria (SRB) might thrive at discrete locations of the repository’s near-field. The activity of SRB might then lead to significantly higher dissolved sulphide concentrations. The objective of this work is to employ reactive transport calculations to evaluate sulphide fluxes in the near-field of the SF/HLW repository in the OPA. Cu canister corrosion due to sulphide fluxes is also simplistically evaluated.

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