Securitized Citizens

Nagra, Baljit

doi:10.3138/9781442624467

Cited by 25 publications

(27 citation statements)

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“…Strontium isotopes were also analysed in anhydrite nodules and in Hauptmuschelkalk limestones containing <50 vol% dolomite. The limestones show 87 Sr/ 86 Sr ratios slightly higher than that of Middle Triassic seawater, in agreement with previous studies (Nagra, 2001;Ufrecht & H€ olzl, 2006). Primary and diagenetic anhydrite nodules show similar 87 Sr/ 86 Sr ratios to the dolomites surrounding them, including the increase in values with depth (Table 2; Fig.…”

Section: Strontium Isotopessupporting

confidence: 92%

Dolomitization by hypersaline reflux into dense groundwaters as revealed by vertical trends in strontium and oxygen isotopes: Upper Muschelkalk, Switzerland

2018

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The Trigonodus Dolomit is the dolomitized portion of the homoclinal ramp sediments of the Middle Triassic Upper Muschelkalk in the south‐east Central European Basin. Various dolomitizing mechanisms, followed by recrystallization, have been previously invoked to explain the low δ18O, high 87Sr/86Sr, extensive spatial distribution and early nature of the replacive matrix dolomites. This study re‐evaluates the origin, timing and characteristics of the dolomitizing fluids by examining petrographic and isotopic trends in the Trigonodus Dolomit at 11 boreholes in northern Switzerland. In each borehole the ca 30 m thick unit displays the same vertical trends with increasing depth: crystal size increase, change from anhedral to euhedral textures, ultraviolet‐fluorescence decrease, δ18OVPDB decrease from −1·0‰ at the top to −6·7‰ at the base and an 87Sr/86Sr increase from 0·7080 at the top to 0·7117 at the base. Thus, dolomites at the top of the unit record isotopic values similar to Middle Triassic seawater (δ18OVSMOW = 0‰; 87Sr/86Sr = 0·70775) while dolomites at the base record values similar to meteoric groundwaters from the nearby Vindelician High (δ18OVSMOW = −4·0‰; 87Sr/86Sr = >0·712). According to water–rock interaction modelling, a single dolomitizing or recrystallizing fluid cannot have produced the observed isotopic trends. Instead, the combined isotopic, geochemical and petrographic data can be explained by dolomitization via seepage‐reflux of hypersaline brines into dense, horizontally‐advecting groundwaters that already had negative δ18O and high 87Sr/86Sr values. Evidence for the early groundwaters is found in meteoric calcite cements that preceded dolomitization and in fully recrystallized dolomites with isotopic characteristics identical to the groundwaters following matrix dolomitization. This study demonstrates that early groundwaters can play a decisive role in the formation and recrystallization of massive dolomites and that the isotopic and textural signatures of pre‐existing groundwaters can be preserved during seepage‐reflux dolomitization in low‐angle carbonate ramps.

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Section: Strontium Isotopessupporting

confidence: 92%

Dolomitization by hypersaline reflux into dense groundwaters as revealed by vertical trends in strontium and oxygen isotopes: Upper Muschelkalk, Switzerland

2018

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“…It is noted that radiation fields in the repository will decrease over time with the decay of relatively short-lived isotopes such as 60 Co. Model calculations for a Swiss ILW (intermediate-level waste) repository consider a time frame of 1000 years to be sufficient to reduce the beta and gamma activity by a factor of 100 (Nagra 2002). Thus any effect of self-irradiation and radiolysis on steel corrosion rates would be limited to relatively short post-closure timescales, relative to safety assessment timescales.…”

Section: Discussionmentioning

confidence: 99%

Release and speciation of¹⁴C during the corrosion of activated steel in deep geological repositories for the disposal of radioactive waste

et al. 2018

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Carbon-14 (radiocarbon,14C) is an important radionuclide in the inventory of radioactive waste in many disposal programs due to its significant dose contributions in safety assessments for geological repositories. Activated steels from nuclear reactors are one of the major sources of14C. Knowledge of14C release from steel wastes and its chemical form (speciation) is limited giving rise to uncertainty regarding the fate of14C and a conservative treatment in assessment calculations. In this work, we summarize and make a synthesis of selected results from Work Package 2 of the EU CAST project aiming to improve understanding of14C release related to steel corrosion under repository-relevant conditions. The outcome of the experiments is discussed in the context of the long-term evolution of a repository and its potential consequences for safety assessment.

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“…These include Project Gewähr (L/ILW & HLW, Nagra, 1985), the Wellenberg Project (L/ILW, Nagra, 1994), Project Opalinus Clay (HLW, Nagra, 2002aNagra, , 2002b, and recent project work needed in the context of the Swiss site selection process (L/ILW & HLW, Nagra, 2008aNagra, , 2008bNagra, , 2008cNagra, , 2010.…”

Section: Nea/rwm/r(2013)9mentioning

confidence: 99%

“…1 The Sectoral Plan defines three stages for site selection, the first of which was completed in 2011. For Stage 1 Nagra proposed in 2008 three siting regions for the HLW repository and six siting regions for the L/ILW repository (three of them overlapping with the siting regions for the HLW repository) (Nagra, 2008a). After a careful review by the responsible authorities and a broad consultation process, the Swiss Federal Council agreed in November 2011 to the siting regions proposed by Nagra.…”

Section: Introduction and Overviewmentioning

confidence: 99%

Analysis of mineralogical and deformation-induced transformations of Nizhnekansky Massif rocks to estimate their retention capacity in geological disposal and isolation of radioactive waste

Петров¹,

Poluektov²,

Hammer³

et al. 2015

gzh

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JT03354141Complete document available on OLIS in its original format This document and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area. . Since then, there have been major developments in a number of national geological disposal programmes and significant experience has been obtained in preparing and reviewing cases for the operational and long-term safety of proposed and operating geological repositories. Especially, three national programmes are now, or will shortly be, at the stage of licence application for a deep geological repository for the disposal of spent nuclear fuel or high-level and other long-lived radioactive waste.Thus, the purpose of this Symposium, "The Safety Case for Deep Geological Disposal of Radioactive Waste: 2013 State of the Art", was to assess the practice, understanding and roles of the safety case, as applied internationally at all stages of repository development, including the interplay of technical, regulatory and societal issues, as they have developed since 2007.The Symposium was organised and hosted by the Nuclear Energy Agency (NEA) of the Organisation for Economic Co-operation and Development (OECD), and co-sponsored by the EC and the IAEA.The 2013 Symposium attracted 168 participants from 65 organisations and 17 countries and international bodies.The Symposium was chaired by Klaus-Jürgen Röhlig, who is also the Chair of the NEA Integration Group for the Safety Case (IGSC). The planning and implementation of the symposium were supported by the efforts of staff of the NEA and of the programme committee.This synopsis was drafted by Trevor Sumerling (Safety Assessment Management Ltd, UK), finalised under the direction of the Chair and Gloria Kwong of the NEA and approved by the programme committee. Deep Geological Repositories (1999). Since then the concept has been elaborated on in NEA documents describing the nature and purpose of safety cases , 2013a and has been the basis of NEA/IGSC collaborative projects and EU projects (EC, 2011). The concept has been taken up in international safety standards as promulgated by the IAEA (2006, 2011) and recently in ICRP recommendations on the application of the system of radiological protection to geological disposal (ICRP, 2013).Meanwhile, the concept has been developed practically and applied within many national radioactive waste disposal programmes and also taken up in some national regulatory guides. The NEA has used the concept as a guide in several international peer reviews of national repository programmes and safety documentation. In Europe, the EU Directive 2011/70/Euratom (EU, 2011) establishes a framework to ensure responsible and safe management of spent fuel and radioactive waste by member states that, inter alia, requires a decision-making process based on safety evidence and arguments that mirrors the safety case concept. Aims of the symposiumThe purpose of thi...

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Securitized Citizens

Cited by 25 publications

References 0 publications

Dolomitization by hypersaline reflux into dense groundwaters as revealed by vertical trends in strontium and oxygen isotopes: Upper Muschelkalk, Switzerland

Dolomitization by hypersaline reflux into dense groundwaters as revealed by vertical trends in strontium and oxygen isotopes: Upper Muschelkalk, Switzerland

Release and speciation of¹⁴C during the corrosion of activated steel in deep geological repositories for the disposal of radioactive waste

Analysis of mineralogical and deformation-induced transformations of Nizhnekansky Massif rocks to estimate their retention capacity in geological disposal and isolation of radioactive waste

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Securitized Citizens

Cited by 25 publications

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Dolomitization by hypersaline reflux into dense groundwaters as revealed by vertical trends in strontium and oxygen isotopes: Upper Muschelkalk, Switzerland

Dolomitization by hypersaline reflux into dense groundwaters as revealed by vertical trends in strontium and oxygen isotopes: Upper Muschelkalk, Switzerland

Release and speciation of14C during the corrosion of activated steel in deep geological repositories for the disposal of radioactive waste

Analysis of mineralogical and deformation-induced transformations of Nizhnekansky Massif rocks to estimate their retention capacity in geological disposal and isolation of radioactive waste

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Release and speciation of¹⁴C during the corrosion of activated steel in deep geological repositories for the disposal of radioactive waste