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

Radiocarbon ◽  
2018 ◽  
Vol 60 (6) ◽  
pp. 1657-1670 ◽  
Author(s):  
J Mibus ◽  
N Diomidis ◽  
E Wieland ◽  
S W Swanton
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Nuclear Reactors ◽  
Steel Corrosion ◽  
Work Package ◽  
Carbon 14 ◽  
Term Evolution ◽  
Safety Assessments ◽  
The Eu

ABSTRACTCarbon-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.

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>

Characterization and Assessment of the Groundwater Pathway for the Low Level Waste Repository, UK

2011 ◽  
Author(s):  
Lee J. Hartley ◽  
Martin James ◽  
Peter Jackson ◽  
Matt Couch ◽  
John Shevelan
Keyword(s):  
Radioactive Waste ◽  
Groundwater Flow ◽  
Environmental Safety ◽  
Long Term Evolution ◽  
Low Level ◽  
Term Evolution ◽  
Groundwater Flow Modelling ◽  
Safety Case ◽  
Waste Repository

The Low Level Waste Repository (LLWR) is the UK’s principal facility for the disposal of solid low-level radioactive waste and is operated by LLW Repository Limited. Presently, LLWR Ltd is establishing the long-term environmental safety of disposals of solid radioactive waste at the LLWR, through the submission of the 2011 Environmental Safety Case for the LLWR. This Environmental Safety Case addresses the Environment Agency Guidance on Requirements for Authorisation. Aspects of the submission consider improved vault design, closure design, and quantitative assessments. Each of these issues requires an understanding of the movement of water through the facility and the surrounding geology during operations and following facility closure. Groundwater flow modelling has been used extensively in support of the interpretation of field investigations, the development of the engineering design, and an assessment of the groundwater pathway as one of the major pathways by which contaminants may reach the environment. This paper describes these important aspects of the Environmental Safety Case. The geological environment in the region of the LLWR consists of Quaternary age deposits overlying older bedrock. The facility involves shallow excavations into the Quaternary deposits, originally for trenches, with disposals to a vault system beginning in 1988. In the post-closure phase these disposals are covered by a cap and surrounded by a cut-off wall to minimise the water flow around or through the waste. An innovative modelling methodology has been developed to represent the range of scales that have to be considered from the regional groundwater flow patterns over several kilometres, the scale of tens of metres around the immediate site area, and down to about 1 metre for details of flows within the repository itself in three dimensions. Detailed finite-element models of the flow through geological media and the engineered features are used to interpret site data and assess a credible set of post-closure situations and model cases. In the radiological assessment, a more simplified compartment model is used to assess uncertainties in hydrogeological properties and the long-term evolution of the engineered barriers. Together the approach provides flexible tools for understanding and assessing a comprehensive range of aspects including details of flows within the repository, dilution and migration in the external geology, the long-term evolution of the hydrogeological system, the implications of spatial variability and alternative geological models, and effects of uncertainties.

Recent IAEA Activities in Support of Safety Assessment Capabilities

2006 ◽  
Author(s):  
S. Michael Modro ◽  
Mamdouh El-Shanawany ◽  
Sukho Lee
Keyword(s):  
Safety Assessment ◽  
Nuclear Energy ◽  
Assessment Tools ◽  
Energy Agency ◽  
Member States ◽  
Safety Standards ◽  
Computational Fluid Dynamics Cfd ◽  
Safety Assessments

One of the key missions of the International Atomic Energy Agency (IAEA) is to develop nuclear safety standards and, based on these standards, to promote the achievement and maintenance of high levels of safety in the applications of nuclear energy. In the context of this mission the IAEA conducts programmes that support the safety assessment capabilities of its Member States. This paper focuses on two new long term technical activities specific to safety assessment. These concern the issue of uncertainties in deterministic evaluation of safety, and the role of computational fluid dynamics (CFD) methods in safety assessments. In addition, a new IAEA initiative involving the collaboration of Member States in the area of advanced safety assessment tools is presented.

Long-Term Safety Assessment of a (Near-Surface) Short-Lived Radioactive Waste Repository in Lithuania

2008 ◽  
Vol 161 (2) ◽  
pp. 156-168 ◽  
Author(s):  
J. Mazeika ◽  
R. Petrosius ◽  
V. Jakimaviciute-Maseliene ◽  
D. Baltrunas ◽  
K. Mazeika ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Near Surface ◽  
Radioactive Waste Repository ◽  
Waste Repository

Long-term safety of the extended SFR - Methodology and conclusions from the SR-PSU project

MRS Advances ◽  
2016 ◽  
Vol 1 (61) ◽  
pp. 4075-4080
Author(s):  
Fredrik Vahlund
Keyword(s):  
Radioactive Waste ◽  
Nuclear Fuel ◽  
Nuclear Power ◽  
Safety Assessment ◽  
Power Plants ◽  
Spent Nuclear Fuel ◽  
Surface System ◽  
Radiological Safety ◽  
The Impact

ABSTRACTSince 1988 the Swedish Nuclear Fuel and Waste Management Co. operates a repository for low- and intermediate-level short-lived radioactive waste, SFR, in Forsmark, Sweden. Due to decommissioning of the nuclear power plants additional storage capacity is needed. In December 2014, an application to extend the repository was therefore submitted. One key component of this application was an assessment of post-closure safety of the extended SFR. For this safety assessment, a methodology based on that developed by SKB for the spent nuclear fuel repository was used and the impact of the degradation of repository components, the evolution of the surface system and changes of future climate on the radiological safety of the repository was assessed over a period of 100,000 years. The central conclusion of the SR-PSU safety assessment is that the extended SFR repository meets requirements on protection of human health and of the environment that have been established by the Swedish radiation safety authority for the final disposal of radioactive waste. Furthermore, the design of the repository was shown suitable for the waste selected and the applied methodology suitable for the safety assessment.

scholarly journals Investigating the contribution of claystone to the swelling pressure of its mixture with bentonite

2020 ◽  
Vol 195 ◽  
pp. 03043
Author(s):  
Zhixiong Zeng ◽  
Yu-Jun Cui ◽  
Nathalie Conil ◽  
Jean Talandier
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Swelling Pressure ◽  
Radioactive Waste Disposal ◽  
Inert Material ◽  
Dry Density ◽  
Test Results ◽  
Pressure Tests ◽  
Volume Swelling

Compacted MX80 bentonite/Callovo-Oxfordian (COx) claystone mixture has been considered as a possible sealing/backfilling material in the French deep geological radioactive waste disposal. The swelling pressure of such mixture is an important factor in the design and long-term safety assessment of deep geological repositories. In this study, constant-volume swelling pressure tests were performed on the mixtures with different claystone fractions and dry densities. The test results show that the swelling pressure of the mixtures decreased with the increasing claystone fraction and decreasing dry density. According to the experimental results, the contribution of claystone to the global swelling pressure was further investigated. It was found that the deformation of claystone and its contribution to swelling pressure was highly dependent on the claystone fraction. As the claystone fraction was larger than 30%, the claystone in the mixture swelled, contributing to the global swelling pressure; On the contrary, as the claystone fraction was less than 30%, the swelling of claystone was inhibited by the bentonite and it worked an inert material without any contribution to the swelling pressure.

Long-Term Prediction of Radionuclide Release From Borehole Type Repositories

2003 ◽  
Author(s):  
L. B. Prozorov ◽  
S. A. Korneva
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Radiation Safety ◽  
Large Diameter ◽  
Development Program ◽  
Safety Standards ◽  
Engineered Barriers ◽  
Radionuclide Release ◽  
Long Term Prediction

As part of a development program for radioactive waste management, two test boreholes have been constructed at the MosNPO “Radon” Site to evaluate the conditions of LILW storage in such facilities, to observe the behaviour of engineered barriers as a function of time, the ability of the system to contain radionuclides and to test the reliability of a monitoring system. To obtain a licence for operation of such boreholes, MosNPO “Radon” specialists have prepared a package of documents, including a “Report on Safety Assessment of LILW Storage in Large Diameter Boreholes” [1]. On the basis of radiation safety standards and requirements being in force in Russian Federation, a range of possible accidents and emergencies during the operational period has been considered in this study. In this paper, the authors present results of a long term safety assessment of LILW disposal in the boreholes, performed within the framework of the above mentioned report.

The Assessment of the Long-Term Evolution of the Spent Nuclear Fuel Matrix by Kinetic, Thermodynamic and Spectroscopic Studies of Uranium Minerals.

1994 ◽  
Vol 353 ◽  
Author(s):  
Jordi Bruno ◽  
I. Casas ◽  
E Cera ◽  
R. C. Ewing ◽  
R. J. Finch ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Safety Assessment ◽  
Source Term ◽  
Spent Nuclear Fuel ◽  
Spectroscopic Studies ◽  
Spent Fuel ◽  
Term Evolution ◽  
Uranium Minerals ◽  
The Stability

AbstractThe long term behaviour of spent nuclear fuel is discussed in the light of recent thermodynamic and kinetic data on mineralogical analogues related to the key phases in the oxidative alteration of uraninite. The implications for the safety assessment of a repository of the established oxidative alteration sequence of the spent fuel matrix are illustrated with Pagoda calculations. The application to the kinetic and thermodynamic data to source term calculations indicates that the appearance and duration of the U(VI) oxyhydroxide transient is critical for the stability of the fuel matrix.

Sign in / Sign up

Export Citation Format

Share Document