New Perspectives for the Spent Nuclear Fuel Radionuclides Release Model in a Deep Geological Repository

2006 ◽  
Vol 985 ◽  
Author(s):  
Christophe Poinssot ◽  
Cécile FERRY ◽  
Arnaud POULESQUEN
Keyword(s):  
Nuclear Fuel ◽  
Source Term ◽  
Spent Nuclear Fuel ◽  
Deep Geological Repository ◽  
Term Evolution ◽  
Geological Repository ◽  
Definition Of ◽  
Release Model ◽  
The Impact

AbstractSpent Nuclear Fuel (SNF) source terms are used to define the release rate of radionuclides (RN) in a direct disposal and to assess the performance of this waste form. They classically distinguish between two contributions: (i) the Instant Release Fraction (IRF) of RN which are directly leached when water contacts the fuel, (ii) the slow and long term release of RN which are embedded within the fuel matrix. Recent experimental results bring significant input in our understanding and assessment of both contributions. However, they have not yet been integrated in the definition of the SNF source term. This paper will present the impact on the RN source term of the latest results on the SNF long term evolution and the key remaining scientific issues.

scholarly journals Seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel

Open Physics ◽  
2017 ◽  
Vol 15 (1) ◽  
pp. 486-493
Author(s):  
Zdeněk Kaláb ◽  
Jan Šílený ◽  
Markéta Lednická
Keyword(s):  
Czech Republic ◽  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Probabilistic Method ◽  
Seismic Stability ◽  
Historical Period ◽  
Deep Geological Repository ◽  
The Czech Republic ◽  
Geological Repository ◽  
The Impact

AbstractThis paper deals with the seismic stability of the survey areas of potential sites for the deep geological repository of the spent nuclear fuel in the Czech Republic. The basic source of data for historical earthquakes up to 1990 was the seismic website [10]. The most intense earthquake described occurred on September 15, 1590 in the Niederroesterreich region (Austria) in the historical period; its reported intensity is Io = 8-9. The source of the contemporary seismic data for the period since 1991 to the end of 2014 was the website [11]. It may be stated based on the databases and literature review that in the period from 1900, no earthquake exceeding magnitude 5.1 originated in the territory of the Czech Republic.In order to evaluate seismicity and to assess the impact of seismic effects at depths of hypothetical deep geological repository for the next time period, the neo-deterministic method was selected as an extension of the probabilistic method. Each one out of the seven survey areas were assessed by the neo-deterministic evaluation of the seismic wave-field excited by selected individual events and determining the maximum loading.Results of seismological databases studies and neo-deterministic analysis of Čihadlo locality are presented.

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.

Consequences of the Anticipated Long-Term Evolution of Spent Nuclear Fuel for the Assessment of the Release Rate of Radionuclides.

2002 ◽  
Vol 757 ◽  
Author(s):  
Christophe Poinssot ◽  
Patrick Lovera ◽  
Cécile Ferry ◽  
Jean-Marie Gras
Keyword(s):  
Nuclear Fuel ◽  
Source Term ◽  
Spent Nuclear Fuel ◽  
Long Term Evolution ◽  
Time Dependent ◽  
Geological Disposal ◽  
Long Term Storage ◽  
Term Evolution ◽  
Term Storage

ABSTRACTThe research conducted in the framework of the French research project on spent nuclear fuel (SNF) long - term evolution (PRECCI Project) has enlightened the potential significance of spent nuclear fuel intrinsic evolution in closed system for the assessment of radionuclide (RN) source term in long-term storage or geological disposal. Beyond others, alpha self-irradiation enhanced diffusion and evolution of the grain boundaries cohesion are two major processes which have to be accounted for in view of the RN source term models development. Accounting for these processes, operational models are developed, the aim of which is to quantitatively define the RN release rates from SNF in long-term storage or geological disposal. They distinguish basically an instantaneous contribution (IRF in geological disposal) and a time-dependent contribution (matrix oxidation or alteration). RN inventories associated to these two different processes have to be modeled since they are time-dependent due to the RN diffusion within the pellet. The present paper details the models that are developed in France in terms of assumptions, conservatism and robustness. It comes out from this work that for the instant release fraction, we have to consider a much higher instant release fraction than classically assumed (5–6% in geological disposal) in particular for geological disposal.

scholarly journals Assessment of the climate changes evolution for the long-term safety of the radioactive waste repository in the Czech Republic

2019 ◽  
Vol 133 ◽  
pp. 02005
Author(s):  
Markéta Camfrlová
Keyword(s):  
Czech Republic ◽  
Radioactive Waste ◽  
Spent Nuclear Fuel ◽  
Global Climate ◽  
Deep Geological Repository ◽  
Climatic Effects ◽  
The Czech Republic ◽  
Area Of Interest ◽  
Geological Repository

Nuclear energy accounts for a significant part of the total energy production in the Czech Republic, which is currently facing a problem dealing with the high-level radioactive waste (HLW) and the spent nuclear fuel (SNF). Deep repository is the safest option for storage of HLW. Rock environment of the area must guarantee the stability of the deep geological repository for at least 100,000 years. The aim of the research is a long-term evaluation of the climatic changes of the hypothetical area of interest, which corresponds to the candidate sites for deep geological repository in the Czech Republic. The occurrences of endogenous and exogenous phenomena, which could affect site stability, were evaluated. Concerning exogenous processes, research focuses mainly on the assessment of climatic effects. The climate scenarios for the Central Europe were examined – global climate change, glaciation, and the depth of permafrost as well as CO2 increase.

scholarly journals Assessment of the impact of selected changes in the deep geological repository model on its long-term safety

2020 ◽  
Vol 225 ◽  
pp. 06012
Author(s):  
Dorota Flamíková ◽  
Vladimír Nečas
Keyword(s):  
Effective Dose ◽  
Annual Effective Dose ◽  
Monitoring Program ◽  
Distribution Coefficients ◽  
Exposure Group ◽  
Deep Geological Repository ◽  
Adult Individual ◽  
Geological Repository ◽  
The Impact

The deep geological repository system provides long-term protection against the undesirable effects of ionizing radiation on the population and the environment. An important part of the long-term safety strategy is development of a monitoring program that collects information about the behaviour of the deep geological repository throughout its whole lifetime. A simplified model of the disposal system, geosphere, and biosphere was developed using the GoldSim simulation tool to demonstrate the behaviour of the hypothetical deep geological repository located in crystalline rocks. Also an initial model of the reference biosphere was created based on the scenario of an agricultural habitation (normal evolution scenario) and it was developed based on the recommendations provided in the BIOMASS methodology. After a significant period of time, disposal containers will be degraded and evolution changes in the repository system will occur. Several important parameters appear in the annual effective dose calculation for an individual from critical exposure group within the reference biosphere model. One of them are, for example, distribution coefficients and so-called translocation factors that define the transported rate of released radionuclides into the environment. This paper provides a view into the selected part of the deep geological repository through the data obtained by monitoring during the selected period of time. Simulations describing changes in the repository system. The aim of this contribution is to evaluate the impact of selected changes on the annual effective dose for an adult individual from a critical exposure group while it is assumed, that the respondent consumes contaminated crops and animal products. This model includes various biosphere components and multiple exposure pathways such as inhalation, ingestion and external exposure.

Mechanisms governing the release of radionuclides from spent nuclear fuel in geological repository: major outcomes of the European Project SFS

2006 ◽  
Vol 932 ◽  
Author(s):  
Christophe Poinssot ◽  
Cécile Ferry ◽  
Bernd Grambow ◽  
Manfred Kelm ◽  
Kastriot Spahiu ◽  
...  
Keyword(s):  
Nuclear Fuel ◽  
Spent Nuclear Fuel ◽  
Kinetic Scheme ◽  
Water Radiolysis ◽  
Large Set ◽  
Spent Fuel ◽  
Fuel Performance ◽  
Geological Repository ◽  
The Matrix ◽  
Release Model

ABSTRACTEuropean Commission supported a wide research project entitled “Spent Fuel Stability under repository conditions” (SFS) within the 5th FWP, the aim of which was to develop a common understanding of the radionuclides release from spent nuclear fuel in geological disposal and build a RN release model in order to assess the fuel performance. This project achieved by the end of 2004 focuses both on the Instant Release Fraction (IRF) model and the Matrix Alteration Model (MAM).A new IRF model was developed based on the anticipated performances of the various fuel microstructures (gap, rim, grains boundaries) and the potential diffusion of RN before the canister breaching. However, this model lets the choice to the end-user about the degree of conservativeness to consider.In addition, fuel alteration has been demonstrated to be linked to the production of radiolytic oxidants by water radiolysis at the fuel interface, the oxidation of the fuel interface by radiolytic oxidants and the subsequent release of uranium under the influence of aqueous ligands. A large set of experimental data was therefore acquired in order (i) to upgrade the current radiolytic kinetic scheme, (ii) to experimentally correlate the fuel alteration rate and the fuel specific alpha activity by performing experiments on alpha doped samples, (iii) to experimentally test the potential inhibitor effect of hydrogen on fuel dissolution. Based on these results, a new MAM was developed, which was also calibrated using the experiments on inactive UO2 samples. This model was finally applied to representative granitic, salt and clayey environment to predict spent fuel long-term fuel performance.

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.

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