Development of the Code Melodie for Long Term Risk Assessment of Nuclear Waste Repositories

1985 ◽  
Vol 50 ◽  
Author(s):  
P. Goblet ◽  
P. Guetat ◽  
J. Lewi ◽  
J-P Mangin ◽  
G. De Marsily ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Nuclear Waste ◽  
Computer Code ◽  
Source Model ◽  
High Level Waste ◽  
Chemical Components ◽  
Advection Dispersion ◽  
The Individual ◽  
High Level ◽  
Waste Repositories

AbstractMELODIE is a computer code developed at the CEA/IPSN for risk assessment of nuclear waste repositories in geological formations. The interactive evolution of the source, geosphere and biosphere is studied for periods of time longer than 100 000 years. In its first version, the code can describe a repository in granite rock located at a specific site.The code is built in a modular form which allows to use different versions of the sub-system models.The basic model for radionuclide migration and hydrpgeology is a subroutine version of the METIS code developed by ENSMP. METIS is a 2D finite element code which solves the advection-dispersion equation for porous media with explicit fracture representation. Linear adsorption kinetics is included as well as matrix diffusion and radionuclide decay chains.The source model developed at CEA/DRDD**** is derived from CONDIMENT which is a 1D finite difference code describing the behaviour of high level waste packages. Four axisymetric layers are individualized: glass matrix, container, bentonite and granite. The glass leaching is modelled as a dissolution and diffusion process of the individual chemical components.The biosphere model ABRICOT developed at the CEA/DPT** is based on a detailed description of agricultural activities defined in individual systems.MELODIE is tested by participation to international exercices such as Pagis [1], Intracoin [2] and Hydrocoin [3]. Future developments will include introduction of scenarios constructed from geoprospective studies and algorithms for sensitivity studies.

Condiment: Source Code for Risk Assessment of French Nuclear Waste Repository

1988 ◽  
Vol 127 ◽  
Author(s):  
J. P. Mangin ◽  
E. Mouche ◽  
P. Lovera ◽  
H. Nguyen Ngoc
Keyword(s):  
Risk Assessment ◽  
Nuclear Waste ◽  
Source Code ◽  
Computer Code ◽  
Nuclear Waste Repository ◽  
Single Element ◽  
Aqueous Corrosion ◽  
High Level ◽  
Diffusion Convection ◽  
Waste Repositories

ABSTRACTCONDIMENT is the source code used in MELODIE, the overall French computer code for risk assessment of nuclear waste repositories in geological formations. This code models the diffusion-convection of elements released by a waste package, up to a distance of a few meters from the package. Two versions have been developed simultaneously:- CONDIMENT2 deals with the case of a single element. This version is more specifically designed for vitrified high-level wastes. The boundary conditions are furnished by studies on aqueous corrosion of French nuclear glass R7T7.- CONDIMENT3, deals with two ions that are liable to precipitate. This version is more specifically designed for wastes immobilized in cement.CONDIMENT3 is verified in a configuration for which an analytical solution exists.

Predicting Pu Concentrations in Solutions Contacting Geologic Materials

1981 ◽  
Vol 6 ◽  
Author(s):  
Richard G. Strickert ◽  
Dhanpat Rai
Keyword(s):  
Nuclear Waste ◽  
Safety Assessment ◽  
High Level Waste ◽  
Stable Phase ◽  
Borosilicate Glasses ◽  
Geologic Materials ◽  
Solid Phases ◽  
High Level ◽  
Waste Repositories

ABSTRACTKnowledge of Pu solid phases present in nuclear wastes is important for predicting the geochemical behavior of Pu. Thermodynamic data and experimental measurements using discrete Pu compounds, Pu-doped borosilicate glasses (simulating a high-level waste form), and Pu contaminated sediments suggest that PuO2(c) is very stable and is expected to be present in the repository. The solubility of the stable phase, such as PuO2(c), can be used to predict the maximum Pu concentration in solutions for long-term safety assessment of nuclear waste repositories.

Environmental Remediation of High-Level Nuclear Waste in Geological Repository: Modified Computer Code Creates Ultimate Benchmark in Natural Systems

2010 ◽  
Author(s):  
Geoffrey J. Peter
Keyword(s):  
Nuclear Waste ◽  
Environmental Remediation ◽  
Computer Code ◽  
Nuclear Waste Repository ◽  
Natural Systems ◽  
Permanent Storage ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Waste Repositories

Isolation of high-level nuclear waste in permanent geological repositories has been a major concern for over 30 years due to the migration of dissolved radio nuclides reaching the water table (10,000-year compliance period) as water moves through the repository and the surrounding area. Repositories based on mathematical models allow for long-term geological phenomena and involve many approximations; however, experimental verification of long-term processes is impossible. Countries must determine if geological disposal is adequate for permanent storage. Many countries have extensively studied different aspects of safely confining the highly radioactive waste in an underground repository based on the unique geological composition at their selected repository location. This paper discusses two computer codes developed by various countries to study the coupled thermal, mechanical, and chemical process in these environments, and the migration of radionuclide. Further, this paper presents the results of a case study of the Magma-hydrothermal (MH) computer code, modified by the author, applied to nuclear waste repository analysis. The MH code verified by simulating natural systems thus, creating the ultimate benchmark. This approach based on processes similar to those expected near waste repositories currently occurring in natural systems.

scholarly journals Spent Fuel as a Waste Form - Data Needs to Allow Long Term Performance Assessment Under Repository Disposal Conditions.

1986 ◽  
Vol 84 ◽  
Author(s):  
V. M. Oversby
Keyword(s):  
Performance Assessment ◽  
Waste Form ◽  
High Level Waste ◽  
Detailed Knowledge ◽  
Spent Fuel ◽  
Expected Performance ◽  
High Level ◽  
Term Performance ◽  
Physical And Chemical ◽  
Waste Repositories

AbstractPerformance assessment calculations are required for high level waste repositories for a period of 10,000 years under NRC and EPA regulations. In addition, the Siting Guidelines (IOCFR960) require a comparison of sites following site characterization and prior to final site selection to be made over a 100,000 year period. In order to perform the required calculations, a detailed knowledge of the physical and chemical processes that affect waste form performance will be needed for each site. While bounding calculations might be sufficient to show compliance with the requirements of IOCFR60 and 40CFRI91, the site comparison for 100,000 years will need to be based on expected performance under site specific conditions. The only case where detailed knowledge of waste form characteristics in the repository would not be needed would be where radionuclide travel times to the accessible environment can be shown to exceed 100,000 years. This paper will review the factors that affect the release of radionuclides from spemt fuel under repository conditions, summarize our present state of knowledge, and suggest areas where more work is needed in order to support the performance assessment calculations.

Assessment of Redox Conditions in the Near Field of Nuclear Waste Repositories: Application to the Swiss high-level and intermediate level waste disposal concept

2003 ◽  
Vol 807 ◽  
Author(s):  
Paul Wersin ◽  
Lawrence H. Johnson ◽  
Bernhard Schwyn
Keyword(s):  
Solid Phase ◽  
Near Field ◽  
Intermediate Level ◽  
Redox Conditions ◽  
High Level Waste ◽  
Redox Potentials ◽  
Spent Fuel ◽  
Reducing Conditions ◽  
High Level ◽  
Waste Repositories

ABSTRACTRedox conditions were assessed for a spent fuel and high-level waste (SF/HLW) and an intermediate-level waste (ILW) repository. For both cases our analysis indicates permanently reducing conditions after a relatively short oxic period. The canister-bentonite near field in the HLW case displays a high redox buffering capacity because of expected high activity of dissolved and surface-bound Fe(II). This is contrary to the cementitious near field in the ILW case where concentrations of dissolved reduced species are low and redox reactions occur primarily via solid phase transformation processes.For the bentonite-canister near field, redox potentials of about -100 to -300 mV (SHE) are estimated, which is supported by recent kinetic data on U, Tc and Se interaction with reduced iron systems. For the cementitious near field, redox potentials of about -200 to -800 mV are estimated, which reflects the large uncertainties related to this alkaline environment.

Optimal mixing scheme for graphite–bentonite mixtures used as buffer materials in high-level waste repositories

2021 ◽  
Vol 80 (17) ◽  
Author(s):  
Yun-zhi Tan ◽  
Zi-yang Xie ◽  
Fan Peng ◽  
Fang-hong Qian ◽  
Hua-jun Ming
Keyword(s):  
High Level Waste ◽  
High Level ◽  
Waste Repositories ◽  
Optimal Mixing
Sign in / Sign up

Export Citation Format

Share Document