This report summarize the results of the IAEA's Cooperative Research Project, which began in ... more This report summarize the results of the IAEA's Cooperative Research Project, which began in 2005 and was completed in 2010. The CRP has the overall purpose to transfer modelling expertise and numerical simulation technology to countries needing them for their national nuclear waste management programmes. Basic activities as part of this CRP consisted of (1) demonstrating the use of modelling strategies to address relevant issues using site-specific data (if available), (2), gain insights in the reliability and uncertainty of numerical model predictions, and (3) improving the modelling capabilities at institutions in the participating Member States. Author's contributions comprise source term calculations using GRAPOS1 (a module of the EMOS code) and DUST-MS codes, contaminant transport calculations with PORFLOW, leading the comparison study on the impact on the impact of the disposal concept (Section 4.2.1), contributing to the comparison study on the impact of the conceptu...
The aim of this paper is to give essential information on the current status of the studies devel... more The aim of this paper is to give essential information on the current status of the studies developed in the framework of the Research Contract no. T02.10.24 “The development of numerical models and computer codes in support of siting and performance assessment studies of geologic repository in crystalline and ingenuous rocks”. The work performed included groundwater flow and radionuclide transport simulations for the ‘semi-generic’ Veresnia site (Ukraine), development of a near-field release model for spent nuclear fuel from CANDU reactors and performing a THM analysis for a single canister. For the far-field model, the conceptual model provided by Ukraine was simulated with the FEFLOW 5.2 code, using a porous medium model with embedded horizontal and vertical discrete fractures. The disposal concept for CANDU fuel in granite was adapted following a Canadian concept, and the source term calculation was conducted with the the near-field transport code GRAPOS, part of the EMOS packag...
Romania requires a deep geological disposal research for the spent fuel (SF) produced by its nucl... more Romania requires a deep geological disposal research for the spent fuel (SF) produced by its nuclear power system based on CANDU reactors. Up to date there is not a final decision concerning the host rock. So, different type rocks are taken into account. Based on two NATO-contracts with the GRS-Braunschweig, namely 1) NATO-LG (ES) 972 750/1988 and 2) NATO-CLG(EST) 976 810/2001, a hypothetical repository has been considered both in granite and salt formations. The key parameter for assessing long-term safety is the radiation exposure to the biosphere. The results of the calculations demonstrate that CANDU SF may be safely disposed.
A long-term safety analysis for direct disposal in granite formation of spent nuclear fuel from p... more A long-term safety analysis for direct disposal in granite formation of spent nuclear fuel from power plants of CANDU type has been performed. The results are compared with previous results for disposal of spent LWR fuel. Additional parameter variations have been performed for both fuel types.
A long-term safety assessment of a repository for either spent CANDU or LWR fuel elements in a sa... more A long-term safety assessment of a repository for either spent CANDU or LWR fuel elements in a salt formation has been performed. A hypothetical repository site has been considered, using data of the European Community project PAGIS for all parts of the system: near field, overburden, and biosphere. Three scenarios have been taken into account: subrosion as the normal evolution of the salt dome, a combined scenario with brine intrusion from the overburden and from undetected brine pockets, and a cavern scenario representing future human actions. Spent fuel elements have been assumed to be disposed of in big storage casks in drifts. For reasons of comparability, the same source term model has been applied for both waste types, but different inventories of radionuclides and different heat production rates have been taken into account. The key parameter for assessing long-term safety was the radiation exposure in the biosphere. The results of the calculations demonstrate that both type...
Performance assessment of salt isolation system for CANDU and LWR spent nuclear fuel
A long-term safety assessment of a repository for either spent CANDU or LWR fuel elements in a sa... more A long-term safety assessment of a repository for either spent CANDU or LWR fuel elements in a salt formation has been performed. A hypothetical repository site has been considered, using data of the European Community project PAGIS for all parts of the system: near field, overburden, and biosphere. Three scenarios have been taken into account: subrosion as the normal evolution of the salt dome, a combined scenario with brine intrusion from the overburden and from undetected brine pockets, and a cavern scenario representing future human actions. Spent fuel elements have been assumed to be disposed of in big storage casks in drifts. For reason of comparability, the same source term model has been applied for both waste types, but different inventories of radionuclides and different heat productions have been taken into account. The key parameter for assessing long-term safety was the radiation exposure in the biosphere. The results of the calculations demonstrate that both types of w...
The paper presents the derivation of the flow and transport parameters for Tritium and C-14, from... more The paper presents the derivation of the flow and transport parameters for Tritium and C-14, from the breakthrough curves of flow-through experiments in two limestone columns of different particle sizes. The limestone rock, bored from Dobrogea region, was investigated at Los Alamos National Laboratories (LANL), as part of collaboration agreement with the Institute for Nuclear Research Pitesti. Flow parameters obtained from the inverse modelling of H-3 transport with HDRUS-1D code were further used to estimate transport parameters for C-14. Transport of C-14 is modelled by physical non-equilibrium with equilibrium non-linear sorption in the immobile region, kinetic sorption in the mobile liquid region and irreversible sorption, and attachment-detachment model with irreversible sorption. For a better understanding of the sorption mechanisms, additional information is needed, concerning rock mineralogical composition, water chemistry, determination of resident concentrations and a better documentation of the experimental works.
This report summarize the results of the IAEA's Cooperative Research Project, which began in 2005... more This report summarize the results of the IAEA's Cooperative Research Project, which began in 2005 and was completed in 2010. The CRP has the overall purpose to transfer modelling expertise and numerical simulation technology to countries needing them for their national nuclear waste management programmes. Basic activities as part of this CRP consisted of (1) demonstrating the use of modelling strategies to address relevant issues using site-specific data (if available), (2), gain insights in the reliability and uncertainty of numerical model predictions, and (3) improving the modelling capabilities at institutions in the participating Member States.
The project PAMINA (Performance Assessment methodologies in application to guide the development ... more The project PAMINA (Performance Assessment methodologies in application to guide the development of the safety case) was conducted from 2007 to 2009 on the European level to improve and harmonise integrated performance assessment methodologies and tools for various disposal concepts of long-lived radioactive waste and spent nuclear fuel in different deep geological environments. The following report presents the contributions of the GRS Braunschweig to the PAMINA project comprising the following topics:
Dissemination Level PU Public X RE Restricted to a group specified by the partners of the [PAMINA... more Dissemination Level PU Public X RE Restricted to a group specified by the partners of the [PAMINA] project CO Confidential, only for partners of the [PAMINA] project PAMINA Sixth Framework programme, 08.12.2009 2 PAMINA Sixth Framework programme, 08.12.2009 3 This report was compiled from contributions by the following authors: (in alphabetical order) Dieter Buhmann (GRS) Jacques Grupa (NRG) Jaap Hart (NRG) Rolf-Peter Hirsekorn (GRS) Alice Ionescu (GRS) Christian Lerch (DBE-TEC) André Rübel (GRS) Anke Schneider (GRS) Thomas J. Schröder (NRG) DBE-TEC: Deutsche Gesellschaft zum Bau und Betrieb von Endlagern für Abfallstoffe (DBE) -PAMINA Sixth Framework programme, 08.12.2009 4 PAMINA Sixth Framework programme, 08.12.2009 5 Foreword The work presented in this report was developed within the Integrated Project PAMINA: Performance Assessment Methodologies IN Application to Guide the Development of the Safety Case. This project is part of the Sixth Framework Programme of the European Commission.
In Belgium, the Boom Clay formation is considered to be the reference formation for HLW disposal ... more In Belgium, the Boom Clay formation is considered to be the reference formation for HLW disposal R&D. Assessments to date have shown that the host clay layer is a very efficient barrier for the containment of the disposed radionuclides. Due to absence of significant water movement), diffusion -the dominant transport mechanism, combined with generally high retardation of radionuclides, leads to extremely slow radionuclide migration. However, trivalent lanthanides and actinides form easily complexes with the fulvic and humic acids which occur in Boom Clay and in its interstitial water. Colloidal transport may possibly result in enhanced radionuclide mobility, therefore the mechanisms of colloidal transport must be better understood. Numerical modeling of colloidal facilitated radionuclide transport is regarded an important means for evaluating its importance for long-term safety.
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Papers by Alice Ionescu