Simulation of Radionuclide Release and Subsurface Transport for LILW New Romanian Repository

2001 ◽  
Author(s):  
Liana Didita ◽  
Petre Ilie ◽  
Margarit Pavelescu ◽  
Alexandru Danchiv ◽  
George Martac
Keyword(s):  
Safety Assessment ◽  
Source Term ◽  
Control Period ◽  
Radionuclide Transport ◽  
Assessment Methodology ◽  
Saturated Zone ◽  
Near Surface ◽  
Institutional Control ◽  
Radionuclide Release ◽  
Natural Barrier

Abstract This paper presents the main stages covered in development of the safety assessment methodology for near surface Romanian repository. It also describes the modeling approaches and assumptions used in source term modeling as well as the radionuclides transport through the unsaturated and saturated zones. In the paper, the repository performance is assessed only by the normal evolution scenario and the beginning of the institutional control period. Transport modeling through unsaturated zone emphasizes its behaviour as a natural barrier in radionuclide migration’s way. Only a brief discussion of radionuclide transport through the saturated zone is given in this paper. The discussion is related first to the model’s characteristics, followed by the presentation of the results.

An Integrated Safety Assessment System for Near-Surface Disposal of Low- and Intermediate-Level Radioactive Waste in Korea

2003 ◽  
Author(s):  
JooWan Park ◽  
Chang-Lak Kim ◽  
Jin Beak Park ◽  
Eun Yong Lee ◽  
Youn Myoung Lee ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Assessment System ◽  
Intermediate Level ◽  
Radioactive Waste Disposal ◽  
System Level ◽  
Assessment Methodology ◽  
Regulatory Requirements ◽  
Near Surface ◽  
Intermediate Level Radioactive Waste

An integrated safety assessment system to be used for evaluation of near-surface disposal concept has been developed within the framework of safety assessment methodology taken for low- and intermediate-level radioactive waste disposal in Korea. It is to provide an evaluation of the safety of the disposal system in a clear, comprehensive and well-documented manner, and to integrate the results into a defensible package showing reasonable assurance of compliance with regulatory requirements for licensing application. This system is made up of two key components, a system-level safety assessment code and an input database/quality assurance module for safety assessment, which both are interfaced with each other.

scholarly journals Scenarios and Pathways of Radionuclide Releases from Near-Surface Waste Disposal Facilities: A Brief Overview of Historical Evidence

2020 ◽  
pp. 21-27
Author(s):  
D. Bugai ◽  
R. Avila
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Safety Assessment ◽  
Historical Evidence ◽  
Nuclear Facilities ◽  
Near Surface ◽  
Soil Covers ◽  
Low Level ◽  
Radionuclide Release ◽  
Early Degradation

The very low-level waste (VLLW) produced during decommissioning of nuclear facilities can be suitable for disposal in landfill type facilities. Considering the similarities in design, the experience gained in near-surface disposal of radioactive waste in trenches and vaults is relevant to the issue of VLLW disposal in landfills. This paper presents a brief review of internationally reported cases of radionuclide releases from near-surface disposal facilities. Based on this review, the conclusions are made that the following radionuclide release and exposure scenarios should be accounted for in safety assessment of VLLW disposal in landfills: i) leaching from waste to groundwater by atmospheric precipitations; ii) bath-tubing scenario; iii) scenarios caused by extreme meteorological and hydrological events (erosion, flooding, etc.); iv) human intrusion. The gaseous transport deserves attention for a number of relevant radionuclides, such as (C-14, Rn-222, etc.). In addition, the possibility of early degradation of engineered containment structures (soil covers, bottom seals) should be cautiously considered.

Influence of Cracks in Cementitious Engineered Barriers in a Near-Surface Disposal System: Assessment Analysis of the Belgian Case

2013 ◽  
Author(s):  
Janez Perko ◽  
Suresh C. Seetharam ◽  
Diederik Jacques ◽  
Dirk Mallants ◽  
Wim Cool ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Safety Assessment ◽  
Total System ◽  
Near Surface ◽  
Disposal Facility ◽  
The Matrix ◽  
Flow Through ◽  
System Assessment ◽  
Engineered Barriers ◽  
Radionuclide Release

In large cement-based structures such as a near surface disposal facility for radioactive waste voids and cracks are inevitable. However, the pattern and nature of cracks are very difficult to predict reliably. Cracks facilitate preferential water flow through the facility because their saturated hydraulic conductivity is generally higher than the conductivity of the cementitious matrix. Moreover, sorption within the crack is expected to be lower than in the matrix and hence cracks in engineered barriers can act as a bypass for radionuclides. Consequently, understanding the effects of crack characteristics on contaminant fluxes from the facility is of utmost importance in a safety assessment. In this paper we numerically studied radionuclide leaching from a crack-containing cementitious containment system. First, the effect of cracks on radionuclide fluxes is assessed for a single repository component which contains a radionuclide source (i.e. conditioned radwaste). These analyses reveal the influence of cracks on radionuclide release from the source. The second set of calculations deals with the safety assessment results for the planned near-surface disposal facility for low-level radioactive waste in Dessel (Belgium); our focus is on the analysis of total system behaviour in regards to release of radionuclide fluxes from the facility. Simulation results are interpreted through a complementary safety indicator (radiotoxicity flux). We discuss the possible consequences from different scenarios of cracks and voids.

scholarly journals Silicified serpentinite – a residuum of a Tertiary palaeo-weathering surface in the United Arab Emirates

2012 ◽  
Vol 150 (3) ◽  
pp. 385-395 ◽  
Author(s):  
ALICJA M. LACINSKA ◽  
MICHAEL T. STYLES
Keyword(s):  
United Arab Emirates ◽  
Middle Eocene ◽  
Temperate Climate ◽  
Mixing Zone ◽  
Saturated Zone ◽  
Near Surface ◽  
Silica Precipitation ◽  
Surface Mixing ◽  
Ph Conditions ◽  
Mineralizing Fluids

AbstractMineralogical studies of a silicified serpentinite from the United Arab Emirates throw light on the formative processes. The silicified serpentinite is a residuum of a palaeo-weathering surface that probably developed in a temperate climate with alternating wet and dry periods during middle Eocene to late Miocene times. The rock textures indicate that silicification occurred in a fluid-saturated zone. Silica precipitation is favoured at near-neutral pH. In this study we infer that these pH conditions of the mineralizing fluids could arise in a near-surface mixing zone where acidic meteoric and hyperalkaline groundwater fluids are mingled. This mingling is believed to have resulted from alternating processes of evaporation and precipitation that prevailed during dry and wet seasons, respectively. The silicified serpentinite is composed of > 95% quartz and exhibits a ghost texture of the protolith serpentinite. Preservation of the textures indicates an iso-volumetric grain-by-grain replacement by dissolution of Mg-silicate and simultaneous precipitation of either opal or microquartz as siliceous seeds. These were subsequently overgrown by silica that was probably remobilized from deeply weathered regolith elsewhere.

Safety studies on Korean fusion DEMO plant using Integrated Safety Assessment Methodology: Part 2

2015 ◽  
Vol 98-99 ◽  
pp. 2152-2156 ◽  
Author(s):  
Kyemin Oh ◽  
Myoung-suk Kang ◽  
Gyunyoung Heo ◽  
Hyoung-chan Kim
Keyword(s):  
Safety Assessment ◽  
Assessment Methodology ◽  
Safety Studies
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