Modelling of a Generic Near-Surface Disposal System

2012 ◽  
Vol 1475 ◽  
Author(s):  
Noelia R. Sileo ◽  
Néstor O. Fuentes
Keyword(s):  
Performance Assessment ◽  
Waste Disposal ◽  
Near Field ◽  
Simple Calculation ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Near Surface ◽  
License Application ◽  
Numerical Tools

ABSTRACTDevelopment of numerical tools for performance assessment studies of radioactive waste disposal facilities, must address the management of the wide-ranging uncertainties associated with the long-term behaviour of these complex systems. Different approaches and assumptions are made in order to identify and describe relationships between the disposal system and its environment. They take into account, among other factors, the uncertainties associated with temporal evolution of the system within a proposed scenario; the landscape changes arising from future human actions, climate and geological events and processes; the relationships between components of the disposal system and its immediate environment; the behaviour and characteristics of radionuclides within the system and their role in contributing to radiation exposure. In all cases, the different scenario-based models are typically used to determine the radiological significance of potential future discharges from waste disposal facilities. However, it is important to keep always in mind that in any specific case, the purpose of developing and/or applying a model may vary from a simple calculation (e.g. to support concept development) to detailed site-specific performance assessment in support of a disposal license application. The assumptions and modelling simplifications that are appropriate to one type of calculation may not be so easily justified in different circumstances. In order to develop the capability of modelling different long-term scenarios for a generic disposal site for low and intermediate level radioactive wastes, implementation of models of both the near-field/geosphere and biosphere were performed using general approaches for geosphere-biosphere interface, with sub-models for the whole system.

scholarly journals Source Term Development For Tritium at the Sheffield Disposal Site

1984 ◽  
Vol 44 ◽  
Author(s):  
D. R. Mackenzie ◽  
R. E. Barletta ◽  
J. F. Smalley ◽  
C. R. Kempf ◽  
R. E. Davis
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Source Term ◽  
Fuel Cycle ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Waste Disposal Site ◽  
Groundwater Samples ◽  
Low Level Radioactive Waste

AbstractThe Sheffield low-level radioactive waste disposal site, which ceased operation in 1978, has been the focus of modeling efforts by the NRC for the purpose of predicting long-term site behavior. To provide the NRC with information required for its modeling effort, a study to define the source term for tritium in eight trenches at the Sheffield site has been undertaken. Tritium is of special interest since significant concentrations of the isotope have been found in groundwater samples taken at the site and at locations outside the original site boundary. Previous estimates of tritium site inventory at Sheffield are in wide disagreement. In this study, the tritium inventory in the eight trenches was estimated by reviewing the radioactive shipping records (RSRs) for waste buried in these trenches. It has been found that the tritium shipped for burial at the site was probably higher than previously estimated. In the eight trenches surveyed, which amount to roughly one half the total volume and activity buried at Sheffield, approximately 2350 Ci of tritium from non-fuel cycle sources were identified.

CSAMT exploration at Sellafield: Characterization of a potential radioactive waste disposal site

Geophysics ◽  
2000 ◽  
Vol 65 (4) ◽  
pp. 1070-1079 ◽  
Author(s):  
Martyn J. Unsworth ◽  
Xinyou Lu ◽  
M. Don Watts
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Waste Disposal Site ◽  
Controlled Source ◽  
High Level ◽  
Cultural Noise ◽  
And Inversion

The long term disposal of radioactive waste in an underground repository requires the detailed geological evaluation of a potential site. Owing to their inherent sensitivity to the presence of fluids in rocks, electromagnetic (EM) methods have an important role in this assessment. Controlled‐source EM techniques are especially useful in strong anthropogenic noise environments such as industrial locations. However the complexity of modeling and inversion can limit the quantitative interpretation of controlled‐source EM data. A potential radioactive waste disposal site at Sellafield in Great Britain has been investigated using a variety of EM exploration techniques. Controlled‐source audio‐frequency magnetotelluric (CSAMT) data have given the best subsurface information in an environment that has a high level of cultural noise. One‐dimensional inversions of the Sellafield CSAMT data were found to be inadequate; 2.5-D forward modeling and inversion were used to interpret the data. The resulting resistivity models show good agreement with well log data collected at the site. These resistivity models show the presence of a large zone of hypersaline groundwater extending 1 km inland towards the potential repository and indicate the effect of faults on the hydrogeology.

A long term baseline and variability of natural radionuclides in groundwater at the Vaalputs low-level radioactive waste disposal facility, Namaqualand, South Africa: regional implications

2020 ◽  
Vol 123 (1) ◽  
pp. 105-116 ◽  
Author(s):  
H.C.F. Pretorius ◽  
M. Tredoux ◽  
M.A.G. Andreoli ◽  
P.D. Vermeulen
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Structural Damage ◽  
Near Field ◽  
Natural Radionuclides ◽  
Radioactive Waste Disposal ◽  
World Health ◽  
Disposal Site ◽  
Spent Fuel ◽  
Disposal Facility

Abstract Vaalputs is the only South African nuclear waste disposal facility; it is licensed to dispose of low and intermediate level radioactive waste. Possible disposal of long-lived waste, potentially including spent fuel rods, prompted a study to establish a baseline of naturally-occurring radionuclides from the U and Th decay chains in the groundwater of Vaalputs. This baseline was created by investigating a dataset containing 25 years of analyses of the groundwater at the Vaalputs site. The behaviour over time, of 23 radionuclides in groundwater samples from 13 annually and three quarterly sampled boreholes, was evaluated and integrated in order to establish changing trends in the activities of radionuclides, the relative contributions of individual radionuclides to total radiation levels and how these were influenced by groundwater conditions. 238U levels showed a natural anomaly in the near-field of the disposal site that was attributed to the underlying basement rocks (granites) which are anomalously enriched in U. A set of duplicate samples from 2009 determined that the activity ratio of 234U/238U in the groundwater of Vaalputs is 4.1; this is ascribed to more rapid leaching of 234U relative to 238U, because of increased crystal structural damage around sites surrounding 234U atoms. High levels of 226Ra, unsupported by 238U, were found in groundwater from boreholes on the western side of the property: this groundwater yielded low values for 234U/238U, lower pH and stronger oxidizing conditions than groundwater from the rest of the area. The absence of overlying sedimentary rocks, which tend to ameliorate the effects of high radiation from granites by absorption, is suggested as the reason for the different geochemical conditions of the groundwater from boreholes in the west. This suggestion may apply to those boreholes elsewhere in Namaqualand with low published concentrations of 238U, but exceptionally high levels of α -and β-emitters. 232Th and its daughter radionuclides yielded radiation levels far below the guideline of 1 Bq.L-1 specified by the World Health Organization; this result is in line with the known low mobility of Th in groundwater systems.

Fe(III) Reduction in the Subsurface at a Low-level Radioactive Waste Disposal Site

2010 ◽  
Vol 27 (3) ◽  
pp. 231-239 ◽  
Author(s):  
Michael J. Wilkins ◽  
Francis R. Livens ◽  
David J. Vaughan ◽  
Jonathan R. Lloyd ◽  
Ian Beadle ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Waste Disposal Site ◽  
Low Level ◽  
Low Level Radioactive Waste

Geological and contaminant transport assessment of a low level radioactive waste disposal site

2019 ◽  
Vol 197 ◽  
pp. 174-183 ◽  
Author(s):  
Abdel-Aal M. Abdel-Karim ◽  
Ahmed A. Zaki ◽  
Waheed Elwan ◽  
Mohamed R. El-Naggar ◽  
Mahmoud M. Gouda
Keyword(s):  
Radioactive Waste ◽  
Contaminant Transport ◽  
Waste Disposal ◽  
Radioactive Waste Disposal ◽  
Disposal Site ◽  
Waste Disposal Site ◽  
Low Level ◽  
Low Level Radioactive Waste

scholarly journals Peculiarities of 137Cs Sorption/Desorption by Bentonite Clays of Cherkasy Deposit from Groundwater Model Solutions of Radioactive Waste Disposal Facilities at the “Vector” Production Complex

2021 ◽  
Vol 21 (2) ◽  
pp. 78-87
Author(s):  
B. H. Shabalin ◽  
◽  
К. К. Yaroshenko ◽  
S. P. Buhera
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Water Soluble ◽  
Radioactive Waste Disposal ◽  
Groundwater Model ◽  
Static Mode ◽  
Near Surface ◽  
Model Solutions ◽  
Production Complex ◽  
Bentonite Clays

The main feature of bentonite clays is their high sorption capacity with respect to various radionuclides. The study of sorption kinetics of 137Cs was performed in the static mode by natural and industrial soda modified (PBA-20) samples of bentonite clays of Cherkasy deposit of bentonite and paligorskite clays from groundwater model solutions of radioactive waste disposal facilities of “Vector” production complex under various pH and solution mineralisation. The desorption of occluded samples was studied in distilled water and acetateammonium buffer solution. The value of the degree of sorption (S) for 137Cs on the modified samples exceeds 90%, for natural bentonite this indicator is lower (about 83–85%). On both types of bentonite with increasing time of their contact with aqueous solution and pH, there is a redistribution of water-soluble, ion-exchange and fixed forms of radionuclide and the share of the latter, that is not participating in migration processes increases, indicating the ability of bentonites to immobilize effectively for a long time. It is shown that Na-modified bentonite has higher proportion of sorption in fixed form compared to natural one and its application increases the probability of irreversible fixation of migrating radionuclides under non-optimal conditions of sorption (high pH (>11) of water after prolonged contact with cement-concrete components of engineering barriers) and thus increases the environmental safety of the storage facility. It is shown that bentonite clays of the Cherkasy deposit can serve as an effective material for creating anti-migration barriers of I and II stages of surface/near-surface storage facilities for radioactive waste disposal at the “Vector” production complex. At the same time, the issue of practical application of bentonite clays of Cherkasy deposit for accurate predictions of securing radioactive waste disposal of Chornobyl origin requires further study of sorption-desorption properties of bentonite clay with respect to other fission products and actinides

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