The Modeler's Influence on Calculated Solubilities for Performance Assessments at the Äspö Hard-Rock Laboratory

1999 ◽  
Vol 556 ◽  
Author(s):  
A. T. Emrén ◽  
Randy Arthur ◽  
Pierre D. Glynn ◽  
Jude McMurry
Keyword(s):  
Data Base ◽  
Thermodynamic Data ◽  
Hard Rock ◽  
Solid Phase ◽  
Performance Assessments ◽  
Test Cases ◽  
Data Bases ◽  
Standard Data ◽  
System A ◽  
Rock Laboratory

AbstractFour researchers were asked to provide independent modeled estimates of the solubility of a radionuclide solid phase, specifically Pu(OH)4, under five specified sets of conditions. The objectives of the study were to assess the variability in the results obtained and to determine the primary causes for this variability.In the exercise, modelers were supplied with the composition, pH and redox properties of the water and with a description of the mineralogy of the surrounding fracture system A standard thermodynamic data base was provided to all modelers. Each modeler was encouraged to use other data bases in addition to the standard data base and to try different approaches to solving the problem.In all, about fifty approaches were used, some of which included a large number of solubility calculations. For each of the five test cases, the calculated solubilities from different approaches covered several orders of magnitude. The variability resulting firom the use of different thermodynamic data bases was in most cases, far smaller than that resulting from the use of different approaches to solving the problem.

scholarly journals Nagra/PSI Chemical Thermodynamic Data Base 01/01

2002 ◽  
Vol 90 (9-11) ◽  
Author(s):  
W. Hummel ◽  
U. Berner ◽  
E. Curti ◽  
F. J. Pearson ◽  
T. Thoenen
Keyword(s):  
Radioactive Waste ◽  
Data Base ◽  
Thermodynamic Data ◽  
Critical Appraisal ◽  
Fission Products ◽  
Performance Assessments ◽  
The Other ◽  
Chemical Thermodynamic ◽  
Carbonate Complexes

SummaryThe Nagra/PSI Chemical Thermodynamic Data Base has been updated to support performance assessments of the planned Swiss repositories for radioactive waste. The update from version 05/92 to 01/01 involved major revisions for most of the actinides and fission products. Altogether, more than 70% of the database contents have been revised. Data for U, Np, Pu, Am and Tc recommended by the NEA TDB project were considered in the update. Thermodynamic data for Th, Sn, Eu, Pd, Al, and solubility and metal complexation of sulphides and silicates were extensively reviewed. Data for Zr, Ni and Se were examined less rigorously as these elements are currently being reviewed in phase II of the NEA TDB project. Our experiences from this two year team effort can be summarised as follows. Detailed in-house reviews and critical appraisal of NEA recommendations greatly improved the chemical consistency and quality of the selected data. On the other hand, we could discern major gaps in the data, especially missing carbonate complexes. In some systems,

The use of thesauri in online retrieval

1984 ◽  
Vol 8 (2) ◽  
pp. 63-66 ◽  
Author(s):  
C.P.R. Dubois
Keyword(s):  
Information Retrieval ◽  
Data Base ◽  
Case Studies ◽  
Controlled Vocabulary ◽  
Free Text ◽  
Data Bases ◽  
Online Data ◽  
Controlled Vocabularies ◽  
Semantic Maps ◽  
Actual Use

The controlled vocabulary versus the free text approach to information retrieval is reviewed from the mid 1960s to the early 1980s. The dominance of the free text approach following the Cranfield tests is increasingly coming into question as a result of tests on existing online data bases and case studies. This is supported by two case studies on the Coffeeline data base. The differences and values of the two approaches are explored considering thesauri as semantic maps. It is suggested that the most appropriate evaluatory technique for indexing languages is to study the actual use made of various techniques in a wide variety of search environments. Such research is becoming more urgent. Economic and other reasons for the scarcity of online thesauri are reviewed and suggestions are made for methods to secure revenue from thesaurus display facilities. Finally, the promising outlook for renewed develop ment of controlled vocabularies with more effective online display techniques is mentioned, although such development must be based on firm research of user behaviour and needs.

scholarly journals Viruses in granitic groundwater from 69 to 450 m depth of the Äspö hard rock laboratory, Sweden

2008 ◽  
Vol 2 (5) ◽  
pp. 571-574 ◽  
Author(s):  
Jennifer E Kyle ◽  
Hallgerd S C Eydal ◽  
F Grant Ferris ◽  
Karsten Pedersen
Keyword(s):  
Hard Rock ◽  
Rock Laboratory ◽  
Granitic Groundwater

Modelling the Prototype Repository

2018 ◽  
Vol 482 (1) ◽  
pp. 241-260 ◽  
Author(s):  
V. Tsitsopoulos ◽  
S. Baxter ◽  
D. Holton ◽  
J. Dodd ◽  
S. Williams ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Host Rock ◽  
Hard Rock ◽  
Task Force ◽  
Fractured Rock ◽  
Fracture Network ◽  
Atmospheric Conditions ◽  
Predictive Capability ◽  
Rock Laboratory ◽  
Modelling Methodology

AbstractThe Prototype Repository (PR) tunnel is located at the Äspö Hard Rock Laboratory near Oskarshamn in the southeast of Sweden. In the PR tunnel, six full-sized deposition holes (8.37 m deep and 1.75 m in diameter) have been constructed. Each deposition hole is designed to mimic the Swedish reference system for the disposal of nuclear fuel, KBS-3V. The PR experiment is designed to provide a full-scale simulation of the emplacement of heat-generating waste. There are three phases to the experiment: (1) the open tunnel phase following construction, where both the tunnel and deposition holes are open to atmospheric conditions; (2) the emplacement of canisters (containing heaters), backfill and seal in the first section of the tunnel; and (3) the emplacement of canisters, backfill and seal in the second section of the tunnel. This work describes the numerical modelling, performed as part of the engineered barrier systems (EBS) Task Force, to understand the thermo-hydraulic (TH) evolution of the PR experiment and to provide a better understanding of the interaction between the fractured rock and bentonite surrounding the canister at the scale of a single deposition tunnel. A coupled integrated TH model for predicting the wetting and the temperature of bentonite emplaced in fractured rock was developed, accounting for the heterogeneity of the fractured rock. In this model, geometrical uncertainties of fracture locations are modelled by using several stochastic realizations of the fracture network. The modelling methodology utilized information available at early stages of site characterization and included site statistics for fracture occurrence and properties, as well as proposed installation properties of the bentonite. The adopted approach provides an evaluation of the predictive capability of models, it gives an insight of the uncertainties to data and demonstrates that a simplified equivalent homogeneous description of the fractured host rock is insufficient to represent the bentonite resaturation.

scholarly journals Electric resistivity and seismic refraction tomography, a challenging joint underwater survey at Äspö Hard Rock Laboratory

2016 ◽  
Author(s):  
Mathias Ronczka ◽  
Kristofer Hellman ◽  
Thomas Günther ◽  
Roger Wisen ◽  
Torleif Dahlin
Keyword(s):  
Nuclear Power ◽  
Hard Rock ◽  
Seismic Refraction ◽  
Three Dimensional ◽  
Test Site ◽  
Fracture Zones ◽  
Rock Laboratory ◽  
Refraction Tomography ◽  
Local Point ◽  
General Test

Abstract. Tunnelling below water passages is a challenging task in terms of planning, pre-investigation and construction. Fracture zones in the underlying bedrock lead to low rock quality and thus reduced stability. For natural reasons they tend to be more frequent at water passages. Ground investigations that provide information of the subsurface are necessary prior to the construction phase, but can be logistically difficult. Geophysics can help close the gaps between local point information and produce subsurface images. An approach that combines seismic refraction tomography and electrical resistivity tomography has been tested at the Äspö Hard Rock Laboratory (HRL). The aim was to detect fracture zones in a well-known but logistically and, from a measuring perspective, challenging area. The presented surveys cover a water passage along a part of a tunnel that connects surface facilities with an underground test laboratory. The tunnel is approximately 100 m below and 20 m east of the survey line and gives evidence for one major and several minor fracture zones. The geological and general test site conditions, e.g. with strong powerline noise from the nearby nuclear power plant, are challenging for geophysical measurements. Co-located positions for seismic and ERT sensors and source positions are used on the 450 m long underwater section of the 700 m long profile. Because of a large transition zone that appeared in the ERT result and the missing coverage of the seismic data, fracture zones at the southern and northern part of the underwater passage cannot be detected by separated inversion. A simple synthetic study shows significant three dimensional artefacts corrupting the ERT model that have to be taken into account while interpreting the results. A structural coupling cooperative inversion approach is able to image the northern fracture zone successfully. In addition, previously unknown sedimentary deposits with a significant large thickness are detected in the otherwise unusually well documented geological environment. The results significantly improve imaging of some geologic features, which would have been not detected or misinterpreted otherwise, and combines the images by means of cluster analysis to a conceptual subsurface model.

scholarly journals Application of the Variety-Generator Approach to Searches of Personal Names in Bibliographic Data Bases--Part 2. Optimization of Key-Sets, and Evaluation of Their Retrieval Efficiency

1974 ◽  
Vol 7 (3) ◽  
pp. 201
Author(s):  
Dirk W. Fokker ◽  
Michael F. Lynch
Keyword(s):  
Information Systems ◽  
Data Base ◽  
Variable Length ◽  
Data Bases ◽  
Personal Names ◽  
Fixed Length ◽  
Bibliographic Data ◽  
Retrieval Efficiency ◽  
Types Of Information ◽  
High Degree

<p class="p1">Keys consisting of variable-length chamcter strings from the front and rear of surnames, derived by analysis of author names in a particular data base, am used to provide approximate representations of author names. When combined in appropriate ratios, and used together with keys for each of the first two initials of personal names, they provide a high degree of discrimination in search.</p> <p class="p1">Methods for optimization of key-sets are described, and the performance of key-sets varying in size between <span class="s1">150 </span>and <span class="s1">300 </span>is determined at file sizes of up to <span class="s1">50,000 </span>name entries. The effects of varying the proportions of the queries present in the file are also examined. The results obtained with fixed-length keys are compared with those for variable-length keys, showing the latter to be greatly superior.</p> <p class="p1">Implications of the work for a variety of types of information systems are discussed.</p>

scholarly journals Siderophore Production by Pseudomonas stutzeri under Aerobic and Anaerobic Conditions

2007 ◽  
Vol 73 (18) ◽  
pp. 5857-5864 ◽  
Author(s):  
Sofia A. Essén ◽  
Anna Johnsson ◽  
Dan Bylund ◽  
Karsten Pedersen ◽  
Ulla S. Lundström
Keyword(s):  
Mass Spectrometry ◽  
Hard Rock ◽  
Bacterial Culture ◽  
Pseudomonas Stutzeri ◽  
Siderophore Production ◽  
Anaerobic Conditions ◽  
Rock Laboratory ◽  
Molecular Masses ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT The siderophore production of the facultative anaerobe Pseudomonas stutzeri, strain CCUG 36651, grown under both aerobic and anaerobic conditions, was investigated by liquid chromatography and mass spectrometry. The bacterial strain has been isolated at a 626-m depth at the Äspö Hard Rock Laboratory, where experiments concerning the geological disposal of nuclear waste are performed. In bacterial culture extracts, the iron in the siderophore complexes was replaced by gallium to facilitate siderophore identification by mass spectrometry. P. stutzeri was shown to produce ferrioxamine E (nocardamine) as the main siderophore together with ferrioxamine G and two cyclic ferrioxamines having molecular masses 14 and 28 atomic mass units lower than that of ferrioxamine E, suggested to be ferrioxamine D2 and ferrioxamine X1, respectively. In contrast, no siderophores were observed from anaerobically grown P. stutzeri. None of the siderophores produced by aerobically grown P. stutzeri were found in anaerobic natural water samples from the Äspö Hard Rock Laboratory.

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