| 1. |
- Brown, Paul, et al.
(författare)
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Solubility of Radium and Strontium Sulfate across the Temperature Range of 0 to 300℃
- 2014
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Ingår i: Uranium Mining and Hydrogeology 2014. - 9783319110592 ; , s. 553-563
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Konferensbidrag (refereegranskat)abstract
- Solubility constant data for radium and strontium (celestite) sulfate has been determined across the temperature range of 0 to 300℃ based on the available literature data for these two phases as well as similar data for calcium (anhydrite) and barium (barite) sulfate for which solubility constant data is available acrossthe same temperature range. The thermodynamic data for the phases have been determined by assuming that the solubility constants are a function of the inverse ofabsolute temperature with a constant, but non-zero, heat capacity change. The solubility for all phases shows a peak with respect to temperature, with the temperature at which the peak occurs increasing as the alkaline earth metals become heavier. The heat capacity change is a function of the ionic radius of the alkaline earth metal ion whereas the enthalpy of reaction at 25℃ is related to the peak at which the maximum solubility occurs. The entropy of reaction at 25℃ is related to the solubility constant and the derived enthalpy of reaction at that temperature.
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| 2. |
- Hedström, Hanna, 1983, et al.
(författare)
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A study of the Arrhenius behavior of the co-precipitation of radium, barium and strontium sulfate
- 2013
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 298:2, s. 847-852
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Tidskriftsartikel (refereegranskat)abstract
- Co-precipitation of radium, barium and strontium is an important process in many contexts, such as uranium mining, oil extraction and in the safety assessment of a final repository for used nuclear fuel. Co-precipitation to a solid solution is possible since radium, barium and strontium act as chemical analogues. In this work the co-precipitation of radium, barium and strontium was studied and the kinetic behavior of the co-precipitation process was investigated. It was shown that radium, barium and strontium co-precipitate congruently and that the precipitation followed an Arrhenius behavior and the Arrhenius parameters for the systems was determined. When studying the differences of the Arrhenius constants by using a student t test (95 % confidence interval) it was observed that the only significant difference in the activation energy, E (a), is between radium and barium and between radium and strontium respectively, the pure strontium having the larger activation energy in comparison. This is most likely coupled to the metal ion size; since the hydration waters are more strongly bound, which leads to them having a slower exchange rate, which in turn effects the rate of co-precipitation to the metal these reactions will be slower.
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| 3. |
- Hedström, Hanna, 1983, et al.
(författare)
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Radon capture with silver exchanged zeolites
- 2012
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Ingår i: Radiochimica Acta. - : Walter de Gruyter GmbH. - 0033-8230 .- 2193-3405. ; 100:6, s. 395-399
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Tidskriftsartikel (refereegranskat)abstract
- To enable laboratory work with larger amounts of Ra-226 and its decay products, e.g., Rn-222 and its daughters, these need to be captured in order to avoid unnecessary alpha contamination of the laboratory work space and ventilation systems. In this study, radon gas was pumped through a column filled with the silver exchanged zeolite called "silver exchanged molecular sieves 13X" (Ag84Na2[(AlO2)(86)(SiO2)(106)]. xH(2)O). After exposure to radon, the radioactivity of the zeolite was measured repeatedly using high resolution gamma spectrometry. It was shown that radon was captured and retained in the silver exchanged zeolite. The zeolites' ability to retain radon was decreased by formation of metallic silver, caused by ionizing radiation. However, the zeolite was regenerated by heating and its radon capture ability was restored. The daughters of radon are not in gas phase and will hence stay on the column.
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| 4. |
- Ramebäck, Henrik, 1967, et al.
(författare)
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The jackknife as an approach for uncertainty assessment in gamma spectrometric measurements of uranium isotope ratios
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 268:16, s. 2535-2538
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Tidskriftsartikel (refereegranskat)abstract
- The jackknife as an approach for uncertainty estimation in gamma spectrometric uranium isotope ratio measurements was evaluated. Five different materials ranging from depleted uranium (DU) to high enriched uranium (HEU) were measured using gamma spectrometry. High resolution inductively coupled plasma mass spectrometry (ICP-SFMS) was used as a reference method for comparing the results obtained with the gamma spectrometric method. The relative combined uncertainty in the gamma spectrometric measurements of the U-238/U-235 isotope ratio using the jackknife was about 10-20% (k = 2), which proved to be fit-for-purpose in order to distinguish between different uranium categories. Moreover, the enrichment of U-235 in HEU could be measured with an uncertainty of 1-2%. (C) 2010 Elsevier B.V. All rights reserved.
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| 5. |
- Ramebäck, Henrik, 1967, et al.
(författare)
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Uncertainty assessment in gamma spectrometric measurements of plutonium isotope ratios and age
- 2012
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 287, s. 56-59
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Tidskriftsartikel (refereegranskat)abstract
- A method for the assessment of the combined uncertainty in gamma spectrometric measurements of plutonium composition and age was evaluated. Two materials were measured. Isotope dilution inductively coupled plasma sector field mass spectrometry (ID-ICP-SFMS) was used as a reference method for comparing the results obtained with the gamma spectrometric method for one of the materials. For this material (weapons grade plutonium) the measurement results were in agreement between the two methods for all measurands. Moreover, the combined uncertainty in all isotope ratios considered in this material (R-Pu238/Pu239, R-Pu240/Pu239, R-Pu241/Pu239, and R-Am241/Pu241 for age determination) were limited by counting statistics. However, the combined uncertainty for the other material (fuel grade plutonium) were limited by the response fit, which shows that the uncertainty in the response function is important to include in the combined measurement uncertainty of gamma spectrometric measurements of plutonium.
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| 6. |
- Torapava, Natallia, 1980, et al.
(författare)
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Recrystallization of Ra-223 with barium sulfate
- 2014
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Ingår i: Journal of Radioanalytical and Nuclear Chemistry. - : Springer Science and Business Media LLC. - 0236-5731 .- 1588-2780. ; 301:2, s. 545-553
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the kinetics of barium sulfate recrystallization has been studied in acidic 0.01 mol dm -3 sodium sulfate solution using Ra-223 and Ba-133 tracers at very low total radium concentration, i. e. less than 10(-13) mol dm(-3). It was found that the system follows the homogeneous recrystallization model and that recrystallization rates, inferred by the decrease of Ra-223 and Ba-133 in the aqueous solution, are fast. Therefore, even at very low concentrations, below the solubility limit, radium will be retained by barium sulfate-a mineral present in the deep underground repository.
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| 7. |
- Vesterlund, Anna, 1980, et al.
(författare)
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Characterization of strong 241Am sources
- 2014
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Ingår i: International Conference on Advances in Nuclear Forensics: Countering the Evolving Threat of Nuclear and Other Radioactive Material out of Regulatory Control, Vienna, IAEA; 07/2014.
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Konferensbidrag (refereegranskat)
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| 8. |
- Vesterlund, Anna, 1980, et al.
(författare)
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On the categorization of uranium materials using low resolution gamma ray spectrometry
- 2013
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 73, s. 54-57
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Tidskriftsartikel (refereegranskat)abstract
- In order to characterize uranium materials during e.g. nuclear safeguards inspections and in initial stages of nuclear forensic investigations, hand-held low resolution gamma ray detection instruments with automatic uranium categorization capabilities may be used. In this paper, simulated response curves for a number of matrices applied on NaI(Tl) scintillation detector spectra show that the result of the categorization is strongly dependent on the physical properties of the uranium material. Recommendations on how to minimize the possibility of misclassification are discussed.
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| 9. |
- Altmaier, M., et al.
(författare)
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TALISMAN - A European Commission FP7 project promoting transnational access to large infrastructures for a safe management of actinides
- 2014
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Ingår i: Plutonium Futures: The Science 2014; Las Vegas; United States; 7 September 2014 through 12 September 2014. - 9781510808089 ; , s. 165-166
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Konferensbidrag (refereegranskat)abstract
- TALISMAN is a large international project funded within the European Commission FP7 EURATOM framework. The aim of TALISMAN is to offer transnational access to large infrastructures for a safe management of actinides. Although clearly focusing on R&D activities from European Union member states, TALISMAN is also open to participation from non-EU countries. TALISMAN is coordinated by CEA (contact by stephane.bourg@cea.fr), supported by a Governing Board and the ExCom. Dedicated studies on Pu containing materials are integral part of TALISMAN. Safety issues are of fundamental importance for the acceptance and sustainable application of nuclear energy. Actinides play a central role in the nuclear fuel cycle from mining, fuel fabrication, energy production, up to reprocessing, partitioning and transmutation treatment of used fuel, and finally the management and disposal of radioactive waste. Fundamental understanding of actinide properties and behavior in fuel materials during the separation processes and in geological repositories is an imperative prerequisite to tackle the related safety issues. Unravelling the complexity of the actinide components of used nuclear fuel certainly represents one of the great challenges in nuclear science. To meet the needs of safe and sustainable management of nuclear energy it is essential to maintain a high level of expertise in actinide sciences both on a European and international level. Educating and training the next generation of scientists and engineers who will contribute to developing safe actinide management strategies is a key mission. Because actinides are radioactive elements and handling requires specific safety measures, their study requires advanced tools and facilities that are only available to a limited extent. Only a few academic and research organisations have the capabilities and licenses to work on actinide elements. From a European perspective it is therefore strategic to coordinate the existing actinide infrastructures in Europe and strengthen the community of scientists working on actinides. Within TALISMAN we offer (for positively evaluated scientific research proposals submitted in reply to a specific TALISMAN call) access to the previous ACTINET Pooled Facilities (CEA Atalante and CEA DPC, France; ITU Laboratories & hot-cells, European Commission; KIT-INE laboratories and KIT-INE beamline, Germany; HZDR-IRE & ROBL, Germany; PSI microXAS Beamline, Switzerland) to which two new facilities have been added: NNL Central Lab in the UK and CHALMERS in Sweden. TALISMAN is also open to scientists and research organizations from outside the European Union. TALISMAN leads and coordinates a network of actinide facilities across Europe, but also manages a network between facilities and users to increase the knowledge for a safer management of actinides. TALISMAN also enhances the efforts made to support education and training issues by continuing the former ACTINET Summer School series and travel grant attributions for attending international conferences like the Plutonium Futures series. The TALISMAN project website is regularly updated and offers detailed information on all TALISMAN activities at http://www.talisman-project.eu. This is including contact addresses, TALISMAN newsletters, announcements and description of open and forthcoming calls for transnational user access and indicates several other options to perform actinide research within the TALISMAN context.
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| 10. |
- Aneheim, Emma, 1982, et al.
(författare)
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A TBP/BTBP-based GANEX Separation Process. Part 1: Feasibility
- 2010
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Ingår i: Solvent Extraction and Ion Exchange. - : Informa UK Limited. - 0736-6299 .- 1532-2262. ; 28:4, s. 437-458
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Tidskriftsartikel (refereegranskat)abstract
- A GANEX (Group ActiNide EXtraction) separation system for transmutation has been developed. In this separation process the actinides should be extracted as a group from the lanthanides and the fission and corrosion/activation products. This can be achieved by combining BTBP (bis-triazine-bipyridine) with TBP (tri-butyl phosphate) in cyclohexanone. From 4M nitric acid this organic system extracts the actinides (log(DAm) = 2.19, log(DPu) = 2.31, log(DU) = 1.03, log(DNp) = 0.53) and also separates them from the lanthanides (log(DLa) = -2.0, log(DCe) = -1.72, log(DNd) = -1.05, log(DSm) = -0.18, log(DEu) = -0.02). One problem encountered is that some of the fission and corrosion products are also extracted. The new system however still looks feasible.
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