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[en] Isotopically enriched 129I (85% 129I and 15% 127I) targets were irradiated with a beam of 660-MeV protons at the JINR DLNP Phasotron and cross sections of formation of 74 residual products were determined using the γ-spectrometry method. Here, we analyze all these data using eleven different models, realized in eight codes: LAHET (Bertini, ISABEL, INCL+ABLA, and INCL+RAL options), CASCADE, CEM95, CEM2k, LAQGSM+GEM2, CEM2k+GEM2, LAQGSM+GEMINI, an d CEM2k+GEMINI, in order to validate the tested models against the expe ri mental data and to understand better the mechanisms for production of residual nuclei. We find that most of the codes are fairly reliable in predicting cross sections for nuclides not too far away in mass from the targets, but differ greatly in the deep spallation, fission, and fragmentation regions. None of the codes tested here except GEMINI allow fission of nuclei as light as iodine, therefore the best agreement with the 129I data, especially in the A=40-90 region, is shown by the codes CEM2k and LAQGSM when they are merged with GEMINI. We conclude that none of the codes tested here are able to reproduce well all these data and all of them need to be fu rther improved ; development of a better universal evaporation/fission model should be of a high priority.
[en] Future transmutation of some selected long-lived radionuclides into short-lived and stable nuclides could drastically reduce the long-term radiotoxicity of radioactive waste. However, this will require further development of the reprocssing technology with the aim of a loss-free separation of the radionuclides to be transformed. In addition to several minor actinides the long-lived fission product I-129 is of the greatest relevance for future transmutation. This study first describes the behaviour and distribution of I-129 in the fuel cycle. According to the present state of the art in reprocessing technology, the I-129 contained in spent fuel elements can be completeley transferred into the dissolver off-gas and efficiently adsorbed on silver-nitrate-impregnated silica (AC 6120). For future transmutation, the I-129 should again be separated selectively and as completely as possible from the AC 6120 adsorption matrix. Experimental studies show that a quantitative recovery (>99%) of the iodine is possible by simple chemical processes. The resultant possibilities of producing a target for transmutation are being discussed. (orig.)
[de]Durch zukuenftige Transmutation einiger ausgewaehlter langlebiger Radionuklide in kurzlebige bzw. stabile Nuklide liesse sich das Langzeitgefaehrdungspotential des radioaktiven Abfalls drastisch reduzieren. Voraussetzung ist allerdings eine weiterzuentwickelnde Wiederaufarbeitung mit dem Ziel einer verlustfreien Abtrennung der umzuwandelnden Radionuklide. Neben einigen Transuranelementen ist auch das langlebige Spaltprodukt Iod-129 ein potentieller Kandidat fuer die Transmutation. In diesem Bericht wird zunaechst das Verhalten von Iod-129 und dessen Verteilung im Brennstoffkreislauf zusammenfassend dargestellt. Es zeigt sich, dass nach dem heutigen Stand der Wiederaufarbeitungstechnik das in den abgebrannten Brennelementen enthaltene Iod vollstaendig in das Aufloeserabgas ueberfuehrt wird und effizient an Silbernitrat-impraegnierte Kieselsaeure (AC 6120) adsorbiert werden kann. Experimentelle Untersuchungen zeigen, dass es mit Hilfe einfacher chemischer Verfahren gelingt, das Iod wieder quantitativ (>99%) von der Adsorptionsmatrix abzutrennen. Die sich daraus ergebenden Moeglichkeiten einer Targetgewinnung fuer die Transmutation werden diskutiert. (orig.)
[en] Determination of the physical, chemical and radiological properties of wastes intended for disposal in any radwaste repository represents one of the major goals of every country dealing with nuclear facilities. In most disposal facilities the long lived α- and β-emitting radionuclides have the most restrictive inventory limits, because they do not decay appreciably in the lifetime of the facility. One of the most restrictive radionuclides is 129I, a fission product with long half- life, high mobility and biological hazard for the human body. The purpose of this paper is to present and to compare the 129I results obtained by two different Institutes, using different measurement methods on a wide variety of low level radioactive waste streams generated at the Paks NPP. The Institute of Nuclear Technique of the Technical and Economical University of Budapest analyzed 129I in a sequential scheme that included preconcentration, neutron activation, post-irradiation chemistry and counting of the shorter-lived 130I activation product, while the Institute of Nuclear Research of the Hungarian Academy of Sciences used radiochemical separation followed by low-energy direct gamma-ray spectrometry. The results show a good correlation and prove the availability of both measurement methods.(author)
[en] Spatial distribution of oceanic "1"2"9I inventory presented here is based on collection of data from published literatures coupled with model calculation using ArcGIS software tools. A total of 363 thiessen polygons were created for the oceans in order to cover the tremendous variability in distribution of "1"2"9I data range. The results indicate that total "1"2"9I oceanic inventory is approximately 7310 kg, which is mainly stored in the region of the North Atlantic and the Arctic Oceans. The concentrations of "1"2"9I in the oceans are 3-4 orders of magnitude higher than the pre-anthropogenic level reflecting effects of post 1945 anthropogenic activities. (author)
[en] The objective of this document is to report on early success for sequestering 129I. Sorption coefficients (Kd) for I- and IO3- onto delafossites, spinels and layered metal hydroxides were measured in order to compare their applicability for sequestering 129I. The studies were performed using a dilute fluid composition representative of groundwater indigenous to the Yucca mountain area. Delafossites generally exhibited relatively poor sorption coefficients (< 101.7 mL/g). In contrast, the composition of the layered hydroxides significantly affects their ability to sorb I. Cu/Al and Cu/Cr layered hydroxide samples exhibit Kd's greater than 103 mL/g for both I- and IO3-
[en] SRNL has considerable experience in designing, engineering, and operating systems for removing iodine-129 (I-129) and ruthenium-106 (Ru-106) from waste streams that are directly analogous to the Advanced Liquid Processing System (ALPS) waste streams. SRNL proposes to provide the technical background and design and engineering support for an improved I-129 and Ru-106 removal system for application to ALPS on the Fukushima Daiichi Nuclear Power Station (NPS).
[en] The goal of the project was to utilize the knowledge accumulated by the team, in working with minerals for chloride wastes and biological apatites, toward the development of advanced waste forms for immobilizing 129I and mixed-halide wastes. Based on our knowledge, experience, and thorough literature review, we had selected two minerals with different crystal structures and potential for high chemical durability, sodalite and CaP/PbV-apatite, to form the basis of this project. The focus of the proposed effort was towards: (i) low temperature synthesis of proposed minerals (iodine containing sodalite and apatite) leading to the development of monolithic waste forms, (ii) development of a fundamental understanding of the atomic-scale to meso-scale mechanisms of radionuclide incorporation in them, and (iii) understanding of the mechanism of their chemical corrosion, alteration mechanism, and rates. The proposed work was divided into four broad sections. deliverables. 1. Synthesis of materials 2. Materials structural and thermal characterization 3. Design of glass compositions and synthesis glass-bonded minerals, and 4. Chemical durability testing of materials.
[en] The direct conversion of iodine-bearing sorbents into a stable waste form is a research topic of interest to the US Department of Energy. The removal of volatile radioactive 129I from the off-gas of a nuclear fuel reprocessing facility will be necessary in order to comply with the regulatory requirements that apply to facilities sited within the United States (Jubin et al., 2012a), and any iodine-containing media or solid sorbents generated by this process would contain 129I and would be destined for eventual geological disposal. While recovery of iodine from some sorbents is possible, a method to directly convert iodineloaded sorbents to a durable waste form with little or no additional waste materials being formed and a potentially reduced volume would be beneficial. To this end, recent studies have investigated the conversion of iodine-loaded silver mordenite (I-AgZ) directly to a waste form by hot isostatic pressing (HIPing) (Bruffey and Jubin, 2015). Silver mordenite (AgZ), of the zeolite class of minerals, is under consideration for use in adsorbing iodine from nuclear reprocessing off-gas streams. Direct conversion of I-AgZ by HIPing may provide the following benefits: (1) a waste form of high density that is tolerant to high temperatures, (2) a waste form that is not significantly chemically hazardous, and (3) a robust conversion process that requires no pretreatment.
[en] The monitoring of long-lived radionuclides is of great importance in the context of the surveillance of nuclear facilities, during their operation as well as during their decommissioning. This is especially true for radionuclides of rather volatile elements, such as chlorine and iodine, the main interest being in 36Cl and 129I. Liquid Scintillation Counting (LSC) is a widely used measurement technique especially for the determination of 36Cl that requires a thorough and selective sample preparation in order to give accurate results. Sample preparation methods frequently employed such as volatilization and/or repeated precipitation steps can be rather elaborate and time consuming. Therefore, an attempt has been made to develop an 'easy to use' extraction chromatographic resin that allows extraction, and subsequent separation, of chloride and iodide from pretreated environmental and decommissioning samples for their determination via LSC. First results of the characterization of the resin including Dw values of Cl-, I- and potential interferents, and of the method development are presented as well as the result of the analysis of a simulated real sample. (author)