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ISI Web of Knowledge Page 1 (Articles 1 -- 30) [ 1 ]
Record 1 of 30 Author(s): Billamboz, N (Billamboz, Nicolas); Grivet, M (Grivet, Manuel); Foley, S (Foley, Sarah); Baldacchino, G (Baldacchino, Gerard); Hubinois, JC (Hubinois, Jean-Charles) Title: Radiolysis of the polyethylene/water system: Studies on the role of hydroxyl radical Source: RADIATION PHYSICS AND CHEMISTRY, 79 (1): 36-40 JAN 2010 Abstract: The role of hydroxyl radical on polyethylene degradation under aqueous conditions has been studied. The reactivity of HO center dot towards PE is highlighted by pulse radiolysis experiments on a PE powder suspension in water using the thiocyanate competition technique. Infrared analysis of PE films irradiated in the presence of water is performed. Solutions have been either degassed with Ar, in order to remove O-2 which would react with the PE. or N2O which enhances the production of HO center dot radicals. Oxygenated groups and double bond groups created at the surface of PE are characterized using IR analysis, and the results for both saturated solution systems are compared. (C) 2009 Elsevier Ltd. All rights reserved. ISSN: 0969-806X DOI: 10.1016/j.radphyschem.2009.08.016
Record 2 of 30 Author(s): Taguchi, M (Taguchi, Mitsumasa); Baldacchino, G (Baldacchino, Gerard); Kurashima, S (Kurashima, Satoshi); Kimura, A (Kimura, Atsushi); Sugo, Y (Sugo, Yumi); Katsumura, Y (Katsumura, Yosuke); Hirota, K (Hirota, Koichi) Title: Transient absorption measurement system using pulsed energetic ion Source: RADIATION PHYSICS AND CHEMISTRY, 78 (12): 1169-1174 DEC 2009 Conference Title: 2nd Asia-Pacific Symposium on Radiation Chemistry Conference Date: AUG 29-SEP 01, 2008 Conference Location: Tokyo, JAPAN Conference Host: Waseda Univ, Int Conf Ctr Abstract: This article reports a highly sensitive transient absorbance measurement system using pulsed energetic ions. The ions were pulsed by a beam chopper, which was synchronized with the cyclotron, and accelerated to the desired energy around 18 MeV/u. H, He, C and Ne ions can be used for the transient absorption measurement. The optical system can measure an absorbance smaller than 1.0 x 10(-4) in the wavelength range of 400-740 nm. (C) 2009 Elsevier Ltd. All rights reserved. ISSN: 0969-806X DOI: 10.1016/j.radphyschem.2009.05.019
Record 3 of 30 Author(s): Fermvik, A (Fermvik, Anna); Berthon, L (Berthon, Laurence); Ekberg, C (Ekberg, Christian); Englund, S (Englund, Sofie); Retegan, T (Retegan, Teodora); Zorz, N (Zorz, Nicole) Title: Radiolysis of solvents containing C5-BTBP: identification of degradation products and their dependence on absorbed dose and dose rate Source: DALTON TRANSACTIONS, (32): 6421-6430 2009 Abstract: Solvents intended for the separation of trivalent actinides from trivalent lanthanides in spent nuclear fuel have been irradiated with gamma-radiation. The solvents initially contained 0.005 M C5-BTBP dissolved in either hexanol or cyclohexanone and they were exposed to doses up to 20 kGy. Identification of degradation products was done using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). Structures were suggested for a number of degradation products and the relative intensity of the peaks in the MS spectra was estimated. It was clear that the content of the original molecule, C5-BTBP, decreased with dose, while the content of the various degradation products increased. It was also shown that both the choice of diluent and the dose rate (Gy/h) affect the amount of degradation products formed. A degradation scheme was proposed for the radiolytic degradation of C5- BTBP. ISSN: 1477-9226 DOI: 10.1039/b907084b
Record 4 of 30
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Author(s): Le Rouzo, G (Le Rouzo, G.); Lamouroux, C (Lamouroux, C.); Dauvois, V (Dauvois, V.); Dannoux, A (Dannoux, A.); Legand, S (Legand, S.); Durand, D (Durand, D.); Moisy, P (Moisy, P.); Moutiers, G (Moutiers, G.) Title: Anion effect on radiochemical stability of room-temperature ionic liquids under gamma irradiation Source: DALTON TRANSACTIONS, (31): 6175-6184 2009 Abstract: Radiochemical stability of imidazolium-based ionic liquids constituted of the BuMeIm(+) cation and associated with four commonly used anions (X-: Tf2N-, TfO-, PF6- and BF4-) has been investigated under gamma irradiation for high irradiation doses (up to 2.0 MGy). The anion effect has been examined by quantifying the radiolytic yields of disappearance for cation and anions and by identifying corresponding radiolysis products with several analytical techniques. On the one hand, a large number of radiolysis products are formed throughout the irradiation in ionic liquid solutions, resulting from reactions of primary generated species of cation and anion by indirect radiolysis. Primary generated species can react together throughout the irradiation by indirect radiolysis to form numerous radiolysis products in small quantities, indicating that several complex degradation pathways are involved for these radiation doses. This degradation pattern has been confirmed by identification of numerous gaseous radiolytic products. On the other hand, quantitative studies show that radiochemical stabilities of ionic liquids are in the same range of values as systems envisioned in nuclear fuel reprocessing with relatively low hydrogen yields. Indeed, this present work emphasizes the suitability of ionic liquids for applications in the nuclear fuel cycle. ISSN: 1477-9226 DOI: 10.1039/b903005k
Record 5 of 30 Author(s): Alam, M (Alam, Mohamad); Miserque, F (Miserque, Frederic); Taguchi, M (Taguchi, Mitsumasa); Boulanger, L (Boulanger, Loic); Renault, JP (Renault, Jean Philippe) Title: Tuning hydrogen production during oxide irradiation through surface grafting Source: JOURNAL OF MATERIALS CHEMISTRY, 19 (24): 4261-4267 2009 Abstract: Hydrogen production by radiolysis of water absorbed on solid is a major problem for nuclear waste management. In the present study, we demonstrate that controlling extreme surface properties of the irradiated material allows a direct tuning of the hydrogen production under irradiation. We achieve this control on a model system (silica fibers) using liquid phase atomic layer deposition (ALD) of titanium or zirconium oxide. The hydrogen production is strongly inhibited by the deposition of a subnanometric layer of titanium oxide, whereas it is amplified upon zirconium oxide grafting. ISSN: 0959-9428 DOI: 10.1039/b901936g
Record 6 of 30 Author(s): Beuve, M (Beuve, M.); Colliaux, A (Colliaux, A.); Dabli, D (Dabli, D.); Dauvergne, D (Dauvergne, D.); Gervais, B (Gervais, B.); Montarou, G (Montarou, G.); Testa, E (Testa, E.) Title: Statistical effects of dose deposition in track-structure modelling of radiobiology efficiency Source: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 267 (6): 983-988 MAR 2009 Conference Title: 7thTriennial International Symposium on Swift Heavy Ions in Matter Conference Date: JUN 02-05, 2008 Conference Location: Lyon, FRANCE Abstract: Ion-induced cell killing has been reported to depend on the irradiation dose but also on the projectile parameters. In this paper we focus on two approaches developed and extensively used to predict cell survival in response to ion irradiation: the Local Effect Model and the Katz Model. These models are based on a track-structure description summarized in the concept of radial dose. This latter is sensitive to ion characteristics parameters and gives to both models the ability to predict some important radiobiological features for ion irradiations. Radial dose is however an average quantity, which does not include stochastic effects. These radiation-intrinsic effects are investigated by means of a Monte Carlo simulation of dose deposition. We show that both models are not fully consistent with the nanometric and microscopic dose deposition statistics. (C) 2009 Elsevier B.V. All rights reserved. ISSN: 0168-583X DOI: 10.1016/j.nimb.2009.02.016
Record 7 of 30 Author(s): Adoui, L (Adoui, L.); Cassimi, A (Cassimi, A.); Gervais, B (Gervais, B.); Grandin, JP (Grandin, J.-P.);
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Guillaume, L (Guillaume, L.); Maisonny, R (Maisonny, R.); Legendre, S (Legendre, S.); Tarisien, M (Tarisien, M.); Lopez-Tarifa, P (Lopez-Tarifa, P.); Politis, MF (Politis, M.-F.); du Penhoat, MAH (du Penhoat, M.-A. Herve); Vuilleumier, R (Vuilleumier, R.); Gaigeot, MP (Gaigeot, M.-P.); Tavernelli, I (Tavernelli, I.); Alcami, M (Alcami, M.); Martin, F (Martin, F.) Title: Ionization and fragmentation of water clusters by fast highly charged ions Source: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 42 (7): Art. No. 075101 APR 14 2009 Abstract: We study the dissociative ionization of water clusters by impact of 12 MeV/u Ni25+ ions. Cold target recoil ion momentum spectroscopy (COLTRIMS) is used to obtain information about stability, energetics and charge mobility of the ionized water clusters. An unusual stability of the H9O4+ ion is observed, which could be the signature of the so-called Eigen structure in gas-phase water clusters. From the analysis of coincidences between charged fragments, we conclude that charge mobility is very high and is responsible for the formation of protonated water clusters, (H2O)(n)H+, that dominate the mass spectrum. These results are supported by Car-Parrinello molecular dynamics and time-dependent density functional theory simulations, which also reveal the mechanisms of such mobility. ISSN: 0953-4075 Article Number: 075101 DOI: 10.1088/0953-4075/42/7/075101
Record 8 of 30 Author(s): Colombani, J (Colombani, J.); Herbette, G (Herbette, G.); Rossi, C (Rossi, C.); Joussot-Dubien, C (Joussot-Dubien, C.); Labed, V (Labed, V.); Gilardi, T (Gilardi, T.) Title: Leaching of Plasticized PVC: Effect of Irradiation Source: JOURNAL OF APPLIED POLYMER SCIENCE, 112 (3): 1372-1377 MAY 5 2009 Abstract: Highly irradiated (2-26 MGy) polyvinyl chloride (PVC) was leached in an alkaline solution to investigate the impact of high doses on the leaching process and on the nature of the leaching products. The results show that leaching is controlled by diffusion phenomena as described by Fick's second law. The apparent diffusion coefficient (D-a) of plasticized PVC leaching products can be calculated for each sample. Irradiation at high dose causes D-a to diminish; this can be attributed to cross-linking and grafting reactions occurring during irradiation. The material microstructure thus becomes less permeable during radiolysis, which slows down the migration of species. Organic products of leaching are plasticizers contained in plasticized PVC or their degradation products. The main organic leaching products are phthalic ions formed by the hydrolysis of phthalic esters in alkaline leaching solution. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 1372-1377, 2009 ISSN: 0021-8995 DOI: 10.1002/app.29612
Record 9 of 30 Author(s): Louit, G (Louit, Guillaume); Hanedanian, M (Hanedanian, Mikael); Taran, F (Taran, Frederic); Coffigny, H (Coffigny, Herve); Renault, JP (Renault, Jean Philippe); Pin, S (Pin, Serge) Title: Determination of hydroxyl rate constants by a high-throughput fluorimetric assay: towards a unified reactivity scale for antioxidants Source: ANALYST, 134 (2): 250-255 2009 Abstract: We describe in this article the development of a new method for the determination of rate constants of reaction of the hydroxyl radical, generated by radiolysis of water, with almost any possible molecule. It has been designed to provide a fast and reliable screening of antioxidant banks using microplates. Our particular approach is based on the use of the coumarin molecule as a competitor against the tested molecules: after a fast pulse of low dose irradiation, the fluorescence of 7-hydroxycoumarin produced by the oxidation of coumarin is measured and is inversely proportional to the scavenging ability of the tested antioxidant. We have validated our protocol using 32 molecules whose rate constants with HO center dot had already been evaluated and found a good agreement between our rate constants and the latter ones. The scopes and limitations of our method, as well as those of other rate constant determination methods, are discussed. ISSN: 0003-2654 DOI: 10.1039/b813871k
Record 10 of 30 Author(s): Muzeau, B (Muzeau, B.); Jegou, C (Jegou, C.); Delaunay, F (Delaunay, F.); Broudic, V (Broudic, V.); Brevet, A (Brevet, A.); Catalette, H (Catalette, H.); Simoni, E (Simoni, E.); Corbel, C (Corbel, C.)
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Title: Radiolytic oxidation of UO2 pellets doped with alpha-emitters (Pu-238/239) Source: JOURNAL OF ALLOYS AND COMPOUNDS, 467 (1-2): 578-589 JAN 7 2009 Abstract: To assess the impact of alpha radiolysis of water on the oxidative dissolution Of UO2 under anoxic conditions, two series of plutonium-doped samples (specific alpha activity 385 and 18 MBq g(UO2)(-1)) Were fabricated, characterized and leached in water of varying complexity (pure water, carbonated water, dissolved hydrogen). Given the very high reactivity of these samples in the presence of air and in order to minimize any prior surface oxidation, a strict experimental protocol was developed based on high-temperature annealing in Ar+4% H-2 With preleaching cycles. Failure to follow this protocol prevents absolute quantification of oxidation of the UO2 surface by water radiolysis in solutions. Preoxidation of the pellet surface can lead to uranium release in solution that is dependent on the alpha particle flux, revealing initial oxidation by radiolysis in air including potential traces of water. This makes difficult the accurate quantification of the radiolytic oxidation in water solutions. Controlling the initial surface condition of the samples finally allowed us to demonstrate that radiolytic oxidation in water- saturated media is governed by several threshold effects for which the main parameters are the sample alpha activity and the hydrogen concentration. (C) 2008 Elsevier B.V. All rights reserved. ISSN: 0925-8388 DOI: 10.1016/j.jallcom.2007.12.054
Record 11 of 30 Author(s): Baldacchino, G (Baldacchino, G.); Maeyama, T (Maeyama, T.); Yamashita, S (Yamashita, S.); Taguchi, M (Taguchi, M.); Kimura, A (Kimura, A.); Katsumura, Y (Katsumura, Y.); Murakami, T (Murakami, T.) Title: Determination of the time-dependent OH-yield by using fluorescent probe. Application to heavy ion irradiation Source: CHEMICAL PHYSICS LETTERS, 468 (4-6): 275-279 JAN 22 2009 Abstract: This Letter reports a sensitive method using HPLC-Fluorescence detection of *OH in liquid water under high-energy heavy ion irradiation. The coumarin-3-carboxylic-acid (3CCA) molecule was selected for probing *OH and providing the fluorescent 7-hydroxy-coumarin-3-carboxylic-acid (7OH-3CCA). Since the concentration limit achievable is better than 1 nM, the radiolytic yields were determined with a sensitivity of 2 x 10(9) mol/J for 4.8 GeV-C-12(6+) of and 20 GeV-Ar-40(18+) in the ns time range. They decrease with the linear energy transfer from 2.8 x 10(7) to 1.3 x 10(7) mol/J (C6+ of 11 eV/nm) and 1.5 x 10(7) to 0.9 x 10(7) mol/J (Ar18+ of 90 eV/nm) which is in agreement with the literature data. (C) 2008 Elsevier B.V. All rights reserved. ISSN: 0009-2614 DOI: 10.1016/j.cplett.2008.12.006
Record 12 of 30 Author(s): Quaranta, A (Quaranta, Annamaria); Zhang, YM (Zhang, Yongmin); Wang, YL (Wang, Yali); Edge, R (Edge, Ruth); Navaratnam, S (Navaratnam, Suppiah); Land, EJ (Land, Edward J.); Bensasson, RV (Bensasson, Rene V.) Title: Single and double reduction of C-60 in 2:1 gamma-cyclodextrin/[60]fullerene inclusion complexes by cyclodextrin radicals Source: CHEMICAL PHYSICS, 354 (1-3): 174-179 DEC 10 2008 Abstract: Spectroscopic and chemical properties of gamma-CD center dot radicals, resulting from the abstraction by HO center dot radicals of hydrogen atoms, have been investigated using pulse radiolysis. The reactions of gamma-CD center dot radicals with C-60 in 2:1 gamma-CD/C-60 inclusion complexes have been Studied in aqueous solutions. It has been demonstrated that the gamma-CD center dot radicals are reducing species producing C-60(center dot-) monoanion radicals, as well as doubly reduced C-60(2-). well characterised by their absorption spectra in the near IR. The oxidation potential of gamma-CD center dot radical is estimated to be more negative than -390 mV vs. NHE. The kinetics of the C-60 reduction by gamma-CD center dot radicals have been determined and compared with kinetics by other reducing species including the solvated electron (e(aq)(-)) and CO2 center dot- radicals. It was observed that the method of preparation of the 2:1 gamma-CD/C-60 inclusion complexes modifies the C-60 reduction mechanism. (C) 2008 Elsevier B.V. All rights reserved. ISSN: 0301-0104 DOI: 10.1016/j.chemphys.2008.10.014
Record 13 of 30 Author(s): Boulin, PF (Boulin, Pierre Francois); Angulo-Jaramillo, R (Angulo-Jaramillo, Rafael); Daian, JF (Daian, Jean-Francois); Talandier, J (Talandier, Jean); Berne, P (Berne, Philippe) Title: Experiments to estimate gas intrusion in Callovo-oxfordian argillites
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Source: PHYSICS AND CHEMISTRY OF THE EARTH, 33: S225-S230 Suppl. 1 2008 Conference Title: 3rd International Meeting on Clays in Natural and Engineered Barriers for Radioactive Waste Confinement Conference Date: SEP 17-20, 2005 Conference Location: Lille, FRANCE Abstract: Gases, especially hydrogen, will be generated by corrosion and radiolysis of high radioactive waste containers in deep geological repositories. Pressure build up resulting from those long-term processes may create a risk of geological barrier fracturation and of potential creation of preferential pathways for radionuclide migration. Good knowledge of gas transfer mechanisms in the potential host rock formations is therefore necessary. The present work focuses on Callovo-oxfordian argillites from the Bure (Meuse, France) underground laboratory operated by Andra, the French national agency for radioactive waste management. Its goal is to understand the pore structure of that rock formation as a first step towards characterizing and modelling gas intrusion and transfer. Our approach was to use various techniques in combination. Firstly, mercury intrusion experiments were made. Besides supplying the classical pore size distribution curve, they bear some resemblance with the real-life problem since mercury (a non-wetting phase) invades the porous structure like a gas would. Secondly, the water vapor sorption curve was measured by submitting initially dry samples to atmospheres with increasing vapor content. Comparison of the mercury intrusion/water vapour sorption data sets yielded information on the connectivity of the pore structure. Thirdly, the gas permeability of dry argillites was measured in a specifically designed set-up, using helium as an acceptable (non-detonating) substitute for hydrogen. The main observation was the existence of a large Klinkenberg effect. Finally, all the available information was used to build and constrain a multi-scale models for the pore network using the XDQ technique. The resulting models were used to predict the properties of the material at various water saturation levels. (C) 2008 Elsevier Ltd. All rights reserved. ISSN: 1474-7065 DOI: 10.1016/j.pce.2008.10.004
Record 14 of 30 Author(s): Tribet, M (Tribet, M.); Toulhoat, N (Toulhoat, N.); Moncoffre, N (Moncoffre, N.); Jegou, C (Jegou, C.); Leturcq, G (Leturcq, G.); Corbel, C (Corbel, C.); Toulhoat, P (Toulhoat, P.) Title: Leaching of a zirconolite ceramic waste-form under proton and He2+ irradiation Source: RADIOCHIMICA ACTA, 96 (9-11): 619-624 2008 Conference Title: 11th International Conference on Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere Conference Date: AUG 26-31, 2007 Conference Location: Munich, GERMANY Abstract: In the hypothesis of a nuclear waste geological disposal, zirconolite is a candidate host material for minor tri-and tetra-valent actinides arising from enhanced nuclear spent fuel reprocessing and partitioning. Its chemical durability has been studied here under charged particle-induced radiolysis (He2+ and proton external beams) to identify possible effects on dissolution rates and mechanisms in pure water. Two experimental geometries have been used to evaluate the influence of the following parameters: solid irradiation and total deposited energy. Results on the evolution of the elemental releases due to the enhanced dissolution of the zirconolite Surface during charged particle-induced irradiation of water are presented. Under radiolysis, elemental releases are first kinetically controlled. When the titanium and the zirconium releases reach (or exceed) their corresponding hydroxide solubility limits, the zirconolite dissolution becomes thermodynamically controlled. ISSN: 0033-8230 DOI: 10.1524/ract.2008.1545
Record 15 of 30 Author(s): Baldacchino, G (Baldacchino, G.) Title: Pulse radiolysis in water with heavy-ion beams. A short review Source: RADIATION PHYSICS AND CHEMISTRY, 77 (10-12): 1218-1223 OCT-DEC 2008 Conference Title: International Symposium on Charged Particle and Photon Interactions with Matter Conference Date: NOV 06-09, 2007 Conference Location: Tokai, JAPAN
Abstract: This article presents a short review of the studies in radiation chemistry of liquid water with heavy ions, which have used pulse radiolysis methods during the last 20 years. The interests and the difficulties of developing this kind of experiment are depicted. The linear energy transfer (LET) effect is the main topic of these studies. The earliest effects close to the structure of the deposited energy can be observed directly by transient absorption
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spectroscopy by following the hydrated electron, the superoxide radical produced in the absence of molecular oxygen and the hydroxyl radical, which still requires the use of scavenger. Finally, the results can be compared to the heterogeneous chemical processes in the time range of 1 ns to 1 mu s described by Monte Carlo simulations. The absolute values of the radiolytic yields are still uncertain because of the dosimetry accuracy. The future aspects of the method are discussed in terms of new types of particle accelerators giving better time resolutions. (c) 2008 Elsevier Ltd. All rights reserved. ISSN: 0969-806X DOI: 10.1016/j.radphyschem.2008.05.033
Record 16 of 30 Author(s): Berlu, L (Berlu, Lilian); Rosa, G (Rosa, Gaelle) Editor(s): Shuh, DK; Chung, BW; AlbrechtSchmitt, T; Gouder, T; Thompson, JD Title: A model for the study of molecules radiochemical decomposition by actinides materials Source: ACTINIDES 2008 - BASIC SCIENCE, APPLICATIONS AND TECHNOLOGY, 1104: 215-220 2008 Book series title: MATERIALS RESEARCH SOCIETY SYMPOSIUM PROCEEDINGS Conference Title: Symposium on Actinides 2008 - Basic Science, Applications and Technology held at the 2008 MRS Spring Meeting Conference Date: MAR 25-28, 2008 Conference Location: San Francisco, CA Abstract: The radiochemical decomposition of molecules in storage environment which could lead to the corrosion of container or the formation of dangerous gas mixtures is a critical problem for radioactive materials. The complexity of the chemical system makes numerical models necessary for the reproduction mechanisms and the prediction of phenomena. In this study, a mathematical model for the dose rate distribution in external medium surrounding an alpha emitter actinide material has been proposed. The model has been implemented in a Monte Carlo scheme. An evaluation of the dose rate in the surrounding medium as a function of the sample size was shown and a discussion of the expected reactivity was made. ISSN: 0272-9172 ISBN: 978-1-60511-074-5
Record 17 of 30 Author(s): Ferry, M (Ferry, M.); Ngono-Ravache, Y (Ngono-Ravache, Y.); Picq, V (Picq, V.); Balanzat, E (Balanzat, E.) Title: Irradiation of atactic polystyrene: Linear energy transfer effects Source: JOURNAL OF PHYSICAL CHEMISTRY B, 112 (35): 10879-10889 SEP 4 2008 Abstract: Atactic glassy polystyrene (PS) has been irradiated in anoxic conditions by electron and ion beams. The induced modifications were followed, in situ, by Fourier transform infrared spectroscopy (FTIR). In-film modifications and hydrocarbon gas release were followed. In-situ measurements allowed one to avoid any spurious oxidation of the films after irradiation and also permitted Studying in detail the evolution with dose of the FTIR spectra. The data were quantitatively analyzed, and we present a complete analysis of the effects of the Linear Energy Transfer (LET) on the radiation chemical yields of several radiation-induced modifications (alkynes, allenes, alkenes, benzene, and disubstituted benzenes). For a better understanding of the LET effects, the in-film modifications are compared to H-2 release data from the literature and to our measurements of hydrocarbon gaseous molecule yields obtained by us. The overall destruction yield becomes very significant at high LET, and the radiation sensitivity of this aromatic polymer merges with typical values of aliphatic polymers: the radiation resistance conferred at low LET to polystyrene by the phenyl side groups is lost at high LET. This loss of radiation resistance equally affects the aromatic and aliphatic moieties. Monosubstituted alkynes are created above a LET threshold, whereas the other radiation-induced modifications are observed in the whole LET range. Several observations indicate that the phenyl ring is broken at high LET. Comparison of the alkyne yield in PS, polyethylene, and polycarbonate as well as the formation of nitrile bonds in poly(vinylpyridine-co-styrene) are consistent with a cleavage of the phenyl ring as the prominent source of alkynes. As the competing damage mechanisms do not have the same LET evolution, the relative importance of a specific modification on the global damage depends on LET. Some (benzene and disubstituted benzenes) dominate at low LET, while others (in-film alkyne and acetylene release) dominate at high LET. ISSN: 1520-6106 DOI: 10.1021/jp801865s
Record 18 of 30
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Author(s): Gael, B (Gael, Batifol); Christophe, D (Christophe, Douche); Christophe, S (Christophe, Sejournant) Title: Tritium release reduction and radiolysis gas formation Source: FUSION SCIENCE AND TECHNOLOGY, 54 (1): 205-208 JUL 2008 Conference Title: 8th International Conference on Tritium Science and Technology Conference Date: SEP 16-21, 2007 Conference Location: Rochester, NY Abstract: At CEA Valduc, the usual tritiated waste container is the steel drum. It allows good release reduction performance for middle activity waste but in some cases tritium outgassing from the waste drums is too high. It was decided to overpackage each drum in a tighter container called the over-drum. According to good safety practices it was also decided to measure gas composition evolution into the over-drum in order to defect hydrogen formation over time. After a few months, a significant release reduction was observed. Additionally there followed contamination reduction in the roof storage building rainwater. However hydrogen was also observed in some over- drums, in addition to other radiolysis products. Catalyst will be added to manage the hydrogen risk in the over- drums. ISSN: 1536-1055
Record 19 of 30 Author(s): Renault, JP (Renault, Jean Philippe); Vuilleumier, R (Vuilleumier, Rodolphe); Pommeret, S (Pommeret, Stanislas) Title: Hydrated electron production by reaction of hydrogen atoms with hydroxide ions: A first-principles molecular dynamics study Source: JOURNAL OF PHYSICAL CHEMISTRY A, 112 (30): 7027-7034 JUL 31 2008 Abstract: The solvated electron production by reaction between the H atom and the hydroxide anion was studied using Density Functional Theory based first-principles molecular dynamics. The simulation reveals a complex mechanism, controlled by proton transfers in the coordination sphere of the hydroxide and by the diffusion of the H atom in its solvent cavity. We formulate the hypothesis, based on a coupling between classical and first-principles molecular dynamics, that these two processes give rise to a lag time for the reaction that would explain the H atom extremely small reactivity compared to other radical species. Furthermore, the reaction observed gives an original insight in excess electron solvation. ISSN: 1089-5639 DOI: 10.1021/jp800269s
Record 20 of 30 Author(s): Mun, C (Mun, C.); Cantrel, L (Cantrel, L.); Madic, C (Madic, C.) Title: Oxidation of ruthenium oxide deposits by ozone Source: RADIOCHIMICA ACTA, 96 (6): 375-384 2008 Abstract: During a hypothetical severe accident on a nuclear Pressurized Water Reactor (PWR), the formation of highly radiotoxic RuO4(g) may occur in the reactor containment building, resulting from the interactions of ruthenium oxide deposits with the oxidising medium induced by air radiolysis. Consequently, there is a risk that the gaseous ruthenium tetroxide could be dispersed into the environment through containment leakages; therefore data concerning the behaviour of ruthenium oxide deposits is of primary importance for safety studies. An experiment has been designed to study the interactions of ruthenium oxide deposits with ozone, formed by air radiolysis. Experimental results have shown that the oxidation reaction leading to the formation of RuO4(g) occurred to a large extent. An oxidation kinetic rate law has been determined, in dry and moist air, for ruthenium deposited onto painted substrates, representative of the inner surfaces of PWR's. This law, combined with tetroxide stability data [1], will allow a first evaluation of ruthenium revolatilisation phenomenon, possibly occurring in the containment during a severe accident. ISSN: 0033-8230 DOI: 10.1524/ract.2008.1501
Record 21 of 30 Author(s): Adoui, L (Adoui, L.); Legendre, S (Legendre, S.); Tarisien, M (Tarisien, M.); Cassimi, A (Cassimi, A.); Galassi, ME (Galassi, M. E.); Giglio, E (Giglio, E.); Gervais, B (Gervais, B.) Editor(s): Becker, U; Moshammer, R; Mokler, P; Ullrich, J Title: High LET highly charged ion-induced ionization and fragmentation of water molecules and clusters - art. no. 012023
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Source: XXV INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC AND ATOMIC COLLISIONS, 88: 12023-12023 2007 Book series title: JOURNAL OF PHYSICS CONFERENCE SERIES Conference Title: 25th International Conference on Photonic, Electronic and Atomic Collisions Conference Date: JUL 25-31, 2007 Conference Location: Freiburg, GERMANY Abstract: Kinematically complete experiments lead to very substantial progress in the understanding of decay dynamics of multiply charged molecular ions. This paper is devoted to the study of dissociative ionization of water molecules and clusters induced by highly charged ions. We will present first how experimental results determined in the gas phase can provide information about the physical stage of liquid water radiolysis. Second, we will discuss strong bond cleavage selectivity in ion-induced dissociation of deuterium tagged water molecule. Finally, we will present first promising results about water cluster dissociative ionization. Stability, energetics and charge mobility in the charged cluster will be briefly discussed. ISSN: 1742-6588
Record 22 of 30 Author(s): Brunet, F (Brunet, F.); Charpentier, T (Charpentier, T.); Le Caer, S (Le Caer, S.); Renault, JP (Renault, J. -P.) Title: Solid-state NMR characterization of a controlled-pore glass and of the effects of electron irradiation Source: SOLID STATE NUCLEAR MAGNETIC RESONANCE, 33 (1-2): 1-11 JAN-FEB 2008 Abstract: Controlled-pore glasses (CPGs) are silica-based materials which provide an adequate model system for a better understanding of the radiation chemistry of glasses, especially under nanoscopic confinement. This paper presents a characterization of a nanoporous CPG before and after electron irradiation using multinuclear solid-state magnetic resonance (NMR). H-1 MAS NMR has been used for studying the surface proton sites and it is observed that the irradiation leads to a dehydration of the material. Accordingly, concerning the silicon sites near the surface, the observed variation of the Q(4), Q(3) and Q(2) species from H-1-Si-29 CPMAS spectra shows an increase of the surface polymerization under irradiation, implying in majority a Q(2) to Q(3)/Q(4) conversion mechanism. Similarly, H-1-O-17 CPMAS measurements exhibit an increase of Si-O-Si groups at the expenses of Si-OH groups. In addition, modifications of the environment of the residual boron atoms are also put in evidence from B-11 MAS and MQMAS NMR These data show that MAS NMR methods provide sensitive tools for the characterization of these porous glasses and of the tiny modifications occurring under electron irradiation. (C) 2008 Elsevier Inc. All rights reserved. ISSN: 0926-2040 DOI: 10.1016/j.ssnmr.2007.12.001
Record 23 of 30 Author(s): Raffi, J (Raffi, J.); Talbi, S (Talbi, S.); Dolo, JM (Dolo, J. -M.); Garcia, T (Garcia, T.); Kister, J (Kister, J.) Title: Advances in solid alanine radiolysis understanding Source: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, 69 (3): 904-910 MAR 2008 Abstract: To better understand the composite character of irradiated alanine ESR spectra, a comparative study of few simple amino acids is performed in order to identify the different radio-induced radicals and their proportions. A dedicated spin-trapping method coupled with High Performance Liquid Chromatography (HPLC) is developed and carried out on irradiated alanine, glycine and valine; labeled or not. This study leads us to obtain different isolated trapped radical spectra where hyperfine coupling constants could be evaluated. For alanine, only two species are identified with relative proportions around 97 and 3% in contradiction with recent published articles. The main species has a particularity on its hyperfine coupling constants when labeled carbons are used. Very high hyperfine coupling constants are observed with the carboxylic acid function carbon for the three studied amino acid. (C) 2007 Elsevier B.V. All rights reserved. ISSN: 1386-1425 DOI: 10.1016/j.saa.2007.05.040
Record 24 of 30 Author(s): Hubert, S (Hubert, Solange); Heisbourg, G (Heisbourg, Guillaume); Dacheux, N (Dacheux, Nicolas); Moisy, P (Moisy, Philippe)
Title: Effect of inorganic ligands and hydrogen peroxide on ThO2 dissolution. Behaviour of Th0.87Pu0.13O2
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during leaching test Source: INORGANIC CHEMISTRY, 47 (6): 2064-2073 MAR 17 2008 Abstract: The dissolution of ThO2 powdered samples was examined in various conditions of pH and concentration of anions in the leachate. The first part of this paper describes the influence of pH on the dissolution of ThO2 in both nitric and hydrochloric media. The partial order relative to the proton concentration and the apparent normalized dissolution rate constants were determined. The second part of the paper describes the influence of other ligands such as perchlorate, chloride, sulfate, and hydrogen peroxide on the dissolution kinetics (at pH 1). An increase of R- L was observed correlatively with the increase of complexing affinity of the ligand with Th. While nitric and hydrochloric media, which are weakly complexing, lead to R-L values with the same order of magnitude as those for perchlorate media, the presence of sulfate or peroxide in the leachate significantly enhances the dissolution of ThO2. Consequently, the dissolution mechanism can be explained by the weakening of Th-O bonds through the formation of surface complexes at the solid/liquid interface, which enhance the detachment and thus accelerate the global dissolution. In addition, the dissolution of Th0.87Pu0.13O2 solid solution was also examined. The increase of the dissolution kinetics of Th0.87Pu0.13O2, in comparison with that of ThO2, is considered to be caused by the presence of hydrogen peroxide formed by radiolysis of the leachate. Moreover, the redox properties of plutonium in acidic media, like disproportionation of Pu(IV) and Pu(V) and reduction of Pu(VI) and Pu(IV) in Pu(III) by H2O2, probably increase the dissolution of plutonium. ISSN: 0020-1669 DOI: 10.1021/ic702065z
Record 25 of 30 Author(s): Bouniol, P (Bouniol, P.); Bjergbakke, E (Bjergbakke, E.) Title: A comprehensive model to describe radiolytic processes in cement medium Source: JOURNAL OF NUCLEAR MATERIALS, 372 (1): 1-15 JAN 15 2008 Abstract: Basic mechanisms controlling the radiolysis in cementitious matrices are reviewed in the specific context of the gamma irradiation, in closed system without upper vapour space, at 25 degrees C, with a pore solution representative of a Portland cement paste. A general survey of data corresponding to each phenomenological area is given, particularly with a list of reactions for alkaline medium and a revised description of equilibria related to calcium hydroxide. Simulations as a function of dose rate, liquid saturation in the porosity or initial amount of H-2 are carried out with the CHEMSIMUL code. They show the existence of several ways in the radiolysis regulation involving calcium peroxide octahydrate precipitation, a law of mass action through the bulk general system, or the particular activation of an Allen's type chain reaction. This latter seems faster in alkaline medium (pH > 13) where radicals H-center dot and OH center dot are, respectively, replaced by e(aq)(-) and O center dot-. Excepted when a strong reducing agent is initially present, 02 is normally produced by radiolysis and CaO2 center dot 8H(2)O cannot be responsible of its disappearance. (c) 2006 Published by Elsevier B.V. ISSN: 0022-3115 DOI: 10.1016/j.jnucmat.2006.10.004
Record 26 of 30 Author(s): Bosse, E (Bosse, Emilie); Berthon, L (Berthon, Laurence); Zorz, N (Zorz, Nicole); Monget, J (Monget, Julie); Berthon, C (Berthon, Claude); Bisel, I (Bisel, Isabelle); Legand, S (Legand, Solene); Moisy, P (Moisy, Philippe) Title: Stability of [MeBu3N][Tf2N] under gamma irradiation Source: DALTON TRANSACTIONS, (7): 924-931 2008 Abstract: The stability of the ionic liquid [MeBu3N][Tf2N], dry or after contact with water (where [MeBu3N](+) is the methyltributylammonium cation and [Tf2N](-) is the bistriflimide anion), was studied under Cs-137 gamma irradiation in argon and in air. In a quantitative study with an absorbed dose of 2 MGy this ionic liquid was highly stable regardless of the radiolysis conditions. The radiolytic disappearance yields determined by ESI-MS were -0.38 and -0.25 mu mol J(-1) for the cation and anion, respectively. ESI-MS, NMR, and liquid chromatography coupled with ESI-MS identified a large number of degradation products in very small quantities for the same dose. The cation radicals were formed by the loss of a Bu-lozenge group, the Me-lozenge group, or two H-lozenge atoms to form a double bond with the butyl chain. Radiolysis of the anion produced mainly F-lozenge and CF3 lozenge radicals. The anion radicals recombined with the cation to form a wide range of secondary degradation products regardless of the radiolysis conditions. ISSN: 1477-9226 DOI: 10.1039/b713661g
Record 27 of 30
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Author(s): Colombani, J (Colombani, Juliette); Labed, V (Labed, Veronique); Joussot-Dubien, C (Joussot-Dubien, Christophe); Perichaud, A (Perichaud, Alain); Raffi, J (Raffi, Jacques); Kister, J (Kister, Jacky); Rossi, C (Rossi, Claude) Title: High doses gamma radiolysis of PVC: Mechanisms of degradation Source: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 265 (1): 238-244 DEC 2007 Conference Title: 7th International Symposium on Ionizing Radiation and Polymers Conference Date: SEP 23-28, 2006 Conference Location: Antalya, TURKEY Abstract: Anaerobic and aerobic radiolysis mechanisms of poly(vinyl chloride) were investigated using electron spin resonance (ESR), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR) and size exclusion chromatography (SEC). PVC samples have been irradiated by gamma rays (Co-60) at high doses (up to 4 MGy) and at room temperature. High dose anaerobic radiolysis of PVC induced several modifications in polymer. Alkyl radicals are formed, and then these radicals induced the formation of polyenic radicals. 13 C NMR spectra have also shown the formation of polyenic sequences and crosslinking reactions. The modifications induced in PVC irradiated under aerobic condition are different. ESR spectra have shown that peroxyl radicals are formed. Propagating reactions from peroxyl radicals are mainly composed by P-scission reactions. These P-scission reactions involved the decrease of average molecular weight and the formation of aldehydes, acids chloride and/or carboxylic acids. From all these results, anaerobic and aerobic mechanisms of degradation by PVC radiolysis are proposed. (C) 2007 Elsevier B.V. All rights reserved. ISSN: 0168-583X DOI: 10.1016/j.nimb.2007.08.053
Record 28 of 30 Author(s): Le Caer, S (Le Caer, S.); Renault, JP (Renault, J. P.); Mialocq, JC (Mialocq, J. -C.) Title: Hydrogen peroxide formation in the radiolysis of hydrated nanoporous glasses: A low and high dose rate study Source: CHEMICAL PHYSICS LETTERS, 450 (1-3): 91-95 DEC 14 2007 Abstract: Hydrated nanoporous controlled pore glasses have been irradiated with gamma-rays or 10 MeV electrons and the formation of hydrogen peroxide (H2O2) upon irradiation has been quantified. Under gamma-irradiation the H2O2 formation is strongly enhanced as compared to bulk water, evidencing an efficient energy transfer from silica to confined water. In the case of high dose rate irradiations using 10 MeV electrons, the H2O2 radiolytic yields are much smaller and comparable to the value obtained in bulk water: no energy transfer is any more possible. In all cases, H2O2 is the oxidant counterpart to H-2 in the radiolysis of hydrated glasses. (C) 2007 Elsevier B.V. All rights reserved. ISSN: 0009-2614 DOI: 10.1016/j.cplett.2007.10.102
Record 29 of 30 Author(s): Poulesquen, A (Poulesquen, A.); Jegou, C (Jegou, C.) Title: Influence of alpha radiolysis of water on UO2 matrix alteration: Chemical/transport model Source: NUCLEAR TECHNOLOGY, 160 (3): 337-345 DEC 2007
Abstract: A combined transport and radiolysis model is proposed in this paper to predict the oxidation/dissolution Of UO2 under alpha radiolysis of water. The UO2-water interface is divided into an arbitrary number of layers. The Chemsimul kinetic code is used for radiolysis calculations in each layer, and the modeling of transport between the layers is based on Fick's law. The calculation proceeds in an iterative way, and an alpha dose rate profile is taken into account as input data. To limit the calculation time, which depends on the computer capacity and the duration of the leaching experiment described, a compromise between the thickness and the number of cells has to be found. At present, simulations of leaching experiments lasting several days cannot be carried out because of the very long calculation time. However, the calculation has been compared with experimental results obtained under irradiation at high flux levels of a UO2-water interface subjected to a beam of He2+ particles generated by a cyclotron. Owing to computer time limitation, calculations are carried out by considering 200 layers, each 10 mu m thick, to simulate 1-h experiments. In the experimental geometry (monoenergetic linear alpha beam), the alpha dose rate profile is well described by a summation of Bragg curves. The comparison relates to experiments performed in aerated and deaerated media at a high flux of 3.3 X 10(10) alpha center dot cm(-2)center dot s(-1) and 3.3 X10(10) alpha center dot cm(-2) center dot s(-1). The calculated uranium content in solution is three times lower than the experimental value, and the hydrogen peroxide concentration is ten times lower in aerated media. In deaerated media, however, the comparison is quite good. Finally, a calculation was carried out with a large imposed dissolved hydrogen
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concentration in solution to check the inhibition of matrix dissolution. The release of uranium in solution is relatively high despite the hydrogen concentration in solution because of the primary formation of hydrogen peroxide. This is probably because of a lack of knowledge concerning the inhibitor mechanism under alpha radiolysis (influence of the surface under alpha irradiation, hydrogen activation, validity of primary radiolytic yield in presence of H-2, etc.), which is not taken into account in our calculations. ISSN: 0029-5450
Record 30 of 30 Author(s): Leoni, E (Leoni, E.); Corbel, C (Corbel, C.); Cobut, V (Cobut, V.); Simon, D (Simon, D.); Feron, D (Feron, D.); Roy, M (Roy, M.); Raquet, O (Raquet, O.) Title: Electrochemical behaviour of gold and stainless steel under proton irradiation and active RedOx couples Source: ELECTROCHIMICA ACTA, 53 (2): 495-510 DEC 1 2007 Abstract: Model experiments are reported where proton beams delivered by the cyclotron located at CERI (CNRS- Orleans) are used for irradiating AISI 316L/water and Au/water high purity interfaces with 6 MeV protons. The free exchange potentials at the interfaces are recorded as a function of time at room temperature in situ before, under, and after proton irradiation. The evolutions are compared to those calculated for the Nernst potentials associated with the radiolytic RedOx couples. It is shown how the comparison gives evidence that five radiolytic species - O-2 center dot, H2O2, HO2-, HO2 center dot and O-2(center dot-) - exchange electrons at the Au interfaces in a range of dose rates that vary over three orders of magnitudes, i.e. 0.0048
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