Neutrons radiolysis

Katsumura Y, Sunaryo G, Hiroishi D, Ishiqure K (1998) Fast neutron radiolysis of water at elevated temperatures relevant to water chemistry. Prog Nucl Energy 32 113-121... 

Relevant to water radiolysis in nuclear reactor, G-values of the water decomposition by fast neutrons have been determined by using a fast reactor at elevated temperatures [59]. Since fast neutron radiolysis is equivalent to proton radiolysis because of the recoil proton formation through the elastic collision of fast neutrons with H2O molecules [60], an alternative approach as a model experiment is the ion beam radiolysis with different LET particles from accelerators at elevated temperatures [61]. 

P. Humrickhouse, P. Wilson, et al., Gamma Shield Design for the Supercritical Water Neutron Radiolysis Experiment, Transactions ofANS, 92, 161-162 (2005)... 

Potential fusion appHcations other than electricity production have received some study. For example, radiation and high temperature heat from a fusion reactor could be used to produce hydrogen by the electrolysis or radiolysis of water, which could be employed in the synthesis of portable chemical fuels for transportation or industrial use. The transmutation of radioactive actinide wastes from fission reactors may also be feasible. This idea would utilize the neutrons from a fusion reactor to convert hazardous isotopes into more benign and easier-to-handle species. The practicaUty of these concepts requires further analysis. 

Sunaryo GR, Katsumura Y, Ishigure K (1995) Radiolysis of water at elevated temperatures-III. Simulation of radiolytic products at 25 and 250°C under the irradiation with y rays and fast neutrons. Rad Phys Chem 45 703-714... 

Kudoh, H. Katsumura, Y. In Ion-Beam Radiation Chemistry in Radiation Chemistry Present Status and Future Trends , Jonah, C.D. Rao, B.S.M., Eds. Elsevier London, 2002 37 pp. Elliot, A.J. Chenier, M.P. Ouellette, D.C. Koslowsky, V.T. J. Phys. Chem. 1996, 100, 9014. McCracken, D.R. Tsang, K.T. Laughton, P.J. Aspects of the Physics and Chemistry of Water Radiolysis by Fast Neutrons and Fast Electrons in Nuclear Reactors . AECL Publication 11895, Atomic Energy of Canada Limited Chalk River, Ontario, 1998. 

The neutrons were obtained from the reactor 4B9(d,n)sB10 and the decompn was studied by DTA. An increase in the rate of decompn was observed by all the forms of radiation mentioned up to doses of 1019 eV/g (1.14R = 6.24xl013 eV/g. About 1020 eVg ( 5xl07R) caused the salt to decomp before the modified transition 0 235°). The conclusion was made that the acceleration of the decompn was due to the presence of radiolysis products... 

Numerous studies have been performed in order to elucidate the structure and the dynamics of confined water using a variety of experimental techniques — NMR, quasi-electron neutron diffraction, IR absorption spectroscopy, or molecular dynamics simulation. Most of these studies use model porous media such as clays, polymer membranes, different types of silica and zeolites. Some of these systems (cf Fig. 2) may be used to study water radiolysis in nanoporous media. 

Irradiation of some solids prior to, or even during, thermal decomposition may have a mariced effect on the kinetics of decomposition [68], Such effects are usually interpreted in terms of the imperfections generated by the treatment. Types of radiation used have ranged from visible light to ionizing radiation to neutrons. Solids whose stabilities have been shown to be particularly sensitive to irradiation include the azides (Chapter 11), the permanganates (Chapter 14) and some metal carboxylates (Chapter 16). Comparisons of kinetics of radiolysis with those of pyrolysis can provide useful mechanistic information. Examples of such comparisons are given in the chapters mentioned above. 

The direct observation of radiation-desorbed gas has sometimes been sought in irradiated sealed ampules containing a catalyst, usually with negative results. Thus no gas was observed in ampules of magnesium oxide or nickel oxide which had received as much as 6 x lO nvt of fast neutrons (57). A surprising observation 152) was that of drops of water in the cold parts of a system in which quartz or aerosyl had been irradiated to about 7 X IQi ev/gm with y-rays at room temperature. The fact that water itself was observed indicates removal as water rather than as products of radiolysis. Measurement of the degree of hydration confirmed that detectable amounts of water had been removed. 

A new type of ceramic membrane electrode that is selective for F" ions has been prepared by sintering LaFg, EuFj, and CaFz at above 1200 °C in an atmosphere of Hf The approximate determination of the F" ion concentration in polluted waters can be made by means of a F ion electrode in the presence of citrate ion however, for an accurate determination a photometric method was applied after separation of F by distillation. The probable composition of the La " -alizarin complexone (H4A)-F complex is said to be La(LaA)4F2. ° Alizarin fluorine blue 5-sulphonate is more soluble in water than the unsulphonated reagent the ternary La -F -complexone absorbs at 583 nm. The application of neutron activation analysis to the determination of fluorine has has been reviewed briefly by Verot and Jaumier. X-Ray photoelectron spectroscopy (p.e.s.) has been used to identify and to provide a quantitative estimate of CF3, CF2, and CF groups on the surface of fluorinated diamond. Proton and deuteron radiolysis of... 

Certain radioactive decay processes can be used to provide a source of gamma radiation for radiolysis. One particularly useful isotope is Co, which is produced by thermal neutron bombardment of Co. Co has a half-life of 5.27 yr and emits gamma radiation with an average energy of 1.2 MeV. Another commonly used gamma source is Cs (half-life 30.17 yr, 0.66 MeV). 

Different categories apply to the hydrogen issue in nuclear reactor containments. During normal operation, small quantities of H2 are generated by radiolysis of the coolant, 44 H2 and 22 O2 molecules per 10 eV of neutron radiation energy. Under accident conditions, significant amounts of hydrogen could be produced due to radiolysis and corrosion reactions. 

Radiolysis of the parent molecules is smaller when a heterogeneous paste consisting of Li2C03 (or other lithium derivatives) mixed with the compound to be labelled is neutron-irradiated. In this case a-particles and tritium atoms leave the solid and enter the liquid... 

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