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Sample records for beam water radiolysis

  1. Radiolysis of boiling water

    Science.gov (United States)

    Yang, Shuang; Katsumura, Yosuke; Yamashita, Shinichi; Matsuura, Chihiro; Hiroishi, Daisuke; Lertnaisat, Phantira; Taguchi, Mitsumasa

    2016-06-01

    γ-radiolysis of boiling water has been investigated. The G-value of H2 evolution was found to be very sensitive to the purity of water. In high-purity water, both H2 and O2 gases were formed in the stoichiometric ratio of 2:1; a negligible amount of H2O2 remained in the liquid phase. The G-values of H2 and O2 gas evolution depend on the dose rate: lower dose rates produce larger yields. To clarify the importance of the interface between liquid and gas phase for gas evolution, the gas evolution under Ar gas bubbling was measured. A large amount of H2 was detected, similar to the radiolysis of boiling water. The evolution of gas was enhanced in a 0.5 M NaCl aqueous solution. Deterministic chemical kinetics simulation elucidated the mechanism of radiolysis in boiling water.

  2. Electrons in water radiolysis

    International Nuclear Information System (INIS)

    The hydrated electron is the main reducing species produced in the radiolysis of water. Many studies have examined its reactivity using pulsed radiolysis techniques and competition kinetics. Data bases list hundreds of rate coefficients for reaction of the hydrated electron with substances ranging from inorganic ions like nitrate to biopolymers like DNA. Although the chemistry of the hydrated electron is often examined, its mechanism of formation and variation in yield are considerable less known, especially under extreme conditions such as in high temperature water or with heavy ion radiolysis. This work will examine various aspects of the radiation chemistry of the hydrated electron beginning with the generation of secondary electrons in primary energy loss events during the passage of ionizing radiation to the radiolytic yields of the hydrated electron produced by different types of radiation. Ion radiation is a 'white light source.' Energy losses range from the minimum excitation energy of the medium up to the kinematic maximum determined by the collision parameters. However, certain energy loss events are more probable than others. The dipole oscillator strength distributions of media essentially give the probability of energy loss events in collisions with no momentum transfer. Dipole oscillator distributions have been constructed from experimental data for a wide variety of materials including all the phases of water. Calculations using cross sections based on dipole oscillator distributions show that the most probable energy loss event in water is only about 20 eV with an average value closer to 60 eV. The preponderance of energy loss events of less than 100 eV means that many low energy electrons are formed by the passage of a single ion. Low energy electrons have short mean free paths and they remain in the vicinity of the primary energy loss events. The spatial distribution of these low energy electrons defines the radial track structure of the incident

  3. Construction of ion beam pulse radiolysis system

    Energy Technology Data Exchange (ETDEWEB)

    Chitose, Norihisa; Katsumura, Yosuke; Domae, Masafumi; Ishigure, Kenkichi; Murakami, Takeshi [Tokyo Univ. (Japan)

    1996-10-01

    An ion beam pulse radiolysis system has been constructed at HIMAC facility. Ion beam of 24 MeV He{sup 2+} with the duration longer than 1 {mu}s is available for irradiation. Three kinds of aqueous solutions, (C{sub 6}H{sub 5}){sub 2}CO, NaHCO{sub 3} and KSCN, were irradiated and the absorption signals were observed. (author)

  4. Yields of water radiolysis products from proton irradiated water

    International Nuclear Information System (INIS)

    The yields of aqueous radiolysis products under the high temperature and pressure regimes relevant to Light Water Reactors are important parameters in the use of chemical models to simulate reactor circuits, as high temperature corrosion requires the oxidising products of water radiolysis in order to sustain the process. The main species of interest are the oxidising radical, OH·, and the molecular product H2O2. The yields of these species from radiolysis of water at temperatures below 100degC have been extensively measured. However these measurements have proved difficult at elevated temperatures and pressures because of the requirements to contain the water safely at high temperature and pressure and yet permit entry of a radiation beam. A major source of radiation in the core of the reactor primary circuit is the neutron flux. However, when neutrons interact with water molecules the dominant process for energy loss is with protons by elastic scattering and the formation of energetic recoil protons which then interact further with the surrounding water molecules by electrostatic interaction. Therefore the neutron radiolysis of water can be well simulated by using protons as the incident radiation. Protons are conveniently produced using a Van de Graaff accelerator and in this work the Harwell Tandem accelerator has been used to produce protons with energies up to 12 MeV. (J.P.N.)

  5. Ion beam pulse radiolysis system at HIMAC

    Energy Technology Data Exchange (ETDEWEB)

    Chitose, N.; Katsumura, Y.; Domae, M.; Ishigure, K. [Tokyo Univ. (Japan); Murakami, T.

    1997-03-01

    An ion beam pulse radiolysis system has been constructed at HIMAC facility. Ion beam of 24MeV He{sup 2+} with the duration longer than 1 {mu}s is available for irradiation. Three kinds of aqueous solutions, (C{sub 6}H{sub 5}){sub 2}CO, NaHCO{sub 3}, and KSCN, were irradiated and the absorption signals corresponding to (C{sub 6}H{sub 5}){sub 2}CO{sup -}, CO{sub 3}{sup -}, and (SCN){sub 2}{sup -} respectively were observed. Ghost signals which interfere with the measurement are also discussed. (author)

  6. Modelling of spatial radiolysis in primary water

    International Nuclear Information System (INIS)

    The radiolysis of water in LWRs (light water-cooled reactors) by gamma, neutron and alpha radiation leads to the production of molecular (H2O2, H2) and radical (H, OH, e-(aq), H+) species. These species subsequently react and achieve steady state concentrations. The concentrations of the oxidizing species (O2, H2O2) and dissolved hydrogen significantly influence the corrosion potential of an alloy exposed to the primary coolant and, hence, affect the resistance of the alloy to localized corrosion and stress corrosion cracking particularly. A common approach to estimate the corrosion potential of in-core components is numerical calculation. The steady state concentrations of dissolved hydrogen, oxygen and hydrogen peroxide are estimated by conventional radiolysis codes. These concentrations are used afterwards to calculate the corrosion potential. However, the analytical expressions employed in the calculations for approximation of the mass transport do not take into account radiolysis in the diffusion layer. This can cause significant errors in the estimation of the corrosion potential even for a simple electrode geometry; hence also for occluded regions like baffle bolt crevices. Therefore, to improve the numerical calculation of radiolysis one should take into account simultaneously mass transport effects and radiolysis. This approach has been called spatial radiolysis calculations. A typical PWR radiolysis model contains some 50 chemical reactions involving some 20 species. The implementation of all these reactions into a finite element code in order to calculate mass transport and radiolysis simultaneously has not been successful

  7. Modeling of water radiolysis at spallation neutron sources

    International Nuclear Information System (INIS)

    In spallation neutron sources neutrons are produced when a beam of high-energy particles (e.g., 1 GeV protons) collides with a (water-cooled) heavy metal target such as tungsten. The resulting spallation reactions produce a complex radiation environment (which differs from typical conditions at fission and fusion reactors) leading to the radiolysis of water molecules. Most water radiolysis products are short-lived but extremely reactive. When formed in the vicinity of the target surface they can react with metal atoms, thereby contributing to target corrosion. The authors will describe the results of calculations and experiments performed at Los Alamos to determine the impact on target corrosion of water radiolysis in the spallation radiation environment. The computational methodology relies on the use of the Los Alamos radiation transport code, LAHET, to determine the radiation environment, and the AEA code, FACSIMILE, to model reaction-diffusion processes

  8. Modeling of water radiolysis at spallation neutron sources

    Energy Technology Data Exchange (ETDEWEB)

    Daemen, L.L.; Kanner, G.S.; Lillard, R.S.; Butt, D.P.; Brun, T.O.; Sommer, W.F.

    1998-12-01

    In spallation neutron sources neutrons are produced when a beam of high-energy particles (e.g., 1 GeV protons) collides with a (water-cooled) heavy metal target such as tungsten. The resulting spallation reactions produce a complex radiation environment (which differs from typical conditions at fission and fusion reactors) leading to the radiolysis of water molecules. Most water radiolysis products are short-lived but extremely reactive. When formed in the vicinity of the target surface they can react with metal atoms, thereby contributing to target corrosion. The authors will describe the results of calculations and experiments performed at Los Alamos to determine the impact on target corrosion of water radiolysis in the spallation radiation environment. The computational methodology relies on the use of the Los Alamos radiation transport code, LAHET, to determine the radiation environment, and the AEA code, FACSIMILE, to model reaction-diffusion processes.

  9. Product yields of water radiolysis with high-energy heavy-ion beams relevant to spatial and temporal track structures

    International Nuclear Information System (INIS)

    Radiolysis of neutral water with high-energy heavy ions has been investigated since the FY 2002. It has been purposed to clarify track structure and its dynamics based on product yields, which are macroscopically measurable. Until the end of the FY 2008, following 4 things has been accomplished: (A) measurement of primary yields of main products (e-aq, ·OH, H2O2), which are defined as yields approximately at 100 ns after irradiation, (B) investigation of temporal behavior of water radicals during ns-μs, (C) development of a sensitive method to determine ·OH yield and its application to heavy-ion irradiations, and (D) investigation of ·OH yields near the Bragg peak. In the FY 2009, experimental data obtained in activity, (D) were carefully discussed based on fragmentation simulation with HIBRAC and PHITS. In addition, two new challenges, (E) utilization of ESR and (F) development of online analysis apparatus of gaseous products, have been started. (author)

  10. Study of water radiolysis in porous media

    International Nuclear Information System (INIS)

    The understanding of the production of H2 in the radiolysis of water confined into pores of concrete is important for the disposal of radioactive waste. In order to describe the mechanisms of water radiolysis in such heterogeneous porous systems we have studied the behaviour under gamma radiation of water confined in porous silica glasses with pores going from 8 to 300 nm of diameter and meso-porous molecular sieves (MCM-41). The radiolytic yields of hydroxyl radicals, hydrated electron and dihydrogen, have been determined with respect to the pore size of materials. The increase of these radiolytic yields compared to those of free water allowed us to show a charge transfer from silica to confined water. On the other hand the kinetics of hydrated electron reactions measured by pulse radiolysis are not modified. (author)

  11. Mathematical modelling of water radiolysis kinetics under reactor conditions

    International Nuclear Information System (INIS)

    Experimental data on coolant radiolysis (RBMK-1000 reactor) were used to construct mathematical model of water radiolysis kinetics under reactor conditions. Good agreement of calculation results with the experiment is noted

  12. Fundamental Aspects of Water Coolant Radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, Hilbert [Studsvik Nuclear AB, Nykoeping (Sweden)

    2006-04-15

    The current state of knowledge of radiolysis in Light Water Reactors (LWR) is presented in this report. High-temperature data for rate constants and primary radiolysis yields have been collected and are shown in tables. Data from different sources have been compared and based on this recommended values have been selected. There is generally a good agreement between g-values for gamma-radiation at ambient temperature from different sources. There are larger discrepancies between results for primary yields from fast neutrons and also for g-values at reactor temperatures. Complete reaction mechanisms, including rate constants at reactor temperatures, from different sources are discussed and shown in tables. Experimentally determined activation energies are also shown, including the temperature range within which they have been determined. In normal cases rate constants at high temperature have been calculated from the rate constant at ambient temperature and the activation energy. Exceptions from this rule are shown and uncertainties have been discussed. The results of a number of radiolysis calculations, carried out for reactor temperatures, are also shown. The results of some sensitivity analyses are discussed. It has been shown that results from radiolysis calculations are rather sensitive to the rate constant ratio k(OH + H{sub 2})/(k(OH + H{sub 2}O{sub 2}). The first reaction leads to recombination, whereas the last reaction leads to decomposition. In some cases reactions which are unimportant at ambient temperature may play a role at reactor temperatures. This may be the case for reactions with a low rate constant at ambient temperature in combination with a high activation energy.

  13. Fundamental Aspects of Water Coolant Radiolysis

    International Nuclear Information System (INIS)

    The current state of knowledge of radiolysis in Light Water Reactors (LWR) is presented in this report. High-temperature data for rate constants and primary radiolysis yields have been collected and are shown in tables. Data from different sources have been compared and based on this recommended values have been selected. There is generally a good agreement between g-values for gamma-radiation at ambient temperature from different sources. There are larger discrepancies between results for primary yields from fast neutrons and also for g-values at reactor temperatures. Complete reaction mechanisms, including rate constants at reactor temperatures, from different sources are discussed and shown in tables. Experimentally determined activation energies are also shown, including the temperature range within which they have been determined. In normal cases rate constants at high temperature have been calculated from the rate constant at ambient temperature and the activation energy. Exceptions from this rule are shown and uncertainties have been discussed. The results of a number of radiolysis calculations, carried out for reactor temperatures, are also shown. The results of some sensitivity analyses are discussed. It has been shown that results from radiolysis calculations are rather sensitive to the rate constant ratio k(OH + H2)/(k(OH + H2O2). The first reaction leads to recombination, whereas the last reaction leads to decomposition. In some cases reactions which are unimportant at ambient temperature may play a role at reactor temperatures. This may be the case for reactions with a low rate constant at ambient temperature in combination with a high activation energy

  14. Radiolysis of water in 'Sarcophagus'

    International Nuclear Information System (INIS)

    Different structure modifications of radiolytic hydrogen sources are discussed. Basic radionuclides, being in the 'Sarcophagus' premises - α-, β-, and γ-irradiations, are taken into account. It is shown, that the β-irradiators (Cs-137 and Sr-90) bring in generating of hydrogen the cardinal contribution. In dependence of nuclear spent material dispersity, soluble forms of radionuclides concentrations, moisture saturation degree of fuel containing materials and water quality the account of hydrogen yield rate is presented. The estimations of the safe content of radiolytic hydrogen in the 'Sarcophagus' premises air in hermeticity and interchange of air degree are offered. 20 refs., 6 tab., 3 figs

  15. Study of the effect of water radiolysis on zirconolite dissolution

    International Nuclear Information System (INIS)

    Zirconolite is one of the matrices foreseen for the confinement of minor actinides in case of deep geological disposal. Indeed, zirconolite (general formula: CaZrxTi3-xO7 (0.8 ≤ x ≤ 1.37)) is able to incorporate rare earth elements and actinides by substitution in calcium and zirconium sites and, moreover, its chemical durability into water is well known. However, in case of deep geological disposal, after a long period, water can reach the confinement matrix and can be radiolysed at the moment of the radionuclide alpha decays. In this work we have thus studied the effects of water radiolysis induced by charged particles (alphas or protons) on the dissolution of a synthetic sintered zirconolite. The formula of this zirconolite is Ca0,8Nd0,2ZrTi1,8Al0,2O7 where Nd simulates the presence of trivalent and tetravalent actinides. We performed the irradiations with external ion beams in two distinct geometries where the fluences ranged from 1015 to 1016 ions.cm-2. In the first geometry the beam stops into water before the surface/water interface. In the second one the beam gets through the sample before stopping at the surface/water interface. The use of these different configurations allows to study the respective influence of parameters such as sample irradiation, Linear Energy Transfer at the surface/water interface or total deposited energy. The irradiations were performed on both crystalline and amorphous zirconolites in pure water or with complexing species such as F-. The sample dissolution has been monitored through the release of cations. The radiolytic production of H2O2 has also been measured. Our results show that the water radiolysis has an effect on the preferential release of Zr, Ti and Nd: for these elements, releases are one or two order of magnitude higher than releases out of radiolysis. Such preferential releases occur whatever the temperature (20 or 50 C), the surface state (crystalline or amorphous) and the experimental conditions (solid

  16. Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam

    International Nuclear Information System (INIS)

    In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 μA). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

  17. Double-decker electron beam accelerator and pulse radiolysis

    International Nuclear Information System (INIS)

    A new concept of double-decker electron beam accelerator is proposed to study the ultra-fast electron-induced reactions in materials by pulse radiolysis. The double-decker electron beams are generated and accelerated in an S-band linear accelerator with different positions in vertical direction and a time delay. One of them is used as a pump electron source and another is converted to light as a probe light source. The time jitter between the pump electron beam and the probe light is thus reduced. The time resolution of pulse radiolysis is expected to be improved. The double-decker electron beam has been generated successfully by injected two laser beam into the photocathode RF gun, which is generated by splitting an Nd:YLF picosecond laser beam. The double-decker electron beams were accelerated up to 31 MeV by an S-band booster linear accelerator and compressed into femtosecond by a magnetic bunch compressor. The profiles of the double-decker electron beams were measured at the exits of the RF gun, the linac and the bunch compressor. The normalized transverse emittance was obtained to be 3.3 mm-mrad for the upper beam and 6.4 mm-mrad for the lower beam at bunch charge of 2nC. The relative energy spread was obtained to be 0.1-0.2% for both beams. The Cherenkov light generated in a suprasil plate and OTR produced on a mirror from the electron beam were also measured. (author)

  18. E-beam radiolysis of aqueous dimethyl phthalate solution

    International Nuclear Information System (INIS)

    To investigate the influence of radiolysis on kinetics and factors of dimethyl phthalate (DMP), the aqueous DMP solution is degraded by 1.8 MeV E-beam, following pseudo-first-order kinetics. The rate constant of DMP degradation decreased exponentially with increasing initial DMP concentration. The DMP is favorably degraded by radical scavengers under its low concentration and alkaline condition. At high doses, the DMP is attacked by eaq- and ·OH, producing monomethyl phthalate, phthalate acid, and a series of aliphatic carboxylic acids, which are completely mineralized into H2O and CO2. (authors)

  19. Study of the radiolysis of water in porous media

    International Nuclear Information System (INIS)

    The understanding of the production of H2 in the radiolysis of water confined into pores of concrete is important for the disposal of radioactive waste. In order to describe the mechanisms of water radiolysis in such heterogeneous porous systems we have studied the behaviour under gamma radiation of water confined in porous silica glasses with pores going from 8 to 300 nm of diameter and meso-porous molecular sieves (MCM-41). The radiolytic yields of hydroxyl radicals, hydrated electron and dihydrogen, have been determined with respect to the pore size of materials. The increase of these radiolytic yields compared to those of free water allowed us to show a charge transfer from silica to confined water. On the other hand the kinetics of hydrated electron reactions measured by pulse radiolysis are not modified. (author)

  20. Kinetics and mechanisms studies on dimethyl phthalate degradation in aqueous solutions by pulse radiolysis and electron beam radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Wu Minghong; Liu, Ning [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Xu Gang, E-mail: xugang@shu.edu.c [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Ma Jing; Tang Liang; Wang Liang [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Fu Haiying [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2011-03-15

    The kinetics and mechanisms of hydroxyl radical/hydrated electron reactions with dimethyl phthalate (DMP) were investigated using pulse radiolysis and electron beam radiolysis techniques. The bimolecular rate constants for the reaction of hydroxyl radical and hydrated electron with DMP were measured to be 3.4x10{sup 9} M{sup -1} s{sup -1} and 1.6x10{sup 10} M{sup -1} s{sup -1} under pulse radiolysis experiments, respectively. The major products after radiation were elucidated by LC/MS/MS and ion chromatography analysis. It was found that DMP degradation had different mechanisms in oxidative and reductive conditions: hydroxyl radical attacked aromatic ring of DMP leading to the fracture of benzene ring, formed a series of byproducts which were completely mineralized while hydrated electron attacked the ester group of DMP, formed the product of phthalic acid in reductive conditions.

  1. Radiolysis of water in the vicinity of passive surfaces

    International Nuclear Information System (INIS)

    Highlights: • HO° production through water radiolysis is enhanced near metal surfaces. • Hastelloy and Stainless steel surfaces can also produce HO° radicals through hydrogen peroxide activation. • There is a deficit in solvated electron production compared to hydroxyl radicals near metal surfaces. - Abstract: Porous metals were used to describe the water radiolysis in the vicinity of metal surfaces. The hydroxyl radical production under gamma irradiation was measured by benzoate scavenging in water confined in a 200 nm porous Ni base alloy or in Stainless steel. The presence of the metallic surfaces changed drastically the HO° production level and lifetime. The solvated electron production was measured via glycylglycine scavenging for Stainless steel and was found to be significantly smaller than hydroxyl production. These observations imply that interfacial radiolysis may deeply impact the corrosion behavior of the SS and Ni based alloys

  2. Primary processes in the radiolysis of water at high temperature

    International Nuclear Information System (INIS)

    A sharp increase of temperature as it is expected in the proximity of radioactive wastes (150 to 200 Celsius degrees) can modify the yields and kinetics of products from water radiolysis. We have used an experimental device based on an optical flow cell coupled to an electron accelerator able to deliver 9 MeV electron on 15 ps long pulses. The radiolysis of water has been studied in the 23 - 350 Celsius degrees temperature range. It is shown that the yield of the hydrated electron increases with temperature and that its kinetics in the 100 ps - 3 ns range is all the slower as the temperature increases. (A.C.)

  3. Current state of knowledge of water radiolysis effects on spent nuclear fuel corrosion

    International Nuclear Information System (INIS)

    Literature data on the effect of water radiolysis products on spent-fuel oxidation and dissolution are reviewed. Effects of gamma radiolysis, alpha radiolysis, and dissolved O2 or H2O2 in unirradiated solutions are discussed separately. Also, the effect of carbonate in gamma-irradiated solutions and radiolysis effects on leaching of spent fuel are reviewed. In addition, a kinetic model for calculating the corrosion rates of UO2 in solutions undergoing radiolysis is discussed. The model gives good agreement between calculated and measured corrosion rates in the case of gamma radiolysis and in unirradiated solutions containing dissolved oxygen or hydrogen peroxide. However, the model fails to predict the results of alpha radiolysis. In a recent study , it was shown that the model gave good agreement with measured corrosion rates of spent fuel exposed in deionized water. The applications of radiolysis studies for geologic disposal of used nuclear fuel are discussed. (author)

  4. Radiolysis of water vapor in the presence of solids

    International Nuclear Information System (INIS)

    An influence of a radiation and doze rate on radiolysis of water vapor at the presence of various cationic forms of aluminosilicate and borosilicate glasses are investigated. The various valency cations of Zr, Rb, P, Ce, Li and Cs were entered into aluminosilicate with mass percents from 3 up to 6. After warming-up of researched substances in ampoules they were filled by a twice-distilled water. Then the ampoules were gamma-irradiated thermostatically by 60Co source with dose rate 1,5-5,0 Gy/sec. The analysis of product of radiolysis was conducted by the gas-chromatographic method. The quantity and life time of electronic defects which are catalytically active centers of the water steam decomposition depend on a dose, temperature and dose rate. 15 refs., 2 tabs., 1 fig

  5. Water radiolysis in a crack tip under gamma ray irradiation

    International Nuclear Information System (INIS)

    Under a non-irradiation condition, oxidant, e.g., O2 and H2O2, in a crack tip is supplied from the bulk water. But under irradiation conditions, even if the diffusion of radiolytic species is not sufficient, direct radiolysis in the crack tip causes high concentrations of radiolytic species. As a result of measurements and Monte Carlo calculation of gamma ray energy deposition, it has been confirmed that the energy deposition rate in the gap water is larger than that in the bulk water. The energy absorption rate increases as the gap width decreases and reaches 1.3 times that in the bulk water. In order to evaluate crack propagation rate for irradiation assisted stress corrosion cracking (IASCC) of stainless steel, a water radiolysis model in a crevice is proposed. A larger energy deposition rate in the crevice water produces many more radiolytic species, which causes high oxidant concentrations in spite of enhanced recombination of the species at the crevice inner surface. So, for IASCC evaluation, crevice water chemistry plays an important role to determine the crack propagation rate under irradiation. (authors)

  6. In-Situ Raman observation of the first step of uranium dioxide weathering exposed to water radiolysis

    International Nuclear Information System (INIS)

    The effect of irradiation is a key point in the knowledge of the behavior of some compounds such as uranium-based ones. Regarding this topic, the authors developed an original in-situ Raman spectroscopy device coupled to a cyclotron ion beam. This original instrument allows observing the kinetics of uranium dioxide weathering by a radiolysis of water. The authors then observed that an altered layer made of Studtite and Schoepite phases grows linearly during the irradiation and extends for several hours after irradiation. Kinetics of production of some molecular species during radiolysis were also reported. (authors)

  7. Water Sorption and Radiolysis Studies for Neptunium Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Icenhour, A.S.

    2004-02-03

    Plans are to convert the {sup 237}Np that is currently stored as a nitrate solution at the Savannah River Site to NpO{sub 2} and then ship it to the Y-12 National Security Complex in Oak Ridge for interim storage. This material will serve as feedstock for the {sup 238}Pu production program, and some will be periodically shipped to the Oak Ridge National Laboratory (ORNL) for fabrication into targets. The safe storage of this material requires an understanding of the radiolysis of moisture that is sorbed on the oxides, which, in turn, provides a basis for storage criteria (namely, moisture content). A two-component experimental program has been undertaken at ORNL to evaluate the radiolytic effects on NpO{sub 2}: (1) moisture uptake experiments and (2) radiolysis experiments using both gamma and alpha radiation. These experiments have produced two key results. First, the water uptake experiments demonstrated that the 0.5 wt % moisture limit that has been typically established for similar materials (e.g., uranium and plutonium oxides) cannot be obtained in a practical environment. In fact, the uptake in a typical environment can be expected to be at least an order of magnitude lower than the limit. The second key result is the establishment of steady-state pressure plateaus as a result of the radiolysis of sorbed moisture. These plateaus are the result of back reactions that limit the overall pressure increase and H{sub 2} production. These results clearly demonstrate that 0.5 wt % H{sub 2}O on NpO{sub 2} is safe for long-term storage--if such a moisture content could even be practically reached.

  8. Water Sorption and Radiolysis Studies for Neptunium Oxides

    International Nuclear Information System (INIS)

    Plans are to convert the 237Np that is currently stored as a nitrate solution at the Savannah River Site to NpO2 and then ship it to the Y-12 National Security Complex in Oak Ridge for interim storage. This material will serve as feedstock for the 238Pu production program, and some will be periodically shipped to the Oak Ridge National Laboratory (ORNL) for fabrication into targets. The safe storage of this material requires an understanding of the radiolysis of moisture that is sorbed on the oxides, which, in turn, provides a basis for storage criteria (namely, moisture content). A two-component experimental program has been undertaken at ORNL to evaluate the radiolytic effects on NpO2: (1) moisture uptake experiments and (2) radiolysis experiments using both gamma and alpha radiation. These experiments have produced two key results. First, the water uptake experiments demonstrated that the 0.5 wt % moisture limit that has been typically established for similar materials (e.g., uranium and plutonium oxides) cannot be obtained in a practical environment. In fact, the uptake in a typical environment can be expected to be at least an order of magnitude lower than the limit. The second key result is the establishment of steady-state pressure plateaus as a result of the radiolysis of sorbed moisture. These plateaus are the result of back reactions that limit the overall pressure increase and H2 production. These results clearly demonstrate that 0.5 wt % H2O on NpO2 is safe for long-term storage--if such a moisture content could even be practically reached

  9. Description and status of BWR water radiolysis model

    International Nuclear Information System (INIS)

    A water radiolysis model for boiling water reactor primary coolant circuits has been developed jointly with Harwell Laboratories. Hydrogen water chemistry plant tests, on which the model is based, started in 1982. Since then, ten plant tests have been completed. Test results indicate that: (1) oxygen concentrations in the steam from plant to plant decreases fairly uniformly with increasing hydrogen concentration; (2) oxygen concentrations in the recirculating water varies widely with increasing hydrogen concentration in the feedwater; and (3) copper significantly suppresses the reduction of oxygen. The radiolysis model was developed to provide predictive conditions in the BWR primary circuit including the core. The objectives of the work are: (1) to develop and calibrate the model against experimental data; (2) to predict the concentration of various radiolytic species and oxygen suppression in various parts of the primary system under hydrogen water chemistry conditions; and (3) to define the role of copper on the reactions. The model considers the thermodynamics and kinetics of homogeneous chemical reactions in eight regions of the reactor and its external circuit. From initial concentrations, the model constructs a set of simultaneous equations to calculate hydrogen, hydrogen peroxide, and oxygen concentrations in various regions. Pilgrim data were used for the initial calibration. The model includes neutron and gamma dose rates in the core region and gamma dose rates in the other various regions, as well as temperature, power levels, heat transfer, steam quality, and gas/liquid transport in the core region, etc. The results of calculations for the oxygen concentrations in the recirculation water as a function of hydrogen concentration in the feedwater show good agreement with the experimental data obtained in a number of reactor tests

  10. Water Sorption and Gamma Radiolysis Studies for Uranium Oxides

    Energy Technology Data Exchange (ETDEWEB)

    Icenhour, A.S.

    2002-02-27

    During the development of a standard for the safe, long-term storage of {sup 233}U-containing materials, several areas were identified that needed additional experimental studies. These studies were related to the perceived potential for the radiolytic generation of large pressures or explosive concentrations of gases in storage containers. This report documents the results of studies on the sorption of water by various uranium oxides and on the gamma radiolysis of uranium oxides containing various amounts of sorbed moisture. In all of the experiments, {sup 238}U was used as a surrogate for the {sup 233}U. For the water sorption experiments, uranium oxide samples were prepared and exposed to known levels of humidity to establish the water uptake rate. Subsequently, the amount of water removed was studied by heating samples in a oven at fixed temperatures and by thermogravimetric analysis (TGA)/differential thermal analysis (DTA). It was demonstrated that heating at 650 C adequately removes all moisture from the samples. Uranium-238 oxides were irradiated in a {sup 60}Co source and in the high-gamma-radiation fields provided by spent nuclear fuel elements of the High Flux Isotope Reactor. For hydrated samples of UO{sub 3}, H{sub 2} was the primary gas produced; but the total gas pressure increase reached steady value of about 10 psi. This production appears to be a function of the dose and the amount of water present. Oxygen in the hydrated UO{sub 3} sample atmosphere was typically depleted, and no significant pressure rise was observed. Heat treatment of the UO{sub 3} {center_dot} xH{sub 2}O at 650 C would result in conversion to U{sub 3}O{sub 8} and eliminate the H{sub 2} production. For all of the U{sub 3}O{sub 8} samples loaded in air and irradiated with gamma radiation, a pressure decrease was seen and little, if any, H{sub 2} was produced--even for samples with up to 9 wt % moisture content. Hence, these results demonstrated that the efforts to remove trace

  11. Radiation-catalytical properties of natural zeolite of mordenite type during radiolysis of water

    International Nuclear Information System (INIS)

    Radiation-catalytic properties of natural zeolite of mordenite type in cation Na+, K+, Ca2+, Ba2+ forms during radiolysis of water molecules were investigated with the use of 60Co γ-radiation (6 Gy/s). Kinetic parameters of radiolysis of water molecules in the presence of these zeolite samples were determined. It was revealed that zeolite of mordenite type catalyzes the radiolysis water molecules, its catalytic activity growing with decrease in ionic radius of the cation in the zeolite composition

  12. Radiolysis ob benzene, toluene and phenol aqueous solutions utilizing high energy electron beam; Radiolisis de benceno, tolueno y fenol en solucion acuosa utilizando haces de electrones

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Vanderhaghen, D.E

    1998-12-31

    In a search for solutions to environmental pollution problems, radiolysis has proved to be an innovative technique for the removal of organic chemical pollutants in aqueous solution. Radiolysis has shown many advantages over many other techniques, as highly reactive species formed in water by ionizing radiation oxidize organic pollutants breaking down organic molecules to final simple products by oxidation to carbon dioxide and water in a complete oxidation. Our work consisted in doing some experiments in radiolysis with simulated polluted water to help us understand this technique and also develop, in a near future, a project for large scale water treatment. Our project includes the application of a Pelletron type Mexican made Electron Accelerator, which will affirm its capability and usefulness in performing investigation in this field of study. Experiments consisted in treating benzene, toluene and phenol aqueous solutions with an Electron Beam (0.48-0.55 MeV; 24 {mu}A). Two concentrations were used for each compound: 5 and 20 ppm (mg/l) for benzene and toluene; 10 and 50 ppm for phenol. Solutions were prepared with pure, mineral free water and two different p H (5.9), in order to study the effect of concentration and p H on removal efficiency, but avoiding the interference of radical scavengers. Results obtained coincide with the ones reported by Cooper, Nickelsen and Kurucz; highly efficient removal was achieved for benzene (>99.8%), toluene (>98.0%) and phenol (>88%). There was no visible important effect of p H on radiolysis efficiency for benzene nor toluene, phenol however, showed lower removal efficiency in acidic conditions. Concentration of aqueous solutions, nevertheless, did show an important effect at low doses for phenol. Results obtained reveal the importance of this technique in water pollution control and water remedial as expressed by Cooper, Nickelsen and Kurucz, who have studied radiolysis of organic compounds and apply this technique in water

  13. Product yields of water radiolysis with heavy ions relevant to track structures

    International Nuclear Information System (INIS)

    Radiolysis of neutral water with high-energy heavy ions has been investigated since the FY 2002, purposing to clarify structure of heavy ions and intra-track dynamics by measuring product yields, which are macroscopically measurable. Until the FY 2009, following 4 things have been accomplished: (A) primary yield measurement, (B) investigation on intra-track dynamics, (C) sensitive determination of Hydroxyl radical (·OH) yields, (D) extension of (C) to the Bragg peak. In the FY 2010, we tried to explain our experimental data obtained in the activity (D) by considering beam quality change in water due to nuclear fragmentations by using PHITS code. A new challenge to develop an online gas analysis system was also promoted. (author)

  14. Water Radiolysis: Influence of Oxide Surfaces on H2 Production under Ionizing Radiation

    Directory of Open Access Journals (Sweden)

    Sophie Le Caër

    2011-02-01

    Full Text Available The radiolysis of water due to ionizing radiation results in the production of electrons, H· atoms, ·OH radicals, H3O+ ions and molecules (dihydrogen H2 and hydrogen peroxide H2O2. A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H2 production. This H2 production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented.

  15. Water radiolysis: Influence of oxide surfaces on H2 production under ionizing radiation

    International Nuclear Information System (INIS)

    The radiolysis of water due to ionizing radiation results in the production of electrons, H and OH radicals, H3O+ ions and molecules (dihydrogen H2 and hydrogen peroxide H2O2). A brief history of the development of the understanding of water radiolysis is presented, with a focus on the H2 production. This H2 production is strongly modified at oxide surfaces. Different parameters accounting for this behavior are presented. (author)

  16. Effect of water α radiolysis on the spent nuclear fuel UO2 matrix alteration

    International Nuclear Information System (INIS)

    In the option of long term storage or direct disposal of nuclear spent fuel, it is essential to study the long-term behaviour of the spent fuel matrix (UO2) in water, in presence of ionizing radiations. This work gives some knowledge elements about the impact of aerated water alpha radiolysis on UO2 alteration. An original experiment method was used in this study. UO2/water interfaces were irradiated by an external He2+ ions beam. The sequential batch dissolution tests on UO2 samples were performed in aerated deionized water, before, during and after a-irradiation under high fluxes. A corrosion product, identified as hydrated uranium peroxide, was formed on the UO2 surface. The uranium release was 3 to 4 orders of magnitude higher under irradiation than out of irradiation. The concentrations of the radiolysis products H2O2 and H3O+ were affected by the uranium oxide surface. They could not only explain the whole uranium release reached during irradiation in water. Leaching experiments on UOX spent fuel samples (with or without the Zircaloy clad) were also performed, in hot cells. The uranium release was relatively small, and H2O2 was not detected in solution. The rates of uranium release in aerated water during one hour were calculated. They were about mg-1.m-2.d-1 for spent fuel and for UO2, and about g-1.m-2.d-1 for UO2 irradiated by He2+ ions. The comparison of the results between the two kinds of experiment shows a difference of the behaviour in water between UO2 irradiated by He2+ ions and spent fuel. Some hypothesis are given to explain this difference. (author)

  17. Risk analysis for a radiolysis gas detonation in an in-pile loop with supercritical water

    International Nuclear Information System (INIS)

    The SCWR (supercritical water reactor) -FQT project is a cooperation between European and Chinese partners aimed to test the fuel SCWR elements under reactor conditions. In the frame of this work the risk of radiolysis gas production in the active range of the test track was assessed. The radiolysis gas could accumulate in an emergency cooling system with stagnating coolant. The ignition of this radiolysis gas could cause pressure peaks that are able to damage the primary coolant circuit. Pressure increase and deformations in case of ignition of accumulated gas were investigated. As piping material the Ti stabilized austenitic steel 08Ch18N10T was assumed, the simulation was performed using the ANSYS code. The results show that pipes without significant wall thickness enhancement cannot withstand the radiolysis gas detonation.

  18. Radiolysis of water at high temperature and pressure conditions: a picosecond pulse radiolysis experiment and numerical simulations

    International Nuclear Information System (INIS)

    Radiolytic products of coolant material under strong radiation field in water-cooled reactors are known to give undesirable effects on nuclear structural materials. Understanding of the fundamental processes will be of great importance for various application fields in water chemistry. Ionization and excitation of water molecules by ionizing radiations initiate very fast physical and chemical processes within μs(10-6 sec), ns (10-9 sec) or even ps (10-12 sec), followed by formation of primary radiolytic species (e-aq, OH, H, H2, H2O2 etc.). Through the processes, the radiation chemical yields (G-values) are supposed to change dynamically depending on time and also on temperature. However, because of so high reactivity (short lifetime), it was difficult to observe experimentally the temporal behaviors (spatially inhomogeneous reactions, called spur diffusion reactions). In this work, the fundamental processes (G-values of the intermediates and the fast reaction kinetics) of the radiolysis of water at high temperature and pressure conditions (HTHP) were investigated by a newly developed picosecond time-resolved pulse radiolysis system, and also by numerical analyses. The results indicated that the hydrated electron (e-aq) in the spur reaction process mainly reacts with OH at room temperature, while that with H3O+ becomes also competitive in subcritical water. Taking the cumulative yield variations (ΔG molec./100eV) into account, it is suggested that historically defined primary G-value of the hydrated electron in subcritical water (G ∼ 3.6 molec./100eV) will be appropriately reexamined to the lower value below 2.7 in neutral pH condition, while it is rather close to it in basic condition. (author)

  19. Sub-picosecond pulse radiolysis and ion beam induced nanowire formation for nanolithography and nanotechnology

    International Nuclear Information System (INIS)

    For an innovation in the future nano-lithographic technique, we clarify crucial factors determining spatial resolutions of the technique by using sub-picosecond pulse radiolysis system bearing, the world highest time resolution at present. The initial separation distance between positive and negative charges (∼ 10 nm at a few tens ps) will be a grave issue for the fabrication of nanoscale patterns in the near future. The pulse radiolysis system is one of the most powerful tools for the understanding of electron beam and X-ray patterning. As a candidate for the real nano-fabrication system using radiations, we report the formation of nanowires that have cylindrical structure of cross-linked polymers by the high-energy ion beam irradiation to thin films of Si backbone polymers. The spatial distribution and size of the isolated nanowires can be fairly controlled by this technique unlike those for producing carbon nanotubes or wires. The radius of the wire varies from a few nm to 15 nm, and is precisely controlled by simply changing the parameters of incident ion beam or molecular sizes of the target polymer. The thickness of the target film determines the length of each wire, which is also under control by the present technique. We introduce some hints of radiations for future technologies in the present paper. (Author)

  20. Influence of chemisorption products of carbon dioxide and water vapour on radiolysis of tritium breeder

    International Nuclear Information System (INIS)

    Highlights: • Chemisorption products affect formation proceses of radiation-induced defects. • Radiolysis of chemisorption products increase amount of radiation-induced defects. • Irradiation atmosphere influence radiolysis of lithium orthosilicate pebbles. - Abstract: Lithium orthosilicate pebbles with 2.5 wt% excess of silica are the reference tritium breeding material for the European solid breeder test blanket modules. On the surface of the pebbles chemisorption products of carbon dioxide and water vapour (lithium carbonate and hydroxide) may accumulate during the fabrication process. In this study the influence of the chemisorption products on radiolysis of the pebbles was investigated. Using nanosized lithium orthosilicate powders, factors, which can influence the formation and radiolysis of the chemisorption products, were determined and described as well. The formation of radiation-induced defects and radiolysis products was studied with electron spin resonance and the method of chemical scavengers. It was found that the radiolysis of the chemisorption products on the surface of the pebbles can increase the concentration of radiation-induced defects and so could affect the tritium diffusion, retention and the released species

  1. Kinetic behaviors of eaq- and ·OH radical in water radiolysis

    International Nuclear Information System (INIS)

    Iodine in the aqueous solution changes its volatile molecule through chemical complexation with free radicals which are formed in water radiolysis. In particular, aqueous electrons (eaq-) and hydroxyl radicals (·OH) play an essential role in iodine behavior. Aqueous electrons react with oxygen and thus produce ·O2- radical which is a strong reductant of molecular iodine. On the other hand, the rate of iodide oxidation depends on the concentration of ·OH that oxidize I- to·I which eventually combines to form I2 (volatile species). Korea Institute of Nuclear Safety (KINS) has been developing the Radio-Active Iodine chemistry Model (RAIM) which simulates iodine behavior in the containment. However, it does not reflect the water radiolysis reaction in detail that has been just applied based on the IMOD (Iodine Model for containment codes) methodology. This paper presents the methods to compute the concentration of water radiolysis products and suggests the application of computing methods by comprehending the behavior of eaq- and ·OH. The calculation code to compute the concentration of water radiolysis products has been developed and validated. Based on the code, the reaction kinetics of aqueous electrons and hydroxyl radicals was investigated. The calculation code developed in the present work can be applied to RAIM for the simplified calculation of water radiolysis products

  2. Determination of primary yields in the alpha radiolysis of alkaline water

    International Nuclear Information System (INIS)

    This work presents a fundamental study of the radiolysis of water within the framework of the management of nuclear waste. During their storage, the packages of cemented radioactive waste are likely to release molecular hydrogen. Indeed, interstitial water undergoes decomposition under irradiation. This phenomenon is called radiolysis. In order to envisage the impact of H2 de-gasification on the security of the installations, it is necessary to determine the primary radiolytic yields in the cementing medium (characterised by a pH ranging between 12 and 14), which provides a basic simulations thus allowing us to obtain both the quantities of gas and the pressure in the pore. Such data is currently not available in the literature. Studies were undertaken with a beam of accelerated helium ions in order to reproduce the conditions of irradiation on solutions at pH = 13 in order to determine a first complete series of radiolytic yields.A more complete study was undertaken on the effects of LET and pH on the yield of molecular hydrogen. The results seem to show that the yield of this primary product is little influenced by pH. Such results were in good agreement with those obtained by Monte-Carlo simulations. These studies have shown that, contrary to γ irradiations, the irradiations with α-particles do not lead to the same characteristic times. The extrapolation of this data with respect to the problem of the packaging of nuclear waste is delicate due to the limited amount of results in the literature and also the chemical and physical complexity of the concretes. (author)

  3. pH dependence of H2O2 in the radiolysis of water

    International Nuclear Information System (INIS)

    The yields of hydrogen peroxide have been experimentally determined in the gamma and heavy ion radiolysis of aerated water at a pH range of 1-14. Experimental results have been combined with diffusion-kinetic track models to obtain a complete mechanistic understanding of the production of hydrogen peroxide over the pH range examined in this work. Hydrogen peroxide yields from the radiolysis of aerate water increase at both high and low pH values as compared to normal water. The production of hydrogen peroxide is found to mainly be due to relatively long time reactions of the hydroperoxyl radical and its conjugate base in the homogeneous radiolysis regime. (author)

  4. Progress and current status in water radiolysis calculation for BWR primary circuit

    International Nuclear Information System (INIS)

    In order to assess the material integrity of the BWR primary components from the viewpoint of material degradation, it has been widely recognized that the radiolysis modeling and the corrosion potential modeling are of vital use for the environmental evaluation of the BWR primary systems. At the last Workshop on LWR Coolant Water Radiolysis and Electrochemistry, summary papers on both modeling discussions were presented. The Hydrogen Water Chemistry Task Team of the Atomic Energy Society of Japan is now discussing standard evaluation procedures of hydrogen water chemistry to guarantee mitigating corrosive conditions for core internals in aged BWRs. This time the progress and current status on the procedures are reported. The radiolysis model should include G-values and reaction rate constants as essential parameters and also deal with plant related parameters such as radiation dose rates. A kind of a sensitivity analysis was performed and the key parameters have been identified. It has been rather a consensus that the radiolysis modeling technique has been well acknowledged as a useful tool. The mixed potential model has been widely used to predict the electrochemical corrosion potential as an important index to evaluate the SCC susceptibility of the materials. In this model the corrosion potential is calculated based on the concentrations of the water radiolysis products and other fluid dynamics parameters as flow velocity, equivalent diameter, etc. Since ECPs at all the necessary points in the BWR primary system are not available, the model calculation is regarded as a necessary tool to predict the effectiveness of environmental mitigation measures such as hydrogen water chemistry. Therefore it is necessary to establish a standard procedure for the evaluation of radiolysis product and the ECP. Recently AECL has issued a data base on the rate constants and G-values. The adoption of those data will be discussed and the comparison of the results to the previous ones

  5. Conditions for critical effects in the mass action kinetics equations for water radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Wittman, Richard S.; Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Smith, Frances N.; Soderquist, Chuck Z.

    2014-12-26

    We report on a subtle global feature of the mass action kinetics equations for water radiolysis that results in predictions of a critical behavior in H2O2 and associated radical concentrations. While radiolysis kinetics has been studied extensively in the past, it is only in recent years that high speed computing has allowed the rapid exploration of the solution over widely varying dose and compositional conditions. We explore the radiolytic production of H2O2 under various externally fixed conditions of molecular H2 and O2 that have been regarded as problematic in the literature – specifically, “jumps” in predicted concentrations, and inconsistencies between predictions and experiments have been reported for alpha radiolysis. We computationally map-out a critical concentration behavior for alpha radiolysis kinetics using a comprehensive set of reactions. We then show that all features of interest are accurately reproduced with 15 reactions. An analytical solution for steady-state concentrations of the 15 reactions reveals regions in [H2] and [O2] where the H2O2 concentration is not unique – both stable and unstable concentrations exist. The boundary of this region can be characterized analytically as a function of G-values and rate constants independent of dose rate. Physically, the boundary can be understood as separating a region where a steady-state H2O2 concentration exists, from one where it does not exist without a direct decomposition reaction. We show that this behavior is consistent with reported alpha radiolysis data and that no such behavior should occur for gamma radiolysis. We suggest experiments that could verify or discredit a critical concentration behavior for alpha radiolysis and could place more restrictive ranges on G-values from derived relationships between them.

  6. Conditions for critical effects in the mass action kinetics equations for water radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Wittman, Richard S.; Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Smith, Frances N.; Soderquist, Chuck Z.

    2014-11-25

    We report on a subtle global feature of the mass action kinetics equations for water radiolysis that results in predictions of a critical behavior in H2O2 and associated radical concentrations. While radiolysis kinetics has been studied extensively in the past, it is only in recent years that high speed computing has allowed the rapid exploration of the solution over widely varying dose and compositional conditions. We explore the radiolytic production of H2O2 under various externally fixed conditions of molecular H2 and O2 that have been regarded as problematic in the literature – specifically, “jumps” in predicted concentrations, and inconsistencies between predictions and experiments have been reported for alpha radiolysis. We computationally map-out a critical concentration behavior for alpha radiolysis kinetics using a comprehensive set of reactions. We then show that all features of interest are accurately reproduced with 15 reactions. An analytical solution for steady-state concentrations of the 15 reactions reveals regions in [H2] and [O2] where the H2O2 concentration is not unique – both stable and unstable concentrations exist. The boundary of this region can be characterized analytically as a function of G-values and rate constants independent of dose rate. Physically, the boundary can be understood as separating a region where a steady-state H2O2 concentration exists, from one where it does not exist without a direct decomposition reaction. We show that this behavior is consistent with reported alpha radiolysis data and that no such behavior should occur for gamma radiolysis. We suggest experiments that could verify or discredit a critical concentration behavior for alpha radiolysis and could place more restrictive ranges on G-values from derived relationships between them.

  7. Study of the consequences of secondary water radiolysis within and surrounding a defective canister

    International Nuclear Information System (INIS)

    A model has been developed to study the effects of secondary water radiolysis caused by dispersed radionuclides in a bentonite buffer surrounding a copper canister. The secondary radiolysis is the radiolysis caused by radionuclides that have been released from the spent fuel and are present either as solutes in the pore-water, as sorbed species on the surface of other minerals, or as secondary minerals. The canister is assumed to be initially defective with a hole of a few millimeters on its wall. The small hole will considerably restrict the transport of oxidants through the canister wall and the release of radionuclides to the outside of the canister. The dissolution of the spent fuel is assumed to be controlled by chemical kinetics at rates extrapolated from experimental studies. Two cases have been considered with the purpose to illustrate the behaviors of both conservative and non-conservative nuclides. The nuclides that are most relevant are those expected to be the dominant α-emitters in the long-term (e.g. 239Pu, 240Pu, 241Am). in the first case it is assumed that there is no precipitation of secondary minerals of the relevant radionuclides inside the canister. In the second case it is assumed that the radionuclide concentration within the canister is controlled by its respective solubility limit. The radionuclide released to the surrounding buffer is then predicted using a mass balance model. The modelling results show that in both cases, the spent fuel will not be oxidized at a rate significantly faster compared to the case where secondary radiolysis is completely neglected. In the first case, however, a large domain of the near-field can be oxidized due to a much faster depletion of reducing minerals in the buffer, compared to the case where secondary radiolysis is neglected. In the second case, the effects of the secondary water radiolysis will be quite limited. Copyright (2001) Material Research Society

  8. Measurement of the hydrogen yield in the radiolysis of water by dissolved fission products

    International Nuclear Information System (INIS)

    Hydrogen from the radiolysis of water by dissolved fission products is stripped from the solution and collected by bubbling CO2 through the solution. Quantitative measurements of the G value for hydrogen show that the yield is essentially the same as would be obtained by external gamma radiolysis of nonradioactive solutions of the same chemical composition. The hydrogen yield can be enhanced by addition of a hydrogen-atom donor, such as formic acid, to the solution. The yield of hydrogen from fission-waste solutions is discussed with respect to the question of whether it represents a significant energy source

  9. The formation of hydrogen in the radiolysis of water in closed volumes

    International Nuclear Information System (INIS)

    By applying the sum total of the elementary reactions involving short-lived particles it is possible to fairly accurately calculate the kinetics of hydrogen formation and of its separation from water, and also to calculate the accumulation of hydrogen peroxide and oxygen during radiolysis of pure water and water solutions at room temperature. This paper describes a semi-empirical method to calculate the kinetics of hydrogen formation for certain cases encountered in nuclear power production. (author)

  10. Water/polyethylene system radiolysis: application to the tritiated water storage in polyethylene bottle

    International Nuclear Information System (INIS)

    This study deals with the validation and the search of the limitations for the storage of tritiated water (HTO) in polyethylene (PE) containers. The hydroxyl radical (HO.), produced during the radiolysis of water, is known for its reactivity toward alkanes in water. Our competition experiments (with SCN- or coumarin) by pulse radiolysis shows the reactivity of HO. with PE, which gives rise to chemical modifications of PE. Some FTIR analysis of PE, irradiated in the presence of water, show that the amounts of C=C, C-O, and C=O functions are more important when the production of HO. is favoured. Moreover the reactivity of eaq- in the presence of PE has also been highlighted by time resolved spectroscopy. The study of permeability of the HTO/PE system shows that the volumetric activity within PE is 104 fold lower than the water activity after a one year immersion in 1853 Ci.L-1 HTO. The MCNP simulation of the irradiation by the β- of the tritium points out that 200 kGy is deposited within the first 250 nanometers of the PE. In spite of an early diffusion these results show a very weak solubility. Furthermore the value of the diffusion decreases following the modifications induced by the β- at the surface. Crosslinking is a parameter that directly acts on the diffusion of molecules through the polymer. We have adapted and used the thermo-poro-metry technique in order to assess the crosslinking of PE. Using this investigation we have characterized the cross linking as a function of the dose, especially with respect to the mesh size distribution. We have also established a relationship allowing the determination of the crosslinking density in a swelled PE sample by p-xylene by DSC analysis. (author)

  11. Gamma radiolysis of water solutions relevant to the nuclear fuel waste management program

    International Nuclear Information System (INIS)

    The gamma radiolysis of water was investigated for conditions relevant to studies of the geological disposal of nuclear fuel waste. Chemical kinetic calculations were carried out for seven systems: argon-purged water; O2-purged water; N2O-purged water; O2-purged solution containing 0.01 mol/ell sodium formate; O2-purged solution containing 0.01 mol/ell t-butanol; N2O-purged solution containing 0.01 mol/ell Na2CO3; and argon-purged solution containing 0.169 mol/ell Cl- ions. The initial pH in all systems was set at 9.5. The concentration of the important oxidants and reductants, both molecular and radical species, are presented as a function of the dose rate and the radiolysis time. In almost all cases, radical species are at steady state after 20 h of irradiation. In argon-saturated solutions, concentrations of all radiolysis products are low (-8 mol/ell). In oxygen-saturated solutions containing formate, an H2O2 concentration as high as 1.7 x 10-3 mol/ell was calculated after 20 h of irradiation at a dose rate of 280 Gy/h

  12. Revaluation of hydrogen generation by water radiolysis in SDS vessels at TMI-2 accident

    International Nuclear Information System (INIS)

    Two years after Three Mile Island Unit 2 (TMI-2) loss-of-coolant accident, radioactive contaminated water has been processed by Submerged Demineralizer System (SDS) with two types of zeolite adsorbents to remove radioactive nuclides of Sr-90, Cs-134 and Cs-137. During and after the process, adsorption amount and distribution of nuclides on the zeolites, residual water content and thermal conductivity in the SDS vessels have been measured or estimated for verification of safety in the process, subsequent transportation and disposal. Hydrogen generation has been also evaluated mainly by direct monitoring in the large-scale of vessel after the process. In this work, the revaluation of hydrogen generation was demonstrated on the basis of the open information of vessel, and the latest experimental data obtained in adsorption and radiolysis occurring in small-scale of zeolite-water mixtures. As a property of the zeolites (UOP IE-96, A-51), adsorption and desorption of water vapour on the zeolites were observed as a function of relative pressure corresponding to relative humidity. 10-20 wt% of water was found to be physically and chemically adsorbed on the zeolites within normal humidity of 20 to 90 %RH, reflecting residual water content absorbed on the dominant zeolites in the dewatering of vessels after the process. Hydrogen generated in the radiolysis of zeolite-water mixtures was further measured to obtain the observed yields of hydrogen as functions of water content in the mixtures and of the height of mixtures. It was found that additional water radiolysis took place through the energy dissipation of radiation to the zeolites, and that liquid depth effect on the yield in water was depressed by adding zeolites to water. Based on these experimental results and further estimations, hydrogen generation dependent on decay heat and water content in the SDS vessel was finally revaluated. The procedure and results in this revaluation would be helpful for the decontamination

  13. Pulse radiolysis studies of liquid heavy water at temperatures up to 250 degrees C

    International Nuclear Information System (INIS)

    This report documents the rate constants and associated activation energies for the reactions of the primary radical species, eaq-, ·OD and ·D, which are formed during the radiolysis of heavy water within the temperature range 20 to 250 oC. These heavy-water data have been compared with the corresponding information for light water. These kinetic data form part of the database that is required to model the aqueous radiation chemistry that occurs within the core of the heavy water cooled and moderated CANDU reactor. (author)

  14. Study of water radiolysis in relation with the primary cooling circuit of pressurized water reactors

    International Nuclear Information System (INIS)

    This memorandum shows a fundamental study on the water radiolysis in relation with the cooling primary circuit of PWR type reactors. The water of the primary circuit contains boric acid a soluble neutronic poison and also hydrogen that has for role to inhibit the water decomposition under radiation effect. In the aim to better understand the mechanism of dissolved hydrogen action and to evaluate the impact of several parameters on this mechanism, aqueous solutions with boric acid and hydrogen have been irradiated in a experimental nuclear reactor, at 30, 100 and 200 Celsius degrees. It has been found that, with hydrogen, the water decomposition under irradiation is a threshold phenomenon in function of the ratio between the radiation flux '1' B(n, )'7 Li and the gamma flux. When this ratio become too high, the number of radicals is not sufficient to participate at the chain reaction, and then water is decomposed in O2 and H2O2 in a irreversible way. The temperature has a beneficial part on this mechanism. The iron ion and the copper ion favour the water decomposition. (N.C.)

  15. Hydrogen generation by water radiolysis with immersion of oxidation products of Zircaloy-4

    International Nuclear Information System (INIS)

    In order to predict the hydrogen gas generation from seawater or water in which debris would be included by the severe accident of nuclear power plant, we investigated the effect of ZrO2 and the oxidation products of Zircaloy-4 on hydrogen gas generation by radiolysis of water since the radiolytic generation could be affected by materials immersed in water. Powders of well-characterized oxides and oxidation products were immersed in either seawater or distilled water, and irradiated by gamma ray from a Co-60 source. The observed hydrogen yield, G(H2), was measured as a function of the weight fraction of oxide in water up to 50 wt%. The enhancement of the hydrogen generation by radiolysis of water with the commercial oxides and the oxidation products of Zircaloy-4 was quite small or absent in seawater. But the enhancement was observed in the presence of the oxides or the oxidation products at low weight fraction in distilled water. This enhancement in distilled water seemed to be dependent on specific surface area or particle size, but its dependence on the crystal structure was not apparent in the experimental results. The enhancement was saturated at higher ZrO2 weight fractions and it was not apparent in the seawater. (author)

  16. A pulse radiolysis study of oil/water microemulsions

    International Nuclear Information System (INIS)

    The spectrum and yield of eaq- in quaternary benzene/water and dodecane/water microemulsions were found to be identical with those in pure water. This indicates probably the scavenging of excess electrons produced in the oil by water. To the contrary, the yield of OH radicals, determined after scavenging and conversion into (SCN)2-·, was proportional to water content of the microemulsion. The eaq- decay and the total yield of peroxides in aerated microemulsion were determined and the characteristics of oxidation in microemulsion was discussed. (author)

  17. Rate constants and g-values for the simulation of the radiolysis of light water over the range 0-300 deg C

    International Nuclear Information System (INIS)

    This report collects together all the rate constants, pK's and g-values required for the simulation of the radiolysis of light water, at near-neutral pH, over the temperature range of room temperature to 300 deg C. As very few of the rate constants have been measured over this whole temperature range, the experimental data have been extrapolated using both the Arrhenius equation and the Noyes model. In general, each rate constant is given as a function of temperature using the Arrhenius equation. In some cases a polynomial function was used. The g-values for the radiolysis with low linear energy transfer radiation are given as linear functions of temperature. A preliminary estimate of the g-values for fast-neutron radiolysis at room temperature and at 300 deg C has been made, based on the results of the published ion-beam data and on unpublished high-temperature ion-beam studies at Chalk River Laboratories. (author). 91 refs., 14 tabs., 24 figs

  18. A Review of Radiolysis Concerns for Water Shielding in Fission Surface Power Applications

    Science.gov (United States)

    Schoenfeld, Michael P.

    2008-01-01

    This paper presents an overview of radiolysis concerns with regard to water shields for fission surface power. A review of the radiolysis process is presented and key parameters and trends are identified. From this understanding of the radiolytic decomposition of water, shield pressurization and corrosion are identified as the primary concerns. Existing experimental and modeling data addressing concerns are summarized. It was found that radiolysis of pure water in a closed volume results in minimal, if any net decomposition, and therefore reduces the potential for shield pressurization and corrosion. With the space program focus m emphasize more on permanent return to the Moon and eventually manned exploration of Mars, there has been a renewed look at fission power to meet the difficult technical & design challenges associated with this effort. This is due to the ability of fission power to provide a power rich environment that is insensitive to solar intensity and related aspects such as duration of night, dusty environments, and distance from the sun, etc. One critical aspect in the utilization of fission power for these applications of manned exploration is shielding. Although not typically considered for space applications, water shields have been identified as one potential option due to benefits in mass savings and reduced development cost and technical risk (Poston, 2006). However, the water shield option requires demonstration of its ability to meet key technical challenges including such things as adequate natural circulation for thermal management and capability for operational periods up to 8 years. Thermal management concerns have begun to be addressed and are not expected to be a problem (Pearson, 2007). One significant concern remaining is the ability to maintain the shield integrity through its operational lifetime. Shield integrity could be compromised through shield pressurization and corrosion resulting from the radiolytic decomposition of water.

  19. The behaviour of phenylphosphine oxide containing polyimides in a water plasma following γ-radiolysis

    International Nuclear Information System (INIS)

    The surface oxidation of two polyimides containing fluorinated phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied by (XPS) spectroscopy following γ-radiolysis under vacuum or in air and subsequent treatment in a water plasma. The changes in the O 1s/C 1s ratios obtained from (XPS) analysis showed that on exposure to the water plasma the ratio increases and then levels to a constant value which is similar to that found for exposure to the plasma without prior γ-radiation treatment. Evidence for the formation of phosphate species was also obtained from the (XPS) analyses

  20. Kinetic behaviors of e{sub a}q- and ·OH radical in water radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Kim, A Yeong; Kim, Han-Chul [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Lee, Jun-Yeop; Yun, Jong-Il [KAIST, Daejeon (Korea, Republic of)

    2015-05-15

    Iodine in the aqueous solution changes its volatile molecule through chemical complexation with free radicals which are formed in water radiolysis. In particular, aqueous electrons (e{sub a}q-) and hydroxyl radicals (·OH) play an essential role in iodine behavior. Aqueous electrons react with oxygen and thus produce ·O{sub 2}- radical which is a strong reductant of molecular iodine. On the other hand, the rate of iodide oxidation depends on the concentration of ·OH that oxidize I- to·I which eventually combines to form I{sub 2} (volatile species). Korea Institute of Nuclear Safety (KINS) has been developing the Radio-Active Iodine chemistry Model (RAIM) which simulates iodine behavior in the containment. However, it does not reflect the water radiolysis reaction in detail that has been just applied based on the IMOD (Iodine Model for containment codes) methodology. This paper presents the methods to compute the concentration of water radiolysis products and suggests the application of computing methods by comprehending the behavior of e{sub a}q- and ·OH. The calculation code to compute the concentration of water radiolysis products has been developed and validated. Based on the code, the reaction kinetics of aqueous electrons and hydroxyl radicals was investigated. The calculation code developed in the present work can be applied to RAIM for the simplified calculation of water radiolysis products.

  1. Aspects of the physics and chemistry of water radiolysis by fast neutrons and fast electrons in nuclear reactors

    International Nuclear Information System (INIS)

    Detailed radiation physics calculations of energy deposition have been done for the coolant of CANDU reactors and Pressurized Water Reactors (PWRs). The geometry of the CANDU fuel channel was modelled in detail. Fluxes and energy-deposition rates for neutrons, recoil ions, photons, and fast electrons have been calculated using MCNP4B, WIMS-AECL, and specifically derived energy-transfer factors. These factors generate the energy/flux spectra of recoil ions from fast-neutron energy/flux spectra. The energy spectrum was divided into 89 discrete ranges (energy bins). The production of oxidizing species and net coolant radiolysis can be suppressed by the addition of hydrogen to the coolant of nuclear reactors. It is argued that the net dissociation of coolant by gamma rays is suppressed by lower levels of excess hydrogen than when dissociation is by ion recoils. This has consequences for the modelling of coolant radiolysis by homogeneous kinetics. More added hydrogen is required to stop water radiolysis by recoil ions acting alone than if recoil ions and gamma rays acted concurrently in space and time. Homogeneous kinetic models and experimental data suggest that track overlap is very inefficient in providing radicals from gamma-ray tracks to recombine molecular products in ion-recoil tracks. An inhomogeneous chemical model is needed that incorporates ionizing-particle track structure and track overlap. Such a model does not yet exist, but a number of limiting cases using homogeneous kinetics are discussed. There are sufficient uncertainties and contradictions in the data relevant to the radiolysis of reactor coolant that the relatively high CHC's (critical hydrogen concentration) observed in NRU reactor experiments (compared to model predictions) may be explainable by errors in fundamental data and understanding of water radiolysis under reactor conditions. The radiation chemistry program at CRL has been focused to generate quantitative water-radiolysis data in a

  2. The temperature dependence of the rate constants and yields for the simulation of the radiolysis of heavy water

    International Nuclear Information System (INIS)

    At Chalk River Laboratories, a computer code is being developed to model the radiolysis of the heavy water in the moderator and the heat-transport system in CANDU reactors. This report collects together, for heavy water, the current knowledge regarding the rate constants, pKa's, yields and diffusion coefficients based on measurements in this laboratory and reports in the literature. The latest data available for the radiolysis of light water are generally included for comparison, which forms a partial update to the report on the radiolysis of light water (Elliot, AECL- 11073, COG-94-167, 1994). There are some reactions where little or no data are available at ambient or elevated temperatures; in these cases, an indication is given of the approach that will be taken to measure or estimate the required parameters. (author)

  3. Modelling of hydrogen production from pore water radiolysis in cemented intermediate level waste

    OpenAIRE

    Di Giandomenico M.-V.; Foct F.; Bouniol P.

    2013-01-01

    In France, some of the intermediate and low level wastes are embedded in hydraulic binder and put into concrete canisters. They contain β and γ emitters which cause an irradiation of water present in the pores of the hydraulic binder. This is responsible for a dihydrogen (H2) production due to radiolysis. EDF R&D and CEA have collaborated since many years in order to understand this phenomenon and develop a model called DO-RE-MI which can predict such a production of dihydrogen in concrete wa...

  4. O2 and glutathione effects on water radiolysis: a simulation study

    International Nuclear Information System (INIS)

    We present a MC simulation of water radiolysis when O2 and glutathione are present in the solution. Our simulation is based on the continuum approximation proposed by Green and co-workers'. We investigate in particular the sensitivity of the yield of HO2.+O2-. to the concentration of O2 and glutathione and to the LET of the ionising radiation. We demonstrate that the production of HO2./O2-. is highly sensitive to these parameters and that the variation of their yield with the O2 concentration shares remarkable similarities with the O2 effect reported for biological cell damage efficiency .

  5. A quantitative model of water radiolysis and chemical production rates near radionuclide-containing solids

    Science.gov (United States)

    Dzaugis, Mary E.; Spivack, Arthur J.; D'Hondt, Steven

    2015-10-01

    We present a mathematical model that quantifies the rate of water radiolysis near radionuclide-containing solids. Our model incorporates the radioactivity of the solid along with the energies and attenuation properties for alpha (α), beta (β), and gamma (γ) radiation to calculate volume normalized dose rate profiles. In the model, these dose rate profiles are then used to calculate radiolytic hydrogen (H2) and hydrogen peroxide (H2O2) production rates as a function of distance from the solid-water interface. It expands on previous water radiolysis models by incorporating planar or cylindrical solid-water interfaces and by explicitly including γ radiation in dose rate calculations. To illustrate our model's utility, we quantify radiolytic H2 and H2O2 production rates surrounding spent nuclear fuel under different conditions (at 20 years and 1000 years of storage, as well as before and after barrier failure). These examples demonstrate the extent to which α, β and γ radiation contributes to total absorbed dose rate and radiolytic production rates. The different cases also illustrate how H2 and H2O2 yields depend on initial composition, shielding and age of the solid. In this way, the examples demonstrate the importance of including all three types of radiation in a general model of total radiolytic production rates.

  6. pH dependence of H{sub 2}O{sub 2} in the radiolysis of water

    Energy Technology Data Exchange (ETDEWEB)

    LaVerne, J.A.; Roth, O. [Univ. of Notre Dame, Notre Dame, Indiana (United States); Pimblott, S.M. [Univ. of Manchester, Manchester (United Kingdom)

    2010-07-01

    The yields of hydrogen peroxide have been experimentally determined in the gamma and heavy ion radiolysis of aerated water at a pH range of 1-14. Experimental results have been combined with diffusion-kinetic track models to obtain a complete mechanistic understanding of the production of hydrogen peroxide over the pH range examined in this work. Hydrogen peroxide yields from the radiolysis of aerate water increase at both high and low pH values as compared to normal water. The production of hydrogen peroxide is found to mainly be due to relatively long time reactions of the hydroperoxyl radical and its conjugate base in the homogeneous radiolysis regime. (author)

  7. State of knowledge on the water radiolysis in cemented wasteforms and its approach by simulation

    International Nuclear Information System (INIS)

    The decomposition of water under radiation within the cementitious matrix is at the origin of a potential source of harmful effects in the wasteform and their environment (pressurization and emanation of di-hydrogen) which can have an impact on the safety. In the aim of a better evaluation of the 'H2' risk induced by such a complex and heterogeneous system, this document is an analysis of the elements necessary for a global understanding of the radiolysis in the cemented wasteform to be achieved: - summary of the basic knowledge on water radiolysis with transposition to the cementitious medium, - critical review of the various phenomenologies at work in a wasteform (radioactive source-term, gas transport, mineral equilibria); description of their mutual couplings and of their feedback on radiolytic chemistry; identification of the determining parameters, - presentation of a selection of experimental facts putting in light some theoretical points, - presentation of an outline of operational model deriving from the global vision; presentation of an adapted tool for simulation (CHEMSIMUL) and study of the influence of the principal parameters, starting from a reference case. The main result of this work is that it is shown, in the case of a βγ source term, that the control of the pore fluid composition by calcium octo-hydrate peroxide constitutes an efficient regulating mechanism for the radiolysis and H2 production. Not likely possible in the case of an α source term, this suggests a separate management of the wasteform according to their radiological contents. The gaps and limits of the model which are also evoked are promising of a lot of research prospects, primarily of a fundamental nature (impact of the porous medium). (author)

  8. Water radiolysis effect on IASCC growth behavior in BWR water conditions in highly irradiated austenitic stainless steel

    International Nuclear Information System (INIS)

    For study of water radiolysis effect caused by gamma-rays from radioactive material on irradiation-assisted stress corrosion cracking (IASCC) growth behavior, crack growth tests in highly irradiated austenitic stainless steel are performed in simulated BWR water conditions (at ∼563 K). The compact tension (CT) specimens made of 316L stainless steels are irradiated with neutrons up to ∼12 dpa in the Japan Materials Testing Reactor (JMTR). Post-irradiation annealing (PIA) at 973 K for 1 hour is applied to one of the specimens, which shows the recovery of material properties corresponding to the unirradiated ones but the radioactivity of highly irradiated material as it is. The gamma-ray absorbed dose rate in water is calculated near the crack tip of the CT specimen, and the stable concentrations of H2O2, O2 and H2 in water near the crack tip are estimated by radiolysis calculation for some feed water conditions of normal water chemistry (NWC), deaerated water and hydrogen water chemistry (HWC). The preliminary results of the crack growth rate (CGR) for the highly irradiated specimens and the annealed specimen are presented, and the relationship between the CGRs and the water chemistry such as the concentrations of radiolytic species and the electrochemical corrosion potential (ECP) is discussed. (author)

  9. Effect of water alpha radiolysis on the spent nuclear fuel UO2 matrix alteration

    International Nuclear Information System (INIS)

    Leaching experiments with solution renewal were carried out on UO2 pellets doped with alpha emitters (238/239Pu) to quantify the impact of alpha irradiation on UO2 matrix alteration. Three batches of doped UO2 pellets with different alpha flux levels were studied as well as spent fuel fragments. Interim storage in air of UO2 pellets doped with alpha emitters results in variations of the UO2 surface reactivity, which depends on the alpha particle flux at the interface and on the interim storage duration. The variation in the surface reactivity and the greater uranium release following interim storage cannot be attributed to the effect of alpha radiolysis in aerated media since the uranium release tends toward the same value after several leaching cycles for the doped UO2 pellet batches and spent fuel. However, leaching experiments performed in deaerated media after annealing the samples and pre-leaching the surface suggest that alpha radiolysis does indeed affect the dissolution, which varies with the flux at the UO2/water interface. (authors)

  10. A quantitative model of water radiolysis and chemical production rates near radionuclide-containing solids

    International Nuclear Information System (INIS)

    We present a mathematical model that quantifies the rate of water radiolysis near radionuclide-containing solids. Our model incorporates the radioactivity of the solid along with the energies and attenuation properties for alpha (α), beta (β), and gamma (γ) radiation to calculate volume normalized dose rate profiles. In the model, these dose rate profiles are then used to calculate radiolytic hydrogen (H2) and hydrogen peroxide (H2O2) production rates as a function of distance from the solid–water interface. It expands on previous water radiolysis models by incorporating planar or cylindrical solid–water interfaces and by explicitly including γ radiation in dose rate calculations. To illustrate our model's utility, we quantify radiolytic H2 and H2O2 production rates surrounding spent nuclear fuel under different conditions (at 20 years and 1000 years of storage, as well as before and after barrier failure). These examples demonstrate the extent to which α, β and γ radiation contributes to total absorbed dose rate and radiolytic production rates. The different cases also illustrate how H2 and H2O2 yields depend on initial composition, shielding and age of the solid. In this way, the examples demonstrate the importance of including all three types of radiation in a general model of total radiolytic production rates. - Highlights: • Our model quantifies radiolytic chemical production near solid–water interfaces. • The model accounts for chemical production by α, β and γ radiation. • The model is applicable to both planar and curved surfaces. • Relative production by α, β and γ radiation strongly depends on solid composition. • We apply the model to young and old spent nuclear fuel, with and without cladding

  11. Correlation between yields of positronium and hydrogen, excited molecules, hydrated electron appearing during water radiolysis

    International Nuclear Information System (INIS)

    Analytic expression for dependences of the yields of positronium (Ps) and radiolytic hydrogen (H2) on concentration of dissolved in water substances (acetone, H2O2, inorganic acids, salts of various metals) under 60Coγ-irradiation were obtained on the basis of assumptions about similarity of the mechanism of Ps and H2 formation - intratrack recombination with participation of nonhydrated electron. Found equations were used for analyzing large amount of experimental results. In majority of cases the dissolved substances effect alike on Ps and H2 yields. Some exceptions are explained in the framework of considered model. It was established that nonhydrated electron represents the direct precursor of not only Ps and radiolytic hydrogen but solvated electron and excited molecules appearing during radiolysis of water and organoaqueous solutions

  12. Product yields in water radiolysis with heavy ions relevant to track structures

    International Nuclear Information System (INIS)

    Radiolysis of neutral water with high-energy heavy ions has been investigated since FY 2002. It has been purposed to clarify track structure and its dynamics. Until the end of FY 2007, following 3 things has been accomplished. (A) primary yields, which are defined as yields approximately at 100 ns after radiation passage, of main products have widely been determined, (B) Temporal behavior of water decomposition radicals during ns-μs has been investigated, and (C) a sensitive method to determine Hydroxyl radical OH yield has also been developed and applied to heavy ion irradiations. In FY 2008, (A) and (C) are extended to higher linear energy transfer (LET) regions by using energy absorber at the upstream or by taking heavier ions, Kr and Xe. In addition, (C) was also applied in (D) challenge to scrutinize Hydroxyl radical OH yield near and at the Bragg peak. (author)

  13. The impact of water radiolysis on the ECP in PWR primary coolant circuits

    International Nuclear Information System (INIS)

    A chemistry/radiolysis/mixed potential model has been developed to calculate radiolytic species concentrations and corrosion potential at closely spaced points around the primary coolant circuit of a pressurized water reactor (PWR). The pH, as a function of temperature of the coolant, is calculated at each point of the primary loop using a chemical equilibrium model. The radiolysis model is a modified version of the code developed to previously model the radiochemistry and corrosion properties of Boiling Water Reactor (BWR) primary coolant circuits by Macdonald. The modifications include additional species and reactions taken from other models for describing the radiolysis of water. The model offers the possibility of choosing up to 48 different sets of reactions when calculating species concentrations. The set of 34 reactions used to calculate the ECP in a BWR by Macdonald was completed up to 48 reactions. Six different modified subsets were obtained from that original set as indicated. In this paper, we explore (1) the impact of choosing different sets in the calculation of the ECP and (2) the impact on the ECP calculations when 14 additional authors' data for the 48 reactions were used (in addition to the original 34 reaction sets used by Macdonald and the set of 48 reactions obtained by adding 14 additional reactions to the original 34 reactions set; data on the 48 reactions from the 14 authors was compiled and shown in Table 4. The radiolytic yields for the primary species (14 different species as this paper we selected to work with the set shown in Table 2. It is important to recognize the dictions due to the fact that we currently have electrochemical kinetic data for only a limited number of redox species (H2, O2, H2O2) on Type 304 SS, so only this substrate could be modeled with respect to the ECP. However, it is believed that Type 304 SS serves as a good analog for other stainless steels and, perhaps, for nickel-based alloys, such as Alloys 600 and 718

  14. Radiolysis of kaempferol in water/methanol mixtures. Evaluation of antioxidant activity of kaempferol and products formed.

    Science.gov (United States)

    Marfak, Abdelghafour; Trouillas, Patrick; Allais, Daovy-Paulette; Champavier, Yves; Calliste, Claude-Alain; Duroux, Jean-Luc

    2003-02-26

    Oxidative reaction between hydroxymethyl radical ((*)CH(2)OH) and kaempferol, in methanol and methanol/water mixtures, was studied by gamma-radiolysis using a (60)Co source. Radiolysis was performed with concentrations and doses ranging from 5 x 10(-)(5) M to 5 x 10(-)(3) M and from 0.5 kGy to 14 kGy, respectively. Kaempferol degradation was followed by HPLC. Results showed that (*)CH(2)OH reacts with kaempferol at the 3-OH group and produces two depsides (K1 and K2) and other products including K3. K1, K2, and K3 were identified by NMR, LC-MS, and HRMS. The kaempferol degradation pathway leading to the K1, K2, and K3 formation is proposed. It was observed that the more water concentration in the irradiation medium increases, the more K2 concentration increases. Comprehension of food preservation is not clear because many phenomena occurring during irradiation are not established. Radiolysis of kaempferol in water/methanol mixtures helps to elucidate the phenomenon and it is possible that during the treatment of nutriments by gamma-irradiation, a series of products such as depside K2 could be formed. Antioxidant properties of kaempferol radiolysis products were evaluated according to their capacity to decrease the EPR DPPH (1,1-diphenyl-2-picrylhydrazil) signal and to inhibit superoxide radicals formed by the enzyme reaction "xanthine + xanthine oxidase". PMID:12590467

  15. Modelling of hydrogen production from pore water radiolysis in cemented intermediate level waste

    Directory of Open Access Journals (Sweden)

    Di Giandomenico M.-V.

    2013-07-01

    Full Text Available In France, some of the intermediate and low level wastes are embedded in hydraulic binder and put into concrete canisters. They contain β and γ emitters which cause an irradiation of water present in the pores of the hydraulic binder. This is responsible for a dihydrogen (H2 production due to radiolysis. EDF R&D and CEA have collaborated since many years in order to understand this phenomenon and develop a model called DO-RE-MI which can predict such a production of dihydrogen in concrete waste packages. A parametric study, using the developed model, was implemented in order to determine the effects of each parameter on H2 production. The main results are presented in this paper.

  16. Interaction study of water radiolysis products with Crotalus durissus terrificus miotoxin

    International Nuclear Information System (INIS)

    Ionizing radiation has been satisfactorily employed for venoms detoxification. In this report, the radiation was employed to verify the effects caused by the radiolysis products of water on the Crotamine, toxin purified from Crotalus durissus terrificus venom. These effects were analyzed using some substances called 'scavengers', those substances competes for specific reactive species hindering them to act on the toxins molecules. In order to study the possible structural damages caused on the toxins, circular dichroism, fluorescence, nuclear magnetic resonance, amino acids analysis and intravital microscopy were employed. Our results indicate that ionizing radiation caused structure alterations, mainly, in secondary and tertiary structure of crotamine. In the irradiated crotamine, was not possible to determine tridimensional structure. And the crotamine toxic effect was removed by ionizing radiation. (author)

  17. Modelling of hydrogen production from pore water radiolysis in cemented intermediate level waste

    International Nuclear Information System (INIS)

    In France, some of the intermediate and low level wastes are embedded in hydraulic binder and put into concrete canisters. They contain β and γ emitters which cause an irradiation of water present in the pores of the hydraulic binder. This is responsible for a dihydrogen (H2) production due to radiolysis. EDF R and D and CEA have collaborated since many years in order to understand this phenomenon and develop a model called DO-RE-MI which can predict such a production of dihydrogen in concrete waste packages. A parametric study, using the developed model, was implemented in order to determine the effects of each parameter on H2 production. The main results are presented in this paper. (authors)

  18. Production of a fluorescence probe in ion-beam radiolysis of aqueous coumarin-3-carboxylic acid solution-2: Effects of nuclear fragmentation and its simulation with PHITS

    Energy Technology Data Exchange (ETDEWEB)

    Maeyama, Takuya [Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Yamashita, Shinichi; Taguchi, Mitsumasa [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma 370-1292 (Japan); Baldacchino, Gerard [CEA Saclay, IRAMIS, UMR 3299 CEA-CNRS SIS2M, Laboratoire de Radiolyse, F-91191 Gif sur Yvette Cedex (France); Sihver, Lembit [Department of Physics, University of Houston, Houston, TX 77204-5005 (United States); Department of Nuclear Engineering, Texas A and M University, TX 77843-3133 (United States); Department of Roanoke College, Salem, VA 24153 (United States); Department of Nuclear Engineering, Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Murakami, Takeshi [Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Katsumura, Yosuke, E-mail: katsu@n.t.u-tokyo.ac.jp [Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nuclear Professional School, School of Engineering, University of Tokyo, 2-22 Shirakata-shirane, Tokai-mura, Naka-gun, Ibaraki 319-1188 (Japan)

    2011-12-15

    The G(OH) values in aqueous coumarin-3-carboxylic-acid (3-CCA) solutions irradiated with {sup 12}C{sup 6+} beams having the energies of 135, 290 and 400 MeV/u were measured by a fluorescent method around the Bragg peak, with 0.6 mm intervals, and quartz cells of 1 cm optical lengths, at the Heavy Ion Medical Accelerator in Chiba, National Institute of Radiological Sciences (NIRS). For each ion, the G(OH) has been calculated as a function of dose average LET and position. The calculated results have been compared to measurements, and the results, reproducibility and reliability of the calculations are discussed in the paper. - Highlights: > Therapeutic ion beam has energy of several hundred MeV/u because it is necessary for a few tens cm range. > With such high energy, nuclear fragmentations of carbon ions occur resulting in production of lighter ions. > In this study, OH yield in water radiolysis near the Bragg peak of therapeutic ion beams was measured. > Measured yields are discussed considering nuclear fragmentation by PHITS code.

  19. LC-MS analysis in the e-beam and gamma radiolysis of metoprolol tartrate in aqueous solution: Structure elucidation and formation mechanism of radiolytic products

    Energy Technology Data Exchange (ETDEWEB)

    Slegers, Catherine [Unite d' Analyse Chimique et Physico-chimique des Medicaments, Universite Catholique de Louvain, CHAM 72.30, Avenue E. Mounier, 72, B-1200, Brussels (Belgium)]. E-mail: catherine.slegers@skynet.be; Maquille, Aubert [Unite d' Analyse Chimique et Physico-chimique des Medicaments, Universite Catholique de Louvain, CHAM 72.30, Avenue E. Mounier, 72, B-1200, Brussels (Belgium); Deridder, Veronique [Unite d' Analyse Chimique et Physico-chimique des Medicaments, Universite Catholique de Louvain, CHAM 72.30, Avenue E. Mounier, 72, B-1200, Brussels (Belgium); Sonveaux, Etienne [Unite de Chimie Pharmaceutique et de Radiopharmacie, Universite Catholique de Louvain, Brussels (Belgium); Habib Jiwan, Jean-Louis [Laboratoire de Spectrometrie de Masse, Universite Catholique de Louvain, Louvain-La-Neuve (Belgium); Tilquin, Bernard [Unite d' Analyse Chimique et Physico-chimique des Medicaments, Universite Catholique de Louvain, CHAM 72.30, Avenue E. Mounier, 72, B-1200, Brussels (Belgium)

    2006-09-15

    E-beam and gamma products from the radiolysis of aqueous solutions of ({+-})-metoprolol tartrate, saturated in nitrogen, are analyzed by HPLC with on-line mass and UV detectors. The structures of 10 radiolytic products common to e-beam and gamma irradiations are elucidated by comparing their fragmentation pattern to that of ({+-})-metoprolol. Two of the radiolytic products are also metabolites. Different routes for the formation of the radiolytic products are proposed.

  20. LC MS analysis in the e-beam and gamma radiolysis of metoprolol tartrate in aqueous solution: Structure elucidation and formation mechanism of radiolytic products

    Science.gov (United States)

    Slegers, Catherine; Maquille, Aubert; Deridder, Véronique; Sonveaux, Etienne; Habib Jiwan, Jean-Louis; Tilquin, Bernard

    2006-09-01

    E-beam and gamma products from the radiolysis of aqueous solutions of (±)-metoprolol tartrate, saturated in nitrogen, are analyzed by HPLC with on-line mass and UV detectors. The structures of 10 radiolytic products common to e-beam and gamma irradiations are elucidated by comparing their fragmentation pattern to that of (±)-metoprolol. Two of the radiolytic products are also metabolites. Different routes for the formation of the radiolytic products are proposed.

  1. LC-MS analysis in the e-beam and gamma radiolysis of metoprolol tartrate in aqueous solution: Structure elucidation and formation mechanism of radiolytic products

    International Nuclear Information System (INIS)

    E-beam and gamma products from the radiolysis of aqueous solutions of (±)-metoprolol tartrate, saturated in nitrogen, are analyzed by HPLC with on-line mass and UV detectors. The structures of 10 radiolytic products common to e-beam and gamma irradiations are elucidated by comparing their fragmentation pattern to that of (±)-metoprolol. Two of the radiolytic products are also metabolites. Different routes for the formation of the radiolytic products are proposed

  2. A model for radiation energy deposition in natural uranium-bearing systems and its consequences to water radiolysis

    International Nuclear Information System (INIS)

    Water radiolysis is of great concern in the concept of final disposal of nuclear waste in geological formations. In this paper, a model is developed for radiation energy deposition and its consequences to water radiolysis. The model concepts are based on radiation energy deposition in the porewater and other constituents of a uranium ore (the Cigar Lake uranium deposit). Radiation is randomly generated within grains of uranium minerals in the ore, by the Monte Carlo method. The radiation energy is then allowed to deposit into the various constituents of the ore. The fraction of the total radiation energy absorbed by water is obtained, and the oxidant production rate is calculated with G-values of water. When back-reactions of the oxidants and reductants projected by other researchers in similar systems are accounted for, the calculated oxidant production rate is in agreement with that predicted by mass transport models. (orig.)

  3. Effects of radiolysis of humid air and water on the corrosion of the oxide layer of the oxidized Zircaloy 4

    International Nuclear Information System (INIS)

    As compacted waste parcels notably contain components in oxidized Zircaloy-4 which contain traces of activation products, fission products and actinides in the surface layer, as deep geological storage of such wastes may result in the release of radio-elements due to water-induced corrosion, and as water irradiation results in water radiolysis which may accelerate the corrosion process, this research thesis aims at understanding the alteration mechanisms of oxidized Zircaloy-4 when in contact with humid air an liquid water submitted to ionizing radiation. More precisely, the author studied the impact of radiolysis which is induced by proton and gamma radiations. Different gaseous atmospheres and aqueous media are used. Two different behaviours are identified leading to the formation of different compounds

  4. Water radiolysis in exchanged-montmorillonites: The H2 production mechanisms

    International Nuclear Information System (INIS)

    The radiolysis of water confined in montmorillonites is studied as a function of the composition of the montmorillonite, the nature of the exchangeable cation, and the relative humidity by following the H2 production under electron irradiation. It is shown that the main factor influencing this H2 production is the water amount in the interlayer space. The effect of the exchangeable cation is linked to its hydration enthalpy. When the water amount is high enough to get a basal distance higher than 1.3 nm, then a total energy transfer from the montmorillonite sheets to the interlayer space occurs, and the H2 production measured is very similar to the one obtained in bulk water. For a basal distance smaller than 1.3 nm, the H2 production increases with the relative humidity and thus with the water amount. Lastly, electron paramagnetic resonance measurements evidence the formation of a new defect induced by ionizing radiation. It consists of a hydrogen radical (H2 precursor) trapped in the structure. This implies that structural hydroxyl bonds can be broken under irradiation, potentially accounting for the observed H2 production. (authors)

  5. Temperature effect on yield of molecular hydrogen at ν-radiolysis of liquid water

    International Nuclear Information System (INIS)

    The yield of molecular hydrogen has been measured during ν-radiolysis of air-saturated water and aqueous solutions of KBr, NO3, NaCl in 30-250 deg C range. The initial yield of molecular hydrogen in pure water does not depend on temperature in 20-250 deg C range and equals 0.44+-0.02 molecules per 100 eV. In saturated sodium chloride solutions Gsub(Hsub(2)) increases from 0.51+-0.03 at 20 deg up to 0.79+-0.07 molecules per 100 eV at 250 deg. In 1 mol/l NaNO3 solution Gsub(Hsub(2))=0.11 molecules per 100 eV at 20 deg increases with the growth of temperature reaching the value of 0.29 molecules per 100 eV in 150-2O0 deg range and then it falls down to 0.13 molecules per 100 eV at 250 deg. The obtained results are discussed within the framework of recombination - diffusion model of water radyolysis

  6. Radical cations of some water-soluble organoselenium compounds: Insights from pulse radiolysis studies

    Energy Technology Data Exchange (ETDEWEB)

    Priyadarsini, K. Indira [Radiation and Photochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India)], E-mail: kindira@barc.gov.in; Mishra, B. [Radiation and Photochemistry Division, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India)

    2008-10-15

    Radical cations of three water-soluble organoselenium compounds, viz., selenourea, selenomethionine, and selenocystine, were produced and their reactions in the pH range 1-7 were studied using nanosecond pulse radiolysis technique. The radical cations, centered on the selenium atom, were generated by one-electron oxidation using hydroxyl ({sup {center_dot}}OH) radicals and Cl{sub 2}{sup {center_dot}}{sup -} and Br{sub 2}{sup {center_dot}}{sup -} radicals. The radical cations of selenourea were converted to dimer radical cations in the entire pH range, which in presence of oxygen released elemental selenium as one of the products. The monomer radical cations of selenomethionine are stabilized at neutral pH by the lone pair of electrons on the N atom of the amino group and undergo partial decarboxylation to produce {alpha}-amino selenyl radicals, which are reducing in nature. At highly acidic conditions, when the lone pair is not available due to protonation, they were converted to dimer radical cations. Selenocystine, being a diselenide, produced monomer radical cations on one-electron oxidation in the entire pH range and acquires stability by sharing the electrons between the two adjacent selenium atoms.

  7. Simulation of the radiolysis of water using Green's functions of the diffusion equation

    International Nuclear Information System (INIS)

    Radiation chemistry is of fundamental importance in the understanding of the effects of ionising radiation, notably with regard to DNA damage by indirect effect (e.g. damage by .OH radicals created by the radiolysis of water). In the recent years, Green's functions of the diffusion equation (GFDEs) have been used extensively in biochemistry, notably to simulate biochemical networks in time and space. In the present work, an approach based on the GFDE will be used to refine existing models on the indirect effect of ionising radiation on DNA. As a starting point, the code RITRACKS (relativistic ion tracks) will be used to simulate the radiation track structure and calculate the position of all radiolytic species formed during irradiation. The chemical reactions between these radiolytic species and with DNA will be done by using an efficient Monte Carlo sampling algorithm for the GFDE of reversible reactions with an intermediate state that has been developed recently. These simulations should help the understanding of the contribution of the indirect effect in the formation of DNA damage, particularly with regards to the formation of double-strand breaks. (authors)

  8. Low LET radiolysis escape yields for reducing radicals and H2 in pressurized high temperature water

    Science.gov (United States)

    Sterniczuk, Marcin; Yakabuskie, Pamela A.; Wren, J. Clara; Jacob, Jasmine A.; Bartels, David M.

    2016-04-01

    Low Linear Energy Transfer (LET) radiolysis escape yields (G values) are reported for the sum (G(radH)+G(e-)aq) and for G(H2) in subcritical water up to 350 °C. The scavenger system 1-10 mM acetate/0.001 M hydroxide/0.00048 M N2O was used with simultaneous mass spectroscopic detection of H2 and N2 product. Temperature-dependent measurements were carried out with 2.5 MeV electrons from a van de Graaff accelerator, while room temperature calibration measurements were done with a 60Co gamma source. The concentrations and dose range were carefully chosen so that initial spur chemistry is not perturbed and the N2 product yield corresponds to those reducing radicals that escape recombination in pure water. In comparison with a recent review recommendation of Elliot and Bartels (AECL report 153-127160-450-001, 2009), the measured reducing radical yield is seven percent smaller at room temperature but in fairly good agreement above 150 °C. The H2 escape yield is in good agreement throughout the temperature range with several previous studies that used much larger radical scavenging rates. Previous analysis of earlier high temperature measurements of Gesc(radOH) is shown to be flawed, although the actual G values may be nearly correct. The methodology used in the present report greatly reduces the range of possible error and puts the high temperature escape yields for low-LET radiation on a much firmer quantitative foundation than was previously available.

  9. Radiolysis of water at elevated temperatures. Pt. 2: Irradiation with γ-rays and fast neutrons up to 2500C

    International Nuclear Information System (INIS)

    Determination of G-values of water decomposition products in neutral water formed by irradiation with γ-rays and fast neutrons at elevated temperatures up to 250oC was carried out by a combination of the NaNO2, acetone + methanol, and HClO4 + methanol solutions, which had been established at room temperature. By using a mass balance relation, the value for water decomposition, G-H20, was calculated. The yields of H2O2, formaldehyde and ethyleneglycol produced as a function of dose in the NaNO2 and HClO4 + methanol solutions were chosen to derive the GOH and GH202 by fitting the simulated calculation to the experimental results. In the γ-radiolysis, the G-values obtained in the present experiment are in good agreement with recently reported ones except for the GOH and GH202. The Gequ- for γ-radiolysis is in a good agreement with the reported values up to 200oC, but slightly lower at 250oC. The water decomposition gives a similar pattern with Geaq- yields. The GOH does not change significantly with temperature, which is contrary to the evaluation by other groups and the GH202 tends to increase with temperature. (author)

  10. Radiolysis of concrete

    International Nuclear Information System (INIS)

    A computer based radiation chemical program has been used to simulate experiments with gamma and alpha radiolysis in concrete. The experiments have been performed at Savannah River by Ned Bibler and co-workers. The calculations showed that the gas yields were very sensitive to the pH of the water phase. At a pH of 12.3 fairly good agreement was obtained between measured and calculated gas yields, assuming that the gas production only took place in the free water phase of the concrete. The following main conclusions could be made from both measurements and calculations: 1/ A steady state is obtained by gamma radiolysis of a NO3 free concrete. 2/ The yields are higher and a steady state is not obtained if NO3 is present. The yields are higher and a steady state is not obtained by alpha radiolysis. Calculations were also carried out on radiolysis from cladding hull waste stored in a cement matrix assuming both alpha and beta radiation. In the presence of an aerated gas phase a steady state pressure of more than 0.21 MPa was obtained.(author)

  11. Study of the effect of water radiolysis on zirconolite dissolution; Etude de l'effet de la radiolyse de l'eau sur la livixation de la zirconolite

    Energy Technology Data Exchange (ETDEWEB)

    Tribet, M

    2007-09-15

    Zirconolite is one of the matrices foreseen for the confinement of minor actinides in case of deep geological disposal. Indeed, zirconolite (general formula: CaZr{sub x}Ti{sub 3-x}O{sub 7} (0.8 {<=} x {<=} 1.37)) is able to incorporate rare earth elements and actinides by substitution in calcium and zirconium sites and, moreover, its chemical durability into water is well known. However, in case of deep geological disposal, after a long period, water can reach the confinement matrix and can be radiolysed at the moment of the radionuclide alpha decays. In this work we have thus studied the effects of water radiolysis induced by charged particles (alphas or protons) on the dissolution of a synthetic sintered zirconolite. The formula of this zirconolite is Ca{sub 0,8}Nd{sub 0,2}ZrTi{sub 1,8}Al{sub 0,2}O{sub 7} where Nd simulates the presence of trivalent and tetravalent actinides. We performed the irradiations with external ion beams in two distinct geometries where the fluences ranged from 10{sup 15} to 10{sup 16} ions.cm{sup -2}. In the first geometry the beam stops into water before the surface/water interface. In the second one the beam gets through the sample before stopping at the surface/water interface. The use of these different configurations allows to study the respective influence of parameters such as sample irradiation, Linear Energy Transfer at the surface/water interface or total deposited energy. The irradiations were performed on both crystalline and amorphous zirconolites in pure water or with complexing species such as F{sup -}. The sample dissolution has been monitored through the release of cations. The radiolytic production of H{sub 2}O{sub 2} has also been measured. Our results show that the water radiolysis has an effect on the preferential release of Zr, Ti and Nd: for these elements, releases are one or two order of magnitude higher than releases out of radiolysis. Such preferential releases occur whatever the temperature (20 or 50 C), the

  12. Radiolysis of medicinal herbs

    International Nuclear Information System (INIS)

    Radiolysis of the chief component of 124 types of medicinal herbs has been studied, with the majority stable under gamma irradiation with absorbed dose up to 10 kGy. 16 types of the herbs (12.9%) show radiolytic decomposition at 10 kGy, and 6 types (4.8%) at 5 kGy. No radiolytic decomposition is found at less than 2 kGy. The model system study showed that gamma radiolysis is different from thermohydrolytisis and photolysis and water absorbed on the herbs evidently affects the radiolytic decomposition of the herbs. Pulse and gamma radiolysis of baicalin, 1,8-dihydroxyanthraquinone-β-D-glucoside, glycyrrhizin and corydalis-B showed that some new compounds were formed due to OH radical attack. Fructose and glucose can inhibit the gamma radiolytic decomposition of herbs. Chemical clearance displays fruitful and hopeful prospect to disinfect herbs by gamma ray, with the following measures: 1. keeping the herbs in dry state, 2. making bolus by mixing powdered Chinese medicine with honey, as the latter can inhibit the radiolysis of herbs, 3. reducing the microbiological contamination in producing process and thus, requiring lower applied dose

  13. A microsecond pulse radiolysis apparatus

    International Nuclear Information System (INIS)

    A pulse radiolysis system built up in Beijing Radiation Center was described. Using a 5 MeV scanning linac as the pulse radiation source, the system could provide a 2 microsecond width and 200 mA single pulse. The non-interrupt beam monitor was used to monitor the beam current. A kinetic spectrophotometer was chosen to detect the transient optical absorption. A BCM-80A single board computer system with a transient signal recording board was used to record and process the signal and to control the time sequencing. Several pulse radiolysis experiments were carried out in aqueous system and positive results were obtained

  14. On the reaction of the C.I. Reactive Black 5 with the intermediates of water radiolysis

    International Nuclear Information System (INIS)

    Complete text of publication follows. The reactions of C.I. Reactive Black 5 in aqueous solutions with the eaq-, OH radical and H atom intermediates of water radiolysis were investigated by pulse radiolysis. The transients formed with all the three intermediates have absorption maxima at ∼360 nm, ∼410 nm and ∼470 nm. The eaq- adds to the azo group and the adduct radical anion rapidly protonates forming hydrazil radical. Based on the similar spectra the same intermediates are produced in H atom and eaq- reaction. Due to the higher reactivity, the OH radical may react in several parallel processes: the most probable way is the OH radical addition to the azo group. Moreover, the OH radical can attack to the aromatic rings. The intermediate formed in the last reaction has a high absorbance at 360 nm due to the increased conjugation of the radical site with the aromatic rings. Another possible reason for the higher absorbance can be that the hydrazil radical may react with another dye molecule forming dimer radical (RB2). The kinetic curves were measured in wide range of wavelengths and the rate coefficients were determined by fitting procedures. The buildup and the decay of the absorbance were found to follow first and simple second order behaviour, respectively

  15. Radiolysis studies at Belleville (PWR 1300) water chemistry with low hydrogen concentration

    International Nuclear Information System (INIS)

    This study has been carried out because operators sometimes find it difficult to comply with the aimed value of 25/35 ml/kg (NTP) and because the calculation codes used in the eighties did not agree on the threshold where radiolysis appeared (7 to 12 ml/kg (NTP) according to codes which were used). The aim of this document is to describe the testing conditions consisting in the observation of the effects of a decreased hydrogen concentration in primary coolant at 100% PN in reactors 1 and 2 of the Belleville plant. (authors). 3 figs., 1 tab., 3 refs

  16. Spur reaction of .H. A CIDNP study of HD in water radiolysis

    International Nuclear Information System (INIS)

    CIDNP has been detected from HD formed during radiolysis of HOD/D2O solutions under conditions where diffusive reaction of the corresponding atoms is prevented by the addition of scavengers, thus proving that at least some of the molecular hydrogen produced in spurs arises from the reaction of hydrogen atoms. The sign of the CIDNP multiplet effect indicates that the H and D atoms formed within the spur have uncorrelated electron spins. The observation of a net CIDNP polarization in HD in the presence of CD3OD is explained by reaction of e/sub aq/- and .H. 26 references, 3 figures, 1 table

  17. Pulse radiolysis

    International Nuclear Information System (INIS)

    This supplement to two bibliographies published in 1970 and 1972 lists 734 references to the literature of pulse radiolysis, arranged under eight broad subject headings. The references were compiled by searching Biological Abstracts, Chemical Abstracts, Nuclear Science Abstracts and the Weekly List of Papers in Radiation Chemistry issued by the Radiation Chemistry Data Center of Notre Dame University. Full bibliographic data is given for papers published in the period 1971 to 1974. A personal author index listing more than 600 authors and a similar number of co-authors is included

  18. The synergic impact of the boiling and water radiolysis on the pressurized water reactor fuel cladding's chemical environment

    Energy Technology Data Exchange (ETDEWEB)

    Dobrevski, I.; Zaharieva, N. [Bulgarian Academy of Sciences, Inst. for Nuclear Research and Nuclear Energy, Sofia (Bulgaria)

    2010-07-01

    By the presence of local boiling at the cladding surfaces of pressurized water reactors (PWRs), including WWER-1000 Units, the behaviors of gases dissolved in water phase (coolant) is strongly influenced by the vapor generation. The increase of vapor partial pressure will reduce the partial pressures of dissolved gases and will cause their stripping out. On the other hand it is known that the hydrogen is added to primary coolant of PWRs, in order to avoid the production of oxidants as radiolysis of water products. It is clear that if boiling strips out dissolved hydrogen, the creation of local oxidizing conditions at the cladding surfaces will be favored. In this case the local production of oxidants will be a result from local processes of water radiolysis, by which not only both oxygen (O{sub 2}) and hydrogen (H{sub 2}), but also hydrogen peroxide (H{sub 2}O{sub 2}) will be produced. While the resulting by water radiolysis hydrogen and oxygen can be stripped out preferentially by boiling, the bigger part of hydrogen peroxide will remain in the wall water phase and will act as an important factor for creation of oxidizing conditions in fuel cladding environment, together with some water radiolytical radicals: ·OH, HO{sub 2}·/ O{sub 2}{sup -}. Summarizing of the above mentioned allows the conclusion that creation of oxidizing conditions in the nuclear fuel cladding environment is not a direct boiling consequence but, in fact, is a result (consequence) of the synergic impact of the boiling- and water radiolysis- processes on the Pressurized Water Reactor fuel cladding surface areas. The PWRs experiences confirm that the density of SNB (sub-cooled nucleate boiling), resp. steaming rate, control the degree of the above mentioned water radiolysis processes. If it is not possible to moderate the steaming rate of the fuel cladding surfaces in PWRs, the only way to avoid the cladding damages caused by the local oxidizing conditions, is the applying of cladding materials

  19. Water corrosion of spent nuclear fuel:radiolysis driven dissolution at the UO2/water interface

    OpenAIRE

    Springell, Ross S; Rennie, Sophie L; COSTELLE Leila; Darnbrough, James E; Stitt, C A D; Cocklin, Elizabeth; Lucas, Chris; Burrows, Robbert; SIMS, Howard; Wermeille, Didier; RAWLE Jonathan; Nicklin, Chris; Nuttall , William; Scott, Thomas Bligh; Lander, Gerard

    2015-01-01

    X-ray diffraction has been used to probe the radiolytic corrosion of uranium dioxide. Single crystal thin films of UO2 were exposed to an intense X-ray beam at a synchrotron source in the presence of water, in order to simultaneously provide radiation fields required to split the water into highly oxidising radiolytic products, and to probe the crystal structure and composition of the UO2 layer, and the morphology of the UO2/water interface. By modeling the electron density, surface roughness...

  20. Final product analysis in the e-beam and gamma radiolysis of aqueous solutions of metoprolol tartrate

    Energy Technology Data Exchange (ETDEWEB)

    Slegers, Catherine [Universite Catholique de Louvain, Unite d' Analyse Chimique et Physico-chimique des Medicaments, CHAM 72.30, Avenue E. Mounier, 72, B-1200 Brussels (Belgium)]. E-mail: catherine.slegers@cham.ucl.ac.be; Tilquin, Bernard [Universite Catholique de Louvain, Unite d' Analyse Chimique et Physico-chimique des Medicaments, CHAM 72.30, Avenue E. Mounier, 72, B-1200 Brussels (Belgium)

    2006-09-15

    The radiostability of metoprolol tartrate aqueous solutions and the influence of the absorbed dose (0-50 kGy), dose rate (e-beam (EB) vs. gamma ({gamma})) and radioprotectors (pharmaceutical excipients) are investigated by HPLC-UV analyses and through computer simulations. The use of radioprotecting excipients is more promising than an increase in the dose rate to lower the degradation of metoprolol tartrate aqueous solutions for applications such as radiosterilization. The decontamination of metoprolol tartrate from waste waters by EB processing appears highly feasible.

  1. Final product analysis in the e-beam and gamma radiolysis of aqueous solutions of metoprolol tartrate

    Science.gov (United States)

    Slegers, Catherine; Tilquin, Bernard

    2006-09-01

    The radiostability of metoprolol tartrate aqueous solutions and the influence of the absorbed dose (0-50 kGy), dose rate (e-beam (EB) vs. gamma ( γ)) and radioprotectors (pharmaceutical excipients) are investigated by HPLC-UV analyses and through computer simulations. The use of radioprotecting excipients is more promising than an increase in the dose rate to lower the degradation of metoprolol tartrate aqueous solutions for applications such as radiosterilization. The decontamination of metoprolol tartrate from waste waters by EB processing appears highly feasible.

  2. Final product analysis in the e-beam and gamma radiolysis of aqueous solutions of metoprolol tartrate

    International Nuclear Information System (INIS)

    The radiostability of metoprolol tartrate aqueous solutions and the influence of the absorbed dose (0-50 kGy), dose rate (e-beam (EB) vs. gamma (γ)) and radioprotectors (pharmaceutical excipients) are investigated by HPLC-UV analyses and through computer simulations. The use of radioprotecting excipients is more promising than an increase in the dose rate to lower the degradation of metoprolol tartrate aqueous solutions for applications such as radiosterilization. The decontamination of metoprolol tartrate from waste waters by EB processing appears highly feasible

  3. Oxidizing dissolution of spent MOX47 fuel subjected to water radiolysis: Solution chemistry and surface characterization by Raman spectroscopy

    Science.gov (United States)

    Jégou, C.; Caraballo, R.; De Bonfils, J.; Broudic, V.; Peuget, S.; Vercouter, T.; Roudil, D.

    2010-04-01

    The mechanisms of oxidizing dissolution of spent MOX fuel (MIMAS TU2®) subjected to water radiolysis were investigated experimentally by leaching spent MOX47 fuel samples in pure water at 25 °C under different oxidizing conditions (with and without external gamma irradiation); the leached surfaces were characterized by Raman spectroscopy. The highly oxidizing conditions resulting from external gamma irradiation significantly increased the concentration of plutonium (Pu(V)) and uranium (U(VI)) compared with a benchmark experiment (without external irradiation). The oxidation behavior of the plutonium-enriched aggregates differed significantly from that of the UO 2 matrix after several months of leaching in water under gamma irradiation. The plutonium in the aggregates appears to limit fuel oxidation. The only secondary phases formed and identified to date by Raman spectroscopy are uranium peroxides that generally precipitate on the surface of the UO 2 grains. Concerning the behavior of plutonium, solution analysis results appear to be compatible with a conventional explanation based on an equilibrium with a Pu(OH) 4(am) phase. The fission product release - considered as a general indicator of matrix alteration - from MOX47 fuel also increases under external gamma irradiation and a change in the leaching mode is observed. Diffusive leaching was clearly identified, coinciding with the rapid onset of steady-state actinide concentrations in the bulk solution.

  4. Radiolysis of Starch

    International Nuclear Information System (INIS)

    In the first part of the paper the results of work on the identification and determination of the gamma (60Co) radiolysis products of maize starch are brought together and, wherever possible, a balance drawn up by chemical class. The second part of the paper deals with the main parameters governing radiolysis: dose, irradiation temperature and atmosphere, water content and the conditions under which the irradiated starch is stored. The third part, devoted to the mechanisms believed to be involved, contains the following conclusions: (a) the formation of radiation-induced products with a carbon skeleton probably results from a breaking of the → C — O — C <- chains with rearrangement of the radicals and/or a reaction involving the water and the oxygen - the oxygen has an activating effect which does not fundamentally modify the mechanism, whereas the effect of the water is more complex and varies according to the product; (b) the formation of hydrogen peroxide probably implies the addition of atmospheric oxygen to the radiation-induced hydrogen atoms in the water or to the organic radicals obtained by abstraction of a hydrogen from the starch. Lastly, the different methods envisaged for confirming or improving the mechanistic hypotheses are discussed. (author)

  5. Radiolysis of starch

    International Nuclear Information System (INIS)

    In the first part of the paper the results of work on the identification and determination of the gamma (60Co) radiolysis products of maize starch are brought together and, wherever possible, a balance drawn up by chemical class. The second part of the paper deals with the main parameters governing radiolysis: dose, irradiation temperature and atmosphere, water content and the conditions under which the irradiated starch is stored. The third part, devoted to the mechanisms believed to be involved, contains the following conclusions: (a) the formation of radiation-induced products with a carbon skeleton probably results from a breaking of the -C-O-C- chains with rearrangement of the radicals and/or a reaction involving the water and the oxygen - the oxygen has an activating effect which does not fundamentally modify the mechanism, whereas the effect of the water is more complex and varies according to the product; (b) the formation of hydrogen peroxide probably implies the addition of atmospheric oxygen to the radiation-induced hydrogen atoms in the water or to the organic radicals obtained by abstraction of a hydrogen from the starch. Lastly, the different methods envisaged for confirming or improving the mechanistic hypotheses are discussed. (author)

  6. Radiolysis Process Model

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Edgar C.; Wittman, Richard S.; Skomurski, Frances N.; Cantrell, Kirk J.; McNamara, Bruce K.; Soderquist, Chuck Z.

    2012-07-17

    Assessing the performance of spent (used) nuclear fuel in geological repository requires quantification of time-dependent phenomena that may influence its behavior on a time-scale up to millions of years. A high-level waste repository environment will be a dynamic redox system because of the time-dependent generation of radiolytic oxidants and reductants and the corrosion of Fe-bearing canister materials. One major difference between used fuel and natural analogues, including unirradiated UO2, is the intense radiolytic field. The radiation emitted by used fuel can produce radiolysis products in the presence of water vapor or a thin-film of water (including OH• and H• radicals, O2-, eaq, H2O2, H2, and O2) that may increase the waste form degradation rate and change radionuclide behavior. H2O2 is the dominant oxidant for spent nuclear fuel in an O2 depleted water environment, the most sensitive parameters have been identified with respect to predictions of a radiolysis model under typical conditions. As compared with the full model with about 100 reactions it was found that only 30-40 of the reactions are required to determine [H2O2] to one part in 10–5 and to preserve most of the predictions for major species. This allows a systematic approach for model simplification and offers guidance in designing experiments for validation.

  7. Water radiolysis by uranium fission fragments in the presence of dispersed metal oxides

    International Nuclear Information System (INIS)

    Radiation-chemical transformations in heterogeneous systems catalyst (SiO2, Li2SiO3 or BeO)-U3O8-water under effect of reactor thermal neutrons (neutron flux density of 5.8x109 or 1013 neutr./cm2xs) at 400 deg C temperature are investigated. Radiolytic hydrogen and oxygen are analyzed chromatographically . The dependence of radiolytic gas yield on water vapor density is studied. The G(H2)-water vapor density dependence curve indicates the possibility of existence of two independent processes of water decomposition in different vapor density ranges

  8. Water radiolysis in extreme conditions of temperature and LET. Scavenging of HO. by Br- ions

    International Nuclear Information System (INIS)

    The purpose of this thesis is to contribute to the understanding of the oxidation mechanism of Br- in which the HO. radical is involved. The HO. radiolytic yield is strongly connected with the oxidation yield of Br-, and therefore we have studied the influence of different physical and chemical parameters on this global yield: temperature, LET, dose rate, pH, saturation gas. The solutions have been irradiated with 4 types of ionizing rays: X-rays (from 13 to 18 keV), electrons (from 7 to 10 MeV), C6+-ions beam of 975 MeV and He2+-ions beam of 70 MeV. The development of an optical autoclave with solution flow, compatible with high LET ionizing rays has allowed us conduct the first experiments at constant high LET and high temperature. This cell has turned out to be compatible with the picosecond pump-probe experiments performed with the ELYSE accelerator. The HO. scavenging yield has been, therefore, estimated at both high LET and high temperature. A better understanding of the Br- oxidation mechanism has been achieved, in acid medium, in particular, by comparing the kinetics results with Monte Carlo Simulations for time scales inferior to the microsecond and with Chemsimul for the stable products (Br2.- and Br3- formations). (author)

  9. Radiolysis of ground water: influence of carbonate and chloride on hydrogen peroxide production

    International Nuclear Information System (INIS)

    The formation of an expanding oxidative volume by the diffusion of radiolytically formed oxidizing species out of α-irradiated volumes of pure water and synthetic ground water containing HCO3- and Cl- as principal reactive solutes is demonstrated by monitoring the H2O2 production and Fe2+ consumption in an outer aqueous phase separated from the irradiated solution by a diffusion barrier. Experimentally G(H2O2) was obtained in 'pure' water. In solutions containing HCO3- and in ground water G(H2O2) decreased. The same decrease was not found in the calculations. The discrepancy between calculated and experimental G(H2O2) for solutions containing HCO3- ions may be due to incomplete description of the radiolytic reaction mechanism for the carbonate system. (author) 9 refs.; 9 figs.; 8 tabs

  10. Radiolysis of ground water: influence of carbonate and chloride on the hydrogen peroxide production

    International Nuclear Information System (INIS)

    Small volumes of aqueous solutions have been subjected to α-radiation from a Am-241 source. The irradiated solution was separated from the bulk solution by a glass filter serving as a diffusion barrier. The H2O2 concentration in the bulk solution was monitored by a chemiluminescence technique and the overall production of oxidizing species (H2O2/O2) in irradiated ground water was studied by measuring the Fe2+-consumption in ground water initially containing 2 x 10-6 mol x dm-3 Fe2+. H2O2 yields calculated using the computer program CHEMSIMUL are in fair agreement with experimental yields for 'pure' water (pH 8) and aqueous methanol solutions (pH 5). Experimentally G(H2O2) = 1.06 +- 0.1 was obtained in 'pure' water. In solutions containing 2 x 10-3 mol x dm-3 HCO3- and in ground water G(H2O2) decreased to 0.69 +- 0.03. A corresponding decrease in G(H2O2) was not found in the calculations. The agreement between measured and calculated Fe2+ consumption is fair when slow oxidative reactions in the bulk solutions are taken into account. (authors)

  11. The measurement of aqueous radiolysis product yields at high temperature and pressure. Progress report April-September 1996

    International Nuclear Information System (INIS)

    The high temperature corrosion of the primary circuit of Boiling Water Reactors requires the oxidising products of water radiolysis in order to sustain the process. Quantification of aqueous radiolysis product yields, under the relevant high temperature and pressure regimes, is therefore an essential requirement in forecasting plant life. An experimental facility has been developed in which a proton beam can be used to irradiate water at high temperature and pressure, and to measure the production of radiolysis products. This report describes the second part of a programme of work to carry out such measurements. The work has focused on the measurement of molecular hydrogen peroxide yields, together with additional measurements of molecular hydrogen yields. Preliminary result analysis indicates that the yield of molecular hydrogen peroxide decreases as a function of temperature over the range 20 to 250oC. (author)

  12. Effect of nitrogen and oxygen on radiolysis of iodide solution

    Energy Technology Data Exchange (ETDEWEB)

    Karasawa, H.; Endo, M. [Hitachi Ltd., Power and Industrial System R+D Divisions, Ibaraki (Japan)

    1996-12-01

    The effect of nitrogen and oxygen on radiolysis of iodide solution was examined. Direct decomposition of nitrogen by {gamma}-radiation produced nitric acid to decrease a water pH. This resulted in the iodine formation in the radiolysis of iodide solution. Hydrogen peroxide was produced by the radiolysis of water containing oxygen. This worked a reducing agent to suppress the formation of iodine in the radiolysis of iodide solution. In the analytical model, fourteen iodine species were considered and reaction scheme consisted in 124 reactions. The analytical model could estimate the oxidation state of iodide ions. (author) 4 figs., 4 refs.

  13. The reaction set, rate constants and g-values for the simulation of the radiolysis of light water over the range 20 deg to 350 deg C based on information available in 2008

    International Nuclear Information System (INIS)

    An understanding of the aqueous radiolysis-induced chemistry in nuclear reactors is an important key to the understanding of materials integrity issues in reactor systems. Significant materials and chemistry issues have emerged in Pressurized Water Reactors (PWR), Boiling Water Reactors (BWR) and CANDU reactors that have required a detailed understanding of the radiation chemistry of the coolant. For each reactor type, specific computer radiolysis models have been developed to gain insight into radiolysis processes and to make chemistry control adjustments to address the particular issues. The objective of this report is to compile and review the radiolysis data now available and, where possible, correct the reported g-values and rate constants to provide a recommendation for the best values to use in high temperature modelling of light water radiolysis up to 350oC. With a few exceptions, the review has been limited to those reactions that occur in slightly acid and slightly alkaline solutions, e.g., it does not address reactions involving the oxide radical anion, O-, or ionized forms of hydrogen peroxide, HO2-, beyond their acid-base equilibria reactions. However, a few reactions have been included where the rate constant for a reaction involving O- is significantly larger than the corresponding hydroxyl radical reaction rate constant and thus can influence the chemistry below the pKA of the hydroxyl radical. (author)

  14. Calculation of initial and primary yields in the radiolysis of water

    International Nuclear Information System (INIS)

    Monte Carlo calculations have been used to model the initial physical and chemical changes, together with the subsequent diffusion-controlled reactions (up to 10-6s) which take place following the irradiation of water by electrons from 100 eV to 1 MeV. Investigations were carried out to determine the sensitivity of the radical yields to the following: vapour and liquid cross sections, the initial spatial distribution of electrons and radicals, vibrational cross sections, ionization potentials and initial electron energy for both complete tracks and also for short track sections. The roles played by the vibrational cross sections and by the relaxation of excited states through ionization were found to be most important in determining the sub-excitation electron ''entry'' energy spectrum, which in turn determines the electron thermalization distribution and therefore the primary yields. (author)

  15. Primary processes in radiation chemistry. LET (Linear Energy Transfer) effect in water radiolysis

    International Nuclear Information System (INIS)

    The effect of ionizing radiations on aqueous solutions leads to water ionization and then to the formation of radical species and molecular products (e-aq, H., OH., H2O2, H2). It has been shown that the stopping power, characterized by the LET value (Linear Energy Transfer) becomes different when the nature of the ionizing radiations is different. Few data are nowadays available for high LET radiations such as protons and high energy heavy ions. These particles have been used to better understand the primary processes in radiation chemistry. The yield of a chemical dosimeter (the Fricke dosimeter) and those of the hydrogen peroxide have been determined for different LET. The effect of the dose rate on the Fricke dosimeter yield and on the H2O2 yield has been studied too. When the dose rate increases, an increase of the molecular products yield is observed. At very high dose rate, this yield decreases on account of the attack of the molecular products by radicals. The H2O2 yield in alkaline medium decreases when the pH reaches 12. This decrease can be explained by a slowing down of the H2O2 formation velocity in alkaline medium. Superoxide radical has also been studied in this work. A new detection method: the time-resolved chemiluminescence has been perfected for this radical. This technique is more sensitive than the absorption spectroscopy. Experiments with heavy ions have allowed to determine the O2.- yield directly in the irradiation cell. The experimental results have been compared with those obtained with a Monte Carlo simulation code. (O.M.)

  16. Prediction of the oxidative dissolution rates of used nuclear fuel in a geological disposal vault due to the alpha radiolysis of water

    International Nuclear Information System (INIS)

    Effects of alpha radiolysis of water on the corrosion of nuclear fuel (UO2) have been investigated in solutions at pH = 9.5, i.e., a value close to that expected in groundwaters at the depth of the disposal vault proposed in the Canadian nuclear fuel waste management program, CNFWMP. The corrosion potentials of UO2 electrodes exposed to the products of alpha radiolysis of water were monitored as a function of alpha flux and exposure time in a specially designed thin-layer cell. The oxidative dissolution rates of UO2 are calculated form the steady-state values of the corrosion potential using an electrochemical model. A procedure to predict the dissolution rate of used nuclear fuel in groundwater as a function of fuel cooling time is described, and illustrated by calculating the dissolution rates for the reference used fuel in the CNFWMP (Bruce CANDU reactor fuel, burnup 685 GJ/kg U). It is shown that the oxidative dissolution of used fuel in the CNFWMP will be important only for time periods ≤ 600 yr at this burnup and assuming no decrease in pH

  17. Alpha radiolysis of nitric acid and sodium nitrate with 4He2+ beam of 13.5 MeV energy

    International Nuclear Information System (INIS)

    A study of aqueous nitric acid solution alpha radiolysis was performed through experiments carried out at a cyclotron facility, where a helion beam with an energy of 13.5 MeV could be delivered into the solution. The effects of nitrate and hydronium ions on the formation yields of hydrogen peroxide and nitrous acid, G(H2O2) and G(HNO2), were studied. The results showed that G(H2O2) decreases linearly with increasing nitrate ion concentration. On the other hand, G(HNO2) increases with the nitrate ion concentration until it reaches a plateau for nitric acid concentrations higher than 2 mol L–1. It was also found that an increase of hydronium ion concentration has a favorable effect on G(H2O2) and G(HNO2). Furthermore, it appears that these effects are additive and that the variations of G(H2O2) and G(HNO2) can be described by two parametric expressions, as a function of the nitrate and hydronium ion concentrations. - Highlights: • G(H2O2) decreases linearly with increasing nitrate ion concentrations. • G(H2O2) increases considerably with increasing acidity (up to [H+]=0.5 mol L−1). • G(HNO2) increases with increasing nitrate and hydronium concentrations until a plateau is reached. • The effects of nitrate and hydronium ions on G(H2O2) and G(HNO2) are additive

  18. Experiments about the integrity of BWR relief pipes in postulated radiolysis gas combustion. Scenario No.1. Steam leakages with full lowering of the water level

    International Nuclear Information System (INIS)

    Experiments in a pipe of the original scale, original material, and original quality control were carried out to study the maximum possible loads potentially arising in the combustion of radiolysis gas / nitrogen mixtures in BWR relief pipes with full lowering of the water level. Peak pipe loads resulted for narrow ranges of concentration around 43% N2 (for 0.8 bar initial pressure) and 50% N2 (for 1.6 bar initial pressure), respectively. With these mixtures, ignition of the homogeneous H2/O2/N2 mixture is followed by a deflagration - detonation transition in pre-compressed unburnt gas only a short distance upstream of the end flange. This phenomenon generally occurs when, in the combustion gas studied, the starting distance for detonation transition becomes comparable to the pipe length. No strains higher than 0.2% were measured in any of the experiments. The dynamic pipe load remained in the elastic range in all experiments performed, which also prevented the pipe from being damaged in the course of a test series. The pipe was not subjected to any major axial forces and accelerations in the experiments. This constitutes experimental proof, under conservative boundary conditions, of the integrity of relief pipes even in the case of assumed complete filling with the most adverse radiolysis gas mixture and subsequent combustion. (orig.)

  19. SimulRad: a Java interface for a Monte-Carlo simulation code to visualize in 3D the early stages of water radiolysis

    International Nuclear Information System (INIS)

    Using a Fortran step-by-step Monte-Carlo simulation code of liquid water radiolysis and the Java programming language, we have developed a Java interface software, called SimulRad. This interface enables a user, in a three-dimensional environment, to either visualize the spatial distribution of all reactive species present in the track of an ionizing particle at a chosen simulation time, or present an animation of the chemical development of the particle track over a chosen time interval (between ∼10-12 and 10-6 s). It also allows one to select a particular radiation-induced cluster of species to view, in fine detail, the chemical reactions that occur between these species

  20. Radiolysis Model Sensitivity Analysis for a Used Fuel Storage Canister

    Energy Technology Data Exchange (ETDEWEB)

    Wittman, Richard S.

    2013-09-20

    This report fulfills the M3 milestone (M3FT-13PN0810027) to report on a radiolysis computer model analysis that estimates the generation of radiolytic products for a storage canister. The analysis considers radiolysis outside storage canister walls and within the canister fill gas over a possible 300-year lifetime. Previous work relied on estimates based directly on a water radiolysis G-value. This work also includes that effect with the addition of coupled kinetics for 111 reactions for 40 gas species to account for radiolytic-induced chemistry, which includes water recombination and reactions with air.

  1. Radiolysis of sulphanilamide

    International Nuclear Information System (INIS)

    Radiolysis of sulphanilamide has been investigated with concentration varied from 10-4 to 10-3 Molar, and doses of 1 to 5 kGy. The products were analyzed on high pressure liquid chromatograph and thin layer chromatograph. The products were supposed to be sulphanilic acid, 3-hidroxy sulphanilamide. (author)

  2. Contribution to the study of solvated electrons in water and alcohols and of radiolytic processes in organic carbonates by picosecond pulse radiolysis

    International Nuclear Information System (INIS)

    This work is part of the study area of the interaction of radiation with polar liquids. Using the picosecond electron accelerator ELYSE, studies were conducted using the techniques of pulse radiolysis combined with absorption spectrophotometry Time-resolved in the field of a picosecond. This work is divided into two separate chapters. The first study addresses the temporal variation of the radiolytic yield of solvated electron in water and simple alcohols. Due to original detection system mounted on the accelerator ELYSE, composed of a flash lamp specifically designed for the detection and a streak-camera used for the first time in absorption spectroscopy, it was possible to record the time-dependent radiolytic yields of the solvated electron from ten picoseconds to a few hundred nanoseconds. The scavenging of the electron solvated by methyl viologen, was utilized to reevaluate the molar extinction coefficient of the absorption spectrum of solvated electron in water and ethanol from isobestic points which corresponds to the intersection of the absorption spectra of solvated electron which disappears and methyl viologen which is formed during the reaction. The second chapter is devoted to the study of liquid organic carbonates such as dimethyl carbonate (DMC), diethyl carbonate (DEC) and propylene carbonate (PC). This family of carbonate which compose the electrolytes lithium batteries, has never been investigated by pulse radiolysis. The studies were focused on the PC in the light of these physicochemical characteristics, including its very high dielectric constant and its strong dipole moment of 4.9 D. The first results were obtained on aqueous solutions containing propylene carbonate to observe the reactions of reduction and oxidation of PC by radiolytic species of water (solvated electron and OH radicals). Then, after the identification (spectral and kinetic) of the species formed by interaction with the OH radical as the PC* radical resulting from the

  3. Experiments about the integrity of BWR relief pipes in postulated radiolysis gas combustion. Scenario No.2. Minor steam leakages without any lowering of the water level

    International Nuclear Information System (INIS)

    The experiments described in this article were performed to study this comprehensive radiolysis gas scenario: - The relief pipe is filled completely with radiolysis gas (2H2+O2). - After opening of the S and R valve, the radiolysis gas is compressed adiabatically by the incoming steam without mixing. - Roughly at the point of peak pressure in the relief pipe (20 bar) the radiolysis gas ignites. This dynamic scenario was studied in steady-state model experiments with a test pipe which corresponds to the relief pipes installed in KKP-1 in terms of materials, dimensions, and manufacturing control. The initial conditions and boundary conditions of the experiments were conservative. In the course of the tests, the maximum dynamic strain and the residual plastic deformation of the test pipe were measured via the transient detonation load. The maximum dynamic strain measured was 0.75%, the maximum residual plastic strain reached 0.15%. The pipe suffered no other deformation above and beyond this slight plastic strain. The radiolysis gas detonation was simulated very well numerically. Using the calculated pressure loads in a structural dynamics model also showed good agreement with the measured maximum dynamic pipe strains. In this way, the experimental findings were confirmed theoretically. The experiments and the calculations showed that postulated radiolysis gas reactions during pressure relief cannot jeopardize the integrity of the relief pipe. (orig.)

  4. Radiolysis of phenol in aqueous solution at elevated temperatures

    International Nuclear Information System (INIS)

    γ-Radiolysis and pulse radiolysis of phenol in aqueous solution up to supercritical condition have been carried out. G-values of phenol consumption and product formation have been determined. While dihydroxybenzenes were major products at room temperature, multi-ring compounds and benzene were formed above 300 deg. C. This indicates reaction mechanism was changed above 300 deg. C, where phenoxyl radical plays a predominant role. This is supported by the observation of phenoxyl radical in pulse radiolysis. In supercritical water, the G-values increased with decrease of density

  5. Verification and validation procedures of calculation codes for determining corrosive conditions in the BWR primary cooling system based on water radiolysis and mixed potential models

    International Nuclear Information System (INIS)

    Corrosive conditions in the BWR primary cooling system are usually expressed by the corrosion index, ECP. In order to determine ECP at any location in the primary cooling system, ECP should be evaluated by computer simulation codes consisting of water radiolysis models to determine the concentrations of corrosive radiolytic species and mixed potential models to determine ECP based on corrosive species. Measures for mitigation of SCC crack growth rate by decreasing ECP are authorized by the JSME Standards; however, measures for mitigation of ECP by hydrogen addition have not been authorized yet. In the paper, standard procedures to authorize the computer simulation codes based on the verification and validation (V and V) method are proposed. The numerical justification of every code applied as a standard code should be verified and its accuracy and applicability for plant analysis should be validated. Benchmark analysis for verification procedures is proposed while a comparison of the calculated results with the measured ones for the evaluated plant is also proposed for the validation procedures. It is strongly recommended that the results of V and V evaluation of the codes that might be applied for evaluation of corrosive conditions in operating power plants are published in a peer-reviewed journal before their application. (author)

  6. Pulse radiolysis of gases

    International Nuclear Information System (INIS)

    The pulse radiolysis equipment and technique are described and its relevance to atmospheric chemistry is discussed. Pulse radiolysis of a number of different chemical systems have been used to check the validity of the proposed mechanisms: 1) The hydrogen atom yield in the pulse radiolysis of H2 was measured by four independent calibration techniques, using reactions of H with O2, C1NO, and HI. The H atom yield was compared with O2 yields in pure O2 and in O2/SF6 mixtures which lead to a value G(H) = 17.6. The rate constants at room temperature of several reactions were determined. 2) OH radical reactions with tetraalkyllead at room temperature and with ethane, methane, and a series of C1- and F-substituted methanes at 300-400 K were studied. Arrhenius parameters, A and Esub(a), were determined for several reactions. The lifetime of Pb(CH3)4 and Pb(C2H5)4 in ambient air is estimated. CF2C12 was found to be a very efficient third body, M, in the reaction OH + OH + M arrow H2O2 + M. 3) In the H2S systems the HS extinction coefficient at 3242 AA was determined to 9.5 x 102 cm-1 mol-1. Four rate constants at room temperature were determined. (author)

  7. Water/polyethylene system radiolysis: application to the tritiated water storage in polyethylene bottle; Radiolyse du systeme eau/polyethylene: application au stockage d'eau tritiee en bonbonne polyethylene

    Energy Technology Data Exchange (ETDEWEB)

    Billamboz, N.

    2007-04-15

    This study deals with the validation and the search of the limitations for the storage of tritiated water (HTO) in polyethylene (PE) containers. The hydroxyl radical (HO{sup .}), produced during the radiolysis of water, is known for its reactivity toward alkanes in water. Our competition experiments (with SCN{sup -} or coumarin) by pulse radiolysis shows the reactivity of HO{sup .} with PE, which gives rise to chemical modifications of PE. Some FTIR analysis of PE, irradiated in the presence of water, show that the amounts of C=C, C-O, and C=O functions are more important when the production of HO{sup .} is favoured. Moreover the reactivity of e{sub aq}{sup -} in the presence of PE has also been highlighted by time resolved spectroscopy. The study of permeability of the HTO/PE system shows that the volumetric activity within PE is 10{sup 4} fold lower than the water activity after a one year immersion in 1853 Ci.L{sup -1} HTO. The MCNP simulation of the irradiation by the {beta}{sup -} of the tritium points out that 200 kGy is deposited within the first 250 nanometers of the PE. In spite of an early diffusion these results show a very weak solubility. Furthermore the value of the diffusion decreases following the modifications induced by the {beta}{sup -} at the surface. Crosslinking is a parameter that directly acts on the diffusion of molecules through the polymer. We have adapted and used the thermo-poro-metry technique in order to assess the crosslinking of PE. Using this investigation we have characterized the cross linking as a function of the dose, especially with respect to the mesh size distribution. We have also established a relationship allowing the determination of the crosslinking density in a swelled PE sample by p-xylene by DSC analysis. (author)

  8. Nuclear power plant conference 2010 (NPC 2010): International conference on water chemistry of nuclear reactor systems and 8th International radiolysis, electrochemistry and materials performance workshop

    International Nuclear Information System (INIS)

    The Nuclear Plant Chemistry Conference was held in Quebec City, Quebec, Canada on October 3-7, 2010. It was hosted by the Canadian Nuclear Society and was held in Canada for the first time. This international event hosted over 300 attendees, two thirds from outside of Canada, mostly from Europe and and Far East. The conference is formally known as the International Conference on Water Chemistry of Nuclear Reactor Systems and is the 15th of a series that began in 1977 in Bournemouth, UK. The conference focussed on the latest developments in the science and technology of water chemistry control in nuclear reactor systems. Utility scientists, engineers and operations people met their counterparts from research institutes, service organizations and universities to address the challenges of chemistry control and degradation management of their complex and costly plants for the many decades that they are expected to operate. Following the four day conference, the 8th International Radiolysis, Electrochemistry and Materials Performance Workshop was held as associated, but otherwise free-standing event on Friday, October 8, 2010. It was also well attended and the primary focus was the effect of radiation on corrosion. When asked about the importance of chemistry in operating nuclear power plants, the primary organizers summarized it in the following statement: 'Once a nuclear plant is in operation, chemistry improvement is the only way to increase the longevity of the plant and its equipment'. The organisers of the 2010 Workshop and the NPC 2010 conference decided that these two events would be held consecutively, as previous, but for the first time the organization and registration would be shared, which proved to be a winning combination by the attendance.

  9. Study on radiation-induced reaction in microscopic region for basic understanding of electron beam patterning in lithographic process. 1. Development of subpicosecond pulse radiolysis and relation between space resolution and radiation-induced reactions of onium salt

    International Nuclear Information System (INIS)

    In the acid generation processes of chemically amplified electron beam and X-ray resists, the ionization of a base resin plays an important role. A proton is generated from the cation radical of the base resin. On the other hand, a counter anion is generated from an acid generator after the reaction of the acid generator with the electron generated by the ionization of the base resin. In the resist materials in which both the radical cation of base resin and the electron play important roles in forming a latent image, the initial separation distance between the cation radical and the electron and the subsequent reactions immediately after irradiation are important for the fabrication of nanoscale patterns. For the understanding of electron beam and X-ray patterning, we developed a subpicosecond pulse radiolysis system for conducting the absorption spectroscopy and investigated the reactions of onium salt. The onium salt efficiently reacts with an electron generated by ionization. The high efficiency of reaction of an onium salt with an electron is thought to block the migration of a thermalized electron in the resist matrix and prevent the degradation of the space resolution of resists caused by the migration of the thermalized electron. (author)

  10. Study of initial process of radiation chemistry using UV-VIS-NIR femtosecond pulse radiolysis

    International Nuclear Information System (INIS)

    Measureable wavelength of femtosecond pulse radiolysis system was expanded 2000 nm in near infrared region to 240 nm in ultra violet region. By stabilization of measurement system, signal to noise ration in absorbance measurement was improved and 1 mOD can be measured. In various material such as water, alkanes, and polymers, spectral change and time profile of active species on radiation induced initial process can be measured in femtosecond time region. Especially in dodecane, time profile on progressing of geminate ion recombination. In this paper, derivative effect for in application of ultra short electron beam which was generated by a photocathode rf gun linac. (author)

  11. On the formation of a moving redox-front by α-radiolysis of compacted water saturated bentonite

    International Nuclear Information System (INIS)

    The formation of an expanding volume containing the radiolytically formed oxidants H2O2 and O2 has been studied in α-irradiated compacted water saturated bentonite (ρ = 2.12 gxcm-3). The G-values (0.67±0.05), (0.64±0.07) for H2O2 and O2 respectively are in fair agreement with the corresponding G-values obtained in experiments with synthetic ground water. From the leaching of γ-irradiated bentonite it is concluded that only a fraction of the Fe2+ content is easily accessible as scavenger for the radiolytically formed oxidants. (orig.)

  12. Study of water radiolysis in relation with the primary cooling circuit of pressurized water reactors; Etude sur la radiolyse de l`eau en relation avec le circuit primaire de refroidissement des reacteurs nucleaires a eau sous pression

    Energy Technology Data Exchange (ETDEWEB)

    Pastina, B

    1997-07-01

    This memorandum shows a fundamental study on the water radiolysis in relation with the cooling primary circuit of PWR type reactors. The water of the primary circuit contains boric acid a soluble neutronic poison and also hydrogen that has for role to inhibit the water decomposition under radiation effect. In the aim to better understand the mechanism of dissolved hydrogen action and to evaluate the impact of several parameters on this mechanism, aqueous solutions with boric acid and hydrogen have been irradiated in a experimental nuclear reactor, at 30, 100 and 200 Celsius degrees. It has been found that, with hydrogen, the water decomposition under irradiation is a threshold phenomenon in function of the ratio between the radiation flux `1` B(n, )`7 Li and the gamma flux. When this ratio become too high, the number of radicals is not sufficient to participate at the chain reaction, and then water is decomposed in O{sub 2} and H{sub 2}O{sub 2} in a irreversible way. The temperature has a beneficial part on this mechanism. The iron ion and the copper ion favour the water decomposition. (N.C.). 83 refs.

  13. Coolant radiolysis studies in the high temperature, fuelled U-2 loop in the NRU reactor

    Energy Technology Data Exchange (ETDEWEB)

    Elliot, A.J.; Stuart, C.R. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2008-06-15

    An understanding of the radiolysis-induced chemistry in the coolant water of nuclear reactors is an important key to the understanding of materials integrity issues in reactor coolant systems. Significant materials and chemistry issues have emerged in Pressurized Water Reactors (PWR), Boiling Water Reactors (BWR) and CANDU reactors that have required a detailed understanding of the radiation chemistry of the coolant. For each reactor type, specific computer radiolysis models have been developed to gain insight into radiolysis processes and to make chemistry control adjustments to address the particular issue. In this respect, modelling the radiolysis chemistry has been successful enough to allow progress to be made. This report contains a description of the water radiolysis tests performed in the U-2 loop, NRU reactor in 1995, which measured the CHC under different physical conditions of the loop such as temperature, reactor power and steam quality. (author)

  14. Coolant radiolysis studies in the high temperature, fuelled U-2 loop in the NRU reactor

    International Nuclear Information System (INIS)

    An understanding of the radiolysis-induced chemistry in the coolant water of nuclear reactors is an important key to the understanding of materials integrity issues in reactor coolant systems. Significant materials and chemistry issues have emerged in Pressurized Water Reactors (PWR), Boiling Water Reactors (BWR) and CANDU reactors that have required a detailed understanding of the radiation chemistry of the coolant. For each reactor type, specific computer radiolysis models have been developed to gain insight into radiolysis processes and to make chemistry control adjustments to address the particular issue. In this respect, modelling the radiolysis chemistry has been successful enough to allow progress to be made. This report contains a description of the water radiolysis tests performed in the U-2 loop, NRU reactor in 1995, which measured the CHC under different physical conditions of the loop such as temperature, reactor power and steam quality. (author)

  15. Nuclear magnetic resonance in pulse radiolysis. II. CIDNP in radiolysis of aqueous solutions

    International Nuclear Information System (INIS)

    Applications of magnetic resonance to the study of radiolysis are illustrated. The products of radiolytically produced radicals exhibit CIDNP when examined, seconds after their creation, by NMR. Irradiation with a pulsed electron beam (3 MeV) was carried out in variable magnetic fields and the irradiated solutions were transferred to the NMR sample tube using a fast flow system. Aqueous solutions of methanol, iodomethane, ethylene glycol, acetate, and chloroacetate were studied. In these systems CIDNP in numerous products and starting materials can be observed. The ''primary radicals'' of radiolysis e/sub aq/- and H play a significant role in the polarization pathways. Applicability of the radical pair model of CIDNP to radiation chemistry is illustrated

  16. State of knowledge on the water radiolysis in cemented wasteforms and its approach by simulation; Etat des connaissances sur la radiolyse de l'eau dans les colis de dechets cimentes et son approche par simulation

    Energy Technology Data Exchange (ETDEWEB)

    Bouniol, P

    2004-07-01

    The decomposition of water under radiation within the cementitious matrix is at the origin of a potential source of harmful effects in the wasteform and their environment (pressurization and emanation of di-hydrogen) which can have an impact on the safety. In the aim of a better evaluation of the 'H{sub 2}' risk induced by such a complex and heterogeneous system, this document is an analysis of the elements necessary for a global understanding of the radiolysis in the cemented wasteform to be achieved: - summary of the basic knowledge on water radiolysis with transposition to the cementitious medium, - critical review of the various phenomenologies at work in a wasteform (radioactive source-term, gas transport, mineral equilibria); description of their mutual couplings and of their feedback on radiolytic chemistry; identification of the determining parameters, - presentation of a selection of experimental facts putting in light some theoretical points, - presentation of an outline of operational model deriving from the global vision; presentation of an adapted tool for simulation (CHEMSIMUL) and study of the influence of the principal parameters, starting from a reference case. The main result of this work is that it is shown, in the case of a {beta}{gamma} source term, that the control of the pore fluid composition by calcium octo-hydrate peroxide constitutes an efficient regulating mechanism for the radiolysis and H{sub 2} production. Not likely possible in the case of an {alpha} source term, this suggests a separate management of the wasteform according to their radiological contents. The gaps and limits of the model which are also evoked are promising of a lot of research prospects, primarily of a fundamental nature (impact of the porous medium). (author)

  17. Radiolysis of DNA and other biopolymers

    International Nuclear Information System (INIS)

    Studies of radiolysis of biopolymers serve the dual purposes of giving information on (a) chemical mechanisms by which radiation modifies life processes and (b) structure-function relationships in macromolecules. Conditions in living cells are such that both direct and indirect depositions of energy in biopolymers are possible. Direct effects in chromatin components result in formation of specific radical products, many highly reactive. In irradiated DNA the cationic radical, Gua+, and the anionic radical, Thy-, make large contributions to the electron spin resonance (ESR) spectrum. Secondary reactions of the cationic radicals are largely unknown. Indirect effects occur when energy is deposited in water or other components in a solution, and radiolysis products such as e/sub aq/- and hydroxy radicals react with the biopolymer under investigation. Conversion of hydroxy radicals to the less reactive inorganic radical-anion Br2- has made it possible to determine the role of tyrosine in functional and structural integrity of several proteinase inhibitors. Both e/sub aq/- and hydroxy radicals react rapidly with DNA, but only hydroxy radicals initiates reactions which damage DNA. Radiolysis of double-stranded DNA leads to an increase in optical absorption. The hydroxy radicals is believed to attack the deoxyribose moiety, causing strand breaks and partial denaturation, thus reducing the hypochromic effect. After the DNA is partially denatured, or single-stranded, hydroxy radicals attacks the bases also. Three kinds of strand breaks have been observed; (1) immediate, (2) those appearing post-irradiation, and (3) those appearing on post-irradiation treatment with alkali. Radiolysis of chromatin results in DNA strand breaks, base damage, and protein-DNA cross links. Yields for strand breaks and base damage are lower in chromatin than in purified DNA, and lower still in intact cells

  18. Investigations of pipeline reactions to detonations of radiolysis gas

    International Nuclear Information System (INIS)

    As a case of damage in a head spray cooling piping of a boiling-water reactor showed, detonations of radiolysis gas in safety-relevant tubes of nuclear power plants cannot be excluded in all cases. Radiolysis gas is a mixture of gaseous hydrogen and oxygen in stoichiometric ratio which is generated by dissociation of water under the influence of gamma and neutron radiation. Within the scope of a research project funded by the Federal Ministry of Economics and Technology (BMWi) the basis for the assessment of the related risk potential for plant operation shall, among others, be provided. Due to the high-rate response of the pipe to the detonation, multiple longitudinal cracks and fragmentation can occur. Detonation tests and numerical evaluations are performed to simulate detonations of radiolysis gas in thin-walled pipes. The radiolysis gas is simulated by mixing hydrogen and oxygen from gas bottles. Pipes made of austenitic steel with the nominal dimensions of OD x t = 114,30 mm x 6,02 mm are used for the tests. The internal pressure is 70 bar in all cases. In different tests, which are carried out at room temperature, the ratio of radiolysis gas in the pipe is varied and for the simulation of steam nitrogen is used as another filling medium. Next to the results of three detonation tests with a radiolysis gas ratio of 60% and 80% the results of tests, carried out for the experimental evaluation of the radiolysis gas reactions, with thick-walled vessels are presented. (orig.)

  19. Radiolysis of Aqueous Toluene Solutions

    International Nuclear Information System (INIS)

    Aqueous toluene solutions have been irradiated with Co γ-rays. In unbuffered solutions the various cresol isomers are formed in a total yield of 0.45, 0.87 and 0.94 molecules/100 eV absorbed energy in argon-, N2O- and air - saturated solutions, respectively. The yields are reduced in acid (pH 3) solutions (G 0.14, 0.14 and 0.52, respectively) but the reduction is compensated by the formation of 1,2-di-phenylethane in yields of 0.49 and 1.60 in argon- and N2O-saturated solutions, respectively. Benzyl radicals are formed through an acid catalysed water elimination reaction from the initially formed hydroxymethylcyclohexadienyl radical. Phenyltolylmethanes, dimethylbiphenyls and partly reduced dimers are also formed during the radiolysis. Hydrogen is formed in the same yield as the molecular yield, g(H2). Xylene isomers and benzene are formed in trace quantities. The most remarkable effects of the addition of Fe(III) ions to deaerated acid toluene solutions are the formation of benzyl alcohol and benzaldehyde and an increase in the yield of 1,2-diphenylethane

  20. Polymeric (HO) radical scavenger for waste water treatment by electron beam radiation

    International Nuclear Information System (INIS)

    Electron beam irradiation is an important technique for removing heavy metal ions from their solutions especially of high concentrations. Scavengers HO radical were used to prevent metals from re oxidation and reduce the energy used. for this purpose four scavengers HO radicals were used acetic acid, alcohol, a cationic detergent and humic acid to illustrate the influence of different species generated by water radiolysis to remove these ions. The experiments were carried out on model solutions containing five metals: Cr6+, Co2+, Cu2+, Ni2+ and Pb2+ at different irradiation doses 5 - 75 KGy, different concentrations of about 0.1 - 30 and 100 ppm, different pHs 2.7 and 8 in presence and absence of scavengers. Produced removal around 96 - 100% in presence of HO scavengers during irradiation like humic acid as a natural organic polymer. The detergent removed 100% in diluted solutions and 76% for concentrated ions, Acetic acid produced 99.9% removal for chromium .. Alcohol (Ethanol) produced removal percent of 98.3 for dilute aqueous solutions and 82.7% for concentrated ones.

  1. Density dependence of the spur lifetime and the 'escape' hydrated electron yield in the low-LET radiolysis of supercritical water at 400°C

    International Nuclear Information System (INIS)

    The 'spur lifetime' (τs) in the low-LET radiolysis of supercritical water (SCW) at 400 °C has been determined as a function of density by using a simple model of energy deposition initially in spurs, followed by the random diffusion of the species formed until spur expansion is complete. The values of τs are found to decrease from ~5.0 x 10-6 to ~5.0 x 10-8 s over the density range ~0.15 to 0.6 g/cm3. Using Monte-Carlo simulations, our calculated density dependence of the 'escape' hydrated electron (e-aq) yield (i.e., at time τs) reproduces fairly well Bartels and co-workers' scavenged e-aq yield data, strongly suggesting that these data may have been measured at time close to τs. (author)

  2. Electrochemical behaviour of stainless steel in PWR primary coolant conditions: Effects of radiolysis

    Science.gov (United States)

    Muzeau, Benoist; Perrin, Stéphane; Corbel, Catherine; Simon, Dominique; Feron, Damien

    2011-12-01

    Few data are available in the literature on the role of the water radiolysis on the corrosion of stainless steel core components in PWR operating conditions (300 °C, 155 bar). The present approach uses a high energy proton beam to control the production of radiolytic species at the interface between a stainless steel sample and water in a high temperature and high pressure (HP-HT) electrochemical cell working in the range 25 °C/1 bar-300 °C/90 bar. The cell is designed to record the free corrosion potential of the AISI 316L/water interface mounted in line with a cyclotron delivering the proton beam. The evolution of the potential is compared before, during and after the proton irradiation. The first results are obtained with an aqueous solution containing boron, lithium and dissolved hydrogen, as in PWR primary coolant circuit. The stainless steel/water interfaces are irradiated between 25 °C and 300 °C with protons emerging at 22 MeV at the interface. The flux is varied by five orders of magnitude, from 6.6 × 10 11 to 6.6 × 10 15 H + m -2 s -1. The evolution of the free corrosion potential is highly dependent on the temperature and/or pressure. For a given temperature and pressure, it evolves with the flux and the ageing of the AISI 316L/water interfaces. An important role of the temperature of irradiation on the electrochemical response was observed. These results give a better understanding of the role of radiolysis on stainless steel corrosion in high temperature conditions.

  3. Development of dispersant technology in primary systems of light water reactors. Radiolysis of polyacrylic acid under PWR primary condition and dissolution experiments of metal oxides

    International Nuclear Information System (INIS)

    In order to develop a new technology of dispersant addition into primary coolant of nuclear power reactors and to achieve sufficient reduction of the radiation exposure, radiolysis of poly acrylic acid (PAA) solution was investigated under the PWR primary condition. PAA solution was irradiated by gamma-rays at 320degC up to 10 kGy and 100 kGy. After irradiation, TOC concentration and molecular weight significantly decreased. Carbon dioxide and acetate were detected as radiolytic products with relatively low yields. Radiation chemical simulation at 300degC demonstrated that PAA is consumed at around 5 kGy. It is considered that scission of PAA radicals is predominant up to several kGy where as disproportionation seem major reaction of PAA radicals at higher absorbed dose. Screening experiments were carried out to select promising chemical agent under the condition of BWR coolant. Immersion tests of iron oxide at 180degC in the presence of various chemical agent showed that Fe concentration was highest in the presence of PAA (weight-average molecular weight = 16,000). It was concluded that the PAA is the most promising chemical agent to remove corrosion products in BWR coolant systems. (author)

  4. Nuclear magnetic resonance in pulse radiolysis. Chemically induced dynamic nuclear polarization

    International Nuclear Information System (INIS)

    Nuclear magnetic resonance and chemically induced dynamic nuclear polarization (CIDNP) were applied to the study of pulse radiolysis. Samples were irradiated with a 3-MeV electron beam from the Argonne Van de Graaff accelerator in an EPR magnet (approximately 4000 G) which had axial holes for beam access. A fast flow system transferred the irradiated solution to the rotating 5-mm NMR sample tube. The NMR spectra of mixtures of sodium acetate and methanol were presented to demonstrate the features of the CIDNP in pulse radiolysis

  5. Shear Strength of Reinforced Concrete Beams Under Sea Water

    Institute of Scientific and Technical Information of China (English)

    阎西康; 王铁成; 张玉敏

    2004-01-01

    The marine structures such as harbour,pier and inshore concrete terrace are exposed in adverse circumstances in a long period of time . Owing to the attack of external corrosive medium, their safety, durability and reliability decline. Especially the reinforced concrete(RC) structures in the wave splash area are more likely to be subjected to destruction and the loss is vast. Now the safety ,durability and reliability of structure have become increasingly an important subject to be studied. By way of the soaking and drying cycle test on the different mix proportions oblique section of 10 pieces of RC beams suffered artificial sea water(ASW) corrosion under 0,35,70,105,140 times of dry-wet cycles ,the compared results of exerting pressure test of these beams under simply supporting were investigated. The law about the changes of the mechanical performance for RC beams with different mix proportions under different time periods for suffering corrosion of dry-wet cycles is as follows: the resistivity to ASW corrosion of the concrete specimens with various water cement ratio( various initial strength) is different; the characters of oblique section failure for RC beams attacked by sea water are about the same as those for ordinary RC beam; along with the extension of the time for sea water attack, the bearing capacity for oblique section of RC beams varies wave upon wave. The specimens attacked by sea water for about 35 times of corrosion cycle achieve minimum bearing capacity.

  6. gamma-radiolysis and pulse radiolysis of aqueous 4-chloroanisole

    DEFF Research Database (Denmark)

    Quint, R.M.; Park, H.R.; Krajnik, P.;

    1996-01-01

    after T-radiolysis in dependence of dose (100-600 Gy) are given for N2O-, air-, oxygen- and argon saturated neutral aqueous solutions. In conditions favoring the OH radical oxidation 4-chlorophenol, 4-methoxyphenol, 5-chloro-2-methoxyphenol and 2-chloro-5-methoxyphenol were determined as final products...... quantitatively to the degradation of the substrate. In the presence of air or solutions saturated with pure oxygen predominantly hydroquinone. 4-chlorophenol and muconic acids are formed and the material balance is similar to 50%. The efficient dechlorination (similar to 66% of the decomposed 4-CIAn) as well as...

  7. Yields of hydrogen peroxide in radiolysis of aqueous ethylene glycol solutions

    International Nuclear Information System (INIS)

    The main source of information on mechanisms for the formation of H2O2 and other molecular water radiolysis products is the dependence of their yields on the concentration of a substance (S) dissolved in the water. A diffusion/recombination model for water radiolysis predicts that at low (≤0.1 mole/dm3) concentrations of S in water (C/sub S/) the yields of molecular water radiolysis products (G/sub M/), i.e., H2 and H2O2, drop linearly with the cube root of C/sub S/. This paper attempts to prove the assumption experimentally by studying how G/sub H2O2/, the ideal water breakdown yield, is affected by high concentrations of ethylene glycol in deaerated aqueous solutions. The observed radiolytic yield of H2O2 in this system agreed with the initial G/sub H2O2/

  8. Corrosion of target and structural materials in water irradiated by an 800 MeV proton beam

    International Nuclear Information System (INIS)

    Radiation enhanced, aqueous corrosion of solid neutron-targets such as tungsten or tantalum, or target cladding or structural materials such as superalloys and stainless steels, is a significant concern in accelerator-driven transmutation technologies. In this paper we briefly describe our current methods for control and in situ monitoring of corrosion in accelerator cooling water loops. Using floating, electrochemical impedance spectroscopy (EIS), we have measured the corrosion rates of aluminum 6061, copper, Inconel 718, and 304L stainless steel in the flow loop of a water target irradiated by a μamp, 800 MeV proton beam. Impedance spectroscopy allows us to model the corrosion process of a material as an equivalent electrical circuit. Thus the polarization resistance, which is inversely proportional to the corrosion rate, can be extracted from the frequency response of a metal specimen. During a three month period, without the use of corrosion mitigation techniques, we observed increases of several orders of magnitude in the water conductivity and the corrosion rates. The increase in corrosion is at least partially attributed to a build up of peroxide in our pseudo-closed loop system. In this paper we also briefly describe our second generation experiments, scheduled to begin in late 1996. In these experiments we plan to measure the corrosion rates of tungsten, tantalum, Inconel 718, 316L and 304L stainless steel, HT-9 austenitic stainless steel, and aluminum 5053. Two or three electrode probes of each material are being placed directly in the proton beam, in a high neutron flux region, or a significant distance from the high radiation area. We will be measuring corrosion rates, changes in pH and conductivity, and we will be establishing parameters for filtration and mitigation of corrosion. We will also discuss our ideas for making in situ measurements of water radiolysis using optical and laser diagnostic techniques

  9. Radiolysis of starch

    International Nuclear Information System (INIS)

    The amounts of formed desoxy-compounds, which produce malonic dialdehyde during HIO4-oxydation, as well as that of ω-hydroxymaltol have been determined in irradiated potato starch and irradiated wheat flour in dependence on irradiation doses. With pure potato starch, G-values of 0.03-0.04 for water soluble dosoxy-compounds and such ones of 0.02 for insoluble desoxy-compounds were obtained. G-values of desoxy-compounds in an ethyl acetate-acetone-water extract (4 : 5 : 1 v/v) of irradiated potato starch and irradiated wheat flour showed a ratio of about 3 : 1. When aqueous potato starch sols are irradiated desoxy-groups in the high-molecular starch molecule will also be found (in N2O atmosphere: G-values around 0.3). With ω-hydroxymaltol it became apparent that the main part of this compound is formed after irradiation during storage. With pure potato starch G-values around 0.015-0.02 were determined after 10 days of storage. When this material is heated after irradiation an increase of the hydroxy-maltol content (G-values: 0,025) is to be found. In the non-irradiated materials traces of desoxy-compounds as well as ω-hydroxymaltol were found. (orig.)

  10. Electron beam sterilization of water discharged from sewage

    International Nuclear Information System (INIS)

    At present, the water treated at city sewerages is discharged to rivers after the chlorine sterilization, but it was clarified recently that this chlorine treatment produces carcinogenic organic chlorine compounds, and residual chlorine exerts harmful effect to aquatics, therefore, it is desirable to develop the sterilization techniques substituting for chlorine treatment. Already many reports elucidated that irradiation is effective for the sterilization of the water discharged from sewerage. However, as the technical subject for putting radiation process in practical use, the treatment of large quantity was a problem. Recently by the progress of the technology of manufacturing electron accelerators, the equipment with large power output which can treat in large quantity was developed, and it has become applicable also to sewage treatment. Therefore, the authors examined the practicality of electron beam process as the substitute technology for chlorine sterilizaiton. In the case of using electron beam, though the power output of accelerators is large, the flight range of electron beam in water is short. The comparison of the sterilization effect of electron beam with that of Co-60 gamma ray, the effects of water depth, discharged water quality and water velocity on the sterilization effect and so on were experimentally examined. (K.I.)

  11. Radiolysis of crystalline nickel oxalates

    Science.gov (United States)

    Basahel, S. N.; Diefallah, El-H. M.; El-Fass, M. M.; Al-Sabban, E. A.

    Radiolysis of crystalline K 2Ni(C 2O 4) 2);6H 2O, K 2Ni(C 2O 4) 2 and Ni(C 2O 4));2H 2O has been investigated. The results showed that in K 2Ni(C 2O 4) 2);6H 2O, the initial G(Ni 3+) has a value of 3.75 and drops to about 1.27 when the dose approaches 1.2 × 10 22 eV g -1. The decrease in G(Ni 3+) with increasing radiation dose is accompanied with an increase in G(Ni 2+). In the irradiated anhydrated complex, the results however show an increase in G(Ni 3+) and a decrease in G(Ni 2+) with increasing radiation dose. The radiolysis of Ni(C 2O 4)·2H 2O showed an increase in G(Ni 3+) with increasing radiation dose. A mechanism has been suggested to explain the observed results.

  12. Electron-beam treatment of highly-coloured river water

    International Nuclear Information System (INIS)

    The possibility of the application of electron beam for the purification of highly-coloured (40-150 degrees) water was studied. The object of the study was water from the Segezha River (Karelia, Russia) used for the supply of a small town of the same name. It was found that irradiation of this water by electron beam to the dose of 1-3 kGy led to the decrease in its colour to 20 degrees and even less. The required dose depends on the season when the water was taken for irradiation; it is higher for autumn and (partially) spring seasons than for winter and (partially) summer periods. It was also found that irradiation considerably accelerates the sedimentation of suspended particles and ensures the necessary disinfection of the water together with the conservation and even the improvement of its other parameters. (Author)

  13. Ultrafast Pulse Radiolysis Using a Terawatt Laser Wakefield Accelerator

    CERN Document Server

    Oulianov, D A; Gosztola, D J; Korovyanko, O J; Rey de Castro, R C; Shkrob, I A; Crowell, Robert A.; Gosztola, David J.; Korovyanko, Oleg J.; Oulianov, Dmitri A.; Rey-de-Castro, Roberto C.; Shkrob, Ilya A.

    2006-01-01

    We report the first ultrafast pulse radiolysis transient absorption spectroscopy measurements from the Terawatt Ultrafast High Field Facility (TUHFF) at Argonne National Laboratory. TUHFF houses a 20 TW Ti:sapphire laser system that generates 2.5 nC sub-picosecond pulses of multi-MeV electrons at 10 Hz using laser wakefield acceleration. The system has been specifically optimized for kinetic measurements in a pump-probe fashion. This requires averaging over many shots which necessitates stable, reliable generation of electron pulses. The latter were used to generate excess electrons in pulse radiolysis of liquid water and concentrated solutions of perchloric acid. The hydronium ions in the acidic solutions react with the hydrated electrons resulting in the rapid decay of the transient absorbance at 800 nm on the picosecond time scale. Time resolution of a few picoseconds has been demonstrated. The current time resolution is determined primarily by the physical dimensions of the sample and the detection sensit...

  14. Radiolysis effects in sub-cooled nucleate boiling

    International Nuclear Information System (INIS)

    A hydrogen depleted region may form in the water during bubble formation when boiling occurs in a PWR. This would arise from stripping of gases into the steam phase. The depleted water may then become oxidising due to radiolysis forming H2O2. The presence of radiolytic oxidising conditions is one of the mechanisms proposed to explain deposits formed in Axial Offset Anomalies. This work describes a model that has been developed to examine this behaviour. The model deals with bubble growth and material transport as well as the radiolysis chemistry. The model simulates diffusion of species through the gas/liquid boundary layer. The appropriate mass conservation equations for this problem are described and the results of their numerical solution discussed. This model indicates the importance of the assumed boundary conditions on the results of the calculations. These boundary conditions are discussed in detail and the most appropriate ones for the actual reactor situation are outlined. The conclusion of this modelling study is that at normal PWR operating conditions of 40 cc H2 (STP) kg-1 it is unlikely that radiolysis in a subcooled boiling region would be important. The situation is more ambiguous at the 1 to 5 cc H2 (STP) kg-1 range. (author)

  15. Radiolysis effects in sub-cooled nucleate boiling

    Energy Technology Data Exchange (ETDEWEB)

    Dickinson, S.; Henshaw, J.; Tuson, A.; Sims, H.E. [AEA Technology (United Kingdom)

    2002-07-01

    A hydrogen depleted region may form in the water during bubble formation when boiling occurs in a PWR. This would arise from stripping of gases into the steam phase. The depleted water may then become oxidising due to radiolysis forming H{sub 2}O{sub 2}. The presence of radiolytic oxidising conditions is one of the mechanisms proposed to explain deposits formed in Axial Offset Anomalies. This work describes a model that has been developed to examine this behaviour. The model deals with bubble growth and material transport as well as the radiolysis chemistry. The model simulates diffusion of species through the gas/liquid boundary layer. The appropriate mass conservation equations for this problem are described and the results of their numerical solution discussed. This model indicates the importance of the assumed boundary conditions on the results of the calculations. These boundary conditions are discussed in detail and the most appropriate ones for the actual reactor situation are outlined. The conclusion of this modelling study is that at normal PWR operating conditions of 40 cc H{sub 2} (STP) kg{sup -1} it is unlikely that radiolysis in a subcooled boiling region would be important. The situation is more ambiguous at the 1 to 5 cc H{sub 2} (STP) kg{sup -1} range. (author)

  16. Investigation on the gas-phase radiolysis of metal complexes

    International Nuclear Information System (INIS)

    Gas-phase radiolysis of metal carbonyls has been performed. These carbonyls with iron, chromium and cobalt are sublimed easily by heating under atmospheric condition, and formed fine powder by gamma-ray-or electron-irradiation. Chemical compositions of fine powders prepared by electron beam irradiation are estimated as metal oxide after physical analysis such as microscopic observation, particle sizing, thermal and chemical analysis. These metal oxides thus obtained contain CO2, H2O, and some carbonic compounds, and they are removed easily by heating up to 400degC. (author)

  17. Absorbed Dose Distribution in a Pulse Radiolysis Optical Cell

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    When a liquid solution in an optical cell is irradiated by an intense pulsed electron beam, it may be important in the chemical analysis of the solution to know the distribution of energy deposited throughout the cell. For the present work, absorbed dose distributions were measured by thin...... radiochromic dye film dosimeters placed at various depths in a quartz glass pulse radiolysis cell. The cell was irradiated with 30 ns pulses from a field-emission electron accelerator having a broad spectrum with a maximum energy of ≈MeV. The measured three-dimensional dose distributions showed sharp gradients...

  18. Tractor beam on the water surface

    CERN Document Server

    Punzmann, Horst; Xia, Hua; Falkovich, Gregory; Shats, Michael

    2014-01-01

    Can one send a wave to bring an object from a distance? The general idea is inspired by the recent success in moving micro particles using light and the development of a tractor beam concept. For fluid surfaces, however, the only known paradigm is the Stokes drift model, where linear planar waves push particles in the direction of the wave propagation. Here we show how to fetch a macroscopic floater from a large distance by sending a surface wave towards it. We develop a new method of remote manipulation of floaters by forming inward and outward surface jets, stationary vortices, and other complex surface flows using nonlinear waves generated by a vertically oscillating plunger. The flows can be engineered by changing the geometry and the power of a wave maker, and the flow dissipation. The new method is robust and works both for long gravity and for short capillary waves. We use a novel method of visualising 3D particle trajectories on the surface. This letter introduces a new conceptual framework for unders...

  19. Radiolysis of polychlorodibenzodioxins in hexane

    International Nuclear Information System (INIS)

    Possible decomposition of polychlorodibenzodioxins (PCDD) in hexane under gamma-radiation effect is studied. 2,3,7,8-Tetrachlorodibenzodioxin (2,3,7,8-TCDD) solution in hexane was irradiated by 1.0, 3.8 and 6.5 Mrad. It is stated that 2,3,7,8-TCDD radiolysis (by 6.5 Mrad dose) its decomposition degree according to mass-spectrometry data is not less than 99.99995 rel.% (detection limit is 2 x 10-10 mass.%). Therewith, less chlorinated dibenzodioxin forming under lower radiation doses, are not detected. Promising use of gamma-radiation for complete decomposition of PCDD in wastes of chemical and petro-chemical industries is shown

  20. Radiolysis of hexane absorbing on borosilicate surface research

    International Nuclear Information System (INIS)

    The radiolysis process of hexane absorbing on borosilicate with various hydration degree is being investigated. Samples of borosilicate were treated by thermal vacuum at and T=493 K and P=1.33·10-4 Pa. The absorption of water and hexane was carried out on manometric equipment at 77 K temperature. An irradiation was conducted by γ-rays from 60Co source in the sealed in ampoules at 77 K with 10 kGy dose. In the irradiated samples the ESR spectrum with wide range that is characteristic for irradiated alkanes in the absorbing condition was observed. With increase of temperature of registration narrowing lines and improved sanction connected to recombination processes of radicals was observed. With increase of a hydration of a surface the redistribution and reduction of intensity separate component of a spectrum was observed. It specifies formation and stabilization bonding of radicals at smaller filling of a surface borosilicate. To reveal structure of radiolysis products IR spectra of desorbed from a borosilicate surface gas products were received at 333 K. In the field of low-frequency deformation of fluctuations CH2-groups the doublet strip with maxima was observed at 790 cm-1 and 770 cm-1 which is referred to low-molecular of radiolysis products

  1. Pulse radiolysis studies of model membranes

    International Nuclear Information System (INIS)

    In this thesis the influence of the structure of membranes on the processes in cell membranes were examined. Different models of the membranes were evaluated. Pulse radiolysis was used as the technique to examine the membranes. (R.B.)

  2. Pulse radiolysis facilities and activities in Japan

    International Nuclear Information System (INIS)

    Pulse radiolysis studies in Japan have been reviewed in special reference to the facilities and the people who have engaged in the experiments. Main achievement is summarized with the list of selected publications. (author)

  3. Study by γ radiolysis and pulsed radiolysis of the reactivity of the superoxide ion in the oxyhemoglobin-methemoglobin system

    International Nuclear Information System (INIS)

    γ radiolysis of aqueous solutions of methemoglobin (MetHb) in the presence of formate ions, shows that only 25% of the total protein is reduced in oxyhemoglobin (HbO2) by superoxide ions O2- according to the reaction MetHb+O2-→HbO2. The result can be attributed neither to the reactions of O2- with HbO2, nor the oxidation of HbO2 by H2O2 produced in the radiolysis of water and by dismutation of O2-. Pulse radiolysis studies of this reaction strongly suggest the formation of a transient complex 'MetHbO2-' during the reaction. In addition to the well known self-oxidation of HbO2, these results show the existence of an equilibrium between HbO2 and MetHb+O2-. Such an equilibrium could give rise, 'in vivo' to a nearly steady concentration of superoxide ions which could initiate a reaction favoring oxidation by oxygen

  4. Stability of methyl p-hydroxybenzoate (methylparaben) to gamma radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Angelini, Giancarlo; Bucci, Roberto; Colosimo, Marcello; Margonelli, Andrea

    1998-01-01

    The stability of methyl p-hydroxybenzoate during {sup 60}Co {gamma}-radiolysis was studied in the solid state and in 10 {mu}M water solution. The work was undertaken as a model to be extended to radiolytic sterilization of pharmaceutical preparations. Only in water moderate decomposition was observed at high doses (50 KGy, whilst at 5 kGy sterilization was verified. Methylparaben labelled with carbon-14 on the carboxyl group provided the decomposition yield by the reverse isotope dilution method; mass balances were drawn and mechanisms suggested.

  5. Stability of methyl p-hydroxybenzoate (methylparaben) to gamma radiolysis

    Science.gov (United States)

    Angelini, Giancarlo; Bucci, Roberto; Colosimo, Marcello; Margonelli, Andrea

    1998-01-01

    The stability of methyl p-hydroxybenzoate during 60Co γ-radiolysis was studied in the solid state and in 10 μM water solution. The work was undertaken as a model to be extended to radiolytic sterilization of pharmaceutical preparations. Only in water moderate decomposition was observed at high doses (50 KGy, whilst at 5 kGy sterilization was verified. Methylparaben labelled with carbon-14 on the carboxyl group provided the decomposition yield by the reverse isotope dilution method; mass balances were drawn and mechanisms suggested.

  6. Stability of methyl p-hydroxybenzoate (methylparaben) to gamma radiolysis

    International Nuclear Information System (INIS)

    The stability of methyl p-hydroxybenzoate during 60Co γ-radiolysis was studied in the solid state and in 10 μM water solution. The work was undertaken as a model to be extended to radiolytic sterilization of pharmaceutical preparations. Only in water moderate decomposition was observed at high doses (50 KGy, whilst at 5 kGy sterilization was verified. Methylparaben labelled with carbon-14 on the carboxyl group provided the decomposition yield by the reverse isotope dilution method; mass balances were drawn and mechanisms suggested

  7. Electron beam destruction of contaminant gasoline additives in water

    International Nuclear Information System (INIS)

    The U.S. phase-out of tetraethyl lead in the 1970's resulted in ever-increasing amounts of high-octane compounds, notably methyl tert-butyl ether (MTBE), being added to gasoline to give cleaner burning fuel. However, the 1990 Clean Air Act oxygenate requirements led refiners to more than double the amount of these chemicals being blended into gasoline, and this combination of large scale use, high water solubility, low soil adsorption, and only minor biodegradability under normal aquifer conditions has now resulted in large-scale MTBE contamination occurring in natural, ground, and drinking water systems. The remediation of gasoline oxygenate contaminated ground and drinking water remains a pressing environmental problem. Studies of MTBE-contaminated water have shown that conventional air stripping and carbon adsorption are not viable technologies. Therefore Advanced Oxidation (and Reduction) Processes (AOPs) are expected to be required for these remediations. These technologies are defined as those that use the hydroxyl radical (and hydrated electron) and include H2O2 /UV, H2O2 /Fe(II), H2O2/O3 , TiO2/UV, sonolysis, and electron beam treatment of contaminated waters. The water decontamination of current and potential gasoline oxygenates (MTBE, ethyl tert-butyl ether (ETBE), tert-butyl alcohol (TBA), ethanol, and tert-amyl ether (TAME)) using free radicals produced by the electron beam irradiation AOP has been studied. Kinetic studies have been used to determine rate constants for the reaction of these ethers and alcohols with hydroxyl radicals, hydrated electrons and hydrogen atoms, and also the subsequent formation and decay of their corresponding peroxyl radicals. These kinetic data have been combined with mechanistic degradation and product distribution information to construct a computer kinetic model that can predict the removal of these contaminants under a variety of water conditions. This model was used to compare the predicted MTBE removal from water

  8. Valine radiolysis by MeV ions

    Science.gov (United States)

    Da Silveira, Enio

    2016-07-01

    Valine, (CH3)2 CHCH (NH2) COOH, is a protein amino acid that has been identified in extraterrestrial environments and in the Murchison meteorite [1]. The knowledge of half-lives of small organic molecules under ionizing radiation is important for the setup of models describing the spread out of prebiotics across the Solar System or the Galaxy. We have investigated typical effects of MeV cosmic ray ions on prebiotic molecules in laboratory by impinging ions produced by the PUC-Rio Van de Graaff accelerator. Pure valine films, deposited by evaporation on KBr substrates, were irradiated by H ^{+}, He ^{+} and N ^{+} ion beams, from 0.5 to 1.5 MeV and up to a fluence of 10 ^{15} projectiles/cm ^{2}. The sample temperature was varied from 10 K to 300 K. The irradiation was interrupted several times for Mid-FTIR analysis of the sample. The main findings are: 1- The column density of the valine decreases exponentially with fluence. 2- In some cases, a second exponential appears in the beginning of irradiation; this feature has been attributed to sample compaction by the ion beam [2]. 3- Destruction cross sections of valine are in the 10 ^{-15} cm ^{2} range, while compaction cross sections are in the 10 ^{-14} cm ^{2} range. 4- Destruction cross section increases with the stopping power of the beam and also with the sample temperature. 5- Surprisingly, during the radiolysis of valine, just CO _{2} is seen by as a daughter molecule formed in the bulk. 6- After long beam fluence, also a CO peak appears in the infrared spectrum; this species is however interpreted as a fragment of the formed CO2 molecules. 7- Considering the flux ratio between laboratory experiments and actual galactic cosmic rays, half-life of valine is predicted for ISM conditions [3]. This work on pure valine is the first measurement of a series. New experiments are planned for determining cross sections of valine dissolved in H _{2}O or CO _{2}, inspired by the study performed for glycine [4]. [1] P

  9. Assessment of the combined effects of temperature increase, water convection, migration of radionuclides, and radiolysis on the safety of nuclear waste repository in the Boom clay

    International Nuclear Information System (INIS)

    For a potential repository in the Boom clay formation at 220 m beneath the nuclear research center at Mol, Belgium, extensive temperature calculations have been done for several repository configurations. Taking into account, near field and far field temperature limitations, an acceptable heat load of 2.5 w/m2, and a cooling time of 50 years prior to disposal, have been derived. Hydrological phenomena in the water tables surrounding the Boom clay layer have been studied by installing a piezometric observation network over a surface of 2500 km2. A mathematical model has been developed to tern and the water transfer through the low impermeability clay layer. Verification of these results has been attempted by dating of the groundwaters and the interstitial clay water. A unidirectional analytical model has been developed that takes into account radioactive decay and water convection by a pressure gradient and assumes concentration equilibrium between the mobile and the stagnant fraction of the liquid phase

  10. A study on the emulsification property of the γ radiolysis of TOPO

    International Nuclear Information System (INIS)

    Trioctyl phosphine oxide (TOPO) was used as the model of TRPO and its γ radiolysis was studied. The irradiated samples were dissolved in cyclohexane (CH), then extracted with 5% Na2CO3 and subsequently extracted with distilled water. Emulsification appeared in the process of water extraction. The extent of emulsification depended on the dose absorbed and pH of the system. It increased with the increasing of the dose absorbed, but the total G value decreased. The structures of radiolysis products were identified by IR spectra, UV spectra and element analysis. The results demonstrated that it was the oligomer of TOPO, phosphinic acid and its ester that induced emulsification

  11. Radiolysis of some aqueous solutions of neutron absorbers

    International Nuclear Information System (INIS)

    The initial yield of molecular hydrogen formed by radiolytic decomposition of water in reactor and 60Co gamma radiation is decreased by the presence of salts of polyvalent elements possessing only one stable valence, i.e cadmium, zinc, magnesium, gadolinium. This effect is favourable for the use of cadmium and gadolinium as soluble neutron absorber in heavy water reactors. Cations of these salts are not inert toward the primary products of water radiolysis. They have a high degree of reactivity toward the hydrated electron, which is the precursor of molecular hydrogen in neutral or alkaline aqueous media. The value of the rate constant for the reaction between cadmium ion and hydrated electron was shown to be (6.1 ± 1.8) 1010 M-1 s-1. Boric acid at low concentration has no effect on the radiation chemistry of water. An isotope effect has been found in the radiolysis of heavy water, corresponding to a lowering of initial yield [G0(D2) 0(H2)]. additionally it was necessary to determine the influence of organic impurities, remaining after the purification of water, on the mechanism of its radiolytic decomposition. (author)

  12. Some evidence of radiolysis in a uranium ore body -- Quantification and interpretation

    International Nuclear Information System (INIS)

    Locally oxidizing conditions in the near-field of the Cigar Lake uranium deposit was observed. Ongoing processes of water radiolysis has also been predicted previously by the mass transport model. In the ore there was an enhanced concentration of helium, hydrogen and sulfate. Sulfate is the only oxidizing species of substantial amount in the groundwater samples, and is possibly indirectly produced by water radiolysis and oxidation of sulfides. The ongoing oxidant production rate has been calculated by the mass transport model. In this paper, the issue of water radiolysis is addressed from a more fundamental angle of approach. The maximum oxidant production rate is calculated based on the assumptions of geometric dispersion of the ore constituents, the estimate of the total radiation energy, the fraction of energy deposited into the pore water, and the G-values of water. The results show that only a few percent of the total radiation energy is deposited into the pore water to cause water radiolysis. If the recombination factor projected by other researchers are accounted for, the oxidant production rate thus calculated agrees with the present-day ongoing oxidant production rate predicted by the mass transport model

  13. Radiolysis of iodine in moist air

    International Nuclear Information System (INIS)

    The gas phase radiolysis of moist air, with small additions of methane and molecular iodine, has been modelled in an attempt to judge the effects of radiation fields on the chemistry of the gas phase in the containment space after a nuclear accident. The model does not allow for any interchange of species between the gas phase and liquid water, as would be the case in a real accident. Use of the currently accepted rate constants makes it clear that methyl iodide cannot be formed by abstraction of iodine atoms from I2 by methyl radicals, as sometimes assumed. The oxygen present in the air competes far too efficiently for the methyl radicals. Thus, the observed methyl iodide yields must arise in other ways. Iodine molecules were converted into oxygenated species such as IO2 and I2O3 during the first two minutes after an accident, assuming a dose rate of 2.2 x 1015 eV·dm-3·s-1. The main route for oxidation is the reaction of hydroxyl radicals with iodine molecules. This reaction has been shown to be fast, at least in the gas phase. The oxygenated iodine species are presumably converted into soluble species such as I4O9, but not enough rate constants are available to model this conversion successfully. Modelling was done with the computer program, MAKSIMA-CHEMIST. 32 refs

  14. Radiolysis of aqueous-ethanolic solution of tryptophan

    International Nuclear Information System (INIS)

    The effect of ethanol on radiation stability of tryptophan during γ-irradiation of its aqueous solutions was investigated. In comparison with radiation losses of tryptophan irradiated in pure water, the losses in aqueous-ethanolic solutions are considerably higher and they increase with increasing ethanol concentration. Basic radiation products of tryptophan formed on irradiation of its aqueous-ethanolic solutions in consequence of the reaction of tryptophan with acetaldehyde as the main product of radiolysis of ethanol were followed by paper electrophoresis. (author)

  15. Direct absorbed dose to water determination based on water calorimetry in scanning proton beam delivery

    International Nuclear Information System (INIS)

    Purpose: The aim of this manuscript is to describe the direct measurement of absolute absorbed dose to water in a scanned proton radiotherapy beam using a water calorimeter primary standard. Methods: The McGill water calorimeter, which has been validated in photon and electron beams as well as in HDR 192Ir brachytherapy, was used to measure the absorbed dose to water in double scattering and scanning proton irradiations. The measurements were made at the Massachusetts General Hospital proton radiotherapy facility. The correction factors in water calorimetry were numerically calculated and various parameters affecting their magnitude and uncertainty were studied. The absorbed dose to water was compared to that obtained using an Exradin T1 Chamber based on the IAEA TRS-398 protocol. Results: The overall 1-sigma uncertainty on absorbed dose to water amounts to 0.4% and 0.6% in scattered and scanned proton water calorimetry, respectively. This compares to an overall uncertainty of 1.9% for currently accepted IAEA TRS-398 reference absorbed dose measurement protocol. The absorbed dose from water calorimetry agrees with the results from TRS-398 well to within 1-sigma uncertainty. Conclusions: This work demonstrates that a primary absorbed dose standard based on water calorimetry is feasible in scattered and scanned proton beams.

  16. Calculated LET spectrum from antiproton beams stopping in water

    CERN Document Server

    Bassler, Niels

    2009-01-01

    Antiprotons have been proposed as a potential modality for radiotherapy because the annihilation at the end of range leads to roughly a doubling of physical dose in the Bragg peak region. So far it has been anticipated that the radiobiology of antiproton beams is similar to that of protons in the entry region of the beam, but very different in the annihilation region, due to the expected high-LET components resulting from the annihilation. On closer inspection we find that calculations of dose averaged LET in the entry region may suggest that the RBE of antiprotons in the plateau region could significantly differ from unity, which seems to warrant closer inspection of the radiobiology in this region. Materials and Methods. Monte Carlo simulations using FLUKA were performed for calculating the entire particle spectrum of a beam of 126 MeV antiprotons hitting a water phantom. Results and Discussion. In the plateau region of the simulated antiproton beam we observe a dose-averaged unrestrict...

  17. Study of the gamma radiolysis mechanisms of PVC (poly vinyl chloride)

    International Nuclear Information System (INIS)

    The works presented in this memory enter in the context of the management of plastic nuclear waste. This study was carried out on pure PVC and industrial PVC (formulated polymer). The aim of this work is to study and identify the radiolysis products (radicals, gases, oxidation products), the changes of the physico-chemical properties of the material (in particular reticulation and scission), but the leachable products too (radiolysis products or additives contained in the industrial PVC) able to have complexing properties and apt to contribute to the migration of radioelements outside after saturation in water of the storage site. The obtained results are detailed. (O.M.)

  18. Degradation of naphthalene and fluorene by radiolysis using accelerated electrons

    International Nuclear Information System (INIS)

    The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

  19. Water equivalence of some plastic-water phantom materials for clinical proton beam dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Al-Sulaiti, L., E-mail: l.al-sulaiti@surrey.ac.uk [Physics Department, University of Surrey, Guildford (United Kingdom); Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom); Shipley, D.; Thomas, R. [Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom); Owen, P. [Physics Department, University of Surrey, Guildford (United Kingdom); Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom); Kacperek, A. [Douglas Cyclotron, Clatterbridge Centre for Oncology, Wirral (United Kingdom); Regan, P.H. [Physics Department, University of Surrey, Guildford (United Kingdom); Palmans, H. [Radiation Dosimetry Team, National Physical Laboratory, Teddington (United Kingdom)

    2012-07-15

    Plastic-water phantom materials are not exactly water equivalent since they have a different elemental composition and different interaction cross sections for protons than water. Several studies of the water equivalence of plastic-water phantom materials have been reported for photon and electron beams, but none for clinical proton beams. In proton beams, the difference between non-elastic nuclear interactions in plastic-water phantom materials compared to those in water should be considered. In this work, the water equivalence of Plastic Water{sup Registered-Sign} (PW){sup 1}, Plastic Water{sup Registered-Sign} Diagnostic Therapy (PWDT){sup 1} and solid water (WT1){sup 2} phantoms was studied for clinical proton energies of 60 MeV and 200 MeV. This was done by evaluating the fluence correction factor at equivalent depths; first with respect to water and then with respect to graphite by experiment and Monte Carlo (MC) simulations using FLUKA. MC simulations showed that the fluence correction with respect to water was less than 0.5% up to the entire penetration depth of the protons at 60 MeV and less than 1% at 200 MeV up to 20 cm depth for PWDT, PW and WT1. With respect to graphite the fluence correction was about 0.5% for 60 MeV and about 4% for 200 MeV. The experimental results for modulated and un-modulated 60 MeV proton beams showed good agreement with the MC simulated fluence correction factors with respect to graphite deviating less than 1% from unity for the three plastic-water phantoms. - Highlights: Black-Right-Pointing-Pointer We study plastic-water in clinical proton beams by experiment and Monte Carlo. Black-Right-Pointing-Pointer We obtain fluence correction factors for water and graphite. Black-Right-Pointing-Pointer The correction factor for water was close to 1 at 60 MeV and <0.990 at 200 MeV. Black-Right-Pointing-Pointer The correction factor for graphite was {approx}0.5% at 60 MeV and up to 4% at 200 MeV.

  20. Radiolysis of Aqueous Benzene Solutions

    International Nuclear Information System (INIS)

    Aerated and deaerated aqueous solutions of benzene have been irradiated with 60Co γ-rays. The products of radiolysis in deaerated, unbuffered or acid, solutions were phenol, biphenyl, hydrogen and in acid solutions also hydrogen peroxide with the following yields: G(phenol) = 0. 37 (0. 37), G(biphenyl) = 1.3 (1.7), G(H2) = 0.44 (0. 43) and G(H2O2) = 0 (0.60), the figures in brackets giving the results for acid solutions. The results are shown to agree with the conclusion that k(e-aq + H2O2) >> k(H + H2O2). Furthermore, the results indicate that a competition takes place between the reactions: 2 C6H6OH · -> dimer -> biphenyl. C6H7 · + C6H6OH · -> dimer -> biphenyl. The yields in aerated, unbuffered or acid, solutions were: G(phenol) = 2.1 (2.3), G(biphenyl) = 0 (0), and G(H2O2) = 2.2 (3.1), the figures in brackets being valid for acid solutions. The ratio k(H + C6H6)/k(H + O2) was 1.4x10-2. The results indicate that peroxides, or more probably hydroperoxides, take part in the reactions. After the addition of Fe2+ or Fe3+ to aerated acid solutions G(phenol) was increased to 6.6 and 3.4 respectively. Oxygen was consumed more rapidly in the presence of Fe. Reaction mechanisms are discussed

  1. Effect of electron beam irradiation on fisheries water

    International Nuclear Information System (INIS)

    This paper studies about water obtained from fish pond of fisheries research centre. Usual water quality parameters such as pH, COD, Turbidity and Ammonia content were analyzed before and after irradiation. Electron beam irradiation was used to irradiate the water with the dose 100 kGy, 200 kGy and 300 kGy. Only high dose was applied on this water as only a limited amount of samples was supplied. All the parameters indicated a slight increase after irradiation except for the ammonia content, which showed a gradual decrease as irradiation dose increases. Sample condition was changed before irradiation in order to obtain more effective results in the following batch. The water sample from fisheries was diluted with distilled water to the ratio of 1:1.This was followed with irradiation at 100 kGy, 200 kGy and 300 kGy. The results still showed an increase in all parameters after irradiation except for ammonia content. For the following irradiation batch, the pH of the sample was adjusted to pH 4 and pH 8 before irradiation. For this sample the irradiation dose selected was only 100 kGy. A higher value of ammonia was observed for the sample with pH 4 after irradiation. Other parameters were almost the same as the first two batches. (author)

  2. A microsecond pulse radiolysis system in Beijing

    International Nuclear Information System (INIS)

    The first setup of pulse radiolysis system in China with the time resolution of 2 microseconds has been built up recently in Beijing Radiation Center. The experimental apparatus is described briefly. The observation of transient absorption of Br2- and I2- radicals in aqueous solution using this system is introduced. (author)

  3. A microsecond pulse radiolysis system in Beijing

    Energy Technology Data Exchange (ETDEWEB)

    Andong Liu; Zhongwei Zhao; Zhongliang Tong; Yingxin Sun; Hongchun Gu; Wanhua Shun; Huadan Hu; Zhonghe Hao; Ruiying Zhou (Beijing Normal Univ., BJ (China). Inst. of Low Energy Nuclear Physics)

    1989-01-01

    The first setup of pulse radiolysis system in China with the time resolution of 2 microseconds has been built up recently in Beijing Radiation Center. The experimental apparatus is described briefly. The observation of transient absorption of Br{sub 2}{sup -} and I{sub 2}{sup -} radicals in aqueous solution using this system is introduced. (author).

  4. Application of chemsimul for groundwater radiolysis

    DEFF Research Database (Denmark)

    Christensen, Hilbert; Bjergbakke, Erling

    1986-01-01

    The application of the radiation chemical computer program chemsimul, for the calculation of radiolysis in connection with the storage of high level waste has been studied. Methods have been developed for the diffusion of gases out of the irradiated system, for the continuous addition of Fe2+ to ...

  5. Pulse radiolysis apparatus for monitoring at 2000 Å

    DEFF Research Database (Denmark)

    Christensen, H.C.; Nilsson, G.; Pagsberg, Palle Bjørn; Nielsen, Sigurd O.

    1969-01-01

    increased luminance; (2) a fast electronic switch that cut out the signal due to the Cerenkov radiation; (3) a secondary emission chamber that allowed the simultaneous measurement of the current and the direction of the pulsed electron beam; and (4) a system for remote controlled change of liquid samples......A pulse radiolysis apparatus with photometric monitoring has been built around an 11 MeV, 250 mA peak current, linac that delivers single 0.25 to 4 μsec pulses. The novel features of the apparatus include (1) a 450 W xenon lamp as the analyzing light source which in pulsed operation had a 25 times...... stored in glass syringes. Reliable measurements of optical transmission could be made starting 0.2 μsec after the electron pulse at wavelengths down to 2000 Å on transient species having products of yield and absorptivity G×ε>500 mole (100 eV)-1.liter-1.cm-1...

  6. Improvements in time resolution and signal-to-noise ratio in a compact pico-second pulse radiolysis system

    International Nuclear Information System (INIS)

    A compact pico-second pulse radiolysis system has been developing at Waseda University for studying primary processes in radiation chemistry. The system is composed of a photo-injector system and a pico-second all-solid-state laser system. An infrared (IR) and an ultraviolet (UV) laser pulses are obtained from mode-locked Nd:YLF laser system and used for generation of the white light continuum as a probe light and the irradiation to the Cu cathode of a photo-cathode RF-gun, respectively. To improve signal-to-noise (S/N) ratio and time resolution of this pulse radiolysis system, we optimized both probe light and pump electron beam. As a result, our pico-second pulse radiolysis system has been enough to study the primary processes of radiation chemistry. The experimental results and the improvements of our system are described in this paper

  7. AISI 316L under electron radiolysis at high temperature and pressure in PWR modelling conditions

    International Nuclear Information System (INIS)

    temperature (HT), 280-320 deg. C, and high pressure (HP), 15.5 MPa. Very few data are available in the literature on the role of HTHP water radiolysis on the corrosion of metallic reactor components. The present approach use electron beam to control the production of radiolytic species at a AISI 316L/PWR solution interface in a high temperature and high pressure (HTHP) electrochemical cell working at the range [25 deg. C, 1 bar] - [300 deg. C, 90 bar]. The cell is designed to record the free corrosion potential of the AISI 316L/PWR solution interface mounted on line at the SIRIUS pelletron delivering the electron beam (LSI, Ecole Polytechnique, France). The PWR primary solutions are simulated by aqueous solutions prepared at room temperature by adding boric acid and lithium hydroxide to high purity water and, in some cases, purged with Ar/H2 flow. At the AISI 316L/PWR solution interfaces irradiated between 25 deg. C/ 1 bar and 300 deg. C/ 90 bar, electrons emerge at ∼0.6 MeV and the flux varies from ∼1010 to 1012 e-.cm-2.s-1. The results clearly show that the response of the free potential between the AISI316L/water interface and a pseudo-reference electrode, i.e. a platinum wire during the irradiation (from electron beam switch-on until cut-off) depends on many parameters: the energy of the electron beam, the temperature and pressure, the concentration of hydrogen in the solution, the ageing of the disc electrode, the growth conditions of the initial oxide passive layers, etc... These results can be compared with those which have obtained by using the proton beam (CEMHTI, CNRS Orleans, France). Surface characterization experiments (XPS, SEM, Raman spectroscopy, photoluminescence...) on the oxide layer of AISI316L which are formed under the irradiation could also bring new information about the irradiation influence on the AISI316L. (authors)

  8. Picosecond pulse radiolysis study of primary reactions in solutions

    International Nuclear Information System (INIS)

    Following the discovery of ionizing radiations and their chemical effects, it was important to study and comprehend the formation mechanisms of short lived free radicals and molecular products. In order to perform such studies, researchers and research groups worked on developing tools allowing both formation and detection of those species at short time scales. Nowadays, pulse radiolysis imposed itself as a fundamental and efficient tool allowing scientists to probe chemical effects as well as reaction mechanisms in studied media. The Laboratoire de Chimie Physique d'Orsay 'LCP' is an interdisciplinary laboratory hosting the platform of fast kinetics known as 'ELYSE'. Due to its femtosecond laser and its picosecond electron accelerator, we have the possibility to study chemical effects of ionizing radiations interaction with media at ultrashort times up to ∼5 ps.Knowing that we are interested in primary reactions induced in aqueous media by ionizing radiations, ELYSE represents the essential tool in performing our studies. The obtained results concern:- First direct determination of hydroxyl radical 'HO*' radiolytic yield as function of time at picosecond time scale;- Direct effect of ionizing radiation in highly concentrated aqueous solutions as well as investigation of the ultrafast electron transfer reaction between solute molecules and positive holes 'H2O*+' formed upon water radiolysis;- Study at room temperature of electron transfer reaction between solvated electron (electron donor) and organic solutes (electron acceptors) en viscous medium;- Study at room temperature of electron's solvation dynamics in ethylene glycol and 2-propanol. (author)

  9. Development of nanosecond time-resolved infrared detection at the LEAF pulse radiolysis facility

    Energy Technology Data Exchange (ETDEWEB)

    Grills, David C., E-mail: dcgrills@bnl.gov; Farrington, Jaime A.; Layne, Bobby H.; Preses, Jack M.; Wishart, James F. [Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000 (United States); Bernstein, Herbert J. [Department of Mathematics and Computer Science, Dowling College, 1300 William Floyd Parkway, Shirley, New York 11967 (United States)

    2015-04-15

    When coupled with transient absorption spectroscopy, pulse radiolysis, which utilizes high-energy electron pulses from an accelerator, is a powerful tool for investigating the kinetics and thermodynamics of a wide range of radiation-induced redox and electron transfer processes. The majority of these investigations detect transient species in the UV, visible, or near-IR spectral regions. Unfortunately, the often-broad and featureless absorption bands in these regions can make the definitive identification of intermediates difficult. Time-resolved vibrational spectroscopy would offer much improved structural characterization, but has received only limited application in pulse radiolysis. In this paper, we describe in detail the development of a unique nanosecond time-resolved infrared (TRIR) detection capability for condensed-phase pulse radiolysis on a new beam line at the LEAF facility of Brookhaven National Laboratory. The system makes use of a suite of high-power, continuous wave external-cavity quantum cascade lasers as the IR probe source, with coverage from 2330 to 1051 cm{sup −1}. The response time of the TRIR detection setup is ∼40 ns, with a typical sensitivity of ∼100 μOD after 4-8 signal averages using a dual-beam probe/reference normalization detection scheme. This new detection method has enabled mechanistic investigations of a range of radiation-induced chemical processes, some of which are highlighted here.

  10. The reactivity of the electron formed in the radiolysis of aerated alkaline aqueous solutions containing tetracycline hydrochloride, at 77 Ksup(+)

    International Nuclear Information System (INIS)

    The radiolysis of tetracycline hydrochloride dissolved in aerated alkaline aqueous solutions containing 0.1, 0.5 and 1M NaOH at 77 K, followed by ESR is reported. The rate constants for the reactions between the electron and physical or chemical traps which are present in these solutions are calculated. The reactivity of electrons that are formed in the radiolysis of water decreases in the following proportions: physical traps: chemical traps: molecules of water (4.8x10sup(14) : 6.5x10sup(8) : 1.0). The electrons react preferentially with the solute instead of the solvent. (author)

  11. Gamma Ray Radiolysis of the FPEX Solvent

    International Nuclear Information System (INIS)

    Slide presentation. FPEX contains a calixarene for Cs extraction, a crown ether for Sr extraction, Cs7SB modifier, and TOA to aid in stripping, in Isopar L diluent. The radiation stability FPEX must be evaluated prior to process use. Radiolytic degradation of species in solution are due to reaction with the direct radiolysis products of the diluent. In Isopar L, the reactive species produced include e-, ·H and alkane radicals, resulting in a reducing environment. However, in nitric acid, oxidizing hydroxyl (·OH) and nitro (·NO2) radicals dominate system chemistry. Thus, the nature of diluent and the presence of radical scavengers affect the results of irradiation. We report the preliminary results of a new program to investigate the radiolysis of FPEX using the 60Co irradiation of FPEX neat solvent, acid pre-equilibrated solvent and mixed aerated phases. The Cs and Sr distribution ratios were used as metrics

  12. Structural analysis of radiolysis products of sennoside

    Energy Technology Data Exchange (ETDEWEB)

    Song, Hyun Pa; Kim, Dong Ho [KAERI, Daejeon (Korea, Republic of)

    2011-01-15

    The purpose of the present investigation was to analyze the structural changes of gamma irradiated sennoside B (prodrug) and to provide the possibility for application of irradiation to induce structural changes of the prodrugs for enhanced bioavailability. Sennoside B (200 ppm) in 70% methanol solution with or without the use of hydrogen peroxide or nitrous oxide gas was irradiated with 1, 3, 5, 10 and 20 kGy by gamma ray. The radiolysis products of gamma irradiated sennoside B solution were identified and determined by TLC, HPLC and LC-MS/MS. The sennoside B quantity decreased when irradiation dose increased and completely degraded at 10 kGy of irradiation. There was a linear relationship between the production of the radiolysis compounds and the absorbed dose of the gamma ray irradiated sennoside B. Radiolysis products yields increased on the addition of nitrous oxide gas into the sennoside B solution. No anthraquinone compounds were formed after irradiation of sennosie B. Scission of the O-glycoside bond and consequently formation of aglycone of sennoside B was observed

  13. Structural analysis of radiolysis products of sennoside

    International Nuclear Information System (INIS)

    The purpose of the present investigation was to analyze the structural changes of gamma irradiated sennoside B (prodrug) and to provide the possibility for application of irradiation to induce structural changes of the prodrugs for enhanced bioavailability. Sennoside B (200 ppm) in 70% methanol solution with or without the use of hydrogen peroxide or nitrous oxide gas was irradiated with 1, 3, 5, 10 and 20 kGy by gamma ray. The radiolysis products of gamma irradiated sennoside B solution were identified and determined by TLC, HPLC and LC-MS/MS. The sennoside B quantity decreased when irradiation dose increased and completely degraded at 10 kGy of irradiation. There was a linear relationship between the production of the radiolysis compounds and the absorbed dose of the gamma ray irradiated sennoside B. Radiolysis products yields increased on the addition of nitrous oxide gas into the sennoside B solution. No anthraquinone compounds were formed after irradiation of sennosie B. Scission of the O-glycoside bond and consequently formation of aglycone of sennoside B was observed

  14. Radiolysis of HCN in heterogeneous phase

    International Nuclear Information System (INIS)

    HCN is considered to have been one of the more important precursors of biomolecules leading to the origin of life in the early Earth. This simple molecule is a key compound in chemical evolution studies. HCN could have been formed by a number of routes under possible prebiological conditions, and it is likely that this compound may be present in prebiotic environments because it is formed by a variety of processes driven by thermal energy. In this work an attempt is made to analyze the formation of some carboxylic acids from simple CN-compounds. As a source of energy we have employed ionizing radiation. The role of ionizing radiation has been underestimated in prebiotic chemistry. However, our previous work has demonstrated that a great variety of organic compounds important to life are formed by the irradiation of aqueous solution of HCN. We study the behavior of HCN molecule in an heterogeneous phase. With this purpose we have analyzed the effect of a clay mineral, namely Na-montmorillonite, in the radiolysis of aqueous solutions of HCN. The results obtained shows that carboxylic acids are formed among the radiolysis product of HCN. Their production is a function of radiation dose. In the radiolysis of HCN in the presence of clay, the formation of carboxylic acids is observed but in less extent. (author)

  15. Radiolysis of a pig gastric glycopeptide

    International Nuclear Information System (INIS)

    A study has been made of the radiolysis of a single purified preparation of pig gastric glycopeptide F1, since the radiosensitivity of the epithelial lining of the digestive tract is of special interest. The amino acid composition of this glycopeptide is similar to the pattern found in several glycoproteins from mucous secretions. Steady-state 60Co gamma irradiations were carried out on aqueous glycoprotein solutions (1 mg/ml). Measurements were made of viscosity, and elution patterns on gel filtration on Sephadex G-200, and chromatographic analyses carried out for hexoses, fucose and amino acids. Transient absorption spectra after pulse radiolysis using a 12 meV linear accelerator gave information on the initial reactions between the primary aqueous free radicals and the glycopeptide. The results indicated that very low radiation doses (5x102 rad) could produce some depolymerisation of the glycopeptide, which increased at higher doses (104 and 105 rad). At the highest dose (105 rad) some evident modification of the carbo-hydrate components took place, whereas the peptide moiety seemed unaffected by irradiation. The pulse-radiolysis data also indicated that the transient absorbance was due to the carbohydrate moiety. These results suggest that the glucide moiety can exert some radio-protective action at the level of the protein core, the highest depolymerisation being associated with damage to the carbohydrate components. (U.K.)

  16. The radiolysis of lithium oxide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Tiliks, J.; Supe, A.; Kizane, G.; Tiliks, J. Jr. [Latvia Univ., Riga (Latvia). Dept. of Chemistry; Grishmanov, V.; Tanaka, S.

    1998-03-01

    The radiolysis of Li{sub 2}O ceramics exposed to accelerated electrons (5 MeV) at 380 K was studied in the range of high absorbed doses up to 250 MGy. The formation of radiation defects (RD) and radiolysis products (RP) was demonstrated to occur simultaneously in the regions of (1) the regular crystalline lattice and (2) an enhanced content of the intrinsic defects and impurities. The production of the electronic RD and RP is more efficient in the region of the defected lattice than that at the site of the regular crystalline lattice. However, the stability of RD and RP formed in the region of the intrinsic defects is far less than those produced at the crystalline lattice, since most of the first mentioned RD and RP disappears with irradiation dose due to the radiation stimulated recombination. By this means the enhanced quantity of RD and RP is localized in the Li{sub 2}O ceramics irradiated to absorbed dose of 40-50 MGy, and hence this can influence the tritium release parameters. As soon as the intrinsic defects have been consumed in the production of RD and RP and the recombination of unstable electronic RD and RP takes place (at dose of {approx}100 MGy), the radiolysis of Li{sub 2}O ceramics occurs only at the crystalline lattice. Furthermore, the concentration of RD and RP increases monotonically and tends to the steady-state level. (author)

  17. Water equivalent thickness values of materials used in beams of protons, helium, carbon and iron ions

    OpenAIRE

    Zhang, Rui; Taddei, Phillip J.; Fitzek, Markus M.; Newhauser, Wayne D.

    2010-01-01

    Heavy charged particle beam radiotherapy for cancer is of increasing interest because it delivers a highly conformal radiation dose to the target volume. Accurate knowledge of the range of a heavy charged particle beam after it penetrates a patient’s body or other materials in the beam line is very important and is usually stated in terms of the water equivalent thickness (WET). However, methods of calculating WET for heavy charged particle beams are lacking. Our objective was to test several...

  18. Quantum beam nanolithography

    International Nuclear Information System (INIS)

    Recently, nanotechnology has attracted much attention. Nanotechnology-related research and development have been intensively carried out in the world. Quantum beam nanolithography such as electron beam lithography is expected as a fabrication tool for nanotechnology-related products. For the development of materials capable of fabricating nanostructures, it is important to understand beam-material interaction. We reported radiation-induced reactions in nanolithography materials studied by ISIR subpicosecond pulse radiolysis system. (author)

  19. Evaluation of two water-equivalent phantom materials for output calibration of photon and electron beams

    International Nuclear Information System (INIS)

    Two commercially available water-equivalent solid phantom materials were evaluated for output calibration in both photon (6-15 MV) and electron (6-20 MeV) beams. The solid water 457 and virtual water materials have the same chemical composition but differ in manufacturing process and density. A Farmer-type ionization chamber was used for measuring the output of the photon beams at 5- and 10-cm depth and electron beams at maximum buildup depth in the solid phantoms and in natural water. The water-equivalency correction factor for the solid materials is defined as the ratio of the chamber reading in natural water to that in the solid at the same linear depth. For photon beams, the correction factor was found to be independent of depth and was 0.987 and 0.993 for 6- and 15-MV beams, respectively, for solid water. For virtual water, the corresponding correction factors were 0.993 and 0.998 for 6- and 15-MV beams, respectively. For electron beams, the correction factors ranged from 1.013 to 1.007 for energies of 6 to 20 MeV for both solid materials. This indicated that the water-equivalency of these materials is within ± 1.3%, making them suitable substitutes for natural water in both photon and electron beam output measurements over a wide energy range. These correction factors are slightly larger than the manufacturers' advertised values (± 1.0% for solid water and ± 0.5% for virtual water). We suggest that these corrections are large enough in most cases and should be applied in the calculation of beam outputs

  20. The synthesis and analysis of diuloses and deoxydiuloses with special reference to the radiolysis products of fructose

    International Nuclear Information System (INIS)

    The exposure of fruit to γ-irradiation is a technique that is receiving increasing attention as a practical and economic preservation method. The analysis of irradiated fruit is necessary in order to identify and quantify possible mutagenic and toxic products formed during irradiation. Water and carbohydrates are the main components of fruit, the carbohydrates consisting mainly of mono- and disaccharides. An investigation of the radiolysis products of sugars, with special reference to hexosuloses and hexosdiuloses as possible toxic and/or mutagenic agents, formed the basis of the work described in this thesis. A number of diuloses formally derived from D-fructose was synthesized for mutagenicity tests and as standards for an investigation of the radiolysis products of D-fructose. High pressure liquid chromatography was used as analytical technique. The investigation represents the first application of the technique for the analysis of radiolysis products of sugars. It was succesfully applied to a study of the diuloses formed by the radiolysis of D-fructose in the presence of oxygen. The results obtained confirmed earlier work carried out with GC-MS as analytical technique. In addition, a previously unknown radiolysis product of D-fructose was identified as D-erythrohexos-2,3-diulose

  1. Picosecond pulse radiolysis studies to understand the primary processes in radiolysis

    International Nuclear Information System (INIS)

    The use of pulse radiolysis to learn about processes which occur before the beginning of chemical times is discussed. Two examples, the distance distribution of positive and negative ions in hydrocarbons, and the state of the dry electron are discussed in detail

  2. Radiolysis characterization of chloramphenicol in powder and in eye ointment

    International Nuclear Information System (INIS)

    The effects of γ-radiation sterilization on chloramphenicol, in both pure powder state and petrolatum eye ointment, were investigated with high performance liquid chromatography. The content of chloramphenicol decreases by 1.0% in powder state and by 1.2% in eye ointment at the reference radiation dose of 25 kGy. The profile of chloramphenicol radiolysis products in powder state differs from that in eye ointment. It was found that microenvironment of chloramphenicol molecule is a key factor governing the radiolysis of chloramphenicol in powder state. Solvent residues in chloramphenicol powder could change the radiolysis behavior of chloramphenicol. The solvents, having good solubility for chloramphenicol, promote radiolytic hydrolysis of chloramphenicol, but the converses do not. Inert gas purging or diffusion by exposing in absorbent is efficient method to prevent chloramphenicol powder from radiolysis. The influence of the presence of oxygen was explored. Oxygen plays a role of scavenger and diminishes radiolysis of chloramphenicol. It was found that Nactyl-L-cysteine can protection chloramphenicol in eye ointment from radiolysis. Hydrophobic radiolysis products of chloramphenicol were observed in eye ointment part. Using scavengers and lower irradiation can be strategies to resist radiolysis of chloramphenicol in petrolatum eye ointment. (author)

  3. Gamma radiolysis of aqueous solutions of glycerin α-monochlorohydrin

    International Nuclear Information System (INIS)

    Data on γ-radiolysis of 0.1 mol/l aqueous solutions of glycerin α-monochlorohydrin (GMC) are presented. The radiolysis mechanism is considered. The rate constant of GMC reaction with esub(aq) k=(6.8+-0.8)x108 l/molxs is determined on the basis of experimental data

  4. Study on the gamma radiolysis of poly (vinyl chloride). Application to the study on degradation by irradiation and leaching of industrial PVC

    International Nuclear Information System (INIS)

    The works presented in this memory enter in the context of the management of plastic nuclear waste. This study was carried out on pure PVC and industrial PVC (formulated polymer). The radiolysis at high doses (up to 4 MGy) of pure PVC in anaerobic condition involves the formation of polyenyl radicals, polyenic sequences, hydrogen chloride and reactions of crosslinking. In aerobic condition, the radiolysis at high doses of pure PVC generates the formation of peroxyl radicals, hydrogen chloride, acid water, carboxylic acids, saturated or conjugated ketones and phenomena of scission. The production of HCl generated by irradiation of industrial PVC was carried out up to 40 MGy. The HCl formed by radiolysis is completely trapped by the calcic loads contained in industrial PVC and by the water produced by these reactions of trapping. A qualitative study on the formation of the products of radiolysis highlighted that the mechanisms of radiolysis of industrial PVC are different from those of pure PVC. This difference is due to the presence of additives belonging to the formulation of industrial PVC. The irradiation of plasticizers such as phthalic esters could induce the formation of radicals being able to react, by reaction of grafting, with the macro-radicals of PVC or with the polyenic sequences formed by radiolysis of PVC macromolecules. The results of leaching experiments tend to confirm this type of mechanism. (author)

  5. A bibliographical review on the radiolysis of uranyl nitrate solutions in nitric acid medium

    International Nuclear Information System (INIS)

    A bibliographical study on the effects of ionizing radiation on uranyl nitrate solutions in nitric acid medium was performed, and the state of knowledge on this subject is presented. The main experimental and theoretical results on water, nitric acid and uranium solutions radiolysis are reviewed and critically evaluated. This paper provides a collection of references as an aid to the development of practical applications, and to stimulate new research on fundamental processes in these systems. (author)

  6. On the radiolysis of concentrated alkaline and calcium-nitrate solutions

    International Nuclear Information System (INIS)

    Previous studies have shown that more nitrite is produced than can reasonably be accounted for by an indirect radiolysis mechanism based on the radical products of radiolysed water. Further results on the relative roles of indirect effect and direct effect (a chemical transformation in the solute due to its energy absorption) are presented. Major products are nitrite, peroxide and oxygen and yields can be accounted for using the electron fraction model. (author)

  7. Comparison of Alpha- and Gamma-Ray Radiolysis of Thymine

    International Nuclear Information System (INIS)

    The radiolysis of thymine with polonium-210 alpha particles shows that qualitatively the same products of radiolysis are formed as with X- or gamma rays. In the presence of oxygen thymine hydroperoxide and thymine glycols are the main products of radiolysis with alpha rays. The amount of thymine hydroperoxide is about 30% of all products formed. In the absence of oxygen, thymine glycols, dihydrothymine and its monohydro- xyderivatives and 5-hydroxymethyluracil are formed. These results prove that the OH radical is the main species taking part in the alpha radiolysis of thymine. The presence of dihydrothymine and its derivatives shows the H atom to take part also in the splitting of thymine by alpha particles. Among other products of alpha radiolysis there is a higher percentage of urea and 5-hydroxymethyluracil if compared with gamma rays. (author)

  8. Application of chemsimul for groundwater radiolysis

    DEFF Research Database (Denmark)

    Christensen, Hilbert; Bjergbakke, Erling

    The application of the radiation chemical computer program chemsimul, for the calculation of radiolysis in connection with the storage of high level waste has been studied. Methods have been developed for the diffusion of gases out of the irradiated system, for the continuous addition of Fe2+ to...... and hydrogen was irradiated. In another experiment, the production of Fe(III) and H` by the irradiation of aqueous ferrous sulphate solutions at natural pH values was determined. The agreement between the calculated and experimental results was good in all cases, except for H+ in the last case, where...

  9. Radiolysis of saturated phospholipids. [/sup 60/Co

    Energy Technology Data Exchange (ETDEWEB)

    Handel, A.P.; Nawar, W.W.

    1981-06-01

    Volatile radiolysis products of 1,2-dipalmitoyl-sn-glycerol-3-phosphoethanolamine were recovered by cold-finger distillation and analyzed by gas chromatogrphy and mass spectrometry. They include series of n-alkanes, 1-alkenes, n-alkanals, 2-alkanones, 3-alkanones, 4-alkanones, and methyl and ethyl esters. Quantitative analysis showed that the amounts of products from irradiated 3-sn-phosphatidylethanolamine were strikingly different from those recovered from the acylglycerols. Nonvolatile radiolytic products were separated by thin-layer chromatography. These included palmitic acid, palmitone, lysophosphatidylethanolamine, ethanolamine phosphate, and five unidentified compounds. Possible mechanisms for the formation of these compounds are discussed.

  10. Solubility of oxygen and nitrous oxide in aqueous solutions of NaCl: a pulse radiolysis study

    International Nuclear Information System (INIS)

    The saturation concentrations of O2 and N2O in aqueous solution were measured for different amounts of NaCl by observing the decay of the absorption of hydrated electrons, which were generated during the radiolysis of water. The results are in good agreement with an empirical model based on numerous static measurements of the 'salting-out' effect.

  11. Burnout experiment in subcooled forced-convection boiling of water for beam dumps of a high power neutral beam injector

    International Nuclear Information System (INIS)

    Experimental studies were made on burnout heat flux in highly subcooled forced-convection boiling of water for the design of beam dumps of a high power neutral beam injector for Japan Atomic Energy Research Institute Tokamak-60. These dumps are composed of many circular tubes with two longitudinal fins. The tube was irradiated with nonuniformly distributed hydrogen ion beams of 120 to 200 kW for as long as 10 s. The coolant water was circulated at flow velocities of 3 to 7.5 m/s at exit pressures of 0.4 to 0.9 MPa. The burnout and film-boiling data were obtained at local heat fluxes of 8 to 15 MW/m2. These values were as high as 2.5 times larger than those for the circumferentially uniform heat flux case with the same parameters. These data showed insensitivity to local subcooling as well as to pressure, and simple burnout correlations were derived. From these results, the beam dumps have been designed to receive energetic beam fluxes of as high as 5 MW/m2 with a margin of a factor of 2 for burnout

  12. Nuclear fragmentation of high-energy light-ion beams in water

    International Nuclear Information System (INIS)

    Light-ion beams ranging between carbon and neon with energies of a few hundred MeV/u offer favorable conditions for the treatment of deep-seated tumors. Nuclear fragmentation experiments are presented to study favorable therapy beams simultaneously in thick water target. Comparative measurements with 10B, 12C, 14N, 16O beams are described. (R.P.) 5 refs.; 4 figs

  13. Extension of filament propagation in water with Bessel-Gaussian beams

    OpenAIRE

    KAYA, G.; Kaya, N.; M. Sayrac; Y. Boran; Strohaber, J.; Kolomenskii, A. A.; M. Amani; Schuessler, H. A.

    2016-01-01

    We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size o...

  14. Biradical formation in the radiolysis of cycloalkanes

    International Nuclear Information System (INIS)

    Complete text of publication follows. In the radiolysis and vacuum-ultraviolet photolysis of liquid cycloalkanes structural isomerizations to open-chain olefins, while in the cases of 1,2-, 1,3- and 1,4-dimethylcycloalkanes also geometrical (cis↔trans) isomerizations were observed. Biradicals are suggested as intermediates of these isomerizations. Iodine scavenging studies, similar to that previously performed for n-alkanes and isoalkanes, were made in the γ radiolysis of cyclopentane, cyclohexane, cycloheptane, cyclooctane and cyclodecane. Using gel permeation chromatography (GPC) for the separation of iodide scavenging products αω-diiodo alkanes were also found to form in addition to the usual scavenging products, cycloalkyl iodides and fragment iodoalkanes. The production of αω- diiodo alkanes was attributed to biradical scavenging. The diiodo alkane yields showed a strong dependence on iodine concentration revealing a Stern-Volmer type competition between unimolecular stabilization of the biradicals forming hydrocarbon products and the radical scavenging reaction. This competition allowed to estimate the biradical lifetimes, 100-600 ns, and the biradical yields, G = 0.06 - 0.25 biradical/100 eV.

  15. Radiolysis of cyanocobalamin (vitamin B12)

    International Nuclear Information System (INIS)

    Research on the radiolysis of vitamins is of considerable interest since these compounds are important nutritional constituents in foods and in dietetic supplements. In spite of these considerations there are few data and very often difficult to compare for the radiolytic behavior of vitamins. In this work we focused our attention on to the study of the radiolysis of cyanocobalamin (vitamin B12) in solid state and in aqueous solutions. The procedure was followed by HPLC and UV-spectroscopy. The results obtained in aqueous solutions showed a dependence of the decomposition as a linear function of the dose. The G of decomposition for a 1x10-5 M solution was 3.3. In the solid state the vitamin was very stable towards the irradiation in the conditions used in this study with a G=2.1x10-3. A study made with Serratia marcescens as a microbiological contaminant showed that at the sterilization dose there is a destruction of the vitamin in aqueous solution. In the solid state the degree of decomposition was 7%. (author)

  16. Radiolysis in cement-based materials ; application to radioactive waste-forms

    International Nuclear Information System (INIS)

    Cement-based materials appear to be an original environment with respect to radiolysis, due to their intrinsic complexity (porous, multiphasic and evolutional medium) or their very specific physico-chemical conditions (hyper-alkaline medium with pH ≥ 13, high content in calcium) or by the fact of numerous couplings existing between different phenomenologies. At the level of a radioactive cemented wasteform, a high degree of complexity is reached, in particular if the system communicates with the atmosphere (open system allowing regulation of the pressures but also the admission of O2, strong reactive with regards to radiolysis). Then, the radiolysis description exceeds widely the only one aspect of the decomposition of alkaline water under irradiation and makes necessary a global phenomenological approach. In this context, some 'outlying' phenomena, highly coupled with radiation chemistry, have to be taken into account because they contribute to deeply modify the net result of the radiolysis: radioactive decay of multiple αβγ emitters with filiation, phase changes (for example H2 aq → H2 gas) within the pores, gas transport by convection (Darcy law) and by diffusion (Fick law), precipitation/dissolution of solid phases, effect of the ionic strength and the temperature, disturbances connected to the presence of some solutes with redox potentialities (iron, sulphur). The integration work carried out on the previous points leads to an operational model (DOREMI) allowing the estimate of H2 amounts produced by radiolysis in different cemented radioactive waste-forms. As the final expression of the model, numerical simulations constitute a relevant tool of expertise and prospecting, contributing to accompany the thought on radiolysis in cement matrices in general and in cemented waste-forms in particular. Starting from different examples, simulations can be so used in order to test some hypotheses or illustrate the greatest influence of gas transport, dose rate

  17. Lead Pipe Scale Analysis Using Broad-Beam Argon Ion Milling to Elucidate Drinking Water Corrosion

    Science.gov (United States)

    Herein, we compared the characterization of lead pipe scale removed from a drinking water distribution system using two different cross section methods (conventional polishing and argon ion beam etching). The pipe scale solids were analyzed using scanning electron microscopy (SEM...

  18. Extension of filament propagation in water with Bessel-Gaussian beams

    Science.gov (United States)

    Kaya, G.; Kaya, N.; Sayrac, M.; Boran, Y.; Strohaber, J.; Kolomenskii, A. A.; Amani, M.; Schuessler, H. A.

    2016-03-01

    We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size of the central peak of the incident beam, suggesting that the radial modal lobes may serve as an energy reservoir for the filaments formed by the central intensity peak.

  19. Extension of filament propagation in water with Bessel-Gaussian beams

    Directory of Open Access Journals (Sweden)

    G. Kaya

    2016-03-01

    Full Text Available We experimentally studied intense femtosecond pulse filamentation and propagation in water for Bessel-Gaussian beams with different numbers of radial modal lobes. The transverse modes of the incident Bessel-Gaussian beam were created from a Gaussian beam of a Ti:sapphire laser system by using computer generated hologram techniques. We found that filament propagation length increased with increasing number of lobes under the conditions of the same peak intensity, pulse duration, and the size of the central peak of the incident beam, suggesting that the radial modal lobes may serve as an energy reservoir for the filaments formed by the central intensity peak.

  20. Improvements in detection system for pulse radiolysis facility

    International Nuclear Information System (INIS)

    This report describes the improvements made in the detection system of the pulse radiolysis facility based on a 7 MeV Linear Electron Accelerator (LINAC) located in the Radiation Chemistry and Chemical Dynamics Division of Bhabha Atomic Research Centre. The facility was created in 1986 for kinetic studies of transient species whose absorption lies between 200 and 700 nm. The newly developed detection circuits consist of a silicon (Si) photodiode (PD) detector for the wavelength range 450-1100 nm and a germanium (Ge) photodiode detector for the wavelength range 900-1600 nm. With these photodiode-based detection set-up, kinetic experiments are now routinely carried out in the wavelength range 450-1600 nm. The performance of these circuits has been tested using standard chemical systems. The rise time has been found to be 150 ns. The photo-multiplier tube (PMT) bleeder circuit has been modified. A new DC back-off circuit has been built and installed in order to avoid droop at longer time scales. A steady baseline upto 10 s with PMT and upto 100 s with PD is available without any droop. The RF interference generated during the delivery of the electron beam pulse by the LINAC normally limits the measurements below 20 mV signal. The introduction of a fibre optic cable between the LINAC cave and the data acquisition laboratory has enabled us to analyse even weak signals of the order of 5 mV. (author)

  1. Ground-water activation from the upcoming operation of MI40 beam absorber

    International Nuclear Information System (INIS)

    During the course of normal operation, a particle accelerator can produce radionuclides in the adjacent soil and in the beam line elements through the interactions of accelerated particles and/or secondary particles produced in the beam absorbers, targets, and sometimes elsewhere through routine beam losses. The production and concentration of these radionuclides depends on the beam parameters such as energy, intensity, particle type, and target configuration. The radionuclides produced in the soil can potentially migrate to the ground water. Soil activation and migration to the ground water depends on the details of the local hydrogeology. Generally, very few places such as the beam stops, target stations, injection and extraction sectors can have high enough radiation fields to produce radionuclides in the soil outside the enclosures. During the design, construction, or an upgrade in the intensity of existing beams, measures are taken to minimize the production of activated soil. The only leachable radionuclides known to be produced in the Fermilab soil are 3H, 7Be , 22Na, 45Ca and 54Mn and it has been determined that only 3H, and 22Na, because of their longer half lives and greater leachabilities, may significantly impact ground water resources.In the past, Fermilab has developed and used the Single Resident Well Model (SRWM) to estimate the ground water activation. Recently, the Concentration Model (CM), a more realistic method which depends on the site hydrogeology has been developed to decide the shielding requirements of the high radiation sites, and to calculate the ground water activation and its subsequent migration to the aquifer. In this report, the concentration of radionuclide released to the surface waters and the aquifer around the MI40 beam absorber are calculated. Subsequently, the ultimate limit on the primary proton beam intensity to be aborted on the Main Injector beam absorber is determined

  2. Double beam near-infrared spectrometer for compensation of background water absorption and instrumental drift in intensity

    Institute of Scientific and Technical Information of China (English)

    CHANG Min; PENG Dan; XU Ke-xin

    2007-01-01

    A double beam near-infrared spectrometer is developed to compensate the water absorption and instrumental drift in intensity. The spectrometer maybe used for both single and double beam measurements, and the two operation modes are compared. The results show that the double beam technique eliminates instrumental drift in the single beam measurement and therefore the stability of the system increases by more than 20%. The compensation of the double beam system on water absorption is verified by the measurement of fat content in milk. The results show that the spectrum data based on double beam mode get better calibration model and lower prediction error than traditional single beam mode.

  3. Organic compounds destruction by a relativistic electron beam in waste-waters

    International Nuclear Information System (INIS)

    The electron beam influence on the decomposition of organic compounds in effluents has been investigated. In the tests, waste-water has been processed with a relativistic electron beam f the energy 3...4 MeV, formed with a linear resonance accelerator. The model samples of the following solutions have been put on trial: nitrite-, nitrate-, ammonium- and phosphate ions, glucose and purified kerosene. The results of the investigations have indicated that the application of relativistic electron beams is prospective for the water purification from these organic compounds

  4. Gamma-radiolysis of dimethyl sulfoxide. II. Radiolysis yields and possible mechanisms

    International Nuclear Information System (INIS)

    As result of quantitative studies on gamma-radiolysis of DMSO at a dose range of 90-850 Mrads, constant G values have been obtained for the following radiolysis compounds: G(-DMSO) - 6.7 ±0.2; G(dimethyl sulphide) - 3.4 ±0.3; G(methane) - 0,75 ± 0.04; G(dimethyl disulphide) -0.33 ±0,03; G(tri methylsulphonium methanesulphonate) - 0.26 ± 0,01; G(methyl methanethiosulphonate) - 0,25 ±0.02; G(dimethyl sulphona)-0.21±0.02; G(H2)-0.18±0.02; and G(propane)--0.0092±0.0007. Initial G values have been obtained for other identified compounds: Gi(ethane)-0,46; Gi(CO)-0.052; and Gi(CO2)-0.030. Possible mechanisms on the radiolysis process are proposed. (Author) 17 refs

  5. Calculated LET Spectrum from Antiproton Beams Stopping in Water

    DEFF Research Database (Denmark)

    Bassler, Niels; Holzscheiter, Michael

    2009-01-01

    Antiprotons have been proposed as a potential modality for radiotherapy because the annihilation at the end of range leads to roughly a doubling of physical dose in the Bragg peak region. So far it has been anticipated that the radiobiology of antiproton beams is similar to that of protons in the...

  6. Pulse Radiolysis of Aqueous Thiocyanate Solution

    International Nuclear Information System (INIS)

    The pulse radiolysis of N2O saturated aqueous solutions of KSCN was studied under neutral pH conditions. The observed optical absorption spectrum of the SCN#lgbullet# radical in solution is more complex than previously reported, but it is in good agreement with that measured in the gas phase. Kinetic traces at 330 nm and 472 nm corresponding to SCN#lgbullet# and (SCN)2#lgbullet#-, respectively, were fit using a Monte Carlo simulation kinetic model. The rate coefficient for the oxidation of SCN- ions by OH radicals, an important reaction used in competition kinetics measurements, was found to be 1.4 ± 0.1 x 1010 M-1 s-1, about 30% higher than the normally accepted value. A detailed discussion of the reaction mechanism is presented

  7. Radiolysis of Ca14CO3

    International Nuclear Information System (INIS)

    The partition-ion exclusion chromatography is evaluated to analyse non-ionic organic compounds obtained from radiolysis of high specific activity Ca14CO3. The Ca14CO3 was irradiated by β- decay of carbon-14 or by γ rays from a cobalt-60 source. The crystals were dissolved for qualitative and quantitative analysis of the radiolytic products. Formic and oxalic acids were produced in high yields. Glyoxylic, acetic and glycolic acids, formaldehyde and methanol were produced in low yields. Quantitative determination was carried out by liquid scintillation spectroscopy and the chemical yields (G-values) were calculated for the products. Mechanisms of product formation are proposed based on thermal annealing experiments. (Author)

  8. Nanometer and ultrafine aerosols from radon radiolysis

    International Nuclear Information System (INIS)

    The ability of ionizing radiation to produce condensation nuclei aerosols in filtered air is well known. Recent studies have indicated that radiolysis results initially in the production of highly diffusive, nanometer-sized (5 nm) can then evolve by coagulation and growth processes. The nanometer nuclei are, however, poorly detected by condensation nuclei counters (CNCs) since CNC efficiencies drop sharply for particle sizesx molecular cluster aerosols from the decay of radon, and sulfuric acid nanometer nuclei and ultrafine aerosols from the radiolytic oxidation of SO2 in radon-air mixtures, were studied through wire screen-based size distribution measurements of the 218Po radioactivity associated with the aerosols. Comparisons with conventional diffusion battery-CNC derived number size distributions are also presented. (author)

  9. Radiolysis of ethylenpropylic/divinylbenzene elastomer systems

    International Nuclear Information System (INIS)

    In this paper the γ-radiolysis of blends consisting of ethylene-propylene terpolymer (EPDM) and divinylbenzene (DVB) exposed to 137Cs source is presented. Radiation processing at various doses up to about 100 kGy was accomplished. In order to establish the influence of vinyl compound concentration, several specimens containing DVB were radiochemically modified. The highest percentage of the DVB component in the studied mixtures was 30 %. For the evaluation of thermal stability of radiolysed samples, the oxygen uptake method was applied. It was proved that the increase in DVB concentration brought about the improvement of the thermal strength of radiation modified blends. Over the low dose range, the oxidation rate of mixtures consisting of EPDM and low concentration of DVB exceeded the thermal degradation of unmixed elastomer. (author)

  10. Utilization of high energy electron beam in the treatment of drinking and waste water

    International Nuclear Information System (INIS)

    Samples of drinking water and waste water were irradiated using high energy electron beam with doses from 0.37kGy to 100kGy. Preliminary data show the removal of about 100% tri halomethanes (THM) in drinking water (concentration from 2.7 μg/1 to 45μg/1, 90% of the color of the Public Owned Wastewater Treatment Plant effluent and 87% of oil and grease of the cutting fluid waste water. (author)

  11. The radiation chemistry of CMPO: Part 2. Alpha radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Bruce J. Mincher; Stephen P. Mezyk; Gary S. Groenewold; Christian Ekberg; Gunnar Skarnemark; Jay A. LaVerne; Mikael Nilsson; Jeremy Pearson; Nicholas C. Schmitt; Richard D. Tillotson; Lonnie G. Olson; Gracy Elias

    2014-01-01

    Octylphenyl-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in dodecane was subjected to a-irradiation using a He-ion beam, 244 Cm isotopic a-rays, and He and Li ions created by the n,a reaction of 10B in a nuclear reactor. Post-irradiation samples were analyzed for the radiolytically-induced decrease in CMPO concentration, the appearance of degradation products, and their Am solvent extraction distribution ratios. The –G CMPO-value for the radiolytic degradation of CMPO was found to be very low compared to values previously reported for ?-irradiation. Additionally, isotopic irradiation to absorbed a-doses as high as 600 kGy in aerated solution had no effect on Am solvent extraction or stripping. The main CMPO radiolysis products identified in He-ion beam irradiated samples by ESI-MS include amides, an acidic amide, and amines produced by bond rupture on either side of the CMPO carbonyl group. Deaerated samples irradiated using the reactor in the absence of an aqueous phase, or with a dilute nitric acid aqueous phase showed small but measurable decreases in CMPO concentration with increasing absorbed doses. Higher concentrations of nitric acid resulted in lower decomposition rates for the CMPO. The radio-protection by dissolved oxygen and nitric acid previously found for ?-irradiated CMPO also occurs for a-irradiation. This suggests that similar free-radical mechanisms operate in the high-LET system, but with lower degradation yields due to the lower overall radical concentrations produced.

  12. Verification of computer code for calculation of coolant radiolysis in the VVER reactor core with regard for boiling in its upper part

    International Nuclear Information System (INIS)

    Code Bora for WWER coolant radiolysis calculation considering single jets boiling in the reactor core top part is developed on the basis of computer codes MOPABA-H2 (radiolysis of aqueous solutions) and SteamRad (radiolysis of vapor). Physico-chemical processes taking place in boiling core coolant are complex and diversified. Still, for the solution of certain problems their simulation can be simplified. The approach of reasonable simplification was used for development of code Bora: mathematical model assumed is purposed for simulation of phenomena only in the area of interest; the number of simulated chemical reactions and particles shall be reasonably minimum; complexity of interphase mass transfer calculation procedure shall be adequate to actually available accuracy of modeling. The analysis of new experimental initial yields of water radiolysis products data and kinetic parameters of elementary chemical reactions with their participation has been carried out. Some changes have been introduced in the mechanism of liquid water and aqueous solutions of ammonia radiolysis have been significantly revised on the basis of this analysis. Examples of the calculations provided for code Bora verification are presented. Despite of very simple simulation of interphase mass transfer, Bora allows to obtain average chemical composition of two-phase coolant at BWR core outlet with the accuracy sufficient for engineering calculations. The report also presents the results of two-phase coolant chemical composition test calculation for reactor core top part coolant boiling in pressurized water reactor. (author)

  13. Radiolysis of aqueous solutions of sodium sulfides. Chapter 8

    International Nuclear Information System (INIS)

    To study the radiolysis of the aqueous solutions of sodium sulphide, use was made of infrared spectroscopy, mass-spectrometry and iodometric titration. During the γ-irradiation of the aqueous solutions of sodium sulphide one can observe the appearance of various stable sulphur-containing products. Data are discussed on the radiolysis in a nitrous environment, on oxygen bubbling, at varying radiation doses, pH and temperature values. Consideration is also given to the low-temperature radiolysis of the aqueous solutions of sodium sulphide by the EPR method. In the radiolysis of both crystalline and glassy solutions of Na2S there appear an ion-radical S- and a radical SO2-

  14. Subpicosecond pulse radiolysis studies on spur reactions and nanotechnology

    International Nuclear Information System (INIS)

    Recently we developed a subpicosecond pulse radiolysis system, although the time resolution of pulse radiolysis had remained about 30 ps for these 30 years. Time resolution and S/N ratio have been improved dramatically. The subpicosecond pulse radiolysis is a very powerful method to detect and observe transient phenomena in radiation chemistry and physics within 30 ps. By using the subpicosecond pulse radiolysis, many researches have been carried out on ultrafast phenomena in radiation chemistry, physics, biology and applied fields such as material science.Especially the spur reaction, which is one of the most important reactions in radiation chemistry, physics and biology, has been studied in the very wide time range from subpicosecond to several hundred nanoseconds by very high S/N ratio. These experimental results were analyzed theoretically and applied to the basic data for nanofabrication, which are very important in both next generation lithography and nanotechnology

  15. Enhanced solar water splitting of electron beam irradiated titania photoanode by electrostatic spray deposition

    International Nuclear Information System (INIS)

    Highlights: • TiO2 thin-film photoelectrodes were prepared by electrostatic spray deposition (ESD). • Photoactivity of an electrosprayed titania film could be greatly enhanced by the use of electron beam irradiation. • The application of the electron beam was found to increase the photocurrent density threefold over a non-electron beam-treated film. - Abstract: Surface modifications are often made to titania films to improve its photocatalytic performance in water splitting. We herein introduced electron beam irradiation to enhance the photocatalytic activities of an electro-sprayed titania film for solar water splitting application. The film was fabricated by a facile and scalable electrostatic spraying deposition. According to SEM, X-ray diffraction, and Raman data, electron beam densified the film and improved its crystallinity. Absorbance data indicated that the band gap of the E-beam film reduced, which in turn covered the wider range of absorbed light. These modifications increased oxygen vacancies or defects, which enhanced mobility and separation of electrons and holes. As a result, the E-beam film exhibited a threefold increase in the photocurrent density, compared to that of the non-E-beam film. This electrosprayed titania film was used as a photoanode while the reference and counter electrodes involved in the generation of hydrogen were made of Ag/AgCl and platinum, respectively. The intensity of the UV light illumination used was 1 mW/cm2

  16. Protection in radiolysis of n-hexadecane. Pt. 1

    International Nuclear Information System (INIS)

    Radiolysis of pure liquid n-hexadecane under vacuum has been studied to obtain greater understanding about the effect of radiation on open chain polymers such as polyethylene. Gas chromatography, gel permeation chromatography and mass spectrometry have been used to analyze the radiolysis products and their yields have been determined. The gas products mainly contain H2, the condensed products contain saturated and unsaturated scission products, hexadecene and crosslink products. Mass analysis of the condensed products shows unsaturations in the crosslink products. (author)

  17. Radiolysis studies of uranyl nitrate solution in nitric acid medium

    International Nuclear Information System (INIS)

    The radiolysis of acidic uranyl nitrate solutions was investigated using Co-60 gamma radiation. Hydrogen peroxide was determined as a function of increasing dose. The UV-vis absorption spectra of the irradiated solutions were measured and the spectral changes were analyzed. The increasing dose increases the absorbance intensities, possibly by an increment in nitrate concentration produced by radiolysis, which can originate the formation of different uranyl complexes in solution. (author)

  18. Water equivalent thickness values of materials used in beams of protons, helium, carbon and iron ions.

    Science.gov (United States)

    Zhang, Rui; Taddei, Phillip J; Fitzek, Markus M; Newhauser, Wayne D

    2010-05-01

    Heavy charged particle beam radiotherapy for cancer is of increasing interest because it delivers a highly conformal radiation dose to the target volume. Accurate knowledge of the range of a heavy charged particle beam after it penetrates a patient's body or other materials in the beam line is very important and is usually stated in terms of the water equivalent thickness (WET). However, methods of calculating WET for heavy charged particle beams are lacking. Our objective was to test several simple analytical formulas previously developed for proton beams for their ability to calculate WET values for materials exposed to beams of protons, helium, carbon and iron ions. Experimentally measured heavy charged particle beam ranges and WET values from an iterative numerical method were compared with the WET values calculated by the analytical formulas. In most cases, the deviations were within 1 mm. We conclude that the analytical formulas originally developed for proton beams can also be used to calculate WET values for helium, carbon and iron ion beams with good accuracy. PMID:20371908

  19. Direct measurement of electron beam quality conversion factors using water calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Renaud, James, E-mail: james.renaud@mail.mcgill.ca; Seuntjens, Jan [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4 (Canada); Sarfehnia, Arman [Medical Physics Unit, McGill University, Montréal, Québec H3G 1A4, Canada and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 3E2 (Canada); Marchant, Kristin [Allan Blair Cancer Centre, Saskatchewan Cancer Agency, Regina, Saskatchewan S4T 7T1, Canada and Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5A1 (Canada); McEwen, Malcolm; Ross, Carl [Ionizing Radiation Standards, National Research Council of Canada, Ottawa, Ontario K1A 0R6 (Canada)

    2015-11-15

    Purpose: In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. Methods: A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. Results: The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9–20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%–0.40%) and its influence on the perturbation correction (Type B, 0.10%–0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, k{sub ecal}, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM’s TG-51 protocol

  20. Direct measurement of electron beam quality conversion factors using water calorimetry

    International Nuclear Information System (INIS)

    Purpose: In this work, the authors describe an electron sealed water calorimeter (ESWcal) designed to directly measure absorbed dose to water in clinical electron beams and its use to derive electron beam quality conversion factors for two ionization chamber types. Methods: A functioning calorimeter prototype was constructed in-house and used to obtain reproducible measurements in clinical accelerator-based 6, 9, 12, 16, and 20 MeV electron beams. Corrections for the radiation field perturbation due to the presence of the glass calorimeter vessel were calculated using Monte Carlo (MC) simulations. The conductive heat transfer due to dose gradients and nonwater materials was also accounted for using a commercial finite element method software package. Results: The relative combined standard uncertainty on the ESWcal dose was estimated to be 0.50% for the 9–20 MeV beams and 1.00% for the 6 MeV beam, demonstrating that the development of a water calorimeter-based standard for electron beams over such a wide range of clinically relevant energies is feasible. The largest contributor to the uncertainty was the positioning (Type A, 0.10%–0.40%) and its influence on the perturbation correction (Type B, 0.10%–0.60%). As a preliminary validation, measurements performed with the ESWcal in a 6 MV photon beam were directly compared to results derived from the National Research Council of Canada (NRC) photon beam standard water calorimeter. These two independent devices were shown to agree well within the 0.43% combined relative uncertainty of the ESWcal for this beam type and quality. Absorbed dose electron beam quality conversion factors were measured using the ESWcal for the Exradin A12 and PTW Roos ionization chambers. The photon-electron conversion factor, kecal, for the A12 was also experimentally determined. Nonstatistically significant differences of up to 0.7% were found when compared to the calculation-based factors listed in the AAPM’s TG-51 protocol. General

  1. Gamma and Neutron Radiolysis in the 21-PWR Waste Package

    International Nuclear Information System (INIS)

    The objective of this calculation is to compute gamma and neutron dose rates in order to determine the maximum radiolytic production of nitric acid and other chemical species inside the 21-PWR (pressurized-water reactor) waste package (WP). The scope of this calculation is limited to the time period between 5,000 and 100,000 years after emplacement. The information provided by the sketches attached to this calculation is that of the potential design for the type of WP considered in this calculation. The results of this calculation will be used to evaluate nitric acid corrosion of fuel cladding from radiolysis in the 21-PWR WP. This calculation was performed in accordance with the Technical Work Plan for: Waste Package Design Description for LA (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000a). AP-3.124, Calculations, is used to perform the calculation and develop the document. This calculation is associated with the total system performance assessment (TSPA) of which the spent fuel cladding integrity is to be evaluated

  2. The radiolysis in the nuclear-chemical extraction systems

    International Nuclear Information System (INIS)

    In the first part, the progress of research works including spent fuel reprocessing of nuclear power reactor, process chemistry of uranium, plutonium, actinides, lanthanoids and fission products and radiation chemistry including photochemistry is reviewed. in the second part, works of the author in radiation processes and photochemical processes in extraction systems used in spent fuel reprocessing of nuclear power reactor, (namely) in tri-n-butylphosphate, di-n-butylphosphate, tritolylphosphate, di-n-butyl-butylphosphonate bis(2-ethylhexyl)phosphoric acid, cobalt(III) dicarbollide, nitrobenzene, carbon tetrachloride, chlorobenzene and its one-phase and liquid-liquid two-phase systems with water or nitric acid solutions, and crown-ethers (12-crown-4, 15-crown-5, dicyclohexano-24-crown-8 and their analogues tetrahydrofuran and 1,4-dioxane) which were studied with GC-MS, GC-FTIR, HPLC, capillary isotachophoresis, UV-VIS and EPR spectroscopy, preparative or laser flash photolysis, steady state and pulse radiolysis and other methods are reviewed.(author) The 24 papers is presented in the appendix. 469 refs., 17 tabs. 2 figs

  3. An Advantage of the Equivalent Velocity Spectroscopy for Femtsecond Pulse Radiolysis

    CERN Document Server

    Kondoh, Takafumi; Tagawa, Seiichi; Tomosada, Hiroshi; Yang Jin Feng; Yoshida, Yoichi

    2005-01-01

    For studies of electron beam induced ultra-fast reaction process, femtosecond(fs) pulse radiolysis is under construction. To realize fs time resolution, fs electron and analyzing light pulses and their jitter compensation system are needed. About a 100fs electron pulse was generated by a photocathode RF gun linac and a magnetic pulse compressor. Synchronized Ti: Sapphire laser have a puleswidth about 160fs. And, it is significant to avoid degradation of time resolution caused by velocity difference between electron and analyzing light in a sample. In the 'Equivalent velocity spectroscopy' method, incident analyzing light is slant toward electron beam with an angle associated with refractive index of sample. Then, to overlap light wave front and electron pulse shape, electron pulse shape is slanted toward the direction of travel. As a result of the equivalent velocity spectroscopy for hydrated electrons, using slanted electron pulse shape, optical absorption rise time was about 1.4ps faster than normal electro...

  4. Pulse radiolysis study on several fluoroquinolones

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Peng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Science, Beijing 100049 (China); Yao Side [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Li Haixia; Song Xiyu; Liu Yancheng [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate University of Chinese Academy of Science, Beijing 100049 (China); Wang Wenfeng, E-mail: wangwenfeng@sinap.ac.c [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

    2011-04-15

    Reactions of several fluoroquinolones (FQs), including enoxacin, norfloxacin, and ciprofloxacin, with various reactive species such as e{sub aq}{sup -}, N{sup {center_dot}}{sub 3}, and {sup {center_dot}O}H are investigated by pulse radiolysis techniques. The FQ radical anions formed in the reactions of FQs with e{sub aq}{sup -} could either be protonated or deprotonated, and the absorption of FQ radical anions was located around 370 nm. The absorption of the neutral radicals produced in the protonation, and the radical dianions produced in the deprotonation of FQ radical anions were located in the 500-750 nm region. The FQ radical cations formed in the reactions of FQs with N{sub 3}{sup {center_dot}} showed an absorption band around 360 nm. Due to the strong bleaching below 350 nm, the absorption maxima ({lambda}{sub max}) of FQ radical anions, and the {lambda}{sub max} of FQ radical cations were not confirmed. The absorption of the FQ radical anions and cations was clearly pH dependent. Under neutral conditions, the reaction rate constants of FQs with e{sub aq}{sup -} and {sup {center_dot}O}H, which are diffusion controlled, were determined.

  5. Evaluation of thermoluminescent dosimeters using water equivalent phantoms for application in clinical electrons beams dosimetry

    International Nuclear Information System (INIS)

    The dosimetry in Radiotherapy provides the calibration of the radiation beam as well as the quality control of the dose in the clinical routine. Its main objective is to determine with greater accuracy the dose absorbed by the tumor. This study aimed to evaluate the behavior of three thermoluminescent dosimeters for the clinical electron beam dosimetry. The performance of the calcium sulfate detector doped with dysprosium (CaSO4: Dy) produced by IPEN was compared with two dosimeters commercially available by Harshaw. Both are named TLD-100, however they differ in their dimensions. The dosimeters were evaluated using water, solid water (RMI-457) and PMMA phantoms in different exposure fields for 4, 6, 9, 12 and 16 MeV electron beam energies. It was also performed measurements in photon beams of 6 and 15 MV (2 and 5 MeV) only for comparison. The dose-response curves were obtained for the 60Co gamma radiation in air and under conditions of electronic equilibrium, both for clinical beam of photons and electrons in maximum dose depths. The sensitivity, reproducibility, intrinsic efficiency and energy dependence response of dosimeters were studied. The CaSO4: Dy showed the same behavior of TLD-100, demonstrating only an advantage in the sensitivity to the beams and radiation doses studied. Thus, the dosimeter produced by IPEN can be considered a new alternative for dosimetry in Radiotherapy departments. (author)

  6. Measurements of absorbed energy distributions in water from pulsed electron beams

    International Nuclear Information System (INIS)

    An evaluation of the use of a holographic interferometer to measure the energy deposition as a function of depth in water from pulsed electron beams, together with a brief description of the interferometer and the technique of generating a hologram are presented. The holographic interferometer is used to measure the energy deposition as a function of depth in water from various pulsed beams of monoenergetic electrons in the energy range from 1.0 to 2.5 MeV. These results are compared to those computed by using a Monte Carlo radiation transport code, ETRAN-15, for the same electron energies. After the discrepancies between the measured and computed results are evaluated, reasonable agreement is found between the measured and computed absorbed energy distributions as a function of depth in water. An evalutation of the response of the interferometer as a function of electron intensities is performed. A comparison among four energy deposition curves that result from the irradiation of water with pulsed electron beams from a Febetron accelerator, model 705, is presented. These pulsed beams were produced by the same vacuum diode with the same charging voltage. The results indicate that the energy distribution of the electrons in the pulsed beam is not always constant. A comparison of the energy deposition curves that result from the irradiation of water with electron pulses from different vacuum diodes but the same charging voltage is presented. These results indicate again that the energy distribution of the electrons in the pulsed beam may vary between vacuum diodes. These differences would not be realized by using a totally absorbing metal calorimeter and Faraday Cup

  7. On the problem of change of higher structure of albumin during radiolysis

    International Nuclear Information System (INIS)

    By the polarographic method in aqueous solutions the γ-radiation denaturation of molecules of human serum albumin (HSA) at lower absorbed doses (2-2x103 Gy for protein and 0.15-1.65 Gy for serum) is studied. It is shown that the presence of three maxima on dependence curves of cobalt ion reduction current, bound with protein on irradiation dose, testify to step-like character of protein radiation denaturation. Three types of bonds different in accessibility for the attack by water radiolysis products, stabilizing higher structure of albumin, are revealed

  8. Temperature Measurement and Water Flow Calorimetry for the Neutral Beam Test Stand Operation at KAERI

    International Nuclear Information System (INIS)

    Temperature measurements during the beam line operation of the neutral beam test stand(NB-TS) is very important for the estimation of the absorbed energy by the beam line components such calorimeter and also for the temperature monitoring of the various components, and have been accomplished by the utilization of many of the thermocouples(TCs) installed onto the NB-TS and the data acquisition system(DAQ) based on the National Instruments' (NI) SCXI system. Preliminary estimations of the absorbed energy by the calorimeter during the beam extraction have been made. Greater efforts for the noise reduction in the TC signal acquisition has been made with partial success. We present the status of the temperature measurement and water flow calorimetry(WFC) related to the NB-TS operations

  9. Direct measurement of a proton beam passing through a water target by the induced change in the water conductivity

    International Nuclear Information System (INIS)

    A water target for use in a neutrino experiment at the Los Alamos Meson Physics Facility was constructed with monitors to measure the transient change in water conductivity induced by the passage of the proton beam. This novel monitoring technique permitted a direct measure of the 800-MeV incident proton beam inside the target and gave a measure of the beam alignment. The conductivity persisted over many milliseconds and exhibited an exponential time decay after the beam pulse ended with a characteristic time constant consistent with the production and recombination of OH- and H3O+ ions in the water. Though the concentration of these ions was observed to increase linearly with the incident proton current, when compared to the formation of ion-pairs by direct energy loss of the incident protons, the process producing the more stable conduction ions observed in this experiment was found to be many orders of magnitude less efficient. The cause of this inefficiency is not understood, but suggests one or more intermediate processes are involved in their production

  10. Geant4 Simulation Study of Dose Distribution and Energy Straggling for Proton and Carbon Ion Beams in Water

    OpenAIRE

    Zhao Qiang; Zhang Zheng; Li Yang

    2016-01-01

    Dose distribution and energy straggling for proton and carbon ion beams in water are investigated by using a hadrontherapy model based on the Geant4 toolkit. By gridding water phantom in N×N×N voxels along X, Y and Z axes, irradiation dose distribution in all the voxels is calculated. Results indicate that carbon ion beams have more advantages than proton beams. Proton beams have bigger width of the Bragg peak and broader lateral dose distribution than carbon ion beams for the same position o...

  11. Pink-Beam, Highly-Accurate Compact Water Cooled Slits

    International Nuclear Information System (INIS)

    Advanced Design Consulting, Inc. (ADC) has designed accurate compact slits for applications where high precision is required. The system consists of vertical and horizontal slit mechanisms, a vacuum vessel which houses them, water cooling lines with vacuum guards connected to the individual blades, stepper motors with linear encoders, limit (home position) switches and electrical connections including internal wiring for a drain current measurement system. The total slit size is adjustable from 0 to 15 mm both vertically and horizontally. Each of the four blades are individually controlled and motorized. In this paper, a summary of the design and Finite Element Analysis of the system are presented

  12. Luminescence imaging of water during proton-beam irradiation for range estimation

    International Nuclear Information System (INIS)

    Purpose: Proton therapy has the ability to selectively deliver a dose to the target tumor, so the dose distribution should be accurately measured by a precise and efficient method. The authors found that luminescence was emitted from water during proton irradiation and conjectured that this phenomenon could be used for estimating the dose distribution. Methods: To achieve more accurate dose distribution, the authors set water phantoms on a table with a spot scanning proton therapy system and measured the luminescence images of these phantoms with a high-sensitivity, cooled charge coupled device camera during proton-beam irradiation. The authors imaged the phantoms of pure water, fluorescein solution, and an acrylic block. Results: The luminescence images of water phantoms taken during proton-beam irradiation showed clear Bragg peaks, and the measured proton ranges from the images were almost the same as those obtained with an ionization chamber. Furthermore, the image of the pure-water phantom showed almost the same distribution as the tap-water phantom, indicating that the luminescence image was not related to impurities in the water. The luminescence image of the fluorescein solution had ∼3 times higher intensity than water, with the same proton range as that of water. The luminescence image of the acrylic phantom had a 14.5% shorter proton range than that of water; the proton range in the acrylic phantom generally matched the calculated value. The luminescence images of the tap-water phantom during proton irradiation could be obtained in less than 2 s. Conclusions: Luminescence imaging during proton-beam irradiation is promising as an effective method for range estimation in proton therapy

  13. Luminescence imaging of water during proton-beam irradiation for range estimation

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Okumura, Satoshi; Komori, Masataka [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Nagoya 461-8673 (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Nagoya 462-8508 (Japan)

    2015-11-15

    Purpose: Proton therapy has the ability to selectively deliver a dose to the target tumor, so the dose distribution should be accurately measured by a precise and efficient method. The authors found that luminescence was emitted from water during proton irradiation and conjectured that this phenomenon could be used for estimating the dose distribution. Methods: To achieve more accurate dose distribution, the authors set water phantoms on a table with a spot scanning proton therapy system and measured the luminescence images of these phantoms with a high-sensitivity, cooled charge coupled device camera during proton-beam irradiation. The authors imaged the phantoms of pure water, fluorescein solution, and an acrylic block. Results: The luminescence images of water phantoms taken during proton-beam irradiation showed clear Bragg peaks, and the measured proton ranges from the images were almost the same as those obtained with an ionization chamber. Furthermore, the image of the pure-water phantom showed almost the same distribution as the tap-water phantom, indicating that the luminescence image was not related to impurities in the water. The luminescence image of the fluorescein solution had ∼3 times higher intensity than water, with the same proton range as that of water. The luminescence image of the acrylic phantom had a 14.5% shorter proton range than that of water; the proton range in the acrylic phantom generally matched the calculated value. The luminescence images of the tap-water phantom during proton irradiation could be obtained in less than 2 s. Conclusions: Luminescence imaging during proton-beam irradiation is promising as an effective method for range estimation in proton therapy.

  14. Calculated electronic energy loss of swift proton and helium ion beams in liquid water

    OpenAIRE

    Abril Sánchez, Isabel; García Molina, Rafael; Denton Zanello, Cristian D.; Emfietzoglou, Dimitris

    2008-01-01

    The electronic energy loss of swift proton and helium beams in liquid water is theoretically evaluated. Our model is based in the dielectric formalism, taking into account the charge exchange of the projectile during its travel through the target. The electronic properties of liquid water are described by the MELF-GOS model, where the outer electron excitations are represented by a sum of Mermin functions fitted to the experimental data in the optical limit, whereas the inner-shell electron e...

  15. Modeling of reverberation in shallow-water based on the beam tracing theory

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A reverberation intensity model and a reverberation series model in shallow-water based on the beam tracing theory were presented.The brief theoretical deduction to compute reverberation intensity was given,and the results were compatible with the measured data. The reverberation series simulation method was built and its characteristics were tested with the measured data and other results that had been verified.The studies show that the reverberation intensity model can be used to forecast shallow-water...

  16. Solvent extraction of niobium cations with products of nitrobenzene radiolysis

    International Nuclear Information System (INIS)

    Radiolysis of nitrobenzene solution of cobalt(III) dicarbollide, which is used for solvent extraction of cesium from fission products results in enhanced extraction of 95Nb. The isomeric nitrophenols, 2,4-dinitrophenol, p-nitrosophenol and m-aminophenol exhibit antergism towards extraction of niobium cations. Synergistic effect is exhibited by 2,5-dinitrophenol, o-and p-aminophenol, o-nitroaniline and 2,4,6-trinitrophenol which are among the products of two-phase systems with nitrobenzene radiolysis. Two competing processes, complexation of niobium and protonation of ligand, both depending on the ligand benzene ring substituents are discussed. (author) 15 refs.; 4 tabs

  17. Radiolysis of hydrazine-containing solution for bubbling depressurization systems

    International Nuclear Information System (INIS)

    Radiolysis was studied in an aqueous solution containing boric acid and hydrazine, as used in nuclear power plants for trapping volatile chemical forms of iodine during loss-of-coolant accidents. The parameters examined included changes in the hydrazine concentration and pH, and formation of radiolysis products in dependence on the initial hydrazine concentration, absorbed dose, dose rate and temperature. The loss of hydrazine and formation of products were compared for the static and through-flow irradiation modes. The results indicate that the radiation resistance of the solution decreases with its increasing oxygen content and with decreasing dose rate. (author). 4 figs., 17 refs

  18. Radiolysis of berberine or palmatine in aqueous solution

    Science.gov (United States)

    Marszalek, Milena; Wolszczak, Marian

    2011-01-01

    The reactions of hydrated electron (eaq-), hydrogen atom (H rad ) (reducing species) and Cl2•-, Br2•-, N,O•H radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of eaq- and rad OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with eaq- and radicals generated during radiolysis are unstable and undergo further reactions.

  19. Reaction mechanisms in the radiolysis of peptides, polypeptides and proteins

    International Nuclear Information System (INIS)

    The purpose of this review is to bring together and to correlate the wide variety of experimental studies that provide information on the reaction products and reaction mechanisms involved in the radiolysis of peptides, polypeptides and proteins (including chromosomal proteins) in both aqueous and solid-state systems. The comparative radiation chemistry of these systems is developed in terms of specific reactions of the peptide main-chain and the aliphatic, aromatic-unsaturated and sulfur-containing side-chains. Information obtained with the various experimental techniques of product analysis, competition kinetics, spin-trapping, pulse radiolysis and ESR spectroscopy is included. 147 refs

  20. Radiolysis of carboxylic acids adsorbed in clay minerals

    International Nuclear Information System (INIS)

    This research is aimed at studying the effect of ionizing radiation in an heterogeneous system formed by a carboxylic acid adsorbed in a clay mineral. The study is focussed to discriminate if the presence of a solid surface alters the formation and distribution of radiolytic products in relation to the radiolysis of the carboxylic acid without the surface (clay). The results showed that the radiolysis of the system clay-acid goes along a defined path rather than showing various pathways of decomposition as in the case of simple aqueous solutions. The main pathway was the decarboxylation of the target compound rather than condensation/dimerization reactions

  1. Reaction mechanisms in the radiolysis of peptides, polypeptides and proteins

    Energy Technology Data Exchange (ETDEWEB)

    Garrison, W.M.

    1985-01-01

    The purpose of this review is to bring together and to correlate the wide variety of experimental studies that provide information on the reaction products and reaction mechanisms involved in the radiolysis of peptides, polypeptides and proteins (including chromosomal proteins) in both aqueous and solid-state systems. The comparative radiation chemistry of these systems is developed in terms of specific reactions of the peptide main-chain and the aliphatic, aromatic-unsaturated and sulfur-containing side-chains. Information obtained with the various experimental techniques of product analysis, competition kinetics, spin-trapping, pulse radiolysis and ESR spectroscopy is included. 147 refs.

  2. The analysis of radiolysis products in meats and meat substances

    International Nuclear Information System (INIS)

    Analytical studies of the compounds formed during irradiation of meat have formed a major part of the United States National Food Irradiation Programme for more than 20 years. The author reviews the mechanisms of radiolysis and summarizes the principle products formed in meats upon irradiation. Of particular significance is the demonstrated dependency of radiolysis product formed upon parameters such as irradiation dose, temperature and food composition. This dependency permits a prediction of the radiolytic products likely to be formed in other irradiated foods of known chemical composition and hence reduces the need for individual wholesomeness testing of every food. (orig./MG)

  3. Nuclear halo of a 177\\,MeV proton beam in water

    CERN Document Server

    Gottschalk, Bernard; Daartz, Juliane; Wagner, Miles S

    2014-01-01

    The dose distribution of a pencil beam in a water tank consists of a core, a halo and an aura. The core consists of primary protons which suffer multiple Coulomb scattering (MCS) and slow down by multiple collisions with atomic electrons (Bethe-Bloch theory). The halo consists of charged secondaries, many of them protons, from elastic interactions with H, elastic and inelastic interactions with O, and nonelastic interactions with O. We show that the halo radius is roughly one third of the beam range. The aura consists of neutral secondaries (neutrons and gamma rays) and the charged particles they set in motion. We have measured the core/halo at 177 MeV using a test beam offset in a water tank. The beam monitor was a plane parallel ionization chamber (IC) and the field IC a dose calibrated Exradin T1. Our dose measurements are absolute. We took depth-dose scans at ten displacements from the beam axis ranging from 0 to 10 cm. The dose spans five orders of magnitude, and the transition from halo to aura is obvio...

  4. Single-beam water vapor detection system with automatic photoelectric conversion gain control

    Science.gov (United States)

    Zhu, C. G.; Chang, J.; Wang, P. P.; Wang, Q.; Wei, W.; Liu, Z.; Zhang, S. S.

    2014-11-01

    A single-beam optical sensor system with automatic photoelectric conversion gain control is proposed for doing high reliability water vapor detection under relatively rough environmental conditions. Comparing to a dual-beam system, it can distinguish the finer photocurrent variations caused by the optical power drift and provide timely compensation by automatically adjusting the photoelectric conversion gain. This system can be rarely affected by the optical power drift caused by fluctuating ambient temperature or variation of fiber bending loss. The deviation of the single-beam system is below 1.11% when photocurrent decays due to fiber bending loss for bending radius of 5 mm, which is obviously lower than the dual-beam system (8.82%). We also demonstrate the long-term stability of the single-beam system by monitoring a 660 ppm by volume (ppmv) water vapor sample continuously for 24 h. The maximum deviation of the measured concentration during the whole testing period does not exceed 10 ppmv. Experiments have shown that the new system features better reliability and is more apt for remote sensing application which is often subject to light transmission loss.

  5. TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop: FY-2012 Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Dean R. Peterman; Lonnie G. Olson; Richard D. Tillotson; Rocklan G. McDowell; Jack D. Law

    2012-09-01

    The INL radiolysis test loop has been used to evaluate the affect of radiolytic degradation upon the efficacy of the strip section of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. The nominal composition of the TRUEX solvent used in this study is 0.2 M CMPO and 1.4 M TBP dissolved in n-dodecane and the nominal composition of the TRUEX strip solution is 1.5 M lactic acid and 0.050 M diethylenetriaminepentaacetic acid. Gamma irradiation of a mixture of TRUEX process solvent and stripping solution in the test loop does not adversely impact flowsheet performance as measured by stripping americium ratios. The observed increase in americium stripping distribution ratios with increasing absorbed dose indicates the radiolytic production of organic soluble degradation compounds.

  6. Summary of TRUEX Radiolysis Testing Using the INL Radiolysis Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Dean R. Peterman; Lonnie G. Olson; Rocklan G. McDowell; Gracy Elias; Jack D. Law

    2012-03-01

    The INL radiolysis and hydrolysis test loop has been used to evaluate the effects of hydrolytic and radiolytic degradation upon the efficacy of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. Repeated irradiation and subsequent re-conditioning cycles did result in a significant decrease in the concentration of the TBP and CMPO extractants in the TRUEX solvent and a corresponding decrease in americium and europium extraction distributions. However, the build-up of solvent degradation products upon {gamma}-irradiation, had little impact upon the efficiency of the stripping section of the TRUEX flowsheet. Operation of the TRUEX flowsheet would require careful monitoring to ensure extraction distributions are maintained at acceptable levels.

  7. Inversion for sound speed profile in shallow water using matched-beam processing

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhongbing; MA Yuanliang; YANG Kunde; YAN Shefeng

    2004-01-01

    To quickly obtain the sound speed profile (SSP) in shallow water by inversion methods, an inversion scheme for SSP in shallow water using matched-beam processing (MBI) is developed. The cost function of MBI is based on matched-beam concept. It is verified experimentally that MBI is feasible and superior in comparison to conventional matched-field inversion (MFI) by using the East China Sea Experiment data. The SSP inverted by MBI using the wide-band explosion signals is in good agreement with the results measured based on conductivity, temperature and depth (CTD) in the experiment. And the root of mean square error of the inverted SSP is less than 2 m/s. Research results have shown that MBI is robust with respect to the sediment parameters mismatch. And SSP in shallow water can be more quickly obtained by MBI than by MFI.

  8. Testing Thermo-acoustic Sound Generation in Water with Proton and Laser Beams

    CERN Document Server

    Graf, K; Hoessl, J; Kappes, A; Karg, T; Katz, U; Lahmann, R; Naumann, C; Salomon, K; Stegmann, C

    2005-01-01

    Experiments were performed at a proton accelerator and an infrared laser acility to investigate the sound generation caused by the energy deposition of pulsed particle and laser beams in water. The beams with an energy range of 1 PeV to 400 PeV per proton beam spill and up to 10 EeV for the laser pulse were dumped into a water volume and the resulting acoustic signals were recorded with pressure sensitive sensors. Measurements were performed at varying pulse energies, sensor positions, beam diameters and temperatures. The data is well described by simulations based on the thermo-acoustic model. This implies that the primary mechanism for sound generation by the energy deposition of particles propagating in water is the local heating of the media giving rise to an expansion or contraction of the medium resulting in a pressure pulse with bipolar shape. A possible application of this effect would be the acoustical detection of neutrinos with energies greater than 1 EeV.

  9. Comparison of the secondary electrons produced by proton and electron beams in water

    Science.gov (United States)

    Kia, Mohammad Reza; Noshad, Houshyar

    2016-05-01

    The secondary electrons produced in water by electron and proton beams are compared with each other. The total ionization cross section (TICS) for an electron impact in water is obtained by using the binary-encounter-Bethe model. Hence, an empirical equation based on two adjustable fitting parameters is presented to determine the TICS for proton impact in media. In order to calculate the projectile trajectory, a set of stochastic differential equations based on the inelastic collision, elastic scattering, and bremsstrahlung emission are used. In accordance with the projectile trajectory, the depth dose deposition, electron energy loss distribution in a certain depth, and secondary electrons produced in water are calculated. The obtained results for the depth dose deposition and energy loss distribution in certain depth for electron and proton beams with various incident energies in media are in excellent agreement with the reported experimental data. The difference between the profiles for the depth dose deposition and production of secondary electrons for a proton beam can be ignored approximately. But, these profiles for an electron beam are completely different due to the effect of elastic scattering on electron trajectory.

  10. Effect of gamma and electron beam irradiation on textile waste water

    International Nuclear Information System (INIS)

    In this studies gamma and electron beam irradiation was used to treat textile waste water. Comparisons between both types of irradiation in terms of effectiveness to degrade the pollutants present in textile waste water were done. Prior to irradiation, the raw wastewater was diluted using distilled water to a target concentration of COD 400 mg/ l. The sample was irradiated at selected doses between the ranges of 10 kGy to 100 kGy. The results showed that irradiation has significantly contributed in the reduction of the highly colored refractory organic pollutants. The COD removal at the lowest dose, 10 kGy was reduced to 390 mg/ l for gamma and 400 mg/ l for electron beam. Meanwhile, at the highest dose, 100 kGy, the COD was reduced to 125 mg/ l for gamma and 144 mg/ l for electron beam. The degree of removal is influenced by the dose introduced during the treatment process. As the dose increased, the higher the removal of organic pollutant was recorded. However, gamma irradiation is more effective although the differences are not significant between gamma and electron beam irradiation. On the other hand, other properties of the wastewater such as pH, turbidity, suspended solid, BOD and color also shows a gradual decrease as the dose increases for both types of irradiation. (author)

  11. Effect of Gamma and Electron Beam Irradiation on Textile Waste Water

    International Nuclear Information System (INIS)

    In this studies gamma and electron beam irradiation was used to treat textile waste water. Comparisons between both types of irradiation in terms of effectiveness to degrade the pollutants present in textile waste water was done. Prior to irradiation, the raw wastewater was diluted using distilled water to a target concentration of COD 400 mg/l. The sample was irradiated at selected doses between the ranges of 10 kGy to 100 kGy. The results showed that irradiation has significantly contributed in the reduction of the highly colored refractory organic pollutants. The COD removal at the lowest dose, 10 kGy, was reduced to 390 mg/l for gamma and 400 mg/l for electron beam. Meanwhile, at the highest dose, 100 kGy, the COD was reduced to 125 mg/l for gamma and 144 mg/l for electron beam. The degree of removal is influenced by the dose introduced during the treatment process. As the dose increased, the higher the removal of organic pollutant was recorded. However, gamma irradiation is more effective although the differences are not significant between gamma and electron beam irradiation. On the other hand, other properties of the wastewater such as pH, turbidity, suspended solid, BOD and color also shows a gradual decrease as the dose increases for both types of irradiation. (author)

  12. Hydrated Electrons in a Quaternary Microemulsion System: A Pulse Radiolysis Study

    Science.gov (United States)

    Adhikari; Joshi; Gopinathan

    1997-07-01

    Using the technique of pulse radiolysis, hydrated electrons have been produced and studied in quaternary microemulsion (sodium lauryl sulfate (NaLS)/water/cyclohexane/1-pentanol) system. Remarkably high lifetimes ( approximately 20 &mgr;s) for hydrated electrons have been obtained. In general, these are two orders of magnitude higher than those reported earlier in reverse micelles. The water droplet sizes and location of the probes have been determined from the decay kinetics of hydrated electrons. The yields and half-lives (t 1/2 ) of the hydrated electrons vary smoothly as the water droplet sizes are changed. We believe that these studies will be useful not only in interpreting electron transfer reactions occurring in small water pockets in biological systems but also in the production of metal nanoclusters by radiation chemical method. PMID:9241228

  13. Two step formation of metal aggregates by surface X-ray radiolysis under Langmuir monolayers: 2D followed by 3D growth

    Directory of Open Access Journals (Sweden)

    Smita Mukherjee

    2015-12-01

    Full Text Available In order to form a nanostructured metallic layer below a Langmuir monolayer, radiolysis synthesis was carried out in an adapted geometry that we call surface X-ray radiolysis. In this procedure, an X-ray beam produced by a synchrotron beamline intercepts the surface of an aqueous metal-ion solution covered by a Langmuir monolayer at an angle of incidence below the critical angle for total internal reflection. Underneath the organic layer, the X-ray beam induces the radiolytic synthesis of a nanostructured metal–organic layer whose ultrathin thickness is defined by the vertical X-ray penetration depth. We have shown that increasing the X-ray flux on the surface, which considerably enhances the kinetics of the silver layer formation, results in a second growth regime of silver nanocrystals. Here the formation of the oriented thin layer is followed by the appearance of a 3D powder of silver clusters.

  14. High-energy irradiation treatment of aqueous solutions of C.I. Reactive Black 5 azo dye: pulse radiolysis experiments

    International Nuclear Information System (INIS)

    The reactions of the C.I. Reactive Black 5 with short lived eaq-, OH radical and H atom intermediates of water radiolysis in aqueous solution were investigated by pulse radiolysis with kinetic spectroscopic detection. The transients formed with the three intermediates have absorption maxima at ∼360, ∼410 and ∼470 nm. The eaq- adds to the azo group and the adduct radical anion rapidly protonates forming hydrazil radical. Based on the similar spectra similar intermediates are produced in H atom and hydrated electron reaction. The OH radical most probably adds to the azo group, however, it attacks also the aromatic rings. The strong absorbance found is attributed to the high conjugation of the radical site with the aromatic rings

  15. Effect of radiolysis on long-term corrosion system formed on low-alloy steels

    International Nuclear Information System (INIS)

    In France, for nuclear waste management, it is planned to build a storage device with a barrier system composed of steel container. Corrosion is evaluated for the safety of anoxic storage over the long term. With radiation, water radiolysis generates oxidizing and reducing species that can change the corrosion. Three aspects are developed in this thesis. The first concerns iron coupon samples experimented in carbonate deaerated water and subjected to gamma irradiation. It is shown that irradiation can increase corrosion rates within the parameters of dose. Identified crystalline phases are little changed with irradiation. Solution chemistry shows a decrease in pH with dose related to iron. Organic species are identified. The second axis is archaeological analogues irradiation with an old corrosion products layer. Structural analysis verified the phase stability with radiolysis, only the newly formed products changes. The third axis is a kinetic simulation approach. It checks the pH drop under irradiation. Taken together, these results allow us to provide new data for the anoxic corrosion under irradiation. (author)

  16. Protection in radiolysis of n-hexadecane: Pt. 2

    International Nuclear Information System (INIS)

    Protection effect of aromatic (naphthalene, phenanthrene) and hydroaromatic (tetralin, octahydrophenanthrene) compounds in irradiated liquid alkane has been investigated as a model experiment for the radiolysis of polymers. Liquid n-hexadecane has been selected as the model linear amorphous polymer and the protection effect has been studied by analyzing the radiolysis products. In the presence of additives, degradation of n-hexadecane, reduction of radiolysis products, including H2 evolution, and selective degradation of the additive have been observed. Energy transfer (excitation and charge) to the additive reduces the solvent excitation which is the precursor or the radiolysis products. The additive reacts with the solvent molecules according to its reactivity to form adduct compounds. Mass analysis shows that these adduct compounds have a smaller number of double bonds in their aromatic rings due to hydrogenation. Aromatic compounds are more reactive than hydroaromatic compounds towards n-hexadecane and their adducts consume more hydrogen than those of the hydroaromatic compounds, and therefore aromatic compounds reduce gas formation more effectively than hydroaromatic compounds. From the effect of aromatic compounds, it is concluded that hexadecene is produced neither by H2 elimination from the lowest excited state of n-hexadecane nor by disproportionation of n-hexadexyl radicals, but is mainly produced directly from the decomposition of the excited cations of n-hexadecane. (Author)

  17. Experimental and theoretical study of the coagulation of radiolysis aerosols

    International Nuclear Information System (INIS)

    The processing of concentration measurement upstream and downstream of a diffusion battery to obtain the particle size distribution of an aerosol is first described. The uni- and bi-modal size distribution of an aerosol generated by radiolysis of atmospheric gaseous impurities has been then determined. The experimental data have been compared with the data supplied by numerical resolution of the coagulation equation

  18. Pico second pulse radiolysis experimental technique and some results

    International Nuclear Information System (INIS)

    Pico second pulse radiolysis of aqueous systems is described starting from the initial experiments of Hunt. The pico second work at the Argonne National Laboratory is described along with the chemical and electronic problems encountered. The present status is described with suggestions for improvement in instrumentation which can lead to a better understanding of the primary processes in irradiated aqueous systems. (auth.)

  19. Leach and radiolysis data for FUETAP concretes containing SRP wastes

    International Nuclear Information System (INIS)

    This supplement to ORNL/TM-8579 contains experimental results for leach tests and alpha-radiolysis tests made on FUETAP concretes containing Savannah River Plant waste. The results, presented in two sections, consist of both the raw data and calculated values for individual experiments. This information is summarized and analyzed in Sections 5 and 7 of ORNL/TM-8579

  20. [Pulsed radiolysis of aqueous solutions of serum albumin containing naphthoquinones].

    Science.gov (United States)

    Pribush, A G; Savich, A V

    1987-01-01

    As was shown by the pulse radiolysis method the simultaneous presence of naphthoquinone and human serum albumin molecules in an aqueous solution leads to the adsorption of the former on the surface of the latter. It is suggested that in these conditions the protein tertiary structure changes. New conformation reduces the reactivity of albumin toward the hydrated electron. PMID:3628723

  1. Pulse radiolysis with (sub) nanosecond time resolution using a 3 MV electron accelerator

    International Nuclear Information System (INIS)

    In this thesis the development of equipment for pulse radiolysis is described and the application of the technique to time-resolved measurements of the fluorescence emission of excited states formed after irradiation of some alkanes is dealt with. A review is given of the development of the pulsed 3MV Van de Graaf electron accelerator for the generation of subnanosecond electron beam pulses and of the development of the equipment for optical detection as accomplished by the author. The initial stage of a further development for shorter pulses and higher time resolution is briefly discussed. A collection of papers on the development of apparatus and a collection of papers dealing with the results obtained from measurements of the fluorescence of excited states, formed by the recombination of electrons and ions in irradiated alkanes such as cyclohexane and the decalines, are included. (Auth.)

  2. The effect of temperature on radiolysis of iodide ion diluted aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Gorbovitskaya, T.; Tiliks, J. [Latvia Univ., Lab. of Radiation Chemistry, Riga (Latvia)

    1996-12-01

    To investigate the radiolysis of iodine containing aqueous solutions a flow type facility (ITF) has a possibility to irradiate aqueous solutions in the steel vessel with {sup 60}Co {gamma}-rays and continuously (on line) to analyze the products of radiolysis both in liquid and in gaseous phases. By means of ITF the formation of I{sub ox} (I{sub 2} + I{sub 3}{sup -} + HOI), IO{sub 3}{sup -}, H{sub 2}O{sub 2} was studied in 10{sup -5} - 10{sup -3} mol/dm{sup 3} CsI aqueous solutions by their radiolysis at dose rate 4.5 kGv/h for six hours in region of temperatures from 313 to 404 K. Some experiments in glass ampoules were also performed. The steady-state concentrations of I{sub ox} and IO{sub 3}{sup -} decreased with increasing temperature as linear function of inverted temperature. The effect decreased with decreasing concentration of iodide ion. As the result, at high temperatures (T{>=}380 K) the steady-state concentration of I{sub ox} does not depend essentially on the iodide ion initial concentration. Molecular iodine (I{sub 2}) released from the solution was the main radiolysis product in gaseous phase. Its steady-state concentration increased with increasing temperature because of iodine solubility in the water and decreased at the same time because the radiolytic iodine concentrations decreased. Therefore the most volatility of irradiated 10{sup -3} and 10{sup -4}M CsI solutions was observed at the temperature about 350 K. The volatility of 10{sup -5}M solutions gradually decreased with increasing temperature. The experimental data were explained on the base of the hypothesis that the reaction between I{sub 2} and radiolytic H{sub 2}O{sub 2} was the limit one determining the temperature dependence of I{sub ox} and IO{sub 3}{sup -}steady-state concentrations. Its activation energy was estimated to be 27,5 kcal.mol{sup -1}. The temperature dependence for reaction (IO{sup -} + H{sub 2}O{sub 2}) was also estimated. (author) 8 figs., 1 tab., 17 refs.

  3. Nuclear halo of a 177 MeV proton beam in water: theory, measurement and parameterization

    CERN Document Server

    Gottschalk, Bernard; Daartz, Juliane; Wagner, Miles S

    2014-01-01

    The dose distribution of a monoenergetic pencil beam in water consists of an electromagnetic "core", a "halo" from charged nuclear secondaries, and a much larger "aura" from neutral secondaries. These regions overlap, but each has distinct spatial characteristics. We have measured the core/halo using a 177MeV test beam offset in a water tank. The beam monitor was a fluence calibrated plane parallel ionization chamber (IC) and the field chamber, a dose calibrated Exradin T1, so the dose measurements are absolute (MeV/g/p). We performed depth-dose scans at ten displacements from the beam axis ranging from 0 to 10cm. The dose spans five orders of magnitude, and the transition from halo to aura is clearly visible. We have performed model-dependent (MD) and model-independent (MI) fits to the data. The MD fit separates the dose into core, elastic/inelastic nuclear, nonelastic nuclear and aura terms, and achieves a global rms measurement/fit ratio of 15%. The MI fit uses cubic splines and the same ratio is 9%. We re...

  4. Added mass matrix estimation of beams partially immersed in water using measured dynamic responses

    Science.gov (United States)

    Liu, Fushun; Li, Huajun; Qin, Hongde; Liang, Bingchen

    2014-09-01

    An added mass matrix estimation method for beams partially immersed in water is proposed that employs dynamic responses, which are measured when the structure is in water and in air. Discrepancies such as mass and stiffness matrices between the finite element model (FEM) and real structure could be separated from the added mass of water by a series of correction factors, which means that the mass and stiffness of the FEM and the added mass of water could be estimated simultaneously. Compared with traditional methods, the estimated added mass correction factors of our approach will not be limited to be constant when FEM or the environment of the structure changed, meaning that the proposed method could reflect the influence of changes such as water depth, current, and so on. The greatest improvement is that the proposed method could estimate added mass of water without involving any water-related assumptions because all water influences are reflected in measured dynamic responses of the structure in water. A five degrees-of-freedom (dofs) mass-spring system is used to study the performance of the proposed scheme. The numerical results indicate that mass, stiffness, and added mass correction factors could be estimated accurately when noise-free measurements are used. Even when the first two modes are measured under the 5 percent corruption level, the added mass could be estimated properly. A steel cantilever beam with a rectangular section in a water tank at Ocean University of China was also employed to study the added mass influence on modal parameter identification and to investigate the performance of the proposed method. The experimental results demonstrated that the first two modal frequencies and mode shapes of the updated model match well with the measured values by combining the estimated added mass in the initial FEM.

  5. Design of a high pressure system for pulse radiolysis studies up to 400 MPa with flow regulation

    Science.gov (United States)

    NGuyen Le, D.-T.; Pin, S.; Anjoure, D.; Chopineau, P.; Baldacchino, G.

    2013-03-01

    This article reports details of a new setup including an optical flow cell and devices which can increase pressure up to 400 MPa by controlling the ramp rate. It is composed of two high pressure syringe pumps which can make liquids flowing up to 4 cm3/mn. The optical flow cell can contains aqueous solutions and allow carry out pulse radiolysis experiments with a pulsed 10-MeV electron beam by performing in situ and time resolved optical analysis, such as transient UV-visible absorption or fluorescence spectroscopy. A Labview-program has been developed to drive and monitor automatons which regulate pressure, make solution flow under pressure, carry out operations such as filling, emptying or cleaning the system under safe conditions. Two results are exhibited: 1/associated to phosphate buffer, the fluorescence spectrum of the fluorescein pH-sensor has been performed under pressure. Phosphate pKa is confirmed to be very sensitive to pressure increase even up to 300 MPa. 2/a time-resolved absorption spectroscopy of hydrated electron in deaerated water has been conducted up to 350 MPa with a continuous flow of sample. In presence of tertio-butanol and bisTris pH7-buffer in solution, the spectral shift of hydrated electron is finely reproduced. BisTris is also confirmed as insensitive buffer under high pressure and its reduction by hydrated electron remains constant with a rate constant of (4.6 ± 0.6) × 108 M-1 s-1.

  6. Fabrication of an oil-water separation copper filter using laser beam machining

    Science.gov (United States)

    Ha, Kyoung Ho; Chu, Chong Nam

    2016-04-01

    In this study, oil and water are successfully separated using a copper filter that is fabricated using only laser beam machining. Even though copper is hydrophilic and recast copper material, which inevitably results during laser beam machining, is super-hydrophilic, the filter can prevent the water from penetrating and allow oil to flow based on surface tension of the liquids at the hole exit. For practical uses of the filter, both the pressure differences at which the filter is able to retain its ability to separate and the oil penetration rate of the filter are revealed. The fabrication process is simple and time-saving, and the filter has high durability because of lack of surface coating or surface chemical modification.

  7. DYNAMICS OF IONIZATION-ENHANCED SPECTRAL EXPANSION IN WATER INDUCED BY AN INTENSE FEMTOSECOND LASER BEAM

    Institute of Scientific and Technical Information of China (English)

    WANG SHU-FENG; QIN YUAN-DONG; YANG HONG; WANG DAN-LING; ZHU CHANG-JUN; GONG QI-HUANG

    2001-01-01

    The dynamic process of white-continuum generation in water was investigated by the pump-probe technique with a femtosecond intense laser at 805nm. The spectrum width of the probe beam was broadened at the blue side and varied with different delay times. This blueshift was attributed to the ionization-enhanced optical nonlinearity, in which both the multi-photon ionization and avalanche ionization had an effect.

  8. Water soluble and metal-containing electron beam resist poly(sodium 4-styrenesulfonate)

    International Nuclear Information System (INIS)

    Popular electron beam resists such as PMMA, ZEP and HSQ all use solvent or base solutions for processing, which may attack the sub-layers or substrate that are made out of organic semiconducting materials. In this study we show that water soluble poly(sodium 4-styrenesulfonate), or sodium PSS, can be used as a negative electron beam resist developed in water. Moreover, since PSS contains metal sodium, its dry etching resistance is much higher than PMMA. It is notable that sodium PSS’s sensitivity and contrast is still far inferior to organic resists such as PMMA, thus it is not suitable for patterning dense and high-resolution structures. Nevertheless, feature size down to 40 nm was achieved for sparse patterns. Lastly, using very low energy (here 2 keV) electron beam lithography and liftoff process using water only, patterning of metal layer on an organic conductive material P3HT was achieved. The metallization of an organic conducting material may find applications in organic semiconductor devices such as OLED. (paper)

  9. Geant4 Simulation Study of Dose Distribution and Energy Straggling for Proton and Carbon Ion Beams in Water

    Directory of Open Access Journals (Sweden)

    Zhao Qiang

    2016-01-01

    Full Text Available Dose distribution and energy straggling for proton and carbon ion beams in water are investigated by using a hadrontherapy model based on the Geant4 toolkit. By gridding water phantom in N×N×N voxels along X, Y and Z axes, irradiation dose distribution in all the voxels is calculated. Results indicate that carbon ion beams have more advantages than proton beams. Proton beams have bigger width of the Bragg peak and broader lateral dose distribution than carbon ion beams for the same position of Bragg peaks. Carbon ion has a higher local ionization density and produces more secondary electrons than proton, so carbon ion beams can achieve a higher value of relative biological effectiveness.

  10. Treatment of ships' ballast water by irradiation of pulsed, intense relativistic electron beam

    International Nuclear Information System (INIS)

    Zooplankton contained in ships' ballast water has been successfully treated by irradiation of pulsed, intense relativistic electron beam (PIREB). A treatment chamber is filled up with solution of 3-wt% salt in water containing a larva of artemia as the zooplankton, and is irradiated by the PIREB (2 MeV, 0.4 kA, 140 ns). We have found that electric conductivity and pH of the salt solution does not change significantly within 10 shots of the PIREB irradiation. We have obtained that the artemia of 24% is inactivated by firing 10 shots of the PIREB irradiation. (author)

  11. Effects of thermal conduction and convection on temperature profile in a water calorimeter for proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Gargioni, E.; Manfredotti, C. [Torino Univ. (Italy). Dipt. di Fisica; Laitano, R.F.; Guerra, A.S. [Ist. Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA, Roma (Italy)

    1997-09-01

    In water calorimetry, in addition to the temperature increase due to beam energy deposition in water, unwanted thermal effects occur during and after calorimeter irradiation. This should be accounted for by applying proper corrections to the experimental results. In order to determine such corrections heat flow calculations were performed using the `finite element` method. This method applies even to complex 3D geometries with not necessarily symmetric conditions. Some preliminary results of these calculations are presented together with a description of the analytical method for the evaluation of the correction factors that should be applied to the experimental results to account for the above thermal effects. (orig.)

  12. Ozone/electron beam process for water treatment: design, limitations and economic considerations

    International Nuclear Information System (INIS)

    Electron beam irradiation of water is the easiest way to generate OH free radicals but the efficiency of the irradiation process as advanced oxidation process (AOP) is deteriorated by reducing species formed simultaneously with the OH free radicals. Addition of ozone to the water before or during irradiation improves the efficiency essentially by converting the reducing species into OH free radicals and turning by that the irradiation process into a full AOP. The main reaction pathways of the primary species formed by the action of ionizing radiation on water in a natural groundwater with and without the presence of ozone are reviewed. Based on these data an explanation of both the dose rate effect and the ozone effect is attempted. New data is presented which illustrates the effect of alkalinity on the way in which ozone is introduced into the water, and the impact of both water matrix and chemical structure of the pollutants to the efficacy of the ozone/electron beam process. (author)

  13. Sputtering and Chemical Modification of Solid Surfaces by Water Cluster Ion Beams

    International Nuclear Information System (INIS)

    Water was introduced into a cluster source, and heated up to 150 deg. C by a wire heater attached around the source. When the vapor pressure was larger than 1 atm, the vaporized water clusters were produced by an adiabatic expansion. The irradiation effects of water cluster ions on solid surfaces such as Si(100) and Ti substrates were investigated. The sputtered depth increased with increase of ion dose and acceleration voltage. The sputtering yield of the Si and Ti surfaces by the water cluster ion beams was approximately 10 times larger than that by Ar monomer ion beams at the same acceleration voltage. In addition, the XPS measurement showed that the sputtered surface had an oxide layer such as SiOx and TiOx. It was found from the depth profile of O1s peak that the oxide layer thickness increased with increase of acceleration voltage, and it was about 10 nm at an acceleration voltage of 6 kV. Furthermore, the contact angles for the sputtered surfaces were measured, and they were about 80 degrees for the Ti surfaces and about 5 degrees for the Si surfaces, respectively. The contact angle for the unirradiated surface was about 45 degrees for Si surface and about 30 degrees for Ti surface, and the change of the contact angles was due to the oxide layer formation by the water cluster ion irradiation

  14. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    International Nuclear Information System (INIS)

    Full text: The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters using 60Co γ radiation, ten X-ray beam qualities between TPR20,10=0.639 and 0.802 and ten electron beam qualities between R50=1.75 gcm-2 and 8.54 gcm-2. A 22 MeV microtron accelerator with a conventional treatment head is used as radiation source for the high energy photon and electron beams. The treatment head produces clinical beams. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter of the Domen type, that is used to calibrate several METAS transfer standards of type NE2611A and NE2571A in terms of absorbed dose to water in the energy range from 60Co to TPR20,10 = 0.802. User reference dosimeters are compared with the transfer standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co γ radiation and 1.4% for higher energies (coverage factor k=2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the Code of Practice of the International Atomic Energy Agency using the calculated kQ factors listed in table 14. The comparison showed a maximum difference of 0.8% for the NE25611A and NE 2571A chambers. At 60Co γ radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau International des Poids et Mesures BIPM (Sevres) as well as of the National Research Council NRC (Canada). In either case the standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of precisely known particle energy and beam charge is totally absorbed in Fricke solution (ferrous ammonium sulphate) of a given mass. This

  15. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    International Nuclear Information System (INIS)

    The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters. The calibration service uses 60Co gamma radiation, ten high energy photon beam qualities between TPR20,10 = 0.639 and 0.802 and ten electron beam qualities between R50 = 1.75 g/cm2 and 8.54 g/cm2. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter used to calibrate several METAS NE 2611A and NE 2571A type ionization chamber working standards in terms of absorbed dose to water in the energy range of 60Co to TPR20,10 = 0.802. The users' reference dosimeters are compared with the working standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co radiation and 1.4% for higher energies (coverage factor k = 2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the IAEA Technical Reports Series No. 398 (TRS 398) code of practice and from Recommendations No. 4 of the Swiss Society of Radiobiology and Medical Physics (SSRMP). The comparisons showed a maximum difference of 1.2% for the NE 2561A and NE 2571A chambers. At 60Co gamma radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau international des poids et mesures.The standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of known particle energy and beam charge is totally absorbed in Fricke solution. The experiment was carried out in the energy range of 5.3 MeV to 22.4 MeV, which allows the determination of the response of the Fricke dosimeter. Finally, the users' dosimeters are compared with the METAS working standards. The overall uncertainty in

  16. Molecular mechanisms induced by the effects of ionizing radiation on nucleic acids: Free radicals in 5-halogenated uracil derivatives after reaction of radiolysis products of water in low-temperature glass

    International Nuclear Information System (INIS)

    This thesis deals with the molecular mechanisms induced by the effects of ionizing radiation on the DNA. The study has been made for the main purpose of clarifying the possible role of the indirect effect, namely the attack of diffusible water radicals, in the process of radiosensitivity enhancement due to the incorporation of bromouracil instead of thymine into the DNA. The results of the experiments can be summarized by the statement that among the reactions studied in the low-temperature glasses, none revealed such a clear difference between uracil and thymine on the one hand, and the halogenated uracils on the other, that this difference could suffice to explain in terms of quality and quantity the observed in-vivo enhancement of radiosensitivity by halogenated uracils. This conclusion is in agreement with the results of radiobiological measurements on phagae and bacteria which in all cases revealed no or only very slight enhancement of the radiosensitivity in the indirect effect subsequent to bromouracil incorporation. (orig./AJ)

  17. Relations between oxygen and hydrogen generated by radiolysis in the systems of a CANDU 600

    International Nuclear Information System (INIS)

    The water that constitutes the coolant of the primary heat transport system, the moderator and the liquid control zones, decomposed under radiation producing as stable products oxygen, hydrogen and hydrogen peroxide throughout a complex mechanisms of radiolysis that involves ions and free radicals. These compound formed in different proportions alters the chemical control established for each system which purpose is to minimize the corrosion of the structural materials. In the present paper have been presented results of the modelling of the mentioned processes and it has been found that in the absence of a vapor phase, a relatively low concentration of hydrogen added to the water would be sufficient to control the formation of oxygen and hydrogen peroxide. The last species however, would remain in relatively high values inside a coolant fuel channel in the reactor core. (author)

  18. The effects of radiolysis on the corrosion and stress corrosion behavior of 316 stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Duquette, D.J.; Steiner, D.

    1993-09-01

    This program is focused on the corrosion, stress corrosion and corrosion fatigue behavior of Type 316 stainless steel (316SS) at 50, 90, and 130 C in high-purity water. Irradiated solution tests are performed using high-energy photon radiation. Purpose of this work is to determine the effects of radiolysis products on the environmental stability of 316SS in support of the ITER first wall/shield/blanket design. Preliminary results suggest that irradiation of pure water at 50 C results in a shift in the electrochemical potential for 316SS of approximately 100mV in the active direction and nearly an order of magnitude increase in the passive current density as compared to non-irradiated conditions. This proposal outlines a three-year program to develop corrosion design criteria for the use of 316SS in an ITER environment.

  19. Appliance of Electron Beam Technology for Disinfection of Sewage Water to Minimize Public Health Risks

    Directory of Open Access Journals (Sweden)

    S. Sabharwal

    2013-06-01

    Full Text Available First time in India, a study was aimed to establish a base- line data for electron beamradiation dose level needed to disinfect and also improve the water quality of sewage waterfor possible reuse in irrigation, industries as well as a few domestic purposes. Raw andsecondary treated sewage water samples, which were rich with microorganisms from NaviMumbai municipal sewage plant were irradiated with electron beam accelerator at doses of0.45, 0.75, 1.5, 3.0, 4.5, 6.0, 7.5, 9.0 and 10.5 kGy. Electron Beam irradiation treatment ofthe wastewater was found to be very effective in reducing the pathogenic load. ElectronBeam (EB dose of 1.5 kGy was sufficient for complete elimination of total coli formswhereas Cryptococcus laurentii, Aspergillus fumigatus and Absidia sp. were killedby10.0 kGy and no larvae of helminthes (Ascaris lumbricoides were recovered at thedose ≥ 1.5 kGy. The experimental findings obtained highlighted the potential of thistechnology for disinfection of wastewater.

  20. Primary processes in radiation chemistry. LET (Linear Energy Transfer) effect in water radiolysis; Processus primaires en chimie sous rayonnement. Influence du transfert d'energie lineique sur la radiolyse de l'eau

    Energy Technology Data Exchange (ETDEWEB)

    Trupin-Wasselin, V

    2000-07-11

    The effect of ionizing radiations on aqueous solutions leads to water ionization and then to the formation of radical species and molecular products (e{sup -}{sub aq}, H{sup .}, OH{sup .}, H{sub 2}O{sub 2}, H{sub 2}). It has been shown that the stopping power, characterized by the LET value (Linear Energy Transfer) becomes different when the nature of the ionizing radiations is different. Few data are nowadays available for high LET radiations such as protons and high energy heavy ions. These particles have been used to better understand the primary processes in radiation chemistry. The yield of a chemical dosimeter (the Fricke dosimeter) and those of the hydrogen peroxide have been determined for different LET. The effect of the dose rate on the Fricke dosimeter yield and on the H{sub 2}O{sub 2} yield has been studied too. When the dose rate increases, an increase of the molecular products yield is observed. At very high dose rate, this yield decreases on account of the attack of the molecular products by radicals. The H{sub 2}O{sub 2} yield in alkaline medium decreases when the pH reaches 12. This decrease can be explained by a slowing down of the H{sub 2}O{sub 2} formation velocity in alkaline medium. Superoxide radical has also been studied in this work. A new detection method: the time-resolved chemiluminescence has been perfected for this radical. This technique is more sensitive than the absorption spectroscopy. Experiments with heavy ions have allowed to determine the O{sub 2}{sup .-} yield directly in the irradiation cell. The experimental results have been compared with those obtained with a Monte Carlo simulation code. (O.M.)

  1. Electron-transfer reactions between viologen radical cations and quinones in AOT reverse micelles studied by electron pulse radiolysis

    International Nuclear Information System (INIS)

    Electron-transfer reactions between viologen radical cations (CnVsm-bullet+, n = 1-18) and various quinones have been studied in aqueous and reverse micellar (AOT/isooctane/H2O) solution by use of the electron pulse radiolysis technique. By use of dynamic light scattering measurements, the concentration of water pools was determined and the number of electron-transfer reactants per water pool could be calculated. Rate constants measured for the reaction between CnVsm-bullet+ radicals and anthraquinonesulfonate ions (AQS-) decreased with increasing length of the aliphatic chain of the viologens, caused by association of the viologen with the surfactant interface

  2. Characterization of the water-equivalent material WTe for use in electron beam dosimetry

    Science.gov (United States)

    McEwen, M. R.; Du Sautoy, A. R.

    2003-07-01

    This paper describes the characterization of the water-equivalent material WTe (produced by St Bartholomew's Hospital, London). The use of epoxy resin phantoms offers a number of advantages over water for radiotherapy dosimetry in terms of robustness and ease of use, but the published uncertainties in the fluence corrections for such phantoms significantly increase the overall uncertainty in the measurement of absorbed dose to water at the reference point. Depth-ionization data were obtained in water and WTe for electron beams in the range 4 MeV to 16 MeV and it was found that the measured fluence in the WTe phantom was approximately 0.4% higher than in a water phantom at the same depth. For measurements only at the reference depth this difference was less, with the fluence in the WTe phantom being 0.2% higher. The standard uncertainty on this value is estimated to be +/-0.12%, which represents a significant improvement over previous measurements. It was also found that the range scaling factor is not equal to unity, as previously recommended for this material, but that the data was best fitted by the relation 1 mm WTe = 1.01 mm water (with an uncertainty of +/-0.2%). The results obtained confirm previous investigations of WTe as to its suitability for reference ion chamber dosimetry in the radiotherapy clinic. However, the recommendation is still to use a water phantom wherever possible.

  3. Characterization of the water-equivalent material WTe for use in electron beam dosimetry

    International Nuclear Information System (INIS)

    This paper describes the characterization of the water-equivalent material WTe (produced by St Bartholomew's Hospital, London). The use of epoxy resin phantoms offers a number of advantages over water for radiotherapy dosimetry in terms of robustness and ease of use, but the published uncertainties in the fluence corrections for such phantoms significantly increase the overall uncertainty in the measurement of absorbed dose to water at the reference point. Depth-ionization data were obtained in water and WTe for electron beams in the range 4 MeV to 16 MeV and it was found that the measured fluence in the WTe phantom was approximately 0.4% higher than in a water phantom at the same depth. For measurements only at the reference depth this difference was less, with the fluence in the WTe phantom being 0.2% higher. The standard uncertainty on this value is estimated to be ±0.12%, which represents a significant improvement over previous measurements. It was also found that the range scaling factor is not equal to unity, as previously recommended for this material, but that the data was best fitted by the relation 1 mm WTe = 1.01 mm water (with an uncertainty of ±0.2%). The results obtained confirm previous investigations of WTe as to its suitability for reference ion chamber dosimetry in the radiotherapy clinic. However, the recommendation is still to use a water phantom wherever possible

  4. A water-cooled x-ray monochromator for using off-axis undulator beam

    International Nuclear Information System (INIS)

    Undulator beamlines at third-generation synchrotrons x-ray sources are designed to use the high-brilliance radiation that is contained in the central cone of the generated x-ray beams. The rest of the x-ray beam is often unused. Moreover, in some cases, such as in the zone-plate-based microfocusing beamlines, only a small part of the central radiation cone around the optical axis is used. In this paper, a side-station branch line at the Advanced Photon Source that takes advantage of some of the unused off-axis photons in a microfocusing x-ray beamline is described. Detailed information on the design and analysis of a high-heat-load water-cooled monochromator developed for this beamline is provided

  5. Removal of diclofenac from surface water by electron beam irradiation combined with a biological aerated filter

    Science.gov (United States)

    He, Shijun; Wang, Jianlong; Ye, Longfei; Zhang, Youxue; Yu, Jiang

    2014-12-01

    The degradation of DCF was investigated in aqueous solution by using electron beam (EB) technology. When the initial concentration was between 10 and 40 mg/L, almost 100% of the DCF was degraded at a dose of 0.5 kGy. However, only about 6.5% of DCF was mineralized even at 2 kGy according to total organic carbon (TOC) measurements. A combined process of EB and biological aerated filter (BAF) was therefore developed to enhance the treatment of DCF contaminated surface water. The effluent quality of combined process was substantially improved by EB pretreatment due to the degradation of DCF and related intermediates. Both irradiation and biological treatment reduced the toxicity of the treated water. The experimental results showed that EB is effective for removing DCF from artificial aqueous solution and real surface water.

  6. Pumping experiment of water on B and LaB6 films with electron beam evaporator

    International Nuclear Information System (INIS)

    Pumping characteristics of water vapor on boron and lanthanum hexaboride films formed with an electron beam evaporator have been investigated in high vacuum of a pressure region between 10-4 and 10-3 Pa. Measured initial maximum pumping speeds of water for fresh B and LaB6 films on substrates with a deposition amount from 2.3 x 1021 to 6.7 x 1021 molecules·m-2 are 3.2 ∼ 4.9 m3·s-1·m-2, and maximum saturation amounts of adsorbed water on these films are 2.9 x 1020 ∼ 1.3 x 1021 H2O molecules·m-2. (author)

  7. Radiolysis of TBP solutions in contact with nitric acid

    International Nuclear Information System (INIS)

    A study is made of the mechanisms of nitration and oxidation reactions in the sytem 25% tributyl phosphate + synthine + 3M HNO3. The influence of oxygen on yields of radiolysis products is demonstrated. The change-over from an oxygen-less solution to a solution compensated with 1 O2 atom results in an increase in the yield of oxygen-containing radiolysis products from 0.2 to 1.2 100 ev molecules, while the (RNO2+RNO) yield falls from 1.6 to 0.1 100 ev molecules. This explains certain discrepancies between these results and the findings of other authors. The supposition is advanced that not only hydrocarbons but also tributyl phosphate are involved in radiation nitration. (author)

  8. Radiolysis of berberine or palmatine in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Marszalek, Milena [Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland); Wolszczak, Marian, E-mail: marianwo@mitr.p.lodz.p [Institute of Applied Radiation Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland)

    2011-01-15

    The reactions of hydrated electron (e{sub aq}{sup -}), hydrogen atom (H{sup {center_dot}}) (reducing species) and Cl{sub 2}{sup {center_dot}}{sup -},Br{sub 2}{sup {center_dot}}{sup -},{sup {center_dot}}N{sub 3},{sup {center_dot}}OH radicals (oxidizing species) with berberine or palmatine in aqueous solution have been studied by steady-state and pulse radiolysis. The spectra of transient intermediates, leading to the final products, are presented. The rate constants of the reaction of e{sub aq}{sup -} and {sup {center_dot}}OH radical with both alkaloids in the homogenous solution and in the presence of DNA are reported. It is demonstrated that the primary products of the reaction of berberine and palmatine with e{sub aq}{sup -} and radicals generated during radiolysis are unstable and undergo further reactions.

  9. Radiolysis of actinides and technetium in alkaline media

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, C.H., Westinghouse Hanford

    1996-07-10

    The {gamma}-radiolysis of aerated alkaline aqueous solutions of Np(V), Np(VI), Pu(VI), Tc(IV), Tc(V), and TC(VII) was studied in the absence of additives and in the presence of CO{sub 3}{sup 2-}, NO{sub 3}{sup -}, NO{sub 2}{sup -}, EDTA, formate, and other organic compounds. The radiolytic reduction of Np(V), Np(VI), Pu(VI), and TC(VII) under different experimental conditions was examined in detail. The addition of EDTA, formate, and alcohols was found to considerably increase the radiation-chemical reduction yields. The formation of the Np(V) peroxo complex was observed in the {gamma}-radiolysis of alkaline aqueous solutions of Np (VI) in the presence of nitrate.

  10. Gamma-ray radiolysis of the FPEX solvent

    International Nuclear Information System (INIS)

    FPEX contains a calixarene for Cs extraction, a crown ether for Sr extraction, Cs7SB modifier and TOA to aid in stripping, all in Isopar L diluent. The radiation stability of FPEX must be evaluated prior to process use. The radiolytic degradation of species in solution is due to reaction with the direct radiolysis products of the diluent. In Isopar L, the reactive species produced include solvated electrons (e-), hydrogen atoms (H) and alkane radicals, resulting in a reducing environment. However, when contacted with nitric acid, oxidising hydroxyl (OH) and nitrous (NO2) radicals dominate the system chemistry. Thus, the nature of the diluent and the presence of radical scavengers affect the results of irradiation. We report the preliminary results of a new programme to investigate the radiolysis of FPEX using the 60Co irradiation of FPEX neat solvent, acid pre-equilibrated solvent and mixed aerated phases. The Cs and Sr distribution ratios were used as metrics. (authors)

  11. Radiolysis of chloramphenicol and its eye ointment during gamma sterilisation

    International Nuclear Information System (INIS)

    The effects of γ radiation sterilisation on chloramphenicol (CAP), both in pure powder state and in eye ointment, were investigated with high performance liquid chromatography (HPLC) and HPLC-MS. Five radiation degradation products were observed and identified, the radiolysis mechanisms were elucidated, and the application of γ radiation sterilisation on chloramphenicol was discussed. It has been determined that at irradiation dose of 25 kGy, the content of chloramphenicol decreases by 1.0% in powder state and by 3.3% in eye ointment. By comparing the radiolytic products of CAP in different matrices, it is concluded hydrolysis, oxidation and radical reduction are the main radiolytical degradation reactions of chloramphenicol, and the micro-environment surrounding chloramphenicol molecular plays an important role in the radiolysis process. Protection techniques to resist radiolyses are thus proposed based on the experimental findings. (author)

  12. On the nuclear halo of a proton pencil beam stopping in water

    Science.gov (United States)

    Gottschalk, Bernard; Cascio, Ethan W.; Daartz, Juliane; Wagner, Miles S.

    2015-07-01

    The dose distribution of a proton beam stopping in water has components due to basic physics and may have others from beam contamination. We propose the concise terms core for the primary beam, halo (see Pedroni et al 2005 Phys. Med. Biol. 50 541-61) for the low dose region from charged secondaries, aura for the low dose region from neutrals, and spray for beam contamination. We have measured the dose distribution in a water tank at 177 MeV under conditions where spray, therefore radial asymmetry, is negligible. We used an ADCL calibrated thimble chamber and a Faraday cup calibrated integral beam monitor so as to obtain immediately the absolute dose per proton. We took depth scans at fixed distances from the beam centroid rather than radial scans at fixed depths. That minimizes the signal range for each scan and better reveals the structure of the core and halo. Transitions from core to halo to aura are already discernible in the raw data. The halo has components attributable to coherent and incoherent nuclear reactions. Due to elastic and inelastic scattering by the nuclear force, the Bragg peak persists to radii larger than can be accounted for by Molière single scattering. The radius of the incoherent component, a dose bump around midrange, agrees with the kinematics of knockout reactions. We have fitted the data in two ways. The first is algebraic or model dependent (MD) as far as possible, and has 25 parameters. The second, using 2D cubic spline regression, is model independent. Optimal parameterization for treatment planning will probably be a hybrid of the two, and will of course require measurements at several incident energies. The MD fit to the core term resembles that of the PSI group (Pedroni et al 2005), which has been widely emulated. However, we replace their T(w), a mass stopping power which mixes electromagnetic (EM) and nuclear effects, with one that is purely EM, arguing that protons that do not undergo hard single scatters continue to lose

  13. On the nuclear halo of a proton pencil beam stopping in water.

    Science.gov (United States)

    Gottschalk, Bernard; Cascio, Ethan W; Daartz, Juliane; Wagner, Miles S

    2015-07-21

    The dose distribution of a proton beam stopping in water has components due to basic physics and may have others from beam contamination. We propose the concise terms core for the primary beam, halo (see Pedroni et al 2005 Phys. Med. Biol. 50 541-61) for the low dose region from charged secondaries, aura for the low dose region from neutrals, and spray for beam contamination. We have measured the dose distribution in a water tank at 177 MeV under conditions where spray, therefore radial asymmetry, is negligible. We used an ADCL calibrated thimble chamber and a Faraday cup calibrated integral beam monitor so as to obtain immediately the absolute dose per proton. We took depth scans at fixed distances from the beam centroid rather than radial scans at fixed depths. That minimizes the signal range for each scan and better reveals the structure of the core and halo. Transitions from core to halo to aura are already discernible in the raw data. The halo has components attributable to coherent and incoherent nuclear reactions. Due to elastic and inelastic scattering by the nuclear force, the Bragg peak persists to radii larger than can be accounted for by Molière single scattering. The radius of the incoherent component, a dose bump around midrange, agrees with the kinematics of knockout reactions. We have fitted the data in two ways. The first is algebraic or model dependent (MD) as far as possible, and has 25 parameters. The second, using 2D cubic spline regression, is model independent. Optimal parameterization for treatment planning will probably be a hybrid of the two, and will of course require measurements at several incident energies. The MD fit to the core term resembles that of the PSI group (Pedroni et al 2005), which has been widely emulated. However, we replace their T(w), a mass stopping power which mixes electromagnetic (EM) and nuclear effects, with one that is purely EM, arguing that protons that do not undergo hard single scatters continue to lose

  14. Pulse radiolysis of aqueous lignin solutions with acryl monomers

    International Nuclear Information System (INIS)

    Radiation-induced polymerization in aqueous solutions of methylmethacrylate and methylacrylate with and without lignin added was studied by pulse radiolysis method. Optical spectra of intermediates taking part in the chain evolution were obtained. The rate constant of the chain polymerization termination diminished when lignin added from 1.2 x 109 up to 2 x 108 mol-1 s-1. A reaction scheme of radiation-induced polymerization was proposed which included the lignin entering in chain propagation reactions. (author)

  15. γ-Irradiation-induced radiolysis of inulin in aqueous solutions

    International Nuclear Information System (INIS)

    Radiochemical transformations of inulin in aqueous solutions, in air, in the presence of inert gases, helium, nitrogen and in nitrous oxide exposed to various doses of 60Co γ-irradiation were investigated. It was shown that interactions in inulin with OH radicals are principally responsible for radiolytic decomposition of inulin. The data on radiolysis of more simple model systems were used to make available decomposition spectra of γ-irradiated aerated aqueous solution of inulin. 9 refs., 6 figs

  16. Pulse Radiolysis of Methyl Viologen in Aqueous Solutions

    DEFF Research Database (Denmark)

    Solar, S.; Solar, W.; Getoff, N.; Holcman, Jerzy; Sehested, Knud

    Pulse radiolysis of air-free aqueous methyl viologen (MV2+) solutions was carried out at various pH. The attack of e–aq on MV2+, with k(e–aq+ MV2+)= 7.5 × 1010 dm3 mol–1 s–1, leads to the formation of the long-lived radical cation (MV˙+), which possesses two absorption maxima at 392.5 nm (ε392...

  17. Radiolysis of methylene blue studied by ESR. [Gamma radiation

    Energy Technology Data Exchange (ETDEWEB)

    Contineau, M.; Iliescu, C.; Ciureanu, M. (National Inst. of Chemistry, Bucharest (RoO). Dept. of Physical Chemistry)

    1983-05-31

    Electron spin resonance spectra have been used to gain information on the mechanism of radiolysis of aqueous solutions of methylene blue. The identity and behaviour of the semiquinone radicals formed as intermediate reduction products were discussed for strongly acid and for alcaline solutions. In order to obtain information on the radiolytic mechanism in strongly acidic media, irradiation was performed in the presence of various types of scavengers: sodium formate, glucose, succinic acid, hydroquinone and D,L-..cap alpha.. alanine.

  18. Pulse Radiolysis of Adrenaline in Acid Aqueous Solutions

    DEFF Research Database (Denmark)

    Gohn, M.; Getoff, N.; Bjergbakke, Erling

    1976-01-01

    Pulse radiolysis of adrenaline in acid aqueous solutions (pH 1–3) was carried out. The rate constants for the reactions of adrenaline with H and OH were determined: k(H + adr.) = (0·9±0·1) × 109 dm3 mol−1s−1; k(OH + adr.) = (1·65±0·15) × 1010 dm3 mol−1s−1. The H-adduct of adrenaline has two λmax...

  19. A pulse radiolysis study on electron affinity of piperonal

    Institute of Scientific and Technical Information of China (English)

    MA; Jianhua; LIN; Weizhen; WANG; Wenfeng; YAO; Side

    2005-01-01

    The piperonal electron affinity was studied using pulse radiolysis technique. The electron transfer reaction process between piperonal and anthraquinone-2-sulfate was observed in the pH 7 phosphoric acid salt buffer. The transient absorption spectra of electron transfer reaction between piperonal and anthraquinone-2-sulfate were obtained, and the initial proof of the electron transfer between electron donor and acceptor was provided directly. The one-electron reduction potential of piperonal was determined to be -0.457 V.

  20. Nanosecond time-resolved EPR in pulse radiolysis via the spin echo method

    International Nuclear Information System (INIS)

    The design and operation of a time-resolved electron spin echo spectrometer suitable for detecting transient radicals produced by 3 MeV electron radiolysis is described. Two modes of operation are available: Field swept mode which generates a normal EPR spectrum and kinetic mode in which the time dependence of a single EPR line is monitored. Techniques which may be used to minimize the effects of nonideal microwave pulses and overlapping sample tube signals are described. The principal advantages of the spin echo method over other time-resolved EPR methods are: (1) Improved time resolution (presently approx.30--50 nsec) allows monitoring of fast changes in EPR signals of transient radicals, (2) Lower susceptibility to interference between the EPR signal and the electron beam pulse at short times, and (3) Lack of dependence of transient signals on microwave field amplitude or static field inhomogeneity at short times. The performance of the instrument is illustrated using CIDEP from acetate radical formed in pulsed radiolysis of aqueous solutions of potassium acetate. The relaxation time and CIDEP enhancement factor obtained for this radical using the spin echo method compare favorably with previous determinations using direct detection EPR. Radical decay rates yield estimates of initial radical concentrations of 10-410-3M per electron pulse. The Bloch equations are solved to give an expression for the echo signal for samples exhibiting CIDEP using arbitrary microwave pulse widths and distributions of Larmor frequencies. Conditions are discussed under which the time-dependent signal would be distorted by deviations from an ideal nonselective 900--tau--1800 pulse sequence

  1. Design, fabrication, installation and commissioning of water-cooled beam viewer for undulator front-ends of Indus-2

    International Nuclear Information System (INIS)

    A water-cooled beam viewer is developed indigenously to observe the bright synchrotron light coming from recently installed undulators in Indus-2 storage ring at RRCAT, Indore. The beam viewer is installed in the undulator front-end. The frontend is a long ultra high vacuum (UHV) assembly consisting of UHV valves, shutters, vacuum pumps and beam diagnostic devices. The front-end acts as an interface between Indus-2 ring and beamline. The beam viewer uses a fluorescent sheet of Chromium doped Alumina (CHROMOX) which produces visible fluorescent light when bright synchrotron light from the undulator falls on it. This visible fluorescent light is observed through a glass window by a CCD camera. The beam viewer has been successfully tested and commissioned in Indus-2 front-end for undulator. At present, the beam viewer is operating under vacuum of 5 x 10-10 mbar in the Indus-2 undulator front-end

  2. Influence of radiolysis on UO2 fuel matrix dissolution under disposal conditions. Literature Study

    International Nuclear Information System (INIS)

    The objective of this study was to examine the recent published literature on the influence of water radiolysis on UO2 fuel matrix dissolution under the disposal conditions. The α radiation is considered to be dominating over the other types of radiations at times longer than 1000 years. The presence of the anaerobic corrosion products of iron, especially of hydrogen, has been observed to play an important role under radiolysis conditions. It is not possible to exclude gamma/beta radiolysis effects in the experiments with spent fuel, since there is not available a fuel over 100 years old. More direct measurements of α radiolysis effects have been conducted with α doped UO2 materials. On the basis of the results of these experiments, a specific activity threshold to observe α radiolysis effects has been presented. The threshold is 1.8 x 107 to 3.3 x 107 Bq/g in anoxic 10-3 M carbonate solution. It is dependent on the environmental conditions, such as the reducing buffer capacity of the conditions. The results of dissolution rate measurements at VTT with 233 U-doped UO2 samples in 0.01 to 0.1 M NaCl solutions under anoxic conditions did not show any effect of α radiolysis with doping levels of 5 and 10% 233 U (3.2 x 107 and 6.3 x 107 Bq/g). Both Fe2+ and hydrogen can act as reducing species and could react with oxidizing radiolytic species. Fe2+ concentrations of the order of 10-5 M can decrease the rate of H2 O2 production. Low dissolution rates, 2 x 10-8 to 2 x 10-7 /yr, have been measured in the presence of metallic Fe with 5 and 10%233U-doped UO2 in 0.01 to 1 M NaCl solutions. The tests with isotope dilution method showed precipitation phenomena of U to occur during dissolution process. The concentrations of dissolved U were extremely low (≤ 8.4 x 10-11 M). No effects of -radiolysis could be seen. It is difficult to distinguish the effects of metallic Fe, Fe2+ or hydrogen in these tests. Hydrogen could also act as a reducing agent. Interaction tests

  3. Disinfection and reduction of organic load of sewage water by electron beam radiation

    Science.gov (United States)

    Maruthi, Y. Avasn; Das, N. Lakshmana; Hossain, Kaizar; Sarma, K. S. S.; Rawat, K. P.; Sabharwal, S.

    2011-09-01

    The efficacy of electron beam radiation for the disinfection and reduction of organic load of sewage water was assessed with ILU-6 Accelerator at Radiation Technology Development Division of the Bhabha Atomic Research Centre, Mumbai India. The current problem on environmental health in relation to water pollution insists for the safe disposal of sewage water. In general, sewage water comprises heterogeneous organic based chemicals as well as pathogens. EB treatment of the wastewater has found to be very effective in reducing the pathogens as well as organic load. EB dose of 1.5 kGy was sufficient for complete elimination of total coli forms. The experimental results elucidated the reduction of biological oxygen demand—BOD (35 and 51.7%) in both inlet and outlet sewage samples. Similarly reduction of chemical oxygen demand—COD was observed (37.54 and 52.32%) in both sewage samples with respect to increase in irradiation doses (0.45-6 kGy). The present study demonstrated the potential of ionizing radiation for disinfection of sewage and to increase the water quality of the wastewater by decreasing BOD and COD. So, the irradiation sewage water can find its application either in agriculture for irrigation, in industry for cooling purpose and some selected domestic purposes.

  4. On the nuclear halo of a proton pencil beam stopping in water

    OpenAIRE

    Gottschalk, Bernard; Cascio, Ethan W.; Daartz, Juliane; Wagner, Miles S.

    2014-01-01

    The dose distribution of a pencil beam in water consists of a core, a halo, an aura and (possibly) spray. The core is due to primary protons which suffer multiple Coulomb scattering (MCS) and slow down by multiple collisions with atomic electrons (Bethe-Bloch theory). The halo is due to charged secondaries, many of them protons, from elastic interactions with H, elastic and inelastic interactions with O, and nonelastic interactions with O. We show that the halo radius is roughly one third of ...

  5. Optical cone beam tomography of Cherenkov-mediated signals for fast 3D dosimetry of x-ray photon beams in water

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Adam K., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu; Andreozzi, Jacqueline M. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Zhang, Rongxiao [Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Pogue, Brian W., E-mail: Adam.K.Glaser@dartmouth.edu, E-mail: Brian.W.Pogue@dartmouth.edu [Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States); Gladstone, David J. [Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States)

    2015-07-15

    Purpose: To test the use of a three-dimensional (3D) optical cone beam computed tomography reconstruction algorithm, for estimation of the imparted 3D dose distribution from megavoltage photon beams in a water tank for quality assurance, by imaging the induced Cherenkov-excited fluorescence (CEF). Methods: An intensified charge-coupled device coupled to a standard nontelecentric camera lens was used to tomographically acquire two-dimensional (2D) projection images of CEF from a complex multileaf collimator (MLC) shaped 6 MV linear accelerator x-ray photon beam operating at a dose rate of 600 MU/min. The resulting projections were used to reconstruct the 3D CEF light distribution, a potential surrogate of imparted dose, using a Feldkamp–Davis–Kress cone beam back reconstruction algorithm. Finally, the reconstructed light distributions were compared to the expected dose values from one-dimensional diode scans, 2D film measurements, and the 3D distribution generated from the clinical Varian ECLIPSE treatment planning system using a gamma index analysis. A Monte Carlo derived correction was applied to the Cherenkov reconstructions to account for beam hardening artifacts. Results: 3D light volumes were successfully reconstructed over a 400 × 400 × 350 mm{sup 3} volume at a resolution of 1 mm. The Cherenkov reconstructions showed agreement with all comparative methods and were also able to recover both inter- and intra-MLC leaf leakage. Based upon a 3%/3 mm criterion, the experimental Cherenkov light measurements showed an 83%–99% pass fraction depending on the chosen threshold dose. Conclusions: The results from this study demonstrate the use of optical cone beam computed tomography using CEF for the profiling of the imparted dose distribution from large area megavoltage photon beams in water.

  6. Optical cone beam tomography of Cherenkov-mediated signals for fast 3D dosimetry of x-ray photon beams in water

    International Nuclear Information System (INIS)

    Purpose: To test the use of a three-dimensional (3D) optical cone beam computed tomography reconstruction algorithm, for estimation of the imparted 3D dose distribution from megavoltage photon beams in a water tank for quality assurance, by imaging the induced Cherenkov-excited fluorescence (CEF). Methods: An intensified charge-coupled device coupled to a standard nontelecentric camera lens was used to tomographically acquire two-dimensional (2D) projection images of CEF from a complex multileaf collimator (MLC) shaped 6 MV linear accelerator x-ray photon beam operating at a dose rate of 600 MU/min. The resulting projections were used to reconstruct the 3D CEF light distribution, a potential surrogate of imparted dose, using a Feldkamp–Davis–Kress cone beam back reconstruction algorithm. Finally, the reconstructed light distributions were compared to the expected dose values from one-dimensional diode scans, 2D film measurements, and the 3D distribution generated from the clinical Varian ECLIPSE treatment planning system using a gamma index analysis. A Monte Carlo derived correction was applied to the Cherenkov reconstructions to account for beam hardening artifacts. Results: 3D light volumes were successfully reconstructed over a 400 × 400 × 350 mm3 volume at a resolution of 1 mm. The Cherenkov reconstructions showed agreement with all comparative methods and were also able to recover both inter- and intra-MLC leaf leakage. Based upon a 3%/3 mm criterion, the experimental Cherenkov light measurements showed an 83%–99% pass fraction depending on the chosen threshold dose. Conclusions: The results from this study demonstrate the use of optical cone beam computed tomography using CEF for the profiling of the imparted dose distribution from large area megavoltage photon beams in water

  7. Biological systems: from water radiolysis to carbon ion radiotherapy

    Science.gov (United States)

    Beuve, Michael; Moreau, Jean-Michel; Rodriguez, Claire; Testa, Etienne

    2015-07-01

    Hadron therapy is an innovative cancer treatment method based on the acceleration of light ions at high energy. In addition to their interesting profile of dose deposition, which ensures accurate targeting of localized tumors, carbon ions offer biological properties that lead to an efficient treatment for radio- and chemo-resistant tumors and to provide a boost for tumors in hypoxia. This paper is a short review of the progress in theoretical, experimental, fundamental and applied research, aiming at understanding the origin of the biological benefits of light ions better. As a limit of such a vast and multidisciplinary domain, this review adopts the point of view of the physicists, leaning on results obtained in connection with CIMAP's IRRABAT platform.

  8. Pulse radiolysis study of imidazole and histidine in water

    International Nuclear Information System (INIS)

    The reaction rate constants of e-/sub aq/ and OH radicals with imidazole (ImH), N-methylimidazole (MeIm), histidine, and N-methylhistidine were determined. The k(e-/sub aq/ + S) values were strongly dependent on the state of protonation of the ''pyridine'' nitrogen in these molecules, with rates of approximately 5 x 109 M-1 sec-1 at pH approximately 6.0 and (approximately 1-2) x 107 M-1 sec-1 at pH approximately 10.0. The k(OH + S) values show only small but significant changes with pH with rates of approximately 5 x 109 M-1 sec-1 at pH 4 to 5 and approximately 9.0 x 109 M-1 sec-1 at pH 9 to 10. The transient absorption spectra of the e-/sub aq/ and OH radical adducts to these molecules were observed. For e-/sub aq/ addition to imidazole at pH approximately 5.0, the ImH2. radical suggested to be formed has maxima at 300 and 360 nm and epsilon300 5.6 x 103 M-1 cm-1; the MeImH. radical has maxima at 310 and 360 nm with epsilon360 6.1 x 103 M-1 cm-1. The OH radical adducts to ImH2+ and ImH have maxima at 295 and 400 nm and at 310 and 390 nm, respectively. A pK/sub a/(radical) = 6.1 is observed for the equilibrium OH.ImH2+ reversible OH.ImH + H+, which is close to pK/sub a/ = 7.1 for loss of a proton from the ''pyridine'' nitrogen of imidazole. The results from the OH radical adduct to N-methylimidazole support this assignment. Similar results wereobtained for histidine and N-methylhistidine. The decay kinetics of the free-radical intermediates were determined. (U.S.)

  9. Spectroscopic characterization of mechanisms of oxidation of Phe by SO4- radical: A pulse radiolysis study

    Institute of Scientific and Technical Information of China (English)

    储高升; 韩镇辉; 都志文; 张淑娟; 姚思德; 张志成

    2002-01-01

    By using time-resolved kinetic spectrophotometry and pulse radiolysis technique, the oxidation of Phe by SO4- radical has been investigated both in aqueous and water/acetonitrilemixed solutions. The results reveal that attack of the oxidizing SO4- radical on Phe leads directlyto the formation of Phe cation radical 3 with a strong absorption peak at 310 nm, then it proceeds in three competitive reactions via either hydroxylation, deprotonation or decarboxylation, which were found to be strongly dependent upon the ionization state of the substitutes -COOH and -NH2 and the nature of the solvents. Decarboxylation takes place only when the carboxyl group is deprotonated. At high pH deprotonation of Phe cation radical 3 is much easier to occur than that in neutral or acid solutions. Moreover, with addition of acetonitrile, deprotonation is more predominant than hydroxylation, whereas in aqueous solutions hydroxylation is much easier to occur.

  10. Spectroscopic characterization of mechanisms of oxidation of Phe by SO.-4 radical: A pulse radiolysis study

    Institute of Scientific and Technical Information of China (English)

    储高升; 张淑娟; 姚思德; 韩镇辉; 都志文; 张志成

    2002-01-01

    By using time-resolved kinetic spectrophotometry and pulse radiolysis technique, the oxidation of Phe by radical has been investigated both in aqueous and water/acetonitrile mixed solutions. The results reveal that attack of the oxidizing SO4-radical on Phe leads directly to the formation of Phe cation radical 3 with a strong absorption peak at 310 nm, then it proceeds in three competitive reactions via either hydroxylation, deprotonation or decarboxylation, which were found to be strongly dependent upon the ionization state of the substitutes -COOH and -NH2 and the nature of the solvents. Decarboxylation takes place only when the carboxyl group is deprotonated. At high pH deprotonation of Phe cation radical 3 is much easier to occur than that in neutral or acid solutions. Moreover, with addition of acetonitrile, deprotonation is more predominant than hydroxylation, whereas in aqueous solutions hydroxylation is much easier to occur.

  11. Production of oxidants from α-radiolysis in the South Devon deposit

    International Nuclear Information System (INIS)

    The maximum production of H2O2 caused by α-radiolysis of water in the close vicinity of uranium-containing nodules found at the South Devon site has been estimated. The integrated α-doses from decay of U-238 and U-235 from the time of mineralization until today have been calculated. Calculations have been carried out for three different times: 140, 170, and 240 Myear. The maximum production from one nodule (diameter 4 cm) under 240 Myear was estimated to be 0.075 mole H2O2 (= 2.5 g). For a number of causes, discussed in the report, the actual production will probably be much lower

  12. Development and application of a new ultra-fast pulse radiolysis system

    International Nuclear Information System (INIS)

    In order to investigate radiation induced fast phenomena, a new highly time-resolved pulse radiolysis system based on pulse and probe method has been developed combined with a Mg laser photocathode RF-gun and a femtosecond laser. It has been attained time resolution less than 10 ps, as well as enabled spectroscopy in wide wavelength covering from visible to infrared region. Accordingly, the system has been taken to determine the initial yields and time behaviors of pre-solvated and solvated electrons in water and variety of alcohols systematically in picosecond time range, and if necessary, to microsecond with help of a practical nanosecond technique (kinetic method). Besides the experiments, reconciliation of Monte-Carlo simulations with the new experimental yield of the hydrated electron was also done. (author)

  13. The radiolysis of tryptophan and leucine with P-32 beta-radiation

    International Nuclear Information System (INIS)

    The paper extends earlier experiments on the radiolysis of DL-tryptophan using P-32 beta-radiation to longer reaction times, observing complete destruction of tryptophan by secondary, nonradiolytic processes. In addition DL-leucine is irradiated with P-32 beta-irradiation at -196 C, leading to radiolyses to the extents of about 20-30%, but observing no concomitant asymmetric bias. The complete absence of asymmetric bias in the present and earlier (Bonner et al., 1979) radiolyses of aqueous tryptophan at -25 C and the present radiolyses of water-free leucine at -196 C using P-32 beta-radiation and its accompanying bremsstrahlung leave it an open question whether or not the Vester-Ulbricht beta-decay/bremsstrahlung mechanism for the origin of optical activity is a viable one

  14. The radiolysis of tryptophan and leucine with P-32 beta-radiation

    Science.gov (United States)

    Blair, N. E.; Bonner, W. A.

    1980-01-01

    The paper extends earlier experiments on the radiolysis of DL-tryptophan using P-32 beta-radiation to longer reaction times, observing complete destruction of tryptophan by secondary, nonradiolytic processes. In addition DL-leucine is irradiated with P-32 beta-irradiation at -196 C, leading to radiolyses to the extents of about 20-30%, but observing no concomitant asymmetric bias. The complete absence of asymmetric bias in the present and earlier (Bonner et al., 1979) radiolyses of aqueous tryptophan at -25 C and the present radiolyses of water-free leucine at -196 C using P-32 beta-radiation and its accompanying bremsstrahlung leave it an open question whether or not the Vester-Ulbricht beta-decay/bremsstrahlung mechanism for the origin of optical activity is a viable one.

  15. Stimulated Raman Scattering and Nonlinear Focusing of High-Power Laser Beams Propagating in Water

    CERN Document Server

    Hafizi, B; Penano, J R; Gordon, D F; Jones, T G; Helle, M H; Kaganovich, D

    2015-01-01

    The physical processes associated with propagation of a high-power (power > critical power for self-focusing) laser beam in water include nonlinear focusing, stimulated Raman scattering (SRS), optical breakdown and plasma formation. The interplay between nonlinear focusing and SRS is analyzed for cases where a significant portion of the pump power is channeled into the Stokes wave. Propagation simulations and an analytical model demonstrate that the Stokes wave can re-focus the pump wave after the power in the latter falls below the critical power. It is shown that this novel focusing mechanism is distinct from cross-phase focusing. While discussed here in the context of propagation in water, the gain-focusing phenomenon is general to any medium supporting nonlinear focusing and stimulated forward Raman scattering.

  16. Stimulated Raman scattering and nonlinear focusing of high-power laser beams propagating in water.

    Science.gov (United States)

    Hafizi, B; Palastro, J P; Peñano, J R; Gordon, D F; Jones, T G; Helle, M H; Kaganovich, D

    2015-04-01

    The physical processes associated with propagation of a high-power (power > critical power for self-focusing) laser beam in water include nonlinear focusing, stimulated Raman scattering (SRS), optical breakdown, and plasma formation. The interplay between nonlinear focusing and SRS is analyzed for cases where a significant portion of the pump power is channeled into the Stokes wave. Propagation simulations and an analytical model demonstrate that the Stokes wave can re-focus the pump wave after the power in the latter falls below the critical power. It is shown that this novel focusing mechanism is distinct from cross-phase focusing. The phenomenon of gain-focusing discussed here for propagation in water is expected to be of general occurrence applicable to any medium supporting nonlinear focusing and stimulated Raman scattering. PMID:25831383

  17. CGR MeV program for water and liquid sludges treatment with high-energy electron beams. Pt. 1

    International Nuclear Information System (INIS)

    Research on the application of high-energy electron beams treatment to water and liquid sludges is described. Topics discussed include limitations of conventional methods of water treatment, dosimetry, biological assays with Pleurodeles waltlii, radioactivity measurement, chemical and bacteriological analysis. (author)

  18. Dosimetric study of thermoluminescent detectors in clinical photon beams using liquid water and PMMA phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Matsushima, Luciana C., E-mail: lmatsushima@ipen.br [Gerencia de Metrologia das Radiacoes (GMR) - Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, CEP: 05508-000, Sao Paulo, SP (Brazil); Veneziani, Glauco R. [Gerencia de Metrologia das Radiacoes (GMR) - Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, CEP: 05508-000, Sao Paulo, SP (Brazil); Sakuraba, Roberto K. [Gerencia de Metrologia das Radiacoes (GMR) - Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, CEP: 05508-000, Sao Paulo, SP (Brazil); Sociedade Beneficente Israelita Brasileira - Hospital Albert Einstein (HAE), Avenida Albert Einstein, 665, Morumbi, CEP: 05652-000, Sao Paulo, SP (Brazil); Cruz, Jose C. da [Sociedade Beneficente Israelita Brasileira - Hospital Albert Einstein (HAE), Avenida Albert Einstein, 665, Morumbi, CEP: 05652-000, Sao Paulo, SP (Brazil)

    2012-07-15

    The purpose of this study was the dosimetric evaluation of thermoluminescent detectors of calcium sulphate doped with dysprosium (CaSO{sub 4}:Dy) produced by IPEN compared to the TL response of lithium fluoride doped with magnesium and titanium (LiF:Mg,Ti) dosimeters and microdosimeters produced by Harshaw Chemical Company to clinical photon beams dosimetry (6 and 15 MV) using liquid water and PMMA phantoms. - Highlights: Black-Right-Pointing-Pointer Dosimetric study of thermoluminescent detectors of CaSO{sub 4}:Dy, LiF:Mg,Ti and {mu}LiF:Mg,Ti. Black-Right-Pointing-Pointer Clinical (6 and 15 MV) photon beams dosimetry using liquid water and PMMA phantom. Black-Right-Pointing-Pointer Linear behavior to the dose range (0.1 to 5 Gy). Black-Right-Pointing-Pointer TL response reproducibility better than {+-}4.34%. Black-Right-Pointing-Pointer CaSO{sub 4}:Dy represent a cheaper alternative to the TLD-100.

  19. Electron beam irradiation enhances the digestibility and fermentation yield of water-soaked lignocellulosic biomass

    Directory of Open Access Journals (Sweden)

    Jin Seop Bak

    2014-12-01

    Full Text Available In order to overcome the limitation of commercial electron beam irradiation (EBI, lignocellulosic rice straw (RS was pretreated using water soaking-based electron beam irradiation (WEBI. This environment-friendly pretreatment, without the formation (or release of inhibitory compounds (especially hydroxymethylfurfural and furfural, significantly increased the enzymatic hydrolysis and fermentation yields of RS. Specifically, when water-soaked RS (solid:liquid ratio of 100% was treated with WEBI doses of 1 MeV at 80 kGy, 0.12 mA, the glucose yield after 120 h of hydrolysis was 70.4% of the theoretical maximum. This value was predominantly higher than the 29.5% and 52.1% measured from untreated and EBI-treated RS, respectively. Furthermore, after simultaneous saccharification and fermentation for 48 h, the ethanol concentration, production yield, and productivity were 9.3 g/L, 57.0% of the theoretical maximum, and 0.19 g/L h, respectively. Finally, scanning electron microscopy images revealed that WEBI induced significant ultrastructural changes to the surface of lignocellulosic fibers.

  20. Pulse radiolysis and steady-state analyses of the reaction between hydroethidine and superoxide and other oxidants

    OpenAIRE

    Zielonka, Jacek; Sarna, Tadeusz; Roberts, Joan E.; Wishart, James F.; Kalyanaraman, B.

    2006-01-01

    Hydroethidine (HE) is a cell-permeable probe used for the intracellular detection of superoxide. Here we report the direct measurement of the rate constant between hydroethidine and superoxide radical anion using the pulse radiolysis technique. This reaction rate constant was calculated to be ca. 2·106 M-1s-1 in water:ethanol (1:1) mixture. The spectral characteristics of the intermediates indicated that the one-electron oxidation product of HE was different from the one-electron reduction pr...

  1. Experimental design approach for identification of the factors influencing the γ-radiolysis of ion exchange resins

    International Nuclear Information System (INIS)

    Gamma radiolysis was investigated on a nuclear grade mixed bed ion exchange resin and its pure components under different irradiation conditions. Screening designs were performed to identify the factors influencing gas production after their γ-radiolysis and to compare their γ-degradation stability. Only hydrogen and trimethylamine quantities were considered as the response in the experimental designs. The other detected gases and water-soluble products were used to improve the resins degradation. Aerobic irradiation atmosphere decreased the H2g production of AmbOH, MB400, and amines. The water presence increased the H2g quantities for AmbH and decreased those for MB400 resin. Liquid water had no effect on H2g production from AmbOH but was favorable to increased amine production. The H2g production of AmbH increased with the absorbed dose that had little effect on the AmbOH resin. No impact of dose on the H2g production was detected for MB400 that appeared to be less degraded. - Highlights: • Ion exchange resins were irradiated under different conditions. • Resins degradation was studied from the gases and water-soluble products analyses. • A screening design allowed identifying the factors influencing gases production. • The resins gamma stability was estimated from the response of experimental designs. • A reaction scheme was proposed for each resin degraded under different conditions

  2. Production of HCl and H2 in the radiolysis of PVC

    International Nuclear Information System (INIS)

    Complete text of publication follows. PVC is a thermoplastic polymer commonly encountered in nuclear waste management, disposition and disposal. The effects of ionising radiation on its performance are insufficiently understood. Our study has focused on the postirradiation degradation of γ and 4He ion irradiated PVC and on the release of potentially corrosive and explosive gases, such as HCl and H2, from deaerated, aerated, and water mixtures of PVC. Experiments were performed with PVC powder samples with number average weight of 22000 D and with unplasticised PVC film. The samples were irradiated with 60Co γ-rays and 4He ions at room temperature. The production and post-irradiation release of HCl and H2 was measured using ion and gas chromatography, respectively. The post-irradiation evolution of the solid plastic was examined using GPC and EPR, FT-IR and UV/VIS spectroscopy. UV/VIS absorbance spectroscopy was performed on PVC powder dissolved in THF. FT-IR transmittance spectra were obtained from PVC powder in air. EPR spectra were taken after γ-irradiation of PVC powders in air and vacuum, and for PVC film irradiated with γ-rays and 4He ions. GPC measurements were made on both pure and irradiated PVC powder and PVC film. The yield of HCl from γ-radiolysis of PVC powder is 19.6 molecules/100 eV. Chloride ion is released from the polymer for days following radiolysis. The H2 yield with γ-rays is about 0.23 molecule/100 eV and 0.45 molecule/100 eV with 4He ion radiolysis. Visually, irradiated PVC samples change from white to a green-brown colour with the extent of discolouration dependent on the applied dose and irradiation environment. No significant post-irradiation evolution of the chromophores was observed by FT-IR or UV/VIS, but the EPR spectra obtained evolve with time. GPC analysis showed a molecular weight distribution with a smaller mean in the irradiated samples compared to pure PVC. This change is related to HCl loss and possibly to main chain

  3. In-phantom measurement of absorbed dose to water in medium energy x-ray beams

    International Nuclear Information System (INIS)

    Absorbed dose values in a water phantom derived by the formalism of the IAEA Code of Practice of Absorbed Dose Determination in Photon and Electron Beams are a few per cent higher than those based on the procedure following e.g. ICRU Report 23. The maximum deviation exceeds 10% at 100 kV tube potential. The correction factor needed to take into account the differences at the calibration in terms of air kerma free in air and at the measurement in the water phantom can be determined in different ways: In comparing the result of the absorbed dose measurement by means of the ionization chambers with an other, preferably fundamental method of measurement of absorbed dose in the water phantom or by evaluating all component parts of the correction factor separately. The values of the perturbation correction factor in the IAEA Code were determined in the former way by comparing against a graphite extrapolation chamber. A review is given on a recent re-evaluation using former values of the extrapolation chamber measurements and on new determinations using an absorbed dose water calorimeter, a method based on calculated and measured air kerma values and a method of combining the component factors to the overall correction factor. Recent results achieved by the different methods are compared and a change of the data of the IAEA Code is recommended. (author). 31 refs, 14 figs, 3 tabs

  4. The international protocol for the dosimetry of external radiotherapy beams based on standards of absorbed dose to water

    International Nuclear Information System (INIS)

    An International Code of Practice (CoP, or dosimetry protocol) for external beam radiotherapy dosimetry based on standards of absorbed dose to water has been published by the IAEA on behalf of IAEA, WHO, PAHO and ESTRO. The CoP provides a systematic and internationally unified approach for the determination of the absorbed dose to water in reference conditions with radiotherapy beams. The development of absorbed-dose-to-water standards for high-energy photons and electrons offers the possibility of reducing the uncertainty in the dosimetry of radiotherapy beams. Many laboratories already provide calibrations at the radiation quality of 60Co gamma-rays and some have extended calibrations to high-energy photon and electron beams. The dosimetry of kilovoltage x-rays, as well as that of proton and ion beams can also be based on these standards. Thus, a coherent dosimetry system based on the same formalism is achieved for practically all radiotherapy beams. The practical use of the CoP as simple. The document is formed by a set of different CoPs for each radiation type, which include detailed procedures and worksheets. All CoPs are based on ND,w chamber calibrations at a reference beam quality Qo, together with radiation beam quality correction factors kQ preferably measured directly for the user's chamber in a standards laboratory. Calculated values of kQ are provided together with their uncertainty estimates. Beam quality specifiers are 60Co, TPR20,10 (high-energy photons), R50 (electrons), HVL and kV (x-rays) and Rres (protons and ions)

  5. Possible interactions of vapor-radiolysis with the oxidation of zirconium by steam

    International Nuclear Information System (INIS)

    An interaction of the zirconium oxidation process with the radiolysis of steam is discussed. The conclusion is drawn that a great deal of experimentation is necessary to determine whether the radiolysis of superheated vapor triggers the zirconium oxidation at elevated temperatures in a manner that would result in a considerable decrease of the temperature necessary to create a self-sustaining exothermic reaction

  6. Degradation of naphthalene and fluorene by radiolysis using accelerated electrons; Degradacion de naftaleno y fluoreno por radiolisis empleando electrones acelerados

    Energy Technology Data Exchange (ETDEWEB)

    Flores de Jesus, I

    2003-07-01

    The volume of the dangerous wastes in global level is causing the poisoning of planet and all of the ecosystems, degrading the life level of millions of humans and causing serious problems in the public health. Since a years ago the volumes of organic effluents generated by the few industry and small populations were so tiny that a natural debugger process in a time and space delimited, acquiring again their natural characteristics and they could be used again. Nowadays these wastes are so numerous and precise in some cases that the capacity of natural purification in the receiving channel is not enough, in addition to the difficulty to treat them in conventional processes, this leads to the decrease in the water's quality making impossible its future use and causing with this a serious ecological problem. This fact has motivated the development of measures that tend to the conservation of the environment and in consequence, the development of debugger technologies with no generation of sub products that often are more dangerous than the originals, due to the previous thing, the treatment by means of radiation of the water is impelled since is a method that allows to degrade or to eliminate in simultaneous form pathogenic microorganisms and organic substances. The radiation by means of electrons beams is a method of advanced treatment who allows to degrade organic compounds, transforming them in compounds with less molecular weight, and in the best of the cases until its oxidation to carbon dioxide and water. In the present thesis the objective is the study of naphthalene and fluorene degradation by means of radiation with electron beams, establishing the operating conditions of the accelerator of Pelletron type. This research is supported by the Instituto Nacional de Investigaciones Nucleares, of a joint way with a series of antecedents in this subject, established in previous research with respect to the treatment of residual waters in a great scale, giving

  7. Electron Beam-Induced Immobilization of Laccase on Porous Supports for Waste Water Treatment Applications

    Directory of Open Access Journals (Sweden)

    Elham Jahangiri

    2014-08-01

    Full Text Available The versatile oxidase enzyme laccase was immobilized on porous supports such as polymer membranes and cryogels with a view of using such biocatalysts in bioreactors aiming at the degradation of environmental pollutants in wastewater. Besides a large surface area for supporting the biocatalyst, the aforementioned porous systems also offer the possibility for simultaneous filtration applications in wastewater treatment. Herein a “green” water-based, initiator-free, and straightforward route to highly reactive membrane and cryogel-based bioreactors is presented, where laccase was immobilized onto the porous polymer supports using a water-based electron beam-initiated grafting reaction. In a second approach, the laccase redox mediators 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS and syringaldehyde were cross-linked instead of the enzyme via electron irradiation in a frozen aqueous poly(acrylate mixture in a one pot set-up, yielding a mechanical stable macroporous cryogel with interconnected pores ranging from 10 to 50 µm in size. The membranes as well as the cryogels were characterized regarding their morphology, chemical composition, and catalytic activity. The reactivity towards waste- water pollutants was demonstrated by the degradation of the model compound bisphenol A (BPA. Both membrane- and cryogel-immobilized laccase remained highly active after electron beam irradiation. Apparent specific BPA removal rates were higher for cryogel- than for membrane-immobilized and free laccase, whereas membrane-immobilized laccase was more stable with respect to maintenance of enzymatic activity and prevention of enzyme leakage from the carrier than cryogel-immobilized laccase. Cryogel-immobilized redox mediators remained functional in accelerating the laccase-catalyzed BPA degradation, and especially ABTS was found to act more efficiently in immobilized than in freely dissolved state.

  8. (n, γ)-radiolysis of magnesium iodate

    International Nuclear Information System (INIS)

    The initial retention of thermal neutron irradiated magnesium iodate tetrahydrate was found to be 47% and increased to 54% for the dehydrated salt. The post irradiation isothermal annealing followed the characteristic pattern both in hydrated and dehydrated salts; the rate of increase in retention in the hydrated salt being faster than in the dehydrated form. At an annealing temperature of 453 K, 100% retention was achieved by the hydrated salt but the corresponding value for the dehydrated magnesium iodate was not higher than 88%. The role of water of crystallization in the retention studies of magnesium iodate is discussed. (author)

  9. Impacts of Continuous Electron Beam Accelerator Facility operations on groundwater and surface water: Appendix 9

    International Nuclear Information System (INIS)

    The operation of the proposed Continuous Electron Beam Accelerator Facility (CEBAF) at Newport News, Virginia, is expected to result in the activation and subsequent contamination of water resources in the vicinity of the accelerator. Since the proposed site is located in the headwaters of the watershed supplying Big Bethel Reservoir, concern has been expressed about possible contamination of water resources used for consumption. Data characterizing the surface water and groundwater regime in the site area are limited. A preliminary geotechnical investigation of the site has been completed (LAW 1985). This investigation concluded that groundwater flow is generally towards the southeast at an estimated velocity of 2.5 m/y. This conclusion is based on groundwater and soil boring data and is very preliminary in nature. This analysis makes use of the data and conclusions developed during the preliminary geotechnical investigation to provide an upper-bound assessment of radioactive contamination from CEBAF operations. A site water balance was prepared to describe the behavior of the hydrologic environment that is in close agreement with the observed data. The transport of contamination in the groundwater regime is assessed using a one-dimensional model. The groundwater model includes the mechanisms of groundwater flow, groundwater recharge, radioactive decay, and groundwater activation. The model formulation results in a closed-form, exact, analytic solution of the concentration of contamination in the groundwater. The groundwater solution is used to provide a source term for a surface-water analysis. The surface-water and groundwater models are prepared for steady state conditions such that they represent conservative evaluations of CEBAF operations

  10. Propagation of an ultra intense laser pulse in an under dense plasma: production of quasi monoenergetic electron beams and development of applications

    International Nuclear Information System (INIS)

    This experimental study concerns the generation of electron beams with original properties. These electrons beams originate from the interaction of an ultra-intense and short laser pulse with a gas jet. Previously, these electron beams had a large divergence and a broad spectrum. A major improvement in this field was achieved when an electron beam with low divergence (10 mrad) and a peaked spectrum (170 MeV) was observed during this thesis, using a new single shot electron spectrometer. A parametric study of the interaction allowed to observe the evolution of the electron beam. Experiments have been carried out to deepen the characterization of the electron beam. The observation of transition radiation generated by the electrons at an interface shows that the electron beam interacts with the laser pulse during the acceleration. Radial oscillations of the electron beam around the laser axis, named betatron oscillations, were also observed on the electron spectra. Such a quasi-monoenergetic spectrum is essential for many applications. In order to justify the interest of this electron beam, several applications are presented: a sub-milli-metric gamma-ray radiography of dense objects, a dose profile of the electron beam comparable to present capabilities of photon sources for radiotherapy, a very short temporal profile useful for water radiolysis and the generation of a bright X-ray source with low divergence. (author)

  11. Removal of chloroform from biodegradable therapeutic microspheres by radiolysis.

    Science.gov (United States)

    Zielhuis, S W; Nijsen, J F W; Dorland, L; Krijger, G C; van Het Schip, A D; Hennink, W E

    2006-06-01

    Radioactive holmium-166 loaded poly(l-lactic acid) microspheres are promising systems for the treatment of liver malignancies. These microspheres are loaded with holmium acetylacetonate (HoAcAc) and prepared by a solvent evaporation method using chloroform. After preparation the microspheres (Ho-PLLA-MS) are activated by neutron irradiation in a nuclear reactor. It was observed that relatively large amounts of residual chloroform (1000-6000 ppm) remained in the microspheres before neutron irradiation. Since it is known that chloroform is susceptible for high-energy radiation, we investigated whether neutron and gamma irradiation could result in the removal of residual chloroform in HoAcAc-loaded and placebo PLLA-MS by radiolysis. To investigate this, microspheres with relatively high and low amounts of residual chloroform were subjected to irradiation. The effect of irradiation on the residual chloroform levels as well as other microsphere characteristics (morphology, size, crystallinity, molecular weight of PLLA and degradation products) were evaluated. No chloroform in the microspheres could be detected after neutron irradiation. This was also seen for gamma irradiation at a dose of 200 kGy phosgene, which can be formed as the result of radiolysis of chloroform, was not detected with gas chromatography-mass spectrometry (GC-MS). A precipitation titration showed that radiolysis of chloroform resulted in the formation of chloride. Gel permeation chromatography and differential scanning calorimetry showed a decrease in molecular weight of PLLA and crystallinity, respectively. However, no differences were observed between irradiated microsphere samples with high and low initial amounts of chloroform. In conclusion, this study demonstrates that neutron and gamma irradiation results in the removal of residual chloroform in PLLA-microspheres. PMID:16549282

  12. Development of a new picosecond pulse radiolysis system by using a femtosecond laser synchronized with a picosecond linac. A step to femtosecond pulse radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Yoichi; Yamamoto, Tamotsu; Miki, Miyako; Seki, Shu; Okuda, Shuichi; Honda, Yoshihide; Kimura, Norio; Tagawa, Seiichi [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Ushida, Kiminori

    1997-03-01

    A new picosecond pulse radiolysis system by using a Ti sapphire femtosecond laser synchronized with a 20 ps electron pulse from the 38 MeV L-band linac has been developed for the research of the ultra fast reactions in primary processes of radiation chemistry. The timing jitter in the synchronization of the laser pulse with the electron pulse is less than several picosecond. The technique can be used in the next femtosecond pulse radiolysis. (author)

  13. Programming for controlling of pulse radiolysis setup. Program RADIO96

    International Nuclear Information System (INIS)

    Program RADIO96 was written in Pascal using DELPHI 1.0 (Borland) programming platform. It can operate on IBM PC compatible computers in WINDOWS 3x or WINDOWS'95 environment. The program is dedicated to the pulse radiolysis setup based on the linear electron accelerator LAE 13/9 of the Department of Radiation Chemistry and Technology of the INCT. This work was based on apparatus and results described before and also on programming manuals of used equipment and technical data of programming platform. (author)

  14. Gamma radiolysis of EDTA in a simulated, mixed nuclear waste

    International Nuclear Information System (INIS)

    The effects of γ-irradiation on EDTA degradation have been studied. A simulant of Hanford's complex concentrate was prepared by adding EDTA to an inorganic matrix which was formulated based on past analyses of the actual Hanford complex concentrate waste. For the radiolysis study, aliquots of the simulated waste were then γ-irradiated. Each waste sample was analyzed to monitor the appearance of degradation products. Based on the results of this study, an assessment of the impact of EDTA degradation on the management of mixed wastes is offered. (author)

  15. Post-accident gas generation from radiolysis of organic materials

    International Nuclear Information System (INIS)

    This report presents a methodology for estimating the gas generation rates resulting from radiolysis of organic materials in paints and electrical cable insulation inside a nuclear reactor containment building under design basis accident conditions. The methodology was based on absorption of the radiation energies from the post-accident fission products and the assumed gas yields of the irradiated materials. A sample calculation was made using conservative assumptions, plant-specific data of a nuclear power plant, and a radiation source term which took into account the time-dependent release and physico-chemical behavior of the fission products

  16. Pulse radiolysis studies on superoxide reductase from Treponema pallidum.

    OpenAIRE

    Nivière, V; Lombard, M.; Fontecave, M.; Houée-Levin, C

    2001-01-01

    Superoxide reductases (SORs) are small metalloenzymes, which catalyze reduction of O2*- to H2O2. The reaction of the enzyme from Treponema pallidum with superoxide was studied by pulse radiolysis methods. The first step is an extremely fast bi-molecular reaction of the ferrous center with O2, with a rate constant of 6 x 10 (8) M(-1) s(-1). A first intermediate is formed which is converted to a second one with a slower rate constant of 4800 s(-1). This latter value is 10 times higher than the ...

  17. Radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety

    International Nuclear Information System (INIS)

    The pulse radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety (2'-bromo-2'-deoxyuridine 4, 3'-deoxy-3'-iodothymidine 5, 5'-deoxy-5'-iodouridine 6) has been studied. G(Hal) were determined by conductometry varying the experimental conditions (pH, saturation with Ar, N2O or air, addition of t-butanol). The results indicate that solvated electrons both add to the nucleobases and eliminate halogen ions from the halogenated sugar moiety. In the case of 4(and possibly of 5) the radical anion of the base transfers (k approximately 105s-1) an electron to the sugar-bound halogen atom thus cleaving the C-Hal bond. In competition with this reaction there is a protonation of the radical anion of the base by protons and by water. For the latter reaction constant of k = 5 x 103 M-1s-1 was estimated. Compound 4 has also been investigated by product analysis after 60-Co-γ-irradiation. In aerated solutions erythrose is formed with a G-value of 0.12. Its precursor radical is the 2'-radical generated from 4 by dissociative electron capture which reacts with O2 to the corresponding peroxyl radical. Erythrose is formed after a sequence of reactions, one of which involves the scission of the C-1'-C-2'bond. Under this condition G(HBr) as measured by pulse radiolysis is 0.8. Thus erythrose is formed in 15 per cent yield with respect to its precursor radical. This result is of importance in assessing the precursor radical of a similar product observed in irradiated DNA. (author)

  18. Wettability modification of human tooth surface by water and UV and electron-beam radiation

    Energy Technology Data Exchange (ETDEWEB)

    Tiznado-Orozco, Gaby E., E-mail: gab0409@gmail.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Unidad Académica de Odontología, Universidad Autónoma de Nayarit, Edificio E7, Ciudad de la Cultura “Amado Nervo”, C.P. 63190 Tepic, Nayarit (Mexico); Reyes-Gasga, José, E-mail: jreyes@fisica.unam.mx [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Instituto de Física, UNAM, Circuito de la Investigación s/n, Ciudad Universitaria, 04510 Coyoacan, México, D.F. (Mexico); Elefterie, Florina, E-mail: elefterie_florina@yahoo.com [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Beyens, Christophe, E-mail: christophe.beyens@ed.univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Maschke, Ulrich, E-mail: Ulrich.Maschke@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France); Brès, Etienne F., E-mail: etienne.bres@univ-lille1.fr [UMET, Bâtiment C6, Université de Lille 1, Sciences et Technologies, 59650 Villeneuve d' Ascq (France)

    2015-12-01

    The wettability of the human tooth enamel and dentin was analyzed by measuring the contact angles of a drop of distilled water deposited on the surface. The samples were cut along the transverse and longitudinal directions, and their surfaces were subjected to metallographic mirror-finish polishing. Some samples were also acid etched until their microstructure became exposed. Wettability measurements of the samples were done in dry and wet conditions and after ultraviolet (UV) and electron beam (EB) irradiations. The results indicate that water by itself was able to increase the hydrophobicity of these materials. The UV irradiation momentarily reduced the contact angle values, but they recovered after a short time. EB irradiation raised the contact angle and maintained it for a long time. Both enamel and dentin surfaces showed a wide range of contact angles, from approximately 10° (hydrophilic) to 90° (hydrophobic), although the contact angle showed more variability on enamel than on dentin surfaces. Whether the sample's surface had been polished or etched did not influence the contact angle value in wet conditions. - Highlights: • Human tooth surface wettability changes in dry/wet and UV/EB radiation conditions. • More variability in contact angle is observed on enamel than on dentin surfaces. • Water by itself increases the hydrophobicity of the human tooth surface. • UV irradiation reduces momentarily the human tooth surface hydrophobicity. • EB irradiation increases and maintains the hydrophobicity for a long time.

  19. Toxicity reduction for pharmaceuticals mixture in water by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Boiani, Nathalia Fonseca; Tominaga, Flavio Kiyoshi; Borrely, Sueli Ivone, E-mail: flavio_tominaga@hotmail.com, E-mail: sborrely@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2015-07-01

    The incorrect disposal of products is committing the environment quality once the aquatic environment is the main vehicle for dispersion of pollutants. Among the highlighted contaminants there are the pharmaceuticals, which are also released to the aquatic environment through the domestic sewage, hospitals and effluents. The monitoring of these pharmaceuticals in the environment has grown, showing many of them as persistent pollutants. Pharmaceuticals from different therapeutic classes have been detected in domestic sewage, surface water and groundwater around the world. Several studies evidenced Fluoxetine Hydrochloride residues in waters. Another important product is the Propranolol, used for heart disease treatments as far as fluoxetine is applied for treating mental diseases. The objective of this study was to apply the radiation processing for the abatement of pollutant in waters. Electron beam accelerator was used during irradiation of the mixture (Propranolol + Fluoxetine Hydrochloride) in aqueous solution. Acute toxicity assays were carried out for Vibrio fischeri marine bacterium, 15 minutes exposure. The results showed that irradiation (2.5kGy and 5.0kGy) enhanced the average effective concentration of the mixture, which means reduction of toxicity (56.34%, 55.70% respectively). Inverse effect was obtained with 7.5 kGy and 10 kGy. (author)

  20. Calculated depth-dose distributions for H+ and He+ beams in liquid water

    International Nuclear Information System (INIS)

    We have calculated the dose distribution delivered by proton and helium beams in liquid water as a function of the target-depth, for incident energies in the range 0.5-10 MeV/u. The motion of the projectiles through the stopping medium is simulated by a code that combines Monte Carlo and a finite differences algorithm to consider the electronic stopping power, evaluated in the dielectric framework, and the multiple nuclear scattering with the target nuclei. Changes in projectile charge-state are taken into account dynamically as it moves through the target. We use the MELF-GOS model to describe the energy loss function of liquid water, obtaining a value of 79.4 eV for its mean excitation energy. Our calculated stopping powers and depth-dose distributions are compared with those obtained using other methods to describe the energy loss function of liquid water, such as the extended Drude and the Penn models, as well as with the prediction of the SRIM code and the tables of ICRU.

  1. Calculated depth-dose distributions for H + and He + beams in liquid water

    Science.gov (United States)

    Garcia-Molina, Rafael; Abril, Isabel; Denton, Cristian D.; Heredia-Avalos, Santiago; Kyriakou, Ioanna; Emfietzoglou, Dimitris

    2009-08-01

    We have calculated the dose distribution delivered by proton and helium beams in liquid water as a function of the target-depth, for incident energies in the range 0.5-10 MeV/u. The motion of the projectiles through the stopping medium is simulated by a code that combines Monte Carlo and a finite differences algorithm to consider the electronic stopping power, evaluated in the dielectric framework, and the multiple nuclear scattering with the target nuclei. Changes in projectile charge-state are taken into account dynamically as it moves through the target. We use the MELF-GOS model to describe the energy loss function of liquid water, obtaining a value of 79.4 eV for its mean excitation energy. Our calculated stopping powers and depth-dose distributions are compared with those obtained using other methods to describe the energy loss function of liquid water, such as the extended Drude and the Penn models, as well as with the prediction of the SRIM code and the tables of ICRU.

  2. Toxicity reduction for pharmaceuticals mixture in water by electron beam irradiation

    International Nuclear Information System (INIS)

    The incorrect disposal of products is committing the environment quality once the aquatic environment is the main vehicle for dispersion of pollutants. Among the highlighted contaminants there are the pharmaceuticals, which are also released to the aquatic environment through the domestic sewage, hospitals and effluents. The monitoring of these pharmaceuticals in the environment has grown, showing many of them as persistent pollutants. Pharmaceuticals from different therapeutic classes have been detected in domestic sewage, surface water and groundwater around the world. Several studies evidenced Fluoxetine Hydrochloride residues in waters. Another important product is the Propranolol, used for heart disease treatments as far as fluoxetine is applied for treating mental diseases. The objective of this study was to apply the radiation processing for the abatement of pollutant in waters. Electron beam accelerator was used during irradiation of the mixture (Propranolol + Fluoxetine Hydrochloride) in aqueous solution. Acute toxicity assays were carried out for Vibrio fischeri marine bacterium, 15 minutes exposure. The results showed that irradiation (2.5kGy and 5.0kGy) enhanced the average effective concentration of the mixture, which means reduction of toxicity (56.34%, 55.70% respectively). Inverse effect was obtained with 7.5 kGy and 10 kGy. (author)

  3. Measuring the Gy:preventing convection in water calorimetry using a low duty cycle modulated beam

    International Nuclear Information System (INIS)

    The most fundamental method for determining the absorbed dose to water by radiation beams is by measuring the consequent temperature increase of the water. Water calorimeters used for this purpose are not irradiated uniformly; thus spatial dose gradients within the calorimeter give rise to significant heat transport effects that interfere with the measurement of the small temperature rise associated with radiotherapy doses (e.g. 240 μK/Gy at a typical dose rate of 1 Gy/min). When subjected to periodic exposure to radiation, the calorimeter response (registered as temperature at a point in the water) reaches steady-state oscillation in which effects due to heat conduction and convection may be studied as a function of modulation frequency, so that appropriate correction factors can be derived for desired operating conditions. Theoretical treatment of the behavior is greatly simplified if experimental conditions can be arranged so that convection is negligible. While this is usually done by refrigerating the calorimeter to 4 oC, where the thermal expansion coefficient of water is zero (thus, buoyancy forces due to density fluctuations effectively vanish), we present evidence suggesting that such conditions can be achieved at room temperature by reducing the duty cycle, or effective 'on' time of the radiation at a given shutter frequency. Results are presented here in the form of system transfer functions obtained under conditions of 50 and 3.5% duty cycle. Comparison of these measured transfer functions with the output of a three dimensional finite element model indicates that convection is greatly suppressed in the lower duty cycle case. Experimental uncertainty in these measurements is too large to conclude that convection is eliminated altogether, but more extended runs using this technique should enable a more definitive judgment as to whether the simpler conduction corrections alone can be applied.

  4. Sound field prediction of ultrasonic lithotripsy in water with spheroidal beam equations

    International Nuclear Information System (INIS)

    With converged shock wave, extracorporeal shock wave lithotripsy (ESWL) has become a preferable way to crush human calculi because of its advantages of efficiency and non-intrusion. Nonlinear spheroidal beam equations (SBE) are employed to illustrate the acoustic wave propagation for transducers with a wide aperture angle. To predict the acoustic field distribution precisely, boundary conditions are obtained for the SBE model of the monochromatic wave when the source is located on the focus of an ESWL transducer. Numerical results of the monochromatic wave propagation in water are analyzed and the influences of half-angle, fundamental frequency, and initial pressure are investigated. According to our results, with optimization of these factors, the pressure focal gain of ESWL can be enhanced and the effectiveness of treatment can be improved. (paper)

  5. Determination of AKR-2 leakage beam and verification at iron and water arrangements

    International Nuclear Information System (INIS)

    In this paper computational procedures and the experimental determination of the AKR-2 (Technical University Dresden) beam parameters are described. The calculations were performed using the MCNPX code () and the nuclear data libraries ENDF/B VI.2., ENDF/B VII.0., JEFF 3.1., JENDL 3.3 and BROND 3. The nuclear data were processed using the NJOY code (). The measurements were performed with a two-parameter stilbene spectrometer (). The measured leakage neutron spectrum was used as the input spectrum for the resulting neutron transport calculations. Because of the poor energy resolution of the experimental spectra the calculated photon leakage spectrum was used as the resulting input spectrum for the photon transport calculations. As the geometrically simple models acceptable for validation, transport through a 25 cm thick iron target and a 20 cm thick water target were used. Both targets were placed at the horizontal channel of the reactor AKR-2.

  6. Demonstration on endurance of ion exchange membrane immersed in high-concentration tritiated water under the Broader Approach Activities

    International Nuclear Information System (INIS)

    Highlights: • Endurance of Nafion ion exchange membrane immersed in 1.38 × 1012 Bq/kg of highly concentrated tritiated water was demonstrated. • Degradation of Nafion backbone structure by tritium beta was similar to that by gamma rays and electron beams at an equivalent dose. • Degradation directly by radiation was dominant at room temperature compared with that by reactions with radicals produced from water radiolysis. -- Abstract: The Nafion® ion exchange membrane is a key material for electrolysis cells of the water detritiation system. Endurance of Nafion ion exchange membrane immersed in 1.38 × 1012 Bq/kg of highly concentrated tritiated water has been demonstrated at room temperature for up to 2 years under the Broader Approach Activities. The curves of percent elongation at break vs. dose and tensile strength vs. dose for the Nafion membranes immersed in tritiated water were well consistent with those for Nafion membranes irradiated to an equivalent dose with gamma rays and electron beams. This shows that the degradation of Nafion backbone structure by tritium beta is similar to that by gamma rays and electron beams. The results of ferric Fenton test indicated that the degradation directly by radiation was dominant at room temperature compared with that by reactions with radicals produced from water radiolysis. The curve of ion exchange capacity vs. dose for the Nafion membranes immersed in tritiated water was also well consistent with that for Nafion membranes irradiated to an equivalent dose with gamma rays and electron beams. These results showed irradiation tests with gamma rays and electron beams were alternative for predicting degradation of ion exchange membrane by tritium beta

  7. Scattering of partially coherent electromagnetic beams by water droplets and ice crystals

    International Nuclear Information System (INIS)

    The conventional Lorenz–Mie theory is generalized for a case when the light source is partially spatially coherent. The influence of the degree of coherence of the incident field on the generalized Mueller matrix and the spectral degree of coherence of the scattered light is analytically studied by using the vector field instead of the scalar field to extend previous results on the angular intensity distribution. The results are compared with the Mueller matrix obtained from the Discrete Dipole Approximation (DDA) method, which is an average over an ensemble of stochastic incident beams. Special attention is paid to the Mueller matrix elements in the backward direction, and the results show some Mueller matrix elements, such as P22, depend monotonically on the coherence length of the incident beam. Therefore, detecting back scattering Mueller matrix elements may be a promising method to measure the degree of coherence. The new formalism is applied to cases of large spherical droplets in water clouds and hexagonal ice crystals in cirrus clouds. The corona and glory phenomena due to spheres and halos associated with hexagonal ice crystals are found to disappear if the incident light tends to be highly incoherent. -- Highlights: • The Lorenz–Mie theory is generalized for a case when the light source is partially coherent. • The generalized Mueller matrix is studied analytically using vector incident field. • Analytical results are validated by DDA simulation. • The formalism is applied to cases of water droplets and ice crystals in clouds. • We found backscattering is sensitive to the coherence length of the incident light

  8. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja; Getoff, Nikola;

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5−6.2)×109 dm3 mol−1 s−1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320−340 nm. Their decay wa...... to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out....

  9. Radiolysis Model Formulation for Integration with the Mixed Potential Model

    Energy Technology Data Exchange (ETDEWEB)

    Buck, Edgar C.; Wittman, Richard S.

    2014-07-10

    The U.S. Department of Energy Office of Nuclear Energy (DOE-NE), Office of Fuel Cycle Technology has established the Used Fuel Disposition Campaign (UFDC) to conduct the research and development activities related to storage, transportation, and disposal of used nuclear fuel (UNF) and high-level radioactive waste. Within the UFDC, the components for a general system model of the degradation and subsequent transport of UNF is being developed to analyze the performance of disposal options [Sassani et al., 2012]. Two model components of the near-field part of the problem are the ANL Mixed Potential Model and the PNNL Radiolysis Model. This report is in response to the desire to integrate the two models as outlined in [Buck, E.C, J.L. Jerden, W.L. Ebert, R.S. Wittman, (2013) “Coupling the Mixed Potential and Radiolysis Models for Used Fuel Degradation,” FCRD-UFD-2013-000290, M3FT-PN0806058

  10. The sonolysis and radiolysis of adenine and related biomolecules

    International Nuclear Information System (INIS)

    The sonolysis of adenine, its nucleoside adenosine and the carbohydrates glucose, fructose and ribose were investigated at 459 Hz. The insonation of air-saturated aqueous adenine solutions degrades adenine at a rate that is linear with time and independent of the initial concentration. The radiolytic decomposition of air-saturated aqueous adenine solutions were also investigated and the degradation products found to be essentially identical to those obtained by sonolysis. since the products derived from sonolysis and radiolysis were similar, a degradation mechanism can be proposed that accounts for all the observed products. The major feature of this mechanism is that the principal loci of attack are the C(8) position and the central C(4)-C(5) double bond. The sonolysis of air-saturated aqueous solutions of the carbohydrates results in the formation of products analogous to those produced by ionizing radiation. While two types of products are formed in the radiolysis of carbohydrate solutions, depending on the initial presence or absence of oxygen, the sonolysis of air-saturated carbohydrate solutions leads to the formation of both types of products. This is due to the depletion of oxygen from the solution during insonation. Existing mechanisms for the radiolytic decomposition of carbohydrates in the presence and absence of oxygen can be modified to rationalize the sonolysis products. Insonation of an aqueous solution of adenosine resulted in the production of adenine and ribose. The other products are consistent with those obtained in the ultrasonic degradation of adenine and ribose

  11. Pulse and steady-state radiolysis of sodium tetraphenylborate solutions

    International Nuclear Information System (INIS)

    Major products and their G-Values from Co-60 gamma radiolysis of 0.05 M sodium tetraphenylborate (NaTPB) at 25 degrees C are hydrogen (0.46), biphenyl (2.0), benzene (1.3), and phenol (0.41). A dose of 4.4 Mrad increased the pH from 8.2 (initial) to 9.2. Reactions of transient species in aqueous TPB- solutions were studied by electron pulse radiolysis. The lack of reactivity between TPB- and eaq- was shown by monitoring was shown by monitoring the transient optical absorbance of eaq-. The results suggests that OH+ addition is the main reaction pathway. Using N2O saturation, the authors found k = 6.2x109 M-1s-1. A mechanism based on an initial 1st order decomposition of the OH+ adduct, (C6H5)3BC6H5OH-., with a measured rate constant of 4x104 s-1 is proposed. Kinetic modeling based on the proposed mechanistic scheme gives good agreement with experimental results

  12. Pulse radiolysis of aqueous solutions of sodium tetraphenylborate

    International Nuclear Information System (INIS)

    In previous work on the 60Co γ-radiolysis of aqueous tetraphenylborate (TPB-) solutions carried out in this laboratory, it was found that several organic products, including benzene, phenol and biphenyl, are produced with substantial yield. However, the reaction mechanism was not established. In the present study, reactions initiated by OH· radicals, N3· radicals and e-aq in aqueous TPB- solutions were studied by pulse radiolysis using a 600 keV Febetron electron accelerator. The lack of reactivity between TPB- and e-aq was demonstrated by directly monitoring the transient optical absorbance of e-aq. Concerning the reaction with OH·, two schemes were considered: (1) electron transfer from B(C6H5)4- to OH·; or (2) OH· addition to B(C6H5)4-. Comparison of observed transient absorption spectra with expectations based on the two different schemes suggests that OH· addition is the dominant reaction pathway under conditions of N2O saturation, with an experimentally determined second-order rate constant of 6.2 x 109 M-1 s-1. A mechanism based on an initial first-order self-decomposition of the OH· adduct, (C6H5)3BC6H5OH·-, with measured rate constant of 4 x 104s-1 is proposed. Kinetic modeling on the proposed mechanistic scheme gives good agreement with our experimental results. (author)

  13. Radiolysis of acrinol on radio-sterilization for acrinol pharmaceutical

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Syojiro; Nishimura, Reiko; Kanbashi, Toshitaka; Jo, Hisanobu; Koide, Hiroaki

    1983-11-01

    Acrinol in dry solid state after gamma irradiation with 80 kGy (8 Mrad) undergoes 8% decomposition, with G(-M)=30, and in wet solid state (10% moisture content) undergoes 15% decomposition, with G(-M)=56, as shown by absorbed spectrometric measurement. From these results, it is estimated that the irradiation dose of 25 kGy (2.5 Mrad) preferred by many countries as a sterilization dose will achieve the radiolysis rate of 2.8% or 4.7% for dry solid state or wet solid state acrinol, respectively. The stickiness of plaster tape made of raw rubber and polyterpene resin does not decrease with an irradiation dose of less than 40 kGy (4 Mrad). There a radio-sterilization dose of 25 kGy (2.5 Mrad) may be applied to solid pharmaceuticals such as commercial rubber adhesive plaster with acrinol pad. Acrinol in 0.1% aqueous solution after irradiation of 10 kGy (1 Mrad) at room temperature undergoes 20% decomposition, with G(-M)=0.5. The radiolysis rate in this state is estimated to be 45% with a dose of 25 kGy (2.5 Mrad). There radio-sterilization with this dose must not be applied to liquid pharmaceuticals such as 0.1% acrinol aqueous solution. It has been reported by Hosobuchi and Sato that the antimicrobial effect of irradiated acrinol to Staphlococcus aureus increased with irradiation dose.

  14. Salt effect in radiolysis of frozen cyanocobalamine solutions

    International Nuclear Information System (INIS)

    Investigated has been radiolysis of aqueous solutions of cyanocobalamine (vitamin B-12) with 200 mg/l concentration, containing and not containing sodium chloride in the concentration of 0.9 weight % NaCl. The irradiation has been carried our using γ-installation (with the dose capacity 5 Mrad/hr) in sealed in the air glass ampoules at 18, 0, -11, -22, -50, -78 and 196 deg C. It has been shown that in the course of liquid phase radiolysis NaCl presence in the solution does not practicaly affect the degree of radiational decomposition of cyanocobalamine. At the temperature decrease strong effect of salt is detected in non-salt solution practically complete stabilization of cyanocobalamine is observed already at -11 deg C, whereas in the presence of salt close grade of protection is reached only at -78 deg C and does not change at the temperature decrease down to -196 deg C. The effect of cryostabilization can be accounted for by two reasons: the solution microstra-tification at freezing, so that in every separate phase there is mainly one of the system components and diffusion rate reduction of hydroxile radicals at temperature decrease

  15. Pulse radiolysis experiments: synthesis and analysis of composite spectra

    International Nuclear Information System (INIS)

    Methods are outlined for compiling optical spectra obtained in pulse radiolysis experiments in a form suitable for detailed synthesis and analysis of composite spectra. The experimental data are processed with a programmable calculator having a cassette recorder for the storage of the output data files and a peripheral plotter. The spectra are first smoothed by fitting them parabolically segment by segment. The overall spectrum is then assembled in digital form by interpolating the fitted data on a 1 nm grid and the results are stored on cassette files for further processing. Composite spectra can be readily calculated and plotted from the data on these files or known components can be subtracted from observed spectra to examine underlying contributions. The use of the fairly simple data processing methods described here permits an interactive mode of operation by the investigator which can maximize insight into details of the various contributions to an observed spectrum. Several examples of the use of these methods in conjunction with data obtained with a computer controlled pulse radiolysis data acquisition system are given. (author)

  16. Is solvent radiolysis a safety problem for PUREX plant performance?

    International Nuclear Information System (INIS)

    During two campaigns with shortly cooled low burn-up and with high burn-up fuel of 2 to 4 years cooling time, respectively, the solvent quality of the first solvent cycle of the WAK plant has been analyzed. Quick analytical methods were used to obtain information on the concentration of radiolysis products. Applying formation rates from a solvent radiolysis model, the total radiation absorbed dose of the solvent was estimated and could be broken down in to the α- and β/γ-contributions. These figures compare well with those obtained if one considers the irradiation history of WAK plant solvent. The α-irradiation of extracted plutonium contributes the major part of radiation damage to the solvent. However, only one half of the observed α-dose is due to the stay of plutonium loaded solvent in the extraction banks. The other half is caused by α-irradiation of organic slip phase, which is collected in aqueous plutonium product catch tanks and is discontinuously fed back to the solvent cycle. (orig./RB)

  17. Influence of persulfate ions on the removal of phenol in aqueous solution using electron beam irradiation

    International Nuclear Information System (INIS)

    The removal of phenol (Co = 100 μM) during electron beam irradiation was studied in pure water and in the presence of HCO3- and Br- ions. It was found that the introduction of S2O82- ions (1 mM), by generating SO4-· radicals increases the radiation yield of phenol removal. 90% removal of phenol was obtained with radiation doses 600 and 1200 Gy with and without S2O82- ions respectively. This system induced smaller oxygen consumption with smaller concentration of catechol and hydroquinone found in the solution. HCO3- and Br- have an inhibiting effect in the presence as in the absence of S2O82-. In most cases, the introduction of S2O82- ions in water radiolysis system can advantageously increase the yield of organic compounds removal by oxidation.

  18. Radiolytic corrosion of uranium dioxide induced by He2+ localized irradiation of water: Role of the produced H2O2 distance

    Science.gov (United States)

    Traboulsi, Ali; Vandenborre, Johan; Blain, Guillaume; Humbert, Bernard; Haddad, Ferid; Fattahi, Massoud

    2015-12-01

    The short-range (few μm in water) of the α-emitting from the spent fuel involves that the radiolytic corrosion of this kind of sample occurs at the solid/solution interface. In order to establish the role of localization of H2O2 species produced by the He2+ particle beam in water from the surface, we perform UO2 radiolytic corrosion experiment with different distance between H2O2 production area and UO2 surface. Then, in this work, the radiolytic corrosion of UO2 particles by oxidative species produced by 4He2+ radiolysis of water was investigated in open to air atmosphere. The dose rate, the localization of H2O2 produced by water radiolysis and the grain boundaries present on the surface of the particles were investigated. UO2 corrosion was investigated by in situ (during irradiation) characterization of the solid surface, analysis of H2O2 produced by water radiolysis and quantification of the uranium species released into the solution during irradiation. Characterization of the UO2 particles, surface and volume, was realized by Raman spectroscopy. UV-vis spectrophotometry was used to monitor H2O2 produced by water radiolysis and in parallel the soluble uranium species released into the solution were quantified by inductively coupled plasma mass spectrometry. During the He2+ irradiation of ultra-pure water in contact with the UO2 particles, metastudtite phase was formed on the solid surface indicating an oxidation process of the particles by the oxidative species produced by water radiolysis. This oxidation occurred essentially on the grain boundaries and was accompanied by migration of soluble uranium species (U(VI)) into the irradiated solution. Closer to the surface the localization of H2O2 formation, higher the UO2 oxidation process occurs, whereas the dose rate had no effect on it. Simultaneously, closer to the surface the localization of H2O2 formation lower the H2O2 concentration measured in solution. Moreover, the metastudtite was the only secondary

  19. Spectrometric study of X-ray beams transmitted and scattered by little phantoms of water, oily substance and bone

    International Nuclear Information System (INIS)

    This is a study of typical diagnostic X ray beams between 60 and 100 kVp. On a first hand, we consider the X ray beams transmitted by a little phantom (cylinder of 3 cm of diameter and high of 3 cm) of water, oily substance (olive oil) and bone (bone equivalent material). Water and oily substance present a transmitted X ray beam slightly equivalent either in quality or in quantity. Both are different of the transmitted beam by bone. On the other hand, the scattered radiations by those phantoms are studied over the energy range (60 to 100 kVp) and the scattering angle theta between the detector Na I (Tl) and the incident beam axis. The probability Q of a primary photon to be scattered by a medium (water, oil or bone) reported to one photon tranmitted by the same medium has been calculated for each medium. The results show a similitude with the angular distribution of the probability K(theta) of a primary photon to be scattered calculated by the Klein-Nishina formula

  20. Spatial fragment distribution from a therapeutic pencil-like carbon beam in water

    International Nuclear Information System (INIS)

    The latest heavy ion therapy tends to require information about the spatial distribution of the quality of radiation in a patient's body in order to make the best use of any potential advantage of swift heavy ions for the therapeutic treatment of a tumour. The deflection of incident particles is described well by Moliere's multiple-scattering theory of primary particles; however, the deflection of projectile fragments is not yet thoroughly understood. This paper reports on our investigation of the spatial distribution of fragments produced from a therapeutic carbon beam through nuclear reactions in thick water. A ΔE-E counter telescope system, composed of a plastic scintillator, a gas-flow proportional counter and a BGO scintillator, was rotated around a water target in order to measure the spatial distribution of the radiation quality. The results revealed that the observed deflection of fragment particles exceeded the multiple scattering effect estimated by Moliere's theory. However, the difference can be sufficiently accounted for by considering one term involved in the multiple-scattering formula; this term corresponds to a lateral 'kick' at the point of production of the fragment. This kick is successfully explained as a transfer of the intra-nucleus Fermi momentum of a projectile to the fragment; the extent of the kick obeys the expectation derived from the Goldhaber model

  1. Design concept for a direct water-cooled silicon crystal for use in a high-power synchrotron radiation beam

    International Nuclear Information System (INIS)

    The onset of high-power Synchrotron Radiation beams, now available at several of the Synchrotron Radiation facilities, has resulted in a search for new ways on how to handle the increased thermal load on optical components that are directly exposed to these beams. This report examines one possible way of the direct water-cooling of a silicon crystal as used in monochromators and how to get the water to the crystal with the least possible strain on the crystal. Suggestions are made on how to mount the crystal assembly in an experimental setup, so that physical properties of the crystal can be measured during direct exposure to a suitable high-power Synchrotron Radiation beam. Ways of making small correction movements to the crystal in two directions are outlined. (author)

  2. Thermo-acoustic Sound Generation in the Interaction of Pulsed Proton and Laser Beams with a Water Target

    CERN Document Server

    Lahmann, R; Graf, K; Hößl, J; Kappes, A; Katz, U; Mecke, K; Schwemmer, S

    2015-01-01

    The generation of hydrodynamic radiation in interactions of pulsed proton and laser beams with matter is explored. The beams were directed into a water target and the resulting acoustic signals were recorded with pressure sensitive sensors. Measurements were performed with varying pulse energies, sensor positions, beam diameters and temperatures. The obtained data are matched by simulation results based on the thermo-acoustic model with uncertainties at a level of 10%. The results imply that the primary mechanism for sound generation by the energy deposition of particles propagating in water is the local heating of the medium. The heating results in a fast expansion or contraction and a pressure pulse of bipolar shape is emitted into the surrounding medium. An interesting, widely discussed application of this effect could be the detection of ultra-high energetic cosmic neutrinos in future large-scale acoustic neutrino detectors. For this application a validation of the sound generation mechanism to high accur...

  3. Estimation of turbulent parameters based on the intensity scintillations of the laser beam propagated through a turbulent water layer

    Science.gov (United States)

    Kulikov, Victor A.

    2016-03-01

    The inner scale and the refractive-index structure parameter Cn2 are estimated by the intensity scintillations of the laser beam propagated through the turbulent water layer. The laser beam scintillations caused by underwater propagation can be described in the framework of a turbulence model with accounting of the inner scale. An intensity field has been observed at a 2 m distance when the laser beam passed through a water convective cell with a characteristic Rayleigh number of about 108. Similar intensity fields were simulated by using the split-step method. Characteristics of the experimentally obtained and numerically simulated intensity fields are compared and analyzed. A simple method of the turbulent parameter estimation is proposed.

  4. Monte Carlo Calculations of Dose to Medium and Dose to Water for Carbon Ion Beams in Various Media

    DEFF Research Database (Denmark)

    Herrmann, Rochus; Petersen, Jørgen B.B.; Jäkel, Oliver;

    materials exposed to carbon ion beams. The scored track-length fluence spectrum Φi for a given particle i at the energy E, is multiplied with the mass stopping power for target material for calculating Dm . Similarly, Dw is calculated by multiplying the same fluence spectrum with the mass stopping power...... the PSTAR, ASTAR stopping power routines available at NIST1 and MSTAR2 provided by H. Paul et al. 3     Results For a pristine carbon ion beam we encountered a maximum deviation between Dw and Dm up to 8% for bone. In addition we investigate spread out Bragg peak configurations which dilutes the effect......1     Background In clinical practice the quantity dose to water (Dw ) is used as a reference standard for dosimeters and treatment planning systems. Treatment planning systems usually rely on analytical representation of the particle beam, which are normally expressed as dose with respect to water...

  5. Full scale electron beam systems for treatment of water, wastewater and medical waste

    International Nuclear Information System (INIS)

    High energy electron accelerators have been used in numerous applications for several decades. In the early 1980's several attempts to use electron accelerators for the disinfection of sludge proved that the technology could be used for that application. One such facility was designed, built and tested for one year at the Miami-Dade Virginia Key Wastewater Treatment Plant. The process successfully disinfected anaerobically digested sludge. However, due to changing local regulations the process was never implemented. Now this process may provide a viable alternative for the ultimate destruction of toxic and hazardous organic chemicals from water and sludges. When high energy electrons impact an aqueous solution, with or without particulate matter present, reactive transient species are formed. The three transient species of most interest are the aqueous electron, e-aq, hydrogen radical, H·, and the hydroxyl radical, ·OH. The relative concentration of these radicals in an irradiated solution of pure water is 44, 10 and 46%, respectively. The absolute concentration of the radicals is dose and water quality dependent, but is in excess of mM levels in potable, raw and secondary wastewater effluent at our facility. This paper describes the facilities at the Electron Beam Research Facility (EBRF) in Miami, FL. The accelerator is a 1.5 MeV, 50 mA insulated core transformer type. Several areas of research have been the focus of the studies with an interdisciplinary team of faculty and students in engineering and science. The areas included are, inactivation of bacteria in raw and chlorinated and unchlorinated secondary wastewater and the changes in biochemical oxygen demand and chemical oxygen demand in the raw and unchlorinated secondary wastewater. The removal of toxic chemicals has also been studied in some detail. These studies have been conducted both at the EBRF and using 60Co gamma irradiation. To examine the effect of water quality on the destruction of the

  6. Basin Economic Allocation Model (BEAM): An economic model of water use developed for the Aral Sea Basin

    Science.gov (United States)

    Riegels, Niels; Kromann, Mikkel; Karup Pedersen, Jesper; Lindgaard-Jørgensen, Palle; Sokolov, Vadim; Sorokin, Anatoly

    2013-04-01

    The water resources of the Aral Sea basin are under increasing pressure, particularly from the conflict over whether hydropower or irrigation water use should take priority. The purpose of the BEAM model is to explore the impact of changes to water allocation and investments in water management infrastructure on the overall welfare of the Aral Sea basin. The BEAM model estimates welfare changes associated with changes to how water is allocated between the five countries in the basin (Kazakhstan, Kyrgyz Republic, Tajikistan, Turkmenistan and Uzbekistan; water use in Afghanistan is assumed to be fixed). Water is allocated according to economic optimization criteria; in other words, the BEAM model allocates water across time and space so that the economic welfare associated with water use is maximized. The model is programmed in GAMS. The model addresses the Aral Sea Basin as a whole - that is, the rivers Syr Darya, Amu Darya, Kashkadarya, and Zarafshan, as well as the Aral Sea. The model representation includes water resources, including 14 river sections, 6 terminal lakes, 28 reservoirs and 19 catchment runoff nodes, as well as land resources (i.e., irrigated croplands). The model covers 5 sectors: agriculture (crops: wheat, cotton, alfalfa, rice, fruit, vegetables and others), hydropower, nature, households and industry. The focus of the model is on welfare impacts associated with changes to water use in the agriculture and hydropower sectors. The model aims at addressing the following issues of relevance for economic management of water resources: • Physical efficiency (estimating how investments in irrigation efficiency affect economic welfare). • Economic efficiency (estimating how changes in how water is allocated affect welfare). • Equity (who will gain from changes in allocation of water from one sector to another and who will lose?). Stakeholders in the region have been involved in the development of the model, and about 10 national experts, including

  7. Perturbation correction factors for the NACP-02 plane-parallel ionization chamber in water in high-energy electron beams

    International Nuclear Information System (INIS)

    Recent dosimetry protocols for clinical high-energy electron beams recommend measurements of absorbed dose-to-water with a plane-parallel or cylindrical ionization chamber. For well-guarded plane-parallel ionization chambers, the ionization chamber perturbation factor in water, pQ, has a recommended value of unity in all protocols. This assumption was investigated in detail in this study for one of the recommended ionization chambers in the protocols: the Scanditronix NACP-02 plane-parallel ionization chamber. Monte Carlo (MC) simulations of the NACP-02 ionization chamber with the EGSnrc code were validated against backscatter experiments. MC simulations were then used to calculate pwall, pcav and pQ perturbation factors and water-to-air Spencer-Attix stopping powers in 4-19 MeV electron beams of a calibration laboratory (NPL), and in 6-22 MeV clinical electron beams from a Varian CL2300 accelerator. Differences between calculated and the currently recommended (Burns et al 1996 Med. Phys. 23 383-8) stopping powers, water-to-air, were found to be limited to 0.9% at depths between the reference depth zref and the depth where the dose has decreased to 50% of the maximum dose, R50. pwall was found to exceed unity by 2.3% in the 4 MeV NPL calibration beam at zref. For higher energy electron beams pwall decreased to a value of about 1%. Combined with a pcav about 1% below unity for all energies at zref, this was found to cause pQ to exceed unity significantly for all energies. In clinical electron beams all three perturbation factors were found to increase with depth. Our findings indicate that the perturbation factors have to be taken into account in calibration procedures and for clinical depth dose measurements with the NACP-02 ionization chamber

  8. Radiation stability of selected ionic liquids: a pulse radiolysis study

    International Nuclear Information System (INIS)

    One important potential application of ionic liquids (IL) is as a medium for processing of spent nuclear fuel. It is therefore imperative to study the radiation chemistry of ILs, not only to determine their radiolytic products and degradation pathways, but also to describe how the radiolysis may affect or interfere in the separation processes. An understanding of Radiation Chemistry of ILs would also facilitate general chemical reactivity in this medium, which will aid in the development of energy production, chemical industry and environmental applications. We were interested in understanding how the specific physical properties of ionic liquids influence the dynamical processes that determine the stability and lifetimes of reactive intermediates and thereby affect the courses of chemical reactions and product distributions in this medium. In the pulse radiolysis experiments on Imidazolium based ILs (1-Ethyl-3-methylimidazolium) (Ethyl sulphate) or (Emim) (EtSO4) under oxidizing or reducing conditions, we observed a transient peak at 320 nm. This absorption may be due to the formation of a radical as electron reacts with the imidazolium cation of the ionic liquid. We have not observed hydrated electrons because the electron reacts with imidazolium cation very fast. Pulse radiolysis experiments have also been performed on FAP (Fluoro Alkyl Phosphates) ILs having imidazolium as cation e.g. (1-Ethyl-3-methylimidazolium) (tris(pentafluoroethyl) trifluorophosphate) or FAP-1 and (1-(2-HydroxyEthyl-3-methylimidazolium) (tris(pentafluoroethyl) trifluorophosphate) or FAP-2. FAP-ionic liquids show an excellent hydrolytic stability, low viscosity and high electrochemical and thermal stability that makes them attractive for use in electrochemical devices and as a new media for application in modern technologies and chemical synthesis. The time-resolved transient spectra of FAP ILs were recorded and characterized under different experimental conditions. The formation and decay

  9. Effect of alpha-radiolysis on the dissolution of UO2 doped with alpha emitters under anoxic conditions

    International Nuclear Information System (INIS)

    The α emissions constitute almost entirely the radiation field of spent nuclear fuel after 500 years in a geological repository. In this work the effect of α-radiolysis on the fuel dissolution in the near field was studied. Pellets of UO2 doped with 10% wt. and 0.1% wt. of ''238 Pu (α-emitter) were prepared using a solgel method which provides homogenous distribution of the dopant in the UO2 matrix. The sintered materials were extensively characterized. Static leaching tests on these materials were carried out under anoxic conditions in deaerated water at room temperature. The results show that the uranium release from the matrix increase for the higher dopant concentration. Under the experimental conditions used it was difficult to observe a clear radiolysis effect on dissolution of the material containing 0.1% wt. of ''238 Pu. In order to study the radiation damage due to α decay in the fluorite type lattice of the UO2, the variation of the lattice parameter as a function of time was measured. An increase of the lattice parameter of approx 0,2% was observed after 1,5 months of storage in the UO2 doped with 10% wt. of plutonium. In the case of the UO2 doped with 0,1% wt. ''238 Pu, the lattice parameter did not vary significantly during the same time interval. The possible effects of damage accumulation on UO2 dissolution are discussed. (Author) 7 refs

  10. Radiolysis of HA in aqueous solutions using gamma rays

    International Nuclear Information System (INIS)

    The present work investigated the radiolysis of HA (Humic acids) in aqueous solutions and under gamma radiation. Absorbances at the range of 200-800 nm and chemical oxygen demand (COD) were used to characterize the degree of degradation of HA, The results indicated that absorbances and the concentrations of COD were decreased with increasing of irradiation dose while with increasing of irradiation dose the pH of the solutions was decreased at first and then increase. In addition, the effects of initial pH and primary solution concentrations on HA degradation were also investigated. It is shown that the higher primary solution concentrations, the lower degradation efficiency under the same irradiation dose. And the degradation efficiency of HA under neutral conditions is better than in acidic or alkaline conditions. (authors)

  11. Study of proton radiolysis of solid uracil film

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    In order to understand the molecules mechanism of ion irradiation,which has been widelyused in many fields such as cancer therapy, uracil, one of the bases ofnucleic acid,waschosen in the low energy ion radiolysis research. The solid uracil films with mass thickness of0.314 mg/cm2 were irradiated by 200 keV H+ ions.The experimental results show that 200 keVH+ ions are effective in decomposition of uracil molecules. One of the decomposition products,5,6-dihydro-uracil, was separated by high performance liquid chromatograph (HPLC) anddetected using an UV-light detector. Its yield increases first but then decreases as the ion doseincreasing. In addition, the mechanism of uracil decomposition and 5,6-dihydro-uracilformation was also discussed.

  12. Pulse radiolysis of tetraalkylammonium hydroxides in alkaline solution containing oxygen

    International Nuclear Information System (INIS)

    In the pulse radiolysis of aqueous oxygenated solutions of tetraalkylammonium hydroxides there is a build-up of ozonide ion lasting up to 100 μs after the pulse. The build-up does not occur in solutions containing a twenty fold (reactivity) excess of N2O to O2. The influence of various concentrations of tetraalkylammonium cations, oxygen and different reactivity ratios of N2O to O2 on the build-up of ozonide ion after the pulse was investigated. The reaction rates of O2-and O- with peroxy radicals and organic cations, respectively, control the nature of the observed build-up and decay of ozonide ion. (author)

  13. Radiolysis of alanine adsorbed in a clay mineral

    International Nuclear Information System (INIS)

    Optical activity in molecules is a chemical characteristic of living beings. In this work, we examine the hypothesis of the influence of different mineral surfaces on the development of a specific chirality in organic molecules when subjected to conditions simulating the primitive Earth during the period of chemical evolution. By using X-ray diffraction techniques and HPLC/ELSD to analyze aqueous suspensions of amino acids adsorbed on minerals irradiated in different doses with a cobalt-60 gamma source, the experiments attempt to prove the hypothesis that some solid surfaces (like clays and meteorite rocks) may have a concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) for some organic compounds (like some amino acids) adsorbed on them. Preliminary results show a slight difference in the adsorption and radiolysis of the D-and L-alanine

  14. Computerised pulse-radiolysis system for gas-phase kinetics

    International Nuclear Information System (INIS)

    Pulse-radiolysis equipment for studies of radical reaction kinetics in the gas phase is described. The equipment is built around an accelerator of the Febetron type for 800 keV electrons. The analysing light is pulsed with optical feedback regulation of the intensity to increase the luminosity ca. 50 times during the measurement. It is equipped with photoelectric detection of transient optical absorptions in the time interval 1 x 10-8 10-3 s of radicals in the wavelength range 200-900 mm. The stray-light level is low (3 radical in SF6 bath gas are in the interval ± 10% of the literature value. The equipment is intended for measurements of reaction kinetics related to combustion and atmospheric chemistry. (au) (13 refs.)

  15. Pulse radiolysis studies on superoxide reductase from Treponema pallidum

    CERN Document Server

    Nivière, V; Fontecave, M; Houée-Levin, C

    2015-01-01

    Superoxide reductases (SORs) are small metalloenzymes, which catalyze reduction of O2*- to H2O2. The reaction of the enzyme from Treponema pallidum with superoxide was studied by pulse radiolysis methods. The first step is an extremely fast bi-molecular reaction of the ferrous center with O2, with a rate constant of 6 x 10 (8) M(-1) s(-1). A first intermediate is formed which is converted to a second one with a slower rate constant of 4800 s(-1). This latter value is 10 times higher than the corresponding one previously reported in the case of SOR from Desulfoarculus baarsii. The reconstituted spectra for the two intermediates are consistent with formation of transient iron-peroxide species.

  16. Quality indexes based on water measurements for low and medium energy x-ray beams: A theoretical study with PENELOPE

    Energy Technology Data Exchange (ETDEWEB)

    Chica, U. [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada, Spain and FISRAD S.A.S Carrera 64 a No 22-41, Bogotá D.C. (Colombia); Anguiano, M.; Lallena, A. M., E-mail: lallena@ugr.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain); Vilches, M. [Servicio de Radiofísica, Hospital Universitario “San Cecilio”, Avda. Dr. Olóriz, 16, E-18012 Granada (Spain)

    2014-01-15

    Purpose : To study the use of quality indexes based on ratios of absorbed doses in water at two different depths to characterize x-ray beams of low and medium energies. Methods : A total of 55 x-ray beam spectra were generated with the codes XCOMP5R and SPEKCALC and used as input of a series of Monte Carlo simulations performed with PENELOPE, in which the percentage depth doses in water and thek{sub Q,Q{sub 0}} factors, defined in the TRS-398 protocol, were determined for each beam. Some of these calculations were performed by simulating the ionization chamber PTW 30010. Results : The authors found that the relation betweenk{sub Q,Q{sub 0}} and the ratios of absorbed doses at two depths is almost linear. A set of ratios statistically compatible with that showing the best fit has been determined. Conclusions : The results of this study point out which of these ratios of absorbed doses in water could be used to better characterize x-ray beams of low and medium energies.

  17. Low-Energy (Methanol Radiolysis of Astrochemical Interest

    Science.gov (United States)

    Sullivan, Kristal K.; Boamah, Mavis D.; Shulenberger, Katie E.; Chapman, Sitara; Atkinson, Karen E.; Boyer, Michael C.; Arumainayagam, Christopher R.

    2016-03-01

    We report the first infrared study of the low-energy (methanol. Our goal is to simulate processes which occur when high-energy cosmic rays interact with interstellar and cometary ices, where methanol, a precursor of several prebiotic species, is relatively abundant. The interactions of high-energy radiation, such as cosmic rays (Emax ˜1020 eV), with matter produce large numbers of low-energy secondary electrons, which are known to initiate radiolysis reactions in the condensed phase. Using temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS), we have investigated low-energy (5-20 eV) and high-energy (˜1000 eV) electron-induced reactions in condensed methanol (CH3OH). IRAS has the benefit that it does not require thermal processing prior to product detection. Using IRAS, we have found evidence for the formation of ethylene glycol (HOCH2CH2OH), formaldehyde (CH2O), dimethyl ether (CH3OCH3), methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and the hydroxyl methyl radical (•CH2OH) upon both low-energy and high-energy electron irradiation of condensed methanol at ˜85 K. Additionally, TPD results, presented herein, are similar for methanol films irradiated with both 1000 eV and 20 eV electrons. These IRAS and TPD findings are qualitatively consistent with the hypothesis that high-energy condensed phase radiolysis is mediated by low-energy electron-induced reactions. Moreover, methoxymethanol (CH3OCH2OH) could serve as a tracer molecule for electron-induced reactions in the interstellar medium. The results of experiments such as ours may provide a fundamental understanding of how complex organic molecules (COM) are synthesized in cosmic ices.

  18. Pulse Radiolysis of Aqueous Solutions of Aniline and Substituted Anilines

    International Nuclear Information System (INIS)

    The primary reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals with aniline and the aniline cation in aqueous solutions have been studied by the technique of pulse radiolysis and by determination of end products after y-radiolysis. Hydrogen atoms and hydrated electrons react with aniline under formation of the cyclohexadienyl type radical with absorption maximum at 355 nm and an extinction coefficient of 4100/M/cm. A similar radical formed by reaction of hydrogen atoms with the aniline cation has its absorption maximum at 31 0 nm and an extinction coefficient of 3200/M/cm. Hydrogen atoms react with the acid and neutral forms of aniline with rate constants of (1.3 ± 0.2 ) x 109/M/s and (2.9 ± 0.7) x 109/M/s, respectively. OH radicals react with aniline with a rate constant of (1.4 ± 0.3) x 1010/M/s under formation of the cyclohexadienyl radical with absorption maximum at 355 nm and the anilino radical with absorption maxima at 300 and 400 nm. The cyclohexadienyl radical decayed in a first order process with a rate constant of 1.4 x 105/s by elimination of NH3, whereas the anilino radical disappeared in a second order reaction under formation of hydrazobenzene. O- radicals react with aniline at pH 13.3 with a rate constant of (3.1 ± 0.6) x 109 under formation of anilino radicals. The reaction of OH radicals with the aniline cation produced the anilino radical cation with a rate constant of (4.8 ± 0.8) x 109 . The absorption maximum was placed at 415 nm, The cyclohexadienyl type radical with absorption maximum at 350 nm was also found in aqueous solutions of 2-amino-1,3-dimethylbenzene but was not formed in solutions of N,N' -dimethylaniline

  19. Solid state radiolysis of amino acids in an astrochemical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Cataldo, Franco, E-mail: franco.cataldo@fastwebnet.i [Istituto Nazionale di Astrofisica-Osservatorio Astrofisica di Catania, Via S. Sofia 78, 95123 Catania (Italy); Lupi Chemical Research, Via Casilina 1626/A, 00133 Rome (Italy); Angelini, Giancarlo [Istituto di Metodologie Chimiche, CNR, Via Salaria Km 29300, 00016 Monterotondo Stazione, Rome (Italy); Iglesias-Groth, Susana [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain); Manchado, Arturo [Instituto de Astrofisica de Canarias, Via Lactea s/n, E-38200, La Laguna, Tenerife (Spain) and CSIC (Spain)

    2011-01-15

    The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T{sub 1/2} for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6x10{sup 9} years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6x10{sup 9} years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant k{sub rac}.

  20. Low-energy (methanol radiolysis of astrochemical interest

    Science.gov (United States)

    Sullivan, Kristal K.; Boamah, Mavis D.; Shulenberger, Katie E.; Chapman, Sitara; Atkinson, Karen E.; Boyer, Michael C.; Arumainayagam, Christopher R.

    2016-07-01

    We report the first infrared study of the low-energy (methanol. Our goal is to simulate processes which occur when high-energy cosmic rays interact with interstellar and cometary ices, where methanol, a precursor of several prebiotic species, is relatively abundant. The interactions of high-energy radiation, such as cosmic rays (Emax ˜ 1020 eV), with matter produce large numbers of low-energy secondary electrons, which are known to initiate radiolysis reactions in the condensed phase. Using temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy (IRAS), we have investigated low-energy (5-20 eV) and high-energy (˜1000 eV) electron-induced reactions in condensed methanol (CH3OH). IRAS has the benefit that it does not require thermal processing prior to product detection. Using IRAS, we have found evidence for the formation of ethylene glycol (HOCH2CH2OH), formaldehyde (CH2O), dimethyl ether (CH3OCH3), methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and the hydroxyl methyl radical (·CH2OH) upon both low-energy and high-energy electron irradiation of condensed methanol at ˜85 K. Additionally, TPD results, presented herein, are similar for methanol films irradiated with both 1000 eV and 20 eV electrons. These IRAS and TPD findings are qualitatively consistent with the hypothesis that high-energy condensed phase radiolysis is mediated by low-energy electron-induced reactions. Moreover, methoxymethanol (CH3OCH2OH) could serve as a tracer molecule for electron-induced reactions in the interstellar medium. The results of experiments such as ours may provide a fundamental understanding of how complex organic molecules are synthesized in cosmic ices.

  1. Realistic assessment of direct radiolysis for synthetic fuels production using fusion radiation sources

    International Nuclear Information System (INIS)

    These studies indicate that synthetic fuel production by direct radiolysis cannot compete economically with other production methods. Low G-values and radiation contamination of products are given as reasons

  2. Development of pico-second pulse radiolysis system using SC probe light

    International Nuclear Information System (INIS)

    Pulse radiolysis is one of the most important and powerful means for detecting transient and relaxation phenomena and following their behavior in irradiated systems. We have been studying on pulse radiolysis system with Cs-Te photo cathode RF-gun at Waseda University. Stable short pulse white light generation is a key for the pulse radiolysis system. Recently, it can be generated by Photonic Crystal Fibre(PCF) in which laser field is high enough for producing nonlinear optical effect and produces a white spectra short pulse, called Super Continuum (SC) . Then we firstly tried to apply SC light as a candidate for a probe-light in pico-second pulse radiolysis system. Its S/N ratio and time resolution are 38, 22ps(rms) respectively. (author)

  3. Pulse radiolysis studies of fast reactions in molecular systems. Progress report, November 1976--October 1977

    International Nuclear Information System (INIS)

    Results from research in the following two areas are given: formation, properties, and reactivity of molecular ionic species in irradiated liquid systems; and pulse radiolysis of elementary reactions in protein function

  4. Design guideline to prevent the pipe rupture by combustion of radiolysis gases in BWR steam piping

    International Nuclear Information System (INIS)

    In late 2001, pipe rupture accidents due to fast combustion of radiolysis gas occurred in Japan and elsewhere's BWR power plants. TENPES began to set up the guideline as action to such a new problem to prevent accumulation and combustion of radiolysis gas in BWR steam piping. And then, the first edition of guideline was published in October 2005, and the 2nd edition in March 2007. Afterwards, the experimental study about combustion/detonation of radiolysis gas have been continued. And in March 2010, JANTI published the 3rd edition of the guideline. This is the report of the final edition of that guideline. According to this guideline, it became possible to design BWR's steam piping to prevent pipe rupture accident due to combustion of radiolysis gas. (author)

  5. Further details concerning the radiolysis of a carbon tetrachloride-benzene mixture (1961)

    International Nuclear Information System (INIS)

    The neutron-activation estimation of the chlorine fixed on DPPH during radiolysis of the mixture C6H6-CCl4 makes it possible to evaluate the contribution of the carbon tetrachloride to the overall phenomenon. (authors)

  6. Lateral spread of dose distribution by therapeutic proton beams in liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Abril, Isabel, E-mail: ias@ua.es [Departament de Física Aplicada, Universitat d’Alacant, E-03080 Alacant (Spain); Vera, Pablo de [Departament de Física Aplicada, Universitat d’Alacant, E-03080 Alacant (Spain); Garcia-Molina, Rafael [Departamento de Física – Centro de Investigación en Óptica y Nanofísica, Regional Campus of International Excellence “Campus Mare Nostrum”, Universidad de Murcia, E-30100 Murcia (Spain); Kyriakou, Ioanna; Emfietzoglou, Dimitris [Medical Physics Laboratory, University of Ioannina Medical School, GR-45110 Ioannina (Greece)

    2015-06-01

    We have calculated the lateral spread of the dose distribution of protons in liquid water by means of the SEICS (Simulation of Energetic Ions and Clusters through Solids) code, which properly accounts for the electronic stopping force (including energy-loss straggling), multiple elastic scattering with the target nuclei, dynamical electron charge-exchange processes and nuclear fragmentation reactions between the projectile and the nuclei of the target. Due to the multiple elastic scattering processes part of the proton energy may be deposited at a given lateral distance from the initial beam direction, which is quantified by the root mean square radius (r{sub rms}). We find in our simulations that the r{sub rms} follows a parabolic dependence as a function of the depth in the target and the quotient between the r{sub rms} at the Bragg peak and the depth of the Bragg peak is around 3% independently of the proton energy. A rather good agreement is obtained when comparing our results of r{sub rms} with experimental data and with other models.

  7. Simultaneous radiolysis, ECP, and crack growth modeling of components in BWR coolant systems

    International Nuclear Information System (INIS)

    An algorithm for assessing, theoretically, the effectiveness of hydrogen water chemistry (HWC) in Boiling Water Reactors (BWRS) is described. The algorithm, DAMAGE-PREDICTOR, contains facilities for estimating the concentrations of radiolysis products (in particular O2, H2, and H2O2), the electrochemical corrosion potential (ECP), and the kinetics of growth of a reference crack in sensitized Type 304SS, around the primary heat transport circuit (HTC) as a function of power level and the concentration of hydrogen added to the feedwater. The power level, in turn, determines various thermal hydraulic input parameters and the neutron and gamma energy deposition rate in the core and near-core regions. These input parameters are estimated using well-established algorithms, and the simulations have been carried out for full power conditions for two reactors that differ markedly in their responses to HWC. DAMAGE-PREDICTOR, when calibrated against recirculation oxygen levels in one plant, is found to successfully account for various plant data from both reactors (including steam line oxygen and hydrogen levels, ECP values from remote autoclaves attached to the recirculation system, and in-core ECP data) using a single set of model parameter values

  8. Gamma-radiolysis of dimethyl sulfoxide. II. Radiolysis yields and possible mechanisms; Gamma-Radiolisis del dimetilsulfoxido II. Rendimientos radioloticos y posibles mecanismos

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, M. C.; Barrera, R.

    1978-07-01

    As result of quantitative studies on gamma-radiolysis of DMSO at a dose range of 90-850 Mrads, constant G values have been obtained for the following radiolysis compounds: G(-DMSO) - 6.7 {+-}0.2; G(dimethyl sulphide) - 3.4 {+-}0.3; G(methane) - 0,75 {+-} 0.04; G(dimethyl disulphide) -0.33 {+-}0,03; G(tri methylsulphonium methanesulphonate) - 0.26 {+-} 0,01; G(methyl methanethiosulphonate) - 0,25 {+-}0.02; G(dimethyl sulphona)-0.21{+-}0.02; G(H{sub 2})-0.18{+-}0.02; and G(propane)--0.0092{+-}0.0007. Initial G values have been obtained for other identified compounds: Gi(ethane)-0,46; Gi(CO)-0.052; and Gi(CO{sub 2})-0.030. Possible mechanisms on the radiolysis process are proposed. (Author) 17 refs.

  9. Gas evolution and change in thickening properties of loosely crosslinked carboxyvinyl polyelectrolytes in γ radiolysis

    International Nuclear Information System (INIS)

    The authors establish that carbon oxides are the main gaseous products of gamma radiolysis of polyacrylic acid and of loosely crosslinked polyelectrolytes obtained by the copolymerization of acrylic acid with hexallylsaccharose or tetraallylpentaerythritol. Besides decarbonization, radiation-chemical processes of crosslinking and rupturing of originally formed crosslinks occur in the gamma radiolysis of loosely crosslinked polyelectrolytes, which reduces their thickening ability. These processes are more intensive in the presence of air

  10. Radiolysis of aqueous oxygen-free solutions of tryptophan at various pH values

    International Nuclear Information System (INIS)

    Gamma radiolysis of 10 sup(-2)M aqueous oxygen-free tryptophan solutions irradiated at various pH values and in a Nsub(2)O atmosphere was investigated. The values of the radiation losses of tryptophan and the yields of NHsub(3) were determined. Using HPLC with an electrochemical detector, the formation of hydroxylated radiation products of tryptophan was followed. The effect of pH on the radiolysis course is discussed. (author)

  11. Destabilization of water-organic dispersions under the influence of an electron beam

    Science.gov (United States)

    Metreveli, P. K.; Kholodkova, E. M.; Ponomarev, A. V.

    2016-07-01

    Influence of an irradiation on aqueous dispersions of starch, lignin and humic acids has been investigated using monoenergetic and multienergetic electron beams. As shown, coagulation and sedimentation of dispersed solids were initiated in the irradiated samples, however in neutral dispersions the multienergetic beam had a smaller effect compared to a monoenergetic beam. As supposed, the coagulation slowdown effect is caused by formation and repulsion of singlycharged and multiply-charged micelles during electron deceleration and capture directly in the bulk of dispersion.

  12. Molecular weight changes and scission and crosslinking in poly(dimethyl siloxane) on gamma radiolysis

    International Nuclear Information System (INIS)

    The molecular weight changes which occur on the γ-radiolysis of poly(dimethyl siloxane) under vacuum between 77 and 373 K and in air at 303 K have been investigated using triple detection GPC to obtain the complete molecular weight distributions for the irradiated samples and to determine the number and weight average molecular weights. The results have been interpreted in terms of the relative yields of scission and crosslinking. The total yields for crosslinking predominate over those for scission at all the temperatures investigated for radiolysis under vacuum. Based on a solid-state 29Si NMR analysis of PDMS irradiated under vacuum at 303 K, which yielded a value of G(Y) of 1.70, the values of G(S)=1.15±0.2 and G(H)=1.45±0.2 were obtained for radiolysis under vacuum at 303 K. For radiolysis in air at 303 K, crosslinking was also predominant, but the nett yield of crosslinking was much less than that observed for radiolysis under vacuum. Under the conditions of the radiolysis in air at 303 K, because of the low solubility of oxygen in PDMS, it is likely that the radiation chemistry is limited by oxygen diffusion

  13. Spectroscopic assessment of argon gas discharge induced radiolysis of aqueous adenine and thymine

    Energy Technology Data Exchange (ETDEWEB)

    Su Xi [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Shushanhu Road 350, Hefei 230031 (China); Huang Qing, E-mail: huangq@ipp.ac.cn [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Shushanhu Road 350, Hefei 230031 (China); Dang Bingrong [Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, Lanzhou 730000 (China); Wang Xiangqin; Yu Zengliang [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Shushanhu Road 350, Hefei 230031 (China)

    2011-12-15

    Ionizing radiation influences life profoundly for it can modify genetic materials. It is a long-standing task to investigate the interaction between energetic particles and DNA together with its components such as nucleotides, nucleosides and bases so as to predict and assess the potential biological effects. In this study, argon gas discharge was employed to produce energetic ions and electrons. The gas discharge caused the radiolysis of aqueous bases and the involved reactions were analyzed by means of spectroscopic tools including UV-vis absorption, fluorescence and Fourier transformation infrared (FTIR) spectroscopy, also assisted by liquid chromatography/mass spectrometry (LC/MS). It was found that the discharge resulted in the adenine-derived lesions such as 4,6-diamino-5-formamidopyrimidine, 8-OH-Ade and 2-OH-Ade in the radiolysis of aqueous adenine, as well as the thymine-derived lesions such as thymine glycol, 5-hydroxy-6-hydrothymine and/or 6-hydroxy-5-hydrothymine, 5-hydroxymethyluracil and 5-formyluracil in the radiolysis of aqueous thymine. The study of radio-sensitivity showed that adenine was more resistant to the discharge. The mechanisms of the involved reactions were studied in detail, confirming that the hydroxyl radical played a dominant role. - Highlights: > Effective new way to study radiolysis of bases via a home-made argon discharge apparatus. > Quantitative analysis of base radiolysis employing spectroscopic tools combined with HPLC/MS. > Discovery of different radiolysis effect compared with other forms of ionizing radiations.

  14. Spectroscopic assessment of argon gas discharge induced radiolysis of aqueous adenine and thymine

    International Nuclear Information System (INIS)

    Ionizing radiation influences life profoundly for it can modify genetic materials. It is a long-standing task to investigate the interaction between energetic particles and DNA together with its components such as nucleotides, nucleosides and bases so as to predict and assess the potential biological effects. In this study, argon gas discharge was employed to produce energetic ions and electrons. The gas discharge caused the radiolysis of aqueous bases and the involved reactions were analyzed by means of spectroscopic tools including UV-vis absorption, fluorescence and Fourier transformation infrared (FTIR) spectroscopy, also assisted by liquid chromatography/mass spectrometry (LC/MS). It was found that the discharge resulted in the adenine-derived lesions such as 4,6-diamino-5-formamidopyrimidine, 8-OH-Ade and 2-OH-Ade in the radiolysis of aqueous adenine, as well as the thymine-derived lesions such as thymine glycol, 5-hydroxy-6-hydrothymine and/or 6-hydroxy-5-hydrothymine, 5-hydroxymethyluracil and 5-formyluracil in the radiolysis of aqueous thymine. The study of radio-sensitivity showed that adenine was more resistant to the discharge. The mechanisms of the involved reactions were studied in detail, confirming that the hydroxyl radical played a dominant role. - Highlights: → Effective new way to study radiolysis of bases via a home-made argon discharge apparatus. → Quantitative analysis of base radiolysis employing spectroscopic tools combined with HPLC/MS. Discovery of different radiolysis effect compared with other forms of ionizing radiations.

  15. Chromium Waste Treatment from Leather Manufacture Using Electron Beam Radiation Technic

    International Nuclear Information System (INIS)

    Leather manufacture chromium waste treatment using chemical methods have an essential disadvantage, because of the production of the secondary contamination of wastes and separated sediments used by reagents. Therefore, a new technique is needed to solve this problem. The aim of the research to learn the advantages of electron beam radiation for chromium waste treatment. Water radiolysis can be produced by the interaction between electron beam and water or liquid substances. This phenomenon produces many reducing agents and ions that could reduce chromium concentrations in the liquid waste. Ethyl alcohol as a scavenger was added in the waste samples, then the pH of varied from 1, 4, 8 to 12, then were irradiated. Irradiation were done by Electron Beam Machine with dose 15, 25, and 35 kGy. After irradiation, chromium concentration in the samples were analyzed by AAS and UV-vis spectrophotometer. The results had shown that chromium could be reduced by high dose electron beam. The optimum reduction of chromium was achieved at liquid waste pH 8 and irradiation dose 35 kGy. (author)

  16. A water calorimeter for on-site absorbed dose to water calibrations in 60Co and MV-photon beams including MRI incorporated treatment equipment

    Science.gov (United States)

    de Prez, Leon; de Pooter, Jacco; Jansen, Bartel; Aalbers, Tony

    2016-07-01

    In reference dosimetry the aim is to establish the absorbed dose to water, D w, under reference conditions. However, existing dosimetry protocols are not always applicable for rapidly emerging new treatment modalities. For primary standard dosimetry laboratories it is generally not feasible to acquire such modalities. Therefore it is strongly desired that D w measurements with primary standards can be performed on-site in clinical beams for the new treatment modalities in order to characterize and calibrate detectors. To serve this need, VSL has developed a new transportable water calorimeter serving as a primary D w standard for 60Co and MV-photons including MRI incorporated treatment equipment. Special attention was paid to its operation in different beam geometries and beam modalities including the application in magnetic fields. The new calorimeter was validated in the VSL 60Co beam and on-site in clinical MV-photon beams. Excellent agreement of 0.1% was achieved with previous 60Co field calibrations, i.e. well within the uncertainty of the previous calorimeter, and with measurements performed in horizontal and vertical MV-photon beams. k Q factors, determined for two PTW 30013 ionization chambers, agreed very well with available literature data. The relative combined standard uncertainty (k  =  1) for D w measurements in 60Co and MV-photons is 0.37%. Calibrations are carried out with a standard uncertainty of 0.42% and k Q -factors are determined with a relative standard uncertainty of 0.40%.

  17. Detonating gas in boiling water reactors

    International Nuclear Information System (INIS)

    The radiation in the core region of Boiling Water Reactors (BWRs) decomposes a small fraction of the coolant into hydrogen and oxygen, a phenomenon termed radiolysis. The radiolysis gas partitions to the steam during boiling. A 1000 MWe BWR produces around 1.5 tons of steam, containing 25 grams of radiolysis gas, per second. Practically all of the radiolysis gas is carried to the condenser and is taken care of by the condenser evacuation system and the off-gas system. The operation of these systems has been largely trouble-free. Radiolysis gas may also accumulate when stagnant steam condenses in pressurized pipes and components as a result of heat loss. Under certain circumstances a burnable mixture of hydrogen, oxygen and steam may form. Occasionally, the accumulated radiolysis gas has ignited. These incidents typically result in deformation of the components involved, but overpressure bursts have also occurred. Radiolysis gas accumulation in steam systems was largely overlooked by BWR designers (a likely technical reason for this is given in the report) and the problem had to be addressed by utilities. Even though the problem was recognized two decades ago, the counter-measures of today seem not always to be sufficient. Pipe-burst incidents in a German and a Japanese BWR recently attracted attention. Also, damage to a pilot valve in the steam relief system of a Swedish BWR forced a reactor shut-down during 2002. The recent incidents indicate that counter-measures against radiolysis gas accumulation in BWRs should be reviewed, perhaps also improved. The present report provides a short compilation of basic information related to radiolysis gas accumulation in BWRs. It is hoped that the compilation may prove useful to utilities and regulators reviewing the problem

  18. Identification and evaluation of radiolysis products of irradiated chloramphenicol by HPLC-MS and HPLC-DAD

    International Nuclear Information System (INIS)

    The radiolysis products of chloramphenicol under γ-radiation sterilization were investigated systematically in the present study. Eight main radiolysis products were identified and quantified by HPLC-MS and HPLC-DAD, including two compounds that have never been reported. The minor radiolysis products were quantified, which shows that they are at the concentration levels below the threshold for identification. Carbon-carbon rupture reaction and oxidation reaction were proposed as the main radiolysis reactions of chloramphenicol powder. The applicability of γ-sterilization for chloramphenicol products was quantitatively evaluated with qualitative and quantitative data and the data were compared to the threshold requirements of international regulations for identification. It was concluded that toxicities of the radiolysis products of chloramphenicol produced by γ-radiation sterilization can be neglected, the radiolysis products are safe for human health from chemical view. (author)

  19. Gamma radiolysis and post-irradiation leaching of ion exchange resins

    International Nuclear Information System (INIS)

    The knowledge of the behavior under irradiation and in presence of water of Ion Exchange Resins (IER) is very necessary to predict their impact on the environment during the storage phase and in a possible deep geological disposal. The IER studied are the MB400 mixed bed resin and its 'pure' anionic and cationic components. The experimental strategy used in this work was based on the use of chemometric tools permitting to estimate the effect of the irradiation atmosphere, the dose rate, the absorbed dose and the leaching temperature. The gaseous and water-soluble radiolysis products were analyzed by gas Mass Spectrometry (MS) and Ion Chromatography (IC). The IER generated principally H2g, CO2g and amines for which quantities depended of the resin nature and the irradiation conditions. The analysis of solid irradiated resins was investigated by Fourier Transformed Infrared (FTIR) and Nuclear Magnetic Resonance (13C NMR) techniques. The last ones revealed structural modifications of the IER solid matrix in function of the experimental conditions. Their behavior in presence of water was studied during 143 days by characterization of the organic matter released after their post-irradiation leaching. The kinetics showed that all the water-soluble components were releasing at the first contact with water. The Total Organic Carbon (TOC) quantity released depends, according to the resin nature, either on the dose, either on the irradiation atmosphere. The dose rate has no effect on the degradation and the leaching of the MB400 resin, which behaved differently than its pure components. (author)

  20. Experimental study of the water-to-air stopping power ratio of monoenergetic carbon ion beams for particle therapy

    Science.gov (United States)

    Sánchez-Parcerisa, D.; Gemmel, A.; Jäkel, O.; Parodi, K.; Rietzel, E.

    2012-06-01

    Reference dosimetry with ionization chambers requires a number of chamber-specific and beam-specific calibration factors. For carbon ion beams, IAEA report TRS-398 yields a total uncertainty of 3% in the determination of the absorbed dose to water, for which the biggest contribution arises from the water-to-air stopping power ratio (sw, air), with an uncertainty of 2%. The variation of (sw, air) along the treatment field has been studied in several Monte Carlo works presented over the last few years. Their results were, in all cases, strongly dependent on the choice of mean ionization potentials (I-values) for air and water. A smaller dependence of (sw, air) with penetration depth was observed. Since a consensus on Iw, air and Iair has not yet been reached, the validity of such studies for clinical use cannot be assessed independently. Our approach is based on a direct experimental measurement of water-equivalent thicknesses of different air gaps at different beam energies. A theoretical expression describing the variation of the stopping power ratio with kinetic energy, sw,air(E), was derived from the Bethe-Bloch formula and fit to the measured data, yielding a coherent pair of Iw and Iair values with Iair/Iw = 1.157 ± 0.023. Additionally, the data from five different beam energies were combined in an average value of sw,air = 1.132 ± 0.003 (statistical) ± 0.003 (variation over energy range), valid for monoenergetic carbon ion beams at the plateau area of the depth dose distribution. A detailed uncertainty analysis was performed on the data, in order to assess the limitations of the method, yielding an overall standard uncertainty below 1% in sw,air(E). Therefore, when properly combined with the appropriate models for the fragment spectra, our experimental work can contribute to narrow the uncertainty margins currently in use in absorbed dose to water determination for dosimetry of carbon ion beam radiotherapy.

  1. Experimental determination of the absorbed dose to water in a scanned proton beam using a water calorimeter and an ionization chamber

    Science.gov (United States)

    Gagnebin, Solange; Twerenbold, Damian; Pedroni, Eros; Meer, David; Zenklusen, Silvan; Bula, Christian

    2010-03-01

    The absorbed dose to water is the reference physical quantity for the energy absorbed in tissue when exposed to beams of ionizing radiation in radiotherapy. The SI unit of absorbed dose to water is the gray (Gy = 1 J/kg). Ionization chambers are used as the dosimeters of choice in the clinical environment because they show a high reproducibility and are easy to use. However, ionization chambers have to be calibrated in order to convert the measured electrical charge into absorbed dose to water. In addition, protocols require these conversion factors to be SI traceable to a primary standard of absorbed dose to water. We present experimental results where the ionization chamber used for the dosimetry for the scanned proton beam facility at PSI is compared with the direct determination of absorbed dose to water from the METAS primary standard water calorimeter. The agreement of 3.2% of the dose values measured by the two techniques are within their respective statistical uncertainties.

  2. Analysis of. gamma. -radiolysis products of aqueous solutions of esters of aliphatic amino acids by the PMR method

    Energy Technology Data Exchange (ETDEWEB)

    Panin, V.I.; Sidorov, P.S.; Usatyi, A.F.

    1987-09-01

    The ..gamma..-radiolysis of aqueous solutions of methyl esters of aliphatic amino acids and peptides was investigated by the method of nuclear (proton) magnetic resonance (PMR). The resonance lines appearing in the PMR spectra of the irradiated systems were identified, and a conclusion was drawn about the molecular structure of the radiolysis products. The kinetics of the accumulation of radiolysis products was studied, and the values of their radiation yields were estimated.

  3. Perturbation correction factors for the NACP-02 plane-parallel ionization chamber in water in high-energy electron beams.

    Science.gov (United States)

    Verhaegen, F; Zakikhani, R; Dusautoy, A; Palmans, H; Bostock, G; Shipley, D; Seuntjens, J

    2006-03-01

    Recent dosimetry protocols for clinical high-energy electron beams recommend measurements of absorbed dose-to-water with a plane-parallel or cylindrical ionization chamber. For well-guarded plane-parallel ionization chambers, the ionization chamber perturbation factor in water, p(Q), has a recommended value of unity in all protocols. This assumption was investigated in detail in this study for one of the recommended ionization chambers in the protocols: the Scanditronix NACP-02 plane-parallel ionization chamber. Monte Carlo (MC) simulations of the NACP-02 ionization chamber with the EGSnrc code were validated against backscatter experiments. MC simulations were then used to calculate p(wall), p(cav) and p(Q) perturbation factors and water-to-air Spencer-Attix stopping powers in 4-19 MeV electron beams of a calibration laboratory (NPL), and in 6-22 MeV clinical electron beams from a Varian CL2300 accelerator. Differences between calculated and the currently recommended (Burns et al 1996 Med. Phys. 23 383-8) stopping powers, water-to-air, were found to be limited to 0.9% at depths between the reference depth z(ref) and the depth where the dose has decreased to 50% of the maximum dose, R50. p(wall) was found to exceed unity by 2.3% in the 4 MeV NPL calibration beam at z(ref). For higher energy electron beams p(wall) decreased to a value of about 1%. Combined with a p(cav) about 1% below unity for all energies at z(ref), this was found to cause p(Q) to exceed unity significantly for all energies. In clinical electron beams all three perturbation factors were found to increase with depth. Our findings indicate that the perturbation factors have to be taken into account in calibration procedures and for clinical depth dose measurements with the NACP-02 ionization chamber. PMID:16481689

  4. Perturbation correction factors for the NACP-02 plane-parallel ionization chamber in water in high-energy electron beams

    Energy Technology Data Exchange (ETDEWEB)

    Verhaegen, F [Medical Physics Department, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Quebec H3G1A4 (Canada); Zakikhani, R [Medical Physics Department, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Quebec H3G1A4 (Canada); DuSautoy, A [Radiation Dosimetry, National Physical Laboratory, TW11 0LW Teddington (United Kingdom); Palmans, H [Radiation Dosimetry, National Physical Laboratory, TW11 0LW Teddington (United Kingdom); Bostock, G [Radiation Dosimetry, National Physical Laboratory, TW11 0LW Teddington (United Kingdom); Shipley, D [Radiation Dosimetry, National Physical Laboratory, TW11 0LW Teddington (United Kingdom); Seuntjens, J [Medical Physics Department, McGill University, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Quebec H3G1A4 (Canada)

    2006-03-07

    Recent dosimetry protocols for clinical high-energy electron beams recommend measurements of absorbed dose-to-water with a plane-parallel or cylindrical ionization chamber. For well-guarded plane-parallel ionization chambers, the ionization chamber perturbation factor in water, p{sub Q}, has a recommended value of unity in all protocols. This assumption was investigated in detail in this study for one of the recommended ionization chambers in the protocols: the Scanditronix NACP-02 plane-parallel ionization chamber. Monte Carlo (MC) simulations of the NACP-02 ionization chamber with the EGSnrc code were validated against backscatter experiments. MC simulations were then used to calculate p{sub wall}, p{sub cav} and p{sub Q} perturbation factors and water-to-air Spencer-Attix stopping powers in 4-19 MeV electron beams of a calibration laboratory (NPL), and in 6-22 MeV clinical electron beams from a Varian CL2300 accelerator. Differences between calculated and the currently recommended (Burns et al 1996 Med. Phys. 23 383-8) stopping powers, water-to-air, were found to be limited to 0.9% at depths between the reference depth z{sub ref} and the depth where the dose has decreased to 50% of the maximum dose, R{sub 50}. p{sub wall} was found to exceed unity by 2.3% in the 4 MeV NPL calibration beam at z{sub ref}. For higher energy electron beams p{sub wall} decreased to a value of about 1%. Combined with a p{sub cav} about 1% below unity for all energies at z{sub ref}, this was found to cause p{sub Q} to exceed unity significantly for all energies. In clinical electron beams all three perturbation factors were found to increase with depth. Our findings indicate that the perturbation factors have to be taken into account in calibration procedures and for clinical depth dose measurements with the NACP-02 ionization chamber.

  5. The possible effects of alfa and beta radiolysis on the matrix dissolution of spent nuclear fuel

    International Nuclear Information System (INIS)

    The effects of oxidants on the retainment of actinides in a nuclear repository have been modelled by using an equilirium procedure. The oxidants are formed as a result of α- and #betta#-radiolysis when spent nuclear fuel is exposed to ground water. From an equilibrium point of view, the strongest reductants in the system (Zr, Pb and Cu) are expected to be oxidized first, leaving the actinoids in the oxidation states they have in the fuel matrix. This is expected to result in a negligible mobilization of the actinoids due to the very low solubility of the MO2 oxides. However, the formation of protective layers of oxides will most likely decrease the effectiveness of the metallic reducing agents. This will lead to an increased oxidation of the spent fuel which results in an increased actinoid mobilization. The results of the equilibrium calculations show that the oxidation of the fuel matrix results in the formation of UO2(OH)2(s) and to the formation of the soluble complex UO2(CO3)34. The transport of uranium is limited by the total concentration of carbonate in the aqueous phase. Neptunium may be quantitatvely solubilized as various Np(V) species and transported by ground water from the repository. Plutonium is retained at the repository site as insoluble PuO2. Only very small amounts are transported by ground water. The mobile actinoids may be reprecipitated when they encounter reducing conditions along the flow path. The conditions for repricipitation for typical ground water compositions have been modelled by using solubility - pe diagrams. (Authors)

  6. Pulse Radiolysis Using Very-high-energy Ions for Optimizing Cancer Therapy.

    Science.gov (United States)

    Getoff, Nikola

    2016-01-01

    Cancer therapy by means of high-energy ions is very efficient. As a consequence of the linear-energy-transfer effect only a negligible part of the produced free radicals can escape combination processes to form molecular products and to cause undesired side processes. Positrons (e⁺) and γ-rays, generated by the nuclear interaction of high-energy ions in the medium, serve in monitoring the radiation dose absorbed by the tumor. However, due to the dipole nature of water molecules a small proportion of thermalized positrons (e⁺th) can become solvated (e⁺aq). Hence, they are stabilized, live longer and can initiate side reactions. In addition, positronium (Ps), besides solvated electrons (e⁺aq), can be generated and involved in the reaction mechanisms. For a better understanding of the reaction mechanisms involved and to improve cancer therapy, a time-resolved pulse radiolysis instrument using high-energy particles is discussed here. The proposed method is examined and recommended by CERN experts. It is planned to be realized at the MedAustron Radiation Therapy and Research Centre in Wiener Neustadt, Austria. PMID:26912822

  7. Favism inducing agents: a pulse radiolysis study of isouramil and convicine

    International Nuclear Information System (INIS)

    Isouramil and covicine, substances implicated in precipitating favic crises in glucose-6-phosphate dehydrogenase deficient individuals, have been studied in N2O-saturated aqueous solutions by pulse radiolysis, and the kinetics of the reactions of both substances with OH radicals were determined. The products of these reactions are addition intermediates absorbing above 330 nm. The decay of the intermediate(s) formed in the isouramil reaction is a biphasic one, while the decay of the corresponding intermediate for the convicine reaction is characterized by a single constant. By analogy to uracil, it is suggested that the OH radical is added to the double bond at either positions 5 or 6 of the pyrimidine ring forming two different intermediates. Each of these intermediates loses a molecule of water indicated by the observed biphasic decay reaction. For convicine on the other hand, position 5 is blocked by the O-gucosidic bond and the addition of the OH radical could take place only at position 6. Thus, a single intermediate is formed and its decay is a single-phase one. It has been shown that although free radicals could not be detected in the course of the reactions between isouramil and oxygen or with cellular components by electron paramagnetic resonance, isouramil can participate in a uni-electron transfer reacton and can form relatively stable intermediates. Thus, it is speculated that in the red blood cells isouramil could give rise to deleterious free radicals

  8. Interfacial radiolysis effects in tank waste speciation. 1998 annual progress report

    International Nuclear Information System (INIS)

    'The purpose of this program is to deliver pertinent, fundamental information that can be used to make technically defensible decisions on safety issues and processing strategies associated with storage and clean up of DOE mixed chemical and radioactive wastes. The radioactive and chemical wastes present in DOE underground storage tanks contain complex mixtures of sludges, salts, and supernatant liquids. These mixtures, which contain a wide variety of oxide materials, aqueous solvents, and organic components, are constantly bombarded with gamma quanta, beta and alpha particles produced via the decay of radioactive isotopes. Currently, there is a vital need to understand radiolysis of organic and inorganic species present in mixed waste tanks because these processes: (a) produce mixtures of toxic, flammable, and potentially explosive gases (i.e., H2, N2O and volatile organics) (b) degrade organics, possibly to gas-generating organic fragments, even as the degradation reduces the hazards associated with nitrate-organic mixtures, (c) alter the surface chemistry of insoluble colloids in tank sludge, influencing sedimentation and the gas/solid interactions that may lead to gas entrapment phenomena. This report summarizes the technical achievements of a 3-year project that is now in its 2nd year. Progress in three areas is reported: (1) radiation effects at NaNO 3 crystal interfaces, (2) reactions of organic complexants with NO2 in water, and (3) radiation effects in oxide particles.'

  9. Propagation of an ultra intense laser pulse in an under dense plasma: production of quasi monoenergetic electron beams and development of applications; Propagation d'une impulsion laser ultra-intense dans un plasma sous-dense: generation de faisceaux d'electrons quasi monoenergetiques et developpement d'applications

    Energy Technology Data Exchange (ETDEWEB)

    Glinec, Y

    2006-09-15

    This experimental study concerns the generation of electron beams with original properties. These electrons beams originate from the interaction of an ultra-intense and short laser pulse with a gas jet. Previously, these electron beams had a large divergence and a broad spectrum. A major improvement in this field was achieved when an electron beam with low divergence (10 mrad) and a peaked spectrum (170 MeV) was observed during this thesis, using a new single shot electron spectrometer. A parametric study of the interaction allowed to observe the evolution of the electron beam. Experiments have been carried out to deepen the characterization of the electron beam. The observation of transition radiation generated by the electrons at an interface shows that the electron beam interacts with the laser pulse during the acceleration. Radial oscillations of the electron beam around the laser axis, named betatron oscillations, were also observed on the electron spectra. Such a quasi-monoenergetic spectrum is essential for many applications. In order to justify the interest of this electron beam, several applications are presented: a sub-milli-metric gamma-ray radiography of dense objects, a dose profile of the electron beam comparable to present capabilities of photon sources for radiotherapy, a very short temporal profile useful for water radiolysis and the generation of a bright X-ray source with low divergence. (author)

  10. Pulse radiolysis study of some substituted thiophenols in aqueous solutions

    International Nuclear Information System (INIS)

    Spectral and kinetic properties of the transient species formed by the reaction of substituted thiophenols such as 4-methyl thiophenol (MTP) and thiosalicylic acid (TSA) with e-aq, H-atom, OH radicals and one electron oxidants, viz. N3 and Br-2 radicals and one-electron reductants such as CO2H and (CH3)2COH radicals have been studied by pulse radiolysis technique. One electron oxidation leads to the formation of phenylthiyl type of radicals (R- C6H4S·). OH radicals react with MTP by addition to the benzene ring as well as by one-electron oxidation to give both hydroxycyclohexadienyl type of radicals and CH3C6H4S· type radicals whereas in the case of TSA the 390 nm band which is due to the hydroxycyclohexadienyl type of radical was not observed. In acidic solutions H-atoms, COOH and (CH3)2COH radicals abstract H atom from the -SH group of MTP and produce a species which is identical to that obtained by OH radical reaction under the same conditions, thus acting as oxidants. Similar reactions were not observed in the case of TSA. The phenylthiyl type of radicals were found to be non-oxidising in nature

  11. Improvements in detection system for pulse radiolysis facility

    CERN Document Server

    Rao, V N; Manimaran, P; Mishra, R K; Mohan, H; Mukherjee, T; Nadkarni, S A; Sapre, A V; Shinde, S J; Toley, M

    2002-01-01

    This report describes the improvements made in the detection system of the pulse radiolysis facility based on a 7 MeV Linear Electron Accelerator (LINAC) located in the Radiation Chemistry and Chemical Dynamics Division of Bhabha Atomic Research Centre. The facility was created in 1986 for kinetic studies of transient species whose absorption lies between 200 and 700 nm. The newly developed detection circuits consist of a silicon (Si) photodiode (PD) detector for the wavelength range 450-1100 nm and a germanium (Ge) photodiode detector for the wavelength range 900-1600 nm. With these photodiode-based detection set-up, kinetic experiments are now routinely carried out in the wavelength range 450-1600 nm. The performance of these circuits has been tested using standard chemical systems. The rise time has been found to be 150 ns. The photo-multiplier tube (PMT) bleeder circuit has been modified. A new DC back-off circuit has been built and installed in order to avoid droop at longer time scales. A steady baselin...

  12. The γ radiolysis at room temperature of liquid deaerated isopropanol

    International Nuclear Information System (INIS)

    The main products formed in the room temperature γ radiolysis of liquid isopropanol, and their respective yields, are: hydrogen 3.8, methane 1.6, acetone 3.4, acetaldehyde 1.1, and pinacol 0.3. These results give a material balance in good agreement with the formula of isopropanol and lead to a value for the yield of decomposition: 5, 3. The absence of butanediol 2.3 shows that the acetaldehyde cannot come from the dismutation of hydroxyethyl radicals. The variations of the hydrogen yield in the neutral medium with the concentration of added electron scavengers may be explained in terms of the model proposed by Freeman and FAYADH which supposes the existence of spurs. The yield of solvated electrons diffusing into the bulk of the solution and also the ratios of rate constants for the reactions of the scavengers with the electrons may likewise be obtained on the basis of this model. Certain effects not foreseen by this model may result from the capture of electrons solvated or not, whose mode of disappearance in pure alcohol remains unknown. One may distinguish a yield of excited molecules of at least 2, of which 80 per cent lead to the production of molecular hydrogen and 20 per cent to that of molecular methane, and an ionization yield of 2. 2. The discussion of the various mechanisms which may lead to the formation of the products indicates that these yields may be higher than the values quoted. (author)

  13. Heterogeneous radiolysis of HCN adsorbed on a solid surface

    International Nuclear Information System (INIS)

    Hydrogen cyanide is a key molecule for chemical evolution studies because, when it is exposed to different sources of energy, it forms various compounds of biological importance. To understand the role of minerals in chemical evolution, a series of experiments was performed. First, the adsorption capacity of HCN on different surface minerals was studied; the results show that HCN is readily adsorbed onto the solids proposed (zeolite, serpentine, dolomite, and sodium montmorillonite), in particular zeolite and montmorillonite. Second, the radiolysis of HCN adsorbed on olivine (as an example of a mineral surface) was also followed; it was found that the rate of HCN decomposition by gamma irradiation is enhanced in the presence of the solid. The third series of studies show that organic material was produced in high abundance from HCN at high radiation doses. The radiolytic products included gases (CO2, NH4, and CO) and oligomeric materials that release carboxylic acids (succinic, malonic, citric, and tricarballylic acids) and amino acids upon acid hydrolysis. These experiments suggest that minerals could have participated actively in chemical evolution processes.

  14. Radiolysis and hydrolysis of magnetically assisted chemical separation particles

    International Nuclear Information System (INIS)

    The magnetically assisted chemical separation (MACS) process is designed to separate transuranic (TRU) elements out of high-level waste (HLW) or TRU waste. Magnetic microparticles (1--25 μm) were coated with octyl (phenyl)N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) dissolved in tributyl phosphate (TBP) and tested for removing TRU elements from acidic nitrate solutions. The particles were contacted with nitric acid solutions and Hanford plutonium finishing plant (PFP) simulant, irradiated with a high intensity 60Co γ-ray source, and evaluated for effectiveness in removing TRU elements from 2m HNO3 solutions. The resistance of the coatings and magnetic cores to radiolytic damage and hydrolytic degradation was investigated by irradiating samples of particles suspended in a variety of solutions with doses of up to 5 Mrad. Transmission electron microscopy (TEM), magnetic susceptibility measurements, and physical observations of the particles and suspension solutions were used to assess physical changes to the particles. Processes that affect the surface of the particles dramatically alter the binding sites for TRU in solution. Hydrolysis played a larger role than radiolysis in the degradation of the extraction capacity of the particles

  15. Aqueous gelatine gels as the medium of pulse radiolysis

    International Nuclear Information System (INIS)

    A pulse radiolysis study has been performed on aqueous solutions of photographic grade gelatine at temperatures of 0, 20 and 400C. Concentrations of gelatine were 0.5-10%. The main part of the project consists of study of solutions and gels containing in addition 0.01-0.02 M SCN- competing with gelatine molecules for OH radicals. The rate constant of the latter reaction was determined (8.5±1.2 x 1011 M-1s-1) and compared with the computed one on the assumption of additivity of rate constants of amino acids residues with OH(7.11 x 1011). No statistically significant influence of the rigid medium on the rate constant of Gel + OH was found vs the liquid solution. The influence of high macro-viscosity of solutions and of the rigidity of gels has been studied on the recombination reaction of (SCN)2- ion radicals. Even at highest concentrations of gelatine, the influence of the rigid medium on the diffusion of small species was low. Apparently these small probes do not ''see'' thick strings of triple helixes of gelatine molecules. Several implications of results are discussed. (author)

  16. Radiolysis and photolysis studies on active transient species of berberine.

    Science.gov (United States)

    Cheng, Ling-Li; Wang, Yu-Jia; Huang, Da-Hong; Yao, Si-De; Ding, Guo-Ji; Wang, Shi-Long; Jiao, Zheng

    2014-04-24

    In this paper, the photochemical and photobiological characters of the active radicals of berberine (BBR) was investigated for finding an efficient and safe photosensitizer with highly active transient products using in Photodynamic therapy (PDT) study. The active species of BBR was generated and identified by using pulse radiolysis method. In neutral aqueous solution, BBR react with hydrated electron and hydroxyl radical, forming the radical anion and neutral radical of BBR, and the related reaction rates were determined as 3.5×10(10) and 6.7×10(9) M(-1) s(-1), respectively. Further, the capability of BBR to photosensitize DNA cleavage was testified by laser flash photolysis (LFP) method, the results demonstrated that BBR neutral radical could react with guanine mononucleotide (K=1.9×10(9) M(-1) s(-1)) via electron transfer to give the guanine neutral radical. Additionally BBR selective cleavage single and double strand DNA at guanine moiety was observed. Finally, combining with the thermodynamic calculation, the possible photodamage mechanism of dGMP and DNA induced by BBR was clarified. PMID:24582336

  17. Microdosimetry of radiation fields from therapeutic C-12 beams in water: a study with Geant4 toolkit

    CERN Document Server

    Burigo, Lucas; Mishustin, Igor; Bleicher, Marcus

    2013-01-01

    We model the responses of Tissue-Equivalent Proportional Counters (TEPC) to radiation fields of therapeutic C-12 beams in a water phantom and to quasi-monoenergetic neutrons in a PMMA phantom. Simulations are performed with the Monte Carlo for Heavy Ion Therapy (MCHIT) model based on the Geant4 toolkit. The shapes of the calculated lineal energy spectra agree well with measurements in both cases. Measurements on the axis of a narrow C-12 beam with its width smaller than the TEPC diameter are studied in detail. The relation between LET and measured frequency-mean lineal energy yf is discussed. It is found that the choice of the nuclear fragmentation model used in MCHIT simulations has a relatively small influence on the calculated total lineal energy spectra. However, the shapes of the spectra measured with C-12 beams are better described by MCHIT calculations which take into account the production of delta-electrons. The validation of MCHIT with neutron beams gives us confidence in estimating the contribution...

  18. The study on the primary processes of radiation chemistry in liquid alkanes by means of picosecond pulse radiolysis

    International Nuclear Information System (INIS)

    The primary processes of radiation chemistry in liquid alkanes were studied by using picosecond pulse radiolysis. Especially, the geminate ion recombination, the formation process of excited states and ion-molecular reaction of radical cations were directly observed and the primary processes were discussed. Also, future picosecond and femtosecond pulse radiolysis to elucidate the unsolved problem in the primary processes was discussed. (author)

  19. Electron-beam distillation of natural polymers

    International Nuclear Information System (INIS)

    Pyrolysis of cellulose, lignin, and chitin may be upgraded by the use of an electron-beam irradiation. The radiation-thermal destruction mode does more probable production of liquid low-molecular-weight products instead of solid pyrolitic oligomers. Furans, methoxyphenols, and pyridines are dominant products of high-temperature radiolysis of cellulose, lignin, and chitin, respectively. The mechanism of chain destruction of natural polymers is considered. - Highlights: • Pyrolysis of cellulose, lignin, and chitin upgraded by electron-beam distillation. • Distillation of cellulose results in furans obtaining. • Phenols and pyridines are dominant products from lignin and chitin, respectively

  20. Beam-Beam Effects

    OpenAIRE

    Herr, W; Pieloni, T.

    2016-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  1. Beam-Beam Effects

    CERN Document Server

    Herr, W

    2014-01-01

    One of the most severe limitations in high-intensity particle colliders is the beam-beam interaction, i.e. the perturbation of the beams as they cross the opposing beams. This introduction to beam-beam effects concentrates on a description of the phenomena that are present in modern colliding beam facilities.

  2. Primary species in irradiated water

    International Nuclear Information System (INIS)

    Despite the simple formula of water and the few stable products of radiolysis, the radiation chemistry of water is complex. This is a review of the species which exist between the moment of dose deposition and 10-7s later. 43 refs

  3. The new experiment WAGASCI for water to hydrocarbon neutrino cross section measurement using the J-PARC beam

    Science.gov (United States)

    Ovsiannikova, T.; Antonova, M.; Bronner, C.; Blondel, A.; Bonnemaison, A.; Cornat, R.; Cadoux, F.; Chikuma, N.; Cao, S.; Drapier, O.; Izmaylov, A.; Ichikawa, A. K.; Ferreira, O.; Favre, Y.; Gastaldi, F.; Gonin, M.; Hayashino, T.; Hosomi, F.; Hayato, Y.; Koga, T.; Kondo, K.; Kin, K.; Kudenko, Y.; Khabibullin, M.; Khotjantsev, A.; Minamino, A.; Mueller, Th A.; Mefodiev, A.; Mineev, O.; Nakamura, K.; Nakaya, T.; Noah, E.; Patel, N.; Quilain, B.; Rayner, M.; Seiya, Y.; Suvorov, S.; Yershov, N.; Yamamoto, M.; Yamamoto, K.; Yokoyama, M.

    2016-02-01

    The T2K (Tokai-to-Kamioka) is a long baseline neutrino experiment designed to study various parameters that rule neutrino oscillations, with an intense beam of muon neutrinos. A near detector complex (ND280) is used to constrain non-oscillated flux and hence to predict the expected number of events in the far detector (Super-Kamiokande). The difference in the target material between the far (water) and near (scintillator, hydrocarbon) detectors leads to the main non-canceling systematic uncertainty for the oscillation analysis. In order to reduce this uncertainty a new water grid and scintillator detector, WAGASCI, has been proposed. The detector will be operated at the J-PARC neutrino beam line with the main physics goal to measure the charged current neutrino cross section ratio between water and hydrocarbon with a few percent accuracy. Further physics program may include high-precision measurements of different charged current neutrino interaction channels. The concept of the new detector will be covered together with the actual construction plan.

  4. A pulse radiolysis apparatus with a scanning linac and some experimental results

    International Nuclear Information System (INIS)

    The first set of pulse radiolysis apparatus in China with microsecond time resolution was built up at Beijing Radiation Center (Institute of Low Energy Nuclear Physics, Beijing Normal University). The radiation source is a 5-Mev s-band scanning Linac which is mainly used as a radiator for doing radiation processing technology studies in this laboratory. In order to use this Linac as a radiation source in pulse radiolysis, some special designs of electronic, mechanical, optical and sample-holding systems were taken. Several experiments on pulse radiolysis of aqueous solution have been done successfully proving that this apparatus is very useful in our attempt to combine the industrial applications of radiation with the basic research of radiation chemistry in this laboratory. (author)

  5. Pulse radiolysis apparatus with a scanning linac and some experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Zhongwei; Liu Andong; Tong Zhongliang; Song Yingxin; Hu Huadan; Sun Wanhua; Gu Hongchun; Zhou Ruiying

    1988-01-01

    The first set of pulse radiolysis apparatus in China with microsecond time resolution was built up at Beijing Radiation Center (Institute of Low Energy Nuclear Physics, Beijing Normal University). The radiation source is a 5-Mev s-band scanning Linac which is mainly used as a radiator for doing radiation processing technology studies in this laboratory. In order to use this Linac as a radiation source in pulse radiolysis, some special designs of electronic, mechanical, optical and sample-holding systems were taken. Several experiments on pulse radiolysis of aqueous solution have been done successfully proving that this apparatus is very useful in our attempt to combine the industrial applications of radiation with the basic research of radiation chemistry in this laboratory.

  6. Physical approach to depth dose distributions in a water phantom irradiated by a teleisotope photon beam

    International Nuclear Information System (INIS)

    The physical basis of deposition of radiation dose within a homogeneous phantom irradiated by a monoenergetic photon beam has been studied in terms of photon attenuation and energy-absorption properties of the phantom material. A semi-empirical model based on the Klein--Nishina formula for Compton scattering, and the ratio of multiply scattered to singly scattered photon fluences, has been developed for the scatter dose component within a realistic phantom to determine the central-axial percent depth dose (PDD) and off-central-axis ratios (OCR). Differences between the predicted and measured values of PDD and OCR for cobalt-60 and cesium-137 beams are less than 3% for fields of equivalent-square-side less than 20 cm, and less than 5% for larger fields. Beam profiles of all field sizes can be well simulated by this model and reasonable agreement has been found between the predicted and tabulated values of scatter functions and the backscatter factor for cobalt-60 beams. This formulation involves no variable parameters, and is valid for all values of the source-to-surface distance, field length and width, and field shape. However, the algorithm developed is not suitable for routine multiple-field treatment planning because it requires large computer memory size

  7. Multiple gamma-ray beam and modality measurements for analysis of gas/oil/water pipe flows

    International Nuclear Information System (INIS)

    Measurement of multiphase pipe flow of gas, oil and water is not at all trivial and in spite of considerable achievements over the past two decades, important challenges remain. These are related to reducing measurement uncertainties arising from variations in the flow regime, improving long term stability and developing new means for calibration, adjustment and verification of the multiphase flow meters. This work focuses on the first two issues using gamma-ray attenuation and scattering. The feasibility of using multiple gamma-ray beams to identify the type of flow regime has been demonstrated. One 241Am source with principal emission at 59.5 keV is used because this relatively low energy enables efficient collimation and thereby shaping of the beams, as well as compact detectors. One detector is placed diametrically opposite the source whereas the second and eventually the third are positioned to the sides so that these beams are close to the pipe wall. The principle is then straight forward to compare the measured intensities of these detectors through that identify the instantaneous cross sectional gas-liquid distribution. Varying water salinity is another challenge for most multiphase flow meters because it affects volume fraction calculations based on gamma-ray, electrical conductance and other measurements. There have been a few approaches to solve this challenge and the method presented is based on combining the information from transmitted and scattered gamma-rays from a 241Am source. It has been shown that the gas volume fraction then can be determined independent of changes in the water salinity. (author)

  8. Comparison of the standards for absorbed dose to water of the NRC and the BIPM for accelerator photon beams

    Energy Technology Data Exchange (ETDEWEB)

    Picard, S.; Burns, D.T.; Roger, P.; Allisy-Roberts, P.J. [Bureau International des Poids et Mesures (BIPM), 92 - Sevres (France); McEwen, M.R.; Cojocaru, C.D.; Ross, C.K. [National Research Council of Canada, Ionizing Radiation Standards, Ottawa, ON (Canada)

    2010-12-15

    A comparison of the dosimetry for high-energy accelerator photon beams was carried out between the National Research Council of Canada (NRC) and the Bureau International des Poids et Mesures (BIPM) in June 2009. The comparison was based on the determination of absorbed dose to water for three radiation qualities. The comparison result, reported as a ratio of the NRC and the BIPM evaluations, is 0.997 at 6 MV, 1.001 at 10 MV and 0.994 at 25 MV, each with a relative standard uncertainty of 6 * 10{sup -3}. This result is the first of the ongoing BIPM.RI(I)-K6 comparison. (authors)

  9. Kinetic decay of H. in the radiolysis of tetracycline hydrochloride in powder form at 77 K

    International Nuclear Information System (INIS)

    Kinetic decay of paramagnetic species formed in the radiolysis of tetracycline hydrochloride in powder form at 77 K, shows that most of the H. is not able to migrate. But when H. acquires enough kinetic energy to migrate, it reacts preferentially with species different from its partner. The e- is not observed by ESR, at 77 K, although tetracycline hydrochloride is a chemical trap for e- in methanol, benzyl alcohol and alkaline aqueous solutions. In the radiolysis of tetracycline hydrochloride in powder form, the dimethylammonium group blocks H. abstraction reaction at 77 K. (author) 18 refs.; 5 figs

  10. Non-specificity of C-H bond rupture by γ radiolysis of 3-methylpentane glass

    International Nuclear Information System (INIS)

    Some authors using esr data claimed that there is a high selectivity for the rupture of a particular C-H bond after the radiolysis of solid branched alkanes. Using the identification of dimer isomers and very low total dose, we have established the identity of the trapped radical produced at 77 K by the radiolysis of 3-methylpentane, all the parent radicals are formed. If there is a different probability of breaking a particular C-H bond, the bond rupture is not much less selective in liquid than in the glassy state

  11. Pulse radiolysis and laser flash photolysis studies of synthetic and biopolymers

    International Nuclear Information System (INIS)

    The research work of pulse radiolysis and laser flash photolysis of synthetic and biopolymers which has been recently developed in the author's laboratory, is reviewed. The content of the paper is as follows; (1) radiation-induced ionic polymerization (2) photo-induced ionic polymerization (3) radiation-induced ionic polymerization in the presence of electron acceptor (4) laser photolysis study of copolymer of phenyl vinyl ketone and 2-vinylnaphthalene (5) photoviscosity of photochromic polymer (6) pulse radiolysis study of the reaction between active oxygen and hemoproteins (7) laser photolysis study of ferrous carbon monoxide complex of horseradish peroxidase. (auth.)

  12. ESR studies on the radiolysis of crystalline materials at cryogenic temperatures

    International Nuclear Information System (INIS)

    Presently we report our recent works on the radiolysis of crystalline materials that were studied mainly by ESR spectroscopy. They include A)hydrocarbon radiolysis using hydrocarbon mixed crystals with hydrocarbon having a different molecular chain length, alkenes, and with alkynes, B)the structure and reactions of extremely unstable ions of alkenes, alkynes, and halogenated alkanes trapped in crystalline matrices at cryogenic temperatures, and C)transfer and reactions of electrons, holes, and H atoms, and H/D isotope effects in the radiolytic reactions of hydrocarbons and H2O/D2O mixed crystals. (author)

  13. Interaction of a converging laser beam with a Ag colloidal solution during the ablation of a Ag target in water

    Science.gov (United States)

    Resano-Garcia, Amandine; Battie, Yann; Naciri, Aotmane En; Chaoui, Nouari

    2016-05-01

    We studied the nanosecond laser-induced shape modifications of Ag colloids exposed to a converging laser beam during the ablation of a Ag target in water. To this end, we performed a series of laser ablation experiments in which the laser energy was varied while all other parameters were kept constant. In addition to transmission electron microscopy (TEM), the shape distribution of the Ag nanoparticles was determined by modelling the extinction spectra of the final colloidal solutions using theoretical calculations based on shape distributed effective medium theory (SDEMT). From these calculations, two physical parameters named sphericity and dispersity were introduced and used to gauge the evolution of the shape distribution of the particles. As the laser energy on the target was increased from 5 to 20 mJ/pulse, an apparently abrupt modification of the shape distribution of the particles was evidenced by both TEM and SDEMT calculations. This change is explained in terms of competitive fragmentation, growth and reshaping processes. On the basis the heating–melting–vaporization model, we demonstrate how the competition between these processes, occurring at different locations of the converging beam, determines the shape distribution of the final product. We highlight the relevance of the fluence gradient along the beam path and the laser interaction volume on the laser-induced modifications of the suspended particles during the ablation process.

  14. Validation of nuclear models in Geant4 using the halo of a proton pencil beam stopping in water

    CERN Document Server

    Hall, David C; Paganetti, Harald; Gottschalk, Bernard

    2015-01-01

    A proton pencil beam is associated with a surrounding low-dose envelope, originating from nuclear interactions. It is important for treatment planning systems to accurately model this envelope when performing dose calculations for pencil beam scanning treatments, and Monte Carlo (MC) codes are commonly used for this purpose. This work aims to validate the nuclear models employed by the Geant4 MC code, by comparing the simulated absolute dose distribution to a recent experiment of a 177 MeV proton pencil beam stopping in water. Impressive agreement is observed over five orders of magnitude, with both the shape and normalisation well modelled. The normalisations of two depth dose curves are lower than experiment, though this could be explained by an experimental positioning error. The Geant4 neutron production model is also verified in the distal region. The entrance dose is poorly modelled, suggesting an unaccounted upstream source of low-energy protons. Recommendations are given for a follow-up experiment whi...

  15. Electrochemical behaviour of stainless steel under radiation and exposed to representative chemistry in pressurised water reactor conditions

    International Nuclear Information System (INIS)

    The dissertation focuses on the behaviour of stainless steel under irradiation and exposed to primary PWR conditions. The electrochemical potential of austenitic 316L stainless steel and the environmental parameters (hydrogen pressure, temperature, etc.,) have been measured continuously at high temperature (HT) and high pressure (HP) under irradiation, using a unique experimental HTHP working cell. Two sources of irradiation, proton and electron beams, have been employed in the study. A high similarity of electrochemical behaviour under both types of irradiations has been observed: (i) an oxidative potential response under irradiation (few tens of milli-volts); (ii) an increase in the hydrogen pressure reduces the oxidative potential response; (iii) a synergetic effect of thermal ageing and fluence leading to a decrease of the oxidative response under irradiation. The observations of the oxide film showed that without irradiation, metallic nickel in the inner and outer oxide films has been observed under a high hydrogen pressure. Under irradiation, um scale cavities (pits) have been observed in the strongly electron irradiated oxide film formed on 316L stainless steel. These defects are induced by the effect of irradiation of the passive film and water radiolysis. It is also shown that water radiolysis influences the PWR water chemistry by making it become a stronger oxidant at the oxide/solution interface. As a result, the release of metallic cations is increased and a-Fe2O3 hematite has been observed on the irradiated outer oxide film where cavities were formed. (author)

  16. Inedible cellulose-based biomass resist material amenable to water-based processing for use in electron beam lithography

    International Nuclear Information System (INIS)

    An electron beam (EB) lithography method using inedible cellulose-based resist material derived from woody biomass has been successfully developed. This method allows the use of pure water in the development process instead of the conventionally used tetramethylammonium hydroxide and anisole. The inedible cellulose-based biomass resist material, as an alternative to alpha-linked disaccharides in sugar derivatives that compete with food supplies, was developed by replacing the hydroxyl groups in the beta-linked disaccharides with EB-sensitive 2-methacryloyloxyethyl groups. A 75 nm line and space pattern at an exposure dose of 19 μC/cm2, a resist thickness uniformity of less than 0.4 nm on a 200 mm wafer, and low film thickness shrinkage under EB irradiation were achieved with this inedible cellulose-based biomass resist material using a water-based development process

  17. Evaluation of Streamwise Waveform on a High-Speed Water Jet by Detecting Trajectories of Two Refracted Laser Beams

    Directory of Open Access Journals (Sweden)

    Kazuhiro Itoh

    2011-01-01

    Full Text Available Free surface fluctuations on a high-speed water jet were measured by a laser beam refraction technique. This method can be used to obtain quantitative time-series data on local surface fluctuations. The developed system employs two pulsed laser diodes, and it uses a high-speed optical sensor to detect the instantaneous positions of the laser beams that are refracted at the free surface. Fluctuations in the slope angle are measured at two locations separated by 1.27 mm. The wave speed of each free surface wave, which is determined by the zero-upcrossing method, is experimentally evaluated by the cross-correlation method. A two-dimensional waveform is obtained by integrating the slope angle data. The local mean wavelength and mean wave steepness are evaluated for average jet velocities up to =10 m/s. Streamwise waveforms of the high-speed water jet at several locations exhibit appreciable asymmetry and have steep profiles.

  18. Determination of Absorbed Dose to Water in Megavoltage Electron Beams Using a Calorimeter-Fricke Hybrid System

    International Nuclear Information System (INIS)

    A water calorimeter-Fricke solution hybrid dosimetry system was developed at the National Research Council of Canada to be used for reference dosimetry for high energy electron beams in the energy range produced by medical linear accelerators. The system uses water calorimetry for higher energy beams of 18 MeV and 22 MeV, while Fricke dosimetry is used for the lower energies of 4 MeV, 8 MeV and 12 MeV. Fricke solution dosimetry was also used for 18 MeV and 22 MeV to determine the Fricke solution's ε·G(Fe3+) coefficient needed for calculations at lower energies. The deviation from linearity of the system in the dose range from 6 to 52 Gy was typically 0.2-0.3% for all energies, while the average repeatability for a single dosimeter was about 1%. As a practical application, the energy dependence of the response of a parallel-plate ionization chamber was investigated. It was found that at higher energies, the predictions were similar to those calculated by TG-51 and TRS 398, while for lower energies, differences were observed of up to 1%, consistent with new Monte Carlo and experimental investigations of chamber perturbation corrections,. (author)

  19. Radiolysis of astrophysical ice analogs by energetic ions: the effect of projectile mass and ice temperature.

    Science.gov (United States)

    Pilling, Sergio; Duarte, Eduardo Seperuelo; Domaracka, Alicja; Rothard, Hermann; Boduch, Philippe; da Silveira, Enio F

    2011-09-21

    An experimental study of the interaction of highly charged, energetic ions (52 MeV (58)Ni(13+) and 15.7 MeV (16)O(5+)) with mixed H(2)O : C(18)O(2) astrophysical ice analogs at two different temperatures is presented. This analysis aims to simulate the chemical and the physicochemical interactions induced by cosmic rays inside dense, cold astrophysical environments, such as molecular clouds or protostellar clouds as well at the surface of outer solar system bodies. The measurements were performed at the heavy ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds) in Caen, France. The gas samples were deposited onto a CsI substrate at 13 K and 80 K. In situ analysis was performed by a Fourier transform infrared (FTIR) spectrometer at different fluences. Radiolysis yields of the produced species were quantified. The dissociation cross section at 13 K of both H(2)O and CO(2) is about 3-4 times smaller when O ions are employed. The ice temperature seems to affect differently each species when the same projectile was employed. The formation cross section at 13 K of molecules such as C(18)O, CO (with oxygen from water), and H(2)O(2) increases when Ni ions are employed. The formation of organic compounds seems to be enhanced by the oxygen projectiles and at lower temperatures. In addition, because the organic production at 13 K is at least 4 times higher than the value at 80 K, we also expect that interstellar ices are more organic-rich than the surfaces of outer solar system bodies. PMID:21647477

  20. The unique facilities offered by γ radiolysis to understand polymerization kinetics

    International Nuclear Information System (INIS)

    Full text: One of the most important means of polymer formation involves initiation by free radicals. A subset of this, especially important in industry, is emulsion polymerization, whereby the polymerization process is dispersed in water: an environmentally-friendly 'solvent'. γ radiolysis as an initiation method for free-radical polymerization can give unique mechanistic information: it can penetrate opaque media (i.e., produce a uniform flux of radicals) yet can be switched off instantly, thereby enabling radical loss mechanisms to be investigated. It also gives a steady radical flux at any temperature, which is particularly convenient for looking at reactions at low temperatures, thereby giving the means of 'tuning out' complications that can occur at elevated temperatures. Data will be presented to show that this has enabled rate coefficients for a variety of free-radical processes to be obtained, often for the first time: for example, radical loss in emulsion polymerization by exit and by termination. A new method enables termination rate coefficients to be obtained by two completely independent means (one of which requires γ), thereby verifying the results from both. However, care must be taken for certain systems, such as those involving vinyl esters, where evidence has been obtained that unusual species are formed which undergo slow subsequent polymerization but rapid termination, thereby limiting the applications of the technique. The knowledge gained from these studies has been used to develop theories for these free-radical processes which are being further refined by testing with further experiments. Moreover, this knowledge has also been used to design new materials

  1. Holographic Measurements of Electron-Beam Dose Distributions Around Inhomogeneities in Water

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1976-01-01

    Dose distribution measurements made in a small quartz cell filled with water, and with an Al rod placed in the water are reported. The cell was irradiated vertically from above with monoenergetic 3 MeV electrons from a Van de Graaff accelerator. The holographic interferometric method previously...

  2. Photosynthetic pigments and model compounds studied by pulse radiolysis

    International Nuclear Information System (INIS)

    The photosynthetic pigments chlorophyll a and alltrans-β-carotene as well as the quinone model compound duroquinone have been studied in solution by pulse radiolysis combined with time-resolved absorption and resonance Raman spectroscopy. In benzene solution the excited triplet states of the subtrates were produced either directly in the case of duroquinone or by triplet energy transfer from triplet naphthalene in the case of chlorophyll a and β-carotene. All relevant rate constants involved in the reactions of the excited states in benzene were determined, including i) the rate constants for energy transfer from triplet naphthalene to chlorophyll a with k = (3.6+-0.6).109 M-1s-1 and β-carotene with k = (10.7+-1.2).109 M-1s-1 ii) the rate constants of triplet annihilation of chlorophyll a: (1.4+-0.3).109 M-1s-1, β-carotene: (3.6+-0.4).109 M-1s-1, duroquinone: (3.0+-0.6).109 M-1s-1. For β-carotene it is suggested that triplet-triplet annihilation produces the optically forbidden excited 1Asub(g) state. The first-order components of the triplet decays were strongly dependent upon irradiation dose in the case of naphthalene and duroquinone but apparently only slightly dependent on or independent or irradiation dose in the case of chlorophyll a and β-carotene. Apparent bimolecular rate constants for triplet quenching by radiolytically produced free radicals are determined. The triplet state of duroquinone is quenched by ground state duroquinone with a rate constant of (1.2+-0.3).106 M-1s-1. The excited triplet state of all-trans-β-carotene has been investigated by time-resolved resonance Raman spectroscopy. Six transient Raman bands at 965 cm-1, 1009 cm-1, 1125 cm-1, 1188 cm-1, 1236 cm-1 and 1496 cm-1 were observed. The spectra suggest that the C = C band order is decreased and that the molecule may be substantially twisted, presumably at the 15,151 band, in the triplet state. The radical anion of chlorophyll a with lambdasub(max) = 455 nm has been produced in

  3. High Linear Energy Transfer Radiolysis of Solvent Extraction Ligands

    Science.gov (United States)

    Pearson, Jeremy David

    study the effects of high LET radiation on organic solutions encountered in used nuclear fuel recycling processes. Understanding the effects of both high and low LET radiation on solvent extraction processes will facilitate early screening of novel ligand susceptibility to radiation induced degradation while also providing a more comprehensive picture of degradation encountered during radiolysis.

  4. Radiation-induced degradation of water pollutants - state of the art

    Energy Technology Data Exchange (ETDEWEB)

    Getoff, N. [Vienna Univ. (Austria). Inst. fuer Theoretische Chemie und Strahlenchemie]|[Ludwig-Boltzmann-Institut fuer Veterinaermedizinische Endokrinologie, Vienna (Austria)

    1996-04-01

    The radiation-induced decomposition of biological resistant pollutants in drinking as well as in wastewater is briefly reviewed. First, some important units, definitions etc., radiation sources, as well as dose-depth curves in water as functions of the electron energy and {sup 60}Co-{gamma}-rays are mentioned. Following is a schematical presentation of water radiolysis and of characteristics of primary free radicals. Then the degradation of some aliphatic and aromatic chlorinated compounds in the presence of air is presented. Some spectroscopic and kinetic data of transients resulting from chlorinated phenols are also quoted in order to illustrate and to explain the rather complicated degradation mechanisms. In this respect the synergistic effect of radiation and oxygen as well as that of ozone is also discussed. Finally, a scheme for technical application of high energy electron beam is presented. (author).

  5. Reaction of congo red in water after irradiation by pulsed intense relativistic electron beam

    International Nuclear Information System (INIS)

    The reaction of congo red, a well-known toxic azo dye, occurred after irradiation by a pulsed intense relativistic electron beam (PIREB). An aquation of congo red was irradiated by PIREB (2 MeV, 0.36 kA, 140 ns). After PIREB irradiation, the solution was measured by electrospray ionization-mass spectrometry and liquid chromatography/mass spectrometry. It was found that congo red underwent a reaction (77% conversion after five shots of PIREB irradiation) and the hydroxylated compounds of the dye were observed as reaction products. (author)

  6. Secondary Beam Fragments Produced by 200 and 400 MeV/u 12C6+ Ions in Water

    International Nuclear Information System (INIS)

    Based on the GEANT4 toolkit, we study the transportation of nucleons and nuclei in tissue-like media. The fragmentation of projectile nuclei and secondary interactions of produced nuclear fragments are considered. Livermore data is used to calculate electromagnetic interaction of primary and secondary charged particles. We validate the models using experimental data of 200 MeV/u and 400 MeV/u carbon ions, interacting with tissue equivalent materials of water. The model can well describe the depth-dose distributions in water and the doses measured for secondary fragments of certain charge and certain mass number. The secondary beam fragments produced by 200 MeV/u and 400 MeV/u 12C6+ ions in water are investigated using the model. When the primary nuclei are in water, several neutron production mechanisms are involved. The light charged particles (p, d, t, 3He and 4He) and fast neutrons contribute to the dose tail behind the Bragg peak. The 11C fragments which may be the most suitable nuclei for monitoring the energy deposition in carbon-ion therapy are also discussed

  7. Radiolysis study of the radical-like action mechanisms of an antioxidant: Sulfarlem

    International Nuclear Information System (INIS)

    Sulfarlem or p-anisyldithiolthione (ADT) is a sulfured heterocyclic compound which exhibits antioxidant properties. This work presents the quantitative study of the mono-electronic exchange mechanisms involved in this action. This study has been performed by gamma radiolysis and pulse radiolysis. The gamma radiolysis of ADT aerated ethanolic solutions has shown that O2. and RO2. radicals are not reactive towards ADT. In return, ADT is an efficient scavenger of R. radicals; the rate constant of this reaction being k (ADT + R.) = 6.7 x 104 mol-1.l.s-1. The pulse radiolysis experiments allowed the characterization of ADT reduction by the solvated electron (k (esolv- + ADT) = 2.3 x 1010 mol-1.l.s-1), the determination of the absorption spectrum of the reduced species A. (maximum wavelength = 580 nm) and the rate constant of its evolution (k (A. + A.) = 5.7 x 108 mol-1.l.s-1). An analogous study has been performed with ADO, an ADT oxidized derivative, which appeared to be a less efficient free radicals scavenger. (author)

  8. Radiolysis study of highly sensitive positive and self-developing polymeric resists

    International Nuclear Information System (INIS)

    Radiolysis studies were carried out on four different halogenated polymeric resists: (1) poly(haloalkyl methacrylates) and copolymers with methyl methacrylate, (2) copolymers of MCA and trihaloethyl methacylate (TFEMA, TCEMA), (3) poly(p-substituted α-methylstyrenes), and (4) poly(monochloracetaldehyde). Homopolymers and copolymers of various halogenated methacrylates were synthesized by radical bulk polymerization. Copolymer compositions were determined by elemental analysis, and the reactivity ratios of comonomers were obtained by Yezrielev's method. The molecular weights of the gamma-irradiated polymers were obtained by GPC. Thermal properties of these polymers have been studied by TGA and DSC. The radiolysis volatile products were analyzed by GC/MS. Quantitative ESR was used to identify the radicals as well as to obtained G(r) values. Based on the G values, ESR and GC/MS, the radiolysis mechanisms were proposed for each system. It has been found that dissociative electron capture plays a key role in the radiolysis of these halogenated methacrylate polymers, especially chlorine containing polymers. The dry-etching resistance of PMCAD can be enhanced by inducing crosslinking in unexposed areas of the resist material. A process similar to image reversal was proposed. Plasma etching resistance was determined by sample weight loss versus etching time. Addition of bisazidoformate crosslinkers improve the dry etching resistance of PMCAD substantially, but it also decreases the radiation sensitivity to certain degree

  9. DNA radiolysis in DNA-protein complex: a stochastic simulation of attack by hydroxyl radicals

    Czech Academy of Sciences Publication Activity Database

    Běgusová, Marie; Giliberto, S.; Gras, J.; Sy, D.; Charlier, M.; Spotheim Maurizot, M.

    2003-01-01

    Roč. 79, č. 6 (2003), s. 385-391. ISSN 0955-3002 R&D Projects: GA AV ČR IAA1048103 Institutional research plan: CEZ:AV0Z1048901 Keywords : radiolysis * DNA-protein complexes * hydroxyl radicals Subject RIV: BO - Biophysics Impact factor: 2.165, year: 2003

  10. Radioprotective effect of MPG and WR-2721 against gamma-radiolysis of human placental alkaline phosphatase

    International Nuclear Information System (INIS)

    Two-radioprotective drugs - MPG and WR-2721 have been found to protect human placental alkaline phosphatase against gamma radiolysis. Based on current literature and results obtained here free radical scavenging shielding of active sites and/or conformational change due to binding of the drug may be suggested as the possible mechanism of chemical radioprotection. (author)

  11. Radiolysis and corrosion of 238Pu-doped UO2 pellets in chloride brine

    Indian Academy of Sciences (India)

    M Kelm; E Bohnert

    2002-12-01

    Deaerated 5 M NaCl solution is irradiated in the presence of UO2 pellets with a-radiation from 238Pu. Experiments are conducted with 238Pu doped pellets and others with 238Pu dissolved in the brine. The radiolysis products and yields of mobilized U and Pu from the oxidative dissolution of UO2 are determined. Results found for radiolysis products and for the oxidation/dissolution of pellets immersed in Pu containing brine are similar to results for Pu doped pellets, where the radiation chemical processes occur only in the liquid layer of some 10 m thickness adjacent to the pellet. The yield of radiolysis products is comparable to earlier results, that of mobilized U from the pellets is < 1% of the total amount of oxidized species. Thus, the radiation chemical yield (-value) for mobilized hexavalent U is < 0.01 ions/100 eV. In spite of the low radiation yield for the corrosion, the rate of UO2 dissolution is higher than expected for the concentrations of long-lived oxidizing radiolysis compounds found in the solutions.

  12. Structural response of DN15-tubes under radiolysis gas detonation loads for BWR safety applications

    International Nuclear Information System (INIS)

    A U-shaped DN15 tube with 15 mm ID, 3 mm wall thickness was exposed to radiolysis gas (2H2+O2) detonation loads to investigate the structural stability of typical BWR tubes. Radiolysis gas at ambient temperatures was used at initial pressure up to 70 bar. The effect of transient detonation loads with peak pressures up to 1540 bar on the tube response was studied with strain gauges and simultaneous local pressure measurements. The strain measurements demonstrated that the tube material remained in the elastic response regime for initial radiolysis gas pressures of up to 20 bar. For the case with 30 and 70 bar initial pressure, local plastic deformations were observed under peak detonation pressures of 540 and 1540 bar, respectively. The measured strain values could be well explained with a simplified analysis of the elastic-plastic material behaviour under quasi-static loading conditions. Based on the measured strain data for the DN-15 tube, upper and lower bounds were estimated for the burst pressures of the failed pipes in the Brunsbuettel and the Hamaoka-1 NPP events. The experiments provide new data for the validation of structural dynamic codes and models of the response of typical BWR tubes under radiolysis gas detonation loads. (authors)

  13. BEAM applications to polymer materials

    International Nuclear Information System (INIS)

    Recently papers about beam applications to polymers have been increasing rapidly both in the fundamental and applied fields. Fairly large number of papers have been published in the fundamental aspects of radiation effects of beam applications to polymers such as pulse radiolysis and high density electronic excitation effects. A number of papers have been published in the more applied aspects of beam applications to polymers such as radiation processing and curing. The present paper describes recent beam applications to polymers. 1. Radiation Effects on Polymers; Radiation effects on polymers have been studied for more than 40 years. Most of work on radiation effects on polymers has been carried out by using high energy photon (gamma-ray) and electron beams, since polymers are sensitive to any kinds of ionizing radiation. Even non-ionizing radiation such as ultraviolet and visible light excites electronic excited states of polymers and then photo-chemical reactions of polymers are induced from the electronic excited states. Studies on radiation effects of other ionizing radiation on polymers have not been so popular for a long time. Recently application of new radiation such as ion beams to polymers have been worthy of remark in fields of advanced science and technology, since new radiation beams induce different radiation effects from those induced by high energy gamma-rays and electrons. 2. Beam Applications of Polymers; Recent progress in beam applications to polymers such as radiation processing and curing, x-ray and electron beam microlithography, and applications of new beams such as ion beams to polymers has been reviewed. (author)

  14. The influence of treatment with thiotepa, thyroxine and D3 vitamin and the effect of fast neutron radiolysis on walker tumor chromatin

    International Nuclear Information System (INIS)

    Anticancer drug thyotepa (10 mg/ kg) hormonal compound thyroxine (40 mg / kg) and D3 vitamin (30,000 IU / kg) have been administrated simply or associated to Wistar rats bearing Walker carcinosarcoma. The chromatin (the complex of DNA and proteins from nuclei) has been extracted from Walker tumor and submitted to fast neutron beams produced by deuterons (13 MeV) on thick Be target at an IPNE U-120 Cyclotron, in doses of 5-100 Gy. Thermal transition of chromatin fluorescence intensity of chromatin-ethidium bromide complexes and intrinsic fluorescence of chromatin have been analysed. Association of thiotepa with thyroxine and D3 vitamin produced a diminution of chromatin lesions induced by the cytostatic. Thus in the effects of fast neutrons radiolysis in chromatin significant differences occurred. These results could help to improve the methodology of associated chemotherapy-radiotherapy in clinical applications. (author)

  15. Production of intense beams of mass-selected water cluster ions and theoretical study of atom-water interactions

    CERN Document Server

    Wang, Z P; Reinhard, P -G; Suraud, E; Bruny, G; Montano, C; Feil, S; Eden, S; Abdoul-Carime, H; Farizon, B; Farizon, M; Ouaskit, S; Maerk, T D

    2009-01-01

    The influences of water molecules surrounding biological molecules during irradiation with heavy particles (atoms,ions) are currently a major subject in radiation science on a molecular level. In order to elucidate the underlying complex reaction mechanisms we have initiated a joint experimental and theoretical investigation with the aim to make direct comparisons between experimental and theoretical results. As a first step, studies of collisions of a water molecule with a neutral projectile (C atom) at high velocities (> 0.1 a.u.), and with a charged projectile (proton) at low velocities (< 0.1 a.u.) have been studied within the microscopic framework. In particular, time-dependent density functional theory (TDDFT) was applied to the valence electrons and coupled non-adiabatically to Molecular dynamics (MD) for ionic cores. Complementary experimental developments have been carried out to study projectile interactions with accelerated (< 10 keV) and mass-selected cluster ions. The first size distributio...

  16. Ultra-fast pulse radiolysis system combined with a laser photocathode RF gun and a femtosecond laser

    CERN Document Server

    Muroya, Y; Watanabe, T; Wu, G; Kobayashi, T; Yoshii, K; Ueda, T; Uesaka, M; Katsumura, Y

    2002-01-01

    In order to study the early events in radiation physics and chemistry, two kinds of new pulse radiolysis systems with higher time resolution based on pump-and-probe method have been developed at the Nuclear Engineering Research Laboratory, the University of Tokyo. The first one, a few picosecond (2 ps at FWHM) electron beam (pump) from an 18 MeV S-band Linac using a laser photocathode RF gun (BNL/KEK/SHI type: GUN IV) was operated with a femtosecond laser pulse (100 fs at FWHM), which also acted as the analyzing light (probe). The synchronization precision between the pump and the probe was 1.7 ps (rms). In a 1.0 cm sample cell, a time resolution of 12 ps was achieved. The second one, a picosecond (4 ps at FWHM) electron pulse from a 35 MeV S-band Linac employing a conventional thermionic gun with a sub-harmonic buncher, was synchronized with the femtosecond laser pulse, with a synchronization jitter of 2.8 ps (rms). A time resolution of 22 ps was obtained with 2 cm cell. This makes it possible to do the puls...

  17. Cost assessment of e-beam wastewater treatment

    International Nuclear Information System (INIS)

    Electron beam treatment of wastewater leads to purification by the decomposition of pollutants as a result of their reactions with highly reactive species formed from water radiolysis: hydrated electron, OH free radical and H atom. Sometimes such reactions are accompanied by the other processes, and the synergistic effect upon the use of combined methods such as electron beam with biological treatment, adsorption and others improves the effect of electron beam treatment of the wastewater purification. In the process of electron-beam treatment of wastewater there are utilized chemical transformations of pollutants induced by ionizing radiation. The key to the successful implementation of electron beam process in environmental protection depends on how to manage the economics in its application. To compete with other processes in economic evaluation, the electron beam system should be operated with cost-effective manners. To result in complete decomposition of the pollutants, sufficiently high absorbed doses are required. However, in real conditions of rather high content of pollutants in wastewater, high absorbed doses are not economically acceptable, and it is better to utilize the partial decomposition of pollutant as well as transformations of pollutant molecules that result in improving subsequent purification stages. To apply electron beam process to the treatment of industrial wastewater and disinfection of effluent from municipal wastewater plant, we accomplished the cost assessment together with the laboratory irradiation experiments. Cost assessments of industrial e-beam treatment plant for treating textile dyeing wastewater were carried out for the treatment capacity of 10 000 m3 per day. The total construction cost for this plant was USD 4M and the operation cost was not more than USD 1M per year and it was about USD 0.3 per each m3 of wastewater. Another study on the disinfection plant designed for the flow rate of 100 000 m3 effluent per day showed the

  18. Immobilization of bacterial proteases on water-solved polymer by means of electron beam

    International Nuclear Information System (INIS)

    Possibility of electron beam usage for proteases' immobilization on 1,4-polyalkylene oxide (1,4-PAO) was studied to obtain biologically active complex for multi-purpose usage. It is shown that immobilization of Bacillus Subtilis protease takes place due to free-radical linking of enzyme and carrier with formation of mycellium-like structures. Immobilization improves heat resistance of enzyme up to 60oC without substrate and up to 80oC in presence of substrate, widens range of pH activity in comparison with non-immobilized forms. Immobilized proteases do not contain peroxides or long-live radicals. Our results permitted to create technologies for production of medical and veterinary preparations, active components for wool washing agents and leather fabrication technology. (Author)

  19. Effect of the Bethe surface description on the electronic excitations induced by energetic proton beams in liquid water and DNA

    Science.gov (United States)

    Abril, Isabel; Denton, Cristian D.; de Vera, Pablo; Kyriakou, Ioanna; Emfietzoglou, Dimitris; Garcia-Molina, Rafael

    2010-06-01

    The irradiation of biological systems by energetic ion beams has multiple applications in medical physics and space radiation health, such as hadrontherapy for cancer treatment or protection of astronauts against space radiation. Therefore, for a better control and understanding of the effects of radiation damage in living tissues, it is necessary to advance an accurate description of the energy loss from the ion beam to the target. In the present work we use the dielectric formalism to calculate the probability for an energetic proton to produce electronic excitations in two targets of high biological interest, namely, liquid water and DNA. Also, the mean energy of the electronic excitations in these targets is found as a function of the incident proton energy. The electronic response of the target, characterized by its energy-loss function (ELF), is described by several models that fit the available experimental optical data (at zero momentum transfer), but use different approaches to obtain the Bethe surface, that is, to extend the ELF to any energy and momentum transferred.

  20. Travel-time sensitivity kernels versus diffraction patterns obtained through double beam-forming in shallow water.

    Science.gov (United States)

    Iturbe, Ion; Roux, Philippe; Virieux, Jean; Nicolas, Barbara

    2009-08-01

    In recent years, the use of sensitivity kernels for tomographic purposes has been frequently discussed in the literature. Sensitivity kernels of different observables (e.g., amplitude, travel-time, and polarization for seismic waves) have been proposed, and relationships between adjoint formulation, time-reversal theory, and sensitivity kernels have been developed. In the present study, travel-time sensitivity kernels (TSKs) are derived for two source-receiver arrays in an acoustic waveguide. More precisely, the TSKs are combined with a double time-delay beam-forming algorithm performed on two source-receiver arrays to isolate and identify each eigenray of the multipath propagation between a source-receiver pair in the acoustic waveguide. A relationship is then obtained between TSKs and diffraction theory. It appears that the spatial shapes of TSKs are equivalent to the gradients of the combined direction patterns of the source and receiver arrays. In the finite-frequency regimes, the combination of TSKs and double beam-forming both simplifies the calculation of TSK and increases the domain of validity for ray theory in shallow-water ocean acoustic tomography. PMID:19640037

  1. The application of the electron beam process in water and wastewater treatment: Fundamental and applied studies

    International Nuclear Information System (INIS)

    We have undertaken a three phase research project that has as the overall goal to better understand the application of the EB process to water, wastewater and sludge treatment. We have conducted studies to examine bimolecular rate constants for several halogenated methanes, several of which are common disinfection by-products when chlorination is practised. The second phase examines the ability to destroy odour causing compounds, we have selected thioanisole as the model compound, in wastewater and sludge treatment. The third phase of our study is to better understand the destruction mechanism and kinetic modelling of the fuel oxygenate, methyl tert-butyl ether, a common ground water contaminant in the US. We report here several new and re-evaluated bimolecular rate constants and the results of large scale EB treatment of water containing the compounds under study. ( author)

  2. Effects of electron beam irradiation combined with hot water immersion treatment for shelf life extension of bananas

    International Nuclear Information System (INIS)

    A study of the effects of minimal processing treatments, both individually or in combinations, was carried out in order to extend the shelf life and to improve the quality of bananas. Pre climacteric bananas at light full three-quarter grade, were either treated with hot water immersion for 1-30 min at 45-55 degree C, or irradiated with electron beams (2.0 MeV, Van de Graaff accelerator), to a dose of 0.1-1.5 kGy. All fruit was stored at 21 ± 1 degree C and relative humidity of 85-95 %. There was no significant delay in ripening of fruit treated with hot water immersion at the above temperatures. Some damage to fruit particularly peel scalding at ends occurred at the higher temperatures (>50 degree C). The 50 degree C, 5 minutes immersion was selected for further study. Irradiation to 0.1-0.3 kGy delayed the ripening (up to 3 days) without affecting fruit quality. Doses greater than 0.4 kGy resulted in extensive discoloration and fruit splitting. No significant differences could be detected organoleptically between bananas irradiated at 0.15 kGy and the control. Results of the physico-chemical attributes of the bananas were reported for fruits at colour stage 5 and after 10 and 15 days of storage. The combination treatment of hot water immersion and irradiation at the above settings further extended the shelf life of the banana fruits

  3. Electron beam irradiated polyamide-6,6 films--II: mechanical and dynamic mechanical properties and water absorption behavior

    International Nuclear Information System (INIS)

    Electron beam irradiation of poly(iminohexamethylene-iminoadipoyl) (Polyamide-6,6) films was carried out over a range of irradiation doses (20-500 kGy) in air. The mechanical properties were studied and the optimum radiation dose was 200 kGy, where the ultimate tensile stress (UTS), 10% modulus, elongation at break (EB) and toughness showed significant improvement over the unirradiated film. At a dose of 200 kGy, the UTS was improved by 19%, the 10% modulus by ∼9% and the EB by ∼200% over the control. The dynamic mechanical properties of the films were studied in the temperature region 303-473 K to observe the changes in the glass transition temperature (Tg) and loss tangent (tan δ) with radiation dose. The storage modulus of the film receiving a radiation dose of 200 kGy was higher than the unirradiated film. The water uptake characteristics of the Polyamide-6,6 films were investigated. The water uptake was less for the films that received a radiation dose of 200 and 500 kGy than the unirradiated film. The role of crystallinity, crosslinking and chain scission in affecting the tensile, dynamic mechanical and water absorption properties was discussed

  4. Calculated depth-dose distributions for H{sup +} and He{sup +} beams in liquid water

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Molina, Rafael [Departamento de Fisica - CIOyN, Universidad de Murcia, Apartado 4021, E-30080 Murcia (Spain)], E-mail: rgm@um.es; Abril, Isabel; Denton, Cristian D. [Departament de Fisica Aplicada, Universitat d' Alacant, Apartat 99, E-03080 Alacant (Spain); Heredia-Avalos, Santiago [Departament de Fisica, Enginyeria de Sistemes i Teoria del Senyal, Universitat d' Alacant, Apartat 99, E-03080 Alacant (Spain); Kyriakou, Ioanna; Emfietzoglou, Dimitris [Medical Physics Laboratory, University of Ioannina Medical School, Ioannina 451 10 (Greece)

    2009-08-15

    We have calculated the dose distribution delivered by proton and helium beams in liquid water as a function of the target-depth, for incident energies in the range 0.5-10 MeV/u. The motion of the projectiles through the stopping medium is simulated by a code that combines Monte Carlo and a finite differences algorithm to consider the electronic stopping power, evaluated in the dielectric framework, and the multiple nuclear scattering with the target nuclei. Changes in projectile charge-state are taken into account dynamically as it moves through the target. We use the MELF-GOS model to describe the energy loss function of liquid water, obtaining a value of 79.4 eV for its mean excitation energy. Our calculated stopping powers and depth-dose distributions are compared with those obtained using other methods to describe the energy loss function of liquid water, such as the extended Drude and the Penn models, as well as with the prediction of the SRIM code and the tables of ICRU.

  5. Gas phase radiolysis and vacuum ultraviolet photolysis of heterocyclic organic compounds. Progress report, February 1, 1974--February 1, 1975

    International Nuclear Information System (INIS)

    In the γ radiolysis of tetrahydrofuran there are pronounced density effects in the pressure range from 0 to 50 Torr with the most important ion-pair yields decreasing as the pressure increases. The relative product yields of the radiolysis is compared with that of xenon photolysis. Possible mechanisms to explain the results obtained are discussed. The ion-pair yields from the γ radiolysis of the heterocyclic amines, ethylenimine, azetidine, pyrrolidine, and piperidine, are determined, and the pressure effects are evaluated. Reactions mechanisms are discussed. The vacuum ultraviolet photolysis products of thietane and tetrahydrothiophene are studied and compared with the γ radiolysis products. Reaction mechanisms are discussed. The status of the construction of a photoionization mass spectrometer and the measurement of the ionization efficiencies and extinction coefficients of organic compounds is reported. (U.S.)

  6. Transport calculations for a 14.8 MeV neutron beam in a water phantom

    International Nuclear Information System (INIS)

    A coupled neutron/photon Monte Carlo radiation transport code (MORSE-CG) has been used to calculate neutron and photon doses in a water phantom irradiated by 14.8 MeV neutrons from the Gas Target Neutron Source. The source-collimator-phantom geometry was carefully simulated. Results of calculations utilizing two different statistical estimators (next-collision and track-length) are presented

  7. Corrosion behavior of 316 L stainless steel simulated by studying the influence of the species produced in the radiolysis in tritiated aqueous solutions

    International Nuclear Information System (INIS)

    The corrosion of 316 L stainless steel in tritiated aqueous solutions was simulated by studying the influence of species produced or present in the radiolysis in these solutions. The species studied were nitrates, fluorides, nitrites, hydrogen peroxide and components of the steel, as well as the pH. The method used was voltammetry. The corroded or passivated surfaces were examined by scanning electron microscopy and the corrosion rates were determined by measuring the electrochemical impedance. The depletion of the component elements of the stainless steel at the surface was observed by X-ray fluorescence. From our results we propose methods to limit the corrosion in an industrial tritiated water installation by controlling the pH, the oxidation-reduction potential of the water and the voltage of the installation

  8. Treatment Of Wastewater For Reuse With Mobile Electron Beam Plant

    International Nuclear Information System (INIS)

    The use of alternative disinfectants to chlorine for the wastewater treatment has received increasing attention in recent years to treat either liquid or solids streams within wastewater treatment plants for pathogens and trace organics (TOrCs). Although several technologies have come to the forefront as an alternative to chlorine (e.g., ultraviolet [UV] and hydrogen peroxide), the majority of these technologies are chemically based, with the exception of UV. An attractive physical disinfection approach is by electron beam (EB) irradiation. EB treatment of wastewater leads to their purification from various pollutants. It is caused by the decomposition of pollutants as a result of their reactions with highly reactive species formed from water radiolysis: hydrated electron, OH free radical and H atom [Pikaev (1986)]. Sometimes methods such as EB with biological treatment, adsorption and others improve the effect of EB treatment of the wastewater purification. In the process of EB treatment of wastewater there are utilized chemical transformations of pollutants induced by ionizing radiation. At sufficiently high absorbed doses these transformations can result in complete decomposition (removal) of the substance. Under real conditions, i.e., at rather high content of pollutants in a wastewater and economically acceptable doses, partial decomposition of pollutant takes place as well as transformations of pollutant molecules that result in improving subsequent purification stages, efficiency of the process being notably influenced by irradiation conditions and wastewater composition [Woods and Pikaev (1994)]. (author)

  9. Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

    International Nuclear Information System (INIS)

    Design and installation has been completed for a state-of-the-art radiolysis/hydrolysis test loop system. The system is used to evaluate the effects of gamma radiolysis and acid hydrolysis on the stability and performance of solvent extraction process solvents. The test loop is comprised of two main sections; the solvent irradiation and hydrolysis loop and the solvent reconditioning loop. In the solvent irradiation and hydrolysis loop, aqueous and organic phases are mixed and circulated through a gamma irradiator until the desired absorbed dose is achieved. Irradiation of the mixed phases is more representative of actual conditions in a solvent extraction process. Additionally, the contact of the organic phase with the aqueous phase will subject the solvent components to hydrolysis. This hydrolysis can be accelerated by controlling the system at an elevated temperature. At defined intervals, the organic from the irradiation/hydrolysis loop will be transferred to the solvent reconditioning loop where the solvent is contacted with scrub, strip, and solvent wash solutions which simulate process flowsheet conditions. These two processes are repeated until the total desired dose is achieved. Since all viable solvent extraction components in an advanced fuel cycle must exhibit high radiolytic and hydrolytic stability, this test loop is not limited to any one solvent system but is applicable to all systems of interest. Also, the test loop is not limited to testing of process flowsheets. It is also a valuable tool in support of fundamental research on newly identified extractants/modifiers and the impact of gamma radiation on their stability in a dynamic environment. The investigation of the radiolysis of a TBP/n-dodecane process solvent in contact with aqueous nitric acid has been performed. These studies were intended to confirm/optimize the operability of the test loop system. Additionally, these data are directly applicable to numerous other solvent extraction

  10. Summary Report on Gamma Radiolysis of TBP/n-dodecane in the Presence of Nitric Acid Using the Radiolysis/Hydrolysis Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Dean R. Peterman; Bruce J. Mincher; Catherine L. Riddle; Richard D. Tillotson

    2010-08-01

    Design and installation has been completed for a state-of-the-art radiolysis/hydrolysis test loop system. The system is used to evaluate the effects of gamma radiolysis and acid hydrolysis on the stability and performance of solvent extraction process solvents. The test loop is comprised of two main sections; the solvent irradiation and hydrolysis loop and the solvent reconditioning loop. In the solvent irradiation and hydrolysis loop, aqueous and organic phases are mixed and circulated through a gamma irradiator until the desired absorbed dose is achieved. Irradiation of the mixed phases is more representative of actual conditions in a solvent extraction process. Additionally, the contact of the organic phase with the aqueous phase will subject the solvent components to hydrolysis. This hydrolysis can be accelerated by controlling the system at an elevated temperature. At defined intervals, the organic from the irradiation/hydrolysis loop will be transferred to the solvent reconditioning loop where the solvent is contacted with scrub, strip, and solvent wash solutions which simulate process flowsheet conditions. These two processes are repeated until the total desired dose is achieved. Since all viable solvent extraction components in an advanced fuel cycle must exhibit high radiolytic and hydrolytic stability, this test loop is not limited to any one solvent system but is applicable to all systems of interest. Also, the test loop is not limited to testing of process flowsheets. It is also a valuable tool in support of fundamental research on newly identified extractants/modifiers and the impact of gamma radiation on their stability in a dynamic environment. The investigation of the radiolysis of a TBP/n-dodecane process solvent in contact with aqueous nitric acid has been performed. These studies were intended to confirm/optimize the operability of the test loop system. Additionally, these data are directly applicable to numerous other solvent extraction

  11. Water resistance and surface morphology of synthetic fabrics covered by polysiloxane/acrylate followed by electron beam irradiation

    CERN Document Server

    El-Naggar, A M; Mohammed, S S; Alam, E A

    2003-01-01

    Different synthetic fabrics were treated by electron beam surface coating with two formulations based on polydimethylsiloxane (PDMS) and polystyrene (PS) or poly(methyl methacrylate) (PMMA) oligomers. The water resistance properties were investigated in terms of the percentage of water repellency and absorption. Also, the surface coated fabrics were examined by scanning electron microscopy/microscope (SEM) connected to an energy dispersive X-ray (EDX) unit to determine the percentage atomic contents of elements. The results showed that the adhesion of the polysiloxane formulation to the surface depends largely on the kind of acrylate oligomer and textile fabric as indicated by the EDX analysis for silicon. In this regard, PDMS/PS formulation is more compatible with polyester and nylon-6 fabrics than PDMS/PMMA one. However, it was found that PDMS/PMMA formulation is more compatible with cotton/polyester blend than PDMS/PS. The SEM micrographs give further supports to the EDX analysis. On the basis of the perce...

  12. Uncertainties on measurements of absorbed-dose-to-water, from clinical high-energy eletron beams: a comparison with the IAEA protocols

    International Nuclear Information System (INIS)

    A pilot study was performed to verify the troubles involved in the implementation of dosimetric protocol TRS 398 for absorbed-dose-to-water, using clinical high-energy electron beams and to accomplish an detailed evaluation of uncertainty chain components associated to the measurement, which ones were not treated in the IAEA protocols, aimed the standardization of technical procedures. (author)

  13. Uncertainties on measurements of absorbed-dose-to-water, from clinical high- energy electron beams: a comparison with the IAEA protocols

    International Nuclear Information System (INIS)

    A pilot study was performed to verify the troubles involved in the implementation of dosimetric protocol TRS 398 for absorbed-dose-to-water, using clinical high-energy electron beams and to accomplish an detailed evaluation of uncertainty chain components associated to the measurement, which ones were not treated in the IAEA protocols, aimed the standardization of technical procedures. (author)

  14. Radiolysis studies of kappa carrageenan for bio based materials development

    International Nuclear Information System (INIS)

    Kappa (κ-) carrageenan oligomers are known to have several biological activities such as anti-HIV, anti-herpes, anti tumor and antioxidant properties. Recent progress in the development of radiation modified κ-carrageenan has resulted in new applications such as plant growth promoter, radiation dose indicator and hydrogels for wound dressing. This study would investigate on the changes in chemical structure, gelation and conformational transition behavior and molecular size of κ-carrageenan at doses from 0 to 200 kGy and would be correlated to these functions for the development of bio-based materials. Pulse radiolysis studies on κ-carrageenan was carried out to determine what transient species directly affects the degradation rate of κ-carrageenan in aqueous solution. The results reveal that there is no seeming reaction of the hydrated electron with κ-carrageenan. OH reacts with κ-carrageenan at a fast rate of approximately 1.2 x 109M-1a-1. This value was influenced by conformational change from helix to coil by the addition of the metal ion Na+, reduction of molecular weight by the hydrolysis reaction and reduction of reactive sites by seasonally or irradiation. Most applications from the radiation degradation of polysaccharides started with the use of the ''hit and miss'' process where polysaccharides were irradiated at a certain dose range and finding out which dose is suitable for a specific function. Measurement of the radiation degradation yield (Gd) at different conditions can give an approximation of the Mw at an absorbed dose. This will allow the production of oligomers with a specified Mw. With the use of the Gd both in solid and in aqueous solution, one can also make a rough calculation whether it is more economical to irradiateκ-carrageenan in solid r in aqueous solution. Results of this experiment reveal that the radiation yields (Gd) of κ-carrageenan in solid and in aqueous (1%) were as follows: 2.5, 1.7 and 1.2 x 10-7 mol J-1 for solid in

  15. Chilled beam application guidebook

    CERN Document Server

    Butler, David; Gräslund, Jonas; Hogeling, Jaap; Lund Kristiansen, Erik; Reinikanen, Mika; Svensson, Gunnar

    2007-01-01

    Chilled beam systems are primarily used for cooling and ventilation in spaces, which appreciate good indoor environmental quality and individual space control. Active chilled beams are connected to the ventilation ductwork, high temperature cold water, and when desired, low temperature hot water system. Primary air supply induces room air to be recirculated through the heat exchanger of the chilled beam. In order to cool or heat the room either cold or warm water is cycled through the heat exchanger.

  16. Reactivity of H. formed in the radiolysis of benzyl alcohol containing tetracycline hydrochloride at 77 K+

    International Nuclear Information System (INIS)

    The radiolysis of tetracycline hydrochloride dissolved in benzyl alcohol was studied at 77 K by ESR. The H. and e- which are formed in the radiolysis of benzyl alcohol at 77 K migrate over a distance corresponding to about 95 and 995 molecules of solvent, respectively, before they are captured by the tetracycline hydrochloride solute. The migration of H. in neopentane matrix is more favoured than in benzyl alcohol matrix. When the mole ratio between solute and solvent is 1:10000, the reactivity of H. observed by ESR is the following: a) 20% of H. reacts preferentially with solute; b) 80% of H. reacts exclusively with the solvent in the first collision. (author)

  17. Radiolysis as a solution for accelerated ageing studies of electrolytes in Lithium-ion batteries

    Science.gov (United States)

    Ortiz, Daniel; Steinmetz, Vincent; Durand, Delphine; Legand, Solène; Dauvois, Vincent; Maître, Philippe; Le Caër, Sophie

    2015-04-01

    Diethyl carbonate and dimethyl carbonate are prototype examples of eco-friendly solvents used in lithium-ion batteries. Nevertheless, their degradation products affect both the battery performance and its safety. Therefore, it is of paramount importance to understand the reaction mechanisms involved in the ageing processes. Among those, redox processes are likely to play a critical role. Here we show that radiolysis is an ideal tool to generate the electrolytes degradation products. The major gases detected after irradiation (H2, CH4, C2H6, CO and CO2) are identified and quantified. Moreover, the chemical compounds formed in the liquid phase are characterized by different mass spectrometry techniques. Reaction mechanisms are then proposed. The detected products are consistent with those of the cycling of Li-based cells. This demonstrates that radiolysis is a versatile and very helpful tool to better understand the phenomena occurring in lithium-ion batteries.

  18. A study on scavenging effects of Chinese medicine on superoxide anion radicals by pulse radiolysis

    Science.gov (United States)

    Fengmei, Li; Andong, Liu; Hongchun, Gu; Shaojie, Di

    1993-10-01

    A study on scavenging and dismutation effects on superoxide anion radical (·O -2) by using two Chinese antiaging medicine-Salvia Miltiorrhiza injection (S.M.) and Sulekang capsule (S.C.) were performed by pulse radiolysis. The absorption spectra of ·O -2 have been redetermined in radiolysis of aqueous solution of sodium format. The absorption maximum is at about 250nm. The results suggested that S.M. and S.C. can dismutate and scavenge ·O -2. The experimental scavenging rate of S.M. (150μg/ml) and S.C. (250μg/ml) were 89.6% and 69.5% respectively.

  19. A study on scavenging effects of Chinese medicine on superoxide anion radicals by pulse radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Li Fengmei; Liu Andong; Gu Hongchun; Di Shaojie (Beijing Normal Univ., BJ (China). Inst. of Low Energy Nuclear Physics)

    A study on scavenging and dismutation effects on superoxide anion radical ([center dot]O[sub 2][sup -]) using two Chinese antiaging medicines - Salvia miltiorrhiza injection (S.M.) and Sulekang capsule (S.C.) was carried out using pulse radiolysis. The absorption spectra of [center dot] OH[sub 2][sup -] was redetermined by radiolysis of an aqueous solution of sodium format. The absorption maximum is at about 250 nm. The results suggested that S.M. and S.C. can dismutate and scavenge [center dot]O[sub 2][sup -]. The experimental scavenging rates of S.M. (150[mu]g/ml) and S.C. (250[mu]g/ml) were 89.6% and 69.5% respectively. (author).

  20. Effect of heterogeneous catalysts on radiolysis of aqueous solutions of phenol

    International Nuclear Information System (INIS)

    Peculiarities of phenol aqueous solution radiolysis under conditions of continuous liquid flow through the layer of solid sorbent or various heterogeneous catalysts (MnO2, Pt, Ni, Ni-Pd), applied on activated carbons, are investigated. γ-radiation dose rate is 3 Gy/s, the dose is 0.36 kGy. Data on radiation-chemical yields of phenol destruction in the presence of sorbent and heterogeneous catalysts are presented. It is shown that during heterogeneous radiolysis of phenol in all the cases its more effective removal as compared with homogeneous one takes place; simultaneously, selective effect of the surface nature of the catalysts used on the mechanism of reactions and quantitative characteristics of the destruction process is observed