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[en] The report presents experimental studies on the formation of organic iodine in severe reactor accidents. The analyses were performed to evaluate the amount of alkaline chemical needed for effective pH control of containment water during the accidents. The formation of organic iodine in solutions used in the filtered venting system and the absorption of iodine compounds in the solutions were studied. Experiments for the formation of organic iodine on painted surfaces were also performed. (au)
[en] The reactivity of organylethynyl silatranylmethyl chalcogenides RC≡CYCH2Si(OCH2CH2)3N (R = Ph, Me3Si; Y = S, Se, Te) in reaction with methyl iodide was found to depend on the nature of the chalcogen atom Y, substituent R at the triple bond, and reaction conditions
[ru]Изучена реакционная способность органилэтинил(силатранилметил)халькогенидов RC≡CYCH2Si(OCH2CH2)3N (R = Ph, Me3Si; Y = S, Se, Te) при взаимодействии с метилиодидом в зависимости от природы атома халькогена Y, заместителя R у тройной связи и условий реакции
[en] A previously developed theory (Fabrikant 2007 Phys. Rev. A 76 012902) is applied to the calculation of dissociative electron attachment to CH3I molecules condensed at the surface of a Kr film. The effect of vibrational Feshbach resonance that strongly dominates attachment in the gas phase is strongly suppressed in the condensed phase. This leads to an order of magnitude reduction of the condensed-phase cross section as compared to the gas phase cross section, in spite of the lower resonance width and higher negative-ion survival probability in the condensed phase. The result agrees with recent measurements (Jensen and Sanche 2008 J. Chem. Phys. 129 074703), although the peak in the cross section as a function of the electron energy is narrower than the experimental peak. When the adsorbed molecules are covered by an additional Kr film on top, the dissociative attachment cross section grows rather fast. This result does not agree with the experiment for physisorbed CH3I covered by a 2 ML of Kr film, perhaps due to inaccuracy of the continuous-medium approximation employed in the calculations.
[en] Coherent control of fragmentation of CH3I using shaped femtosecond pulse train is investigated. The dissociation processes can be modulated by changing the separation of the shaped pulse train, and the yield of I+ under the irradiation of the optimal pulse is significantly increased compared with that using the transform-limited pulse. We discuss the control mechanism of dissociation processes with coherent interference in time domain. A three-pulse control model is proposed to explain the counterintuitive experimental results. (paper)
[en] With the deionized water as the absorbent, the solubility characteristics of the gaseous methyl iodide were studied under different temperature and pressure conditions, using a dynamic measuring method. The results show that within the range of experiment parameters, namely temperature is below 80℃ and pressure is lower than 0.3 MPa, the physical dissolution process of gaseous methyl iodide in water obeys Henry's law. The solubility coefficient under different temperature and pressure conditions was calculated based on the measurement results. Further research indicates that at atmospheric pressure, the solubility coefficient of methyl iodide in water decreases exponentially with the increase of temperature. While the pressure changes from 0.1 MPa to 0.3 MPa with equal interval, the solubility coefficient also increases linearly. The variation of the solubility coefficient with temperature under different pressure conditions all decreases exponentially. An equation is given to calculate the solubility coefficient of methyl iodide under different pressure and temperature conditions. (authors)
[en] The impregnation of active carbons is known to be a useful means of improving the ability of these carbons to retain methyl iodide which might be formed during the accidental release of fission products from a reactor. Some basic work was done on both impregnated and unimpregnated materials, which involved: (a) the texture: (b) the reaction of Mel with the impregnants; (c) the adsorption of Mel on the carbons under dry and wet conditions at different temperatures. It was found that the carbons are highly microporous. A large part of this porosity disappears on impregnation with organic amine; These impregnants react chemically with the methyl iodide, which is thereby fixed on the carbon. For carbon which is impregnated with KI, a rapid exchange reaction takes place between the methyl iodide and KI under both dry and wet conditions. Consequently most of the iodine activity can be removed from the gas. (author)
[en] Triethylene diamine (TEDA)-a widely-used impregnant for localization of iodine, possesses a few drawbacks, such as high steam pressure and low flash point, which restricts that activated carbon (AC) impregnated by TEDA can be only used below 390 K. Hexamethylene tetramine (HMTA) could be a substitute for TEDA because of its high flash point and low volatility. The impacts of a few parameters in the process of locating iodine by AC containing HMTA at 27 ℃ and 95%-96.5%(RH%) were tested. It is shown that appropriate quantity of impregnant (5%)and drying time (30 min) can improve the adsorption efficiency, whereas the decrease of pH and exposure to air of AC play the negative role. These preliminary results provide some experimental basis for further study of HMTA as impregnant for location of radioactive iodine. (authors)
[en] Charcoal filters impregnated with triethylenediamine (TEDA) are known to be efficient for the collection of volatile methyl iodide, which may be released under a hypothetical loss-of-coolant accident in a nuclear generating station. The structure and thermodynamic stability of the products of the TEDA-methyl iodide reaction have thus been studied using semi-empirical techniques. The reaction of TEDA with two molecules of methyl iodide leads to a quaternization reaction at each of the nitrogens. Moreover, it is shown that substitution of the hydrogens on TEDA with electron-donating groups can lead to enhanced stability of the quaternary ammonium reaction products. The semiempirical method PM3 (Parametric Method 3) was used as the basis for all calculations. Molecular systems and simulations were constructed using HyperChem 4.5 for Silicon Graphics workstations. Enthalpy determination and geometry optimization were some of the calculations performed on a system. (author)
[en] Electrochemical simulation of the cyclic voltammogram of a sterically hindered quinomethylene in dimethyl formamide (DMF) tetra-n-butylammonium perchlorate at mercury bead electrode was studied using two shareware simulation programs, namely, cyclic voltammetry simulation (CYSIM) and Electrochemical simulation package 2.4 (ESP 2.4). Two cathodic and two anodic peaks were analysed. ESP 2.4 took lesser time for simulations. (author)
[en] Highlights: • New scheme of I atoms REMPI. • Test of I atoms REMPI [(1 + 1′) + 1(1′)] for VIS-photodissociation of I2. • Velocity map imaging of I atoms arising in photodissociation of van der Waals complex CH3I-O2. • Confirmation of double spin-flip transition in van der Waals complex CH3I-O2. Photoexcitation of van der Waals (vdW) complex CH3I-O2 has been studied with velocity map imaging of I atoms arising in photodissociation. A new scheme of resonance-enhanced multiphoton ionization of iodine atoms has been applied with simultaneous use of UV and VIS radiation. The measured kinetic energy of I(2P3/2) atoms indicates photogeneration of precursor CH3I molecules via complex-specific channel with excitation energy expected for double spin-flip transition in complex CH3I-O2. The angular distribution for recoil directions of I(2P3/2) atoms coming from vdW complexes also corresponds to that expected for double spin-flip transition.