Radiolysis of supercritical water at 400 °C: density dependence of the rate constant for the reaction of hydronium ions with hydrated electrons

2019 ◽  
Vol 21 (18) ◽  
pp. 9141-9144 ◽  
Author(s):  
Jintana Meesungnoen ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Density Dependence ◽  
Rate Constant ◽  
Supercritical Water ◽  
Water Density ◽  
Hydronium Ions ◽  
Hydrated Electrons

The rate constant, k(eaq− + H3O+), for the reaction of hydronium ions with hydrated electrons in supercritical water at 400 °C has been evaluated as a function of water density over the range of 0.15–0.6 g cm−3.

Radiolysis of Supercritical Water at 400°C: A Sensitivity Study of the Density Dependence of the Yield of Hydrated Electrons on the (eaq−+eaq−) Reaction Rate Constant

2016 ◽  
Vol 2 (2) ◽  
Author(s):  
Sunuchakan Sanguanmith ◽  
Jintana Meesungnoen ◽  
David A. Guzonas ◽  
Craig R. Stuart ◽  
Jean-Paul Jay-Gerin
Keyword(s):  
Temperature Dependence ◽  
Density Dependence ◽  
Rate Constant ◽  
Supercritical Water ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Sudden Drop ◽  
Alkaline Water ◽  
Hydrated Electrons ◽  
Neutral Water

The temperature dependence of the rate constant (k) of the bimolecular reaction of two hydrated electrons (eaq−) measured in alkaline water exhibits an abrupt drop between 150°C and 200°C; above 250°C, it is too small to be measured reliably. Although this result is well established, the applicability of this sudden drop in k(eaq−+eaq−)) above ∼150°C to neutral or slightly acidic solution, as recommended by some authors, still remains uncertain. In fact, the recent work suggested that in near-neutral water the abrupt change in k above ∼150°C does not occur and that k should increase, rather than decrease, at temperatures greater than 150°C with roughly the same Arrhenius dependence of the data below 150°C. In view of this uncertainty of k, Monte Carlo simulations were used in this study to examine the sensitivity of the density dependence of the yield of eaq− in the low–linear energy transfer (LET) radiolysis of supercritical water (H2O) at 400°C on variations in the temperature dependence of k. Two different values of the eaq− self-reaction rate constant at 400°C were used: one was based on the temperature dependence of k above 150°C as measured in alkaline water (4.2×108  M−1 s−1), and the other was based on an Arrhenius extrapolation of the values below 150°C (2.5×1011  M−1 s−1). In both cases, the density dependences of our calculated eaq− yields at ∼60  ps and 1 ns were found to compare fairly well with the available picosecond pulse radiolysis experimental data (for D2O) for the entire water density range studied (∼0.15–0.6  g/cm3). Only a small effect of k on the variation of G(eaq−)) as a function of density at 60 ps and 1 ns could be observed. In conclusion, our present calculations did not allow us to unambiguously confirm (or deny) the applicability of the predicted sudden drop of k(eaq−+eaq−) at ∼150°C in near-neutral water.

Water density dependence of formaldehyde reaction in supercritical water

2004 ◽  
Vol 28 (2-3) ◽  
pp. 219-224 ◽  
Author(s):  
Mitsumasa Osada ◽  
Masaru Watanabe ◽  
Kiwamu Sue ◽  
Tadafumi Adschiri ◽  
Kunio Arai
Keyword(s):  
Density Dependence ◽  
Supercritical Water ◽  
Water Density

Effect of supercritical water density on the rate constant of aliphatic nitrocompounds decomposition

2005 ◽  
Vol 33 (3) ◽  
pp. 243-246 ◽  
Author(s):  
V.I. Anikeev ◽  
A. Yermakova ◽  
V.A. Semikolenov ◽  
M. Goto
Keyword(s):  
Rate Constant ◽  
Supercritical Water ◽  
Water Density

Effect of water density on the absorption maximum of hydrated electrons in sub- and supercritical water up to 400 °C

2008 ◽  
Vol 129 (11) ◽  
pp. 114511 ◽  
Author(s):  
Jean-Paul Jay-Gerin ◽  
Mingzhang Lin ◽  
Yosuke Katsumura ◽  
Hui He ◽  
Yusa Muroya ◽  
...  
Keyword(s):  
Supercritical Water ◽  
Absorption Maximum ◽  
Water Density ◽  
Effect Of Water ◽  
Hydrated Electrons

Die Reaktionen chlorierter Äthylene mit hydratisierten Elektronen und OH-Radikalen in wäßriger Lösung / The Reaction of Chlorinated Ethylenes with Hydrated Electrons and OH-Radicals in Aqueous Solution

1971 ◽  
Vol 26 (11) ◽  
pp. 1108-1116 ◽  
Author(s):  
R. Köster ◽  
K.-D. Asmus
Keyword(s):  
Rate Constant ◽  
Oh Radicals ◽  
Capture Process ◽  
Chlorinated Ethylenes ◽  
Diffusion Controlled ◽  
Hydrated Electrons ◽  
Cl Atoms ◽  
Type Radical ◽  
Cl Atom ◽  
Steric Hinderance

The reactions of chlorinated ethylenes with hydrated electrons and OH radicals have been investigated by using the method of pulse radiolysis. In addition γ-ray experiments were carried out. The reduction of the solutes occurs via a dissoziation electron capture process. The rate constant for the reaction of eaq⊖ with the more chlorinated compounds is essentially diffusion controlled (k= (1 - 2×1010 l-mole-1 sec-1). Vinylchloride and 1,2-trans-dichloroethylene react more slowly. This can be related to the higher stability of the C-Cl bond in these compounds.Hydroxyl radicals add to the C=C double bond of the chlorinated ethylenes. The rate constant for the reaction with vinylchloride was determined to 7.1 × 109 1 · mole-1 sec-1, and decreases with increasing degree of chlorination of the ethylenes. This effect is explained by the decreasing electron density on the C-atoms and steric hinderance. The hydroxyl radical always adds to the C-atom carrying the smallest number of Cl-atoms. In its reaction with 1,2-dichloro-, trichloro- and tetrachloroethylene a radical is produced with an OH group and a Cl-atom on the same C-atom. It eliminates HCl to form a C=O bond with k>7 × 105 sec-1. The type radical produced in this reaction has an optical absorption in the near UV (ε265 nm = (1-3)×103 1 · mole-1 cm-1).The OH radical addition products of vinylchloride and 1,1-dichloroethylene do not eliminate HCl and have no absorption in the visible and near UV.

Coupled Three-Dimensional Neutronics and Thermal-Hydraulics Analysis for SCWR Core Typical Transients

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Wang Lianjie ◽  
Lu Di ◽  
Zhao Wenbo
Keyword(s):  
Electric Power ◽  
Supercritical Water ◽  
Transient Analysis ◽  
Three Dimensional ◽  
Thermal Hydraulics ◽  
Water Density ◽  
Fuel Temperature ◽  
Control Rod ◽  
Reactor Protection System ◽  
Supercritical Water Cooled Reactor

Transient performance of China supercritical water-cooled reactor (SCWR) with the rated electric power of 1000 MWel (CSR1000) core during some typical transients, such as control rod (CR) ejection and uncontrolled CR withdrawal, is analyzed and evaluated with the coupled three-dimensional neutronics and thermal-hydraulics SCWR transient analysis code. The 3D transient analysis shows that the maximum cladding surface temperature (MCST) retains lower than safety criteria 1260 °C during the process of CR ejection accident, and the MCST retains lower than safety criteria 850 °C during the process of uncontrolled CR withdrawal transient. The safety of CSR1000 core can be ensured during the typical transients under the salient fuel temperature and water density reactivity feedback and the essential reactor protection system.

scholarly journals Hydrated electrons induce the formation of interstrand cross-links in DNA modified by cisplatin adducts

2020 ◽  
Vol 61 (3) ◽  
pp. 343-351
Author(s):  
B Behmand ◽  
A M Noronha ◽  
C J Wilds ◽  
J-L Marignier ◽  
M Mostafavi ◽  
...  
Keyword(s):  
Rate Constant ◽  
Gamma Rays ◽  
Gel Electrophoresis ◽  
Pulse Radiolysis ◽  
Interstrand Crosslinks ◽  
Radiosensitizing Effect ◽  
Hydrated Electrons ◽  
Interstrand Cross Links ◽  
Cross Links

Abstract Double-stranded oligonucleotides containing cisplatin adducts, with and without a mismatched region, were exposed to hydrated electrons generated by gamma-rays. Gel electrophoresis analysis demonstrates the formation of cisplatin-interstrand crosslinks from the cisplatin-intrastrand species. The rate constant per base for the reaction between hydrated electrons and the double-stranded oligonucleotides with and without cisplatin containing a mismatched region was determined by pulse radiolysis to be 7 × 109 and 2 × 109 M−1 s−1, respectively. These results provide a better understanding of the radiosensitizing effect of cisplatin adducts in hypoxic tumors and of the formation of interstrand crosslinks, which are difficult for cells to repair.

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