David R. McCracken

Atomic Energy (Canada)

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Estimation of rate constants for near-diffusion-controlled reactions in water at high temperatures

Journal of the Chemical Society Faraday Transactions (1990)

A. John Elliot David R. McCracken George V. Buxton Nicholas D. Wood

Rate constants measured over the temperature range 20–200 °C are reported for the following reactions: (a) reaction of the hydrated electron with oxygen, the proton, hydrogen peroxide, nitrate, nitrite, nitrobenzene and methyl viologen; (b) reaction of the hydroxyl radical with another hydroxyl radical and ferrocyanide; (c) reaction of the hydrogen atom with permanganate and oxygen. To evaluate methods of estimating rate constants at high temperatures these rate constants and others in the literature have been fitted to the following equation: kobs=kdiff/(1 +kdiff/kreact), where kobs is the measured rate constant for the bimolecular reaction in solution, kdiff is the encounter rate constant of the two reacting species, and kreact is the rate constant that would be measured if diffusion of the species was not rate influencing. With the exception of reactions of the hydrated electron with nitrate and nitrite ions and nitrous oxide, good fits have been obtained to the above equation, and the results demonstrate that few, if any, of the reactions which are pertinent to water radiolysis are truly diffusion controlled at elevated temperatures.

Nitrobenzene

Solvated electron

Reaction rate

Hydrogen atom

10.1039/ft9908601539

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Citations (291)

Poster 10. Decomposition of hydrogen peroxide under Candu coolant conditions

R. I. Haines David R. McCracken J. B. Rasewych

10.1680/wconrs5v1.15470.0050

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Citations (0)

Failure of Arrhenius equation for hydroxyl radical–bicarbonate ion reaction above 100 °C

Nature (1981)

David R. McCracken George V. Buxton

Bicarbonate

Atmospheric temperature range

Hydroxyl radical

Radiation chemistry

Reaction rate

10.1038/292439a0

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Citations (14)

An Ionization Chamber Study of Electron and Ion Decay in Irradiated Ammonia

Canadian Journal of Chemistry (1973)

David R. McCracken David A. Armstrong

Ionization chambers with plane parallel and coaxial electrodes have been used to study the ion and electron concentrations in ammonia subjected to 120 kvp X-ray pulses of 17 and 30 ms duration. Differences in the numbers of positive and negative ions collected on the application of pulses of high voltage imply that free diffusion of electrons to the cell walls occurs in the early part of the X-ray pulse until it is inhibited by the positive ion space charge. Thereafter, positive and negative ions decay at equal rates.The rate constant for the neutralization reaction[Formula: see text]at 1200 Torr of ammonia and 297°K was calculated to be 4.2 ± 1.0 × 10 −5 cm 3 ion −1 s −1 . However, unless extensive precautions are taken to remove electron-attaching impurities reactions between NH 4 + • nNH 3 ions and impurity negative ions are dominant. The results are discussed and compared to other work on electron–ion neutralization reactions.

Torr

10.1139/v73-622

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Citations (6)

ChemInform Abstract: PULSE RADIOLYSIS STUDY OF MONOVALENT CADMIUM, COBALT, NICKEL AND ZINC IN AQUEOUS SOLUTION. PART 2. REACTIONS OF THE MONOVALENT IONS

Chemischer Informationsdienst (1976)

George V. Buxton Robin M. Sellers David R. McCracken

George (robot)

10.1002/chin.197628020

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Citations (0)

Pulse radiolysis study of monovalent cadmium, cobalt, nickel and zinc in aqueous solution. Part 2.—Reactions of the monovalent ions

Journal of the Chemical Society Faraday Transactions 1 Physical Chemistry in Condensed Phases (1976)

George V. Buxton Robin M. Sellers David R. McCracken

Reactions of the monovalent metal ions Cd+, Co+, Ni+ and Zn+ with electron acceptors in neutral aqueous solution have been studied and three types identified: (a) addition M++ O2→ MO+2(M = Ni) M++ olefin →(M—olefin)+(b) oxygen atom transfer M++ N2O → MO++ N2(c) electron transfer M++ S2O2–8→ M2++ SO–4+ SO2–4. In reaction (b) when M= Co, long lived CoIII species are produced.Evidence is also presented for the oxidation of Co2+ by OH (k= 8 × 105 dm3 mol–1 s–1) and by SO–4(k∼ 2 × 106 dm3 mol–1 s–1) in neutral solution.

Qualitative inorganic analysis

10.1039/f19767201464

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Citations (53)

Postirradiation Dimensional Stability and Fission Product Behavior of Deliberately Defected UO₂Fuel at 200 and 400°C

Nuclear Technology (1985)

I.J. Hastings David R. McCracken E. Mizzan R.D. Barrand John R. Kelm

Twenty-four-hour sweep tests have been carried out in flowing air at 200 and 400°C on deliberately defected UO2 fuel elements with 2.5-yr discharge times. At 200°C there was no diametral change, but at 400°C, swelling and severe sheath cracking were observed. Neither short-lived fission products nor 134Cs, 137Cs, or 106Ru were detected above background. Maximum 85Kr release was ≤7.4 × 104 Bq (≤2 × 10−6 Ci).

Nuclear fission product

Nuclear Fuel

10.13182/nt85-a33652

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Citations (4)

Photon-electron energy deposition in CANDU reactor channels: Simulation and modelling

Radiation Physics and Chemistry (1996)

M.E.A. Abdelbaky Esam M.A. Hussein David R. McCracken

Deposition

10.1016/0969-806x(95)00164-s

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Citations (0)

The G-values of the primary species in 0.4 mol dm-3 H2SO4 irradiated at 300°C

International Journal of Radiation Applications and Instrumentation Part C Radiation Physics and Chemistry (1989)

A. John Elliot Denis C. Ouellette David L. Reid David R. McCracken

Mole

10.1016/1359-0197(89)90278-6

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Citations (2)

General discussion

Faraday Discussions of the Chemical Society (1977)

Azadvir Singh Brian Brocklehurst G. A. Salmon K. Selby J. Kroh

A. Singh, B. Brocklehurst, G. A. Salmon, K. Selby, J. Kroh, J. Mayer, J. Ceulemans, P. W. Percival, D. Meyerstein, R. M. Sellers, A. K. Pikaev, D. R. McCracken, M. C. R. Symons, A. Henglein, A. Bernas, C. von Sonntag, K.-D. Asmus, D. Schulte-Frohlinde, L. Dorfman, L. M. Dorfman, A. Hummel, L. Kevan, F. Williams, A. Płonka, W. A. Bernhard, A. Müller-Broich and M. Magat, Faraday Discuss. Chem. Soc., 1977, 63, 189 DOI: 10.1039/DC9776300189

10.1039/dc9776300189

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Citations (6)