Tritium β-Radiation-Induced Isotopic Exchange with Water Vapor

Yang, John Y.; Gevantman, L.H.

doi:10.1021/j100793a005

Cited by 15 publications

(14 citation statements)

References 2 publications

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“…The introduction in the mixture of a free radical scavenger would have as result the inhibition of the above reactions, and therefore the reduction in the water formation. Indeed such a scavenger effect has been observed by Yang and Gevantman [2], where the introduction in the gas mixture of nitric oxide resulted in a strong reduction in the water formation rate, down to 4% of the unscavenged one.…”

Section: Discussionmentioning

confidence: 74%

“…From the above sequence of reactions, the rate of water formation is given by the relation [2]. The systematic error in the above estimation was about f50%, since the accuracy of the rate constants was within f(10-40)%, and that of the intermediates was about f20%.…”

Section: Tritium Water and Helium Mixturementioning

confidence: 91%

“…In a tritium gaseous mixture the tritium molecules decay by emitting beta particles (electrons) with an average energy of 5.7 keV, and a maximum From [2]. energy of 18.6 keV [8].…”

Section: Physical and Chemical Processesmentioning

confidence: 99%

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Mechanism of HTO formation in gaseous tritium mixtures

Papagiannakopoulos

Easterly

1982

Int J of Chemical Kinetics

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The mechanisms for the conversion of molecular tritium gas to tritiated water are examined for tritium mixtures with (1) oxygen and nitrogen, (2) oxygen and argon, and (3) water and helium, for which previous experimental data exist. By analyzing results of these experiments in light of the radiation chemistry involved in a mixture of tritium and other gases, an understanding of the conversion mechanisms is reached. The formation of H and/or OH free radicals as intermediate species is of particular significance in the formation of HTO in that these radicals initiate a number of reactions which lead to the formation of water. These reactions are analyzed in terms of steady-state kinetics to obtain predictive models which can be judged against the experimental observations. For the three experimentally observed mixtures, model agreement is found to be within a factor of 2-3.

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Section: Discussionmentioning

confidence: 74%

Section: Tritium Water and Helium Mixturementioning

confidence: 91%

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Mechanism of HTO formation in gaseous tritium mixtures

Papagiannakopoulos

Easterly

1982

Int J of Chemical Kinetics

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“…При комнатной температуре в избытке инертного газа-разбавителя (общее давление 350-650 мм рт. ст., концентрация трития 50-700 мКи/л, содержание водяного пара 5-17,5 мг/л) эта реакция имеет второй порядок по концентрации трития, а от содержания водяного пара её скорость R практиче-ски не зависит [29]. При использовании гелия в качестве разбавителя…”

Section: радиационное автоокисление тunclassified

Radiation-Induced Gas-Phase Reactions of Tritium: Kinetics and Mechanisms

Sazonov¹,

Mendeleyev²

2013

PAST-TF

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Одной из актуальных проблем эксплуатации крупных термоядерных энергетических установок является проблема органически связанного трития (ОСТ), образующегося в техногенных средах в результате радиационно-индуцированных реакций. Для её решения необходимо иметь по возможности наиболее полную картину эволюции химических форм трития. Последнее подра-зумевает знание их кинетики и механизмов. Настоящая работа посвящена газофазным реакциям трития в виде молекулярного водорода и воды, происходящим при смешивании его с другими газами. Проведён обзор литературы разных лет, установлено, что имеющиеся к настоящему времени экспериментальные данные носят ограниченный характер. На ряде примеров (Т 2 + H 2 (D 2 ), N 2 , CH 4 и C 2 H 6 ) продемонстрировано, что использование методов квантовой химии в сочетании с теорией абсолютных скоростей реакций приводит к корректным оценкам скорости превращений и выхода продуктов. Сделан вывод о возможности и целесообразности дальнейшей работы по формированию базы данных по кинетике реакций трития, инициированных его распа-дом, с использованием теоретических расчётов и экспериментальных данных радиационной химии.Ключевые слова: тритий, радиационно-индуцированные реакции, меченые соединения, изотопный обмен, радиолиз, органи-чески связанный тритий (ОСТ). RADIATION-INDUCED GAS-PHASE REACTIONS OF TRITIUM: KINETICS AND MECHANISMS A.B. Sazonov D. Mendeleyev University of Chemical Technology of Russia, Moscow, RussiaOne of the actual problems of operating large thermonuclear power installations is the problem of organically bound tritium (OBT) formed in technical media as a result of the radiation-induced reactions. To solve the problem it is necessary to have the maximally fullest picture of evolution of chemical forms of tritium; the last means our knowledge of kinetics and mechanisms of corresponding chemical transformations. The present work concerns gas-phase reactions of tritium in the forms of molecular hydrogen and water occurring when they are mixed with other gases. The review of the literature of different years is presented; it is found that experimental data available to the present moment have a limited character. On a number of examples (Т 2 + H 2 (D 2 ), N 2 , CH 4 and C 2 H 6 ) it is shown that the use of methods of quantum chemistry in a combination with the theory of absolute reaction rates results in correct estimations of transformation rates and products yields. The conclusion is drawn on possibility and expediency of the further work on formation of database on kinetics of tritium reactions, initiated by its decay, with the use of theoretical calculations and experimental data of radiation chemistry.Key words: tritium, radiation-induced reactions, labeled compounds, isotope exchange, radiolysis, organically bound tritium (OBT). ВВЕДЕНИЕРазвитие ядерной и термоядерной энергетики связано с необходимостью решения проблемы гло-бального загрязнения биосферы радионуклидами, образующимися в реакторе при делении или получае-мыми путём активации мишеней в потоке нейтронов. Одним из так...

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“…Besides the risk of accidental release of elemental tritium to the environment, it may escape from the containment system by permeation through construction materials and by leakage from various parts of the system during normal operation [1]. It is oxidized to form tritiated water, which is 25000 times more hazardous than elemental tritium [2], via radiochemical [3], catalytic [4] and biochemical processes [5] as well as isotopic exchange with water vapor [6].…”

Section: Introductionmentioning

confidence: 99%

Acceleration of the UV‐stimulated HT oxidation by CCl₄

Hasegawa

Fusumae

Miyahara

et al. 1994

Journal of Environmental Science and Health . Part A: Environme

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The effects of air pollutants on UV-stimulated HT oxidation were studied by selecting CCl 4 as a model pollutant. Mixture gases consisting of H 2 +HT, O 2 and CCl 4 were irradiated with a high pressure mercury lamp. The reaction products were found to be HTO and TCl. The role of CCl 4 was evaluated by measuring the formation rate of HTO+TCl as a function of the partial pressure of CCl 4 . The reaction took place in two stages. During the first stage, the extent of the reaction increased almost linearly with time. During the second stage, the rate became faster with time, showing a similar feature to 282 HASEGAWA ET AL.autocatalytic reactions. It was found that those rates were considerably increased with the pressure of CCl 4 . In the case of 1.0 Torr, the rate of the first stage was 60 times greater than that of the UV-stimulated HT oxidation previously reported, and that of the second stage was about 10 times that of the first stage. As a whole, the CCl 4 -assisted UV-stimulated HT oxidation showed a 5×10 4 -5×10 5 times greater reaction rate than the ß ray-induced radiochemical HT oxidation. With the aid of computer simulation including 47 relevant elementary reactions, the enhanced acceleration of the reaction was understood as a result of the formation of new reaction paths such as Cl H HO 2 H 2 O and Cl H HO 2 OH H 2 O, which lacked in the UV-stimulated HT oxidation mechanism.

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Tritium β-Radiation-Induced Isotopic Exchange with Water Vapor

Cited by 15 publications

References 2 publications

Mechanism of HTO formation in gaseous tritium mixtures

Mechanism of HTO formation in gaseous tritium mixtures

Radiation-Induced Gas-Phase Reactions of Tritium: Kinetics and Mechanisms

Acceleration of the UV‐stimulated HT oxidation by CCl₄

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Tritium β-Radiation-Induced Isotopic Exchange with Water Vapor

Cited by 15 publications

References 2 publications

Mechanism of HTO formation in gaseous tritium mixtures

Mechanism of HTO formation in gaseous tritium mixtures

Radiation-Induced Gas-Phase Reactions of Tritium: Kinetics and Mechanisms

Acceleration of the UV‐stimulated HT oxidation by CCl4

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Product

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Acceleration of the UV‐stimulated HT oxidation by CCl₄