Water radiolysis and its effect upon in-reactor zircaloy corrosion

Burns, W. G.; Moore, Paul Β.

doi:10.1080/00337577608240827

Cited by 151 publications

(67 citation statements)

References 7 publications

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“…This irradiation results in the chemical decomposition (radiolysis) of water and leads to the formation of the short-lived reactive radicals e − aq (hydrated electron), H , OH, and HO 2 (or O 2 − , depending on pH) and the longerlived molecular products H 2 and H 2 O 2 (and eventually O 2 ). These species can promote corrosion, cracking, and hydrogen pickup both in the core and in the associated piping components of the reactor [1][2][3][4][5]. Theoretical calculations and chemical models of the radiation chemistry of water in the reactor core require the radiolytic yields (defined as the number of species formed or destroyed per 100 eV of energy absorbed [6,7]) of the primary species for both fast neutrons and γ-radiation.…”

Section: Introduction *mentioning

confidence: 99%

On the Temperature Dependence of the Rate Constant of the Bimolecular Reaction of Two Hydrated Electrons

et al. 2013

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Self-reaction of the hydrated electron Rate constant Yield of H 2 Linear energy transfer (LET) Monte Carlo track chemistry calculationsIt has been a longstanding issue in the radiation chemistry of water that, even though H 2 is a molecular product, its "escape" yield g(H 2 ) increases with increasing temperature. A main source of H 2 is the bimolecular reaction of two hydrated electrons (e − aq ). The temperature dependence of the rate constant of this reaction (k 1 ), measured under alkaline conditions, reveals that the rate constant drops abruptly above ~150°C. Recently, it has been suggested that this temperature dependence should be regarded as being independent of pH and used in hightemperature modeling of near-neutral water radiolysis. However, when this drop in the e − aq self-reaction rate constant is included in low (isolated spurs) and high (cylindrical tracks) linear energy transfer (LET) modeling calculations, g(H 2 ) shows a marked downward discontinuity at ~150°C which is not observed experimentally. The consequences of the presence of this discontinuity in g(H 2 ) for both low and high LET radiation are briefly discussed in this communication. It is concluded that the applicability of the sudden drop in k 1 observed at ~150°C in alkaline water to near-neutral water is questionable and that further measurements of the rate constant in pure water are highly desirable.

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Section: Introduction *mentioning

confidence: 99%

On the Temperature Dependence of the Rate Constant of the Bimolecular Reaction of Two Hydrated Electrons

et al. 2013

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“…Reaction (25) which is the predominant reaction above pH 12 is slower than reaction (23) or (24) because of the charge repulsion so that H 2 O 2 formation does not occur faster than at neutrality. Since hydroxyl radical formation with the neutral set is promoted less than with the alkaline set, the results obtained by the neutral set give more a conservative evaluation for the alkaline effect on the radiolysis of water.…”

Section: 5mentioning

confidence: 99%

“…The g-value and reaction set for the calculation were listed in Tables 4 3) and 5. [25][26][27][28] The ECP calculation was also carried out at three pH con- ditions, 7, 8, and 9 using the concentrations obtained by SIM-FONY. Details of the ECP model were is described previously.…”

Section: 5mentioning

confidence: 99%

Mitigation Effect of Alkaline Water Chemistry upon Intergranular Stress Corrosion Cracking of Sensitized 304 Stainless Steel.

Wada

Tachibana

Uetake

et al. 2001

J. Nucl. Sci. Technol.

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Alkaline water chemistry (AWC) has been studied as a new water chemistry control to mitigate intergranular stress corrosion cracking (IGSCC) of sensitized type 304 stainless steel (SUS304). The AWC was found to be capable of reducing crack growth rates (CGRs) of the IGSCC. At first, the direct effect of AWC upon IGSCC was studied experimentally. The 1/4T compact tension specimen was used for measurement of CGRs of the SUS304 in high temperature and high purity water. Crack length was monitored by a reversing direct current potential drop method. The CGR of SUS304 at 400 ppb O 2 concentration was reduced ten-fold when solution pH was increased to 9. During this time, electrochemical corrosion potential (ECP) of the specimen did not change so much. Second, it was predicted by a radiolysis calculation that the AWC would reduce H 2 O 2 concentration under the hydrogen water chemistry (HWC). Since the H 2 O 2 concentration was more effectively suppressed by AWC, the required hydrogen concentration in feedwater to lessen the ECP of the reactor components was lower in AWC than at neutrality. Therefore, an indirect effect, that is moderation of the corrosive environment, could also be expected in addition to the direct moderation effect under HWC condition.

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“…75 is calculated from the ratio of the effective cross-sectional :area of the cathode (2. 5 crn 2 ) to that of the "reference electrode" (3. 3 cm 2 ).…”

Section: Fundamentals Of Measurementsmentioning

confidence: 99%

“…On the anode surface, reaction ( 2 ) proceeds and an electric current flows between the two electrodes…”

Section: Fundamentals Of Measurementsmentioning

confidence: 99%

Pressure balanced type membrane covered polarographic oxygen detectors for use in high temperature-high pressure water, (I) Application of guard electrode to improve detector performance at temperatures above 200.DEG.C.

Nakayama

Uchida

1984

J. Nucl. Sci. Technol.

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A pressure balanced type membrane covered polarographic oxygen detector was developed to determine directly oxygen concentrations in high temperature, high pressure water without cooling and pressure reducing procedures. The detector is characterized by the following features:(1) The detector body and the membrane for oxygen penetration are made of heat resistant resin. (2) The whole detector body is contained in a pressure chamber where interior and ex· terior pressures of the detector are balanced. (3) Thermal expansion of the electrolyte is absorbed by deformation of a diaphragm attached to the detector bottom. (4) The effect of dissolved Ag+ on the signal current is eliminated by applying a guard electrode. As a result of performance tests at elevated temperature, it was demonstrated that a linear relationship between oxygen concentration and signal current was obtained up to 285'C, which was stabilized by the guard electrode. The minimum 02 concentration detectable was 0.03 ppm (9.4 x IQ-7 mol/kg).

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Water radiolysis and its effect upon in-reactor zircaloy corrosion

Cited by 151 publications

References 7 publications

On the Temperature Dependence of the Rate Constant of the Bimolecular Reaction of Two Hydrated Electrons

On the Temperature Dependence of the Rate Constant of the Bimolecular Reaction of Two Hydrated Electrons

Mitigation Effect of Alkaline Water Chemistry upon Intergranular Stress Corrosion Cracking of Sensitized 304 Stainless Steel.

Pressure balanced type membrane covered polarographic oxygen detectors for use in high temperature-high pressure water, (I) Application of guard electrode to improve detector performance at temperatures above 200.DEG.C.

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