Interpretation of the Rationale for Feed Modification in SCWO Systems

Mitton, D. B.; Marrone, Philip A.; Latanision, R. M.

doi:10.1149/1.1836532

Cited by 28 publications

(28 citation statements)

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“…At the lower temperatures, below 360 C, oxide growth was difficult to detect as the thickness of the oxide was limited relative to the oxide thickness at higher temperatures. The E-pH diagram constructed for Cr, Ni and Fe at 300 C, suggests that the oxides will be stable in the SCW environment in the neutral pH range [Mitton et al 1996]. Oxide development has been relatively slow at the temperature of exposure.…”

Section: Corrosion Resultsmentioning

confidence: 98%

Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Progress Report for Work Through September 2003, 2nd Annual/8th Quarterly Report

MacDonald¹

2003

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Section: Corrosion Resultsmentioning

confidence: 98%

Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Progress Report for Work Through September 2003, 2nd Annual/8th Quarterly Report

MacDonald¹

2003

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“…As in the experiments of Mitton, et al, [57][58] SCC was located in the heater section. In these reactor sections, the transition zone was between the passive and the transpassive regions of the alloy.…”

Section: Corrosion Engineering Sectionmentioning

confidence: 99%

Corrosion of Alloy 625 in Aqueous Solutions Containing Chloride and Oxygen

Kritzer¹,

Boukis²,

Dinjus³

1998

CORROSION

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Alloy 625 (UNS N06625) is used frequently as a reactor material for the oxidation of hazardous organic wastes in supercritical water (supercritical water oxidation [SCWO]). In the presence of chloride (Cl -) and oxygen (O 2 ), all Ni-based alloys corrode fast in high-temperature, subcritical water. High-pressure, high-temperature-resistant tube reactors made of alloy 625 were used as specimens. Coupons were exposed simultaneously inside the test tubes. Experimental conditions included temperatures up to 500°C and pressures up to 38 MPa. Pitting corrosion was observed at temperatures above ≈ 130°C to 215°C. At higher temperatures (up to the critical temperature of water), transpassive dissolution dominated. Under certain conditions, transgranular stress corrosion cracking (TGSCC) appeared in the transition zone between the passive and transpassive regions leading to premature failure of the test reactors. Parts of the corrosion products were insoluble in supercritical water and formed thick layers in the supercritical part of the reactor. Underneath these layers, very little intergranular corrosion (IGC) occurred. In neutral or alkaline solutions and in deaerated hydrochloric acid (HCl), corrosion rates of transpassive dissolution decreased drastically.

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“…Depending upon what species and how much oxygen are present in the solution, SCW can be a very aggressive oxidizing environment. [2][3][4] As such, the corrosion behavior of SCW over this range of densities can vary signifi cantly, [2][3][4][5][6][7][8][9] which is cause for concern over the general corrosion and stress corrosion cracking (SCC) behavior of reactor structural materials and fuel cladding.…”

Section: Introductionmentioning

confidence: 99%

Corrosion of Austenitic Alloys in Supercritical Water

2006

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The purpose of this study was to determine the mechanism by which austenitic iron-and nickel-based alloys oxidize in pure supercritical water. Austenitic stainless steel alloys Type 304 (UNS S30400) and Type 316L (UNS S31603) and nickel-based Alloy 625 (UNS N06625) and Alloy 690 (UNS N06690) were exposed in deaerated supercritical water over the temperature range from 400°C to 550°C. Exposure experiments resulted in the formation of a two-layer oxide on Type 304 and Type 316L in which the outer layer is porous magnetite (Fe 3 O 4 ) and the inner layer is a denser iron-chromium spinel. In Alloy 690 the outer layer is iron-rich and the inner layer is composed of chromia (Cr 2 O 3 ), nickel oxide (NiO), and Ni(Cr,Fe) 2 O 4 . The oxide on Alloy 625 was too thin to measure. Inner and outer oxides have the same grain orientation as the matrix on the stainless alloys, and on Alloy 690, the inner oxide has a common orientation with the matrix but the outer layer consists of randomly oriented oxides. The inner/outer oxide interface is coincident with the original metal surface. The activation energies for oxide growth on each of the alloys, determined from weightgain measurements, are ~210 kJ/mol for the stainless alloys and ~140 kJ/mol for the nickel-based alloys. In both alloy systems, the outer layer grows by outward iron cation diffusion (iron in stainless steel and nickel in nickel-based alloys) and the inner layer grows by inward diffusion of oxygen to the oxide-metal interface. The likely rate-limiting step of the corrosion mechanism is inward oxygen diffusion by a short-circuit process.

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Interpretation of the Rationale for Feed Modification in SCWO Systems

Cited by 28 publications

References 1 publication

Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Progress Report for Work Through September 2003, 2nd Annual/8th Quarterly Report

Feasibility Study of Supercritical Light Water Cooled Reactors for Electric Power Production, Progress Report for Work Through September 2003, 2nd Annual/8th Quarterly Report

Corrosion of Alloy 625 in Aqueous Solutions Containing Chloride and Oxygen

Corrosion of Austenitic Alloys in Supercritical Water

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