Accelerated and heterogeneous corrosion of Cr-doped uranium nitride fuel pellets

Jennifer H. Stansby; Yulia Mishchenko; Sobhan Patnaik; Vanessa K. Peterson; Patrick A. Burr; Denise Adorno Lopes; Edward G. Obbard

doi:10.1016/j.corsci.2025.113175

Accelerated and heterogeneous corrosion of Cr-doped uranium nitride fuel pellets

Jennifer H. Stansby
, Yulia Mishchenko
, Sobhan Patnaik
, Vanessa K. Peterson
, Patrick A. Burr
, Denise Adorno Lopes
, Edward G. Obbard

Research output: Contribution to journal › Article › peer-review

Abstract

The steam oxidation of Cr-doped UN fuel pellets is analysed during sequential isothermal holds up to 720 °C. In situ neutron diffraction results show how Cr is accommodated in a secondary U₂CrN₃ phase, leading to the formation of a duplex UN/U₂CrN₃ microstructure. Under corrosion, the oxidation of the two phases begins at 400 °C for UN and 430 °C for U₂CrN₃, respectively. Because the UN phase is preferentially oxidised in the presence of U₂CrN₃, addition of Cr in UN based nuclear fuel is found to accelerate the corrosion rate. At 430 °C the oxidation of UN in the UN/U₂CrN₃ microstructure is ∼5 times faster than pure UN, increasing to ∼19 times faster at 460 °C. The oxidation of U₂CrN₃ produces UO₂ via the formation of two transient intermediate phases. In situ neutron diffraction enables oxidation processes of UN and U₂CrN₃ components to be followed separately within the two-phase system.

Original language	English
Article number	113175
Journal	Corrosion Science
Volume	256
DOIs	https://doi.org/10.1016/j.corsci.2025.113175
State	Published - Nov 2025
Externally published	Yes

Funding

The authors acknowledge funding for beamtime proposal P9782 at the Australian Centre for Neutron Scattering (ACNS). JHS acknowledges funding from ANSTO , the Sir William Tyree Foundation and an AINSE Ltd. Early Career Researcher Grant (ECRG). PAB acknowledges the Australian Research Council for financial support through the fellowship IM230100125 . The authors are grateful for the contributions of John MacLeod, Richard Collins, Deborah Wakeham, Chrisopher Baldwin, Daniel Gregg and Grant Griffiths in making the experiments possible.

Keywords

Biphasic
Chromium
In situ
Neutron diffraction
Steam oxidation
Uranium nitride

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10.1016/j.corsci.2025.113175

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title = "Accelerated and heterogeneous corrosion of Cr-doped uranium nitride fuel pellets",

abstract = "The steam oxidation of Cr-doped UN fuel pellets is analysed during sequential isothermal holds up to 720 °C. In situ neutron diffraction results show how Cr is accommodated in a secondary U2CrN3 phase, leading to the formation of a duplex UN/U2CrN3 microstructure. Under corrosion, the oxidation of the two phases begins at 400 °C for UN and 430 °C for U2CrN3, respectively. Because the UN phase is preferentially oxidised in the presence of U2CrN3, addition of Cr in UN based nuclear fuel is found to accelerate the corrosion rate. At 430 °C the oxidation of UN in the UN/U2CrN3 microstructure is ∼5 times faster than pure UN, increasing to ∼19 times faster at 460 °C. The oxidation of U2CrN3 produces UO2 via the formation of two transient intermediate phases. In situ neutron diffraction enables oxidation processes of UN and U2CrN3 components to be followed separately within the two-phase system.",

keywords = "Biphasic, Chromium, In situ, Neutron diffraction, Steam oxidation, Uranium nitride",

author = "Stansby, \{Jennifer H.\} and Yulia Mishchenko and Sobhan Patnaik and Peterson, \{Vanessa K.\} and Burr, \{Patrick A.\} and Lopes, \{Denise Adorno\} and Obbard, \{Edward G.\}",

note = "Publisher Copyright: {\textcopyright} 2025 The Authors",

year = "2025",

month = nov,

doi = "10.1016/j.corsci.2025.113175",

language = "English",

volume = "256",

journal = "Corrosion Science",

issn = "0010-938X",

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TY - JOUR

T1 - Accelerated and heterogeneous corrosion of Cr-doped uranium nitride fuel pellets

AU - Stansby, Jennifer H.

AU - Mishchenko, Yulia

AU - Patnaik, Sobhan

AU - Peterson, Vanessa K.

AU - Burr, Patrick A.

AU - Lopes, Denise Adorno

AU - Obbard, Edward G.

PY - 2025/11

Y1 - 2025/11

N2 - The steam oxidation of Cr-doped UN fuel pellets is analysed during sequential isothermal holds up to 720 °C. In situ neutron diffraction results show how Cr is accommodated in a secondary U2CrN3 phase, leading to the formation of a duplex UN/U2CrN3 microstructure. Under corrosion, the oxidation of the two phases begins at 400 °C for UN and 430 °C for U2CrN3, respectively. Because the UN phase is preferentially oxidised in the presence of U2CrN3, addition of Cr in UN based nuclear fuel is found to accelerate the corrosion rate. At 430 °C the oxidation of UN in the UN/U2CrN3 microstructure is ∼5 times faster than pure UN, increasing to ∼19 times faster at 460 °C. The oxidation of U2CrN3 produces UO2 via the formation of two transient intermediate phases. In situ neutron diffraction enables oxidation processes of UN and U2CrN3 components to be followed separately within the two-phase system.

AB - The steam oxidation of Cr-doped UN fuel pellets is analysed during sequential isothermal holds up to 720 °C. In situ neutron diffraction results show how Cr is accommodated in a secondary U2CrN3 phase, leading to the formation of a duplex UN/U2CrN3 microstructure. Under corrosion, the oxidation of the two phases begins at 400 °C for UN and 430 °C for U2CrN3, respectively. Because the UN phase is preferentially oxidised in the presence of U2CrN3, addition of Cr in UN based nuclear fuel is found to accelerate the corrosion rate. At 430 °C the oxidation of UN in the UN/U2CrN3 microstructure is ∼5 times faster than pure UN, increasing to ∼19 times faster at 460 °C. The oxidation of U2CrN3 produces UO2 via the formation of two transient intermediate phases. In situ neutron diffraction enables oxidation processes of UN and U2CrN3 components to be followed separately within the two-phase system.

KW - Biphasic

KW - Chromium

KW - In situ

KW - Neutron diffraction

KW - Steam oxidation

KW - Uranium nitride

UR - https://www.scopus.com/pages/publications/105010699947

U2 - 10.1016/j.corsci.2025.113175

DO - 10.1016/j.corsci.2025.113175

M3 - Article

AN - SCOPUS:105010699947

SN - 0010-938X

VL - 256

JO - Corrosion Science

JF - Corrosion Science

M1 - 113175

ER -

Accelerated and heterogeneous corrosion of Cr-doped uranium nitride fuel pellets

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Keywords

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