Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy

M. Kiran Kumar (Corresponding Author), K. Gaonkar, S. Ghosh, V. Kain, M. Bojinov, Timo Saario

    Research output: Contribution to journalArticleScientificpeer-review

    9 Citations (Scopus)

    Abstract

    Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li+ electrolyte at room temperature as a function of potential in a range of −0.8 to +0.3 VSCE. The defect density of the magnetite films formed after each exposure was estimated by Mott–Schottky analysis of capacitances extracted from the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35–40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples during hot conditioning.
    Original languageEnglish
    Pages (from-to)46-54
    Number of pages9
    JournalJournal of Nuclear Materials
    Volume401
    Issue number1-3
    DOIs
    Publication statusPublished - 2011
    MoE publication typeA1 Journal article-refereed

    Fingerprint

    heavy water reactors
    Heavy water reactors
    Ferrosoferric Oxide
    carbon steels
    Magnetite
    conditioning
    Electrochemical impedance spectroscopy
    Carbon steel
    impedance
    magnetite
    heat
    optimization
    spectroscopy
    Defect density
    Film growth
    Oxides
    Electrolytes
    Oxide films
    Optical microscopy
    Capacitance

    Cite this

    @article{dbe885777b244e0ab9451cd0cfd308a1,
    title = "Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy",
    abstract = "Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li+ electrolyte at room temperature as a function of potential in a range of −0.8 to +0.3 VSCE. The defect density of the magnetite films formed after each exposure was estimated by Mott–Schottky analysis of capacitances extracted from the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35–40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples during hot conditioning.",
    author = "{Kiran Kumar}, M. and K. Gaonkar and S. Ghosh and V. Kain and M. Bojinov and Timo Saario",
    note = "Project code: 41745",
    year = "2011",
    doi = "10.1016/j.jnucmat.2010.03.017",
    language = "English",
    volume = "401",
    pages = "46--54",
    journal = "Journal of Nuclear Materials",
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    }

    Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy. / Kiran Kumar, M. (Corresponding Author); Gaonkar, K.; Ghosh, S.; Kain, V.; Bojinov, M.; Saario, Timo.

    In: Journal of Nuclear Materials, Vol. 401, No. 1-3, 2011, p. 46-54.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Optimisation of the hot conditioning of carbon steel surfaces of primary heat transport system of Pressurized Heavy Water Reactors using electrochemical impedance spectroscopy

    AU - Kiran Kumar, M.

    AU - Gaonkar, K.

    AU - Ghosh, S.

    AU - Kain, V.

    AU - Bojinov, M.

    AU - Saario, Timo

    N1 - Project code: 41745

    PY - 2011

    Y1 - 2011

    N2 - Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li+ electrolyte at room temperature as a function of potential in a range of −0.8 to +0.3 VSCE. The defect density of the magnetite films formed after each exposure was estimated by Mott–Schottky analysis of capacitances extracted from the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35–40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples during hot conditioning.

    AB - Hot conditioning operation of the primary heat transport system is an important step prior to the commissioning of Pressurized Heavy Water Reactors. One of the major objectives of the operation is to develop a stable and protective magnetite layer on the inner surfaces of carbon steel piping. The correlation between stable magnetite film growth on carbon steel surfaces and the period of exposure to hot conditioning environment is generally established by a combination of weight change measurements and microscopic/morphological observations of the specimens periodically removed during the operation. In the present study, electrochemical impedance spectroscopy (EIS) at room temperature is demonstrated as an alternate, quantitative technique to arrive at an optimal duration of the exposure period. Specimens of carbon steel were exposed for 24, 35 and 48 h during hot conditioning of primary heat transport system of two Indian PHWRs. The composition and morphology of oxide films grown during exposure was characterized by X-ray diffraction and optical microscopy. Further, ex situ electrochemical impedance spectra of magnetite films formed after each exposure were measured, in 1 ppm Li+ electrolyte at room temperature as a function of potential in a range of −0.8 to +0.3 VSCE. The defect density of the magnetite films formed after each exposure was estimated by Mott–Schottky analysis of capacitances extracted from the impedance spectra. Further the ionic resistance of the oxide was also extracted from the impedance spectra. Defect density was observed to decrease with increase in exposure time and to saturate after 35 h, indicating stabilisation of the barrier layer part of the magnetite film. The values of the ionic transport resistance start to increase after 35–40 h of exposure. The quantitative ability of EIS technique to assess the film quality demonstrates that it can be used as a supplementary tool to the thickness and morphological characterizations of samples during hot conditioning.

    U2 - 10.1016/j.jnucmat.2010.03.017

    DO - 10.1016/j.jnucmat.2010.03.017

    M3 - Article

    VL - 401

    SP - 46

    EP - 54

    JO - Journal of Nuclear Materials

    JF - Journal of Nuclear Materials

    SN - 0022-3115

    IS - 1-3

    ER -